It is used to seal the ladle mouth, maintain a strong reducing atmosphere in the furnace and prevent the molten steel from radiating. The ladle mouth is provided with a water-cooled furnace cover. Refractory material is poured inside the furnace cover. The furnace cover is equipped with a lifting mechanism according to the process requirements. Arc heating uses the arc generated between graphite electrode and molten steel to heat molten steel. Because the electrode is inserted into the foam slag or molten slag through the hole of the furnace cover, it is called submerged arc heating. This heating method has less heat dissipation, reduces the thermal radiation and erosion of arc light to the furnace lining, and can stabilize the current. The heating rate of molten steel can reach 4℃/min.

The vacuum system consists of vacuum furnace cover, vacuum pump, vacuum exhaust pipeline and dust removal equipment. An air or nitrogen inlet is arranged on the vacuumizing pipeline to adjust the vacuum degree in the furnace or inflate to destroy the vacuum at the end of refining treatment. The top of the vacuum furnace cover is provided with a vacuum exhaust port and a peephole, and the joint with the ladle mouth is provided with a sealed water-cooling yellowing device and a vacuum furnace cover lifting mechanism. The vacuum pump adopts multistage steam jet pump.

The charging device is provided with a slag-making agent and an alloy inlet on the furnace cover and the vacuum cover respectively. The furnace cover or vacuum cover is equipped with a hopper, and the burden weighed by an electronic scale enters the ladle furnace through a chute and a charging port. In order to smelt ultra-low carbon stainless steel, the vertical center of the vacuum furnace cover is provided with a hole for the oxygen lance to lift, so as to blow oxygen to the molten steel to reduce carbon.

The refining process includes slag discharge, heating, argon stirring, slag composition adjustment, molten steel composition adjustment, vacuum treatment and heat preservation. The quality of primary steelmaking liquid is related to whether the refining furnace can successfully achieve the refining purpose. Therefore, it is required that the phosphorus content in the initial steelmaking liquid should be lower than 0.0 15%, and the final deoxidation should be carried out in different degrees when the initial steelmaking furnace is tapped.