Multifunctional efficient rotary stirring powder spraying desulfurization blowing method

Abstract

The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a multifunctional efficient rotary stirring powder spraying desulfurization injection method, which is characterized in that carbon powder is added into injection powder, so that the fluidity of desulfurization powder is improved, the risk of blocking a powder channel in the powder injection process is reduced, molten iron is recarburized, the chemical latent heat of the molten iron is improved, and the desulfurization effect is improved. The activity coefficient of sulfur in the molten iron is increased, and desulfurization is promoted; on the other hand, hydrogen-rich gas such as hydrogen or natural gas or coke oven gas is adopted to replace nitrogen and argon to serve as carrier gas for injection, the injected gas reacts with oxygen in the molten iron, oxygen in the molten iron is reduced, desulfurization is promoted, and loss caused by the reaction of magnesium powder and oxygen in the molten iron is reduced; meanwhile, the blown-in gas directly reacts with sulfur in the molten iron, and the desulfurization effect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a multifunctional and efficient rotary stirring powder spraying desulfurization blowing method. Background Art

[0002] Hot metal pretreatment is an important process in steel production. Improving the desulfurization efficiency and enhancing its functions can play a positive role in the development of low-carbon steel production.

[0003] Rotary stirring powder spray desulfurization has the dual advantages of KR desulfurization and powder spray desulfurization, and has received more and more attention and research. However, due to the late development of this technology, there are still many related technical and engineering problems, the optimization and development of desulfurizers are still relatively small, and the metallurgical function is relatively simple, which is limited to molten iron desulfurization. At the same time, the rotary stirring powder spray desulfurization technology often has problems such as large heat loss of molten iron and large temperature drop of molten iron, as well as low carbon content in molten iron and low desulfurization efficiency; under some working conditions, there are also problems such as high dissolved oxygen in molten iron and large oxidation and burning loss of blown magnesium. Summary of the invention

[0004] In order to solve the problems existing in this technology, the main purpose of the present invention is to propose a multifunctional and efficient rotary stirring powder spraying desulfurization blowing method.

[0005] According to one aspect of the present invention, the present invention provides the following technical solution:

[0006] A multifunctional and efficient rotary stirring powder desulfurization blowing method is disclosed. Carbon powder is added to the existing rotary stirring powder desulfurization blowing desulfurization powder (passivated magnesium, lime or limestone) to increase the fluidity of the desulfurization powder and prevent the powder from clogging the blowing channel during the blowing process. At the same time, molten iron can be carbonized to achieve the powder carbonization function, increase the chemical latent heat of the molten iron, and increase the activity coefficient of sulfur in the molten iron to promote desulfurization; at the same time, hydrogen, natural gas, coke oven gas and other hydrogen-rich gases are used as carrier gases instead of nitrogen and argon for blowing. The blown hydrogen-rich gas can react with oxygen in the molten iron to reduce oxygen in the molten iron, promote desulfurization, and reduce the loss caused by the reaction of magnesium powder with oxygen in the molten iron; at the same time, the blown gas also directly reacts with sulfur in the molten iron to play a desulfurization role.

[0007] As a preferred embodiment of the multifunctional and efficient rotary stirring powder spray desulfurization method described in the present invention, the mass proportion of carbon powder in the spray powder is 5-80wt%, the average particle size of the carbon powder is 1-1000μm, the carbon content in the carbon powder is ≥90wt%, the loss on ignition is ≤3wt%, the carbon content in the molten iron after spraying is ≥3.0wt%. The average particle size of the spray powder is 1-1000μm.

[0008] As a preferred embodiment of the multifunctional and efficient rotary stirring powder spraying desulfurization blowing method described in the present invention, the pressure of the hydrogen-rich gas is 0.5-1.6MPa and the flow rate is 0.3-3.0Nm 3 / min.

[0009] As a preferred embodiment of the multifunctional and efficient rotary stirring powder spraying desulfurization blowing method described in the present invention, the powder spraying outlet is located at the lower part of the molten iron ladle, 200-600 mm away from the bottom of the molten iron ladle; while spraying powder, a stirring paddle is used to stir the molten iron, the position of the stirring paddle blades is slightly higher than the powder spraying outlet in the molten iron or at the same height as the powder spraying outlet, and the stirring paddle speed is ≥60r / min.

[0010] As a preferred embodiment of the multifunctional and efficient rotary stirring powder spray desulfurization method described in the present invention, the spraying speed of the spray powder into the molten iron during rotary stirring powder spray desulfurization is 0.1-2.0 kg / t 铁 ·min.

