Method for smelting and removing arsenic from arsenic-containing molten steel

Abstract

The invention relates to a smelting arsenic removal method for arsenic-containing molten steel, and belongs to the technical field of molten steel smelting. The method comprises the following steps: smelting arsenic-containing molten steel in stages to obtain to-be-arsenic-removed molten steel with target oxygen content and target sulfur content; and the molten steel to be subjected to arsenic removal is subjected to arsenic removal through calcium alloy, and the molten steel subjected to arsenic removal is obtained. According to the embodiment of the invention, O and S are reduced to extremely low levels, conditions are created for improving the arsenic removal efficiency, the arsenic removal efficiency is fully improved, and the arsenic element content of the arsenic-removed molten steel can be controlled to be less than or equal to 0.0020%.

Description

Technical Field

[0001] The present application relates to the technical field of molten steel smelting, and in particular to a method for smelting and removing arsenic from arsenic-containing molten steel. Background Art

[0002] In recent years, the steel industry has increased scrap recycling and the utilization of arsenic-containing ores, leading to the enrichment of arsenic (As) in steel. Arsenic is a harmful element in steel, and excessive levels can easily cause segregation, affecting the steel's toughness and weldability. Industries such as oil production, nuclear power, and food processing all have strict requirements for arsenic content.

[0003] At present, the main idea of ​​arsenic removal in the steel smelting process is to use calcium to remove arsenic from the molten steel. Existing arsenic removal methods mainly include two categories: (1) using alkaline slag systems for arsenic removal, such as CaC2-CaF2 and CaO-CaF2 slag systems. (2) using Ca-Fe and Ca-Si alloys, CaO-Li2O solvents, etc. to carry out arsenic removal after refining. However, in actual production, it is found that the slag steel reaction efficiency of arsenic removal using alkaline slag systems is low, and the consumption of arsenic removal alloys using calcium alloys is large and the cost is high. Summary of the Invention

[0004] The present application provides a method for smelting and removing arsenic from arsenic-containing molten steel to solve the following technical problem: how to improve the efficiency of smelting and removing arsenic from arsenic-containing molten steel.

[0005] In a first aspect, an embodiment of the present application provides a method for smelting and removing arsenic from arsenic-containing molten steel, the method comprising:

[0006] smelting the arsenic-containing molten steel in stages to obtain molten steel to be dearsenified with target oxygen content and target sulfur content;

[0007] The molten steel to be dearsenified is dearsenified using a calcium alloy to obtain the dearsenified molten steel.

[0008] Optionally, the target oxygen content is ≤0.001%.

[0009] Optionally, the target sulfur content is ≤0.0008%.

[0010] Optionally, the amount of the calcium alloy used is ≥0.5 kg / ton of steel.

[0011] Optionally, the staged smelting includes converter smelting, LF refining and VD refining in sequence.

[0012] Optionally, the converter smelting includes a smelting stage and a tapping stage in sequence; wherein,

[0013] The smelting stage includes lime smelting. The chemical composition of the lime includes, by mass fraction, CaO: ≥95%, SiO2: ≤2%, and the amount of lime used is 5kg / ton steel to 10kg / ton steel;

[0014] The tapping stage includes a slag blocking operation so that the slag discharge amount is ≤5kg / ton of steel;

[0015] The terminal oxygen content in the steel tapping stage is ≤550 ppm.

[0016] Optionally, the LF refining is performed using refined slag, and the basicity of the refined slag is 15-25.

[0017] Optionally, the chemical composition of the refined slag includes, by mass fraction: CaO: 50% to 60%, SiO2: ≤3%, Al2O3: 15% to 30%, MgO: 3% to 8%, and CaF2: ≤5%.

[0018] Optionally, the Als content at the endpoint of LF refining is ≥0.06%.

[0019] Optionally, the process parameters of the VD refining include: vacuum degree of <67 Pa, time of ≥13 min, and argon blowing volume of ≥120 NL / min.

[0020] Optionally, the arsenic content of the dearsenicized steel liquid is ≤0.002%.

