Molten iron desulfurizing agent, preparation method thereof and desulfurization method using molten iron desulfurizing agent

Abstract

The invention discloses a molten iron desulfurizing agent, a preparation method thereof and a desulfurization method using the molten iron desulfurizing agent. The molten iron desulfurizing agent contains the following ingredients in percentage by weight: 55 to 70 percent of CaO, 5 to 20 percent of Al2O3, 2 to 4 percent of SiO2, 2 to 15 percent of MgO and 2 to 10 percent of CaF2. According to the invention, the molten iron desulfurizing agent is sprayed onto molten iron for desulfurizing, N2 is used as a powder-carrying gas, and the desulphurizing slag is melted based on the dynamic conditions of the gas and the physical heat of the molten iron, thus the desulfurization purpose is achieved; and after the desulfurization and slagging off treatment, the sulfur content of the molten iron can be reduced to below 0.006%.

Description

technical field [0001] The invention relates to a desulfurizing agent, in particular to a molten iron desulfurizing agent and a desulfurizing method using the desulfurizing agent. Background technique [0002] Hot metal pretreatment technology means that in the process of using hot metal as raw material for steelmaking, the hot metal is pre-desulfurized, dephosphorized, desiliconized, etc., to remove harmful elements such as sulfur, phosphorus and alloying element silicon in the hot metal, and to improve the quality of the molten iron. To achieve the purpose of improving the production rhythm of steelmaking, the cleanliness of molten steel and realizing smelting with less slag. Among the hot metal pretreatment technologies, the desulfurization pretreatment method outside the furnace is the most common. Because the pretreatment desulfurization in the molten iron tank is cheaper and more effective than the desulfurization in the steelmaking furnace or refining furnace, so the...

AI Technical Summary

Problems solved by technology

[0004] The main disadvantages of the pure granular magnesium injection method are: The price of passivated granular magnesium is more expensive, more than 30,000 yuan per ton; Desulfurization slag is thin and difficult to remove. The resulting desulfurization product is MgS. If the desulfurization slag is not removed and enters the converter for steelmaking, MgS will decompose under the high temperature conditions of steelmaking and cause molten steel to resulfurize; Since the melting point of magnesium is 650°C, the boiling point is 1100°C, and the temperature of molten iron is as high as 1300°C, a large amount of magnesium is volatilized and sublimated at the temperature of molten iron, and the utilization rate and yield are low.

Its disadvantages are: Compound injection equipment is more complex and has a higher failure rate; The lime density is small, the volume of the spray tank required is large, the floating time in the molten iron is fast, the desulfurization time is short, and the utilization rate is poor; Lime has a high melting point of 2580°C and cannot be melted at the temperature of molten iron. A large amount of active lime cannot be effectively utilized, which increases production costs

CaC 2 The main disadvantage of the desulfurization method is that CaC 2 It is easy to spontaneously ignite in contact with oxygen in the air, and the safety of storage and use is poor, so it is less used

[0006] Except above main technology, the Chinese patent application that application number is 200810137867.6 discloses a kind of compound type molten iron desulfurizer and preparation method thereof, the Chinese patent application that application number is 01114232.4 discloses a kind of composite type molten iron desulfurizer, and application number is The Chinese patent application of 200610018700.9 discloses a composite type molten iron desulfurizer; the essence of the above-mentioned several desulfurizers is to use lime and magnesium powder as the main raw materials, add some slag such as fluorite or other metals such as aluminum, and carry out mechanical stirring and mixing. Formed a mixture containing lime, magnesium powder, fluorite, aluminum powder and other substances, because the physical and chemical properties of the lime, magnesium powder and other substances in the mixture have not changed, such as the melting point of lime is still 2580 ° C, magnesium The melting point of the powder is still 650°C, the boiling point is still 1100°C, after the mixture enters the molten iron, there are still problems such as difficult melting of lime and vaporization and sublimation of magnesium powder, low utilization rate of desulfurizer, high cost, etc. application performance