CN113201620B - Method for smelting sulfur-containing steel grade by using desulphurization slag - Google Patents

Method for smelting sulfur-containing steel grade by using desulphurization slag Download PDF

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CN113201620B
CN113201620B CN202110543363.XA CN202110543363A CN113201620B CN 113201620 B CN113201620 B CN 113201620B CN 202110543363 A CN202110543363 A CN 202110543363A CN 113201620 B CN113201620 B CN 113201620B
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slag
sulfur
tapping
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CN113201620A (en
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汪晛
何兴中
潘建设
黄道昌
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Baowu Group Echeng Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

The invention discloses a utilization stripperThe method for smelting the sulfur-containing steel grade by using the sulfur slag comprises the following steps: (1) adding desulfurized slag to increase sulfur in the converter tapping process: the oxygen content of molten steel is more than or equal to 400ppm in the tapping process, 4-6Kg/t of desulfurized slag is added into a steel ladle in advance before tapping, and 0.030-0.050% wt of S can be recovered; deoxidizing alloy is added when tapping 3/4-tapping is finished; (2) manufacturing low-alkalinity slag in an LF furnace: molten steel enters an LF furnace, lime and rich SiO2The silicon slag is prepared by the following steps of 1: 2, controlling the alkalinity of the slag to be 0.7-1.0; (3) the slag surface deoxidizing materials are reasonably added in the refining process: the FeO of the furnace slag is controlled to be 4-6%, the deoxidizing material adopts Si-based deoxidizing agent SiC, and the strong deoxidizing material is not allowed to be added in the refining process; (4) soft stirring is carried out in the whole refining process, and the ladle bottom blowing ventilation flow is 100 plus 200L/min; the invention effectively utilizes the waste resource desulphurization slag for the second time, can save the lime usage of the slag former of the LF furnace and the sulfur series alloy usage, and simultaneously, the Fe in the desulphurization slag can be directly recovered, thereby improving the yield of the molten steel and having remarkable social and economic benefits.

