How is metallic silicon made? The whole process of metallic silicon smelting.
The smelting process of metallic silicon mainly includes raw material preparation, feeding, smelting, furnace discharge and cooling. The following are the detailed steps:
1. Raw material preparation
Raw material selection: The main raw material of metallic silicon is high-purity quartz or silica, and carbonaceous reducing agents such as coke, petroleum coke, etc. need to be added at the same time.
Raw material crushing and screening: Quartz and reducing agents need to be crushed and screened to a suitable particle size for uniform feeding and sufficient reaction.
Batching: The ingredients are proportioned to make the ratio of silicon and carbon accurate to ensure stable reaction.
2. Feeding
Use a feeding car or hopper to deliver the raw materials to the top of the smelting furnace, and gradually add them into the furnace according to the set feeding frequency and amount to ensure the continuity of the smelting process.
3. Smelting
High temperature reaction: Smelting is carried out in an electric arc furnace or a submerged arc furnace. The temperature in the furnace is usually between 1600℃ and 2000℃.
Chemical reaction: At high temperature, the carbonaceous reducing agent reacts chemically with silica to produce metallic silicon and carbon monoxide gas:
SiO2+2C→Si+2CO
Gas treatment: The generated carbon monoxide gas will be discharged, and an exhaust gas treatment system is usually equipped to reduce pollution.
4. Ramming operation
During the smelting process, a ramming car or ramming equipment is used to compact or ram the charge to ensure the charge density, prevent voids, and promote the uniformity of the reduction reaction.
5. Discharging
After smelting, the molten metallic silicon is pushed to the discharge port by a pusher, or other discharge methods are used to discharge the metallic silicon.
Slag separation: When discharging, impurity slag will be generated. Usually, physical methods are used to separate metallic silicon and slag to obtain pure metallic silicon liquid.
6. Cooling and casting
Cooling: The metallic silicon liquid after discharging is cooled naturally in a specific cooling tank or quickly cooled by air cooling or water cooling.
Ingot molding: After cooling, the metallic silicon will form blocks or ingots, which is convenient for subsequent transportation and sales.
7. Finished product testing
Quality testing is performed to ensure that the purity, impurity content and physical properties of metallic silicon meet the standards.
8. Waste gas and slag treatment
The waste gas and slag generated during the smelting process need to be treated to meet environmental protection requirements. The waste gas is usually treated by filter bags or washing towers, and the slag is recycled or discarded.
Key equipment
Smelting furnace (arc furnace, submerged arc furnace)
Furnace charging vehicle
Furnace ramming vehicle
Materail pushing vehicle for furnace
Cooling system
Waste gas treatment system
Through the above process, the silicon dioxide in the raw material can be efficiently reduced to metallic silicon. The finished product is mainly used in alloy manufacturing, electronics industry and chemical industry.
