Rapid fettling method for converter

Abstract

The invention relates to the technical field of new metallurgical processes, in particular to a rapid converter fettling method which adopts fused magnesia, a binding agent and an additive as fettling materials, the fettling materials are flatly laid on the front large face and the rear large face of a converter hearth, oxygen is blown in through an oxygen blowing pipe with the top end closed and the two sides provided with inclined spraying holes to conduct combustion-supporting sintering to form a carbon structure, and the fettling effect is achieved. The method has the beneficial effects that the sintering efficiency is improved, the sintering oxygen lance is improved, the sintering combustion-supporting oxygen amount of the fettling material is increased, the sintering time is shortened, and the production operation rate is increased; the method meets the fettling requirement, and the sintering time is obviously shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of new metallurgical processes, and particularly to a method for quickly repairing a converter furnace. Background Art

[0002] During the process of charging molten iron and scrap steel into the converter, the front and rear large surfaces of the furnace hearth will be subjected to severe mechanical impacts; during the blowing process, the strong physical and chemical reactions inside the furnace hearth will cause serious erosion and defects to the inner lining of the furnace hearth. Therefore, the scientific maintenance of the front large surface of the converter is the guarantee for the efficient and safe operation of the converter.

[0003] The methods for maintaining the converter furnace lining usually combine repair materials, masonry, and operation processes, etc.; in traditional converter carbon-based hot-state feeding repair materials, self-flowing repair materials are most commonly used to repair the front and rear large surfaces of the furnace hearth. It is mainly composed of fused magnesia as the main raw material, asphalt as the binder, and a certain amount of additives, dust removers, and explosion-proof agents are added. However, during the furnace repair process with asphalt as the binder, firstly, it needs to form a carbon structure in combination with the furnace lining under high-temperature conditions, and secondly, it needs oxygen for long-time sintering. If the sintering is not sufficient, it will lead to problems such as low density, high porosity, and the formation of a sandwich layer in the carbon structure formed with the furnace lining, causing splashing and introducing S, C, etc. into the furnace.

[0004] In the traditional furnace repair process, oxygen is blown from the end of the oxygen blowing pipe at the oxygen blowing nozzle, and the oxygen blowing area is small and the oxygen blowing efficiency is low. The defects of the converter are usually in the front and rear large surfaces of the converter furnace hearth. The oxygen blowing nozzle cannot directly face the large defective surface to blow oxygen and sinter the repair material, which easily causes uneven sintering of the repair material, poor furnace repair effect, poor furnace repair quality, long furnace repair time, and delays the orderly production of the converter.

[0005] And 1 ton of repair material needs to be sintered for 40 - 60 minutes, and the total time for one furnace repair is 55 - 65 minutes. Moreover, the furnace needs to be repaired once every less than 20 heats, and the furnace repair frequency is high, seriously affecting the furnace repair and production cycle. Therefore, how to shorten the furnace repair sintering time and improve the furnace repair quality is an urgent problem to be solved at present. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a method for quickly repairing a converter furnace. This method uses fused magnesia, a binder, and additives as repair materials, which are laid flat on the front and rear large surfaces of the converter furnace hearth. Oxygen is blown through an oxygen blowing pipe with a closed top and inclined spray holes on both sides to assist combustion and sinter to form a carbon structure, achieving the effect of furnace repair, improving the sintering efficiency, improving the sintering oxygen blowing pipe, increasing the amount of oxygen for sintering the repair material, shortening the sintering time, and improving the production operation rate; this method meets the furnace repair requirements and significantly reduces the sintering time.

[0007] In order to achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0008] A method for rapid furnace repair of a converter. The method for rapid furnace repair of the converter is to form a carbon structure by using an oxygen blowing pipe with lateral spray holes to assist in burning and sintering the furnace repair materials on the front and rear large surfaces of the converter furnace. The specific content of the method for rapid furnace repair of the converter includes the following:

[0009] S1: Before furnace repair

[0010] At the end of steel tapping for furnace repair, the oxygen concentration ≤ 500 ppm, the temperature ≥ 1680 °C, and the first tilting of the furnace;

[0011] After slag splashing for furnace lining protection, pour out the molten slag completely;

[0012] After pouring out the slag, use a laser thickness gauge to detect that the thickness of the lowest point on the large surface of the furnace wall ≤ 700 mm, and the average furnace wall thickness ≤ 1000 mm;

