China Nonferrous Metallurgy

Gallium is regarded as a crucial material for modern new energy and high-tech industries, with a growing demand. China's low rank coal reserves are abundant and associated with gallium metal, but China's low rank coal has the characteristics of high carbon-silicon content and low gallium content, which makes gallium leaching interference great, resulting in low leaching rate and difficult gallium separation. In this paper, a pretreatment process for the removal of carbon elements from low rank coal by Budor reaction is proposed, and on the basis of characterization analysis, TG-DSC analysis is carried out, and a single factor test of the CO₂ gasification and decarburization process of low rank coal is carried out, and the following main conclusions are obtained. The chemical composition of low rank coal is mainly carbon, oxygen, aluminium, silicon, gallium content is 13μg/g, and the main phase structure is kaolinite, quartz, calcite, hematite and organic matter. The mass loss of low rank coal in Ar atmosphere is about 29%, while the mass loss in CO₂ atmosphere is more than 75%, which is attributed to the Budor reaction in CO₂ atmosphere. Under the optimal decarburization conditions of 1100℃, 60minutes and CO₂ gas flow of 5L/min, the decarburization rate of low rank coal can reach 90.43%, and the gallium content is increased from 13μg/g to 99μg/g, which is 6.6 times enriched. In this method, the CO₂ waste gas generated in the industrial production process is used to convert the carbon resources that are difficult to be directly utilised in low rank coal into gas energy CO that is easy to collect and utilise, and the effective enrichment of gallium in low rank coal is realised.