Desulfurization process of molten iron pretreatment by composite injection of calcite and passivated granular magnesium

Abstract

The invention provides a hot metal pretreatment desulfurization technology with calcite and passivation particle magnesium injected in a composite mode and belongs to the field of the steel industry. The calcite is used for replacing lime in existing hot metal pretreatment desulfurizing agents, and the composite-injection calcite and the passivation particle magnesium of desulfurizing agents are prepared anew. The proportion that the granularity of the calcite is lower than 1mm by cracking the calcite is larger than 100%, during injection, the material ratio of the calcite to the particle magnesium is controlled between 6:1 and 9:1, the feeding speed of the particle magnesium is controlled to be 6-8kg / min, the feeding amount of the calcite is controlled to be 41.5-54kg / min, overall feeding speed is controlled to be 60kg / min, a straight-drum spraying gun is used, the distance between the head of the spraying gun and the bottom of a ladle tank is set to be 300mm, and the powder-gas ratio during a desulfurization injection process can reach 120kg / m<3>. According to the hot metal pretreatment desulfurization technology, the using rate of passivation magnesium is improved, desulfurization efficiency is improved, loss of the particle magnesium is lowered, and desulfurization cost is lowered. The calcite is natural minerals, after the qualified granularity of the calcite is achieved by cracking the calcite, the calcite can be directly used, extra machining cost is of no need, and the price is one-fourth of the lime.

Description

technical field [0001] The invention belongs to the field of steelmaking industry. Background technique [0002] At present, there are three main desulfurization technologies for hot metal pretreatment, KR method, single blowing granular magnesium, and composite blowing magnesium-based desulfurizer method. The injection method is a desulfurization method in which the desulfurization powder is sprayed into the deep part of the molten iron with a spray gun using gas as a carrier to stir the molten iron and the desulfurizer to fully mix. Composite injection is a desulfurization process that uses two or more desulfurization powders in their own dedicated powder spray tanks, weighs them, and then transports them to the same spray gun for injection. Its characteristics are that the proportion of desulfurization powder can be flexibly adjusted according to the needs of the site, low powder consumption, stable control, flexible adjustment, high-efficiency equipment, less splashing,...

AI Technical Summary

Problems solved by technology

[0004] At present, the composite injection method mainly uses lime and granular magnesium as desulfurizers, but the fluidity of lime is poor, and it is easy to "bridge" and block materials in the material tank. At the same time, lime is very easy to absorb water and deliquescence, and the Ca(OH) 2 , not only affects the desulfurization effect, but also pollutes the environment

At the same time, during the lime desulfurization process, Si in molten iron is oxidized to form SiO 2 , SiO 2 Will react with CaO to generate 2CaO.SiO 2 , the corresponding amount of effective CaO is consumed, and dense 2CaO.SiO is formed on the surface of lime powder 2 It hinders the diffusion of [S] to CaO powder, which affects the desulfurization speed and desulfurization efficiency

[0005] In order to solve the problem of lime deliquescence and deterioration, the lime is passivated with silicone oil to prevent lime deterioration and deliquescence, but the passivation process is difficult to control, and additional costs are required to purchase passivation equipment, resulting in high raw material prices