Desilication agent for molten iron pretreatment and preparation method thereof

Abstract

The invention discloses a desilication agent for molten iron pretreatment. The desilication agent for molten iron pretreatment comprises hematite, limestone and sodium carbonate; the hematite, the limestone and the sodium carbonate comprise the following raw materials in percentage by weight: 10 to 20 percent of CaO, 50 to 80 percent of Fe2O3, 1 to 5 percent of NaO2, less than or equal to 4 percent of SiO2, less than or equal to 2 percent of MgO, less than or equal to 1 percent of F, and the balance of impurities. The desilication agent prepared by a preparation method provided by the invention has the characteristics of low unit consumption and high desilication efficiency; the desilication efficiency can reach 70 percent above; the content of silicon in molten iron can be reduced below 0.13 percent; and a basic condition is provided for smelting of high-quality steel.

Description

technical field [0001] The invention belongs to the technical field of iron and steel metallurgy, in particular to a desiliconizing agent for pretreatment of molten iron and a preparation method thereof. Background technique [0002] Due to the advancement of science and technology and the development of social economy, the metallurgical industry is required to provide as much high-quality steel as possible. Therefore, the content of harmful elements such as sulfur and phosphorus in steel must be strictly controlled. The traditional steelmaking process requires simultaneous desiliconization, dephosphorization and decarburization operations in the same molten pool, but the thermodynamic conditions of these reactions are contradictory and restricted by kinetic conditions, so it is difficult to achieve the desired effect. In the past, the silicon content of molten iron added to the converter was usually above 0.6%. The use of this high-silicon molten iron for steelmaking mainl...

AI Technical Summary

Problems solved by technology

Generally, the basicity of converter slag is between 3.0 and 3.5. For every 0.1% increase in the silicon content of molten iron, the amount of steel slag per ton will increase by 8 to 13kg. Too much slag will cause frequent adjustment of the oxygen lance position, and the aerodynamic conditions of oxygen blowing will deteriorate. , resulting in easy splashing during operation;

[0004] (2) Desulfurization and dephosphorization agents for steelmaking are mainly alkaline substances (lime, fluorite, etc.), and SiO brought by high-silicon molten iron 2 It will be preferentially combined with them, reducing the activity of alkaline substances, which is not conducive to the removal of sulfur and phosphorus;

[0005] (3) Converter slag contains a certain amount of iron oxide and iron beads, the amount of slag is large, and the iron loss will inevitably increase;

[0006] (4) The amount of slag is large, which aggravates the erosion and erosion of the furnace lining, especially the primary slag is highly acidic, and the erosion of the basic furnace lining is more obvious, which will shorten the furnace life and increase the consumption of furnace lining gunning materials;

[0007] (5) From the perspective of energy utilization in the ironmaking-steelmaking joint process, there is a serious waste in smelting high-silicon molten iron and then adding it to converter steelmaking

[0049] Based on the above theories, various types of desiliconization agents have been successively developed by various domestic steel mills, but all of them have certain disadvantages: Application No. 201210405527.3 "A method for pretreatment of desiliconization of molten iron" involves a desiliconization agent, its main The raw material is rolled steel oxide scale. The desiliconization agent can provide a certain oxidant, but there is no flux, and the content of calcium oxide CaO is low, which leads to its high melting point and difficult melting during use. When the kinetic conditions are insufficient, the final desilication efficiency is not high

[0050] The application number is 201010131644.6 "Molten Iron Desiliconization Agent and Method for Desiliconization of Hot Metal", which involves a desiliconization agent, which is composed of mixed acid iron oxide powder, shot blasting dust removal powder, stainless steel steelmaking dust removal dust and hot-rolled iron oxide scale. Good thermodynamic and kinetic conditions, but its mixed acid iron oxide powder, shot blasting dust removal powder and stainless steel dust removal powder contain a large amount of chromium oxide. Chromium oxide is a beneficial component for smelting stainless steel, but it is not suitable for other carbon steel, The smelting of high-quality steel grades has relatively large limitations

[0051] At the same time, the currently used desiliconization agents are all mechanically mixed with different oxidizing agents and fluxes. These desiliconization agents have the characteristics of high melting point and uneven composition, resulting in low desiliconization efficiency during trial use.

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