Acheson Process Research Articles

Thermodynamic modeling of silicon carbide formation during the Acheson process in non-stoichiometric mixtures

A brief review and critical evaluation of the literature related to the mechanism of carbothermic reduction of silicon oxide is presented. To resolve the contradictions in the literature data about the number of chemical reactions and key intermediate substances during the Acheson process, thermodynamic modeling of products of carbothermic reduction of silicon (IV) oxide at 1 bar total pressure was carried out. It was determined that CO2 and Si were absent among the intermediates at temperatures close to the silicon carbide formation temperature (from 1520 to ~2500 °С). Out of several dozen possible reactions, the two dominant reactions that result in the formation of silicon carbide in the Acheson process were identified. The effect of reagents temperature from 1000 to 3000 °С, bulk and local deviation from stoichiometry of the initial mixture on the composition of the reaction products was discovered. Obtained new data explains some empirical observations and greatly simplifies the physicochemical modeling of the Acheson process.

Toward Sustainable Biomanufacturing: A Feasibility Index for Silicon Carbide Production from Rice Waste

Silicon carbide, known for its distinct chemical and physical properties, is increasingly recognized as a critical material in sectors such as energy, space, and defense. Traditional production methods like the Acheson process are energy-intensive and costly, both in terms of investment and maintenance. Additionally, the concentrated nature of its manufacturing can lead to supply bottlenecks, hindering technological progress in key areas. To address these issues, this paper proposes a circular economy approach to silicon carbide production, leveraging the ecological challenge of rice waste disposal to create a new source of silica materials. It includes an evaluation of the economic and technological feasibility of this method and introduces a multidimensional composite index to identify potential early adopters for large-scale implementation. This innovative approach not only reduces reliance on critical minerals but also offers a solution to managing agricultural waste.

Impurity formation mechanism of silicon carbide crystals smelted by Acheson process

Impurity formation mechanism of silicon carbide crystals smelted by Acheson process

Towards net zero emissions, recovered silicon from recycling PV waste panels for silicon carbide crystal production

The high rate of PV adaptation around the world requires a strategy for recovery of the materials from PV waste panels and a circular market development. In particular, the silicon recovered from the PV cells can be used in different applications. A valuable acquisition is to refine the recovered silicon at metallurgical grade to a high level of purity namely electronic grade silicon which in conjunction with graphite can be the raw material for silicon carbide crystal production. Based on a comprehensive and critical review of the latest research and development of relevant technologies, a manufacturing process is proposed to increase the usage of renewable resources, reduce the energy consumption and CO2e emissions. The recovered silicon from recycling PV waste can reduce the CO2e emissions to a third of what is involved in the current carbothermic reduction of quartz in an induction furnace. Based upon the thorough evaluation of available evidence, a continuous coupled process is envisaged where the upgraded metallurgical grade silicon from recycling PV waste undergoes further vacuum and gas refining to the electronic grade silicon. Then the purified liquid silicon enters a vertical Bridgeman furnace for silicon carbide crystal production through a bottom seeded solution growth process. Considering the silicon melting point at 1410 °C, omitting a solidification/ meting step after vacuum/gas refining leads to energy and material saving. The continuous method can reduce the CO2e emissions up to 75% compared with the current silicon carbide production through Acheson process.

Molten salt electrochemical upcycling of CO2 to graphite for high performance battery anodes

The efficient transformation of CO2 into a value-added material is a potential strategy to help mitigate climate effects caused by CO2 emissions. One potential CO2 conversion product is graphite which is an important and versatile material extensively used in many applications including as an anode for lithium-ion batteries (LIBs). Commercial graphite, however, is traditionally synthesized via the energy intensive Acheson process (>3000 °C) and the performance of such graphite can be limited under fast charging conditions which is important for vehicle electrification. Herein, we report the electrochemical transformation of CO2 to highly crystalline nano-graphite with a controlled microstructure in a carbonate molten salt at 780 °C. The use of a nickel foam electrode and controlled electrochemical parameters during the molten salt conversion process yielded pure graphite at a lower temperature compared to the Acheson process. Moreover, when investigated as an anode material for LIBs, the CO2-converted graphite exhibited high reversible capacity, long cycle life, and excellent rate capability even under fast charging conditions. This process provides a way to potentially reduce carbon emissions through the utilization of waste CO2 by converting it into value-added graphite suitable for fast charging, high-energy-density batteries for vehicle electrification.

