Mica is one of the common associated minerals of quartz sand. For quartz sand, mica is an impurity. The removal of mica is an important part of quartz sand purification.
一. What is mica?
Mica is the general name of the mica group minerals, which are aluminosilicates of potassium, aluminum, magnesium, iron, lithium and other metals. They are all layered and monoclinic. The crystal is in the form of pseudo-hexagonal sheet or plate, and occasionally columnar. The layered cleavage is very complete, with glass luster, and the thin sheet is elastic. There are biotite, phlogopite, muscovite, etc.
二. How to remove mica?
a. Crushing, screening and separation
This method has simple process flow, less equipment, high production efficiency and strong separation ability. The required sorting equipment is basically the same as the main processing equipment of the gravel processing system, and can be used in the gravel processing system. Mica separation can be realized by carrying out targeted de-mica transformation on the ordinary crushing and screening process.
b. Shaking table gravity separation
The process of shaking table gravity separation is simple and the separation capacity is good, but it requires additional equipment such as shaking table, high energy consumption, large water consumption and large site occupation. Before considering the shaking table equipment, the sand and stone processing system needs to carry out the shaking table separation test on the broken ore, and weigh the advantages and disadvantages according to the separation effect.
Some mica has weak magnetism, which can be removed by magnetic separation. Magnetic separation can remove ferriferous mica. Before considering the magnetic separation operation, the sand processing system needs to conduct chemical analysis on the properties of the raw ore and the mica minerals contained in the sand to determine whether there is iron, and conduct magnetic separation test according to the iron content.
d. Wind selection
The mica air separation method is based on the difference in the settlement speed of mica and gangue in the air flow. Generally, the process of “crushing and grading air separation” is adopted, in which special equipment is required for air separation. This method needs to be combined with screening and other methods to achieve mica separation effect.
At present, there are many types and models of air separators with mature technology, which can be directly used in sand and stone processing system. The principle of air separation is similar to that of the dust collector of the sand and gravel system, which requires the raw ore to be kept dry, so the air separation method is only suitable for the sand and gravel processing system produced by dry method. According to the data, when the moisture content of the raw ore exceeds 2%, the fine sand is easy to adhere to the surface of the mica, resulting in the blocking of the screen of each section of the vibrating screen and affecting the removal effect of the mica.
e. Flotation
The mica and quartz sand are sorted according to their different surface physical and chemical properties. The quartz ore is broken and ground to separate the mica monomer. Under the action of reagents, mica becomes a foam product and is separated from gangue. Mica flotation can be carried out in acidic or alkaline pulp. Cations of long-chain amine acetate and anions of fatty acids are used as collectors for mica.
The flotation method is mainly used for the recovery of broken mica and fine mica in the sand and gravel industry, especially the mica resources in tailings. In practical production application, the preliminary process flow should be determined according to the nature and characteristics of the actual ore, and then enriched and optimized through a series of conditional tests to obtain better technical and economic indicators.
The flotation method has strict requirements on the pH value of the pulp, and a large number of chemical reagents such as adjusting agents (pH adjusting agents and dispersants), collectors, inhibitors, etc. need to be added. The flotation method has large water consumption, high cost and great difficulty in wastewater treatment.
三. Summary
Due to the particularity of the sand and stone processing system, the physical separation method for removing mica is a reasonable choice. The mica separation method of crushing and vibration screening can be selected by using the existing crushing and screening equipment of the sand and stone system. This method has certain requirements for crushing and screening equipment. The sand and stone processing system with more mica should carry out a series of targeted crushing and screening tests before selecting equipment and determining processing technology.
Magnetic separation and shaking table gravity separation require more equipment and large site, and the production cost is high. The sand processing system needs to decide whether to use this method according to the properties of sand raw materials and the results of preliminary tests. The separation principle of air-separated mica is simple and the production cost is moderate. It is more practical for the sand and stone processing system produced by dry method. The mica separation can be carried out by selecting appropriate air-separated equipment and process.
Mica will have a certain impact on the quality of photovoltaic glass quartz sand products, such as iron and aluminum content. The removal amount of mica depends on the quality index requirements of the finished sand. If you have the need for quartz sand purification, Fodamon engineers will give a reasonable plan and equipment according to your situation.