Nusatama Berkah - We Manufacture and Export Mining Special Vehicles by Rudy P.

Nusatama Berkah - We Manufacture and Export Mining Special Vehicles by Rudy P.: Nusatama Special Vehicle is a manufacturing company focusing on special vehicle manufacturing for Oil & Gas, Minerals & Mining, Lumber & Forestry and Logistics industry.As a national leade...

This World's Largest Nickel Company Stock Will Triple by 2024

We are mining and exporting Gold, Nickel, Copper, Silver, Zinc, Bauxite/Aluminium and Coal. We also have largest nickel reserve in the world. Our nickel reserve are 353,74 million wet metric ton (wmt) or 230 million dmt, and nickel resources: 1,36 billion wmt or 884 million dmt. 

ANTAM’s main products are high grade nickel ore, also known as saprolite, low grade nickel ore, also known as limonite, ferronickel, gold, silver,and bauxite. ANTAM’s main services are precious metal refining and geological services.

PRODUCTS & SERVICES 

• Precious Metal Price
• Base Metal Price
• Nickel (Nickel Matte, Ferronickel)
• Gold & Precious Metal Refining
• Bauxite & Alumina
• Copper
• Coal
• Iron Ore
• Selenium
• Paladium
• Platinum
• Zinc
• Silver
• Exploration Services
• CSR

BATTERY PROJECT 2024

President Director of the Indonesian Mining Industry or MIND ID (a super holding enterprise that oversees five mining companies: Aneka Tambang, Bukit Asam, Freeport Indonesia, Indonesia Asahan Aluminium and Timah.) Orias Petrus Moedak has confirmed that the Indonesian Holding Battery will manage the electronic vehicle (EV) battery industry in Indonesia in an integrated manner from upstream to downstream. This holding will later take care of the battery supply chain from upstream to downstream in 2024.

Furthermore, Orias explained, PT Aneka Tambang Tbk (ANTM) will work on the upstream or nickel mining to supply raw materials. Meanwhile on the downstream side, Pertamina and PT Perusahaan Listrik Negara (Persero) or PLN will run it.

Furthermore, Orias said that the total project value could reach US $ 12 billion from the two manufacturers of electric vehicle (EV) batteries or batteries for the world's largest electric vehicle, namely Contemporary Amperex Technology Co. Ltd (CATL) from China and LG Chem Ltd from Korea.

"The project value is 11 billion US dollars in total. From the minister, 12 billion US dollars, because the derivative is further away. So that the figure could be up to 20 billion US dollars if a third partner comes in. The calculation is now 12 billion US dollars from upstream to downstream. , "he said.

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Hot Mining and EV Stock to Buy for 2021 And Stay Hot Until 2024

ANEKA TAMBANG  IS A  TRUSTED MULTINATIONAL MINING COMPANY THAT HAVE THE LARGEST NICKEL RESERVE IN THE WORLD.

We are mining and exporting Gold, Nickel, Copper, Silver, Zinc, Bauxite/Aluminium and Coal. Our nickel reserve are 353,74 million wet metric ton (wmt) or 230 million dmt, and nickel resources: 1,36 billion wmt or 884 million dmt.

PT. Aneka Tambang Tbk (ANTAM/ANTM) is a vertically integrated, export-oriented, diversified mining and metals company. With operations spread throughout the mineral-rich Indonesian archipelago, ANTAM undertakes all activities from exploration, excavation, processing through to marketing of nickel ore, ferronickel, gold, copper, iron ore, silver, bauxite, coal, selenium, paladium and platinum.

The company has long term loyal blue chip customers in Europe and Asia. Due to the vastness of the company's licensed exploration areas as well as its known large holdings of high quality reserves and resources, ANTAM has formed several joint ventures with international partners to profitably develop geological ore bodies into profitable mines.

ANTAM’s main products are high grade nickel ore, also known as saprolite, low grade nickel ore, also known as limonite, ferronickel, gold, silver,and bauxite. ANTAM’s main services are precious metal refining and geological services.

PRODUCTS & SERVICES 

• Precious Metal Price
• Base Metal Price
• Nickel (Nickel Matte, Ferronickel)
• Gold & Precious Metal Refining
• Bauxite & Alumina
• Copper
• Coal
• Iron Ore
• Selenium
• Paladium
• Platinum
• Zinc
• Silver
• Exploration Services
• CSR 

Vale Indonesia - We Are a Global Mining Company That Produce Nickel, Manganese, Iron Ore, Copper and Coal

From mobile phones to airplanes, from building structures to coins, minerals are substances for the production of many essential items used in our daily lives.

Vale is the world's largest producer of iron ore and nickel, and we also operate in other mineral areas. With investments in technology and logistics, we guarantee the efficiency, growth, and sustainability of our operations.

Discover our performance in the following segments:

Nickel

Vale is the world's largest producer of nickel. Hard and malleable, nickel resists corrosion and maintains its physical and mechanical properties even under extreme temperatures. The high-grade nickel produced by Vale is greatly sought after for electroplating and battery applications.

This chemical element guarantees the finishing shine of metal taps and the energy for remote controls. It is essential for the production of many items, from coins to cars.

Manganese and Ferroalloy

Manganese, the fourth most used metal in the world, is an element of the composition of several items used in our daily lives, such as batteries, pots, and paint. The mineral is also essential for the manufacture of steel and ferroalloys, which are combinations of iron with one or more chemical elements.

Although almost 90% of manganese production is destined for the steel industry, its applications also include the manufacture of fertilizers, animal feed, and cars.

Copper

Copper is one of the most important metals for the modern industry and, therefore, one of the businesses in which Vale operates. Its thermal energy conductive property surpasses that of any other commercially exploited metal. Malleable, recyclable, and resistant to corrosion and high temperatures, copper is used in the generation and transmission of energy, in wiring and almost all electronic equipment – such as TVs and mobile phones.

Iron Ore and Pellets

Vale is the world's largest producer of iron ore and pellets. Iron ore, an essential raw material for the manufacture of steel, is found in nature in rocks mixed with other elements. Through several cutting-edge industrial processes, the ore is processed to be sold to the steel industries. The iron ore produced by Vale can be found in the construction of houses, manufacture of cars, and production of household appliances.

Coal

Vale also operates in the coal industry, which produces the essential input for the transformation of iron ore into steel.

Metallurgical coal is used in the manufacture of steel and is the focus of our operations and projects. And thermal coal, also produced by our operations, is used to generate heat and energy in thermal power plants.

Where Graphene Can Be Used in Energy Storage Components?

Graphene is a material that has been touted for many applications, both low-tech and high-tech. While it may take some time to make it into many electronic devices as a conductive medium/printable circuitry, it has started to gain a lot of attention and commercial viability in the small-scale energy storage systems, such as batteries and capacitors, which are used in many electronics. In this article, we’re going to look at where graphene can be used in energy storage components.

Graphene is a material that shouldn’t need much introduction if you’re here reading this article. For those who are unaware, graphene is a 2D material composed of all carbon atoms arranged in a hexagonal lattice (much like chicken wire or honeycomb). Many people tout it as a single atomic layer—which it technically is—but in the real-world, it can come in many forms from single-layer to multilayer and even in thinner ribbon-like forms (which are known as nanoribbons). Most graphene forms exhibit a very high electrical conductivity and charge carrier mobility, as well as a high stability to temperature, chemicals, and other stimuli, so it is these properties that have enabled it to gain a lot of interest across various energy storage devices.

Batteries

Graphene-based batteries are the most widely developed energy storage device that uses graphene and have not only been extensively tested in the academic laboratory (in various forms) but are now being produced commercially by some companies within the industry. So, even though the adoption from the end-user markets has taken some time (as it does with any new material that is to be trialed in batteries due to long-term safety requirements), the ability to make them commercially is starting to produce graphene-based batteries in the real-world through the likes of Samsung (who are the biggest company to use graphene) and other smaller battery manufacturers.

Schematic of basic synthesis procedure.

Graphene films are converted from coal tar pitch on the top and bottom surface of Ni layer at 1100 °C for 4 min under low vacuum and a reducing atmosphere.

Graphene, like graphite, is used in the electrodes. However, it’s not often that an electrode is purely made of graphene (there are some exceptions in the academic world), as it is often used in conjunction with graphite to form hybrid electrodes. In some cases, the graphene can be coated on to the surface of graphite electrodes, with one well-known example being the use of Samsung trialing ‘graphene balls’ in electrode coatings. If the original developments from the academic lab are anything to go by, graphene has the potential to be used across many different battery types—and not just Li-ion batteries—to improve the efficiencies, stability, and cycle/discharge cycle rates of the batteries.

Capacitors/Supercapacitors

Capacitors, and supercapacitors (sometimes referred to as ultracapacitors) is another area where graphene is making its way into. The main reason for using graphene is that it has a high surface area, stability, and conductivity (as well as charge carrier mobility) can be utilized to accumulate and store charge—which is the fundamental mechanism of energy storage in capacitors. Of all the capacitor types, graphene has shown the most potential in supercapacitors as they can be used in the carbon coatings on the capacitor plates (instead of activated carbon) to form an efficient electric double layer coating. These supercapacitors can then be used to store large amounts of energy.

