Experimental Study On Preparation Of High Purity Quartz Sand

High purity quartz sand has been regarded as a kind of strategic resources.The applications involve all kinds of high and new technology industries,such as semiconductor,solar energy and so on,the demand of high purity quartz is growing and the reserve of crystal which is regarded as the raw material of high purity quartz sand is dwindling.Quartz sand can be used as a substitute for crystal providing support to the materials of the new and high technologies.Therefore,it is of great significance to exploration the purification technology of quartz sand.In this study,processes such as crushing,roasting,water quenching,shattering,magnetic separation,flotation and acid leaching are explored on quartz ore from a plant of Jiangsu for purification experiment.Process mineralogical research shows that the quartz of the ore is xenomorphic crystal,inequigranular texture,and block structure.The main mineral impurities are mica,feldspar,and limonite and the grade of Si O2 is 99%,the content of the total impurities is more than 500μg/g,mainly Fe,Al,Ti.which is 178.2μg/g,152.6μg/g,22.5μg/g,respectively.Roasting-water quenching treatment can obviously reduce the hardness of the sample,the best roasting condition is at the temperature of 900℃ for 2h.The experiment of shattering is conducted between the roll crusher and planetary mill on granularity processing,their qualified grade(0.1mm~0.3mm)content are 60.98% and 44.11% respectively.For a high-gradient magnetic separation at fine steel rods as magnetic medium in the magnetic field strength of 1.7 T,the result shows the contents of Fe and Ti drop down to 61.3μg/g and 1.4μg/g,respectively.A further floatation test is preformed at the inhibitor dosage of sodium silicate is 600g/t and collector dosage of DDA is 1200g/t at the pH of 2.5~3,the contents of Fe and Al fall from 61.3μg/g and 145.4μg/g to 33.3μg/g and 95.3μg/g,respectively.The acid leaching of flotation concentrate is conducted at the concentration of mixed acid of 50%,which contains H2SO4:HCl:HNO3:HF=10:5:3:1,a ratio of 20 g sample for 40 ml acid liquor at 70℃ for 2h,the content of Li,Na,K drops to 0.7μg/g,7.8μg/g,4.0μg/g from 1.4μg/g,48.3μg/g,50.9μg/g respectively.Fe,Al,Ti content fells to 4.1μg/g,12.1μg/g,0.8μg/g respectively,and the high purity quartz of total impurities as low as 37.2μg/g are acquired.The micrographs of the ore and final product show the surface becomes very rough,and forms rich cracks after these processes.Further analysis of thermodynamics,HF has the best effect of making these impurities dissolve,so is with the quartz.