[0021] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0022] The method for smelting and de-arsenicizing arsenic-containing molten steel provided in an embodiment of the present application, wherein the arsenic content of the arsenic-containing molten steel is ≤0.005%, and the method comprises: smelting the arsenic-containing molten steel in stages to obtain a molten steel to be de-arsenicized having a target oxygen content and a target sulfur content; and de-arsenicizing the molten steel to be de-arsenicized using a calcium alloy to obtain a de-arsenicized molten steel. Arsenic cannot be oxidized in steel and basically exists in a single substance state. Calcium is the most effective element for de-arsenicization, and the calcium-arsenic reaction is an exothermic reaction, and low temperature is conducive to de-arsenicization. However, after calcium is added to the steel, it first reacts with O and S, inhibiting the calcium-arsenic reaction. Therefore, the arsenic-containing molten steel is smelted in stages to obtain a molten steel to be de-arsenicized having a target oxygen content and a target sulfur content. The temperature of the molten steel to be de-arsenicized after the staged smelting is low, the cleanliness of the molten steel is high, and it has the target oxygen content and the target sulfur content, which creates favorable conditions for de-arsenicization and achieves high-efficiency de-arsenicization. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1 A schematic flow chart of a method for smelting and removing arsenic from arsenic-containing molten steel provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0028] In this application, unless otherwise indicated, directional terms such as "upper" and "lower" refer specifically to directions in the drawings. Furthermore, in the description of this application, the terms "include," "comprising," and the like mean "including but not limited to." In this document, relational terms such as "first" and "second" are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0029] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0030] At present, the main idea of ​​arsenic removal in the steel smelting process is to use calcium to remove arsenic from the molten steel. The existing arsenic removal methods mainly include two categories: (1) using alkaline slag system for arsenic removal, such as CaC2-CaF2 and CaO-CaF2 slag system. (2) using Ca-Fe and Ca-Si alloys, CaO-Li2O solvents and other methods to carry out arsenic removal treatment after refining. However, in actual production, it is found that the slag steel reaction efficiency of arsenic removal using alkaline slag system is low, and the consumption of arsenic removal alloy using calcium alloy is large and the cost is high. The applicant found that the slag alkalinity of the smelting process is 8-12, and the molten steel contains high oxygen and sulfur elements, which causes the calcium in the slag and alloy to react preferentially with oxygen and sulfur, inhibiting the arsenic removal reaction. Therefore, before arsenic removal, the oxygen and sulfur content in the molten steel must be controlled at an extremely low level to ensure a high slag alkalinity.

[0031] In a first aspect, the present invention provides a method for removing arsenic from arsenic-containing molten steel. Figure 1 This is a flow chart of a method for smelting and removing arsenic from arsenic-containing molten steel provided in an embodiment of the present application; see Figure 1 , the method comprising:

[0032] S1, smelting the arsenic-containing molten steel in stages to obtain the arsenic-removed molten steel with target oxygen content and target sulfur content;

[0033] Arsenic cannot be oxidized in steel and exists primarily in a single elemental state. Calcium is the most effective element for arsenic removal, and the calcium-arsenic reaction is exothermic, favoring arsenic removal at low temperatures. However, upon addition to steel, calcium first reacts with oxygen and sulfur, inhibiting the calcium-arsenic reaction. Therefore, arsenic removal requires reducing oxygen and sulfur to extremely low levels, thereby obtaining a molten steel with the target oxygen and sulfur contents. The temperature of the molten steel to be dearsenicized after staged smelting is lower, and the steel is highly clean. Through staged smelting, the composition and temperature of the steel can be gradually controlled. Different process measures are implemented at different stages. For example, preliminary deoxidation and desulfurization operations may be performed in the early stages to reduce the oxygen and sulfur contents in the steel, creating conditions for subsequent arsenic removal. Lower temperatures favor the exothermic calcium-arsenic reaction, while higher steel cleanliness reduces interference from other impurities in the dearsenicization reaction. The arsenic content of the arsenic-containing steel can be ≤0.005% by mass.

[0034] In some embodiments, the target oxygen content is ≤ 0.001% by mass.

[0035] In some embodiments, the target sulfur content is ≤ 0.0008% by mass.