[0013] S2: Furnace repair operation

[0014] Open the front fire door of the furnace. The crane aligns the scrap steel bucket filled with furnace repair materials with the furnace mouth. The lower edge of the scrap steel bucket leans against the furnace mouth. Add 1000 - 1200 kg of furnace repair materials into the furnace, close the front fire door of the furnace, level and shake the furnace repair materials in the furnace. The final tilting angle of the converter is 90 ± 5 °;

[0015] Use the oxygen blowing pipe to blow oxygen. The oxygen assists in burning and sintering the furnace repair materials. The end of the oxygen blowing pipe is blocked. A number of inclined spray holes are arranged on both sides of the oxygen blowing pipe. The end of the oxygen blowing pipe abuts against the bottom of the converter furnace. The end of the oxygen blowing pipe does not blow oxygen, and oxygen is blown through a number of spray holes on both sides. A number of spray holes on both sides blow oxygen on the damaged large surface. The blowing time is 20 - 50 min, and the furnace repair materials in the furnace are assisted in burning and sintering to form a carbon structure for furnace repair;

[0016] S3: After furnace repair

[0017] After adding and sintering the furnace repair materials, use a laser thickness gauge to detect that the thickness of the lowest point on the large surface of the furnace wall is ≥ 800 mm, and the average furnace wall thickness ≥ 1150 mm. When the laser thickness gauge detects that the thickness of the lowest point on the large surface of the furnace wall is ≤ 700 mm and the average furnace wall thickness ≤ 1000 mm during the operation of the converter, perform rapid furnace repair again.

[0018] Further, on both sides of the pipe body of the oxygen blowing pipe in step S2, a number of inclined spray holes staggered and oppositely opened at different lengths from the end of the oxygen blowing pipe are provided.

[0019] Further, the furnace repair materials in step S2 are composed of the following raw materials in parts by weight: 74 - 84 parts of fused magnesia; 15 - 25 parts of binder; 0.5 - 1.5 parts of additive.

[0020] Further, the binder is a combination of asphalt and resin, and is mixed in a weight ratio of 2.25 - 3:1.50.

[0021] Further, during the first tapping process in step S1, it is prohibited to blow oxygen into the molten steel.

[0022] Further, after furnace repair in step S3, in the molten steel composition in the converter, S≤0.02% and C≤0.01%.

[0023] Further, the end of the oxygen blowing pipe in step S2 is blocked, and the blocking distance is the distance from the furnace bottom to the damaged positions on the front and rear large surfaces of the converter hearth.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) This method uses fused magnesia as the main material, combines asphalt and resin as the binder, and adds additives as the furnace repair material for furnace repair. The furnace repair material has good fluidity and good sintering effect, avoids the low density of the carbon structure formed by the furnace repair material and the furnace lining, reduces the sintering porosity, improves the furnace repair quality, the converter has a long operation cycle after furnace repair, and the orderly production time of the converter is long.

[0026] (2) This method detects the furnace wall through a laser thickness gauge to accurately control the furnace repair cycle. After the converter continuously produces 20 furnaces, when the measured furnace wall thickness is less than the set value, furnace repair is carried out, accurately controlling the furnace repair rhythm, extending the furnace repair cycle, saving the furnace repair cost, and reducing the working frequency of the operators.

[0027] (3) The oxygen blowing pipe is improved in design. A number of inclined spray holes are arranged on both side walls of the oxygen blowing pipe. The positions of the a number of inclined spray holes are staggered and the distances are unequal, improving the uniformity of oxygen blowing, increasing the oxygen blowing area, making the sintering of the furnace repair material uniform, improving the furnace repair quality. The a number of spray holes increase the oxygen blowing volume, improve the oxygen blowing effect, improve the sintering efficiency, not only ensure the furnace repair effect of the converter, but also shorten the sintering time of the furnace repair material, improve the production operation rate, and improve the oxygen utilization rate.

[0028] (4) The end of the oxygen blowing pipe is blocked, and the blocking length is from the furnace bottom to the damaged positions on the front and rear large surfaces of the hearth. The end of the oxygen blowing pipe abuts against the converter furnace bottom, and the spray holes on the side of the oxygen blowing pipe are exactly at the damaged positions. The end of the oxygen blowing pipe is positioned and supported on the furnace bottom, improving the accuracy of the oxygen blowing position of the spray holes, increasing the reliability of the spray hole oxygen blowing, having a high oxygen utilization rate, not blowing oxygen at the end, preventing the bottom of the converter from being burned, increasing the oxygen blowing volume of the side spray holes, and improving the oxygen blowing efficiency.

