Industrial silicon furnace: how to repair the carbon brick furnace eye?

Industrial silicon furnace is a kind of submerged arc furnace, as the name suggests, it is mainly used to smelt industrial silicon solution. In the entire industrial silicon furnace, the life of the furnace eye part is the weakest, and it is extremely vulnerable to high temperature slag erosion and silicon solution erosion, so the damage is the fastest. This part is currently mainly carbon brick.

1. The damage mechanism of the furnace eye carbon brick

There are two main damages to carbon bricks used inindustrial silicon furnace bores, namely, the shortcomings of easy oxidation of carbon bricks and mechanical erosion caused by high-temperature solutions and molten slag.

1.1 Carbon brick oxidation

The bores of industrial silicon furnaces are generally made of carbon bricks. Although the application of carbon bricks in this part has a strong advantage, the product has a fatal point-easy to oxidize. The carbon bricks in the industrial silicon furnace eye are exposed to the air for a long time, so the oxidation rate is faster.

1.2 Mechanical erosion

When the silicon liquid is discharged from the industrial silicon furnace, the outflowing high-temperature silicon melt washes the carbon bricks of the furnace hole, which enlarges the furnace hole. 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 furnace eye carbon brick to be strongly mechanically washed. Moreover, the industrial silicon furnaceis operated intermittently, and the temperature difference between the silicon output and the plugging hole increases, which easily causes the carbon bricks to peel off under the condition of rapid cooling and rapid heating. In addition, the unreasonable current distribution in the submerged arc furnace is one of the important reasons for the damage of the furnace hole carbon bricks.

2. Furnace eye repair method

The furnace eye is corroded and mechanically washed by high-temperature furnace gas, molten silicon water and high-temperature slag, forming an oval furnace eye. After the furnace eye is large, it is difficult to plug the eye, and often run out and fire, so you need to replace the furnace eye. .

2.1 Traditional furnace eye repair method

In traditional industrial silicon furnace, technicians repair the damaged furnace eye. Clean up the silicon and slag deposits from the silicon outlet, pour 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, the 5 furnace holes are used in rotation. The furnace eye must be repaired after 5-7 days of use, which will seriously affect the improvement of various technical and economic indicators of the product. Frequent repairs lead to the shortcomings of high labor intensity, poor working environment, long time-consuming, high maintenance cost, and low efficiency.

2.2 New furnace eye repair technology

The traditional furnace eye repair is contrary to the policy of reducing costs and increasing efficiency, so a new furnace eye repair technology is urgently needed to solve the problem of low efficiency of furnace eye repair. Figure 1 is a comparison between the new repair technology and the traditional repair process. The specific repair technology is as follows:

① Use a professional drilling rig to gouge the damaged charcoal brick furnace bore. The depth and diameter of the gouging bore depends on the degree of damage to the furnace bore.

②For the chiseled furnace hole, use the composite filler of electrode paste, silicon carbide, pitch and other materials to fill the furnace hole. The reason for choosing the composite filler is that the filler has very good fluidity, forming and bonding capabilities after heating, and can be fully sintered with the original furnace hole carbon brick as a whole. Moreover, the silicon carbide material has certain anti-oxidation and wear resistance properties. It can effectively slow down the damage caused by oxidation and erosion, and extend the life cycle.

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.

④Usingelectrode paste and fine gap paste to fill the gap between the filler and the graphite carbon sleeve, so that the furnace hole carbon brick and the carbon sleeve are coked together.

⑤Use high-aluminum castable to repair the chute, after repairing, pour the protective layer with electrode paste.

After the above repair is completed, it needs to be baked before it can be used in production. This technology has been widely promoted in the same industry in China. It can be seen from the use situation that this technology can effectively extend the life of the furnace eye, reduce the number of furnace eye replacements, reduce the cost of furnace eye repair, and improve industrial silicon furnaces. The output and economic benefits.