[0036] According to formula (1), when the temperature of the molten steel is 1500-1600℃, the Ca element dissolved in the molten steel can react chemically with O, S and As, and the reaction order is O, S, As. Therefore, in order to remove As from the molten steel, the content of O and S should be controlled at the lowest level to promote the de-arsenicization reaction. The calculation results show that when the content of O and S elements in the molten steel is ≤0.001% and ≤0.008% respectively, it is conducive to the de-As reaction. For example, the target oxygen content can be 0.001%, 0.0009%, 0.0008%, 0.0007%, 0.0006%, etc.; the target sulfur content can be 0.0008%, 0.0007%, 0.0006%, 0.0005%, etc.

[0037]

[0038] In some embodiments, the staged smelting includes converter smelting, LF refining and VD refining in sequence.

[0039] The staged smelting may include converter smelting, LF refining and VD refining in sequence, which can be used in synergy to obtain the molten steel to be dearsenified with target oxygen content and target sulfur content.

[0040] In some embodiments, the converter smelting includes a smelting stage and a tapping stage in sequence; wherein,

[0041] The smelting stage includes lime smelting. The chemical composition of the lime includes, by mass fraction, CaO: ≥95%, SiO2: ≤2%, and the amount of lime used is 5kg / ton steel to 10kg / ton steel;

[0042] The tapping stage includes a slag blocking operation so that the slag discharge amount is ≤5kg / ton of steel;

[0043] The terminal oxygen content in the steel tapping stage is ≤550 ppm.

[0044] The CaO content in the lime is ≥95%, and the SiO2 content is ≤2%, which ensures the alkalinity of the slag and creates good desulfurization conditions. The amount of lime used is 5kg / ton steel to 10kg / ton steel, which ensures the amount of slag for converter smelting and accommodates more desulfurization products and deoxidation products. The tapping stage includes a slag blocking operation. The tapping process can use an infrared slide to block the slag, so that the slag volume (the amount of slag entering the ladle from the converter during the converter tapping process) can be ≤5kg / ton steel, which is beneficial for controlling the terminal oxygen content of the molten steel in the converter smelting. The terminal oxygen content of the tapping stage can be ≤550ppm, ensuring the final deoxidation effect of the converter smelting. Illustratively, the CaO content in the lime can be 95%, 96%, 97%, 98%, etc.; the SiO2 content can be 2%, 1.8%, 1.6%, 1.4%, etc.; the amount of lime used can be 5kg / ton steel, 6kg / ton steel, 7kg / ton steel, 8kg / ton steel, 9kg / ton steel, 10kg / ton steel, etc.; the slag amount can be 5kg / ton steel, 4.8kg / ton steel, 4.6kg / ton steel, 4.4kg / ton steel, 4.2kg / ton steel, etc.; the final oxygen content at the steel tapping stage can be 550ppm, 540ppm, 530ppm, 520ppm, 510ppm, 500ppm, etc.

[0045] In some embodiments, the LF refining is performed using refined slag, and the basicity of the refined slag is 15-25.

[0046] The basicity of the refined slag can be 15 to 25 to achieve a good desulfurization effect. For example, the basicity of the refined slag can be 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, etc.

[0047] In some embodiments, the chemical composition of the refined slag includes, by mass fraction, CaO: 50% to 60%, SiO2: ≤3%, Al2O3: 15% to 30%, MgO: 3% to 8%, and CaF2: ≤5%.

[0048] The chemical composition of the refined slag can include: CaO: 50% to 60%, SiO2: ≤3%, Al2O3: 15% to 30%, MgO: 3% to 8%, CaF2: ≤5%, fully achieving the basicity control of the refined slag while regulating the melting point and viscosity of the steel slag. For example, the CaO can be 50%, 52%, 54%, 56%, 58%, 60%, etc.; SiO2 can be 3%, 2.5%, 2.3%, etc.; Al2O3 can be 15%, 17%, 19%, 21%, 23%, 25%, 27%, 29%, 30%, etc.; MgO can be 3%, 4%, 5%, 6%, 7%, 8%, etc.; and CaF2 can be 5%, 4%, 3%, etc.

[0049] In some embodiments, the process parameters of the VD refining include: vacuum degree <67 Pa, time ≥13 min, and argon blowing volume ≥120 NL / min.