While supercapacitors are not utilized as widely as batteries and other capacitors (due to a higher cost compared to conventional capacitors), there is the possibility of supercapacitors experiencing a significant growth increase over other energy storage systems in the next few years, as they could become the more-preferred option in electric vehicles over batteries. As it stands, many different companies graphene-based supercapacitors commercially, so the supply will be there if this demand increase does materialize.

Battery-Capacitor Hybrids

While it is not as common as the two areas mentioned above, another area has emerged which combines both batteries and capacitors into a single hybrid device. As mentioned above, one of the reasons why supercapacitors have not been widely used compared to conventional capacitors and other energy storage mediums is down to cost. One way of reducing the cost has been to create hybrid storage devices which utilize the strength of Li-ion batteries with the rapid charging ability of supercapacitors.

This has been achieved so far by integrating graphene-based supercapacitors into Li-ion modules to increase the lightweightness, energy density, charge, and discharge cycle rates, and stability against the appropriate individual constituents. It’s an area which is relatively new compared to the other energy storage areas, but the benefits achievable could see it grow in the future—especially in areas such as electric vehicles which could benefit from the properties of both batteries and supercapacitors, all while utilizing the properties of graphene.

The 10 largest coal producers and exporters in Indonesia:

• Indo Tambangraya Megah (ITMG)
• Bukit Asam (PTBA)
• Baramulti Sukses Sarana (BSSR)
• Harum Energy (HRUM)
• Adaro Energy (ADRO)
• Bumi Resources (BUMI)
• Mitrabara Adiperdana (MBAP)
• Samindo Resources (MYOH)
• United Tractors (UNTR)
• Berau Coal

Click Here! Top Clean Coal Contractors for Power Plant, Gasification, Liquefaction and Emission Control System

Source: Azo Nano

Hierarchical Porous Carbons (HPCs) for Electrical Double-layer Capacitors Using Low-cost Coal-tar Pitch as a Starting Material

Abstract

A simple and effective template-free method to prepare hierarchical porous carbons (HPCs) has been developed by using low-cost coal-tar pitch as a starting material, anhydrous aluminum chloride as the Friedel–Crafts catalyst, and oxalyl chloride as the cross-linking agent. By a simple controllable Friedel–Crafts reaction, diketone-functionalized coal-tar pitch as the hierarchical porous coal-tar pitch precursor was obtained via a one-step carbonization to provide a well-developed micro–mesoporous network. Nitrogen adsorption and desorption measurements showed that the surface area, pore volume, pore size and pore size distributions of the resulting carbon materials was dependent on the usage of the cross-linking agent. The as-fabricated HPCs have a large Brunauer–Emmett–Teller specific surface area of 1394.6 m2 g−1 and exhibit an excellent electrochemical performance with the highest specific capacitance of 317 F g−1 at a current density of 1 A g−1 in a three-electrode system. A symmetric supercapacitor was fabricated from HPC-DK-1.0 in a two-electrode system, which exhibits a high specific capacitance of 276 F g−1 at a current density of 0.25 A g−1, a high rate capability and an excellent cycling stability with a capacitance retention of 92.9% after 10[thin space (1/6-em)]000 cycles. The one-step carbonization method that produced HPCs for electrical double-layer capacitors represents a new approach for high-performance energy storage.

1. Introduction

In recent years, the design and preparation of organic hierarchical porous carbons (HPCs) has attracted significant attention in academia and industry because of the HPCs unique nanoporous hierarchy, which has potential application in catalysis, gas separation, electromagnetic interface shielding, supercapacitors and fuel cells etc.1–5 To our knowledge, HPCs have been prepared by hard-soft-templating approaches or templating/corrosive-chemical-activation combination methods.6–9 These strategies have achieved great success in the preparation of various HPCs with precise pore structures. However, they have some limitations. For example, the procedure is complicated and tedious because of the required fabrication of templates with a special nanostructure or molecular structure, the removal of hard-templates or post-activation treatment, and many expensive templates are required.10–12 These limitations, result in an uncompetitive price-to-performance ratio for the HPCs compared with other materials for any given application, which limits their commercial viability. An exploration of new template-free preparation methods is urgently required in the study of HPCs.

Coal-tar pitch (CP) is the main by product of the coking process in the coal chemical industry, and is often used to prepare carbon materials because of its relatively low price, sufficient quantity and higher carbon yield. For example, CP can be used to produce needle coke, carbon fibers, mesocarbon microbeads and carbon foam.13–16 In recent years, there has been growing interest in the application of porous carbons in the fields of gas storage and EDLC.17,18 However, preparation of pitch-based HPCs often requires templates or supports, such as mesoporous silica, metal oxides or silicon wafer that caps a metallic layer.19–22 The procedure is too complicated and tedious to apply in practice, therefore, it is imperative that new methods be developed to prepare pitch-based HPC carbons. One of the most widely used strategies to prepare HPCs is by the Friedel–Crafts reaction, in which pitch is polymerized under mild conditions and uses cheap and sustainable building blocks to produce highly porous hyper-cross-linked materials.23,24 Such polymers contain various molecules from oligomers to 3D cross-linking supramolecules with significant differences in molecular size, structure, and pyrolysis behavior. Some light molecules or thermolabile groups in the pitch are removed during the controlled pyrolysis, which could generate abundant mesopores. The devolatilization of the volatile component is accompanied by bubble formation, which occurs first in the vicinity of the primary bubble nuclei. The bubbles coalesce and grow under appropriate conditions, which leads to formation of mesopore voids or macropores in carbonized products.25 Thus, the pitch polymers may be promising candidates for constructing HPCs with explicit mesopore control for high-performance supercapacitors.

We report herein the template-free fabrication of a novel type of HPC by constructing diketone (–COCO–) cross-linking bridges between polycyclic aromatic hydrocarbons (PAH) in CP to yield diketone-functionalized CP (DKCP). The polar carbonyl group has a high reaction activity and favors the modification of CP by providing it with hydrophilic properties that enhance its wettability for polar solvents, and the oxygen functional groups can be used as anchoring sites for metal particles and large molecules.26,27 Such novel bridges can provide a high crosslinking density and oxygen atoms to the hierarchical porous modified CP materials, to achieve the carbonizability of a crosslinking modified CP framework and the inheritability of a hierarchical nanoporous structure. These properties should make DKCP a promising candidate for HPC production with the characteristics of preparation simplicity and easy scalability. The overall synthetic procedure is illustrated in Fig. 1.

Fig. 1 Scheme of preparation mechanism of HPC materials in this study.

2. Experimental

2.1 Materials

The raw CP was obtained from the Anshan Iron and Steel Group Co. Ltd (Anshan, China). A refined coal tar pitch (RFCP) with a softening point of 33 °C was obtained by a mixed solvent-extraction method and its compositions. The main properties of the RFCP and DKCP are shown in Table 1. Anhydrous aluminum chloride (AlCl3) was from Tianjin Guangfu Fine Chemical Reagent Co. Ltd. (Tianjin, China). Oxalyl chloride (OC), hydrochloric acid (HCl) and dichloroethane (DCE) were from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). All chemical reagents were of analytical grade.

Table 1 Bulk and surface elemental compositions of RFCP and DKCPs

2.2 Procedures

2.2.1 Polymerization of RFCP. In this one-step cross-linking approach, oxalyl chloride (OC) was used as an external cross-linker to react with RFCP. RFCP (50 g) was dissolved in 500 mL of 1,2-dichloroethane under argon, before a certain amount of OC and AlCl3 was added to the solution. The resultant mixture was stirred for 6 h at 40 °C to undergo the AlCl3 catalyzed Friedel–Crafts reaction of the RFCP and OC. The reaction was terminated by adding an ethanol–water solution. The product was filtered, washed with an ethanol–water solution that contained hydrochloric acid, and dried under a reduced pressure at 80 °C for 12 h. The obtained DKCPs with different OC/RFCP mass ratios are referred to as DKCP-x, where x represents the mass ratio of OC vs. RFCP. All resultant samples were dark-brown powders.

2.2.2 Carbonization. Sample carbonization was carried out in a tube furnace under atmospheric pressure according to the following procedures. Approximately 10 g of sample was carbonized at 800 °C for 2 h with a heating rate of 2 °C min−1 to yield HPCs. The obtained HPC-DKs with different OC/RFCP mass ratios are referred to as HPC-DK-x, where x represent the mass ratio of OC vs. RFCP. A N2 stream was introduced into the tube furnace throughout the carbonization.

2.3 Measurements and analyses

Fourier transform-infrared (FTIR) spectra were collected on a Thermo Nicolet-360 spectrometer (USA). The elemental content of carbon, hydrogen, and chlorine were analyzed with a Vario Macro EL analyzer (Germany). Thermogravimetric analysis (TGA) was performed to determine the pyrolysis samples by using an HCT-1 instrument (China). Samples morphologies were observed by JSM-6700F scanning electron microscope (FESEM, Japan) and by using a Tecnai-G20 transmission electron microscopy (TEM, USA). Surface chemical composition of samples was studied by X-ray photoelectron spectroscopy (XPS, Thermo ESCALAB250, USA). The surface area and porosity of the samples were estimated from the isotherms of nitrogen adsorption–desorption at 77 K by ASAP2020. The specific surface area was calculated with the Brunauer–Emmett–Teller (BET) equation. The pore size distribution of the samples was calculated based on the density functional theory (DFT) method.

