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Problems in self-baking carbon bricks during the roasting process of submerged arc furnace
Dec 19, 2018

Self-baked carbon brick is the most ideal refractory lining for the bottom of the submerged arc furnace. However, if it is used improperly or the product is unqualified, there may be a series of problems, such as the following:


1. The furnace body design is unreasonable or the furnace furnace process is unreasonable, which leads to the collapse of the hearth ring brick in the oven.


The side carbon brick of the hearth should not be designed too high. It is prone to softening and collapse accident when it exceeds 600mm. If the seam is too large when the furnace is built, the volatilization of the seam is too large and it is easy to cause the collapse of the ring brick.


2. The quality of the self-baked carbon brick is not good, and the residual shrinkage rate after roasting is too large, resulting in cracking of the bottom of the furnace.


The pre-baked carbon bricks have undergone a shrinking process in the process of pre-baking, and the self-baked carbon bricks are processed from the green body to the graphitization process in the ore furnace, so the shrinkage of the self-baked carbon bricks is greater than that of the pre-baked carbon. Bricks, if the self-baking carbon bricks are of poor quality, the residual shrinkage after burning is too large, the lining will be cracked, and the infiltration of molten iron will cause the bottom of the furnace to burn through.


The quality inspection of self-baked carbon bricks should be carried out in strict accordance with the YB2805-2006 standard, especially the inspection of residual shrinkage must be carried out.


3, easy to oxidize when baking charcoal brick oven


Since the self-baked carbon bricks are not subjected to pre-calcination, the oxidation resistance and the resistance to slag erosion are poor. The oxidation temperature generally occurs between 500 and 800 °C. The oxidation of carbon bricks must have three conditions, easily oxidized raw materials, temperature, and oxygen. In the oven, these three conditions are available in the submerged arc furnace, so the carbon brick oxidation accident is likely to occur in the oven stage.


In order to prevent the oxidation of the carbon bricks in the general oven, the protective layer should be brushed on the outside of the carbon bricks. A protective layer of refractory bricks can be built on the outside of the carbon bricks, and the effect is good.


4. The temperature at the bottom of the submerged arc furnace is too high, and the conductivity is too large, which is not conducive to the smelting operation.


The raw materials used in self-baking carbon bricks are better than pre-baked carbon bricks. The thermal conductivity of self-baked carbon bricks is greater than that of pre-baked carbon bricks. Especially after graphitization of self-baking carbon bricks, the temperature of the bottom of the submerged arc furnace is significantly higher. For pre-baked carbon bricks. The conductivity of the self-baked carbon bricks is also significantly better than that of the pre-baked carbon bricks. The increase in the bypass current of the furnace bottom will increase the electricity consumption of the smelting, and the temperature of the carbon bricks at the bottom of the furnace will also increase, which is not conducive to normal smelting operations.


In order to avoid the high temperature at the bottom of the furnace and reduce the conductivity of the carbon brick at the bottom of the furnace, the lowermost layer of self-baking carbon bricks in the bottom of the furnace can be changed into light carbon bricks, or a layer of 50 mm cold can be hit between the layers of the carbon bricks. Paste.


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