Beneficiation and Purification of Diou Quartz

　　Quartz, also known as silica, is a common non-metallic mineral raw material, which has a wide range of applications. China's quartz mineral processing, purification and deep processing development and utilization are relatively late, and mainly used in the construction industry, glass manufacturing, ceramic industry and foundry industry. One common feature of these areas is the large demand for quartz and the low quality requirements of raw materials.

　　At present, the quartz sand dressing and purification technology in the United States is the most advanced in foreign countries, characterized by large industrial output, high degree of equipment specialization and production automation, and its products have developed to the sixth generation (total impurity content is less than 8 x 10-6, transparency is optical grade). High-purity and ultra-high-purity quartz sand made by mineral processing has been widely used in aerospace, atomic energy technology, laser, optical cable communication, military and other high-tech fields. With the progress of science and technology, the demand for high-tech silicon will increase greatly, and the depletion of natural crystal resources makes people have to turn their attention to the substitutes of natural crystal - high purity and ultra-high purity quartz. Therefore, actively exploring and promoting the progress of quartz mineral processing and purification technology, realizing the cost of refined quartz, high-purity and ultra-high-purity quartz, mass industrial production, to make up for the shortage of natural crystal resources, meet the needs of high-tech silicon has important practical significance.

　　II. METHODS FOR PURIFICATION OF QUARTZ CONCENTRATION

　　Purification of quartz sand is a highly difficult separation technology to remove small or trace impurities from quartz and obtain refined quartz sand or high purity quartz. In recent years, research on quartz purification technology at home and abroad mainly focuses on the following aspects:

　　(1) Water washing and grading desliming

　　The grade of SiO 2 in quartz decreases with the grain size of quartz, while that of magazine minerals such as iron and aluminium is on the contrary. This phenomenon is particularly evident in quartz containing a large amount of clay minerals. Therefore, it is very necessary to separate quartz ore by water before it is selected, and the effect is obvious. For example, the chemical composition of the raw quartz ore of Malingshan ore in Suqian, Jiangsu Province is 79.38% of SiO 2, 1.68% of FeO 2 and 311.28% of ALO 2. The content of -0.1mm grain size is 27.65%. After washing and desliming, the grade of SiO 2 rises to 86.36%, FeO 3 decreases to 0.49%, and ALO 3 decreases to 6.79%. The effect of removing impurities and purifying is remarkable. As a pretreatment method before ore separation, water washing and grading desliming have been widely used for a long time, but the removal effect of thin film iron and adhesive impurity minerals on quartz surface is not significant.

　　(two) scrubbing

　　Scrubbing is to use mechanical force and abrasive force between sand grains to remove the film iron, bonding and muddy impurity minerals on the surface of quartz sand and further crush the mineral aggregates that have not become monomers, and then achieve the effect of further purification of quartz sand through grading operation. At present, there are two main methods: rod friction washing and mechanical scrubbing. For mechanical scrubbing, it is generally believed that the main factors affecting the effect of scrubbing are rod friction washing and mechanical scrubbing. If it comes from the structure characteristics and configuration of the scrubber, followed by technological factors, including scrubbing time and scrubbing concentration, the research shows that the scrubbing concentration of placer is the best between 50% and 60%, and to a certain extent, it increases the difficulty of quartz purification; in principle, the scrubbing time should not be too long, because the scrubbing time is too long, it will increase. Equipment wear, increase energy consumption and increase the cost of mineral processing and purification. Because of the unsatisfactory effect of mechanical scrubbing for some quartz ores, the application of rod scrubbing industry in China is relatively common and mature. If a quartz raw ore in a certain area is washed by water and desliming by stages and then scrubbed by rods with more than 0.3mm quartz sand, the results show that after scrubbing by grinding, Fe2O3 decreases from 0.19% to 0.10%, and iron removal rate reaches 47.4%. We used high-efficiency and strong scrubbing of quartz in Yunnan with appropriate technology and equipment. The results showed that the effect of rod scrubbing was better than that of rod scrubbing. The yield of rod scrubbing was 49%, while the recovery of high-efficiency and strong scrubbing was 73%. The purpose of dosing is to increase the electric repulsion force on the surface of impurity minerals and quartz particles, and to enhance the separation effect between impurity minerals and quartz particles.

　　(three) magnetic separation

　　With the application of magnetic separation technology, weak magnetic impurities such as hematite, limonite and biotite can be removed to the maximum extent. Wet high intensity magnetic separator or or high gradient magnetic separator are usually used in high intensity magnetic separation. Generally speaking, quartz with weak magnetic impurities such as limonite, hematite and biotite can be selected by wet high-intensity magnetic machine above 10000 Oster. For strong magnetic minerals with impurities such as magnetite, weak magnetic machine or medium magnetic machine is better. Shangcun Hongtian Yuanping uses high-intensity magnetic machine to carry out experimental conditions on Seto quartz sand. The results show that magnetic separation number and magnetic field intensity have important effects on iron removal. With the increase of magnetic separation times, iron content decreases gradually, and most iron can be removed under certain magnetic field intensity. However, even if the magnetic field intensity increases a lot, the iron removal rate will not change much. In addition, the finer the grain size of quartz sand, the better the iron removal effect. The reason is that the amount of iron-containing impurities in fine quartz sand is high. When there are many impurity minerals in quartz sand, it is impossible to purify quartz sand into high-purity sand only by scrubbing, desliming and magnetic separation. In order to further improve the purity of quartz and reduce impurities.

　　(four) flotation

　　Considering the serious impact of fluorine-containing wastewater on the environment, foreign countries appeared in the 1970s.