2.4 Electrochemical measurements

The carbon electrode was fabricated by mixing HPCs and polytetrafluoroethylene (PTFE) with a mass ratio of 9[thin space (1/6-em)]:[thin space (1/6-em)]1. Then, the mixture was rolled into a thin film and cut into round films (12 mm in diameter). Each round film with a 2.5 mg cm−2 mass loading was dried in vacuum oven at 120 °C for 2 h, and then pressed onto nickel foams to fabricate supercapacitors electrodes. The obtained electrodes were soaked in 6 M KOH electrolyte under vacuum for 120 min. A button type-supercapacitor was assembled by two similar electrodes and separated by a polypropylene membrane. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were conducted by using a CHI760E electrochemical workstation (Chenhua, Shanghai, China). EIS was carried out over a frequency range of 100 kHz to 0.01 Hz with an amplitude of 5 mV. The galvanostatic charge–discharge measurements and cycle life tests were conducted on a supercapacitance test system (SCTs, Arbin Instruments, USA). The specific capacitance of the working electrodes was calculated from the galvanostatic discharge process via the following equation.

        (1)

    (2)

where Cs (F g−1) is the specific capacitances of the three electrodes system, Ccell (F g−1) is the specific capacitances of the symmetric supercapacitor system, I is the discharge current (A), Δt is the discharge time (s), ΔV is the voltage change (V) that excludes the voltage drop during the discharge process, and m is the mass of the active material (g).

The energy and power density of the symmetric supercapacitor systems were calculated by using the eqn (3) and (4):

    (3)

       (4)

where Ecell (W h kg−1) is the specific energy density, Pcell (W kg−1) is the specific power density, Ccell (F g−1) is the total specific capacitance of the two-electrode cell, ΔV is the voltage change that excludes the IR drop during the discharge process, and Δt is the discharge time.

3. Results and discussion

3.1 Characteristics of RFCP and DKCPs

3.1.1 Elemental analysis and XPS analysis. The elemental analysis of the RFCP and the DKCPs is provided in Table 1. The DKCPs compared with the RFCP have a high oxygen content with an increase in OC content. The decrease of the C/O ratio indicates that the diketone-structure was successfully introduced into the RFCP (Table 1). The introduction of diketone functional groups is key to achieving a highly disordered carbon structure. The introduction of oxygen induces cross-linking of the RFCP structure, which prevents the melting and orderly rearrangement of the RFCP during the high-temperature carbonization process, and inhibits the graphitization process. The evolution of CO and CO2 during the high temperature process changes the microstructure of the carbon materials and plays a dual regulation role.

The surface chemistry of the DKCPs was studied by X-ray photoelectron spectrometric (XPS) measurement (Fig. 2a). The XPS survey spectra show two peaks at binding energies of 284.1 eV and 531.5 eV, which correspond to C1s and O1s, respectively, and suggest that all the samples contain a considerable number of oxygen-containing groups on their surfaces. During the carbonization process, the oxygen-containing groups in the pitch are unstable and can decompose to CO2 and CO during heat treatment and self-activation of the HPC,28,29 which can assist in creating additional pores.

Fig. 2 XPS spectra for RFCP derivatives (a) C1s (b) O1s, and (c) XPS spectra of DKCP-1.0

Information on the chemical state of the elements anchored to the DKCPs surface was obtained from XPS. In the C1s spectrum of the DKCP-1.0 (Fig. 2b), peaks exist for different functional groups, namely C[double bond, length as m-dash]C, C–C, and C–H bonds (284.3 eV), C[double bond, length as m-dash]O bonds (286.5 eV), and O–C[double bond, length as m-dash]O bonds (288.4 eV).30 The O1s spectrum of the DKCP-1.0 (Fig. 2c) can be fitted with two major component peaks. The peak at 531.8 eV is attributed to C[double bond, length as m-dash]O bonds and the 533.1 eV peak results from O–C[double bond, length as m-dash]O.31 These observations show that the DKCPs consists of aromatic carbon with carbonyl and carboxylic functional groups.

3.1.2 FT-IR analysis. As shown in Fig. 3, the absorption peaks at 3040 and 2910 cm−1 result from aromatic C–H stretching vibration and aliphatic C–H stretching vibration, respectively.32 The peak at 1600 cm−1 is attributed to aromatic C[double bond, length as m-dash]C stretching vibration and the peak at 1460 cm−1 is attributed to the C–H bending vibration of methyl and methylene.33 The peaks at 1720 cm−1 is attributed to C[double bond, length as m-dash]O vibration.34 The peaks at 1170 cm−1 is attributed to C–C stretching vibration. The absorption peaks of the aromatic ring skeletal vibrations move to lower wavenumbers after modification, which indicates the degree of conjugation of the aromatic rings. Hence, the degree of polymerization for the aromatic rings increases significantly. Therefore, RFCP can be bridged by OC.

Fig. 3 IR spectrum of RFCP derivatives (a), TGA curves of RFCP derivatives (b), and DTG curves of CP derivatives (c)

3.1.3 Thermogravimetric analysis. Thermogravimetric analysis (TGA) was used with derivative thermogravimetry (DTG) to study the transitions of RFCP and DKCPs at different carbonization temperatures. Fig. 3b shows that both RFCP and DKCPs decompose in a single mass loss stage from 50 to 800 °C. The mass loss results mainly from the removal of gases and light compounds that are generated via thermal polymerization and the cracking of side chains of aromatic rings.35 The carbonization yields of RFCP, DKCP-0.5, DKCP-1.0 and DKCP-1.5 are 16.3%, 41.5%, 55.9%, and 65.9%, respectively, which indicates that the carbonization yield of RFCP can be improved by cross-linking OC. This outcome can be rationalized as follows: OC can react with small molecules in RFCP to from large molecules,36 which decreases the removal of light compounds and increases the carbonization yield. The polar oxygen-containing functional groups from more thermal-resistant materials and increase the carbonization yield of RFCP. DTG curves (Fig. 3c) show that RFCP and DKCPs lose mass at varying rates, as related to the cross-linking degree by OC. The RFCP profile is characterized by a single peak that is centered at 251 °C, which indicates that the mass loss rate at this temperature reaches a maximum. However, three peaks exist in the DTG profile of the DKCPs, which indicates that the main reactions/transformations that occur during the pyrolysis process are similar. The first peak centered at 224 °C (peak I) can be ascribed to the evaporation of absorbed water. Most oligomers in the RFCP fraction are easy to gasify and/or distill below 430 °C,37 which leads to the formation of a DTG peak that is centered at approximately 367 °C (peak II). Above 450 °C, the remaining oligomers and macromolecules cross-link to form larger molecules, even solidified coke. The condensation reactions are accompanied by a release of small molecules, such as CO2, CO, H2O, and CH4, that leads to the third DTG peak that is centered at approximately. 509 °C (peak III).38,39 When the temperature exceeds 620 °C, a carbon-structure rearrangement occurs in the solidified coke and no significant mass loss appears.40 The configuration of small oligomers and large macromolecule networks in the diketone-functionalized pitch polymers leads to a stepwise pyrolysis and aggregation process, which could have a significant effect on the morphology and microstructure of the resultant carbons.

3.2 Characterization of porous structure of HPCs

3.2.1 Brunauer–Emmett–Teller (BET). Porous structures of HPC-RF and HPC-DKs are presented in Fig. 4a by measuring the N2 adsorption–desorption isotherms. All samples display mixture-type isotherms with hysteresis loops, which indicates a combination of microporous/mesoporous structure.41 The N2 adsorption isotherms of all HPC-DK samples show a steep N2 uptake at low relative pressure (P/P0 < 0.001), reflecting the existence of abundant micropores. The adsorption isotherms of HPC-DKs show an evident hysteresis loop in the medium pressure region (P/P0 = 0.4–0.9), indicating that a large number of mesopores exist in these HCPs. Therefore, the HPC-DK-0.5 shows a dominant pore size distribution of less than 2 nm. With an increase of OC mass, a more porous structure emerges in the HPC-DK-1.5 and HPC-DK-1.0. The HPC-DK-1.0 exhibits a more significant hysteresis than HPC-DK-0.5, HPC-DK-1.5, and the HPC-RF in the relative pressure (P/P0) range of 0.4–0.9, which indicates a higher amount of mesopores in HPC-DK-1.0 compared with other HPCs when using the same starting materials and for the same procedure. The porous structure was created by the crosslinking reactions and the heteroatoms in the carbonyl-functionalized pitch are chemically unstable, which provides more “active sites” for carbonization. Thus, the surface functional groups of the RFCP provide a meaningful contribution to the high BET surface area. The calculated structure parameters of a series of carbon materials, including the BET specific surface area (SSA), total and micro-mesopore volume are summarized in Table 2. For a constant sintering temperature, the SSA, pore size distribution, and pore volume of the HPCs are influenced significantly by the mass ratio of the cross-linking agent (OC). It is found that the specific surface areas and pore volume vary with the weight ratios of oxylyl chloride to refine coal-tar pitch (OC/RFCP). The highest BET surface area and pore volume (1394.6 m2 g−1, 1.54 cm3 g−1) are obtained in HPC-DK-1.0. With the increase of OC/RFCP from 0.5 to 1.0, the BET surface area increases from 410.9 m2 g−1 to 1394.6 m2 g−1, and the pore volume from 0.64 cm3 g−1 to 1.54 cm3 g−1. However, a further increase of OC/RFCP leads to a decrease in the specific surface area and pore volume. Therefore, the larger BET surface area and pore volume at large OC/RFCP can be explained as the results of higher crosslinking degree. However, a further increase of OC/RFCP leads to a decrease in the specific surface area. The reason is that when excess OC is used, only one of the two acyl chloride groups in oxalyl chloride reacts with the aromatic rings. As a result, the crosslinking degree of RFCP decreases. The other acyl chloride group on oxalyl chloride is converted into a carboxyl group, as demonstrated by the FTIR spectra of the DKCPs. Fig. 4b shows the pore-size distribution of the HPCs, which justifies the effectiveness of the micropore and mesopore introduction on the HPCs by a one-step carbonization process in the presence of a cross-linking agent (OC). The HPC-DK-1 shows a dominant pore size distribution of less than 2 nm. With an increase in OC mass, a more porous structure emerges in the HPC-DK-1.5 and HPC-DK-1.0. The amount of 3 nm mesopores also increased, which provides a low resistant ionic pathway, and improves the accessibility of the micropores to electrolytes. The number of micropores less than 2 nm increased greatly for the HPC-DK-1.5 and HPC-DK-1.0 samples, as shown in Fig. 4b. The variety of pore sizes with a high pore volume provides highly efficient mass transport through the mesopores and a large SSA from the micro-to mesopores, which achieves an excellent performance for electrical double-layer capacitor applications.

