Ladle Furnace Cover - LF

Ladle arc refining furnace is an out-of-furnace refining technology that uses arc heating under vacuum conditions. It is refined by placing the molten steel initially smelted in a general steelmaking furnace in a special ladle.

Ladle furnace is an important metallurgical equipment used to refine molten steel melted in primary furnaces (electric arc furnace, open hearth furnace, converter), and can adjust the temperature of molten steel, process buffer, and meet continuous casting and rolling.

Composition

It mainly includes ladle, ladle furnace cover, arc heating system, vacuum system and feeding device, etc.

Features

Features of Ladle Furnace Cover

The ladle furnace cover is mainly used for sealing the ladle mouth, maintaining a strong reducing atmosphere in the furnace and preventing the molten steel from dissipating heat. There is a water-cooled furnace cover on the ladle mouth. 

The inner side of the furnace cover is poured with refractory material. The furnace cover is equipped with a lifting mechanism according to the process requirements.

Arc Heating

The molten steel is heated by arc light generated between the graphite electrode and the molten steel. Because the electrode is inserted into the foam slag or slag through the furnace cover hole, it is called submerged arc heating. 

This heating method has less heat dissipation, reduces heat radiation and erosion of the furnace lining by arc light, and can stabilize the current. The temperature rise rate of molten steel can reach 4°C/min.

Vacuum Dystem

It consists of vacuum furnace cover, vacuum pump, vacuum exhaust pipe and dust removal equipment. An air or nitrogen inlet is provided on the vacuum exhaust pipe to adjust the vacuum degree in the furnace or inflate to break the vacuum at the end of the refining process. 

The top of the vacuum furnace cover is provided with a vacuum exhaust port and a peep hole, and a sealed water-cooling device is provided at the joint with the ladle mouth, and a vacuum furnace cover lifting mechanism. The vacuum pump adopts multi-stage steam jet pump.

Feeding Device

A slagging agent and an alloy feeding port are respectively arranged on the ladle furnace cover and the vacuum cover. 

A hopper is equipped on the upper part of the furnace cover or vacuum cover, and the charge weighed by the electronic scale enters the LF through the chute and the charging port.

In order to smelt ultra-low carbon stainless steel, a hole is opened at the vertical center of the ladle furnace cover for the oxygen supply lance to blow oxygen and reduce carbon to the molten steel.

Refining Process

Including slagging, heating, argon stirring, slag composition adjustment, liquid steel composition adjustment, vacuum treatment and heat preservation, etc.

The quality of the primary molten steel is related to whether the refining furnace can successfully achieve the purpose of refining. Therefore, the phosphorus content of the primary molten steel is required to be less than 0.015%, and different degrees of final deoxidation are carried out when the steel is tapped from the primary smelting furnace.

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