Quartz is the second most abundant mineral in the continental crust, second only to feldspar. There are many types of quartz, and colorless and transparent quartz is called crystal. Quartz sand purification refers to the removal of small or trace impurities in quartz through highly difficult separation technology to obtain refined quartz sand or high-purity quartz.
01Washed
The grade of SiO2 in water-washed and graded desilted quartz decreases with the fineness of the quartz particle size, while the grade of magnesium minerals such as iron and aluminum is just the opposite. This phenomenon is especially obvious in quartz containing a large amount of clay minerals. Therefore, when sorting It is very necessary to wash and grade the quartz raw ore before desliming, and the effect is obvious.
For example, the chemical composition of quartz raw ore from a certain mineral processing plant is: SiO279.38%, Fe2O31.68%, AL2O311.28%, and its particle size composition has a -0.1mm particle size content of 27.65%. After pre-selection, washing and classification desliming, SiO2 The grade is increased to 86.36%, Fe2O3 is reduced to 0.49%, and AL2O3 is reduced to 6.79%. The impurity removal and purification effect is relatively significant.
Water washing and graded desliming have been used earlier and more commonly as pretreatment methods before mineral processing, but their removal effect on thin film iron and adhesive impurity minerals present on the quartz surface is not yet significant.
02 scrubbing
Scrubbing uses mechanical force and abrasive peeling force between sand grains to remove thin film iron, adhesive and muddy impurity minerals on the surface of quartz sand, and further scrubs out non-monomer mineral aggregates, and then further refines the quartz sand through grading. purification.
At present, there are two main methods of bar cleaning: friction cleaning and mechanical scrubbing. For mechanical scrubbing, it is generally believed that the factors that affect the scrubbing effect mainly come from the structural characteristics and configuration of the scrubbing machine, followed by process factors, including scrubbing time and scrubbing concentration.
Research shows that the scrubbing concentration is best between 50% and 60%. The scrubbing time is in principle based on the preliminary product quality requirements and should not be too long to avoid reducing grinding energy consumption and increasing mineral processing and purification costs. For example, in a certain place, quartz sand with a diameter of over 0.3mm after washing, classification, and desliming was subjected to rod friction and scrubbing. The results showed that after grinding and scrubbing, Fe2O3 was reduced from 0.19% to 0.10%, and the iron removal rate reached 47.4 %.
03Magnetic separation
The magnetic separation process can remove hematite, limonite, biotite and other weak magnetic impurity minerals to the maximum extent, including conjoined particles. Intensive magnetic separation usually uses wet strong magnetic separator or high gradient magnetic separator.
Generally speaking, for quartz whose impurities are mainly limonite, hematite, biotite and other weak magnetic impurity minerals, a wet strong magnetic machine with a temperature above 10.000 Oersted can be used for sorting; for quartz whose impurities are mainly strong magnetic minerals For quartz, it is best to use a weak magnetic machine or a medium magnetic machine to sort it.
Tests have shown that the number of magnetic separations and the strength of the magnetic field have an important impact on the iron removal effect. As the number of magnetic separations increases, the iron content gradually decreases. Under a certain magnetic field strength, most of the iron can be removed, but after that, even if the magnetic field strength There is a lot of increase, and the iron removal rate does not change much. In addition, the finer the particle size of quartz sand, the better the iron removal effect is. The reason is that the content of iron-containing impurity minerals in fine-grained quartz sand is high.
04 Flotation
Considering the serious impact of fluoride-containing wastewater on the environment, the fluoride-free acid flotation method appeared in the 1970s. For example, in Japan, in the separation of feldspar and quartz, sulfuric acid or hydrochloric acid (PH=2) is used to mix the slurry, and high-grade fatty amine salt and sodium petroleum sulfonate are added as mixed collectors to successfully achieve flotation. The fluorine-free and acid-free flotation method is a new technology for quartz-feldspar flotation and separation that has been vigorously developed in recent years. By increasing the flotation ratio, feldspar is preferentially flotated and the separation of the two is achieved. However, the fluorine-free and acid-free flotation method is not as mature as the HF method and the acid method, and there are no reports of industrial production and application. Mica and quartz have similar isoelectric points, making separation difficult. Or use two methods of flotation, anionic and cationic collectors, under alkaline conditions, both of which can achieve good results. Generally speaking, after scrubbing, desliming, magnetic separation, and flotation, the purity of quartz can reach 99.3%-99.9%, which basically meets the needs of industrial sand.
05Acid leaching
Acid leaching takes advantage of the fact that quartz is insoluble in acid (except HF). Other impurity minerals can be dissolved by the acid solution, thereby further purifying the quartz. Commonly used acids in acid leaching include sulfuric acid, hydrochloric acid, nitric acid and hydrofluoric acid; reducing agents include sulfurous acid and its salts. Research has found that the above acids have good removal effects on non-metallic impurity minerals in quartz, but the effect on different metal impurities, acid types and concentrations is not obvious. It is generally believed that various dilute acids are effective in removing Fe, Al has obvious effects, while concentrated sulfuric acid, aqua regia or HF acid leaching is more effective in removing Ti and Cr. A mixed acid composed of the above acids is usually used for acid leaching to remove impurity minerals.
Considering the dissolving effect of HF on quartz, the HF concentration generally does not exceed 10%. In addition to the acid concentration, the amount of acid, acid leaching time, temperature, slurry stirring, etc. can affect the effect of quartz acid leaching. The control of various factors in acid leaching should be based on the final grade requirements of quartz. The concentration, temperature and dosage of acid should be reduced as much as possible, and the acid leaching time should be reduced to achieve quartz purification with lower mineral processing costs.
Due to the strict requirements on the iron element in quartz, some countries have conducted systematic research on the acid leaching and purification of quartz and established acid leaching quartz beneficiation and purification plants. After acid leaching, high-purity quartz with a purity of 99.99% can be obtained.
06 Other purification methods
Due to the different requirements of different quartz products for the content of impurity minerals, other purification methods are sometimes used for further purification. This method can remove the gas and liquid impurities contained in the quartz and the surface contamination caused by impurity minerals and metal inclusions during the processing, so that the quartz sand can be further purified.
07 Summary
This article mainly discusses five quartz sand purification processes, including water washing; scrubbing; magnetic separation; flotation; acid leaching.
Due to the differences in properties such as ore particle size, in the actual mineral processing process, it is necessary to determine the specific mineral processing process according to the actual situation.
- Random article
- Popular articles
- Popular comments
- Iron Ore Roasting and Magnetic Separation Process
- Nickel ore priority flotation process(Sulfide ore)
- Zirconium Ore Processing: Gravity, Magnetic, and Flotation Methods
- Chromium Ore Gravity Separation and Flotation Process
- Basic techniques for antimony ore flotation processing
- Efficient purification of manganese ore by magnetic separation process
- Effective Flotation Processes for Copper-Molybdenum Ores
- 1Ta&Nb Ore Processing Plant: 200 Ton Per Day in Sierra Leone
- 2Tantalum-Niobium Ore Combined Beneficiation Guide
- 3Common Copper Oxide Processing Methods: 2 Types Explained
- 4Mini Gold Wash Plant
- 5Iron Ore Combined Beneficiation Process
- 6Henan Lingbao’s New 600-Ton Carbon Slurry Plant Underway
- 7Sulfide Ore Nickel Ore Mixed Flotation Process
Leave a message with your needs or comments
Add comment: