A low-cost, high-efficiency method for molten iron slag removal

Abstract

The present invention provides a low-cost, high-efficiency molten iron slag skimming method, comprising the following steps: 1) processing steelmaking dust, magnetic separation slag powder, and refining tailings into a slag conditioning agent in a certain proportion; 2) rapidly stirring the molten iron upon arrival at the station to thoroughly mix the blast furnace slag and the molten iron insulation agent, utilizing the heat of the molten iron to melt small iron beads that have solidified or crusted in the slag, and simultaneously utilizing the centrifugal force of the stirring to separate the slag from the iron; 3) measuring the slag thickness and determining the amount of slag conditioning agent to be added based on the slag thickness; 4) adding the conditioning agent and stirring, and measuring the temperature after stirring is completed; 5) lowering an air blast slag removal gun, with the gun tip at a certain distance from the molten iron surface, cooling the gun according to the molten iron temperature, controlling the gas flow, and closing the cooling air after cooling until the slag surface is slightly crusted, and raising the gun; 6) tilting the molten iron ladle for slag skimming. This slag skimming method reduces KR skimming iron loss, shortens KR skimming time, and improves skimming efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, and in particular to a low-cost and high-efficiency molten iron skimming method. Background Art

[0002] During the blast furnace tapping process, slag and iron are primarily separated by skimmers, so a certain amount of slag is inevitably carried over into the molten iron, typically at a rate of 6‰. After tapping, an insulator is added to the molten iron surface to maintain heat, at an average rate of 1kg / ton per ton of iron, for a total of 7kg / ton. Blast furnace slag is high in sulfur and titanium, with a sulfur content of approximately 1% and a TiO2 content of 2%. Directly feeding this slag into the converter (BOF) increases sulfur in the molten steel, deteriorating the converter's operating environment. Furthermore, blast furnace slag has a low basicity of 1.1-1.4, while the insulator is primarily composed of carbonized rice husks, primarily SiO2. This material, when introduced into the BOF, reduces the converter's basicity, increases the slag volume, and compromises dephosphorization efficiency. Therefore, reducing the amount of slag carried over into the BOF is a key approach to improving the converter's technical and economic performance.

[0003] When producing ultra-low sulfur steel, the molten iron needs to be desulfurized again. The molten iron slag is acidic slag, which seriously affects the desulfurization effect. Therefore, it is generally necessary to skim the molten iron before the desulfurization operation to improve the desulfurization effect and reduce the cost of the desulfurizer.

[0004] In summary, whether based on cost or quality considerations, molten iron slag removal is required. However, during the slag removal process, due to poor slag-iron separation and the high fluidity of the molten iron slag, the molten iron slag will flow away from both sides of the slag removal plate, resulting in poor slag removal effect, high iron content, and iron loss exceeding 4kg / t. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a low-cost, high-efficiency molten iron slag stripping method, which reduces KR slag stripping iron loss, shortens KR slag stripping time, improves slag stripping effect, reduces the amount of slag in molten iron, reduces the consumption of auxiliary materials such as converter lime, and realizes low-slag smelting.

[0006] In order to achieve the above object, the present invention provides a method for skimming molten iron with low cost and high efficiency, comprising the following steps:

[0007] 1) Process steelmaking dust, magnetic separation slag powder and refining tailings into slag conditioning agent according to a certain proportion;

[0008] 2) When the molten iron arrives at the station, it is quickly stirred to fully mix the blast furnace slag and the molten iron insulation. The heat of the molten iron is used to melt the small iron beads that have solidified or crusted in the slag. At the same time, the centrifugal force of the stirring is used to separate the slag from the iron.

[0009] 3) Measure the slag thickness and determine the amount of slag conditioning agent to be added based on the slag thickness;

[0010] 4) Add the test agent and stir, and measure the temperature after stirring;

[0011] 5) Lower the air-blowing slag-removing gun, with the gun tip at a certain distance from the molten iron surface. Cool the molten iron according to its temperature, control the gas flow, and turn off the cooling gas after the slag surface is slightly crusted. Raise the gun;

[0012] 6) The molten iron ladle is tilted and the slag is removed.

[0013] Wherein, in the step 1), steelmaking dust, magnetic separation slag powder and refining tailings and other materials are processed into slag conditioning agent with a particle size of 10-20 mm according to a certain proportion.

[0014] Wherein, in said step 2), the molten iron is rapidly stirred for 3-5 minutes upon arrival at the station, with a rotation speed of ≥90r / min.

