碱熔活化—酸浸新工艺提取褐煤灰中的锗OA

Germanium in lignite ash mainly exists in Ge—O—Si bonded state,vitreous encapsulated state and iron oxide adsorbed state.The traditional acid leaching method is difficult to destroy the structure of highly stable Ge—O—Si bond and dense encapsulated vitreous body,resulting in less than 50％germanium leaching rate and low resource recovery rate.Based on the comparison of three process routes of lignite ash direct acid leaching,roasting-acid leaching,alkali fusion activation-acid leaching and two leaching systems of sulfuric acid or hydrochloric acid,the process route of extracting germanium from lignite ash by high temperature alkali fusion pretreatment-acid leaching process was proposed and studied.The effects of alkali fusion temperature,mass ratio of material to alkali and alkali fusion holding time on the leaching rate of germanium in lignite ash were investigated,and the leaching effects of sulfuric acid and hydrochloric acid on alkali fusion activation products were compared.The results show that the leaching performance of germanium can be significantly improved by breaking the Ge—O—Si bond by alkali fusion and converting insoluble silicate into soluble sodium salt,and then the efficient leaching of germanium can be realized by conventional acid leaching.Under the conditions of alkali fusion temperature of 600℃,mass ratio of material to alkali of 1/1.8 and alkali fusion time of 1 h,the main spherical structure of lignite ash is destroyed,and the encapsulated substances in alkali fusion products are released.When hydrochloric acid or sulfuric acid leaching systems are used,the leaching rates of germanium are 86.37％and 93.98％,respectively.This technology can realize the efficient leaching of germanium in lignite ash,which can provide a new technical approach for the resource utilization of high-silicon germanium-containing secondary materials and the efficient recovery of strategic metal germanium.