Description

Method for smelting sulfur-containing steel grade by using desulphurization slag
Technical Field
The invention relates to the technical field of smelting of sulfur-containing steel grades, in particular to a method for smelting sulfur-containing steel grades by using desulfurized slag.
Background
A large amount of desulfurization slag can be generated after the molten iron is desulfurized, and the desulfurization slag is generally discarded due to high sulfur content. Analyzing the components of the desulfurized slag, wherein the desulfurized slag is rich in CaS, the CaS in the desulfurized slag is more than or equal to 5 wt%, and SiO is213 to 18 percent of CaO, 55 to 65 percent of CaO, 0.5 to 1.5 percent of Fe, and the balance of impurity elements. Because the content of S in the desulphurization slag is high and S is a harmful element to conventional steel, the desulphurization slag has extremely low utilization value and is generally discarded for use. However, through the research on the smelting process, sulfur in the desulphurization slag can be replaced by S in an oxidation mode]By optimizing the smelting process, [ S ] can be obtained]Elements stably enter molten steel. Based on this, the desulfurized slag can be recycled and utilized when smelting a specific steel grade such as a sulfur-containing steel.
Disclosure of Invention
The invention aims to provide a method for smelting sulfur-containing steel by using desulfurization slag, aiming at the problems that the desulfurization slag is generally used as waste in the current production process and the reasonable recycling of resources is not achieved.
The invention relates to a method for smelting sulfur-containing steel by using desulfurized slag, which comprises the following steps:
(1) adding desulfurized slag to increase sulfur in the converter tapping process: the method comprises the following steps of (1) completing sulfur increase in the converter tapping process, wherein the oxygen content of molten steel in the tapping process is more than or equal to 400ppm, adding 4-6Kg/t of desulfurization slag into a steel ladle in advance before tapping, and recovering 0.030-0.050% of S; in order to avoid the influence on the recovery rate of S caused by the deoxidation of the added alloy in the tapping process, the deoxidation alloying alloy is added in a delayed manner in the tapping process, and the alloy is added when the tapping is 3/4-the tapping is finished;
(2) manufacturing low-alkalinity slag in an LF furnace: molten steel enters an LF furnace to limit the alkalinity of slag, and lime and SiO are rich2The silicon slag is prepared by the following steps of 1: 2, adding lime in an amount of 2-3Kg/t, adding silica slag in an amount of 4-6 Kg/furnace, and controlling the alkalinity of the slag to be 0.7-1.0;
(3) the slag surface deoxidizing materials are reasonably added in the refining process: the FeO of the slag is controlled to be 4-6%, the deoxidizing material adopts Si series deoxidizer SiC, the adding amount of the SiC of each ton of steel is 0.6-0.8Kg/t, and aluminum series, calcium series and other strong deoxidizing materials are not allowed to be added in the refining process;
(4) soft stirring in the whole refining process: the ladle bottom blowing air flow is 100-200L/min, so that the desulfurization reaction caused by strong stirring is prevented.
CaS in the desulfurization slag is more than or equal to 5 wt%, and SiO is213 to 18 percent of CaO, 55 to 65 percent of CaO, 0.5 to 1.5 percent of Fe, and the balance of impurity elements.
The lime comprises the following components: CaO content 95% wt, SiO2The content is 3 wt%, and the others are impurity elements.
The lime comprises the following components: the silicon slag comprises the following components: SiO 2290 wt% of MgO, 5 wt% of CaO, and the balance of impurity elements.
The SiC components are as follows: the Si content is 78 wt%, the C content is 18 wt%, the Mn content is 2 wt%, and the others are impurity elements.
The method is made after researching the desulfuration residue and the reduction recovery mechanism of S in the desulfuration residue. The desulfurized slag is a product obtained after molten iron is desulfurized, wherein S exists in the form of CaS. The CaS enters the slag to form a stable phase, and the CaS is difficult to be effectively and stably utilized by a common method. Two problems need to be solved for smelting sulfur-containing steel grade by utilizing the desulfurized slag:
(1) solving the problem of recovering S in the desulfurized slag CaS;
(2) how to stabilize S in molten steel after the S is reduced into the molten steel, the conventional process of sulfur-containing steel needs LF treatment, LF has an environment atmosphere with high alkalinity and low FeO, has strong desulfurization capability, and solves the problem that the S is stable in a refining environment after entering the molten steel.
The specific method for solving the two problems is as follows:
(1) the method for recovering S in the desulfurization slag comprises the following steps:
s in the desulfurization slag exists in the form of CaS: according to the slag desulfurization molecular theory, CaS can react with O, and is oxidized to generate [ S ] which enters molten steel, and the reaction formula is as follows:
（CaS）+[O]=（CaO）+[S]
based on the method, the desulphurization slag can be recovered and applied to the CaS in the desulphurization slag by adopting an oxidation reaction mode, the desulphurization slag is added into a steel ladle in the converter tapping process, the [ O ] in the converter tapping process is up to more than 400ppm, the strong stirring dynamic condition in the tapping process is better, and an excellent convenient condition is provided for the [ S ] in the desulphurization slag to be oxidized and enter molten steel.
(2) How to stabilize S in molten steel after S is oxidized into the molten steel, particularly in an LF (ladle furnace) environment:
the desulfurization of the refining furnace generally needs atmosphere with high alkalinity and low FeO content and good dynamic conditions, the treatment conditions of the refining furnace are effectively limited for controlling the desulfurization, the control is carried out from the aspects of slag components, diffusion deoxidation, stirring and the like, and the strong deoxidation in the refining process is avoided, so that the stability of the [ S ] in the molten steel is ensured.
The invention has the beneficial effects that:
(1) the waste resource desulphurization slag is effectively recycled for the second time, and the social benefit and the economic benefit are obvious.
(2) The consumption of lime as a slagging agent of the LF furnace can be saved, and the consumption of chalcogenide alloy can be saved.
(3) The invention has low production cost, can directly recover Fe in the desulphurization slag and improves the yield of the molten steel.
Detailed Description