[0050] VD refining process parameters can include a vacuum level of <67 Pa, a time of ≥13 minutes, and an argon purge rate of ≥120 NL / min, to achieve oxygen content of ≤0.001% and sulfur content of ≤0.0008% in the molten steel after VD refining. For example, the vacuum level can be 66 Pa, 65 Pa, 64 Pa, etc.; the time can be 13 minutes, 14 minutes, 15 minutes, 16 minutes, etc.; and the argon purge rate can be 120 NL / min, 125 NL / min, 130 NL / min, 135 NL / min, etc. The VD refining cycle is ≥20 minutes (the cycle is the time from the moment the molten steel enters a specific processing equipment (such as a VD refining furnace) to the completion of all predetermined processing operations and preparation for the next step).

[0051] In some embodiments, the endpoint Als content of the LF refining is ≥0.06%.

[0052] The Als content at the end point of LF refining can be ≥0.06% to achieve a good deoxidation effect. For example, the Als content at the end point of LF refining can be 0.06%, 0.05%, 0.04%, etc.

[0053] S2. Dearsenicizing the molten steel to be dearsenified using a calcium alloy to obtain dearsenicized molten steel.

[0054] After the staged smelting process, the oxygen and sulfur content in the molten steel is reduced to the target level. At this point, the addition of calcium alloy allows the calcium to react more with arsenic, forming stable calcium-arsenic compounds. These compounds can then float to the slag, thereby removing arsenic from the molten steel.

[0055] In some embodiments, the amount of the calcium alloy is ≥0.5 kg / ton of steel.

[0056] Based on thermodynamic calculations of arsenic removal, the required calcium content for arsenic removal can be determined by adding a calcium alloy at the end of VD refining. The amount of calcium alloy used can be ≥ 0.5 kg / ton of steel to effectively remove arsenic and achieve an arsenic content of ≤ 0.0020%. For example, the amount of calcium alloy used can be 0.5 kg / ton of steel, 0.4 kg / ton of steel, 0.3 kg / ton of steel, etc.

[0057] The method for smelting and removing arsenic from arsenic-containing molten steel provided in the embodiments of the present application has the following advantages:

[0058] 1. Staged smelting reduces the oxygen and sulfur content in the molten steel, reduces the chance of calcium reacting with oxygen and sulfur, enables calcium to react with arsenic more effectively, and improves arsenic removal efficiency.

[0059] 2. The temperature of the molten steel after staged smelting is relatively low, which meets the thermodynamic conditions of the calcium-arsenic exothermic reaction, is conducive to the forward reaction, and further improves the arsenic removal effect.

[0060] 3. The cleanliness of the molten steel is improved by smelting in stages, and the presence of other impurities is reduced, which is not only beneficial to the dearsenicization reaction, but also improves the quality of the final dearsenicized molten steel.

[0061] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0062] Example 1

[0063] The steel grade smelted is X70, and the production process is 200-ton converter + LF furnace + VD furnace.

[0064] 1) The lime added during the converter smelting process has a CaO content of 95.5%, an SiO2 content of 0.3%, and a lime addition rate of 5.5 kg / ton of steel. During the tapping process, an infrared slide block is used to block the slag, controlling the slag flow rate to 4.5 kg / ton of steel. The oxygen content in the molten steel is 0.04%, and the arsenic content is 0.0026%.

[0065] 2) LF refining process slag formation, the basicity of the refined slag is 25; the mass content of the refined slag is: CaO%: 55%, SiO2%: 2.2%, Al2O3%: 24%, MgO%: 6.2%, CaF2%: 3.0%. The Al2O3 content in the molten steel at the end of LF is 0.068%;

[0066] 3) The molten steel was subjected to VD refining, with a vacuum degree of <67 Pa maintained for 15 minutes and a treatment cycle of 22 minutes; the argon blowing rate for VD refining was 180 NL / min; the oxygen content of the molten steel after VD refining was 0.0008%, and the sulfur content was 0.0004%; calcium iron alloy was added after VD refining, with an addition amount of 0.8 kg / ton of steel.

[0067] 4) The arsenic content in the molten steel after smelting is 0.00177%.

[0068] Example 2

[0069] The steel grade smelted is Q345, and the production process is 200-ton converter + LF furnace + VD furnace.

[0070] 1) The lime added during the converter smelting process has a CaO content of 96% and a SiO2 content of 0.5%, with an addition rate of 6 kg / ton of steel. During the tapping process, an infrared slide block is used to block the slag, controlling the slag flow to 5 kg / ton of steel. The oxygen content in the molten steel is 0.05%, and the arsenic content is 0.0029%.