[0029] (5) The furnace repair sintering time is short, avoiding the generation of a sandwich layer causing splashing. There is no splashing after furnace repair, and the furnace repair effect is good. After furnace repair, in the molten steel composition produced by the converter, S≤0.02%; C≤0.01%, avoiding accidents of excessive S and C in the molten steel and ensuring the production quality of the molten steel. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of the oxygen blowing pipe provided by the present invention.

[0031] Figure 2 It is an axonometric view of the oxygen lance structure provided by the present invention.

[0032] In the figure: 1. Oxygen lance; 2. Spray hole; 3. Pipe wall; 4. Plugging; α. Inclination angle. Specific embodiments

[0033] The following further describes the specific embodiments of the present invention with reference to the accompanying drawings:

[0034] Example 1:

[0035] I. Before furnace patching:

[0036] 1. The oxygen concentration at the end of steelmaking for furnace patching is 478 ppm, the temperature is 1683 °C, and the first tapping is carried out.

[0037] 2. After slag splashing for furnace protection, pour out the molten slag completely.

[0038] 3. After pouring out the slag, use a laser thickness gauge to detect the thickness of the lowest point on the large surface of the furnace wall is 688 mm, and the average furnace wall thickness is 929 mm.

[0039] II. Furnace patching operation:

[0040] 1. Open the front furnace fire door. The crane aligns the scrap steel bucket filled with furnace patching materials with the furnace mouth. The lower edge of the scrap steel bucket leans on the furnace mouth, and 1088 kg of furnace patching materials are added into the furnace. The furnace patching materials are composed of 79 parts of fused magnesia, 20 parts of binder, and 1 part of additive. The binder is asphalt and resin, and asphalt and resin are mixed in a mass ratio of 2.44:1.50. Close the front furnace fire door, level and shake the furnace patching materials in the furnace, add the furnace patching materials to the damaged position, shake the converter to make the furnace patching materials spread flat on the damaged position, and the final tilting angle of the converter is 90°.

[0041] 2. Use oxygen for combustion assistance. The diameter of the oxygen lance 1 is 30 mm. Perform the plugging operation 4 on the end of the oxygen lance 1 pipe opening, and the plugging distance is 500 mm. Four spray holes 2 with an inclination angle α = 30° with the pipe wall 3 are opened on one side of the pipe wall 3 at distances of 600, 900, 1200, and 1500 mm from the oxygen lance 1 pipe opening; at distances of 550, 850, 1150, and 1450 mm from the pipe opening, four other spray holes 2 with the same inclination angle α = 30° are opened on the opposite side of the pipe wall 3. The end of the oxygen lance 1 abuts against the bottom of the converter. The side spray holes 2 of the oxygen lance 1 are exactly located at the damaged positions on the front and rear large surfaces of the converter furnace chamber. The oxygen lance 1 is changed from the traditional single-hole oxygen blowing to two rows of 8 spray holes 2 for simultaneous oxygen blowing to assist in burning and sintering the furnace patching materials. The oxygen blowing area is increased, the oxygen blowing amount is increased, the oxygen blowing sintering efficiency is improved, the sintering furnace patching time is shortened, the oxygen blowing sintering time is 22 min, and the sintering carbon structure of the furnace patching materials at the weak parts of the furnace wall in the furnace is carried out.

[0042] III. After furnace patching:

[0043] After feeding and sintering, the thickness of the lowest point on the large surface of the furnace wall was measured by a laser thickness gauge to be 843 mm, and the average furnace wall thickness was 1198 mm. After the converter ran for 23 heats, the thickness of the lowest point on the large surface of the furnace wall was measured by a laser thickness gauge to be 772 mm, and the average furnace wall thickness was 1053 mm.

[0044] Example 2:

[0045] I. Before furnace patching:

[0046] 1. The oxygen concentration at the end of steel tapping for furnace patching was 496 ppm, the temperature was 1688 °C, and the first tilting of the furnace was carried out.

[0047] 2. After slag splashing for furnace protection, the molten slag was emptied.

[0048] 3. After emptying the slag, the thickness of the lowest point on the large surface of the furnace wall was measured by a laser thickness gauge to be 663 mm, and the average furnace wall thickness was 997 mm.

