Method for performing pre-desiliconization on molten iron by utilizing CAS-OB refining furnace

Abstract

The invention discloses a method for performing pre-desiliconization on molten iron by utilizing a CAS-OB refining furnace. The method comprises the following steps of performing desiliconization treatment on molten iron by utilizing the existing CAS-OB refining furnace of a steel plant, providing low-silicon molten water for a converter or an electric furnace. The special process is as follows: performing slagging-off treatment on the molten iron by adopting a special high-temperature-resistant magnesia carbon brick molten iron tank for desiliconization, blowing oxygen gas or air by utilizing a spray gun above an immersion cover of the refining furnace, controlling the flow rate to 5-10Nm<3> / h.t, stopping blowing gas from the top spray gun when a slag layer reaches 30-80mm, opening a bottom-blowing gas valve to blow gas and stir, wherein the gas flow rate is 80-100Nm<3> / h; descending the cover after removing the slag layer, blowing oxygen gas or air by adopting the spray gun above the immersion cover to control the flow rate to 5-10Nm<3> / h.t, and transporting the molten iron to a slag removing position to remove the slag. According to the method disclosed by the invention, desiliconization is performed on the molten iron by utilizing the original refining furnace of the plant, so that a great deal of equipment investment cost and the occupied space are saved, and efficient low-cost production of low-silicon molten iron is realized.

Description

technical field [0001] The invention belongs to the technical field of pretreatment of molten iron, and in particular provides a method for producing low-silicon molten iron using a CAS-OB refining furnace. Background technique [0002] Desiliconization of hot metal is an important part of hot metal pretreatment. High silicon content in hot metal will bring adverse consequences to the normal operation of the converter and increase the cost of steelmaking. Reducing the silicon content in molten iron can reduce the smelting burden of the converter, reduce lime consumption, and realize steelmaking with less slag; promote the dephosphorization reaction in advance in the early stage of blowing, which will help improve the dephosphorization rate of the converter and create conditions for realizing efficient steelmaking . Practice has proved that when the silicon content of molten iron is removed from more than 0.6% to less than 0.2% by pre-desiliconization treatment of molten iro...

AI Technical Summary

Problems solved by technology

Although the "three desiliconization stations" can realize the desiliconization of molten iron, its disadvantages are that it requires a lot of equipment, large investment, large floor area, complex process, and large heat loss.

For example, document 2 ("Industrial Test of Desiliconization of Hot Metal by Slag Washing Method", Zhang Jiexin et al., Steelmaking, Volume 28, No. 2, Pages 44-47), discloses a method for desiliconization of hot metal by slag washing method. Desiliconization of molten iron can be achieved by adding desiliconization agent in the tapping process without additional equipment investment, but its disadvantage is that the desiliconization rate is low, and the desiliconization rate is only 52.69%; the consumption of desiliconization agent is high, and the desiliconization agent The consumption is more than 30kg / t; the desiliconization process is easy to produce foam slag, and the foam slag is easy to overflow if the control is not good

However, due to the high carbon content of molten iron, the CAS-OB refining furnace does not use a set of special process flow for desiliconization by blowing oxygen, which is prone to splash accidents. Therefore, no one has used the CAS-OB refining furnace for desiliconization of molten iron so far. processing technology

In addition, ordinary hot metal tanks usually use refractory bricks with low refractoriness, and the high temperature generated during oxygen blowing desiliconization will severely corrode the refractory bricks, which is also a factor that limits the desiliconization of molten iron in the CAS-OB refining furnace