In order to better explain the technical solution of the present invention, the technical solution of the present invention is further described below with reference to specific examples, which are only exemplary to illustrate the technical solution of the present invention and do not limit the present invention in any way.
Example 1
In the embodiment, the invention is explained in detail by taking the smelting of certain sulfur-containing steel as an example, the standard of the S content of the finished sulfur-containing steel product in the embodiment is 0.050-0.080% wt, and the S content at the smelting end point of the converter is 0.020% wt; the specific operation comprises the following steps:
(1) adding desulfurized slag to increase sulfur in the converter tapping process: the method comprises the following steps of (1) completing sulfur increasing in the converter tapping process, wherein the oxygen content of molten steel in the tapping process is 450ppm, 4Kg/t of desulfurized slag is added into a ladle in advance before tapping, deoxidized alloy is added in the tapping process when the tapping is 3/4, and the sampled S content is 0.051% wt (namely the S content after converter argon);
(2) manufacturing low-alkalinity slag in an LF furnace: molten steel enters an LF furnace to limit the alkalinity of slag, and lime and SiO are rich2The silicon slag is prepared by the following steps of 1: 2, the lime is added in a ratio of 2Kg/t, the silicon slag is added in a ratio of 4 Kg/furnace, and the alkalinity of the slag is 0.7; the lime comprises the following components: CaO content 95% wt, SiO2The content is 3 wt%, and the others are impurity elements; the silicon slag comprises the following components: SiO 2290 wt% of MgO, 5 wt% of CaO, and the balance of impurity elements;
(3) the slag surface deoxidation material is reasonably added in the refining process, the FeO in the slag is 4 percent by weight, the deoxidation material adopts Si-series deoxidizer SiC (the deoxidation product generated by adopting SiC is SiO)2The reduction of the alkalinity of the slag can be promoted when the silicon carbide (SiC) enters the slag), the adding amount of the SiC of each ton of steel is 0.6Kg/t, and aluminum series, calcium series and other strong deoxidizing materials are not allowed to be added in the refining process; the SiC comprises the following components: the Si content is 78 wt%, the C content is 18 wt%, the Mn content is 2 wt%, and the others are impurity elements;
(4) soft stirring in the whole refining process: the ladle bottom blowing air flow is 100L/min, so that the desulfurization reaction caused by strong stirring is prevented; and after refining, sampling, wherein the S content is 0.052 wt%, and the requirement of the sulfur content of the finished steel is met.
In the desulfurization slag of the present example, CaS: 5.8% wt, SiO216.3 wt%, CaO 58 wt%, Fe 1.2 wt%, and others are impurity elements.
And (4) analyzing results: the desulfurization slag is added to increase the sulfur by 0.031 percent wt in the converter tapping process, the S after converter argon is 0.051 percent wt, and the S after refining is 0.052 percent wt. The content of S is controlled stably in the converter-refining process, the fluctuation of the content of S is only 0.001 percent by weight, and the content of 0.052 percent by weight of the refined components meets the component control standard, which shows that the yield of S is stable and controllable when the method is used for smelting the sulfur-containing steel grade.
Example 2
In this example, the invention is explained in detail by taking the smelting of a certain sulfur-containing steel as an example, the standard of S content of the sulfur-containing steel finished product in this example is 0.050-0.080% wt, and the S content at the smelting end point of the converter is 0.030% wt; the specific operation comprises the following steps:
(1) adding desulfurized slag to increase sulfur in the converter tapping process: the method comprises the following steps of (1) completing sulfur increasing in the tapping process, wherein the oxygen content of molten steel in the tapping process is 600ppm, adding 6Kg/t of desulfurized slag into a ladle in advance before tapping, and adding alloy used for deoxidation alloying when tapping is 3/4-tapping is finished; the sampled S content was 0.080% wt (i.e. S content after converter argon);
(2) manufacturing low-alkalinity slag in an LF furnace: molten steel enters an LF furnace to limit the alkalinity of slag, and lime and SiO are rich2The silicon slag is prepared by the following steps of 1: 2, adding lime in an amount of 3Kg/t, adding silicon slag in an amount of 6 Kg/furnace, and controlling the alkalinity of the slag to be 1.0; the lime comprises the following components: CaO content 95% wt, SiO2The content is 3 wt%, the other is impurity elements, and the silicon slag comprises the following components: SiO 2290 wt% of MgO, 5 wt% of CaO, and the balance of impurity elements;
(3) the slag surface deoxidizing materials are reasonably added in the refining process: the FeO of the furnace slag is controlled at 6 percent, the deoxidizing material adopts Si-series deoxidizer SiC (the deoxidizing product generated by adopting SiC is SiO)2The reduction of the slag alkalinity can be promoted when the SiC enters the slag), the adding amount of SiC of each ton of steel is 0.8Kg/t, and aluminum series, calcium series and other strong deoxidizing materials are not allowed to be added in the refining process; the SiC components are as follows: the Si content is 78 wt%, the C content is 18 wt%, the Mn content is 2 wt%, and the others are impurity elements;
(4) the whole refining process is soft stirred, the ladle bottom blowing ventilation flow is 200L/min, the desulfurization reaction caused by strong stirring is prevented, the refining is finished, the sampling is carried out, and the S content is 0.079 percent by weight.
In the desulfurization slag in the present example, the ratio of CaS: 6.5% wt, SiO216.2 wt%, CaO 58 wt%, Fe 0.8 wt%, and others are impurity elements.
And (4) analyzing results: the sulfur content of the added desulfurized slag is 0.050 percent by weight in the converter tapping process, the S content after converter argon is 0.080 percent by weight, and the S content after refining is 0.079 percent by weight. The S content is controlled stably in the converter-refining process, the fluctuation of the S content is only 0.001 percent, and the refining finishing component of 0.080 percent by weight meets the component control standard.
As can be seen from the above examples 1-2, according to the method of the present invention, S is increased during the tapping process of the converter, LF is weakly deoxidized and weakly stirred by adjusting the slag system and the silicon system deoxidizer, and the control of the sulfur-increasing process is stable. After analyzing the results of examples 1 to 2, it was found that: the invention can stably recover the [ S ]. Provides a new feasible method for the production of sulfur-containing steel and the secondary utilization of the desulphurization slag.

