High-purity molten cast iron nitrogen increasing agent and nitrogen increasing method for blast furnace smelting

Abstract

The invention provides a high-purity molten cast iron nitrogen increasing agent for blast furnace smelting. The high-purity molten cast iron nitrogen increasing agent is prepared from, by weight, 25%-30% of N, 10%-15% of Mn and 35%-55% of Si. The invention further provides a high-purity molten cast iron nitrogen increasing method for blast furnace smelting. The method comprises the following steps that S1, the nitrogen increasing agent is crushed and sieved, and then the nitrogen increasing agent and blast-furnace normal injection pulverized coal are mixed to be uniform in proportion to obtain a mixed injection coal material; and S2, the mixed injection coal material containing the nitrogen increasing agent is put into a coal injecting tank of a blast-furnace coal injection system and conveyed to a blast-furnace tuyere through an injection pipeline, and then enters a blast furnace through a tuyere coal injection gun. According to the high-purity molten cast iron nitrogen increasing agent and nitrogen increasing method for blast furnace smelting, the nitrogen increasing agent is injected and enters molten iron, so that the influence of a slag layer is avoided, and the molten iron nitrogen increasing environment is improved. Combined with a normal coal injection process, the nitrogen increasing agent is uniformly injected, the segregation phenomenon of the nitrogen increasing agent and the pulverized coal is not generated, the content of N in the molten iron can be significantly increased, the blast-furnace production process and equipment procedures are not changed, and the industrial production adaptability is high.

Description

technical field [0001] The invention relates to the technical field of blast furnace ironmaking, in particular to a nitrogen-increasing agent and a nitrogen-increasing method for blast furnace smelting high-purity pig iron molten iron. Background technique [0002] High-purity pig iron refers to pig iron with low content of Ti, Mn, S, P and other elements, and very little content of specific trace elements, which is specially used for the production of high-quality castings. At present, the smelting methods of high-purity pig iron mainly include oxidation method and concentrate method. The oxidation method refers to blowing molten iron with oxygen or air to remove Si, Mn, Ti, V, Cr, P, etc. from it. This process has no special requirements on blast furnace raw materials, and trace elements in pig iron can be controlled, but the process is complicated in technology, high in cost and low in output. The concentrate method is to control the amount of harmful elements entering ...

AI Technical Summary

Problems solved by technology

[0004] The existing high-purity pig iron smelting method can control and increase the temperature of molten iron, but it cannot increase the N content in molten iron, so Ti and N in the molten iron cannot be fully combined to precipitate more TiN and remain in the furnace, resulting in Ti in the molten iron stay high