Semi-steel steelmaking method for smelting SPA-H weathering resistant steel at low cost

Abstract

The invention provides a semi-steel steelmaking method for smelting SPA-H weathering resistant steel at low cost, the purpose of producing the SPA-H weathering resistant steel at low cost is achieved by developing a scrap steel structure and adjusting the corresponding converter steelmaking gun position, flow and the like in a matched mode, and the method comprises the following steps that scrap steel is directly added into a converter through a hopper before iron is added into the converter; after vanadium extraction semisteel is added into the converter, oxygen blowing is started, magnesium slag charge is added for slagging in the oxygen blowing process, converter dephosphorization is controlled by changing the lance position of an oxygen lance, the oxygen supply strength and the slag charge adding time, converter decarbonization is completed, and qualified molten steel is obtained. The method provided by the invention realizes cyclic utilization of the converter steel slag, is beneficial to reducing the amount of steel slag generated in the smelting process of weathering steel, reducing metal iron loss caused by iron elements in steel entering the slag, reducing the consumption of slag making materials in the smelting process, achieving the purpose of saving the production cost, reducing the emission of converter wastes, and being beneficial to environmental protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of steel metallurgy, in particular to a semi-steel smelting method for low-cost smelting SPA-H weathering steel. BACKGROUND

[0002] The semi-steel is an intermediate product formed after the vanadium extraction process of molten iron in a converter, and compared with the molten iron, the silicon, manganese, carbon and other elements in the semi-steel are partially oxidized in the vanadium extraction process. The semi-steel smelting process has the characteristics of insufficient heat and single slag system, which causes the problems of difficult slagging in the production process, difficult dephosphorization, high content of iron oxide in the slag and the like. The converter steel slag in the traditional process is generally used for pollutant treatment, agricultural fertilizer, mineral filler and the like, and the iron element in the steel slag is not fully utilized, resulting in resource waste. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a semi-steel smelting method for low-cost smelting SPA-H weathering steel, so that the iron element in the steel slag is fully utilized and resource waste is avoided.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is as follows: A semi-steel smelting method for low-cost smelting SPA-H weathering steel, comprising the following steps: The scrap steel is directly added into the converter through a hopper before the converter is charged with iron; after the semi-steel for vanadium extraction is charged into the converter, oxygen blowing is started, and magnesium slag is added for slagging during the oxygen blowing process. The dephosphorization of the converter is controlled by changing the oxygen lance position, oxygen supply intensity and slag adding time, and the de-carbonization of the converter is completed to obtain qualified molten steel.

[0005] Preferably, the scrap steel includes roller-crushed and dried converter steel slag, SPA-H weathering steel slab head and tail, copper plate or other copper-containing alloy.

[0006] Preferably, the mass content of each component in the scrap steel is as follows: 28%-36% of the converter steel slag, 64%-72% of the SPA-H weathering steel slab head and tail, and the copper plate or other copper-containing alloy is calculated according to the steel grade requirement and copper content. The roller-crushed and dried converter steel slag is treated by roller crushing to meet the index of <30cm in maximum diameter, and the composition and mass content meet the following requirements: CaO%>30%, SiO2%<10%, MgO%>5%, P%<8%, S%<1%.

[0007] Preferably, the magnesium slag includes dolomite and light-burned dolomite, the mass content of MgO in the light-burned dolomite is 35-45%, and the mass content of MgO in the dolomite is 25-35%. The magnesium slag is added according to the equivalent replacement of MgO content. If the light-burned dolomite is used alone, the addition amount is 8-11kg / ton of steel, and if the dolomite is used alone, the addition amount is 11-15kg / ton of steel.

[0008] Preferably, the magnesia slag is added in two batches, the first batch is added at the beginning of the blowing oxygen step to 30%-40%, the amount is 60%-80% of the total mass; the second batch is added at the beginning of the blowing oxygen step to 60%-80%, the amount is 20%-40% of the total mass.

