Mica belongs to aluminosilicate minerals, which can be divided into three subtypes: muscovite, biotite and lepidolite. Among mica, muscovite and phlogopite (phlogopite belongs to biotite subclass) have industrial application value. There are three common mica processing processes, namely, mica beneficiation and purification, flaking and fine grinding. This article introduces the application fields of mica and three common processing methods.
Muscovite is characterized by hard texture, high mechanical strength, high temperature resistance and rapid temperature change; In addition, mica is widely used in industry due to its good cleavability (peeling and splitting along the dissociation surface), elasticity and flexibility. Phlogopite has high heat resistance and is a good heat-resistant insulating material.
Flake mica is generally used for electronic tube feeding sheet and punching parts in radio industry, parts specification sheet and capacitor chip used in aviation industry and capacitor production department, mica sheet used in motor manufacturing, and various specifications sheet used in daily electrical appliances, telephones, lighting, etc.
Fragmentary mica refers to the general term of fine mica extracted, waste residue after processing and stripping, and leftover materials after parts processing. It is mainly used to produce all kinds of mica paper and mica board as insulating materials and is widely used in the electrical industry; Production of various mica powder, used for engineering plastics and rubber, paint, linoleum and other roofing materials, cable cladding, welding electrodes, mica ceramics, pearlescent mica pigment, mica casting products, etc.
The mineral processing and purification methods of mica are classified according to the nature and types of mica. Generally speaking, the flaky mica is generally selected manually, friction beneficiation, shape beneficiation, etc., while the crushed mica is selected by air and flotation.
1. Manual picking
On the mining face or mine mouth ore pile, select the mica that has been separated by monomer; The intergrowth of mica and gangue is broken by hand hammer, and then the mica is selected.
2. Friction beneficiation
According to the difference between the sliding friction coefficient of flaky mica and the rolling friction coefficient of round gangue, mica and gangue are separated. One of the equipment used is the inclined plate separator.
This machine is composed of a group of metal inclined plates. During the sorting process, large gangue rocks roll down to the waste rock heap; Mica and small vein stones are blocked by weir plate and fall to the next inclined plate through the gap. Repeat the above process on the inclined plate in turn to gradually separate mica and gangue.
3. Shape beneficiation
According to the different shapes of mica crystals and gangue, the ability of passing through the gaps or holes of the sieve during screening can separate mica and gangue. During sorting, a screen with more than two layers of different screen surface structures is used. Generally, the screen mesh of the first layer is square. When the raw ore enters the screen surface, flaky mica and small gangue can leak from the slot of the strip screen to the screen surface of the second layer due to vibration or rolling. Since the second layer is a grid screen, the gangue can be screened to leave flaky mica.
1. Mica flotation
After ore crushing and grinding, mica and gangue monomer are separated. Under the action of flotation reagents, mica becomes a foam product and is separated from gangue.
At present, there are two flotation processes: one is to use amine collector to float mica in acidic medium, with pH value controlled below 3.5. Desliming is required before flotation, and the solid content of pulp is 30%~45%;
Secondly, in alkaline medium, anionic collector is used for flotation, and the pH value is controlled at 8-10.5. Desliming is also required before flotation. Mica flotation process requires multiple concentration.
2. Mica air separation
Mica air separation is mostly realized by special equipment. The process is generally as follows: crushing → screening and grading → air separation.
After the ore is broken, mica basically forms a thin slice, while gangue minerals feldspar and quartz are massive particles. According to this, the selected materials are divided into narrow particles by multi-level classification, and special air separation equipment is used for separation according to the difference of suspension speed in the air flow.
Stripping raw mica into mica flakes of various specifications is called mica flake. At present, there are three kinds of peeling methods: manual peeling, mechanical peeling and physical chemical peeling. They are mainly used to process various mica flakes, such as thick mica, thin mica, and electronic tube mica. Most of them are manual operations.
Fine grinding and superfine grinding of mica, that is, the production of mica powder, can be divided into dry method and wet method.
The dry fine grinding and superfine grinding equipment for mica mainly includes ball mill, rod mill, vibration mill, stirring mill, air flow mill, high-speed mechanical impact mill, etc.
In the production of ultra-fine mica powder, dry classification equipment (turbine air centrifugal classifier) is generally required; In the production of coarse mica powder, the plane shaking screen, suspension screen and vibrating screen are generally used for grading.
The main equipment for wet grinding mica powder includes wheel mill, sand mill, mixing mill, high-pressure homogenizer, etc. Wet ground mica powder has the advantages of pure texture, smooth surface, large diameter thickness ratio and strong adhesion.
Therefore, wet ground mica powder has better performance, wider application and higher economic value. Especially, the mica powder used as the base material of pearlescent mica generally requires wet grinding of mica powder. Wet grinding technology is the main development trend in the production of fine mica powder.
The above introduces the application fields and processing methods of mica. The beneficiation test can be carried out before determining the processing technology. The application direction of mica can be determined according to its own characteristics, which can play its role to a greater extent and create greater value for you. If you need mica processing, please contact Xinhai Mining!
