Reinforcement of Steel Making Productivity at Kashima Steel Works

by Takanori Endo, Takanori Miyazawa, Hiroaki Yamazoe, Kouzou Oota, Jun-Ichi Tani

Publisher - Sumitomo Metal Industries, Kashima, Japan

Category - General Novel

Increase of the productive capacity is one of the most important current issues in Kashima Steel Works. Basic concept of Kashima Steel Works is Full-Time, Full-Capacity Operation. Two main countermeasures have been carried out to increase steelmaking productivity with minimum working equipments. One is reorganization of continuous casters. Two casters were revamped and one caster was closed at No.1 Steelmaking Plant, and one new caster was constructed at No.2 Steelmaking Plant. By this reorganization, all casters have become vertical bending type and number of strands has decreased to 6 from 7. The productive capacity has 17% increased by shortening preparation time and increasing casting speed. The other main countermeasure is reinforcement of refining and casting process of No.2 Steelmaking Plant. KR desulfurization process was introduced instead of conventional injection method. Desulfurization time was successfully reduced by the high reaction efficiency of mechanical stirring. BOF oxygen blowing speed at the first stage of refractory life increased by 8~13% with optimum 5-hole lance nozzle. And after the first stage, cavity volume related to spitting accumulation rate and BOF-dynamic-model were adjusted optimally. At the result, the blowing time after the first stage was reduced for 1 minute. Electro-Magnetic-Brake (EMBr) mould was installed at NO.3 slab caster to raise casting speed. EMBr can suppress molten steel flow in the mould and control mould level fluctuations. Inclusions and bubbles are controlled in the surface layer of slabs. As a result, high surface quality coils are produced at high speed casting. By carrying out above-mentioned countermeasures, output 8.3million tons per year have been realized.

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