Research On Iron Removal And Purification Process Technology Of Fused Silica

High-purity silica has a wide range of uses.Depending on the purity of the silica,it can be used in rubber,glass,ceramics,electronics,biology,optical fiber,military,aerospace,etc.At present,my country's silica purification process is still far behind foreign countries in the mid-to-high-end level,and is highly dependent on the acid leaching method.Exploring green and efficient high-purity silica impurity removal technology will greatly promote the development of my country's high-purity silica preparation process.The significance of research.In this paper,an process technology research on the beneficiation and purification of fused silica in the Donghai County,Jiangsu Province,has obtained the following r esults:The analysis of the properties of the raw material shows that,the XRD pattern shows the characteristic peaks of"steamed buns",indicating that the raw material is amorphous.In raw material,D₅₀=28.55?m,D₉₀=106.6?m,the raw material is dominated by flake silica,and the surface is relatively smooth,the SiO₂ content of the raw material is 99.89%,the main impurity is Fe₂O₃,and the Fe impurity content is 797.98mg/kg.In order to remove Fe impurities,the raw materials are sieved by a sieving machine,and the obtained raw materials with a particle size of 0.125mm-0.038mm are magnetically separated by LGS-1500 high-gradient magnetic separator.The raw materials are sieved by a sieving machine.The best magnetic separation conditions are:magnetic induction intensity of 1.2T,slurry concentration of 15%,under these conditions,the Fe impurity content of the raw ore drops to 271.30mg/kg.After the magnetic separation with Aspergillus niger culture liquid,the products continue to remove impurities.The results of single factor test and orthogonal test show that the best microbial leaching conditions are Aspergillus niger culture liquid p H 2.0,pulp concentration 5%,leaching time 12h,leaching temperature 35?;Under these conditions,the Fe impurity content of fused silica further drops to 128.21mg/kg,the Fe impurity removal rate is 83.93%,and the SiO₂ content increases to 99.96%.Using hydrochloric acid to mix oxalic acid and citric acid to chemically ex tract the products after magnetic separation,the best leaching conditions are:6.0mol/L hydrochloric acid+0.060mol/L oxalic acid+0.030mol/L citric acid,liquid-solid ratio 5:1,acid leaching The temperature is 100?and the acid leaching time is 9h;under these conditions,the Fe impurity content is reduced to 78.44mg/kg,the iron impurity removal rate is 90.17%,and the SiO₂ content is increased to 99.99%.Microbial leaching and mixed acid leaching of fused silica were analyzed separately for macro-kinetics,to explore the chemical reaction macro-kinetics and model fitting of biological acid,hydrochloric acid,oxalic acid and citric acid under different time conditions with respect to temperature fa ctors,and confirm that both leaching are similar It conforms to the internal diffusion control shrinking core model.In summary,the two purification processes of magnetic separation-microbial leaching and magnetic separation-mixed acid leaching can effectively remove impurities in fused silica,and the impurity removal rate can reach up to 79.35%.The paper has 32 pictures,38 tables,and 82 references.