Claims (4)

1. A method for smelting sulfur-containing steel by using desulfurized slag is characterized by comprising the following steps:
(1) adding desulfurized slag to increase sulfur in the converter tapping process: the method comprises the following steps of (1) completing sulfur increase in the converter tapping process, wherein the oxygen content of molten steel in the tapping process is more than or equal to 400ppm, adding 4-6Kg/t of desulfurization slag into a steel ladle in advance before tapping, and recovering 0.030-0.050% of S; in order to avoid the influence on the recovery rate of S caused by the deoxidation of the added alloy in the tapping process, the deoxidation alloying alloy is added in a delayed manner in the tapping process, and the alloy is added when the tapping is 3/4-the tapping is finished;
(2) manufacturing low-alkalinity slag in an LF furnace: molten steel enters an LF furnace to limit the alkalinity of slag, and lime and SiO are rich2The silicon slag is prepared by the following steps of 1: 2, adding lime in an amount of 2-3Kg/t, adding silica slag in an amount of 4-6 Kg/furnace, and controlling the alkalinity of the slag to be 0.7-1.0;
(3) the slag surface deoxidizing materials are reasonably added in the refining process: the FeO in the furnace slag is controlled to be 4-6%, the deoxidizing materials adopt Si deoxidizer SiC, the adding amount of SiC per ton steel is 0.6-0.8Kg/t, and aluminum, calcium and other strong deoxidizing materials are not allowed to be added in the refining process;
(4) soft stirring in the whole refining process: the ladle bottom blowing ventilation flow rate is 100-;
CaS in the desulfurization slag is more than or equal to 5 wt%, and SiO is213 to 18 percent of CaO, 55 to 65 percent of CaO, 0.5 to 1.5 percent of Fe, and the balance of impurity elements.
2. The method for smelting sulfur-containing steel grade by using the desulfurized slag according to claim 1, characterized in that: the lime comprises the following components: CaO content 95% wt, SiO2The content is 3 wt%, and the others are impurity elements.
3. The method for smelting sulfur-containing steel grade by using the desulfurized slag according to claim 1, characterized in that: the components of the silicon slag are as follows: SiO 2290 wt% of MgO, 5 wt% of CaO, and the balance of impurity elements.
4. The method for smelting sulfur-containing steel grade by using the desulfurized slag according to claim 1, characterized in that: the SiC components are as follows: the Si content is 78 wt%, the C content is 18 wt%, the Mn content is 2 wt%, and the others are impurity elements.
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CN114737105B (en) * 2022-03-28 2023-05-23 江苏沙钢集团淮钢特钢股份有限公司 Smelting method for producing sulfur-containing steel from low-sulfur molten iron
CN115852090B (en) * 2022-11-15 2023-09-29 安徽工业大学 Method for modifying and recycling metallurgical refining waste residues
CN116579670B (en) * 2023-07-13 2023-10-03 北京工业大学 Economic benefit calculation and feasibility assessment method for recycling thermal refining slag

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