Industrial silicon furnace is a kind of ore-heat furnace. As the name implies, it is mainly used to smelt industrial silicon solution. In the whole industrial silicon furnace, the service life of the furnace eye is the weakest. It is very easy to be corroded by high-temperature slag and washed by silicon solution, so it is damaged the fastest. This part is currently mainly made of carbon bricks.

Mechanism of Damage to Furnace Eye Carbon Bricks

There are two main types of damage to carbon bricks used in furnace eye of industrial silicon furnace, namely, the easy oxidation disadvantage of carbon bricks themselves and mechanical erosion caused by high-temperature solution and slag.

1.1 Carbon brick oxidation

The furnace eye of an industrial silicon furnace is generally built with carbon bricks. Although carbon bricks have strong advantages in this area, this product has a fatal point – easy oxidation. The carbon bricks in the furnace eye of industrial silicon are exposed to the air for a long time, so the oxidation rate is relatively fast.

1.2 Mechanical erosion and erosion

When the industrial silicon furnace discharges silicon liquid, the high-temperature silicon melt flows out and scours the carbon bricks in the furnace eye, causing the furnace eye to expand. When the slag viscosity is high, the fluidity is poor, the slag discharge is not smooth or the furnace eye is difficult to open, the manual eye opening operation will cause the carbon bricks in the furnace eye to be subjected to strong mechanical erosion. Moreover, the industrial silicon furnace is an intermittent furnace discharge operation, and the temperature difference between the silicon discharge and the eye plugging is increased, which easily causes the carbon bricks to peel off under the condition of rapid cooling and heating. In addition, unreasonable current distribution in the ore-heating furnace is one of the important reasons for the damage of carbon bricks in the furnace eye.

Furnace Eye Repair Methods

The furnace eye is eroded and mechanically washed by high-temperature furnace gas, molten silicon water and high-temperature slag, forming an elliptical furnace eye. It is difficult to plug the eye after the furnace eye is empty, and the eye often runs and sprays fire. At this time, the furnace eye needs to be replaced.

2.1 Traditional furnace eye repair method

The traditional industrial silicon furnace furnace eye is repaired by technicians after the damage. Clean the silicon and slag accumulation at the silicon outlet, fill the damaged furnace eye inside and outside with electrode paste, and tie the protective layer with castables. During the production of the submerged arc furnace, 5 furnace eyes are repaired and used in rotation. The furnace eye needs to be repaired again after about 5 to 7 days of use, which seriously affects the improvement of various technical and economic indicators of the product. Frequent repairs lead to the disadvantages of high labor intensity, poor working environment, long time consumption, high maintenance cost, and low efficiency.

2.2 New furnace eye repair technology

Traditional furnace eye repair is contrary to the principle of reducing costs and increasing efficiency, so it is urgent to adopt a new furnace eye repair technology to solve the problem of low furnace eye repair efficiency.

Compared with the traditional repair process, the new repair technology is as follows:

①Use a professional drill to drill the damaged carbon brick furnace eye. The depth and diameter of the drilled hole depend on the degree of damage to the furnace eye.

②For the drilled furnace eye, use a composite filler with electrode paste, silicon carbide, asphalt and other materials to fill the furnace eye. The reason for choosing this composite filler is that the filling material has excellent fluidity, molding and bonding ability after heating, and can be fully sintered with the original furnace eye carbon brick into a whole. Moreover, silicon carbide material has certain anti-oxidation and wear-resistant properties. It can effectively slow down the damage caused by oxidation and erosion and extend the service life.

③The filled furnace eye needs to be inlaid with a graphite carbon sleeve. The graphite carbon sleeve has good wear-resistant mechanical properties and is resistant to oxidation and corrosion, which can effectively protect the furnace eye carbon brick.

④ Use electrode paste and fine seam paste to fill the gap between the filler and the graphite carbon sleeve, so that the furnace eye carbon brick and the carbon sleeve are coked into one.

⑤ Use high-aluminum castables to repair the chute. After repair, use electrode paste to pour the protective layer.

After the above repairs are completed, it needs to be baked before it can be used in production. This technology has been widely promoted among domestic peers. From the use situation, it can be seen that this technology can effectively extend the service life of the furnace eye and reduce the number of furnace eye replacements. Reduce the cost of furnace eye repair and increase the output and economic benefits of industrial silicon furnaces.