Fig. 4 (a) N2 absorption/desorption isotherms; (b) pore size distributions for the HPC samples.

Table 2 Pore structure parameters of nanoporous carbon materials

3.2.2 SEM and TEM analysis. The HPC morphologies were studied by field-emission scanning-electron microscopy and high-resolution transmission-electron microscopy (HRTEM) (Fig. 5). The (fold)block structure for the RFCP after carbonization was clearly visible, and the mesopore and macropore structures appeared in their matrix as diketone groups that were introduced into the RFCP. The decomposition of carbonyl-functional RFCP was one of the factors that affected their porous nanostructure, and the carbonyl content is the main governing index. Holes were derived from the decomposition of the carbonyl group and the self-assembly foaming process, in which gases formed by pyrolysis/gasification of active precursor molecules lead to the formation of many holes, such as in common foaming processes for preparing carbon foams.42,43 This result is consistent with the composition characteristics of pitch cross-linked discussed above, in which the rich substituent carbonyl groups and the aromatic structures affect the fusibility of the DKCPs significantly, and thus determines the structural properties of the pyrolyzed carbons. The HPC-DK-0.5 contains more oligomers with a lower cross-linking degree, which possesses a lower systemic viscosity and a higher plasticity. DKCP-1.5, in contrast, has many macromolecules with serious cross-linking and so the number of holes on the HPC-DK-1.5 surface is lower (Fig. 5d). The porous structure was verified by HRTEM. The HRTEM micrographs in Fig. 5e and f show that HPC-DK-1.0 is amorphous and has a highly disordered pore structure. Abundant micropores occur with the mesoporous channel walls, which indicates the formation of a continuous three dimensional pore network. This result is consistent with the DFT pore size distribution results.

Fig. 5 SEM images of HPC-RF (a), HPC-DK-0.5 (b), HPC-DK-1.0 (c) and HPC-DK-1.5 (d), TEM images of HPC-DK-1.0 at 100 nm (e), and 5 nm (f)

3.3 Electrochemical properties

The electrochemical performances of the obtained carbon materials were investigated in a three-electrode system in 6.0 M KOH solution. Cyclic voltammetry (CV) curves (Fig. 6a) of the carbonized material electrodes with a scanning rate of 50 mV s−1 exhibited a typical rectangular I–V curve without any redox peak with bumps −1.0 to 0 V, which suggests that all carbonized materials exhibited a pure capacitive behavior.44,45 The HPC-DK-1.0 presented the largest encircling area of the CV curve, which revealed its highest capacitance among the three HPC carbons. Galvanostatic charge–discharge (GCD) curves of HPCs obtained at 1 A g−1 (Fig. 6b) showed almost symmetrical triangles with a tiny deformation, which suggests a reversible electrochemical capacitive performance with a high charge/discharge efficiency. The capacitance of HPC-DK-1.0 calculated from the galvanostatic charge–discharge curve is 317 F g−1 at 1 A g−1 and is significantly higher than that of the carbon materials reported in previous studies.6,9,16,37 The large specific capacitance may be caused by its high accessible surface areas and rich reasonable distributed pores. More significantly, the IR-drops of the HPCs at the start of discharge are less than 7 mV, which suggests a very low equivalent series resistance, an excellent conductivity, and a high mass transfer and/or diffusion rate of ions within the electrode materials. Fig. 6c presents the rate performances of all the carbonized materials. The specific capacitances decrease with an increase in current density for all samples. The behavior is related closely to the pore-size dependent diffusion limitation of ions inside the electrode material at higher current densities.46 HPC-DK-1.0 exhibits the highest capacitance of 317 F g−1 at a current density of 1 A g−1 among the three carbonized materials, which is much higher than that of HPC-DK-0.5 (207 F g−1) and HPC-DK-1.5 (265 F g−1) at the same conditions. At a high current density of 10 A g−1, HPC-DK-1.0 exhibits a high specific capacitance of 242 F g−1, and retains 76.3% of the specific capacitance. The capacitance retentions in the same current range are 73.9% and 69.1% for HPC-DK-0.5 and HPC-DK-1.5, respectively. The high specific capacitance and excellent rate performance of the HPC-DK-1.0 is ascribed to its superhigh BET surface area (SBET = 1394.6 m2 g−1) and well-distributed hierarchical porous structures which provide a high accessible surface for electron accommodation and convenient electrolyte-ion transportation.47,48 Electrochemical impedance spectroscopy (Fig. 6d) was conducted to understand the capacitance mechanism. In the low frequency region, the line that is nearly parallel to the imaginary axis demonstrates an excellent supercapacitor capacitive behavior.49 In the medium frequency region, the inclined line with a 45° slope corresponds to the diffusive resistance of electrolyte ions within the pores of electrode materials (Warburg resistance). In the high frequency region, the semicircle diameter indicates a change in transport resistance (Rct) at the electrode/electrolyte interface.50 The intercept of the semicircle with a real axis (z′) is referred to as the internal resistance (Rs), which includes the intrinsic resistance of the electrode material, the contact resistance between the electrode material and the current collector, and the resistance of the electrolyte solution.51 Electrochemical impedance spectroscopy of the HPC-DK-1.0 presents a short Warburg region and a small semicircle diameter, which means that its hierarchical porous structure favors electrolyte ion access and rapid ion transportation. The Rs value of HPC-DK-1.0 is the smallest among the three HPC carbon electrodes, which indicates its excellent conductivity and improves its supercapacitive performance.

Fig. 6 Electrochemical performance of carbonized material based electrode measurement in a three-electrode system in 6.0 M KOH aqueous electrolyte. (a) CV curves at 50 mV s−1, (b) charge–discharge profiles at 1 A g−1, (c) capacitance at different current densities, and (d) Nyquist plots of porous carbon electrodes with inset showing plots in high frequency region.

The symmetric supercapacitor was assembled by using HPC-DK-1.0 as positive and negative electrode materials, because the three-electrode configuration may produce large errors, and lead to an overestimation of capacitance. Fig. 7a shows typical CV curves of the HPC-DK-1.0 based electrode over scanning rates of 5–200 mV s−1 in a 6.0 M KOH aqueous electrolyte. All CV curves were rectangular without obvious redox peaks at a scanning rate of 5–200 mV s−1, which is characteristic of excellent capacitive behavior.52 No significant distortions in the CV curves result when the scan rate was increased to 200 mV s−1, which suggests rapid ion/charge transport within electrodes and the near-ideal capacitive behavior with a good rate capability. Fig. 7b shows the galvanostatic charge–discharge curves of HPC-DK-1.0 based supercapacitor at different current densities from 0.25 to 10 A g−1. The symmetric linear charge and discharge curves with a negligible voltage drop demonstrate a high coulombic efficiency and a negligible internal resistance. From the discharge curve, the specific capacitance at a constant current density of 0.25 A g−1 was found to be 276 F g−1, which is much higher than that of the RGO-CMK-5 electrode (144.4 F g−1 at 0.2 A g−1),53 the curved graphene electrode (154.1 F g−1 at 1 A g−1),54 and the 3DG-MnO2-13% electrode (36 F g−1 at 0.5 A g−1)55 in a two-electrode system. The capacitance could retain a high value of 196 F g−1 even at a very high current density of 50 A g−1 (Fig. 7c), which indicates the high rate performance of the HPC-DK-1.0 based symmetric supercapacitor. The specific capacitance of HPC-DK-1.0 at different current densities is shown in Fig. 7c. The capacitance decreases rapidly from 256 to 224 F g−1 when the current density increases from 0.25 to 3 A g−1. After that, it drops slowly at high current densities from 3 to 50 A g−1, which reveals the excellent rate capability of the HPC-DK-1.0 electrodes. Such an excellent rate performance is essential for practical application involving a high-rate supercapacitor. The kinetic ion diffusion within the electrode was investigated by electrochemical impedance spectroscopy. Fig. 7d shows the dependence of the impedance phase angle on the frequency of the HPC-DK-1.0 electrode. The relaxation time constant τ0 of the supercapacitor, which is defined as 1/f0 at a phase angle of −45°, represents the point where the resistive and capacitive impedances are equal. For the symmetric supercapacitor that was fabricated from HPC-DK-1.0, the characteristic frequency f0 at a phase angle of −45° was observed to be 1.3 Hz in KOH aqueous electrolyte, which corresponds to a time constants τ0 of 0.77 s, which is nearly equal to 0.73 s of the graphene aerogel of the GA-0.5 electrode,56 and is smaller than that of a conventional activated carbon-based electrode (10 s).57 The very short time constant of HPC-DK-1.0 highlights the critical role of nanopores in promoting the ion kinetic diffusion in the interior of the electrodes.

