A method for recycling cold heading steel refining slag

Abstract

The application discloses a cold upsetting steel refining slag recycling method, which adds the slag generated in continuous casting to a refining process to recycle and reuse. When recycling and reusing, the slag is utilized by setting a refining slag recycling mode. The application avoids the reduction of sulfur capacity in the recycling process by supplementing slag material. The total amount of refining slag is controlled within a stable weight range by discharging part of the top slag and supplementing slag material. The composition stability of the refining slag is ensured by ladle timing ladle operation on the basis of stable initial casting residual amount. The addition amount of the top slag material is determined according to whether the refining slag needs to be recycled, so that the flexibility and consistency of the process execution are ensured. The application can effectively reduce the consumption of slag material and the output of refining slag, and can ensure the stability of the composition of the refining slag, and guarantee the flexibility, stability and on-site executability of the process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steelmaking and refining slag recycling in the metallurgical industry, and particularly relates to a cold upsetting steel refining slag recycling method. BACKGROUND

[0002] In the steelmaking process of high-quality steel, an off-furnace refining operation is usually involved, that is, a series of operations such as desulfurization, temperature rise and inclusion removal are performed on molten steel by means of ladle top slag making. In order to ensure the off-furnace refining effect of molten steel, the amount of slag per ton of steel is usually 8-15 Kg / t. After the refining top slag is poured into a slag basin after the molten steel is cast, it is usually transported to a steel slag treatment plant for treatment. This type of slag has a large amount of slag, often with some cold steel, and it is difficult to achieve complete separation of steel and slag. It also causes a large amount of manpower and material resources consumption. SUMMARY

[0003] In view of the deficiencies in the prior art, the present application provides a cold upsetting steel refining slag recycling method, which can effectively reduce the consumption of slag-making materials and the output of refining slag, while ensuring the stability of the refining slag composition, and the process flexibility, stability and on-site executability can be guaranteed.

[0004] The present application achieves the above technical purpose by the following technical means.

[0005] A cold upsetting steel refining slag recycling method comprises the following steps:

[0006] The slag generated by continuous casting is added to the refining process for recycling and reuse.

[0007] During recycling and reuse, new slag is made in the initial furnace, from the first converter blowing furnace to the completion of the first ladle continuous casting, the converter blowing furnace is the first furnace for refining slag recycling, from the second converter blowing furnace to the completion of the second ladle continuous casting, the converter blowing furnace is the second furnace for refining slag recycling, and so on, until the nth furnace for refining slag recycling, n furnaces constitute a round, and there are N rounds in total.

[0008] The slag of the first furnace in the first round is added to the first furnace in the second round for further processing, the slag generated by the first furnace in the second round is added to the first furnace in the third round for further processing, and so on, until the Nth round.

[0009] Further technical solutions, if the cold upsetting steel production process includes converter smelting, refining and continuous casting three processes, the refining slag recycling mode is: the 1, 2, 3, 4 furnace of the converter smelting furnace is the process of making new slag, the slag produced after the 1, 2, 3, 4 furnace of the smelting furnace is refined and continuously cast is added to the 5, 6, 7, 8 furnace of the smelting furnace respectively, similarly, the slag produced after the 5, 6, 7, 8 furnace of the smelting furnace is refined and continuously cast is added to the 9, 10, 11, 12 furnace of the smelting furnace respectively, and so on.

[0010] Further technical solutions, if the cold upsetting steel production process includes converter smelting, refining, vacuum furnace smelting and continuous casting four processes, the refining slag recycling mode is: the 1, 2, 3, 4, 5 furnace of the converter smelting furnace is the process of making new slag, the slag produced after the 1, 2, 3, 4, 5 furnace of the smelting furnace is refined and continuously cast is added to the 6, 7, 8, 9, 10 furnace of the smelting furnace respectively, similarly, the slag produced after the 6, 7, 8, 9, 10 furnace of the smelting furnace is refined and continuously cast is added to the 11, 12, 13, 14, 15 furnace of the smelting furnace respectively, and so on.

