What is the detailed introduction of silicon carbide production process? What is the silicon carbide

1. Main production process.

The silicon carbide production process is briefly described as follows:

Raw material crushing. The hammer crusher is used to crush the petroleum coke and crush it to the particle size required by the process.

Ingredients and mixing.

Ingredients and mixing are the processes of weighing and mixing according to the prescribed formula. The batching of this project adopts a platform, and the mixing adopts a concrete mixer, and the batching and mixing operations of petroleum coke and quartz sand are carried out in accordance with the process requirements.

Electric stove preparation. Electric furnace preparation is to re-trim and organize the furnace that was used last time so that it can be put into use again. The work includes cleaning the furnace bottom material, trimming the electrodes, cleaning and repairing the furnace wall, removing the loading force, 1 gear, checking and eliminating other defects of the furnace.

Including black silicon carbide and green silicon carbide, among them: black silicon carbide is made of quartz sand, petroleum coke and high-quality silica as the main raw materials, and is smelted at high temperature through a resistance furnace. Its hardness is between corundum and diamond, its mechanical strength is higher than that of corundum, and it is brittle and sharp.

Green silicon carbide is made of petroleum coke and high-quality silica as the main raw materials, adding salt as additives, and smelting at high temperature through a resistance furnace. Its hardness is between corundum and diamond, and its mechanical strength is higher than that of corundum. There are two different crystals of commonly used silicon carbide abrasives, one is green silicon carbide, which contains more than 97% SiC, which is mainly used for grinding cemented carbide tools.

The other is black silicon carbide, which has a metallic luster, contains more than 95% SiC, and has greater strength than green silicon carbide, but has lower hardness, and is mainly used for grinding cast iron and non-metallic materials.

This one is very hard, and with a brazed diamond tool, ultrasonic high-frequency vibration can be added to the tool.

Silicon carbide is also known as steel grit or refractory sand. The molecular formula is sic, its hardness is between corundum and diamond, the mechanical strength is higher than corundum, and it can be used as an abrasive and some other industrial materials. Silicon carbide for industrial use was successfully developed in 1891 and is the earliest artificial abrasive.

Although a small amount of silicon carbide is present in meteorites and the earth's crust, no mineral source has been found for mining so far.

First of all, the silicon carbide is sent to the hammer crusher for rough crushing, the qualified silicon carbide is sent to the cone crusher for fine crushing, and the unqualified ones are re-crushed, and the particles and powders of silicon carbide are divided into particle segments of different sizes by using a circular vibrating screen, and the silicon carbide materials required by screening can enter the next processing procedure, and the silicon carbide that has been broken through two sections enters the Raymond mill for grinding processing, and then the processing of the ultra-fine mill is carried out, and the ground silicon carbide powder is taken away by the air flow of the fan, and is graded by the analyzer. The silicon carbide powder that meets the requirements enters the cyclone collector for separation and collection, and so on to complete the production requirements.

Performance characteristics of black silicon carbide.

The high-grade refractory material made of black silicon carbide is resistant to thermal shock, small in size, light in weight and high in strength, and has good energy-saving effect. Low-grade silicon carbide (containing about 85% SiC) is an excellent deoxidizer that can be used to speed up steelmaking, facilitate chemical composition control, and improve steel quality. In addition, silicon carbide is also widely used to make silicon carbon rods for electric heating elements.

Black silicon carbide production process:

1. High-temperature smelting: Quartz sand, petroleum coke, silica and other raw materials are mixed according to the proportion and then added to the resistance furnace for high-temperature smelting. The finished product after smelting is a silicon carbide block.

2. Crushing: Silicon carbide has a high hardness, between white corundum and diamond, and the block is relatively large, it is difficult for ordinary crushers to crush it, we need to use jaw crushers for coarse crushing first.

3. Fine crushing: After the silicon carbide is coarsely crushed, it is necessary to use a cone crusher for fine crushing, which can crush the silicon carbide into a variety of specifications.

4. Sieving: The finely crushed silicon carbide is screened with particle size, and screened into silicon carbide sand with different particle sizes.

5. Grinding: When processing silicon carbide powder, one more grinding process is required, and the silicon carbide sand is put into the grinding machine for grinding processing, and the silicon carbide powder after grinding is screened again, and the screening can be reduced to different particle sizes.