[0015] In the step 2), the fluffy heat-insulating agent is gradually melted into liquid, and the non-uniform slag is further transformed into uniform slag, thereby reducing the slag viscosity and improving the fluidity of the molten iron front slag.

[0016] Wherein, the amount of the modifier added in step 3) is determined according to the amount of slag in the molten iron and the temperature of the molten iron.

[0017] Wherein, in the step 4), after adding the slag regulating agent, stirring is carried out for 10-15 minutes, and the rotation speed is controlled at 80-100 r / min.

[0018] Wherein, in the step 5), the air blowing slag driving gun is lowered, the gun head is 2m away from the molten iron surface, and the molten iron temperature is cooled for 30-90s, and the gas flow rate is controlled at 120NM3 / h.

[0019] Compared with the prior art, the advantages and positive effects of the present invention are: the low-cost, high-efficiency molten iron slag stripping method provided by the present invention reduces KR slag stripping iron loss; shortens the KR slag stripping time and improves the KR slag stripping effect; reduces the amount of slag carried by molten iron, reduces the consumption of auxiliary materials such as converter lime, and realizes low-slag smelting. DETAILED DESCRIPTION

[0020] The present invention is described in detail below by way of exemplary embodiments. However, it should be understood that structures and features in one embodiment may be beneficially combined in other embodiments without further description.

[0021] The present invention provides an embodiment of the present invention. 1. A low-cost, high-efficiency molten iron skimming method, characterized in that it includes the following steps:

[0022] 1) Process steelmaking dust, magnetic separation slag powder and refining tailings into slag conditioning agent according to a certain proportion;

[0023] 2) When the molten iron arrives at the station, it is quickly stirred to fully mix the blast furnace slag and the molten iron insulation. The heat of the molten iron is used to melt the small iron beads that have solidified or crusted in the slag. At the same time, the centrifugal force of the stirring is used to separate the slag from the iron.

[0024] 3) Measure the slag thickness and determine the amount of slag conditioning agent to be added based on the slag thickness;

[0025] 4) Add the test agent and stir, and measure the temperature after stirring;

[0026] 5) Lower the air-blowing slag-removing gun, with the gun tip at a certain distance from the molten iron surface. Cool the molten iron according to its temperature, control the gas flow, and turn off the cooling gas after the slag surface is slightly crusted. Raise the gun;

[0027] 6) The molten iron ladle is tilted and the slag is removed.

[0028] In the step 1), the steelmaking dust, magnetic separation slag powder and refining tailings are processed into a slag conditioning agent with a particle size of 10-20 mm according to a certain proportion, and the final synthetic slag composition is:

[0029] Too bad Easy FeO <![CDATA[SiO2]]> CaO MgO <![CDATA[Al2O3]]> 10-30 10-20 10-20 ≤8 ≥40 5-10 10-30

[0030] Wherein, in said step 2), the molten iron is rapidly stirred for 3-5 minutes upon arrival at the station, with a rotation speed of ≥90r / min.

[0031] In the step 2), the fluffy heat-insulating agent is gradually melted into liquid, and the non-uniform slag is further transformed into uniform slag, thereby reducing the slag viscosity and improving the fluidity of the molten iron front slag.

[0032] Wherein, the amount of the modifier added in step 3) is determined according to the amount of slag in the molten iron and the temperature of the molten iron.

[0033] Wherein, in the step 4), after adding the slag regulating agent, stirring is carried out for 10-15 minutes, and the rotation speed is controlled at 80-100 r / min.

[0034] Wherein, in the step 5), the air blowing slag driving gun is lowered, the gun head is 2m away from the molten iron surface, and the molten iron temperature is cooled for 30-90s, and the gas flow rate is controlled at 120NM3 / h.

[0035] Specifically, the present invention is based on the premise of 120t hot metal ladle slag removal as an example:

[0036] Example 1

[0037] When the molten iron ladle arrives at the station, slag samples are taken for testing and stirred for 3 minutes. The TFe content in the slag is 30%;

[0038] After stirring, the slag thickness is measured to be 10 cm (7 kg / t of iron strip slag), and 0.8 t of slag conditioning agent is added;

[0039] After stirring for 12 minutes, the mixture was cooled with air for 30 seconds and then slag was removed. The slag sample was tested and the TFe content in the slag was 3.0%.