Manufacture of SiC: Effect of Carbon Precursor

SiC is one of the most important ceramics at present due to its excellent properties and wide range of applications. The industrial production method, known as the Acheson method, has not changed in 125 years. Because the synthesis method in the laboratory is completely different, laboratory optimisation may not be extrapolated to the industrial level. In the present study, the results at the industrial level and at the laboratory level of the synthesis of SiC are compared. These results show that it is necessary to make a more detailed analysis of the coke than the traditional one; therefore, the Optical Texture Index (OTI) should be included, as well as the analysis of the metals that form the ashes. It has been found that the main influencing factors are OTI and the presence of Fe and Ni in the ashes. It has been determined that the higher the OTI, as well as the Fe and Ni content, the better the results obtained. Therefore, the use of regular coke is recommended in the industrial synthesis of SiC.

Prospective Life Cycle Assessment of Synthetic Graphite Manufactured via Electrochemical Graphitization

Lithium-ion batteries (LIBs) are expected to play a crucial role in meeting many of the clean energy-related goals. Due to its electrical properties such as good conductance, chemical inertness, and corrosion resistance, graphite is a very popular anode for LIBs. Traditional methods of producing battery-grade graphite (high purity >99%) include processing naturally mined graphite or manufacturing synthetic graphite via the Acheson process, which converts soft amorphous carbons such as petroleum coke into graphite by subjecting it to high temperature (up to 3000 °C) for prolonged periods of times (3–5 days). However, due to a lack of abundant high purity natural graphite sources, synthetic graphite is the preferred choice for many LIBs. A new synthetic electrochemical graphitization method that subjects the amorphous carbon precursor submerged in a molten salt mixture to a constant cathodic polarization (against a graphitic anode) has been discovered that has significantly lower graphitization temperatures (∼800 °C) and reduced graphitization time (3–6 h). Furthermore, the method can accept a higher variety of carbon precursors compared to the Acheson process. A prospective life cycle assessment (LCA) is conducted on this new method and compared against the traditional processes. The laboratory-scale demonstration of the method is used to build an inventory, which through various assumptions is scaled up to a commercial scale. An additional scenario is also considered with a biomass-derived carbon precursor for the graphite. The results from the LCA show that while the laboratory scale process is similar to the Acheson process and natural flake graphite in terms of impact, the scaled-up process is drastically better than the Acheson process in all environmental categories. Using a coconut shell-derived biomass precursor has a higher impact due to its manufacturing in Indonesia, as the Indonesian energy grid is highly fossil fuel dependent. Therefore, the biomass carbon may have a higher impact than petroleum coke dependent on the location of production of biomass-derived carbon black. The LCA has identified the molten salt─CaCl2─as a potential hotspot and suggests other salts should be considered. The new method shows promise in this early stage LCA in improving the environmental performance of graphite (and by relation LIBs) and therefore needs to be explored more in terms of its commercial viability.

Effect of Mesophase particles on the Electrographite carbon brush tribology behavior under no-load condition

Electrographite (EG) has partial electrical conductivity and is used as a current collector in direct current motors. EG is prepared from a suitable carbon source through a multi-step process to convert it to conductive carbon. In this work, EG was prepared with coal tar pitch (CTP) having different mesophase (MP) content (4, 8, 19, and 33%) and their characteristics were compared. The microstructural analysis of CTP indicated that increase in MP leads to increase in mesophase particle size. MP was found to have a significant impact on the physical and binding properties of CTP. X-ray diffraction studies showed EG to be a partially graphitized material with a degree of graphitization (DOG) ranging from 30% to 60%. Since coke-based materials graphitize more easily than lamp black, the DOG, crystal size, and d-spacing of coke-based material were higher. Graphitization in tube furnaces was better than induction and Acheson furnaces because of its concentrated heat in small size susceptor. The Design of Experiments (DOE) method with Face Centre Factorials was used to generate 14 different combinations of load (20 N,60 N, and 100 N) and velocity (1 m s−1, 3 m s−1, and 5 m s−1) for wear and COF analysis which were done on pin on disc apparatus. Response surface method (RSM) was used to investigate the relationship between wear, COF, and MP content. The CTP binder properties had a significant impact on wear. The COF decreased as the number of Brooks and Taylor structure MP particles increased. On the EG wear characteristics, adhesive wear was a more dominant factor than abrasive wear.

