Energy Saving Ferrosilicon and Submerged Arc Furnace

Energy Saving Ferrosilicon and Submerged Arc Furnace

Ⅰ.  Equipment Structural Characteristics

1. Composite Electrode Structure

The composite electrode structure of energy-saving industrial ferrosilicon submerged arc furnace fully utilizes the skin effect characteristics of high current conductors in its design. Three small graphite electrodes are sintered together with electrode paste and continuously pressed off during the production process as needed. It not only has a huge energy-saving effect, but also has a low electrode cost advantage.

2. Composite Gripper Structure

By fully absorbing the advantages and disadvantages of the combined gripper and copper tile gripper, and combining the two structures together, not only does it solve the problem of poor contact of the copper tile structure leading to high current input, but it also ensures automatic electrode detachment and product quality.

3. Arched Hood (also known as bowl shaped hood)

The arched smoke hood designed fully utilizes the flow principle of hot flue gas and has an octagonal structure made entirely of stainless steel. The electrode can be lifted as a whole above the hood for maintenance, reducing maintenance intensity and shortening maintenance time. Moreover, the smoke collection effect (environmental protection effect) is very good, and it is of great significance for improving the quality of silicon powder, an auxiliary product of industrial silicon.

4. Smelting Transformer and Furnace Bus Bar. Special internal design structure is provided to change the high voltage distribution process used in traditional industrial silicon production, and as many as 24-36 groups of secondary outlet terminals and specially designed furnace bus bar structure are used, which has a very significant energy-saving effect.

5. Material Cutting System

The lower part of the material pipe adopts a spring type rotary tube structure, and the gate valve adopts a large inclination angle (controlled by a three position solenoid valve). The material bin is treated in layers.

6. The Furnace Shell is Treated with Magnetic Isolation.

7. Furnace Construction Process Plan

Adopting a masonry design scheme that breaks away from conventional thinking patterns, only 400-600mm high circular carbon bricks are used for lining construction, and special treatment is applied to the high alumina bricks on top of the circular carbon bricks. This not only ensures the safety of the lining, but also has significant practical significance for deep insertion of electrodes and prevention of furnace bottom rise.

8. Other proprietary technologies: such as reasonable geometric and electrical configuration dimensions, guiding mechanisms for electrode columns, special-shaped brick sealing between electrodes and smoke hoods, loading and unloading systems, maintenance platforms, equipment water cooling, and circular low-carbon brick furnace construction are of great significance for improving the technical equipment level of industrial silicon production at home and abroad, and play a huge demonstration role in equipment operation rate and energy conservation and emission reduction for the development of the industry.

Ⅱ. Production Situation and Cost Advantages

1.Production Situation

At present, there are only two 39MVA industrial ferrosilicon furnaces from Henan Luoyang Shengyang Silicon Industry Technology Co., Ltd. and two 25.5MVA industrial silicon furnaces from Henan Dengdian Group (one in production and one under construction) using composite electrodes for industrial silicon production in China. However, both enterprises are located in the Central Plains region with high electricity prices and do not have a competitive advantage compared to low electricity price areas in the northwest and southwest. The former adopts a composite electrode structure with a single graphite electrode and a copper tile gripper, while the latter adopts a composite electrode with three graphite electrodes and a combined gripper (one under construction uses a composite gripper). The industrial silicon furnace in Luoyang only has the advantage of electrode cost and does not have the advantage of energy saving. Dengdian Group's not only has the advantage of electrode cost, but also has a greater advantage in energy saving.

2.  Cost Advantage

Composite electrodes are made by combining specialized electrode paste and graphite (or carbon) electrodes, sintering and forming them in an electrode shell to supply power to the furnace and achieve the production of high-grade industrial silicon through shell shedding. This type of electrode is regularly peeled according to production consumption and process requirements, with no or minimal consumption of the electrode shell. Its advantages are:

(1) Energy saving: The electricity consumption per ton of silicon smelting in large-scale industrial silicon furnaces using carbon electrodes in China is generally between 13000 and 14000 degrees, while the use of composite electrodes can reach below 12000 degrees.

(2) Electrode cost: The cost of one ton of silicon electrode for large industrial silicon furnaces with carbon electrodes (diameter over 1000mm) in China is between 1800-2200 yuan, while the cost of using composite electrodes is less than 1000 yuan.

(3) Production raw materials: The composite electrode fully utilizes the skin effect of high current conductors to directly deliver the load to the furnace bottom. There is almost no sparking during the production process, and the raw material consumption per ton of silicon is very low.

(4) Equipment operation rate: After the composite electrode is started, there will be almost no electrode accidents again. Even if an electrode accident occurs, production can be directly started without electrode baking, and the equipment operation rate is extremely high.