Purification is an important means to improve the grade and quality of mica and realize high-grade application, but in the actual production process, it is difficult to synthesize mica powder and mica purification, mainly in the following aspects:

The specific gravity and dielectric constant of mica crystals and intergrown minerals are almost the same, and the conventional beneficiation methods are not effective;

The flake structure of mica needs to be protected during the beneficiation process;

Each mica crystal in the ore has different shapes, different areas and different thicknesses;

Mica ores from different deposits are very different from each other in their technological characteristics.

At present, the purification methods of mica at home and abroad include hand selection, friction purification, shape purification, wind separation, gravity separation and flotation, etc. Among them, flake mica usually adopts hand selection, friction purification and shape purification. Mica is selected by wind, gravity or flotation.

1. Purification by hand selection of mica

The manual selection method is to manually select the mica that has been separated from the monomer on the ore working face or the ore pile at the pit, or to break the conjoined body with a hammer to select the mica.

The method does not require complex equipment, but is labor-intensive, and the recovery rate of beneficiation can reach 80%, which is suitable for small mine production.

2. Purification by mica friction beneficiation method

The friction beneficiation method is based on the difference between the sliding friction coefficient of the mica crystal and the rolling friction coefficient of the circular gangue block. There are many equipments used, such as metal plate separators, spiral separators, and oblique separators with deflectors. Plate sorters and inclined plate sorters with "hill-shaped" plates, etc.

When the method is used to produce mica ore, the production efficiency is relatively high, but it also has great shortcomings. The main reason is that when the thickness of the ore exceeds the thickness of the ore, the mica crystals with a shape similar to the gangue block are easy to enter the gangue, and the flaky gangue may also enter the gangue. In the mica concentrate, and the current friction beneficiation process and mechanical equipment are not perfect, therefore, in the industrial production of mica beneficiation, friction beneficiation has not been widely used.

3. Purification by beneficiation method of mica shape

The shape beneficiation method realizes separation according to the different shapes of mica crystals and gangue, and the mechanical equipment used are cylindrical sieves and vibrating sieves. This method generally uses more than two layers of sieves with different sieve holes. After the raw ore enters the sieve surface, due to vibration or rolling, small pieces of flake mica and gangue can leak from the first layer of sieve to the second layer of sieve surface. The stone falls under the sieve, while the flake mica remains on the sieve surface, enabling sorting.

The method has simple process, less equipment, high production efficiency and strong sorting ability, and is widely used in mica mining enterprises.

4. Purification by wind separation of mica

The wind sorting method is based on the difference in the sedimentation speed of mica and gangue in the airflow. After the ore is crushed, the mica basically forms flakes, while the gangue minerals feldspar and quartz are in the form of massive particles. Accordingly, multi-level classification is used to pre-select the selected materials into narrower particle sizes. According to the difference of their suspension speed in the airflow, special air separation equipment is used for classification. The process generally adopts "crushing-classification-wind separation". process flow.

This method is not efficient, and requires multi-stage sorting or cooperation with other methods to obtain the final product. According to the difference of the sedimentation speed of the ore particles in the air flow, the air separation method can be subdivided into the chamber separation method, the vibration air separation method, the air separation method and the zigzag air separation method. Generally speaking, it is more common to use air classifiers for air separation in mica beneficiation.

5. Purification by mica re-selection method

Gravity separation is a beneficiation method based on the difference in density or particle size between mica and gangue minerals. The commonly used gravity separation equipment includes shaking table and spiral chute.

6. Purification by mica flotation method

The separation of mica and gangue minerals by flotation, like the flotation separation of other minerals, is also based on the difference in the crystal structure and material composition of useful minerals and gangue minerals, and is achieved by adjusting the chemical conditions.

The flotation method is mostly used to recover the finely divided mica with a smaller mica crystal contour area. The United States has successfully developed two flotation methods - one is to use cationic collectors to flotate mica in acidic media, and the other is to use anionic and cationic collectors to flotate mica in alkaline media. In addition, these two methods can also be used in combination.

In actual production and application, it is necessary to determine the preliminary purification process according to the properties and characteristics of the actual mica ore, and enrich and optimize the process through a series of condition tests to obtain the most optimized technical and economic indicators.