[0049] II. Furnace patching operation:

[0050] 1. Open the front fire door of the furnace. The overhead crane aligns the scrap steel bucket filled with furnace patching materials with the furnace mouth, and the lower edge of the scrap steel bucket leans against the furnace mouth. 1074 kg of furnace patching materials are added into the furnace. The furnace patching materials are composed of 77 parts of fused magnesia, 22 parts of binder, and 1 part of additive. The binder is asphalt and resin, and asphalt and resin are mixed in a weight ratio of 2.72:1.50. Close the front fire door of the furnace, level and shake the furnace patching materials in the furnace, and the final tilting angle of the converter is 91°.

[0051] 2. Use oxygen for combustion support. The diameter of oxygen lance 1 is 30 mm. Perform operation 4 on the end of the oxygen lance 1 nozzle for plugging, and the plugging distance is 500 mm. Four spray holes 2 with an inclination angle α = 30° to the pipe wall 3 are opened on one side of the pipe wall 3 at distances of 700, 900, 1100, and 1300 mm from the nozzle of the oxygen lance 1; at distances of 650, 850, 1050, and 1250 mm from the nozzle, four other spray holes 2 with the same inclination angle α = 30° are opened on the opposite side of the pipe wall 3. The end of the oxygen lance 1 abuts against the bottom of the converter, and the side spray holes 2 of the oxygen lance 1 are exactly located at the defective positions on the front and rear large surfaces of the converter hearth. The oxygen lance 1 is changed from the traditional single-hole oxygen blowing to the simultaneous oxygen blowing of two rows of 8 spray holes 2 to sinter the furnace patching materials. The oxygen blowing area is increased, the oxygen blowing volume is increased, the oxygen blowing sintering efficiency is improved, the sintering and furnace patching time is shortened, the oxygen blowing sintering time is 28 min, and the sintered carbon structure of the furnace patching materials at the weak parts of the furnace wall in the furnace is carried out.

[0052] III. After furnace patching:

[0053] After feeding and sintering, the thickness of the lowest point on the large surface of the furnace wall was measured by a laser thickness gauge to be 860 mm, and the average furnace wall thickness was 1181 mm. After the converter ran for 22 heats, the thickness of the lowest point on the large surface of the furnace wall was measured by a laser thickness gauge to be 735 mm, and the average furnace wall thickness was 1062 mm.

[0054] Example 3:

[0055] I. Before furnace patching:

[0056] 1. The oxygen concentration at the end of steel tapping for furnace patching is 454 ppm, the temperature is 1684 °C, and the first tilting of the converter is carried out;

[0057] 2. After slag splashing for furnace lining protection, pour out all the molten slag;

[0058] 3. After pouring out the slag, use a laser thickness gauge to detect that the thickness of the lowest point on the large surface of the furnace wall is 639 mm, and the average furnace wall thickness is 992 mm.

[0059] II. Furnace patching operation:

[0060] 1. Open the front fire door of the furnace. The overhead crane aligns the scrap steel bucket filled with furnace patching materials with the furnace mouth. The lower edge of the scrap steel bucket leans against the furnace mouth, and 1143 kg of furnace patching materials are added into the furnace. The furnace patching materials are composed of 82 parts of fused magnesia, 17 parts of binder, and 1 part of additive. The binder is asphalt and resin, and asphalt and resin are mixed in a mass ratio of 2.45:1.50. Close the front fire door of the furnace, level and shake the furnace patching materials in the furnace, and the final tilting angle of the converter is 90°;

[0061] 2. Use oxygen for combustion support. The diameter of oxygen lance 1 is 30 mm. Perform operation 4 on the end of the oxygen lance 1 nozzle for plugging, and the plugging distance is 500 mm. At 550, 800, 1100, and 1400 mm from the nozzle of oxygen lance 1, open 4 spray holes 2 on one side of the pipe wall 3 with an inclination angle α = 30° to the pipe wall 3; at 600, 850, 1150, and 1450 mm from the nozzle, open another 4 spray holes 2 with the same inclination angle α = 30° on the opposite side of the pipe wall 3. The end of oxygen lance 1 abuts against the bottom of the converter, and the side spray holes 2 of oxygen lance 1 are exactly located at the defective positions on the front and rear large surfaces of the converter hearth. The oxygen lance 1 is changed from the traditional single-hole oxygen blowing to the simultaneous oxygen blowing of two rows of 8 spray holes 2 to sinter the furnace patching materials. The oxygen blowing area is increased, the oxygen blowing volume is increased, the oxygen blowing sintering efficiency is improved, the sintering and furnace patching time is shortened, the oxygen blowing sintering time is 23 min, and the sintered carbon structure of the furnace patching materials at the weak parts of the furnace wall in the furnace is carried out.

