Mica processing technology

Industrial indicators

Mica mining for the electrical industry must be a mica block with an effective area of more than 4 cm2 and no cracks or perforations. The non-mica minerals on the edges must not exceed 3 mm. After mica mining, the quality is divided into four categories according to the effective area, and the best special type area is larger than 65 square centimeters.

Process flow

The beneficiation of mica ore is the enrichment process of raw mica. Raw mica refers to mica crystal of any thickness in the original ore with a contour area greater than or equal to 4 cm2. The amount of raw mica in raw ore is called the raw mica mineralization rate, which is usually expressed by the weight of raw mica contained in the unit ore volume (kg/m3). The ratio of the total weight of raw mica in the concentrate obtained from the ore dressing to the total weight of the raw mica contained in the ore is called the recovery rate.

The industry mainly uses mica natural crystals directly to process the desired products. The larger the mica crystal without defects, the higher its economic value. Therefore, in the process of beneficiation of mica ore, it is necessary to protect the natural crystals of mica from damage as much as possible.

For the beneficiation of mica with a crystal contour area larger than 4 cm, it is mainly based on the difference in shape and friction coefficient between mica crystal and gangue. The commonly used methods are hand selection, friction selection and shape selection. For the crushed mica with a crystal contour area of less than 4 cm, it is mainly sorted according to the difference between its physical and chemical properties on the surface of the gangue. The method used is flotation.

Mica seed dressing method and process

a, hand selection

Workers select the mica that has been separated by monomer on the mining face or the pit ore heap; the mica and the gangue are broken by hand hammer, and then the mica is selected.

b, friction dressing

The mica crystal and the gangue are separated according to the difference between the sliding friction coefficient of the slab-shaped mica crystal and the rolling friction coefficient of the spheroidal gangue. One of the devices used is a swash plate sorter. The machine is composed of a group of metals consisting of the swash plate, the swash plate of each length of 1350mm, width of 1000mm, under an angle larger than the inclination of the swash plate on a swash plate. A slit for collecting mica crystals is left at the lower end of each swash plate, and the width thereof is sequentially decreased in the order of slanting plates. The front edge of the slit is equipped with a triangular raft. During the sorting process, the large gangue rolls down to the stone pile; the mica and the smaller gangue block are blocked by the raft, and the sloping plate is dropped through the gap. The above process is repeated on the swash plate in turn to gradually separate the mica from the gangue. The friction beneficiation process and equipment are not perfect, so this method has not been widely used in mica ore dressing.

c, shape dressing

According to the shape of the mica crystal and the gangue, the ability to pass through the sieve slit and the sieve hole in the sieve is different, and the mica and the gangue are separated. When sorting, a sieve having two or more different sieve surface structures is used, generally the first sieve mesh is strip-shaped; the second sieve mesh is square. When the ore enters the sieve surface, due to vibration or rolling action, the flaky mica and small gangue can leak from the strip sieve to the second sieve; because the second layer is sieve, the gangue can be sieved. Lower flaky mica. The shape beneficiation method has the advantages of simple process, less equipment, high productivity, good sorting effect, etc., and thus has been widely used in mica mines.

Mica broken process

a, flotation

Sorting according to the difference in surface physicochemical properties of mica and gangue. The ore is broken and ground to dissociate the mica monomer. Under the action of the agent, the mica becomes a foam product and is separated from the gangue. Mica flotation can be carried out in an acidic or alkaline slurry, and the long carbon chain amide cations and fatty acid anions are mica collectors . In the mica flotation process, three rough selections and three selections are required to obtain the mica concentrate. Therefore, mica ore float is used to recover mica and fine-grain mica below 14 mesh in pegmatite and mica schist. In China, mica ore flotation has not yet been produced and applied.

b, wind selection

Mica wind selection is mostly achieved through special equipment. The process is generally: crushing→sieving classification→wind selection. After the ore is crushed, the mica is basically formed into a flaky shape, and the gangue mineral feldspar , quartz and the like are in the form of massive particles. Accordingly, the multi-level grading is used to pre-divide the selected materials into narrower granules, and according to the difference in the levitation speed in the airflow, special air-conditioning equipment is used for sorting. The wind selection method is applicable to areas where water is scarce and has been used for actual production.

Production example

After the raw ore is manually sorted out of large mica, it is fed into the concentrating plant to fix the rod sieve, and the size of the sieve is 100mm. After the +100mm material is broken into the jaw crusher , it will enter the XB-602 vibrating screen sorting together with the product under the bar screen. The sieve has two layers of sieves, the upper layer is a bar sieve made of angle steel, the sieve width is 20 mm; the lower layer is a 20×20 mm square hole sieve, and after sorting, three kinds of products are obtained: materials larger than 20 mm sieve size, Mica and Liansheng body were selected from the hand, and the mica of more than 4cm2 was manually picked up by artificial crushing; the materials of less than 20mm sieve joint and larger than 20mm square mesh were also selected from the middle of the hand, and the artificial body was broken. After that, mica larger than 4cm2 is sorted; materials smaller than 20mm square mesh are all discarded as tailings.

The beneficiation process consists of two parts: re-election and flotation. Re-election uses a spiral concentrator. The purpose is to remove coarse tailings. The selected coarse concentrate is re-elected into the flotation. Three mixing tanks are used before flotation. The first mixing tank is added with lignosulfonate (or sodium silicate) to disperse the slime, and then the sodium carbonate is added to adjust the pH of the slurry to about 10; the second blending tank is added with the fatty amine acetate cation collector to make It interacts with the side of the muscovite and adsorbs it; the fat in the third blending tank is added with the amine acetate salt cation collector, so that it absorbs with the muscovite layer, and then the foaming agent is added. After a rough selection three times, the mica concentrate is obtained. The mica concentrate has a grade of 98% and a recovery rate of 85%. Mica is mainly crystallized into a monoclinic system, and the crystals are pseudo-hexagonal flakes, scales, plates, and sometimes pseudo-hexagonal columns. Hardness 2~3, specific gravity 2.70~3.20.

Mica powder has unique acid and alkali resistance chemical stability, heat resistance and non-combustibility, and good insulation. It is increasingly used in international and domestic markets. Can be used in the building materials industry instead of asbestos products. The industry mainly uses its insulation and heat resistance, as well as acid, alkali, pressure and strip resistance, as insulation materials for electrical equipment and electrical equipment; secondly, it is used to manufacture steam boilers and smelting furnaces. Windows and mechanical parts. Mica crushed and mica powder can be processed into mica paper, or it can replace various mica sheets to produce various low-cost, uniform thickness insulation materials.