[0009] Preferably, the oxygen lance position is controlled in a high-low-low mode, the lance position is 1.8-1.85m in the early stage of the oxygen blowing process, the lance position is 1.7-1.75m in the middle stage of the oxygen blowing process, and the lance position is 1.55-1.6m in the late stage of the oxygen blowing process.

[0010] Preferably, the oxygen pressure in the oxygen blowing process is 0.70-0.85Mpa, and the oxygen supply intensity is 2.9-3.6 Nm 3 / (t·min), and the end temperature is 1630-1650℃.

[0011] Preferably, the semi-steel composition and mass content are: C: 2.5-3.5%, Si: 0.005-0.02%, Ti: 0.004-0.02%, Mn: 0.005-0.03%, and the balance is iron and other unavoidable elements.

[0012] Preferably, the qualified molten steel composition and mass content are: C: 0.07-0.10%, P: 0.07-0.10%, Cu: 0.25-0.35%, and the balance is iron and other unavoidable elements.

[0013] The beneficial effects produced by the above technical scheme are: The present application realizes the recycling of part of the converter steel slag, effectively reduces the slagging material consumption in the SPA-H weathering steel blowing process, and reduces the production of converter steel slag and the loss of metallic iron. DETAILED DESCRIPTION

[0014] The present application will be further described in detail in combination with specific embodiments.

[0015] The semi-steel steelmaking method for low-cost smelting SPA-H weathering steel of the present application is mainly aimed at scrap steel ratio and converter oxygen blowing, and the composition and percentage content of the semi-steel loaded into the converter are: C: 2.5-3.5%, Si: 0.005-0.02%, Ti: 0.004-0.02%, Mn: 0.005-0.03%, and the balance is iron and other unavoidable elements.

[0016] The composition and percentage content of the qualified molten steel are: C: 0.07-0.10%, P: 0.07-0.10%, Cu: 0.25-0.35%, and the balance is iron and other unavoidable elements.

[0017] The specific implementation method of each step is as follows: Scrap ratio step: The scrap structure is 28%-36% of converter steel slag, 64%-72% of SPA-H weathering steel slab cut-off tail, copper plate or other copper-containing alloy calculated according to the requirements of steel grade and copper content, and other scrap according to demand. The example uses a 150T converter, and the scrap loading amount per ton of steel is 40-70kg. The scrap is loaded into the converter through the converter port before the semi-steel is loaded into the converter. The scrap needs to be observed before being loaded into the converter. The maximum diameter of the steel slag should be less than 30cm, and it should be in an absolutely dry state. After the scrap is loaded into the converter, the converter is turned to 0 degrees to disperse the scrap in the converter and prevent the copper plate from adhering to the surface of the furnace lining at the furnace body, causing abnormal composition of the molten steel. The composition of the converter steel slag used in this method meets the following requirements: CaO%>30%, SiO2%<10%, MgO%>5%, P%<8%, and S%<1%.

[0018] Converter steelmaking step: After the scrap is loaded, the semi-steel is loaded into the converter. The semi-steel loading amount of the 150T converter is controlled at 170±5T, and the semi-steel loading angle of the converter is >55 degrees. Top blowing oxygen is used throughout the oxygen blowing process, assisted by bottom blowing argon stirring. The oxygen lance position is controlled at 1.8-1.85m before blowing oxygen, the bottom blowing argon flow is controlled at 400Nm 3 / h, the oxygen lance position is controlled at 1.7-1.75m during the middle stage of oxygen blowing, and the bottom blowing argon flow is controlled at 350Nm 3 / h, the oxygen lance position is controlled at 1.55-1.60m in the later stage of oxygen blowing, and the bottom blowing argon flow is controlled at 400Nm 3 / h, and the up and down adjustment range of the oxygen lance is <0.2m / time.

[0019] Magnesium slag is used as the slag material during the oxygen blowing process. For example, 8-11kg of light-burned dolomite is added per ton of steel (other magnesium materials are converted according to the percentage of MgO). The magnesium slag is added in two batches. The first batch is added at the beginning of the 30%-40% blowing step, and the amount is 60%-80% of the total. The second batch is added at the beginning of the 60%-80% blowing step, and the amount is 20%-40% of the total. No material is added 1-2min before the end of the oxygen blowing process until the end of the oxygen blowing process. The oxygen pressure during the oxygen blowing process is controlled at 0.70-0.85Mpa, the oxygen supply intensity is 2.9-3.6 Nm 3 / (t﹒min), the oxygen supply time is 10-12min, and the final temperature of the molten steel is 1630-1650℃. The ladle clearance is reserved at 500-600mm during the tapping process, and the bottom blowing argon stirring is used in the whole process of the ladle. The SPA-H weathering steel alloy is added during the tapping process, and the slide is used before the end of the tapping to assist in the detection of the infrared slag to block the slag. The converter is shaken to complete the operation of the furnace. Example 1

[0020] A steel plant 150t converter, semi-steel loading capacity of 167t, the composition of the semi-steel used is: C:3.1%, Si:0.008%, Ti:0.005%, Mn:0.015%, P:0.110%, S:0.076%.

[0021] Converter slag addition amount is 22kg / t, the total amount of scrap steel accounts for 35%, SPA-H slab addition amount is 40kg / t, the total amount of scrap steel accounts for 65%, the composition of the converter slag used is: CaO%:32%, SiO2%:6.5%, MgO%:6.2%, P%:5.1%, S%:0.35%.

[0022] The oxygen lance position is controlled at 1.8m in the early stage of oxygen blowing, and the bottom blowing argon flow is controlled at 400Nm 3 / h, the oxygen lance position is controlled at 1.75m in the middle stage of oxygen blowing, and the bottom blowing argon flow is controlled at 350Nm 3 / h, the oxygen lance position is controlled at 1.55m in the late stage of oxygen blowing, and the bottom blowing argon flow is controlled at 400Nm 3 / h, the oxygen blowing time is 11min, the example slagging material only uses light burned dolomite, the addition amount is 11kg per ton of steel, the first batch of light burned dolomite is added at the beginning of the blowing oxygen step to 35%, the addition amount is 1100kg, the second batch is added at the beginning of the blowing oxygen step to 70%, the addition amount is 680kg. The oxygen pressure is controlled at 0.70-0.85Mpa during the oxygen blowing process, and the oxygen supply intensity is 2.9-3.6 Nm 3 / (t﹒min), the final temperature is 1630℃, and the composition of the molten steel after tapping is: C:0.08%, P:0.075%, Cu:0.26%. The amount of new slag generated in the converter is 3.56 tons, the total iron content in the final slag of the converter is 19.44%, and the total amount of iron elements in the slag is 692kg. Example 2

[0023] A steel plant 150t converter, semi-steel loading capacity of 167t, the composition of the semi-steel used is: C:3.1%, Si:0.008%, Ti:0.005%, Mn:0.015%, P:0.110%, S:0.076%.

[0024] Converter slag addition amount is 22kg / t, the total amount of scrap steel accounts for 35%, SPA-H slab addition amount is 40kg / t, the total amount of scrap steel accounts for 65%, the composition of the converter slag used is: CaO%:32%, SiO2%:6.5%, MgO%:6.2%, P%:5.1%, S%:0.35%.

[0025] The oxygen lance position is controlled at 1.8m in the early stage of oxygen blowing, and the bottom blowing argon flow is controlled at 400Nm 3 / h, the oxygen lance position in the middle stage of oxygen blowing is controlled at 1.72m, and the bottom blowing argon flow rate is controlled at 350Nm 3 / h, the oxygen lance position in the later stage of oxygen blowing is controlled at 1.55m, and the bottom blowing argon flow rate is controlled at 400Nm 3 / h, oxygen blowing time 11min, the embodiment of the slag making material only uses light-burned dolomite, the addition amount is 8kg per ton of steel, the first batch of light-burned dolomite is added when the blowing oxygen step reaches 30%, the addition amount is 900kg, the second batch is added when the blowing oxygen step reaches 60%, the addition amount is 400kg. The oxygen pressure of the oxygen blowing process is controlled at 0.70-0.85Mpa, and the oxygen supply intensity is 2.9-3.6 Nm 3 The final temperature was 1642°C (t / min). The composition of the molten steel sample after tapping was as follows: C: 0.07%, P: 0.082%, Cu: 0.28%. The newly generated slag in the converter was approximately 2.6 tons, and the total iron content of the final converter slag was 18.58%, with a total iron content of 483 kg. Example 3

[0026] A steel plant has a 150t converter with a semi-steel loading of 166t. The semi-steel composition used is: C: 2.9%, Si: 0.006%, Ti: 0.006%, Mn: 0.011%, P: 0.133%, S: 0.080%.

[0027] The amount of converter slag added is 18 kg / t, accounting for 32% of the total scrap steel; the amount of SPA-H slab added is 38 kg / t, accounting for 68% of the total scrap steel. The composition of the converter slag used is: CaO%: 34%, SiO2%: 6.5%, MgO%: 6.9%, P%: 5.4%, S%: 0.35%.

[0028] The oxygen lance position in the early stage of oxygen blowing is controlled at 1.85m, and the bottom blowing argon flow rate is controlled at 400Nm 3 / h, the oxygen lance position in the middle stage of oxygen blowing is controlled at 1.75m, and the bottom blowing argon flow rate is controlled at 350Nm 3 / h, the oxygen lance position in the later stage of oxygen blowing is controlled at 1.60m, and the bottom blowing argon flow rate is controlled at 400Nm 3 / h, oxygen blowing time 12min, the embodiment of the slag making material only uses light-burned dolomite, the addition amount is 10kg per ton of steel, the first batch of light-burned dolomite is added when the blowing oxygen step reaches 30%, the addition amount is 900kg, the second batch is added when the blowing oxygen step reaches 70%, the addition amount is 720kg. The oxygen pressure of the oxygen blowing process is controlled at 0.70-0.85Mpa, and the oxygen supply intensity is 2.9-3.6 Nm 3The final temperature was 1640°C (t / min). After tapping, the molten steel sample contained 0.08% C, 0.075% P, and 0.27% Cu. The newly generated slag in the converter weighed approximately 3.2 tons, with a total iron content of 19.13% and a total iron content of 612 kg. Example 4

[0029] A steel plant has a 150t converter with a semi-steel loading of 165t. The semi-steel composition used is: C: 2.5%, Si: 0.005%, Ti: 0.020%, Mn: 0.005%, P: 0.100%, S: 0.052%.

[0030] The amount of converter slag added is 25kg / t, accounting for 36% of the total scrap steel; the amount of SPA-H slab added is 45kg / t, accounting for 64% of the total scrap steel. The composition of the converter slag used is: CaO%: 30.1%, SiO2%: 9.95%, MgO%: 5.1%, P%: 7.9%, S%: 0.95%.