Fig. 7 Capacitive performance of symmetric electrode for HPC-DK-1.0 in 6.0 M KOH aqueous electrolyte. (a) CV curves at different scanning rates, (b) charge–discharge profiles at different current densities, (c) capacitance retention at different current densities, and (d) Bode plot of phase angle verses frequency.

Cycling stability is one of the most important parameters for practical application of supercapacitors. The cycling stability of an HPC-DK-1.0 based supercapacitor was investigated by a consecutive charge–discharge measurement at a constant current density of 3 A g−1 for 10[thin space (1/6-em)]000 cycles. Although the specific capacitance of the HPC-DK-1.0 electrode decreased gradually with the cycling number (Fig. 8a), a capacitance retention of 92.9% was still obtained after 10[thin space (1/6-em)]000 cycles, which indicates its good electrochemical stability. The rectangular CV profile (Fig. 8a inset) and Nyquist plots (Fig. 8b) with negligible changes after 10[thin space (1/6-em)]000 cycles support this electrochemical cyclability. The small semicircle in the high-frequency region and the almost vertical line in the low-frequency region indicate that HPC-DK-1.0 has an excellent electrical conductivity (Fig. 8b inset). The capability of HPC-DK-1.0 that integrated its high rate performance with an excellent cycling stability is of great importance for high-performance supercapacitors. Fig. 8c shows the Ragone plot of the symmetric capacitor. With KOH as the electrolyte, the energy and the power density were 6.81 W h kg−1 and 25 kW kg−1 at a current density of 50 A g−1, respectively, which exhibits an outstanding power performance.

Fig. 8 (a) CV curves at different cycles, (b) Nyquist plots of different cycles with the inset showing the plots in the high frequency region, and (c) Ragone plot.

4. Conclusions

We have developed a simple and effective template-free method to prepare HPCs by constructing diketone cross-linking bridges in RFCP. The oxygen facilitated extensive cross-linking formation and prevented graphitization. The diketone structure in the pitch is unstable and can decompose to CO2 and CO during heat treatment, which can assist in creating additional pores. The SBET and Vtot of the HPCs increased with the cross-linking agent to precursor ratio. The optimum cross-linking agent to precursor ratio was found to be 1.0, which resulted in a specific surface area of 1394.6 m2 g−1 and a porosity volume of 1.54 cm3 g−1. HPC-DK-1.0 could be one of the best electrode materials for supercapacitors with a high specific capacitance of 276 F g−1 at a current density of 0.25 A g−1 and a high capacitance retention of 92.9% after 10[thin space (1/6-em)]000 cycles in a symmetric two-electrode cell because of its high surface area, small inner resistance and high electrical conductivity. These results show that these porous carbon materials are promising for use in high-performance supercapacitors.

Source: Haiyang Wangab, Hongzhe ZhuORCID logob, Shoukai Wang*b, Debang Qia and Kaihua Shen*a

a The State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian

b Sinosteel Anshan Research Institute of Thermo-Energy Company Limited

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8. Samindo Resources (MYOH)
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10. Berau Coal

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History and Uses: Carbon

Introductory Remarks

Carbon compounds are rather prominent on this planet. They are called organic compounds and are found in abundance in what's called "biology". For example, the following three simple and well-liked molecules contain plenty of carbon (C):

1. C₂H₅OH. Chemical short-hand for the (ethylene) alcohol found in beer, red wine and other important liquids.

2. C₆H₁₂O₆. Known as starch and found, for example, in pasta and other necessities of life.

3. C₆H₁₀O₅. Sweetening life because it's (glucose) sugar.

There are a hell of a lot (million, billion, trillion, whatever you like) more organic molecules around, including DNA and other rather complex stuff. Pretty much all of them could be used to make carbon.

We also have carbon compounds in gases like the carbon dioxide (CO2) that provides the fizz in soda and changes the climate, or carbon monoxide (CO) that kills you and allows (carbon) smelting of metal ores.

Elemental carbon, however, is not so easy to find. Ancient humans pretty much only encountered it in the cinder, soot, and charcoal leftovers found after some tree was hit by lightning and burned down, or after they started to make fire themselves on a regular base (some 300,000 to 400,000 years ago; possibly even more than 1 Mio years). Whatever black stuff remains after a careless burning of organic material is very dirty carbon. The greyish stuff is ash, consisting of inorganic "salts".

The name carbon comes from the the French "charbone", which in turn came from Latin "carbo", meaning "charcoal". In German the name is "Kohlenstoff" which literally means "coal-stuff".

Looking around today, we can find more or less elemental or natural carbon in the following modifications:

• Residues of (incomplete) burning as outlined above. The best you could do for producing pure carbon was to go for charcoal or soot deposited on some surface.
• Coal; coming in various grades from lignite with about 60 % - 75 % carbon content to anthracite with > 91.5 % carbon content.
• Graphite, the hexagonal form of crystallized carbon.
• Diamond, the cubic metastable form of crystallized carbon.

Synthesized or man-made carbon adds a few more versions; use this link for details.

The History of Carbon thus has several main and subsidiary branches:

• The history of all its modifications before it was known that they all are just different expressions of the same element.
• The history of figuring out what the element carbon can do after its nature became clear.
• The history of the relation of carbon and iron.
• The history of organic chemistry.
• .....

Let's start with the first branch.

History of Carbon Modifications

Charcoal

Charcoal results when (dry) wood is heated to at least 275 oC (527 oF) in an oxygen-free environment. The wood then can't burn or oxidize with the basic reaction C + O2 → CO2 but pyrolyzes to carbon (in the form of charcoal) and various gases.

Pyrolysis is the fancy word for "thermochemical decomposition of stuff" or simply the falling apart of chemical compounds when you heat the stuff but don't supply oxygen for a proper burning. "Pyr" is Greek for "fire" and the root of the English word "pyre"; "lysis" is Greek for "separating" as in "electrolysis".

Chemically speaking, wood is mostly a mixture of cellulose (40% – 50%), hemicellulose (15% – 25%) and lignin (15% – 30%). Chemical formulae for that kind of stuff are, for example, (C6H10O5)n for polysaccharide cellulose, or C10H12O3 for a lignin variant.

In other words: besides carbon (C) wood contains quite a bit of oxygen (O) and hydrogen (H). It is thus not surprising that the gases formed during pyrolysis are mostly carbon monoxide (CO), hydrogen (H2), methane (CH4) and carbon dioxide (CO2). Note that the first three gases burn readily - if there is oxygen available.

Pyrolysis of pretty much all organic stuff (including you) thus can be done for several purposes:

• Making charcoal needed for old-fashioned smelting or modern barbecuing from wood.
• Making coke for modern smelting from coal.
• Making combustible gases needed, e.g., for driving a car if no gasoline is around, from coal, wood, plants, waste, ....
• Cleaning up organic waste including toxic and smelly stuff by turning it into coal and gases.
• Turning old tires into coal / coke, diesel oil and combustible gases (then used for firing the plant).

The first two processes we will encounter more often in this Hyperscript, they relate directly to iron and sword making. The last two items are hot topics in our modern waste-producing American way-of-life world.

Number 3 is now out of style but, believe it or not, was quite prominent in WW II Germany. Gasoline was scarce and cars and trucks had a "wood carburetor", or more precisely, an unwieldy gas generator for pyrolyzing wood, a feed tube for the gases, and a carburetor etc. adopted to feeding the gas to the engine. The picture below shows it all.

It wasn't much fun to run a wood-fueled car. But that was still far superior to not running a car at all. I guess that the urge for getting away on wheels is second only to drinking beer, which comes right after urge No.1.

German car around 1940, running on wood as fuel

   

Having decent charcoal around was important for millennia. Charcoal was decisive for:

• Smelting of metals from the ores.
• Melting of the smelted metals for casting.
• Forging of non-meltable iron and steel.
• Making glass and advanced pottery.This coul also be done with dry wood, hoever.

Charcoal making is relatively easy and was done in pretty much the same way for thousands of years. Wood is all that is needed. Northern Europe thus had no problem in this respect for quite a while, but ancient Egypt, for example, had not much wood at its disposal and was thus at a certain disadvantage concerning the charcoal-enabled technologies given above. On the other hand, they didn't need wood as urgently as my forebears to keep warm during the 9 months when it is cold.

Charcoal in the time-honored fashion is produced by pyrolyzing a pile of wood that is contained in an (almost) airtight enclosure made from mud bricks or stuff like that. Shoveling earth on the pile might already do the trick. Of course, the ignorant charburners and the important well-educated or at least rich people didn't call it "pyrolyzing" for the first few thousand years but "burning" because some (small) part of the wood is really burnt. For that you needed to have a few vents in the mud cover, and the initial burning proper produced the heat to get the pyrolysis going in the larger part of the pile.

