Low-carbon ultralow-sulfur pure iron smelting method

Abstract

The invention relates to a low-carbon ultralow-sulfur pure iron smelting method. The process route comprises the steps of molten iron pretreatment, converter double-slag smelting, RH decarburization, LF dephosphorization, molten steel slagging-off, LF desulfurization and continuous casting. The method specifically comprises the following steps: 1) molten iron pretreatment desulfurization: the S content of molten iron before pretreatment is less than or equal to 0.040%; s is required to be less than or equal to 0.002% after molten iron pretreatment desulfurization; (2) converter double-slag smelting is carried out to control resulfurization, specifically, special pure iron waste steel is added into a converter, oxygen blowing is started, a slagging material is added after oxygen blowing is carried out for 40-50 s, oxygen blowing is carried out for 4-5 min, the oxygen accumulation amount of oxygen blowing is 3500-4500 standard cubic meters, and a gun is lifted to discharge slag; 3) LF desulfurization: after molten steel slagging-off is finished and argon blowing is confirmed to be normal, carrying out oxygen determination operation; the top slag is strongly modified and desulfurized, and it is guaranteed that the outbound S is controlled to be 10 ppm or below; atomized aluminum powder is used in the middle and later periods of LF desulfurization, so that it is guaranteed that outbound Alt is not higher than 0.010%; and 4) controlling the resulfurization by a casting machine. According to the invention, after RH decarburization, LF desulfurization is carried out, and then the desulfurization is directly carried out on a machine, so that the resulfurization in the RH treatment process is avoided, and the ultralow sulfur control that the sulfur content of a finished product is less than or equal to 0.001% is ensured.

Description

technical field [0001] The invention relates to the technical field of iron and steel smelting, in particular to a low-carbon ultra-low-sulfur pure iron smelting method. Background technique [0002] Pure iron is an iron alloy with very low carbon content, which has excellent properties such as low coercive force, good thermal conductivity and electromagnetic properties, soft texture, and good toughness. At present, the purity of pure iron that has been industrialized and applied is more than 99.6%. It is mainly used as iron-based raw materials for smelting high-temperature alloys, heat-resistant alloys, precision alloys, and maraging steels. [0003] Ultra-low sulfur pure iron has high resistance to hydrogen-induced cracks and sulfur stress cracks. It is required to control the sulfur content in steel to ≤50ppm, so as to ensure that the pure iron reaches the level of ultra-low impurity elements to meet the requirements of secondary hardening steel, Production of precision ...

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Problems solved by technology

BaO is a highly toxic toxic substance, which is harmful to human health if inhaled or ingested, and is not conducive to on-site production