[0031] The oxygen lance position in the early stage of oxygen blowing is controlled at 1.82m, and the bottom blowing argon flow rate is controlled at 400Nm 3 / h, the oxygen lance position in the middle stage of oxygen blowing is controlled at 1.70m, and the bottom blowing argon flow rate is controlled at 350Nm 3 / h, the oxygen lance position in the later stage of oxygen blowing is controlled at 1.58m, and the bottom blowing argon flow rate is controlled at 400Nm 3 / h, oxygen blowing time 11min, the embodiment of the slag making material only uses light-burned dolomite, the addition amount is 9kg per ton of steel, the first batch of light-burned dolomite is added when the blowing oxygen step reaches 30%, the addition amount is 1000kg, the second batch is added when the blowing oxygen step reaches 70%, the addition amount is 460kg. The oxygen pressure of the oxygen blowing process is controlled at 0.70-0.85Mpa, and the oxygen supply intensity is 2.9-3.6 Nm 3 The final temperature was 1650°C / (t / min). After tapping, the molten steel sample contained the following components: C: 0.10%, P: 0.07%, and Cu: 0.35%. The newly generated slag in the converter weighed approximately 2.92 tons, and the total iron content of the final converter slag was 20.12%, for a total iron content of 588 kg. Example 5

[0032] A steel plant has a 150t converter with a semi-steel loading of 175t. The semi-steel composition used is: C: 3.5%, Si: 0.020%, Ti: 0.004%, Mn: 0.030%, P: 0.980%, S: 0.033%.

[0033] The amount of converter slag added was 11 kg / t, and the proportion of scrap steel in the total amount was 28%. The amount of SPA-H slab added was 29 kg / t, and the proportion of scrap steel in the total amount was 72%. The composition of the converter slag used was: CaO%: 30.5%, SiO2%: 8.5%, MgO%: 5.2%, P%: 7.4%, and S%: 0.25%.

[0034] The lance position was controlled at 1.83 m before oxygen blowing, and the bottom argon flow rate was controlled at 400 Nm 3 / h. The lance position was controlled at 1.74 m during oxygen blowing, and the bottom argon flow rate was controlled at 350 Nm 3 / h. The lance position was controlled at 1.57 m after oxygen blowing, and the bottom argon flow rate was controlled at 400 Nm 3 / h. The oxygen blowing time was 11 min. The light-burned dolomite was used as the slag-making material, and the amount added was 10 kg per ton of steel. The first batch of light-burned dolomite was added at the beginning of the blowing oxygen step to 40%, and the amount added was 1200 kg. The second batch of light-burned dolomite was added at the beginning of the blowing oxygen step to 70%, and the amount added was 600 kg. The oxygen pressure during oxygen blowing was controlled at 0.70-0.85 Mpa, and the oxygen supply intensity was 2.9-3.6 Nm 3 / (t·min). The final temperature was 1645°C, and the composition of the molten steel after tapping was: C: 0.07%, P: 0.01%, and Cu: 0.25%. The amount of newly generated slag in the converter was 3.60 tons, the total iron content in the final slag was 19.08%, and the total amount of iron elements in the slag was 687 kg.

[0035] Comparative Example (Conventional Operation) A 150 t converter of a certain steel plant was used, and the amount of semi-steel loaded was 167 t. The composition of the semi-steel used was: C: 3.0%, Si: 0.007%, Ti: 0.007%, Mn: 0.010%, P: 0.119%, and S: 0.077%.

[0036] The amount of SPA-H slab added was 55 kg / t, and the proportion of scrap steel in the total amount was about 100%.

[0037] The lance position was controlled at 1.80 m before oxygen blowing, and the bottom argon flow rate was controlled at 400 Nm 3 / h. The lance position was controlled at 1.70 m during oxygen blowing, and the bottom argon flow rate was controlled at 350 Nm 3 / h. The lance position was controlled at 1.60 m after oxygen blowing, and the bottom argon flow rate was controlled at 400 Nm 3h, blowing oxygen time 12 min, the conventional operation of the slag material only using light-burned dolomite, the amount of 14 kg per ton of steel, light-burned dolomite first batch of adding time for blowing oxygen step to 30% to start adding, the amount of 1400 kg, the second batch of adding time for blowing oxygen step to 70% to start adding, the amount of 900 kg. Oxygen blowing process oxygen pressure control for 0.70-0.85 Mpa, oxygen supply intensity for 2.9-3.6 Nm 3 / (t.min), end point temperature 1620℃, after the end of tapping molten steel sampling composition: C: 0.07%, P: 0.076%, Cu: 0.26%. Converter new slag amount is about 4.6 tons, converter final slag total iron content 17.45%, the total amount of iron elements in the slag about 803 kg.