[0011] Further technical solutions, in the recycling and reuse process, the decrease of sulfur capacity in the reuse process is avoided by supplementing slag.

[0012] Further technical solutions, for CaO-SiO2-Al2O3 slag system, supplementing slag at the converter tapping, the slag includes lime and calcium aluminate, the addition amount is respectively:

[0013] Lime addition amount = new slag lime amount * 0.5 + (new slag lime amount / 6 - new slag lime amount / 3)

[0014] Calcium aluminate addition amount = new slag calcium aluminate amount * 0.5 - (new slag calcium aluminate / 6 - new slag calcium aluminate amount / 3).

[0015] Further technical solutions, in the recycling and reuse process, the total amount of refining slag is controlled within a stable weight range by discharging part of the top slag and supplementing slag; the discharging of the part of the top slag adopts a timing ladle turning method, which stably discharges 1 / 3-1 / 2 of the amount of refining slag in the ladle into the slag basin.

[0016] Further technical solutions, the timing ladle turning method is: the ladle is controlled by the crane to the surrounding of the slag basin to ensure that the steel slag can be turned into the slag basin, the auxiliary hook is jogged, and when the red slag flows out of the ladle opening, the auxiliary hook is jogged twice again and kept in this state for 8-10 seconds.

[0017] Further technical solutions, in the recycling process, on the basis of the initial casting allowance stability, through ladle timing ladle operation, ensure the refining slag composition stability, through the display of the ladle weighing equipment control initial casting allowance stability.

[0018] Further technical solutions, in the recycling process, according to whether the furnace needs to recover the refining slag to determine the amount of top slag material, to ensure the flexibility and consistency of the process: if not, add the amount of lime and calcium aluminate in the conventional production process, and if so, add the amount of lime and calcium aluminate in the complementary slag material.

[0019] The beneficial effects of the present application are:

[0020] (1) The present application adds the slag produced by continuous casting to the refining process for recycling and reuse, and through the reuse of refining slag, reduces the output of refining slag and improves the yield of molten steel;

[0021] (2) The present application further ensures the stability of the refining slag composition by ladle timing ladle operation on the basis of the initial casting allowance stability; and determines the amount of top slag material according to whether the furnace needs to recover the refining slag, to ensure the flexibility and on-site executability of the process;

[0022] (3) The method of the present application does not affect the refining effect of the refined molten steel;

[0023] (4) The present application improves the submerged arc heating effect in the early stage of refining by using hot molten slag, and reduces the refining power consumption. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The flow chart of the cold heading steel refining slag recycling method of the present application;

[0025] Figure 2 The schematic diagram of the refining slag recycling mode of the present application. DETAILED DESCRIPTION

[0026] The present application will be further described below in conjunction with the drawings and specific embodiments, but the scope of protection of the present application is not limited thereto.

[0027] As shown in Figure 1 , the cold heading steel refining slag recycling method of the present application specifically includes the following contents:

[0028] (1) Conventional cold heading steel production process scheme

[0029] 1) Converter

[0030] ① Converter tapping control target C≥0.08%, tapping temperature≥1600℃;

[0031] ② Tapping process with 50-100 Kg aluminum cake, low-nitrogen carburant, silicon manganese, ferrosilicon, medium-carbon ferromanganese, high-carbon ferrochrome added according to the composition of the steel grade for alloying;

[0032] ③ Top slag material using lime 300 Kg, calcium aluminate 350 Kg, added with the steel flow to ensure the slag surface fusion at the end of tapping;

[0033] 2) Refining

[0034] ④ After LF submerged arc stabilization, lime and fluorite are added to adjust the slag fluidity, and aluminum beans, carbide, and silicon carbide are used to deoxidize the slag surface to form white slag, with white slag retention time ≥ 15 min;

[0035] ⑤ Alloy fine adjustment using ferrosilicon, silicon manganese, medium-carbon ferromanganese, medium-carbon ferrochrome, and aluminum wire for aluminum adjustment;

[0036] ⑥ Calcium treatment using solid core pure calcium wire or silicon calcium wire, with a dosage of 80-150 m / furnace;

[0037] ⑦ Control soft blowing time ≥ 15 min;

[0038] 3) Continuous casting

[0039] ⑧ Continuous casting using a split-type nozzle package, with full-process protective casting, and superheat controlled at 20-35 ℃.