1. The common method is to mix quartz sand with coke, use the silica and petroleum coke in it, add salt and wood chips, put it in an electric furnace, heat it to a high temperature of about 2000 °C, and obtain silicon carbide powder after various chemical processes. 2 6 Silicon carbide is an important abrasive because of its great hardness, but its application range exceeds that of ordinary abrasives. To prepare silicon carbide products, we must first prepare silicon carbide smelting blocks.

In industrial production, silicon carbide smelting blocks are usually made of quartz, petroleum coke, etc. as raw materials, auxiliary materials, and waste materials, which are prepared at high temperature by grinding and other processes to become a charge with reasonable ratio and suitable particle size. 3 6 The thermal equipment for preparing silicon carbide smelting blocks at high temperature is a special silicon carbide electric furnace, and its structure is composed of the bottom of the furnace, the end wall inlaid with electrodes on the inner surface, the detachable side wall, and the furnace core body. The firing method used in this electric furnace is commonly known as:

Buried powder firing. As soon as it is energized, the heating begins, the temperature of the furnace body is about 2500, or even higher, and the furnace reaches 1450 when the silicon carbide is synthesized, and CO is released. However, at 2600, silicon carbide will decompose, but the decomposed Si will form silicon carbide with C in the charge.

4 6 Each group of electric furnaces is equipped with a set of transformers, but only a single electric furnace is supplied with power during production, so as to adjust the voltage according to the characteristics of the electric load to basically maintain constant power, the high-power electric furnace should be heated for about 24h, and the reaction to generate silicon carbide after a power failure is basically over, and then after a period of cooling, the side wall can be removed, and then the charge material is gradually taken out. 5 6 The charge after high-temperature calcination from the outside to the inside are: unreacted material, binder layer, amorphous layer, second-grade silicon carbide layer, first-grade silicon carbide layer, and furnace core graphite.

In the above-mentioned layers, the unreacted material and a part of the oxide silicon carbide layer are usually collected as the waste material, and the other part of the oxygen silicon carbide layer is collected together with the amorphous matter, the secondary product, and some binders as the return material, and some of the binders with very tight bonding, large blockiness and many impurities are discarded. 6 6 The first-class product is graded, coarsely crushed, finely crushed, chemically treated, dried and screened, and magnetically separated to become black or green silicon carbide particles of various resistant particle sizes. To make silicon carbide powder, it also needs to go through a water separation process; To make silicon carbide products, it also needs to go through the process of molding and sintering.

The production process of silicon carbide powder is characterized in that the steps are as follows:

1) Take silicon carbide raw materials, crush them in a crusher, and screen them to silicon carbide particles no larger than 5mm, and then shape them to silicon carbide particles no larger than 2mm with a shaping machine, and the oval particles account for more than 80, and then pickle and remove impurities and dry;

2) the above-mentioned dried silicon carbide particles are crushed into the silicon carbide powder of D50 with a pulverizer, and when crushing, the current of the main engine of the mill is set to 65-75A, the flow rate of the fan is set to 40-50m3 min, and the speed of the analyzer is 400--600 rpm;

3) then use vortex air flow classifier to classify silicon carbide powder, during classification, the fan flow rate of vortex type airflow classifier is 25-43m3 min, the speed of classifying wheel is 2600--3300 rpm, the finished product A of particle size DS94 is separated from the grading port, and the semi-finished product of DS94 is separated from the cyclone port;

4) the semi-finished product separated by the vortex type air flow classifier cyclone outlet is then secondary graded with the impeller type air flow classifier, during the classification, the fan flow rate of the impeller type air flow classifier is 25-10m3 min, the speed of the classifier wheel is 1300--1700 rpm, the finished product B with particle size of DS94 is separated from the classification port, and the by-product is separated from the cyclone port.

Sieving Sieving is to divide particles and powders into particle segments of different sizes. A single TS vibrating screen can be equipped with 4 layers of screens, which can continuously sort 2-5 particle sizes and control a narrow particle size range.

Sift out impurities. The high-performance sieve can quickly remove large or small particles with a low percentage of slurry residue separation in the process of high flow processing. TS vibrating sieve can quickly remove the insoluble solid matter in all kinds of slurry, and continuously discharge the slag.

Quartz sand + carbon (petroleum coke or charcoal or coal, the less ash, the better), energized (graphite powder core) heated to 2000 degrees.

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