Study On Preparation Process Of High-purity Quartz Powder

High purity quartz powder is widely used in the semiconductor, fiber optic communications and optical glass industry and so on. High purity quartz powder require a higher silica content, The purity of the high purity quartz powder such as the preparation of the quartz crucible should be reached to99.99%. High-purity quartz powder is obtained from the purification of Quality quartz raw material. UNIMIM is the representative in the quartz powder purification technology. In this regard, our country started late, Only can be primary purified quartz powder.Foreign companies imposed the technology blockade about the quartz powder purification technology against our country. The domestic market is mainly dependent on imports. So the study of high-purity quartz powder purification process is very necessary,and Quartz powder purification technology has good market prospects.The selection of raw materials used in here is primary purified quartz powder. It is mainly from the following aspects studied the preparation of high-purity quartz powder.(1) Using a single acid treats quartz powder. Optional single acid is hydrochloric acid and oxalic acid, quartz powder is treated with different concentrations of hydrochloric acid, The results show that with the increase of the concentration of hydrochloric acid, the total content of impurities in the quartz powder gradually decreases,but it is reduced minor. The best results for the total amount of impurities in the quartz powder reduced to117.30ppm.20g·L-1oxalic acid solution is used to handle the quartz power. The total amount of impurities in the quartz powder from136.95ppm reduced to119.14ppm. The effect is Ineffective.(2)Using mixed acid treat quartz power.Using mixed acid I (hydrochloric acid+5%HF) handles quartz power. Considering the concentration of influencing factors, Select different concentrations of hydrochloric acid was mixed with5%HF mixed into a mixed acid Ⅰ to treat quartz powder, The results show that as the mixed acid in the hydrochloric acid concentration increases, the total content of impurities in the quartz powder is reduced. The total amount of the impurities in the quartz powder obtained from136.95ppm reduces to37.86ppm,which is a good result.Using mixed acid Ⅱ (oxalic acid+5%HF) treats quartz powder, Considering the concentration of influencing factors, Select different concentrations of oxalic acid and5%HF mixed into a mixed acid Ⅱ are treated quartz powder. The results show that as the mixed acid in the oxalic acid concentration increases, the total content of impurities in the quartz powder is reduced. The impurity content is reduced to36.69ppmwhich is a good result,too.Using a mixed acid Ⅲ quartz powder(15%hydrochloric acid10%nitric acid+5%HF) treat the quartz power. Considering the reaction time of influencing factors, the selected reaction time is8hours、2days、3days、5days、8days. The results show that with the extension of reaction time, the total amount of impurities in the quartz powder began to decrease, when arrives2days,the effect is not obvious. Therefore, the reaction time can be selected2days,the impurity content in quartz powder is33.95ppm.,the effect is significantly. Quartz powder is calcined at800℃for2hours,and invested the quartz power into the mixed acid Ⅲ in extreme time, Using acid treat it for8hours. The total amount of impurities in the quartz powder reduces to34.47ppm.Obtained with the simple acid treatment43.17ppm, the total amount of impurities further reduce.Using mixed acid Ⅰ (15%hydrochloric acid+5%HF) and mixed acid Ⅲ(15%hydrochloric acid+10%nitric acid+5%HF) treated quartz powder,then using mixed acid Ⅰ (20%hydrochloric acid+5%HF)and mixed acid Ⅲ(20%hydrochloric acid+15%nitric acid+5%HF) second treat the quartz power. Results of the total amount of impurities in the quartz powder is reduced to35.23ppm,30.24ppm, the effect is significantly. In the mixed acid treatment process, Quartz powder has a different degree of loss. This is mainly due to the mixed acid is added HF. HF would dissolve some of the quartz powder, this results in the loss of the quartz powder.(3) HCl treatment of high-purity quartz powder in high temperature. In a tube furnace, HCl gas was passed into the quartz powder in high temperature. Flow rate of the HCl is1L·min-1, which makes the quartz powder fluidizing up. The reaction temperature and reaction time are the considerations, Doing time and temperature factors analysis. Selecting temperatures are800℃,900℃,1000℃,1100℃,1200℃Selecting times are30min,60min,90min,120min.The results showed that the optimal treatment is1200℃and90min. But the capacity of the processing method of the high-temperature HC1is limited. The final content of impurities can only be reduced to55.56ppm.(4) Analysis the morphology of the quartz powder by a scanning electron microscope (SEM).Studying different purity quartz powder includes the quartz powder material, quartz power which after the acid treatment,the UNIMIM purity quartz powder and so on. Analysis the surface structure and morphology, The result shows that the purified quartz powder surface has uniform pits.(5) Designing the purification process of the quartz powder. Focuses on the design of mixed acid dip treatment after pickling process.It establishes a multi-stage countercurrent washing model. A different series of washing liquid to solid ratio is calculated by the model,at the same time, washed with pure water and washed with reservoir tanks are also calculated by the model. After comprehensive consideration, liquid to solid ratio is selected4:1,it needs9Series. uses pure water4.55t,the mass fraction of generate waste acid is41.44%.