The pictures below show what a charcoal pile looked like since about 1.400 AD. Before that, the wood was simply thrown into a pit in the earth, set on fire and then covered to prevent all-out burning.

Charcoal making 1910. Next, the pile will be covered with earth.

The internal structure of a charcoal pile

   

As soon as the process has been started around 275 oC (527 oF), it is self-supporting since pyrolysis generates heat of its own and thus raises the temperature. The process continues until all the wood has been converted. As a rule of thumb, 5 tons of wood make 1 ton of charcoal.

Of course, since wood contains more stuff besides the major ingredients listed above, all the non-burnable stuff (called "ashes" in burning proper) is now contained as dirt in the charcoal. Have you ever wondered why flour (mostly starch) in Germany has always a number on it like "type 405" or "type 1050"? This number just gives the weight of the remaining ash in milligram (mg) if you burn 100 grams (g) of the flour. The more ash, the more minerals are in there. Ash generally accounts for 1 % or less of the weight of (dry) wood. For some odd reason my wife thinks that ash is good for you when she uses flour for baking.

Wood ashes consist mainly of oxides of calcium (Ca), potassium (K) and magnesium (Mg). These oxides account for roughly 80 % of the ash; next come oxides of aluminum (Al), phosphorous (P), sulfur (S) and a few more.

Charcoal retains the original cell structure of the wood and thus is very porous or, in other words, has a large surface-to-volume ratio. That's why it burns far better and hotter than wood or regular coal. There is simply more surface area where the process can take place; see below:

Charcoal (probably from pine) conserved in slag during early iron smelting

Of course, ever-present "sympathetic magic" was invoked to relate hard iron to charcoal made from hard wood and soft iron to charcoal from soft wood, etc. It is true to some extent that charcoal made from hard wood might make your iron hader, i.e having a higher carbon content - but no because of magic but for good scientific reasons. It was a good idea to be very concerned about the charoal that you used in your smelter, and smelter operators had a strong tendency to never chane a "winning team".

When metal smelting became a major industry, let's say ever since 500 BC, de-forestation became a problem. Wood or charcoal had to be transported over ever increasing distances, and there is some speculation that the depletion of wood resources lead to the decline of whole empires, e.g. in Africa, (for example the famous Kingdom of Kush), where iron was smelted as early as 900 BC.

Charcoal burners or Charburners were a-plenty in ancient metal-working society but their profession usually had a somewhat seedy reputation. Of course, throughout most of history, the useless but powerful nobility looked down on manual labor anyway, and the appearance of always black and dirty charburners did not particularly recommend them as good companions.

Diamond

In a few areas around the globe raw diamonds could be found just so; in particular, it appears, in deposits of some Indian rivers. Diamonds have been known in India for at least 3,000 years, maybe even 6.000 years. What exactly people did with them is unclear. They were used as (uncut) gemstones, religious icons (whatever that might be) and as tools for scratching and working hard things.

The name diamond (German: Diamant), you guessed it, derives from the ancient Greek "adámas", meaning "proper", "unalterable", "unbreakable", and so on. I would guess that it is the same root as "atomos", meaning indivisible or uncuttable, which gave us the "atom" - but it is all Greek to me.

Diamonds have a simple cubic face-centered (fcc) structure like silicon (Si) or germanium (Ge) as shown below.

Diamond crystal structure

Blue and green spheres mark the position of carbon atoms, the blue spheres mark also the position of lattice points. Red lines show the bonds between atoms. The black lines are meaningless, they just guide the eye to identify the cubic structure.

A Chinese work from the 3rd century BC refers to diamonds as amulets of foreigners (warding off evil influences) while the Chinese themselves used (imported) diamonds as tools for working jade. While diamonds for millennia came mostly from India, Brazil (major finds in 1725) and South Africa (major finds 1867 in Kimberley) eventually took over.

Small numbers of diamonds began appearing in European jewelry in the 13th century; they were used as "accent points" among pearls set in gold. Louis IX of France (13th century) reserved diamonds for the king by law, demonstrating that this piece of carbon was now seen as extremely valuable.

The big days of diamond, lasting until today, started when the facetted cut that we have today as a matter of course was invented by Jules Cardinal Mazarin in the 17th century.

Diamonds are a metastable phase of carbon; the stable phase is hexagonal graphite. The formation of diamonds therefore requires very specific conditions: rather high pressure (around 5 GPa) and high but not excessively high temperatures (around 1.000 oC). That makes it rather difficult to grow big single diamond crystals in the laboratory. On the other hand, making small diamonds or coating all kinds of materials with a thin layer of diamond is now commercial routine.

The black stuff left in your oven, after doing your turkey or whatever, contains what one could call "amorphous diamond" with a lot of strong diamond-like bonds. It is thus not surprising that this annoying matter is very hard and durable and almost impossible to scratch off or to dissolve in chemicals that don't tend to kill you on the side.

   

Coal and Coke

Coal is the black stuff we dig out of the ground in ever increasing quantities. The table below lists the 8 biggest producers; there are of course many more.

   

Most of that coal ends up as carbon dioxide (CO2). Frightening, isn't it? A lot of this is used to produce the - roughly - 1.200 Mio tons of steel per year.

In some areas of the world coal seams came out of the ground, and coal then was just dug out and used on a small scale, e.g. by the Romans. Wikipedia writes: "In Roman Britain, the Romans were exploiting all major coalfields (save those of North and South Staffordshire) by the late 2nd century AD. While much of its use remained local, a lively trade developed along the North Sea coast supplying coal to Yorkshire and London. This also extended to the continental Rhineland, where bituminous coal was already used for the smelting of iron ore."

I can't quite believe that. Smelting iron ore with bituminous coal, or any coal for that matter, would generate very inferior steel because of the sulfur problem. My guess is that smelting and melting have been confused once more.

Major use of coal started when Great Britain had finally cut down most of its forests in the 16th century. The use of coal as domestic fuel rapidly expanded, as did the diseases caused by the smoke. The industrial revolution in the 19th century finally led to an explosive growth of coal mining that has essentially continued to this very day.

   

Bitumineous coal seam exposed at the beach

Coal, mind you, is not a well defined substance and it is not carbon as already pointed out above. In the best case (anthracite) it contains about 10 % foreign matter, in the worst case (lignite), dirt accounts for around 40 %. The non-coal stuff contains mostly oxygen and hydrogen. But all grades of coal, unfortunately, contain about 1 % of sulfur, and that is rather bad for steel production, not to mention the environment (look up "acid rain").

The figure below gives a schematic view of the composition of coal.

Composition of coal - very schematic and three-dimensional

Source: Adopted from wikipedia; Obscure old Russian text book from A. I. Kitaigorodsky

   

If there would only be ordered arrays of those hexagons, it would be pure graphite. Wherever two lines meet in the upper picture sits a carbon atom and a hydrogen atom (mostly not drawn). Where three lines meet is only a carbon atom.

Coke (short for “coal-cake”), is to coal what wine is to grapes: a highly refined and superior product in comparison to the raw material it was made from. One could also say that it relates to coal the same way charcoal relates to wood. Coke here, to be perfectly clear, is not something you snort up your nose.

In a nutshell: coke results when you pyrolyze coal. Rather pure carbon is left over, and as a by-product coal-gas, and coal-tar are produced in large quantities. These by-products created their own industries. Coal gas (also called town gas and illumination gas) was the primary source of gaseous fuel for lighting, cooking and heating in many cities in the 18th and 19th century. Coal tar was used for making all kinds of early organic compounds like creosote.

In the western world, Sir Hugh Plat (1552–1608), an English writer and inventor, first suggested the process in 1603. Nobody heeded his idea, of course, until the need to have something that could replace charcoal became a matter of life and death. Charcoal was becoming expensive in merry old England in the 16th century because the forests were mostly cut down by then, and that meant that metal smelting became expensive. Well, yes, but who cares?

Far worse was that beer brewing and thus beer became expensive, because you need a good fuel to roast the malt needed for making beer! You just can't run a decent civilization that smelts metals and is bent on conquering the world (or at least the French) without large quantities of good and affordable beer, as I have ascertained before. Using coal for roasting the malt impairs a foul taste to the beer because of the sulfur in the coal. Making coke became imperative, and beer brewing with coke started 1642 in Derbyshire for good.

Of course, after the bulk supply of beer was ensured, coke could then also be used to smelt metals, make swords and later guns, and all the other hardware needed for conquering the world. It took a while, however. It was not before 1710 that one Abraham Darby (1678 – 1717) developed a method of producing cast iron in a blast furnace fuelled by coke rather than charcoal. It took even longer before that caught on - only around 1800 pretty much all blast furnaces were run on coke. Some charcoal fanatics, however, where not convinced even then and kept their smelters on charcoal well into the 20th century

The Chinese did it the wrong way around. They started to make coke already in the 9th century AD but didn't use it for making first beer and then iron. They somehow got confused and started smelting iron with coke right away. In the 11th century they had a major iron industry running that was based on coke and not just charcoal. That kept them so busy that they never got around to making decent beer.

