Repair of lining of medium frequency melting furnace: When there are multiple damages on various parts of the medium frequency furnace lining, repair must be carried out to prolong the service life of the furnace lining and prevent accidents caused by lining damage. The repair parts and methods for the furnace lining are as follows:

(1) Repair of cracking or damage at the joint between the tap hole refractory and the furnace wall. It can be repaired by ramming unshaped refractory. If the repair area is relatively large, the repaired part shall be dried with charcoal or other fuels.

(2) Repair of side wall cracking Generally, cracks below 1mm do not need repair and can keep working; cracks over 1mm, especially horizontal cracks, must be repaired. You can sift the furnace-building refractory that is evenly mixed with boric acid, then fill the crack with iron wires and other tools. After filling, smooth the surface with wet mixed sand added with sodium silicate.

(3) Repair of side wall damage or small-scale erosion After removing furnace slag and residual iron, coat the area with sodium silicate. Then ram and repair with mixed refractory added with 5%-6% sodium silicate, or repair with Al₂O₃ unshaped refractory. If the erosion area is relatively large, repair it with a mold.

(4) Repair of burning loss or damage at the bottom and inclined part of the side wall For furnace bottom repair, use the medium frequency furnace refractory evenly mixed with the same amount of boric acid as that for new furnace building, then ram and compact it. For repairing the inclined part of the side wall, you need to install a mold whose outer diameter is 50-60 mm smaller than the furnace diameter and height is about 100 mm higher than the damaged part. Ram with a vibrator, the compacted thickness of each layer is 20-30 mm. Roughen the surface of one rammed layer before ramming the next layer, until the material is 10 mm higher than the mold, then trim the upper surface into a certain slope.