Characteristics,Forming Conditions And Mineralogy Of Yanjin Quartz Sand In Yunnan Province

In this paper,we have carried out secondary development of the existing data and studied the metallogenic geological background,distribution regularities and metallogenic mechanisms of the Yanjin quartz deposit in Yunnan by means of remote sensing,mineral petrology,elemental geochemistry and fluid inclusions.On this basis,summarize the conditions of high purity quartz(>3N)ore formation.A purification process test was conducted to determine the quartz purification technology suitable for the area,and the development environment and utilization prospects of the quartz mine in the area were comprehensively evaluated.The identification of thin sections and scanning electron microscopy-energy spectrum analysis showed that the impurities of quartz sand in the Yanjin area are mainly classified into two types: intergranular and intragranular impurities.The intergranular impurities are ferrous minerals,siliceous cements,clay minerals,and altered minerals.Mainly;intragranular impurities are mainly heavy minerals such as tourmaline,zircon,rutile,and gas-liquid inclusions.Particle size statistics show that the quartz particle size is concentrated in0.1～0.4mm,the sorting coefficient(So)is less than 2,and the sortability is good.The analysis of cumulative probability curves shows that the diagenetic particles of this group of quartz sandstones are mainly transported by traction and hopping,contain very few particles for suspension transport,and have an overall skewness of >1 and a typical coastal sedimentary environment.Electron-probe experiments revealed that there are sphalerite,pyrite,apatite,mica,montmorillonite,talc,and other impurity minerals in the quartz sandstone ore,and targeted purification experiments for different impurity minerals are needed.Pure quartz sand can be obtained after calcined water quenching,ultrasonic cleaning,magnetic separation and pickling.After ultrasonic cleaning,the content of aluminum was reduced from 0.0974% to 0.0502%,the overall cleaning effect was close to 50%,and the cleaning effect of some samples reached 80%,the iron impurity content after magnetic separation was reduced from 0.2798% to 0.0541%,and the clearance rate was greater than 80%.The sample removal rate is as high as 95%,and the removal effect is obvious.After the final pickling,the removal rate of various impurity elements exceeds 90%,and the purity of the quartz can reach 99.5% or more.The results of quartz deep processing experiments show that the purified quartz sandstone still contains black particles that cannot be removed.This type of impurities affects the purification effect,resulting in a darker color of the processed quartz glass.The synthetic evaluation shows that this kind of quartz ore is only suitable for the preparation of ordinary glass.