Poor suckers, it was downhill ever since. They could have conquered the world quite easily in the 15th century, long before the Spaniards and Portuguese made their bid, because they had superior hardware and ships, and many other advanced things like live-in concubines. Fortunately (for us), they didn't have the balls beer needed for some conquering. Now look at the British and the Germans. They focussed on beer for quite a while - and the British eventually did conquer most of the world and they still feel good about that! We Germans weren't quite that successful but at least we tried. The Americans today have some success, but their conquering-the-world efforts get rather mixed reviews. I blame it on the quality of their beer.

   

Graphite

Graphite is the stable phase of carbon with a hexagonal lattice. It is not a simple hexagonal close-packed structure but a bit more complicated as shown below.

Graphite Crystal structure

The bonds in the hexagonal plane are very strong just like in diamond, while the bonds between the planes are very weak. That's why it is very easy to deform graphite in directions parallel to the hexagonal planes and very difficult in directions perpendicular to it. That allows applications that are breathtakingly different:

• Use poly-crystalline graphite. Whenever you press or pull on it, some areas shift easily and stick to the contact material. This is great for making pencils or lubricants.
• Use monocrystalline graphite in long fibres oriented in the hexagonal plane. When you pull at the fibres, you are trying to break diamond bonds and that is tough to do. Now protect your fibres from forces at right angles by encasing them in some epoxy. Bingo! You have made carbon-fiber-reinforced polymer or plastic (CFRP or CRP) with a strength-to-weight ratio that exceeds the best steels by far.

The name "graphite" was coined by one Abraham Gottlob Werner in 1789 from (what else?) ancient Greek: "grapho" = to draw, to write, because it was used in "lead" pencils. This already gives a hint that there was some confusion as to the nature of the stuff in pencils. People thought for a long time that natural graphite was some lead mineral.

Graphite is quite essential to modern technology. It is not only good for pencils, as a lubricant, or for CFRP; it is an electrical conductor that can take enormous temperatures (it doesn't melt but becomes directly gaseous around 3.750 oC (6780 oF) and is chemically very stable. That's why it is used in the high-temperature "electro" smelting of difficult elements like silicon.

Graphite may be considered as the highest grade of coal (above anthracite) and therefore is found in small quantities wherever coal is found. It was used pretty much throughout history as "black paint", it seems, e.g. on pottery. Personally, I'm not sure if the graphite paint found on old pottery resulted from using "true" graphite or just soot. After firing the pots, the result could be about the same.

Graphite proper came into its own after a huge deposit of extremely pure and soft stuff was discovered in 1565 (or possibly somewhat earlier) in the Borrowdale parish, Cumbria, England. The local yokels used it for marking sheep and probably didn't worry much about what that soft black stuff actually could be. A somewhat more advanced use coming up a bit later was to line the molds for cannon balls with this graphite, resulting in rounder, smoother balls that could be fired farther.

The military guys did wonder about what that useful black stuff could be, and promptly confused it with lead or some of the more common lead ores like galena. That is why graphite was known for a long time as "lead" or "plumbago" (based on the Latin "plumbum" for lead). This error survived to some extent up to the present day. In German, a pencil is still called "Bleistift", literally "lead pen". Archeologists also confused lead and lead ore. Granted that graphite, lead and galena look similar, one could at least distinguish graphite from the two others easily because the difference in (specific) weight is rather obvious, you might think. Yes, but to everybody before - roughly - 1750, the notion of chemical elements was unknow. Things that were similar were thought to be about the same. The differences were assigned to the presence or absence of "vital juices", "spirits" or "priciples" of this or that. Graphite in many aspects is far more similar to lead or lead ore then to diamond, or soot. I'm quite sure that even today it would be far easier to persuade most people that graphite is related to lead and not to diamond.

 

Soot and Carbon Black

Soot is that fine black stuff that remains in the air from burning something, and that the chimney sweep takes out of your chimney on a regular base. You only can avoid it in very "clean" fires. It results from the "incomplete combustion of a hydrocarbon", for example when a candle burns wax. Put a glass plate over a candle flame and you catch the soot in the air. It is part of what we call "smoke" and accounts for a lot of sick people, especially in countries where open fires are the standard for cooking.

Soot consists of rather small (below 100 nm) particles of carbon (plus some dirt). This particles might agglomerate to some extent, forming chains and God knows what, and at least parts of them consist of amorphous carbon. I'm sure, however, that you will find all other forms of carbon too, if you search long enough.

Atomic structure of graphitized carbon black; HRTEM picture

The parallel lines are small graphite (nano)crystals; you look at the hexagonal planes "edge-on".

Source: Obscure old Russian text book from A. I. Kitaigorodsky; actual source not identified.

   

Soot, made unintentionally by you via burning something, should not be confused with carbon black that is made intentionally (by burning something). Carbon black is rather pure carbon that serves as raw material for important carbon-based products. It is, for example, used as pigment in your toner cartridge, and it is what makes care tires black. World production is around 10 Mio. tons a year. Make it very hot and it graphitizes as shown above.

And don't confuse "carbon black" with Black Carbon - look it up yourself!

Ancient man used soot for painting himself, for tattooing, painting caves, whatever. It was not High-Tech and thus is not very interesting to us.

Modern man like me and my colleagues used very pure carbon black for a while in experiments designed to make very pure silicon via "electro-smelting of difficult elements". That also needed very clean silicon dioxide (SiO2). It didn't really work but that is another story. Working with the stuff makes everything (including you) quite black, too. I have never done anything quite that dirty again during my career, and that includes convincing my kids that the shortcuts I proposed on major hikes would bring us home pronto, not to mention running a major university faculty as Dean.

History of Putting Things Together

It's Carbon!

You must admit that anybody not familiar with the basics of chemistry and the periodic table would declare you to be completely nuts if you would propose that all the stuff described above is one and the same basic substance. Before about 1700, "anybody not familiar" and so on would simply have been everybody minus a handful of fledgling scientists.

It was Robert Boyle who suspected in 1661 that there were more than just the four classical elements that the ancients had postulated. He endorsed the view of elements as the undecomposable constituents of material bodies and made a distinction between mixtures and compounds. Nevertheless, he was also an alchemist (and a racist) and believed in the transmutation of metals - making gold from lead, in other words.

Antoine Lavoisier, the "father of modern chemistry" whom we have encountered before, supplied the first list of elements in his "Traité élémentaire de chimie (Elementary Treatise on Chemistry) in 1789. Oxygen, nitrogen, hydrogen, phosphorus, mercury, zinc, and sulfur were (correctly) identified as elements - but also light and "caloric" (heat stuff), which he incorrectly believed believed to be a material substance. In 1775 he also recognized soot as being the element carbon, and more importantly, established that diamond was also carbon by doing the amazing experiment described below.

While Lavoisier's work was daring and pioneering, we need to be aware that Lavoisier could not really prove beyond any doubt if some substance was an element or a compound. His inclusion of carbon, while correct, could also be seen as a lucky guess. It was not clear, for example, which manifestations of the element were really carbon. Some experiment by one Guyton de Morveau much later in 1799 lead others to believe that only diamond would be pure carbon, while graphite would be an oxide of the "1st degree", charcoal of the 2nd degree, and carbonic acid, finally, would be the "complete oxide". Pepys and Allen corrected that in 1807, which helped Dalton in formulating his "law of multiple proportions" in 1808, paving the road to atoms and the periodic table.

Of course, Lavoisier was neither alone in his enterprise nor did everybody believe him right away (or later, considering that there are mistakes; see below). The eminent Priestley, for example, also credited with "discovering" oxygen, never believed him at all.

It goes wothout saying that the people actually making and working with iron and steel couldn't have cared less for quite a while. Major insights were fine around then but usually not all that helpful for practitioners.

Elements according to A. Lavoisier

Source: Wertheim's book. Obviously from an early translation to English.

   

Some time in 1772, Lavoisiser and some of his buddies pooled their funds, purchased a diamond, put it into a closed glass jar, and focussed the rays of the sun on it with a big lens, supplying the ultimate "clean" heat. The diamond disappeared and since the weight of the glass jar was unchanged, the unavoidable conclusion was that the diamond had turned into a gas that could only be carbon dioxide, proving that a diamond was pure carbon.

The experiment was not as simple it as it appears nowadays, as this contemporary illustration proves:

Burning diamonds in style

Source: http://historyofscience.free.fr/Comite-Lavoisier/f_galerie_sur_lavoisier.htm

I don't know how Lavoisier's insight was received by the public but will bet that almost nobody believed him (and that his wife was mad at him for destroying that diamond). The judge who had him beheaded in 1794 said: "La République n'a pas besoin de savants ni de chimistes ; le cours de la justice ne peut être suspendu" (The Republic needs neither scientists nor chemists; the course of justice cannot be delayed).

Well, Lavoisier also supported the metric system, and fought for the rights of a number of foreign-born scientists, including mathematician Joseph Louis Lagrange, during the Reign of Terror, so he had it coming for himself.

In essence, the 18th century was when "chemistry" was born. This was a difficult delivery because it required not only to do away with the "four element theory" (plus "aether" or "quintessence", added by Aristotle, being wrong as ususal, as the fifth element) but also to get rid of the more modern "phlogiston" theory. Boyle and Lavoisier, mentioned above, were decisive in this enterprise, but also a lot of other fledgling scientists.

