Artificial graphite from Shubarkol coal obtained by sublimation of carbon atoms into the gas phase followed by desublimation into high-purity graphite

Abstract

This article discusses a plasma-chemical method for producing high-purity graphite from an air suspension of low-ash coal particles from the Shubarkol deposit in Kazakhstan. The technological process is based on the ability of carbon to transform from a solid to a gaseous state, bypassing the liquid state. This means it sublimes at high temperatures and desublimes as the temperature of the gaseous medium in the reactor zone decreases. The use of a graphite catalyst allows for controlled formation of the graphitized material. Atomic carbon graphitization occurs over a wide temperature range. It was established that graphite obtained in high-temperature reactor zones is purer than graphite obtained in reactor zones close to 500°C. This feature of the graphitization process enables product classification by quality. The design of a reactor based on sublimation and desublimation processes for graphite production is discussed. The use of a high-frequency electromagnetic zone in the plasma-chemical reactor design allows for controlled graphitization of atomic carbon, intensifying desublimation processes over a graphite powder catalyst. The plasma-chemical apparatus design includes a dust collection system and carbon monoxide neutralization, which can occur due to variations in the component proportions in the feedstock, which includes carbon powder, graphite powder catalyst, and carbon dioxide. The developed apparatus can be used to produce a sorbent – thermochemically expanded graphite – from graphite by varying the operating mode. The aim of this research is to develop a plasma-chemical technology for producing graphite from coal based on sublimation and desublimation processes in a single reactor, with the separation of impurities during the graphitization of carbon atoms over a graphite catalyst.