Production Process of Silicon Refining in Submerged Arc Furnace

Production Process of Silicon Refining in Submerged Arc Furnace

The production process of silicon smelting in a submerged arc furnace is briefly described as follows: silica, reducing agent, and loosening agent are mixed and sent to the industrial silicon submerged arc furnace, heated to a high temperature to cause a reduction reaction to generate industrial silicon liquid, refined to remove impurities, cast into silicon ingots, cooled and crushed, then classified and packaged, and the generated flue gas is processed to ensure environmental compliance.

The production process of silicon smelting in an electric furnace mainly includes the following steps:

I. Raw Material Preparation

Silica: As a key raw material for industrial silicon production, the quality of silica (i.e. quartz sand) has an important impact on the quality of finished industrial silicon. Silica ore resources are abundant, but high-quality vein quartz accounts for only a small part. About 7 to 3 tons of silica are required to produce 1 ton of industrial silicon.

Reducing agent: Commonly used reducing agents include charcoal, petroleum coke, coal, etc. These carbonaceous materials react chemically with silica in the furnace to reduce metallic silicon from silica.

Loosening agent: Such as wood chips, wood blocks, corn cobs, pine nut balls, coconut shells, etc., used to improve the air permeability of the charge.

2. Batching and Feeding

Batching: According to production requirements, raw materials such as silica, reducing agent and loosening agent are weighed according to a specific ratio.

Feeding: The weighed charge is delivered to the top silo of the submerged arc furnace workshop through the conveying facilities, and then the furnace operator adds the charge into the furnace.

3. Electrothermal Chemical Reaction

Heating: After power is turned on, the electrodes in the industrial silicon submerged arc furnace release electric sparks to heat the charge to more than 2000 degrees Celsius.

Reduction reaction: At high temperature, silicon dioxide reacts with carbonaceous reducing agent to produce industrial silicon liquid and carbon monoxide (CO) gas. CO gas then escapes naturally through the material layer.

4. Refining and Casting

Refining: A mixed gas of oxygen and air is introduced into the bottom of the silicon water bag to remove impurities such as calcium and aluminum, and further purify the composition of the industrial silicon melt.

Casting: The refined silicon melt is injected into the ingot mold and cooled to form a silicon ingot.

5. Subsequent Treatment

Crushing and grading: After the silicon ingot is cooled and demolded, it is crushed and graded.

Testing and packaging: The silicon blocks are sampled and tested to ensure that the product quality meets the standards before packaging and storage.

6. Flue Gas Treatment

The flue gas generated during the smelting process of the industrial silicon submerged arc furnace contains harmful substances and needs to be treated by environmental protection facilities. The flue gas enters the flue through the furnace hood, and is treated by air coolers, fans, bag dust collectors and other equipment. It can only be discharged after meeting the national emission standards.

7. Operation Process and Equipment Maintenance

Operation process: The furnace operator needs to perform ventilation, furnace tamping, material sinking, material addition and material pushing operations in a timely manner to ensure that the permeability, molten pool resistance and furnace temperature of the charge in the electric furnace are in the best state.

Equipment maintenance: The industrial silicon submerged arc furnace and its supporting equipment need to be inspected and maintained regularly to ensure the stability and safety of the production process.

In general, the production process of silicon smelting in a submerged arc furnace is a complex and delicate process that requires strict control of conditions and operating parameters in each link to ensure product quality and production efficiency.