[0038] The above examples are only to illustrate and not to limit the technical solutions of the present application, although the present application is described in detail with reference to the above examples, those skilled in the art should understand that various modifications and changes can be made to the exemplary embodiments of the present application without departing from the spirit and scope defined by the claims.

Claims

1. A low cost smelting method of semi-killed steel SPA-H weathering resistant steel, characterized in that, It comprises the following steps: The scrap steel is directly added into the converter through a hopper before the converter is charged with iron; the converter is charged with the vanadium extraction semi-steel and then oxygen blowing is started; the magnesium slag is added during the oxygen blowing process to form slag; the converter is controlled to remove phosphorus by changing the oxygen lance position, oxygen supply intensity and slag adding time; and the qualified molten steel is obtained by completing the converter decarburization.

2. A low cost semi-steel making process for smelting SPA-H weathering steel according to claim 1, characterized in that, The scrap steel comprises the dry converter steel slag after rolling and crushing, the SPA-H weathering steel slab head tail, copper plate or other copper alloy.

3. A low cost semi-steel making process of SPA-H weathering steel according to claim 2, characterized in that, The mass content of each component in the scrap steel is: 28%-36% of the converter steel slag, 64%-72% of the SPA-H weathering steel slab head tail, and the copper plate or other copper alloy calculated according to the steel grade requirement and copper content. The dry converter steel slag after rolling and crushing is treated by rolling and crushing to reach the index of maximum diameter <30 cm, and the composition and mass content meet: CaO%>30%, SiO2%<10%, MgO%>5%, P%<8%, and S%<1%.

4. A low cost semi-steel making process of SPA-H weathering steel according to claim 1, characterized in that, The magnesium slag comprises dolomite or light-burned dolomite, the mass content of MgO in the light-burned dolomite is 35-45%, and the mass content of MgO in the dolomite is 25-35%; the magnesium slag is added according to the equivalent replacement of MgO content, and the addition amount of the light-burned dolomite alone is 8-11 kg / ton of steel, and the addition amount of the dolomite alone is 11-15 kg / ton of steel.

5. A low cost semi-steel making process of SPA-H weathering steel according to claim 1, characterized in that, The magnesium slag is added in two batches, the first batch is added at the beginning of the blowing oxygen step to 30%-40%, and the addition amount is 60%-80% of the total mass; the second batch is added at the beginning of the blowing oxygen step to 60%-80%, and the addition amount is 20%-40% of the total mass.

6. A low cost semi-steel making process of SPA-H weathering steel according to claim 1, characterized in that, The oxygen lance position is controlled in the high-low-low mode, the lance position in the early stage of the oxygen blowing process is 1.8-1.85 m, the lance position in the middle stage is 1.7-1.75 m, and the lance position in the late stage is 1.55-1.6 m.

7. A low cost semi-steel making process of SPA-H weathering steel according to claim 1, characterized in that, The oxygen pressure in the oxygen blowing process is 0.70-0.85 MPa, and the oxygen supply intensity is 2.9-3.6 Nm 3 The terminal temperature is 1630-1650℃.

8. A low cost semi-steel making process of SPA-H weathering steel according to claim 1, characterized in that, The composition and mass content of the semi-steel are: C: 2.5-3.5%, Si: 0.005-0.02%, Ti: 0.004-0.02%, Mn: 0.005-0.03%, and the balance is iron and other unavoidable elements.

9. A low cost semi-steel making process of SPA-H weathering steel according to claim 1, characterized in that, The composition and mass content of the qualified molten steel are: C: 0.07-0.10%, P: 0.07-0.10%, Cu: 0.25-0.35%, and the balance is iron and other unavoidable elements.