[0011] As a preferred embodiment of the multifunctional and efficient rotary stirring powder spraying desulfurization blowing method described in the present invention, the rotary stirring powder spraying desulfurization process is as follows:

[0012] In the first 2-5 minutes, carbon powder and lime or limestone are sprayed;

[0013] After 2-5 minutes of spraying, add magnesium powder, and spray carbon powder, magnesium powder and lime or limestone;

[0014] After spraying for 8-15 minutes, reduce the proportion of magnesium powder blown in.

[0015] The beneficial effects of the present invention are as follows:

[0016] The present invention proposes a preferred scheme for a multifunctional and efficient rotary stirring powder spraying desulfurization blowing method, which realizes the carbon enhancement function of the molten iron pretreatment process by adding carbon powder to the existing desulfurization powder, avoids the blockage of the powder channel, and promotes the desulfurization reaction; at the same time, hydrogen, natural gas, coke oven gas and other hydrogen-rich gases are used as carrier gases to remove the higher dissolved oxygen in the molten iron and participate in desulfurization, thereby realizing efficient desulfurization. DETAILED DESCRIPTION

[0017] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The present invention provides a multifunctional and efficient rotary stirring powder spray desulfurization blowing method, in which carbon powder is added to the spray desulfurization powder of the existing rotary stirring powder spray desulfurization to increase the fluidity of the desulfurization powder, improve the powder-to-gas ratio, and prevent the powder appearing in the spraying process from clogging the spraying channel. At the same time, the molten iron can be carbonized to achieve the powder spray carbonization function, increase the chemical latent heat of the molten iron, and increase the activity coefficient of sulfur in the molten iron to promote desulfurization; on the other hand, hydrogen, natural gas, coke oven gas and other hydrogen-rich gases are used as carrier gases instead of nitrogen and argon for spraying, and the hydrogen-rich gas blown in can react with oxygen in the molten iron, reduce oxygen in the molten iron, promote desulfurization, and reduce the loss caused by the reaction of magnesium powder with oxygen in the molten iron; at the same time, the blown gas also directly reacts with sulfur in the molten iron to play a desulfurization role.

[0019] Preferably, a mixture of desulfurization powder (passivated magnesium, lime or limestone) and carbon powder is used as the spray powder, the mass proportion of carbon powder in the spray powder is 5-80wt%, the particle size of the carbon powder is 1-1000μm, the carbon content in the carbon powder is ≥90wt%, the loss on ignition is ≤3wt%, and the carbon content in the molten iron after spraying is ≥3.0wt%. The average particle size of the spray powder is 1-1000μm.

[0020] Preferably, hydrogen, natural gas, coke oven gas or other hydrogen-rich gas is used as the carrier gas instead of nitrogen and argon for injection, with a gas pressure of 0.5-1.6 MPa and a gas flow rate of 0.3-3.0 Nm 3 / min; when the existing desulfurization powder is sprayed, the powder-gas ratio is 30-80kg / Nm 3 When the mixture of desulfurization powder and carbon powder is used as the spray powder, the powder-gas ratio increases with the increase of carbon content. When the carbon content reaches 70wt%, the powder-gas ratio is 60-200kg / Nm 3 .

[0021] Preferably, the powder spraying outlet is located at the lower part of the molten iron ladle, 200-600 mm away from the bottom of the ladle; while spraying powder, a stirring paddle is used to stir the molten iron, the position of the stirring paddle blade is slightly higher than the powder spraying outlet in the molten iron or at the same height as the powder spraying outlet, and the stirring paddle speed is ≥60 r / min; through stirring, the blown powder gas is dispersed into dispersed tiny powder bubbles, and the size of the generated powder bubbles is controlled to be 0.1-3.0 mm.

[0022] Preferably, during the rotary stirring powder spray desulfurization, the spray powder is sprayed into the molten iron at a rate of 0.1-2.0 kg / t 铁 ·min.

[0023] Preferably, during the rotary stirring powder spraying desulfurization, the powder sprayed into the molten iron can be adjusted during the spraying process. Specifically, the rotary stirring powder spraying desulfurization process is:

[0024] In the first 2-5 minutes, carbon powder and lime or limestone are sprayed to form a slag layer on the molten iron slag surface, which is beneficial to improve the recovery rate of magnesium and carbon powder, and can also suppress the initial splashing;

[0025] After 2-5 minutes of spraying, adding magnesium powder, spraying carbon powder, magnesium powder and lime or limestone can increase the desulfurization speed;

[0026] After spraying for 8-15 minutes, reducing the proportion of magnesium powder blown in will help improve the utilization rate of magnesium.

