CN110578030A

CN110578030A - Desulfurization method of low-phosphorus low-silicon molten iron

Info

Publication number: CN110578030A
Application number: CN201910809543.0A
Authority: CN
Inventors: 刘志国; 张志祥; 徐涛; 张勇; 周海川; 卜二军
Original assignee: Inner Mongolia Saisipu Technology Co Ltd
Current assignee: Inner Mongolia Saisipu Technology Co Ltd
Priority date: 2019-08-29
Filing date: 2019-08-29
Publication date: 2019-12-17

Abstract

The application relates to a desulfurization method of low-phosphorus low-silicon molten iron, which comprises the following steps that after tapping is finished, a ladle car is driven to a wire feeding position, the temperature is controlled at 1450-. The method has better desulfurization effect, and the desulfurization rate can reach more than 92%.

Description

Desulfurization method of low-phosphorus low-silicon molten iron

Technical Field

The invention relates to the field of ferrous metallurgy, in particular to a high-efficiency low-phosphorus low-silicon molten iron wire feeding molten iron desulphurization method.

Background

In the production of molten reduced iron, the initial molten iron contains up to 0.06% of sulfur, phosphorus: 0.025-0.035%, silicon: 0.15-0.25%, ordinary blast furnace molten iron phosphorus (0.10-0.25%) is lower than silicon content (0.35-0.65%), and ironWater cannot be used directly for steel making or casting. The low phosphorus and low silicon also cause difficult slagging and high difficulty of desulfurization. In order to reduce the desulfurization cost and improve the operation efficiency, a simple and efficient molten iron desulfurization device is needed to perform desulfurization treatment on molten iron. Adding soda ash (Na) during tapping₂CO₃) Or KR method is adopted, but because a large amount of white smoke and Na slag are generated in the production process, the environment is polluted; mg particles are added into molten iron by adopting a spraying method, the Mg segregation phenomenon exists, the stable supply to the molten iron can not be realized, and the investment cost is relatively high; therefore, the simple and efficient low-phosphorus low-silicon molten iron desulfurization method is invented by researching the technical parameters of the feeding speed of the passivated magnesium cored wire, the desulfurization speed, nitrogen blowing at the bottom of the ladle and the like.

Disclosure of Invention

In order to solve the technical problems, the invention provides a high-efficiency low-phosphorus low-silicon molten iron desulphurization method, which can solve the problems of high sulfur content, difficult desulphurization slag removal, environmental pollution and low desulphurization rate of the low-phosphorus low-silicon molten iron and provide high-quality molten iron for subsequent steelmaking or casting.

The specific technical scheme provided by one embodiment of the application is as follows:

A low-phosphorus low-silicon molten iron desulphurization method comprises the following steps that after tapping is finished, a ladle car is driven to a wire feeding position, the temperature is controlled at 1450-.

Further, the low-phosphorus and low-silicon molten iron comprises the following components: c: 3.6 to 4.5 percent of Mn, less than or equal to 0.1 percent of Mn, 0.08 to 0.15 percent of S, P: 0.020-0.060%, Si: 0.01-0.10 percent.

Further, after tapping, the liquid level of the ladle is controlled to be 300-500 mm of clearance above the refractory material.

Further, the heat preservation agent is carbonized rice hulls.

Further, the heat preservation agent comprises the following components in percentage by mass: 5-15% of coke powder; fly ash: 10 to 15 percent; sintered dolomite 2-4%; 3-7% of expanded vermiculite; 5-8% of carboxymethyl cellulose, not more than 0.010% of S, not more than 0.010% of P, and the balance of carbonized rice hulls and inevitable impurities.

further, the passivated magnesium cored wire is wrapped by an iron sheet, the diameter of the cored wire is 10-15mm, the thickness of the iron sheet is 0.1-0.4mm, the core is a desulfurizer, and the desulfurizer comprises, by mass, 30-50% of passivated magnesium, 10-15% of calcium oxide, 15-20% of fluorite, 5-10% of barium oxide, 8-15% of silicon dioxide, 3-8% of calcium carbide, and 4-10% of aluminum oxide, wherein the sum of the compositions is 100%.