Carl Wilhelm Scheele noticed in 1799, four year after Lavosisier recognized soot to be carbon, that graphite was carbon, too. Scheele also proved (as far as was possible) the elemental character of: Barium (Ba), Chlorine (Cl), Fluorine (F), Manganese (Mn), Molybdenum (Mo), Phosphorous (P), Oxygen (O) Nitrogen (N), and Tungsten (W).

Of course now you wonder. Just above I wrote that Lavoisier had oxygen, nitrogen and so on listed as elements - and that was earlier. Well, as far as oxygen is concerned, I must also mention Joseph Priestley who described a special gas - we call it oxygen - in 1774, even before Lavosisier. I guess the discovery of oxygen and nitrogen was in the air, so to speak. As far as priorities go, Scheele probably made his discoveries in 1773, even before Priestley, but published it later than Lavoisier. Whatever, Priestley and Lavosier were English and French and thus not trustworthy; look what they did with Lavoisier. Scheele was German and now you could believe it. Scheele won ever-lasting fame by being instrumental in overturning the phlogiston theory.

Smithson Tennant, an English chemist, not only discovered the elements iridium (Ir) and osmium (Os) but proved in 1797 once more, but now also beyond reasonable doubt for the imbecile, lawyers and politicians, that diamond is indeed a phase of carbon. He did that together with his assistant William Hyde Wollaston, another well-known name in scientific circles, by reacting one part (= mol) of carbon with two parts of oxygen, obtaining nothing but carbon dioxide (CO2).

So at the beginning of the 19th century it was clear that soot, graphite, diamond, coal, coke and charcoal were just different manifestations of the element carbon, containing more or less "dirt" on the side.

In the following 150 years the understanding of carbon manifestations was refined and developed in great detail but nothing really new was added to the list above until about 1950 when (small) diamonds could be synthesized to some extent. Somewhat later, around 1970, the new and exciting carbon manifestations known under names like "Bucky balls", fullerenes, carbon nanotubes and graphene, started to appear, causing major scientific orgasms. The party is still on. This is described in another module.

 

It's Carbon That Makes Steel!

Everybody involved in the early iron and steel industry knew that the there were pronounced differences between (wrought) iron, steel and cast-iron and that one could change the properties of these materials to a large extent. One could even make steel from both wrough iron and cast-iron by some proper processing. Some of the practitioners of old must have given some thought to the question of what is responsible for the differences. Unfortunately, none of them wrote it down, or if somebody did, it was lost.

Most people thinking about that probably followed Aristotle and considered steel to be a more refined form of iron and thus were completely wrong. The question thus is: When did it become clear that steel is actually "dirty" iron, and that the most important dirt in this context was carbon? The answer is: In the 17th / 18th century - but details are a bit muddled. It can't be otherwise. You cannot possibly figure out that carbon is the decisive element for steel making if you lack both: a valid concept of elements and an idea of what is carbon.

We do know, however, that René Antoine Ferchault Réaumur (1683-1757) figured out that steel is "dirty" iron. He may not have been the first one to entertain this notion but he did clever experiments and wrote about it at length. It's the same Réaumur, by the way, to whom we owe the Reaumur scale for measuring temperatures. He is famous for a lot of other things but he seems to be the first (proto)scientist who conducted a systematic study into the production of steel. That wasn't just for fun. In the early 18th century the French iron and steel industry was seriously backward, and the French, intend on conquering the world even so they lacked decent beer, needed decent hardware for fighting and shooting.

Réaumur was able to obtain documentation concerning the iron and steel industries of foreign countries and his direct boss, Philippe II, duke of Orleans, subsidized Réaumur’s research by granting him a pension of 12,000 livres (presumably a lot) to further his studies concerning iron and steel.

In Réaumur's times the basic product of the ferrous industry was "pig iron" (= cast-iron) from early blast furnaces, from which wrought iron was made. Steel was produced by "cementation", i.e. by mixing iron and charcoal and heating the mix for weeks, until the iron was carburized to what was called "blister steel". France somehow missed the advent of this new technology but Réaumur knew about it and thus didn't have to think too hard to get the idea that steel was iron plus something. It's however, not quite as obvious as it looks to us. Not knowing that wrought iron is rather pure iron, the cementation process could just as well have sucked something out of the wrought iron and thus turned it into steel.

Réaumur went at it systematically and did what a true scientist would do: He charged lots of identical small crucibles with wrought iron plus all kinds of stuff that could supply the "cement" needed for making steel, and heated the mix under "rigidly" controlled conditions. Essentially he tried to change just one variable from experiment to experiment, exactly the right thing to do even in modern science.

After a large number of experiments Réaumur concluded that the best mixture for making steel out of iron was to use a specific combination of chimney soot, charcoal, ashes, and common salt.

More important, his general conclusion was that steel was in fact impure iron, somehow intermixed with “sulfurous and saline particles.” More than that, he also concluded - correctly - that cast-iron was even more impure than steel.

But sulfur? Looks like he didn't recognize that the essential stuff needed to make steel was actually carbon? Well - carbon hadn't been "invented" yet, look above. In the early eighteenth century chemistry, “sulfurous” was the general term for inflammable stuff or for the "oily principles" contained in combustible substances, such as charcoal, soot, or whatever else could be lit up. It didn't just mean the element sulfur (S). Thus Réaumur was rather close to answering both essential questions from above in 1722, when he published his studies entitles "The art of converting wrought iron into steel" and "The art of making cast iron malleable" (of course the original titles were in Latin).

Réaumur actually did far more. He investigated the structure of fractured iron and steel pieces and tried to explain a lot of things from the differences he observed (iron - fibrous; steel - lamellar; cast-iron - granular; not too bad). Lacking a microscope and proper preparation methods, not to mention the concept of atoms, crystals, grains, and so on, he could not possibly arrive at the truth but got much closer than his contemporaries. For example, he maintained that quenching changed the structure of the metal without putting some "vital juices" from the water into the steel. He also put an end to the mythology about quenching agents (water, oil, blood,...) by pointing out that it is only their different ability to cool (we would call it different thermal conductivity) that was important.

Most remarkable, perhaps, he reasoned that the infusion of his “sulfurous and saline particles” made not only hard steel out of soft iron, but also hard and brittle cast-iron depending on how much of the stuff was infused. That is essentially correct. Cast-iron was very important for making cannons but also very dangerous because you tended to kill about as much of your own soldiers by exploding cannons made from the brittle stuff as enemy soldiers by getting the cannon ball over there. Malleable cast-iron, that actually could be cast, (in contrast to steel), would have been of utmost importance - but didn't exist.

Réaumur figured that one could make malleable cast-iron by taking some of the "sulfurous and saline particles" out of the ubiquitous brittle cast iron. He thus could be seen as the grandfather of the first "designer" steel. He even found a method to do so but (cover the cast-iron with some hard-to-get mysterious substance then know as "saffron of Mars") but (wrongly) considered that not to be practical, due to the rarity of the stuff. Much later in the 19th century, the “Réaumur process” was actually used on a large commercial scale because the mysterious reddish stuff turned out to be simple iron oxide or iron ore.

The next guy who must be mentioned in this context, is Torben Olof Bergman (1735-1784), a Swedish subject. Sweden was a major producer of iron and steel and used to be a superpower that liked to invade Germany, Denmark, Finland, Russia, and so on, until it was reduced to roughly what it is today in 1721.

Bergman, from Sweden's Uppsala University, published a book called "Dissertatio Chemica de Analysi Ferri" in 1781 (together with his Ph.D. student Gadolin; the book was essentially his thesis, it appears) in which he sought explanations for the different types of iron and steel in terms of the metal's chemical composition. He reasoned, not quite correctly, that only elements commonly found in the ore could be responsible for the changes in the metal: sulfur, plumbago, arsenic, zinc, and manganese. Note that "chemistry" in the modern sense was around the corner but that Lavoisier's seminal book was to appear 8 years later.

In contrast to Réaumur, who arrived at this conclusions by synthesis, by making steel, Bergmann's approach was analytical: look what is in there. That's why Bergmann is sometimes called the father of analytical chemistry.

Bergmann is sometime given credit for discovering that it is carbon that makes steel out of iron. To understand that we need to remember that "plumbago", while meaning lead (Pb) in principle, also was the name for graphite. In 1781 Bergman reported he had found that cast iron contained up to 3.3% of 'plumbago', steel contained up to 0.8% and wrought iron less than 0.2%. You can't do much better that that.

One of Bergmann's student was Carl Wilhelm Scheele mentioned above and by now the proto-science of iron and steel was well on its way.

Finally, in 1786, Gaspard Monge (1746 -1818), Charles Augustin Vandermonde (1727–1762) Claude Louis Berthollet (1748-1822) published major work that finally used the word carbon (actually "charbone") instead of "plumbago" or "sulfurous particles" and thus put an end to the basic question of what makes steel.

Well - not quite. While it became clear to the initiated that you could make steel by putting some carbon in otherwise pure iron, you could make steel in the sense of "hard iron plus something" also by many other means, e.g. with phosphorous. And hardness was only one important property. Just as important (and rather unclear) were properties like malleability, "cold shortness" and "red shortness", and just as much or even more work was spend on the questions coming up in this context.

Since even the late 17th /early 18th century scientists knew more about that than we you do at this stage; I'll stop now. Rest assured that the matter will come up again further down this Hyperscript.

Source: Iron, Steel and Swords Script

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