[0040] (2) Control of refining slag recycling mode

[0041] According to the refining rhythm of the molten steel, new slag is formed at the initial furnace, from the first furnace of converter blowing to the completion of the first package continuous casting, the converter blowing furnace is the first furnace for recycling of refining slag, from the second furnace of converter blowing to the completion of the second package continuous casting, the converter blowing furnace is the second furnace for recycling of refining slag, and so on.

[0042] Referring to Figure 2 , if the cold upsetting steel production process includes converter smelting, refining, and continuous casting three processes, the refining slag recycling mode is: the 1st, 2nd, 3rd, and 4th furnaces of the converter smelting furnace (initial furnace) are the new slag forming process, and the slags produced after the 1st, 2nd, 3rd, and 4th furnaces of the smelting furnace are subjected to refining and continuous casting, respectively, and are added to the 5th, 6th, 7th, and 8th furnaces of the smelting furnace. Similarly, the slags produced after the 5th, 6th, 7th, and 8th furnaces of the smelting furnace are subjected to refining and continuous casting, respectively, and are added to the 9th, 10th, 11th, and 12th furnaces of the smelting furnace. In this way, four furnaces are one round. In the figure, 1+ represents the first use of the first furnace refining slag after the first recycling, and 1++ represents the second use of the first furnace refining slag after the second recycling.

[0043] If the production process of cold heading steel includes converter smelting, refining, vacuum furnace smelting and continuous casting four processes, the refining slag recycling mode is: the 1st, 2nd, 3rd, 4th and 5th furnace of the converter smelting furnace (initial furnace) is the new slag making process, and the slag produced after the 1st, 2nd, 3rd, 4th and 5th furnace of the smelting furnace is added to the 6th, 7th, 8th, 9th and 10th furnace of the smelting furnace respectively. Similarly, the slag produced after the 6th, 7th, 8th, 9th and 10th furnace of the smelting furnace is added to the 11th, 12th, 13th, 14th and 15th furnace of the smelting furnace respectively. In this way, the process is repeated every 5 furnaces.

[0044] Each production enterprise can adjust and set the circulating furnace of the refining slag recycling mode according to the production process and production rhythm.

[0045] (3) Difficulties and solutions of refining slag recycling

[0046] ① The problem of sufficient sulfur capacity in refining slag needs to be solved in the process of repeated use of refining slag:

[0047] With the increase of the recycling times of refining slag, the sulfur capacity in the refining slag will gradually decrease, and finally there will be no desulfurization effect, and the basic function of refining top slag will be lost. To solve this problem, the sulfur capacity of the refining slag can be increased by adding slag.

[0048] For CaO-SiO2-Al2O3 slag system, supplement the slag at the converter tapping, the slag includes lime and calcium aluminate, the addition amount of the two is respectively:

[0049] Lime addition amount = lime amount of new slag (initial furnace) * 0.5 + (lime amount of new slag / 6 - lime amount of new slag / 3)

[0050] Calcium aluminate addition amount = calcium aluminate amount of new slag * 0.5 - (calcium aluminate of new slag / 6 - calcium aluminate amount of new slag / 3)

[0051] Note: The amount of lime and fluorite added in the refining process should be less than or equal to 200 kg and 100 kg respectively according to the submerged arc effect.

[0052] ② The stability problem of the total amount of refining slag:

[0053] With the increase of the recycling times of refining slag, the production of deoxidation products and the continuous addition of refining slag will lead to the gradual increase of the amount of slag, and the excessive amount of refining slag will affect the control of the tapping amount and increase the manufacturing cost. Therefore, by discharging part of the top slag and supplementing the above slag, the total amount of refining slag can be controlled within a relatively stable weight range.

[0054] The discharge of part of the top slag adopts the method of timing ladle turning, and the amount of refining slag in the ladle is stably discharged into the slag basin, which is 1 / 3-1 / 2 of the amount of refining slag in the ladle. The target pouring amount is 1 / 3.

