Mastering steel production in the electric steelmaking shop at the Belorussian Metallurgical Plant

Abstract

The furnace is operated in both the manual and automatic regimes. The automatic system makes it possible to predict the temperature of the metal, calculate and add the slag-forming materials and deoxidizers to the furnace and ladle, and control the operation of the furnace transformer. A centrifugal fettling machine and a guniting machine, a device for feeding powdered material into the furnace, and a 3-ton-capacity charging machine are located on the shop working platfor~. The scrap preparation section (SPS), designed to process 780,000 tons of scrap a year, is equipped with a baling press with a minimum pressure of 21 MPa and three scrap shears with a cutting force of 12 MN (1200 ton-f). The capacity of these units in terms of the hourly output of 400  400  500 ~m bales is 25 tons for the shear and 20 tons for the press. A truck transports processed scrap from the section to the furnace bay in 80-m 3 cages. After the ferroalloys and slag-forming materials are crushed in a jaw crusher and screened at the warehouse, they are moved to receiving hoppers in the shop by an inclined conveyor. The materials then travel by chutes into the furnace through a hole in the roof, into the ladle during tapping, or into the degassing unit. Steel is made in the arc furnace by the single-slag method with partial deoxidation of the slag in the furnace with coke. Two steelmaking variants are alternated: with placement of the charge on a "dry" (cleaned Of slag and metal residues) furnace bottom for the first heat; with placement of the charge on a "bog" (on the slag and about I/i0 of the metal of the previous heat) for heats 2 through 12. The metallic charge is placed in the furnace in two loads (base and pile) of 60-65 and 40-55 tons, respectively. The furnace is turned on after inspection and fettling of the bottom and banks during cold-charging of the scrap on the "dry" bottom or, when necessary, guniting of the lining of the walls and panels during cold-charging of scrap onto the "bogf" The melting period is conducted with high voltages and a moderate active power of 50-55 ~# (Fig. i). Melting is speeded up by using wall-mounted oxyacetylene burners. Their operating regime is shown in Fig.