Damping down method for blast furnace with poor hearth activity

Abstract

The invention relates to a damping-down method for a blast furnace with poor hearth activity. The damping-down method for the blast furnace with the poor hearth activity comprises the following steps that 1) the binary alkalinity of final slag is adjusted within one smelting period before blast furnace damping-down, so that the binary alkalinity of the final slag is reduced to 1.00-1.10, and the flowability of the final slag is improved; 2) coke needing to be added before damping-down of the blast furnace is not intensively added, and in 0.6-1 smelting period before damping-down of the blast furnace, the amount of the coke needing to be added is averagely distributed into each batch of coke in a mode of increasing the ratio of coke entering the furnace; (3) the blast furnace damping-down is advanced by 0.5-0.6 smelting period, the the ratio of the coke entering the furnace is increased again, the coke increased at the moment is distributed to the center of the blast furnace in a fixed-point mode in the form of tank coke, it is guaranteed that the coke falls to the position of a furnace bosh or a furnace bosh during damping-down, and the coke amount of the center of the blast furnace is increased; and (4) in 0.4-0.5 smelting period before damping-down of the blast furnace, the coal injection amount is adjusted according to the furnace temperature, or coal injection is stopped, and the Si content of molten iron before damping-down of the blast furnace is controlled to be 0.3%-0.4%. The ventilation capacity of a center stock column is improved, airflow is guided to develop towards the center, and rapid recovery after damping-down of the blast furnace with the poor hearth activity is achieved.

Description

technical field [0001] The invention relates to the field of iron and steel metallurgy, in particular to a blast furnace shutdown method with poor hearth activity. Background technique [0002] For blast furnaces with poor air permeability and liquid permeability of the hearth furnace core dead material column, the recovery of air supply after the wind shutdown has always been a major problem for ironworkers. The cylinder is in the process of having no heat source and consuming its own heat all the time. The slag iron in the dead material column of the furnace core is further condensed, which further weakens the air permeability of the dead material column of the furnace core, and the air volume and air pressure are low in the initial stage of air supply. , it is difficult for the airflow to get through the central channel, and often with the addition of air, the airflow is forced to flow to the edge, resulting in an increase in the temperature difference of the furnace body...

AI Technical Summary

Problems solved by technology

[0002] For blast furnaces with poor air permeability and liquid permeability of the hearth furnace core dead material column, the recovery of air supply after the wind shutdown has always been a major problem for ironworkers. The cylinder is in the process of having no heat source and consuming its own heat all the time. The slag iron in the dead material column of the furnace core is further condensed, which further weakens the air permeability of the dead material column of the furnace core, and the air volume and air pressure are low in the initial stage of air supply. , it is difficult for the airflow to get through the central channel, and often with the addition of air, the airflow is forced to flow to the edge, resulting in an increase in the temperature difference of the furnace body, the root of the reflow zone moves up, the feeding becomes poor, the material frequently collapses and slips, and the air volume and air pressure of the blast furnace appear. Repeatedly, air supply recovery timed out

[0003] In the past, when the blast furnace is shut down, it is generally used to add canned coke to reduce the coke load. The basicity of the slag is generally required to be between 1.10-1.20, and the Si content of the molten iron is controlled at 0.5-0.6%. There are four disadvantages when the blast furnace is shut down: First, the coke used to reduce the load in the blast furnace is concentrated into the blast furnace through the coke tank, and it is easy to cause large fluctuations in the furnace temperature when it reaches the hearth, causing rapid heat recovery and deterioration of gas permeability , which affects the smooth flow of the blast furnace; secondly, the normal distribution system is adopted for the can coke in the wind-off material. According to the proportion of the central coke, the amount of coke distributed into the center of the blast furnace is relatively small, which cannot well guide the airflow to the center. Third, the furnace temperature control before the wind shutdown is too high, which is not conducive to recovery; fourth, the final slag basicity is controlled too high, which will easily lead to poor fluidity of slag and iron; therefore, the original shutdown material is not suitable for blast furnaces with poor hearth activity. wind recovery