[0055] The control scheme of the timing ladle turning is as follows: the ladle is controlled to move to the slag basin to ensure that the slag can be turned into the slag basin, the auxiliary hook is operated, and when the red slag flows out of the ladle, the auxiliary hook is operated twice again and kept in this state for 8-10s, so that the refined slag in the ladle can be stably controlled to be discharged by 1 / 3-1 / 2.

[0056] ③Stability of the composition of the refining slag

[0057] The composition of the refining slag is the basic guarantee of the refining effect, determines the desulfurization rate of the slag, the modification of the inclusions, the melting point of the slag, the fluidity and a series of properties of the slag, and is very important for the refining of the molten steel, so the stability of the composition of the refining slag needs to be ensured, that is, the basic consistency of the discharge amount and the addition amount needs to be ensured.

[0058] From the perspective of the stability of the on-site control and combined with multiple tests, for the steel grade with high quality requirement, the initial casting residual amount of the ladle is stably controlled through the display of the ladle weighing device (the specific control process is the prior art); for the steel grade with general quality requirement, in addition to the display of the ladle weighing device, the operator closes the slide at the bottom of the ladle when the slag appears in the ladle, so as to stably control the initial casting residual amount of the ladle. The quality requirement is divided according to the steel grade, and the specific division table is the prior art.

[0059] On the basis of the stability of the initial casting residual amount, the operation of the ladle turning is controlled by time, so as to ensure the stability of the composition of the refining slag.

[0060] ④Flexibility and consistency of the process execution:

[0061] The production on site is complex and changeable, and various problems may occur in the production organization process, which may cause the production organization control rhythm to be tense, and the refining slag recovery work to be blocked or interrupted. Through the above slag discharge and slag addition operations, the weight and composition of the casting residual slag received by each furnace of steel can be ensured to be basically consistent, the operator does not need to pay too much attention to whether the furnace is receiving the first round of refining slag, and the converter alloy worker only needs to confirm whether the refining slag needs to be recovered before tapping, and decides the addition amount of the top slag material according to whether the refining slag is recovered (that is, if the refining slag is not recovered, the amount of lime and calcium aluminate is added according to the conventional production process, and if the refining slag is recovered, the amount of lime and calcium aluminate in the supplementary slag material is added), and if one furnace is interrupted, only this furnace needs to be adjusted, which does not affect the stability of the control of the subsequent furnace.

[0062] (4) The converter slag material is added in the tapping process to ensure the slag material to be penetrated.

[0063] (5) The state of the bottom blowing of the molten steel is ensured to be slightly fluctuated to prevent the slag surface from being crusty.

[0064] The cold heading steel refining slag recycling method has the following advantages in the implementation process:

[0065] 1) Through the method, the refining slag components can be stably controlled in the control range of CaO: 52-55%, SiO2: 4-6.5%, AL2O3: 27-33%, and the slag binary basicity is 8-11, and the inclusions in the steel can be controlled in A≤1.5 level, B≤1.5 level, C≤1.5 level, D≤1.5 level, DS≤1.5 level, meeting the quality control requirements of high-end cold heading steel;

[0066] 2) The method can greatly reduce the consumption of slag-making materials and the output of single-day refining slag, improve the yield of molten steel, and according to the calculation of the company of the inventor, the output of single-day refining slag is reduced by about 36.5 tons, and the yield of molten steel is increased by about 24 tons;

[0067] 3) The number of slag pots is reduced, and the manpower and material resources for slag pot and steel slag treatment are reduced, and at present, the company of the inventor reduces about 3 rotating slag pots per day;

[0068] 4) The utilization of hot molten slag greatly improves the slag melting effect in the early stage of refining, increases the submerged arc effect, and reduces the power consumption of refining per ton of steel by about 3.6 Kwh / t;

[0069] 5) The S removal rate in the early stage of refining is obviously improved, the stability of the slag meets the smelting requirements, and the binary basicity fluctuation range is about target basicity±1.2;

[0070] 6) The method is beneficial to the reduction of slag pot transportation cost, steel slag treatment cost, the reduction of the influence of steel slag on the environment, and the reduction of emissions.