Further, the nitrogen flow rate before and after feeding was 80NL/min, and the lime particles were added in an amount of 2 kg/t.

Furthermore, the desulfurized molten iron is subjected to slag skimming in time, the slag alkalinity is controlled to be 2.5-3.0, and the sulfur content of the desulfurized molten iron is lower than 0.01%.

Furthermore, the mass fraction of sulfur after desulfurization is more than 1.8%, the sulfur capacity is higher, and the subsequent resulfurization is avoided.

According to the desulfurization method for the low-phosphorus and low-silicon molten iron, the desulfurization efficiency is improved by optimizing the technical parameters such as the material quality of the passivated magnesium core-spun yarn, the feeding speed, the desulfurization rate, the inert gas blown from the bottom of the iron ladle and the like, the method is particularly effective for molten iron produced by smelting reduction, and meanwhile, the components of the heat insulating agent and the core-spun yarn are optimized, so that the desulfurization effect is better, and the desulfurization rate can reach more than 85%.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention are clearly and completely described below. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.

The technical solution of the present invention will be further explained and illustrated with reference to the following specific examples.

Example 1

When the test is carried out on molten iron produced by certain smelting reduction ironmaking, the initial molten iron comprises the following components: 4.2%, Mn: 0.08%, S: 0.1%, P: 0.045%, Si: 0.05 percent. And (2) desulfurizing, which comprises the following steps that after tapping is finished, the liquid level of a ladle is controlled to be 450mm above refractory along a clearance, a ladle car is driven to a wire feeding position, the temperature is controlled to be 1500 ℃, bottom blowing nitrogen is connected, the nitrogen flow is 70NL/min, lime particles are added from the liquid level of the molten iron, the adding amount is 3kg/t of molten iron, a ladle bottom blowing nitrogen system is closed after lime is melted, a heat preservation agent is added, the heat preservation agent is carbonized rice hulls, then passivated magnesium core-spun yarns are fed at the wire feeding speed of 40m/min, the wire feeding amount is 0.5kg/t of iron, wire feeding needs to be finished once wire feeding, the ladle bottom blowing nitrogen system is started after the wire feeding is finished, the bottom blowing flow is 70NL/min, and bottom blowing is stopped for 4 min. The passivated magnesium cored wire is wrapped by an iron sheet, the diameter of the cored wire is 12mm, the thickness of the iron sheet is 0.3mm, the core is a desulfurizer, and the desulfurizer comprises 45% of passivated magnesium, 12% of calcium oxide, 13% of fluorite, 8% of barium oxide, 10% of silicon dioxide, 4% of calcium carbide and 8% of aluminum oxide by mass%. And the desulfurized molten iron is subjected to slag skimming in time, the slag alkalinity is controlled to be 2.7, and the sulfur content of the desulfurized molten iron is lower than 0.008 percent. The desulfurization rate is as high as 92 percent.