Occurrence forms of major impurity elements in silicon carbide

In this study, the forms of occurrence of impurity elements in silicon carbide (SiC) with different particle sizes were systematically investigated using a combination of X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-OES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The experimental results showed that in SiC powders prepared using the Acheson process, the contents of O, free-Si, free-C, and Fe impurities are high, and those of other trace impurity elements follow the order: Ti > Al > Ni > V. Moreover, O impurities mainly cover the SiC particle surface in the form of amorphous SiO 2 . Fe impurities exist around SiC particles as Fe 2 O 3 , Fe x Si y , Fe x Si y Ti z , and Fe x Al y Si z phases. Impurity elements are often introduced during the smelting of SiC and/or during milling or subsequent storage.

Engineering Graphitic Structure Via Molten Salt Assisted Low Temperature Electrocatalytic Graphitization for High Capacity Anode Application

Graphite, a successfully commercialized anode for lithium-ion batteries (LIBs), is conventionally synthesized via the Acheson process at ~3000 °C. Because of sluggish lithium diffusion kinetics, synthetic graphite exhibits abysmal electrochemical performance under fast-charging conditions, which is an essential prerequisite for boosting electric mobility. Herein, we demonstrated engineering the graphitic structure via molten salt assisted electrocatalytic graphitization of amorphous carbon feedstocks to afford nano-flake graphite with tunable interlayer spacing to accelerate lithium diffusion kinetics at ~800-850 °C. The beauty of our strategy for engineering the graphitic structure is that it results in high-performing nano- flake graphite at much lower temperature with a short synthesis time, resulting in a significant increase in energy savings. The resulting graphite with unique nanoarchitecture exhibits outstanding electrochemical performance at fast charging conditions and outscored state of the art’s commercial graphite. The results demonstrated that such a strategy could enhance the energy density of fast-charging batteries that could boost electromobility.

Low-Cost Transformation of Biomass-Derived Carbon to High-Performing Nano-graphite via Low-Temperature Electrochemical Graphitization

Graphite, an essential component of energy storage devices, is traditionally synthesized via an energy-intensive thermal process (Acheson process) at ∼3300 K. However, the battery performance of such graphite is abysmal under fast-charging conditions, which is deemed essential for the propulsion of electric vehicles to the next level. Herein, a low-temperature electrochemical transformation approach has been demonstrated to afford a highly crystalline nano-graphite with the capability of tuning interlayer spacing to enhance the lithium diffusion kinetics in molten salts at 850 °C. The essence of our strategy lies in the effective electrocatalytic transformation of carbon to graphite at a lower temperature that could significantly increase the energy savings, reduce the cost, shorten the synthesis time, and replace the traditional graphite synthesis. The resulting graphite exhibits high purity, crystallinity, a high degree of graphitization, and a nanoflake architecture that all ensure fast lithium diffusion kinetics (∼2.0 × 10-8 cm2 s-1) through its nanosheet. Such unique features enable outstanding electrochemical performance (∼200 mA h g-1 at 5C for 1000 cycles, 1C = 372 mA g-1) as a fast-charging anode for lithium-ion batteries. This finding paves the way to make high energy-density fast-charging batteries that could boost electromobility.

Определение эффективной температуры обработки углеродных материалов в высокотемпературных печах по параметрам спектроскопии комбинационного рассеяния образцов-свидетелей

The aim of this work is to evaluate the use of Raman spectroscopy of carbon fibre-based (CF) reference samples for establishing the heat treatment temperature (HTT) in high-temperature (1000 – 3000 °C) furnaces used in production of a series of carbon materials. Based on obtained correlational relationships between Raman spectroscopy parameters and HTT, the use of the ID/IG parameter is suggested for obtaining the most exact and reproducible results. An experimental basis for the use of polyacrylonitrile-based (PAN) CF as reference specimens is provided. It is shown that for PAN-based CF samples treated in the high temperature interval (1000 – 3000 °С) the ID/IG parameter correlates well with X-Ray diffraction analysis parameters. A series of Raman spectroscopy of reference specimens potential uses the in determination of effective HTT of carbon materials in technological processes of production of carbon-carbon based composite materials, artificial graphites and PAN-based CF’s and in the determination of temperature fields of laboratory and industrial equipment for high-temperature treatment of carbon materials in the temperature interval 1000 – 3000 °C, specifically Tamman, vacuum electric resistance and Acheson furnaces, are examined.

