JPS6119708A - Blast furnace desiliconization operation method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a blast furnace operating method that can simultaneously remove silicon from hot metal and adjust the temperature of the hot metal to an appropriate value.

(B) Conventional technology Conventional methods for adjusting the silicon content in hot metal to a low level include a method of injecting oxides into the hot metal using a hearth gutter, a tobbed car, a ladle, etc. to desiliconize it, and a method using a hearth in a blast furnace. There is a method for desiliconizing by blowing oxides into hot metal stored in a hot metal basin at a temperature of ℃.

In the method of injecting oxides outside the blast furnace, the silicon content is reduced to 0.0
In principle, it is possible to reduce the amount to 1% or less, but it may worsen the unit consumption of refractories or reduce the amount of heat and carbon generated during the desiliconization reaction.
This method has the drawback of high processing costs due to the inability to utilize O gas effectively. On the other hand, in the desiliconization method in which oxide is injected into the blast furnace, the silicon content is generally limited to about 0.30%.

For this reason, in recent years, a desiliconization method has been developed in which only oxygen is blown into the hearth sump, increasing the desiliconization effect.

This method of blowing oxygen into the blast furnace reduces the silicon content to 0.
It is possible to reduce it to 0.1% or less. However, S:L + 02-+ (5tOz) + 20,8
Due to the exothermic reaction with 10,000 K cal/V, m o IJ,
The temperature of the hot metal rises too high, which causes problems such as accelerated wear of the hearth bricks, shortening the lifespan of the blast furnace, and deteriorating the ventilation of the blast furnace due to hanging shelves.

(c) Problems to be solved by the invention The present invention aims to eliminate these drawbacks of the conventional method, and provides a blast furnace operating method that can increase the desiliconization efficiency by adjusting the hot metal temperature to an appropriate value. I will provide a.

(d) Means for solving the problems In the present invention, as means for solving the above problems,
In a blast furnace operating method in which oxygen is injected from outside the blast furnace into the hearth sump inside the blast furnace at a pressure higher than the furnace internal pressure to adjust the silicon content in the hot metal to a low level, air is substituted for part of the oxygen. Alternatively, the temperature of the hot metal can be adjusted to an appropriate value by injecting coolants such as scale and ore powder.

(E) Embodiment As shown in FIG. 1, oxygen, air, and other coolants can be selectively mixed and injected into the hot metal 11 in the hearth sump of the blast furnace 1 through the nozzle 4. A part of the oxygen to be blown into the furnace is replaced by air or coolant. Scale, fine ore, iron oxide dust, etc. are used as a coolant.

During blowing, the temperature of the hot metal is measured with a thermometer 2, and the measured value is input into the control device B, which has preset a predetermined mixing ratio and blowing amount, and the blowing gas is controlled based on this measured value and the set value. Allows you to select whether to open or close the valve.

Since the temperature of the hot metal dripping into the hearth can be estimated by a computer model system, the amount of injection into the furnace is feedback-controlled using this data.

Furthermore, sample analysis is quickly performed during tapping, data on the composition and temperature after desiliconization is obtained, and the data is input to the control device B to maintain the low stable state of desiliconization and the stability of the hot metal temperature.

(f) Effect When air is used as a substitute for oxygen in the method of the present invention, N2 contained in the air does not react in the furnace.
Functions as a coolant in hearth reactions. therefore,
As shown in FIGS. 2 and 6, the increase in hot metal temperature at the same desiliconization value is suppressed to a lower temperature than in the case of using only oxygen.

As the mixed gas used in the method of the present invention, in addition to the above-mentioned air and coolant, CO2-rich heating furnace or hot blast furnace exhaust gas may be used.

CO2−)−Fe−+FeO×Co FeO+Si
→Fe-1-(SiO2) Desulfurization and dephosphorization are also possible by injecting quicklime, soda ash, fluorspar, etc. together with scale as a coolant.

(g) Effects According to the method of the present invention, the silicon content in the hot metal can be adjusted to a low level while controlling the temperature of the hot metal in the furnace to an appropriate value. It becomes possible to produce high-grade pig iron without progressing wear and tear on the furnace body. It is also convenient because desulfurization and dephosphorization treatments can be performed at the same time by blowing quicklime or the like at the same time.

FIG. FIG. 2 and FIG. 6 are diagrams showing the relationship between the hot metal temperature and the desiliconization state, comparing the method of the present invention and the conventional method.

1: Blast furnace 2: Thermometer

Claims (1)

[Claims] In a blast furnace operation method in which oxygen is blown into the hearth sump of a blast furnace, a part of the oxygen is replaced with air and/or a coolant such as iron oxide to perform desiliconization and adjust the hot metal temperature. Characteristic blast furnace desiliconization operation method.