In the experiment, the medium frequency coreless crucible induction furnace is selected for the melting of gray cast iron. The maximum refining capacity of the electric furnace is 50kg, and the crucible is acid silica sand crucible. Before the experiment, put the weighed raw pig iron and scrap steel into the furnace and heat them. Do a good job in slag removal during the heating process; Hot metal outlet temperature shall be controlled between 1500-1550 ° C; In the process of pouring molten iron out of the furnace into the ladle, rare earth is added by flow metamorphism; Hot metal pouring shall be carried out as soon as possible after deterioration, and the pouring temperature shall be controlled at 1400-1450 ° C; After the sample is naturally cooled to room temperature, box it, clean the surface of the sample, mark it, and record the experimental parameters.
The lining of acid induction furnace adopts silica sand as refractory, and the binder used is generally borax and water glass. The composition of silica sand shall meet the following requirements: silica is greater than 99%; Oxide less than 0.5%; Calcium oxide less than 0.25%; Alumina less than 0.2%; And other trace oxides. Boric acid shall meet the following requirements; Boron oxide greater than 98%; The particle size is less than 0.5mm. The proportion of furnace building materials is shown in the table.
Furnace lining knotting includes wet knotting and dry knotting: the so-called wet knotting refers to knotting by adding binder such as water, water glass, brine or tar into the furnace lining knotting material. As the knotting material contains certain moisture, it has less dust and good formability during construction. However, wet knotting has a series of disadvantages; The knotted lining material is not dense enough, and the fire resistance of the lining decreases; The drying of furnace lining takes a long time; When the moisture in the furnace lining is gasified, the insulation performance of the inductor decreases. Poor handling often leads to ignition and breakdown between boxes, and may also cause grounding short circuit. Dry knotting is adopted in this furnace, that is, borax is added as binder instead of water in the knotting material of furnace lining.
After the furnace lining is knotted, it shall be naturally dried first and then baked. The baking method can be fire or power on. Generally, the baking time shall not be less than 1 hour, and it shall be completely dried without cracking.