The Production of Silicon Carbide and Achievements in the Field of Furnace Gases Collection and Purification

Silicon carbide is obtained in ore-thermal furnaces by reduction of silica (quartzite) with carbon. The use of silicon carbide in the production of technical silicon as a carrier of the target element and as a reducing agent can significantly improve the technical and economic performance (TEP) melting. The process of reducing silicon melting in electric furnaces takes place in two stages. First, silicon carbide is formed as a pseudomorphosis over the carbon of the reducing agent, then silicon carbide interacts with silicon oxide to form elementary silicon. Physical and chemical properties of silicon carbides obtained with the use of various reducing agents were studied. The reducing potential and reaction ability of carbides depends on how their surface is developed. Carbide volume and density characteristics are obtained on the matrices of charcoal and petroleum coke. For comparison, data for carbide obtained in the Acheson furnace are presented. Measurements of relative electrical resistivity of the reducing agent were performed and obtained on the carbides basis with temperature in the range of 700–1700∘C. For comparison, the RER values of silicon carbide obtained in the Acheson furnace are given, the resistance of carbides is several times higher than the RER of the corresponding reducing agents, which favorably affects the furnaces smelting silicon electric mode. As a result of the silicon carbide addition to the charge, the power of the arc discharge increases and the intensity of the reduction process increases.
 Keywords: silicon carbide, gas cleaning dust, gas capture system

Effect of arc current on SiC fabrication from rice husk ash and diatomite in electric arc discharge furnace

AbstractSilicon carbide (SiC) was synthesized from Vietnamese rice husk ash and diatomite via the Acheson process in a graphite electric arc furnace. In this type of furnace, arc current generates temperature and therefore effect on the formation of SiC. The influence of arc current at 100, 150 and 200 A was investigated. Scanning electron microscopy and energy dispersive spectroscopy, XRD and Raman spectroscopy were performed to analyze the formation of SiC materials. Results showed the weight percentage of SiC in the synthesized product increased as the arc current increased.

Ambient Temperature Graphitization Based on Mechanochemical Synthesis

AbstractGraphite has become a critical material because of its high supply risk and essential applications in energy industries. Its present synthesis still relies on an energy‐intensive thermal treatment pathway (Acheson process) at about 3000 °C. Herein, a mechanochemical approach is demonstrated to afford highly crystalline graphite nanosheets at ambient temperature. The key to the success of our methodology lies in the successive decomposition and rearrangement of a carbon nitride framework driven by a denitriding reaction in the presence of magnesium. The afforded graphite features high crystallinity, a high degree of graphitization, a thin nanosheet architecture, and a small flake size, which endow it with superior efficiency in lithium‐ion batteries as an anode material in terms of rate capacity and cycle stability. The mild and cost‐effective pathway used in this study could be a promising alternative for graphite production.

Ambient Temperature Graphitization Based on Mechanochemical Synthesis.

Graphite has become a critical material because of its high supply risk and essential applications in energy industries. Its present synthesis still relies on an energy-intensive thermal treatment pathway (Acheson process) at about 3000 °C. Herein, a mechanochemical approach is demonstrated to afford highly crystalline graphite nanosheets at ambient temperature. The key to the success of our methodology lies in the successive decomposition and rearrangement of a carbon nitride framework driven by a denitriding reaction in the presence of magnesium. The afforded graphite features high crystallinity, a high degree of graphitization, a thin nanosheet architecture, and a small flake size, which endow it with superior efficiency in lithium-ion batteries as an anode material in terms of rate capacity and cycle stability. The mild and cost-effective pathway used in this study could be a promising alternative for graphite production.