[0027] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0028] Example 1

[0029] A steel plant uses rotary stirring spraying method for desulfurization treatment. The molten iron in the ladle weighs 210 tons. The sulfur content and carbon content in the molten iron are 0.120wt% and 3.11wt% respectively. First, carbon powder and lime powder are sprayed for 3 minutes. The spraying carrier gas is hydrogen. The powder spraying speed is 240kg / min. The mass ratio of carbon powder in the powder is 50wt%, the average particle size of carbon powder is 800μm, the carbon content in carbon powder is 97wt%, the ignition loss ratio is 1.0wt%, the average particle size of lime powder is 1000μm, the hydrogen pressure is 1.1MPa, and the flow rate is 1.2Nm 3 / min, powder-gas ratio is 200kg / Nm 3 After 3 minutes of spraying, magnesium powder was added to the powder. The average particle size of the magnesium powder was 1000 μm. The mass ratio of magnesium powder, carbon powder and lime powder in the powder was 2.5:1:6.5. The hydrogen pressure and flow rate were 1.3 MPa and 1.0 Nm 3 / min, powder-gas ratio is 60kg / Nm 3 The powder spraying speed is 60kg / min, and the spraying time is 10min. The mass ratio of magnesium powder, carbon powder and lime powder in the powder is adjusted to 1:2:7, and the spraying time is continued for 10min. The sulfur content and carbon content in the molten iron are changed to 0.002wt% and 3.22wt% respectively.

[0030] Example 2

[0031] A steel plant uses rotary stirring spraying method for desulfurization treatment. The molten iron in the ladle weighs 210 tons. The sulfur content and carbon content in the molten iron are 0.13wt% and 3.32wt% respectively. First, carbon powder and lime powder are sprayed for 3 minutes. The spraying carrier gas is natural gas. The powder spraying speed is 360kg / min. The mass ratio of carbon powder in the powder is 80wt%. The average particle size of carbon powder is 500μm. The carbon content in carbon powder is 96wt%, the loss on ignition ratio is 1.2wt%, the average particle size of lime powder is 1000μm, the pressure of natural gas is 1.2MPa, and the flow rate is 2.0Nm3 / min, powder-gas ratio is 180kg / Nm 3 After 3 minutes of spraying, magnesium powder was added to the powder. The average particle size of the magnesium powder was 1000 μm. The mass ratio of magnesium powder, carbon powder and lime powder in the powder was 2.5:1:6.5. The natural gas pressure and flow rate were 1.2 MPa and 1.0 Nm 3 / min, powder-gas ratio is 60kg / Nm 3 The powder spraying speed is 60kg / min, and the spraying time is 10min. The mass ratio of magnesium powder, carbon powder and lime powder in the powder is adjusted to 1:2:7, and the spraying time is continued for 10min. The sulfur content and carbon content in the molten iron are changed to 0.002wt% and 3.72wt% respectively.

[0032] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A multifunctional and efficient rotary stirring powder spraying desulfurization blowing method, characterized in that: A mixture of desulfurization powder and carbon powder is used as the spraying powder, and hydrogen-rich gas is used as the carrier gas to realize the spraying of the spraying powder.

2. The multifunctional and efficient rotary stirring powder spraying desulfurization blowing method according to claim 1 is characterized in that: The desulfurization powder is passivated magnesium, lime or limestone; the hydrogen-rich gas is hydrogen, natural gas or coke oven gas.

3. The multifunctional and efficient rotary stirring powder spraying desulfurization blowing method according to claim 1 is characterized in that: The mass proportion of carbon powder in the spraying powder is 5-80wt%, the average particle size of the carbon powder is 1-1000μm, the carbon content in the carbon powder is ≥90wt%, the loss on ignition is ≤3wt%, and the carbon content in the molten iron after spraying is ≥3.0wt%.

4. The multifunctional and efficient rotary stirring powder spraying desulfurization blowing method according to claim 1 is characterized in that: The pressure of hydrogen-rich gas is 0.5-1.6MPa and the flow rate is 0.3-3.0Nm 3 / min.

5. The multifunctional and efficient rotary stirring powder spraying desulfurization blowing method according to claim 1 is characterized in that: The powder spraying outlet is located at the lower part of the ladle, 200-600mm away from the bottom of the ladle; while spraying powder, a stirring paddle is used to stir the molten iron, the position of the stirring paddle blade is slightly higher than the powder spraying outlet in the molten iron or at the same height as the powder spraying outlet, and the stirring paddle speed is ≥60r / min.

6. The multifunctional and efficient rotary stirring powder spraying desulfurization blowing method according to claim 1 is characterized in that: During the rotary stirring powder spray desulfurization, the spray powder sprayed into the molten iron is injected at a rate of 0.1-2.0kg / t 铁 ·min.

7. The multifunctional and efficient rotary stirring powder spraying desulfurization blowing method according to claim 1 is characterized in that: The rotary stirring powder spraying desulfurization process is: In the first 2-5 minutes, carbon powder and lime or limestone are sprayed; After 2-5 minutes of spraying, add magnesium powder, and spray carbon powder, magnesium powder and lime or limestone; After spraying for 8-15 minutes, reduce the proportion of magnesium powder blown in.