Study On Impurity Removal In Ppm Level Of Domestic Quartz Sand To Replace Crystal Sand

High purity quartz sand is the only raw material for preparing high-grade quartz glass instead of crystal.In recent decades,with the progress of high technology and the popularization of 5G,the preparation technology of high-purity quartz sand instead of crystal sand has been paid more attention due to the depletion of global industrial crystals.However,the technology of preparing high-purity quartz sand has been monopolized by a few foreign enterprises,which is not only expensive,but also limited to China’s import.Therefore,it is of great strategic significance and application value to explore the technology of preparing high-grade quartz glass by using domestic high-purity quartz sand instead of crystal sand,especially the research of removing ppm impurities in quartz sand.This paper mainly does the following work:1.Study on optimization of experimental ore source.The study on the preparation of high purity quartz sand from quartz ores in Donghai,Jiangsu,Qichun,Hubei and Kuqa,Xinjiang shows that the quartz ore in Donghai,Jiangsu has the highest light transmittance and the highest liquid phase density of H₂O in gas-liquid inclusions is 0.825,which is more suitable for the high frequency electromagnetic wave impurity removal technology adopted in this paper.2.The effect of heating temperature and time on the removal of ppm gas-liquid inclusions in quartz sand was investigated through the study of high frequency electromagnetic wave removal of ppm impurities in quartz sand.Fourier transform infrared spectrometer and other measuring instruments were used to characterize the experimental products.With the increase of heating temperature and time,the content of ppm gas-liquid inclusions dominated by hydroxyl groups in quartz sand gradually decreased and the light transmittance increased.The content of ppm gas-liquid inclusions remained unchanged above 1000℃,but remained stable after 45min.The optimum technological parameters for removing ppm gas-liquid inclusions in quartz sand are high frequency electromagnetic wave temperature 1000℃and heating time 45min.The light transmittance increased from 54.3%to 84.7%,and the total content of gas-liquid inclusions decreased from 331.27 ppm to 123.55 ppm.3.The quartz sand was treated by high frequency electromagnetic wave+mixed acid acid leaching,and it was determined that high frequency electromagnetic wave+acid leaching could further remove metal impurities such as Fe and Al in quartz sand.The optimum process is as follows:holding the temperature in a high frequency electromagnetic wave furnace at 900℃for 30min,then passing HCl,HNO₃and H₂SO₄with a concentration of 5mol/L and a ratio of 1:1:2,the acid leaching time is 2h,the acid leaching temperature is 90℃,and the liquid-solid ratio of mixed acid and quartz sand is 5:1.The results of ICP-MS showed that the content of Fe impurity decreased from 102.73μg/g to 2.16μg/g,and the removal rate was 97.8%;The content of Al impurity decreased from153.21μg/g to 16.44μg/g,and the removal rate was 89.3%.The results of XRD showed that the contents of metal impurities in quartz sand,especially Fe and Al,could be further reduced,which indicated that the research of high frequency electromagnetic wave+mixed acid leaching technology could effectively remove metal impurities in quartz sand.