The working principle of the electric furnace with core-induction furnace with power frequency, which is referred to as core-induction furnace, is suitable for smelting and casting pure metals such as copper and zinc, etc. The furnace has the advantages of high thermal efficiency, high electrical efficiency, less metal burning loss, uniform stirring, stable furnace temperature and so on.But its furnace building technology is more complex, the replacement of production varieties need to wash the furnace.Configuration of induction furnace heating unit is inductor, most used one-way flow of section weld groove, the new type of large capacity induction furnace (45 t furnace configuration of 300 kw inductor) has adopt double melting trench flow type inductor, increase thermal efficiency at the same time, reduce the melting slag deposition within the trench, effectively prolong the service life of the inductor.The working principle of power frequency core induction furnace applies the principle of electromagnetic induction and the principle of current thermal effect.When the alternating current of power frequency passes through the induction furnace coil (induction body), the alternating magnetic field generated is transferred through the iron core to the secondary coil, namely the melting groove. The strong induction current in the melting groove is usually up to thousands of amps to tens of thousands of amps.The thermal effect of the electric current causes the groove to produce heat to melt the metal.Under the action of thermal convection and electromagnetic force, the heat in the groove is exchanged with the charge in the furnace, so as to heat the charge and melt the metal.

The furnace body of the zinc melting furnace is mainly composed of the furnace shell, the furnace cover, the slag picking door, the feeding mask, the zinc releasing mouth, the pouring mouth, the induction body, the refractory lining, etc., as shown in Figure 1.The furnace shell is in the form of steel structure, which is welded by channel steel and medium thick steel plate.The front of the furnace body is provided with a pouring mouth and the side is provided with a slag picking door and a zinc releasing mouth;Inductors are installed on both sides of furnace body and behind feeding hopper.A temperature measuring point is set in the front chamber of the furnace to monitor the temperature of zinc liquid.The furnace cover is composed of steel structure and cast lining of thermal insulation refractory. The furnace cover is provided with feeding port. The cathode zinc sheet is added from the feeding port to the lining of the furnace using energy-saving composite refractory materials, which is made of thermal insulation material, thermal insulation brick masonry and amorphous refractory materials cast.The furnace lining is poured into a smooth refractory wall of about 200mm, which can easily remove the zinc liquid and slag splashing on the wall during feeding, reduce the labor intensity, and improve the life of the furnace lining.The throat is also made of amorphous refractory castable so as to form a special-shaped structure and an inductor butt joint.

Power supply system - The electrical installation consists of a power cabinet, a low-voltage distribution panel and an operating table.The main power supply circuit consists of circuit breaker, self - coupling voltage regulator, reactor, capacitor, contactor and so on.Control loop intermediate relay, transfer switch and other components.It can supply power to each sensor independently.The output voltage of the auto-voltage regulator is adjustable.According to the change of furnace temperature, the supply voltage is adjusted by controlling contactor, so as to meet the needs of drying furnace, heat preservation, heating and melting zinc sheet.