[0040] Example 2

[0041] When the molten iron ladle arrives at the station, slag samples are taken for testing and stirred for 3 minutes. The TFe content in the slag is 40%;

[0042] After stirring, the slag thickness is measured to be 8cm (5.6kg / t of iron slag), and 0.6t of slag conditioning agent is added;

[0043] After stirring for 10 minutes and cooling with air for 45 seconds, the slag was skimmed off and the slag sample was tested. The TFe content in the slag was 3.5%.

[0044] Furthermore, in order to better compare the technology of the present invention with the prior art, the present invention conducted a comparative test:

[0045] Compare and skim off slag of the same thickness of hot metal slag, and make sure the skimming effect reaches a uniform standard (hot metal exposed area ≥ 90%). Compare the skimming iron loss by weighing with an overhead crane.

[0046]

[0047] The above results show that the comparative example achieves the same slag removal effect, but loses 0.47t less than the embodiment, and the iron loss per ton of iron is reduced by 3.93kg / t.

[0048] In summary, the low-cost, high-efficiency molten iron slag stripping method provided by the present invention reduces KR slag stripping iron loss; shortens KR slag stripping time and improves KR slag stripping effect; reduces the amount of slag in molten iron, reduces the consumption of auxiliary materials such as converter lime, and realizes low-slag smelting. In the embodiment of the present invention, the slag stripping iron loss per ton of iron is reduced by 3.93 kg, and the molten iron price is calculated at 3,000 yuan, so the cost per ton of iron is reduced by 11.79 yuan / t. The slag stripping method provided by the present invention also achieves the technical effect of reducing costs.

[0049] Although the present invention has been described in detail by way of preferred embodiments, the invention is not limited thereto. The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to be embodied in the widest possible manner consistent with the principles and novel features disclosed herein.

Claims

1. A low-cost, high-efficiency molten iron skimming method, characterized by: The steps include: 1) Processing steelmaking dust, magnetic separation slag powder and refining tailings into slag conditioning agent according to a certain proportion; The composition of slag conditioning agent is: TFe 10-30, MFe 10-20, FeO 10-20, SiO2≤8, CaO≥40, MgO 5-10, Al2O310-30; 2) When the molten iron arrives at the station, it is quickly stirred to fully mix the blast furnace slag and the molten iron insulation. The heat of the molten iron is used to melt the small iron beads that have solidified or crusted in the slag. At the same time, the centrifugal force of the stirring is used to separate the slag from the iron. 3) Measure the slag thickness and determine the amount of slag conditioning agent to be added based on the slag thickness; 4) Add the investigation agent and stir, then measure the temperature after stirring; 5) Lower the air-blowing slag-removing gun, with the gun tip at a certain distance from the molten iron surface. Cool the molten iron according to its temperature, control the gas flow, and turn off the cooling gas after the slag surface is slightly crusted. Raise the gun; 6) The molten iron ladle is tilted and the slag is removed.

2. The low-cost, high-efficiency molten iron skimming method according to claim 1, characterized in that: In the step 1), steelmaking dust, magnetic separation slag powder and refining tailings are processed in a certain proportion to form a slag conditioning agent with a particle size of 10-20 mm.

3. The low-cost, high-efficiency molten iron skimming method according to claim 1, characterized in that: In the step 2), the molten iron is rapidly stirred for 3-5 minutes at a rotation speed of ≥90 r / min upon arrival at the station.

4. The low-cost, high-efficiency molten iron skimming method according to claim 1, characterized in that: In the step 2), the fluffy heat-insulating agent is further gradually melted into a liquid state, and the non-uniform slag is further transformed into a uniform slag, thereby reducing the slag viscosity and improving the fluidity of the molten iron front slag.

5. The low-cost, high-efficiency molten iron skimming method according to claim 1, characterized in that: The amount of slag conditioning agent added in step 3) is determined according to the amount of slag in the molten iron and the temperature of the molten iron.

6. The low-cost, high-efficiency molten iron skimming method according to claim 1, characterized in that: After adding the slag conditioning agent in step 4), stir for 10-15 minutes, and control the rotation speed at 80-100 r / min.

7. The low-cost, high-efficiency molten iron skimming method according to claim 1, characterized in that: In step 5), the air-blowing slag-removing gun is lowered, the gun head is 2m away from the molten iron surface, and the molten iron temperature is cooled for 30-90s, and the gas flow rate is controlled at 120Nm 3 / h.

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