VOD refining operation process 1: steel melting

Source: | Author:ChangXing Refractory | Published time: 1560 days ago | 1005 Views | Share:

a. LD converter as primary furnace

Pour the desulfurized molten iron, scrap steel and nickel (according to the specifications) into the converter for a decarburization. After the silicon, carbon and phosphorus in the molten iron are removed, the steel is tapped and slag is removed to prevent back phosphorus. Then, add high-carbon ferrochrome (according to specifications) into the inverted rotary furnace, and then conduct melting and secondary decarburization. The end point carbon should not be too low, otherwise the burning loss of chromium will be serious, usually controlled at 0.4% to 0.6%. The blowing temperature is kept above 1770℃, and the initial molten steel is poured into the ladle furnace.

b. Electric arc furnace as primary furnace

The charge is mixed with cheap high-carbon ferrochrome, with a carbon content of 1.5% to 2.0% (part of the stainless steel return material should be added, if all high-carbon ferrochrome is used, the carbon content after molten steel is as high as 2.0%) . The chromium content is mixed according to the upper specification limit to reduce the amount of low-carbon ferrochrome added in the initial stage of refining, and nickel is also mixed according to the specification requirements. Oxygen blowing in the electric arc furnace for decarburization to the range of 0.3% to 0.6%, the carbon content of the initial molten steel cannot be too low, otherwise it will increase the oxidation loss of chromium, but it should not be too high, otherwise, during vacuum oxygen blowing decarburization, If the carbon-oxygen reaction is too violent, it will cause serious splashing, lower the metal yield, and affect the operation rate. In order to reduce the burning loss of chromium in the primary molten steel, at the end of oxygen blowing, the primary slag is reduced and deoxidized to recover part of the chromium. After the initial molten steel is poured into the ladle furnace, all the slag should be removed. It is best to tap the steel with an eccentric furnace bottom.