Characteristics And Mechanism Of Extracting Germanium From Low Germanium Bearing Residue With High Silicon Content

Due to its excellent semiconductor and optoelectronic properties,Ge is widely used in optical fibers,optical imaging,catalysts,and electronics and solar energy.As an important strategic resource,few independent deposits exist.At present,Ge is mainly extracted from by-products such as zinc smelting slag and fly ash.On the other hand,although the research on the recovery of Ge from secondary resources has become more and more perfect,most of them focus on the recovery of Ge from low-Si content or si-free Ge-containing materials,and there is a lack of research on high-Si content Ge-containing materials.Although reports have confirmed that Si has an adverse effect on Ge leaching,there is a lack of research on high-Si materials,and there is no clear conclusion on the leaching behavior of Ge during sulfuric acid leaching and the mechanism of Si behavior on Ge leaching.Based on this,this paper takes the waste residue,low Ge bearing residue with high Si content produced in the Ge recovery process as the research object,and uses the sulfuric acid leaching process and the lime roasting-atmospheric sulfuric acid leaching process to investigate the leaching characteristics of Ge.The changes of morphology,particle size and phase of silica gel are revealed,and the influence mechanism of silica gel crystallization,polymerization,depolymerization and other reactions is revealed,in order to provide theoretical and technical support for the recovery of Ge from high Si content with Ge materials.The paper has important academic value and practical significance.The main conclusions of the study are as follows:The main components in the low Ge bearing residue with high Si content are Si（Si O₂content 44.87%）,Zn（5.98%）,Ge（2.75 kg/t）,the Ge content is high and has high economic value,but due to the high Si content,Recycling is difficult,so it is often treated as waste residue.The results of EPMA analysis show that Ge in the low Ge bearing residue with high Si content is closely related to the Si-containing phase,and Ge mainly forms Si-Ge co-precipitation or adsorption with silica gel,which is the reason why the Ge in the high-Si and Ge-containing material is present.An important reason for the difficulty in leaching.The experimental results of atmospheric acid leaching and high pressure acid leaching of low Ge bearing residue with high Si content show that the leaching temperature has the most significant effect on Ge leaching,and increasing the leaching temperature is beneficial to Ge leaching.When the leaching temperature increased from 90℃to 240℃,the leaching rate of Ge increased from 18.96%to 73.88%,and the Zn leaching was always about 80%,indicating that the occurrence states of Zn and Ge were different,and the influence of Si on Zn was small.The reason why temperature has a significant effect on Ge leaching is that in high temperature environment,high-polymer Si O₂ depolymerizes into oligomeric Si O₂,and at the same time,high temperature promotes the polycondensation of oligomeric silicic acid,and finally shows high activity and large specific surface area.The depolymerization and the generation of small specific surface,low activity and dense oligomeric Si O₂ lead to the dissociation of Ge in the Si-O network,and at the same time,the adsorption of Si to Ge is reduced,and the leaching of Ge is improved.Based on the knowledge of Si behavior during high pressure acid leaching,a study on the treatment of low Ge bearing residue with high Si content by lime roasting-atmospheric pressure sulfuric acid leaching process is proposed.When the molar ratio of calcium to Si is 0.3,the roasting temperature is 1000℃,and the initial acidity of sulfuric acid leaching is 120 g/L,the leaching rate of Ge can reach 70.1%,and the leaching rate of zinc is 77.9%.When the direct roasting-sulfuric acid leaching process is used,the leaching rate of Ge is less than 20%.In addition to the amount of lime,the roasting temperature has a more significant effect on the leaching of Ge.Similar to the high-pressure acid leaching process,the roasting process has little effect on the leaching of Zn.Only when the roasting temperature exceeds 1000°C,the zinc leaching rate decreases slightly.The lime roasting-atmospheric pressure acid leaching process can effectively improve the leaching effect of Ge.The reason is that adding Ca O in the roasting process can depolymerize the complex high-poly Si-O network,and the complex infinite tetrahedral structural units with high polymerization degree tend to be low-polymerized.tetrahedral single-chain structural transformation.With the transformation and depolymerization of the grid-like structure of the highly polymerized Si,the polymerization degree of the Si-O network in the residue decreases,and the Ge in the Si-O network is dissociated,thus facilitating the leaching of Ge.