Partially calcined limestone for rapid slagging of converter and preparation method thereof

Abstract

The invention relates to partially calcined limestone for rapid slagging of a converter and a preparation method of the partially calcined limestone. A surface lime layer of the prepared partially calcined limestone is high-activity lime, and an inner core component of the prepared partially calcined limestone is calcium carbonate. The preparation method comprises the following steps: taking limestone containing calcium carbonate as a raw material, crushing, cleaning and screening to obtain blocky limestone of 15-20mm, preserving heat in a heating furnace of 200-300 DEG C for 2-3h, and performing calcining in a rotary kiln of 3-6 revolutions / min at 800-900 DEG C for 0.5-0.8 h to obtain the partially calcined limestone. When the prepared partially calcined limestone is applied to a converter for slagging, the dissolution process avoids the stagnation stage existing in the initial dissolution stage when limestone is directly used for slagging, and the initial dissolution rate is higher; when the residual amount of CO2 is 25-30% by mass, the heat required for decomposition is reduced by more than 32%, so that the heat balance of the converter is favorably maintained, and the application range of slagging by applying part of calcined limestone can be expanded to produce steel with higher carbon content.

Description

technical field [0001] The invention relates to a partially calcined limestone for rapid slagging in a converter and a preparation method thereof, belonging to the technical field of slag making in a converter steelmaking process. Background technique [0002] In the process of converter steelmaking, in order to achieve the purpose of dephosphorization in a large amount in the early stage, it is required to quickly produce slag with a certain alkalinity, oxidation resistance and good fluidity. For hundreds of years, the traditional method is to use calcined pure lime to make slag. Lime is the main slagging agent for converter steelmaking. It is made of limestone fired under certain conditions. [0003] Improving lime activity is beneficial to accelerate the dissolution of lime in converter slag, but the effect is limited. Since the lime is dissolved in the converter slag, a calcium silicate isolation layer will be formed on the surface, which seriously hinders the mass tran...

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Problems solved by technology

However, in practice in recent years, it has been found that limestone instead of lime also has some shortcomings. Because the dissolution process of limestone first undergoes a decomposition process, the decomposition of limestone is an endothermic reaction, and the initial furnace temperature of the converter is relatively low, so limestone is in the process of dissolution. There will be a period of stagnation at the beginning, so that the initial dissolution rate of limestone is slow

More importantly, a large amount of heat absorbed by the limestone decomposition process will affect the heat balance of the converter smelting process, and more carbon in molten steel needs to be consumed to generate heat, which makes the method of directly putting limestone into slag only suitable for smelting steel with low carbon content One, in the case of limited excess heat in the converter bath, the addition of too much limestone will also affect the reasonable addition of other slagging agents

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