[0071] The embodiments are preferred embodiments of the present application, but the present application is not limited to the above embodiments, and any obvious improvement, replacement or modification made by those skilled in the art without departing from the essential content of the present application shall fall within the protection scope of the present application.

Claims

1. A cold upsetting steel refining slag recycling method, characterized in that: the slag produced by continuous casting is added to the refining process for recycling; in the recycling process, new slag is produced from the first ladle of the first converter blowing, and the slag produced by the first ladle of continuous casting is added to the first ladle of the second converter blowing, the slag produced by the second ladle of continuous casting is added to the first ladle of the third converter blowing, and so on until the nth ladle of the Nth converter blowing, n ladles constitute a round, and there are N rounds in total; the slag of the first ladle of the first round is added to the first ladle of the second round for further processing, the slag produced by the first ladle of the second round is added to the first ladle of the third round for further processing, and so on until the first ladle of the Nth round; in the recycling process, the decrease of sulfur capacity during recycling is avoided by adding slag; in the recycling process, the total amount of refining slag is controlled within a stable weight range by discharging part of the top slag and adding slag; the discharging of part of the top slag is carried out by timing ladle turning method, and 1 / 3-1 / 2 of the refining slag in the ladle is discharged into the slag basin stably; in the recycling process, the initial casting residue is stable, and the composition stability of the refining slag is ensured by the timing ladle turning operation of the ladle, and the initial casting residue is stable by the indication of the ladle weighing device. If the cold upsetting steel production process includes converter smelting, refining, and continuous casting, the refining slag recycling mode is: the 1st, 2nd, 3rd, and 4th furnaces of the converter smelting furnace are new slag production processes, the slag produced by the 1st, 2nd, 3rd, and 4th furnaces of the smelting furnace after refining and continuous casting is added to the 5th, 6th, 7th, and 8th furnaces of the smelting furnace, respectively, similarly, the slag produced by the 5th, 6th, 7th, and 8th furnaces of the smelting furnace after refining and continuous casting is added to the 9th, 10th, 11th, and 12th furnaces of the smelting furnace, respectively, and so on. If the cold upsetting steel production process includes converter smelting, refining, vacuum furnace smelting, and continuous casting, the refining slag recycling mode is: the 1st, 2nd, 3rd, 4th, and 5th furnaces of the converter smelting furnace are new slag production processes, the slag produced by the 1st, 2nd, 3rd, 4th, and 5th furnaces of the smelting furnace after refining and continuous casting is added to the 6th, 7th, 8th, 9th, and 10th furnaces of the smelting furnace, respectively, similarly, the slag produced by the 6th, 7th, 8th, 9th, and 10th furnaces of the smelting furnace after refining and continuous casting is added to the 11th, 12th, 13th, 14th, and 15th furnaces of the smelting furnace, respectively, and so on. For CaO-SiO2-Al2O3 slag system, add slag at the time of converter tapping, and the slag includes lime and calcium aluminate. The timing ladle turning method is: the ladle is controlled by the crane to the slag basin range to ensure that the slag can be turned into the slag basin, the auxiliary hook is jogged, and when the red slag flows out of the ladle, the auxiliary hook is jogged twice and kept in this state for 8-10 seconds. In the recycling process, the amount of top slag added is determined by whether the furnace needs to recycle the refining slag to ensure the flexibility and consistency of the process: if not, the amount of lime and calcium aluminate added is the same as that in the conventional production process, and if yes, the amount of lime and calcium aluminate added is the same as that in the supplementary slag. ​ 2. The cold heading steel refining slag recycling method according to claim 1, characterized by, ​ 3. The cold heading steel refining slag recycling method according to claim 1, characterized by, ​ 4. The cold heading steel refining slag recycling method according to claim 1, characterized by, ​ 5. The cold heading steel refining slag recycling method according to claim 1, characterized by, ​ 6. The cold heading steel refining slag recycling method according to claim 4, characterized by, ​

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