[0062] III. After furnace patching:

[0063] After feeding and sintering, use a laser thickness gauge to detect that the thickness of the lowest point on the large surface of the furnace wall is 823 mm, and the average furnace wall thickness is 1172 mm. After the converter runs for 20 heats, use a laser thickness gauge to detect that the thickness of the lowest point on the large surface of the furnace wall is 769 mm, and the average furnace wall thickness is 1088 mm.

[0064] Effect evaluation:

[0065] Test results

[0066]

[0067]

[0068] In Examples 1 - 3, the furnace patching time is shortened, the converter operation cycle exceeds 20 heats, the converter operation cycle is long, the C and S contents in the molten steel composition tapped from the converter meet the requirements, and there is no splashing after furnace patching. This furnace patching method is feasible.

[0069] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and its concept of the present invention, making equivalent replacements or changes should be covered within the protection scope of the present invention.

Claims

1. A method for rapid converter repair, characterized in that: The method for rapidly repairing a converter is to form a carbon structure by using an oxygen blowing pipe provided with lateral spray holes to assist combustion and repair charge on the front and rear large surfaces of the converter furnace. The method for rapidly repairing a converter specifically includes the following contents: S1: Before repairing the furnace The oxygen concentration at the end of the steel tapping is ≤500ppm, the temperature is ≥1680℃, and the furnace is turned over once; After splashing slag to protect the furnace, pour out the molten slag; After slag pouring, use a laser thickness gauge to detect the thickness of the lowest point of the furnace wall ≤700mm, and the average furnace wall thickness ≤1000mm; S2: Furnace repair operation Open the fire-blocking door in front of the furnace, align the scrap steel bucket with the furnace mouth with the overhead crane, and place the lower edge of the scrap steel bucket against the furnace mouth. Add 1000-1200kg of the furnace charge into the furnace, close the fire-blocking door in front of the furnace, level and shake the furnace charge, and the final tilting angle of the converter is 90±5°; Use oxygen blowing pipe to blow oxygen, oxygen assists combustion and repairs the charge, the end of the oxygen blowing pipe is blocked, a number of oblique spray holes are set on both sides of the oxygen blowing pipe, the end of the oxygen blowing pipe is against the bottom of the converter, the end of the oxygen blowing pipe does not blow oxygen, but blows oxygen from a number of spray holes on both sides, the spray holes on both sides blow oxygen to the large defective surface, the oxygen blowing time is 20 to 50 minutes, and the charge in the furnace is assisted in combustion to form a carbon structure repair; S3: After furnace repair After the supplementary charge is sintered, the laser thickness gauge is used to detect the thickness of the lowest point of the large surface of the furnace wall to be ≥800mm, and the average furnace wall thickness is ≥1150mm. After the converter is running, the laser thickness gauge is used to detect the thickness of the lowest point of the large surface of the furnace wall to be ≤700mm. When the average furnace wall thickness is ≤1000mm, the furnace is quickly supplemented again.

2. A method for rapid converter repair according to claim 1, characterized in that: In step S2, a plurality of oblique spray holes are arranged on both sides of the oxygen blowing pipe body and are staggered and opposite to each other at different lengths from the end of the oxygen blowing pipe.

3. A method for rapid converter repair according to claim 1, characterized in that: The furnace filling material in step S2 is composed of the following raw materials in parts by weight: 74-84 parts of fused magnesia; 15-25 parts of binder; and 0.5-1.5 parts of additives.

4. A method for rapid converter repair according to claim 3, characterized in that: The binder is a combination of asphalt and resin, which are mixed in a weight ratio of 2.25-3:1.

50.

5. The method for rapid converter repair according to claim 1, characterized in that: In the step S1, spot blowing of molten steel is prohibited during the first pouring process.

6. A method for rapid converter repair according to claim 1, characterized in that: After the furnace is replenished in step S3, the composition of the molten steel in the converter is S≤0.02%, and C≤0.01%.

7. A method for rapid converter repair according to claim 1, characterized in that: The end of the oxygen blast pipe is sealed in step S2, and the sealing distance is the distance from the furnace bottom to the front and rear large surface defect positions of the converter furnace.

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