DEVELOPMENT OF ENERGY-EFFICIENT AND ENVIRONMENTALLY FRIENDLY LININGS AND THERMAL INSULATION OF ELECTRODE PRODUCTION FURNACES

A numerical analysis of the thermoelectric state of the Acheson furnace was performed and the use of new thermal insulation of blanks that are graphitized was proposed. The expediency of using a single-component heat-insulating charge as thermal insulation is shown. In this case, in comparison with the use of a traditional multicomponent synthetic mixture, not only a decrease in the temperature of the blanks is observed, but also a significant equalization of temperature along the axis of the blanks. Based on the results of measuring the thermophysical properties and numerical simulation of temperature fields in the volume of the Acheson graphitizing furnace, a resource-saving and environmentally efficient carbon heat-insulating mixture was selected, which consists of raw and graphite coke grains 50/50 % (wt.) up to 2 mm in size. Theoretical and experimental studies of the ecological state of kilns and graphitizing furnaces have been carried out. Based on the analysis of the obtained experimental data, the temperature and time dependences of the concentration of carbon monoxide in kilns and graphitizing furnaces are established. The main sources of carbon monoxide formation are determined: under-oxidized carbon materials, aromatic and resinous substances of binder preforms. A set of measures has been developed that can reduce the concentration of carbon monoxide emissions from furnace equipment in industrial conditions. Experimental studies were carried out to determine the temperature dependence of the concentration of carbon monoxide during heating of a multicomponent and one-component heat-insulating charge, which made it possible to establish a reduction in CO emissions by more than 20 % in the case of using the proposed one-component charge. Bibl. 17, Fig. 9, Tab. 3.

Silicon carbide formation by carbothermal reduction in the Acheson process: A hot model study

A hot model study was done to investigate the progress of SiC formation via carbothermal route in the Acheson process. Experiments were carried out in a parametrically controlled medium-scale resistance furnace with the raw materials (silica and carbon) in the stoichiometric ratio. The morphological analysis of the formed product at different radial and angular locations was carried out by XRD and SEM. Whereas, the chemical analysis was used to analyze the sample quantitively which gave a radial and angular map of the amount of SiC formation. The temperature measurement at various locations indicates that it has a significant influence on SiC formation. Whereas, the stoichiometric disorder in the product showed the loss of carbon in the process and silica impurity in the formed SiC. The Porosity measurement shows strong variation from the center to the periphery. The results of this study would be beneficial for the current mass production of SiC.

Temperature measurements in a laboratory scale furnace for manufacturing of silicon carbide through Acheson process

A hot model for SiC production has been developed on the laboratory-scale to measure temperatures in harsh conditions at various locations of the furnace. A unique method has been adopted to measure the core temperature in reactive and high temperature environment. The temperatures of the core and at various radial and angular locations within the furnace were measured using a ratio pyrometer and by B and C-type thermocouples respectively; this type of controlled measurement is missing in this field. In this study, the power supply was maintained such that a constant core temperature was sustained. The temperature decrease along the radial direction is an indicative of the SiC production. Further, at the same radial distances, variations in the local temperature depended on the angular positions; upper regions showed higher temperatures due to escaping hot gases. The results obtained in this study are expected to be beneficial to the industries.

Optimization of processing parameters for graphitization of oil palm trunk waste at lower heating temperature

Previously synthetic graphite was produced at higher temperature which is around 2,500 °C in complex processing method. The method bear the name of the scientist whose discover the synthetic graphite namely “Acheson Process”. However, via pyrolysis process, in controlled heating condition, and specific heating rate by utilizing oil palm trunk waste, synthetic graphite was managed to produce at much lower heating temperature. In this research, the heating temperature were varied in the range of 500 °C, 800 °C, and 1,000 °C. The heating rate applied also varied, from 5 °/min to 10 °/min and 20 °/min. After heating treatment, the samples were characterized using X-ray Diffraction (XRD) and analysed by X’Pert Highscore Plus software. Graphitic nature of the synthetic graphite produced was further supported by RAMAN analysis. The morphological study was carried out by using Scanning Electron Microscope (SEM). Based on the analysis, optimum processing parameters was optimized. It is at the temperature of 800 °C and at the heating rate of 20 °/min.