Example 2

When the test is carried out on molten iron produced by certain smelting reduction ironmaking, the initial molten iron comprises the following components: 4.1%, Mn: 0.07%, S: 0.12%, P: 0.03%, Si: 0.07 percent. And (2) carrying out desulfurization, comprising the following steps of controlling the liquid level of the ladle to the upper edge clearance of refractory material by 400mm after tapping is finished, driving the ladle car to a feeding line position, controlling the temperature at 1450 ℃, switching on bottom blowing nitrogen, wherein the nitrogen flow is 80NL/min, adding lime particles from the liquid level of the molten iron, the adding amount is 3.5kg/t of molten iron, closing a ladle bottom blowing nitrogen system after lime is melted, and adding a heat preservation agent, wherein the heat preservation agent comprises the following components in percentage by mass: 12% of coke powder; fly ash: 11 percent; 3% of sintered dolomite; 4% of expanded vermiculite; 6% of carboxymethyl cellulose, not more than 0.010% of S, not more than 0.010% of P, and the balance of carbonized rice hulls and inevitable impurities. Then feeding the passivated magnesium core-spun yarn at a yarn feeding speed of 35m/min, wherein the yarn feeding amount is 0.6kg/t iron, the yarn feeding needs to be finished once, a bottom nitrogen blowing system of the iron ladle is started after the yarn feeding is finished, the bottom blowing flow is 80NL/min, and the bottom blowing is stopped for 3 min. The passivated magnesium cored wire is wrapped by an iron sheet, the diameter of the cored wire is 10mm, the thickness of the iron sheet is 0.3mm, the core is a desulfurizer, the composition of the desulfurizer comprises 38% of passivated magnesium, 15% of calcium oxide, 18% of fluorite, 7% of barium oxide, 10% of silicon dioxide and 4% of calcium carbide by mass percent, 8% of aluminum oxide, molten iron after desulfurization is subjected to slag removal in time, the alkalinity of slag is controlled to be 2.8, and the sulfur content of the molten iron after desulfurization is lower than 0.008%. The desulfurization rate is as high as 93.3 percent.

Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A low-phosphorus low-silicon molten iron desulphurization method is characterized by comprising the following steps that after tapping is finished, a ladle car is driven to a wire feeding position, the temperature is controlled at 1450-.

2. The method of claim 1, wherein the low-phosphorous low-silicon molten iron comprises the following components: c: 3.6 to 4.5 percent of Mn, less than or equal to 0.1 percent of Mn, 0.08 to 0.15 percent of S, P: 0.020-0.060%, Si: 0.01-0.10 percent.

3. The method for desulfurizing a low-phosphorus and low-silicon molten iron as claimed in claim 1 to 2, wherein a clearance between a liquid level of the ladle and a refractory upper edge is controlled to be 300mm to 500mm after tapping.

4. The method for desulfurizing a low-phosphorus, low-silicon molten iron according to claims 1 to 3, wherein the insulating agent is carbonized rice husk.

5. The method for desulfurizing the molten iron with low phosphorus and low silicon content according to claims 1 to 3, wherein the heat retaining agent comprises the following components in parts by mass: 5-15% of coke powder; fly ash: 10 to 15 percent; sintered dolomite 2-4%; 3-7% of expanded vermiculite; 5-8% of carboxymethyl cellulose, not more than 0.010% of S, not more than 0.010% of P, and the balance of carbonized rice hulls and inevitable impurities.

6. The method for desulfurizing a low-phosphorus and low-silicon molten iron according to claims 1 to 5, wherein the passivated magnesium cored wire is wrapped by an iron sheet, the diameter of the cored wire is 10 to 15mm, the thickness of the iron sheet is 0.1 to 0.4mm, the core is a desulfurizing agent, the desulfurizing agent comprises 30 to 50% by mass of passivated magnesium, 10 to 15% by mass of calcium oxide, 15 to 20% by mass of fluorite, 5 to 10% by mass of barium oxide, 8 to 15% by mass of silicon dioxide, 3 to 8% by mass of calcium carbide and 4 to 10% by mass of aluminum oxide, and the sum of the above compositions is 100%.

7. The method for desulfurizing molten iron having low phosphorus and low silicon content according to claims 1 to 6, wherein the flow rate of nitrogen before and after feeding is 80NL/min, and the amount of lime particles added is 2 kg/t.

8. The method for desulfurizing a low-phosphorus and low-silicon molten iron according to claim 1 to 7, wherein the desulfurized molten iron is subjected to slag skimming in time, the basicity of the slag is controlled to be 2.5 to 3.0, and the sulfur content of the desulfurized molten iron is less than 0.01%.

9. The method for desulfurizing a low-phosphorus, low-silicon molten iron according to any one of claims 1 to 8, wherein the mass fraction of sulfur after desulfurization is greater than 1.8%, the sulfur capacity is high, and subsequent resulfurization is avoided.