[0071] 2) LF refining process slag formation, the basicity of the refined slag is 21; the mass content of the refined slag is: CaO%: 56%, SiO2%: 2.6%, Al2O3%: 25%, MgO%: 6%, CaF2%: 4.2%. The Al2O3 content in the molten steel at the end of LF is 0.064%;

[0072] 3) The molten steel was subjected to VD refining, with a vacuum degree of <67 Pa maintained for 14 minutes and a treatment cycle of 22 minutes; the argon blowing rate for VD refining was 150 NL / min; the oxygen content of the molten steel after VD refining was 0.001%, and the sulfur content was 0.0005%; calcium iron alloy was added after VD refining, with an addition amount of 1.0 kg / ton of steel.

[0073] 4) The arsenic content in the molten steel after smelting is 0.00167%.

[0074] Example 3

[0075] The steel grade smelted is A514, and the production process is 200-ton converter + LF furnace + VD furnace.

[0076] 1) The lime added during the converter smelting process contained 96.5% CaO and 0.34% SiO2, with an addition rate of 5.8 kg / ton of steel. During the tapping process, an infrared slide was used to block the slag, controlling the slag rate to 5 kg / ton of steel. The oxygen content of the molten steel was 0.048%, and the arsenic content was 0.0026%.

[0077] 2) LF refining process slag formation, the basicity of the refined slag is 19; the mass content of the refined slag is: CaO%: 52%, SiO2%: 2.7%, Al2O3%: 23%, MgO%: 7.2%, CaF2%: 3.8%. The Al2O3 content in the molten steel at the end of LF is 0.072%;

[0078] 3) The molten steel was subjected to VD refining, with a vacuum degree of <67 Pa maintained for 13 minutes and a treatment cycle of 20 minutes; the argon blowing rate for VD refining was 160 NL / min; the oxygen content of the molten steel after VD refining was 0.0009%, and the sulfur content was 0.0005%; calcium iron alloy was added after VD refining, with an addition amount of 0.9 kg / ton of steel.

[0079] 4) The arsenic content in the molten steel after smelting is 0.00182%.

[0080] Comparative Example 1

[0081] The steel grade smelted is X70, and the production process is 200-ton converter + LF furnace + VD furnace.

[0082] 1) The lime added during the converter smelting process has a CaO content of 95.5%, an SiO2 content of 0.3%, and a lime addition rate of 5.5 kg / ton of steel. During the tapping process, an infrared slide block is used to block the slag, controlling the slag flow rate to 4.5 kg / ton of steel. The oxygen content in the molten steel is 0.04%, and the arsenic content is 0.0027%.

[0083] 2) LF refining process slag formation, the basicity of the refined slag is 25; the mass content of the refined slag is: CaO%: 55%, SiO2%: 2.2%, Al2O3%: 24%, MgO%: 6.2%, CaF2%: 3.0%. The Al2O3 content in the molten steel at the end of LF is 0.068%;

[0084] 3) The molten steel is subjected to VD refining, with a vacuum degree of <67 Pa maintained for 15 minutes and a treatment cycle of 22 minutes; the argon blowing rate for VD refining is 180 NL / min; the oxygen content of the molten steel after VD refining is 0.0008%, and the sulfur content is 0.0004%; no calcium iron alloy is added after VD refining.

[0085] 4) The arsenic content in the molten steel after smelting is 0.00277%.

[0086] Comparative Example 2

[0087] The steel grade smelted is X70, and the production process is 200-ton converter + LF furnace + VD furnace.

[0088] 1) The lime added during the converter smelting process has a CaO content of 92.5%, an SiO2 content of 2.0%, and a lime addition rate of 5.5 kg / ton of steel. During the tapping process, an infrared slide block is used to block the slag, controlling the slag flow rate to 4.5 kg / ton of steel. The oxygen content in the molten steel is 0.04%, and the arsenic content is 0.0026%.

[0089] 2) LF refining process slag formation, the basicity of the refined slag is 10; the weight content of the refined slag is: CaO%: 55%, SiO2%: 2.5%, Al2O3%: 25%, MgO%: 6.4%, CaF2%: 2.2%. The AlS content in the molten steel at the end of LF refining is 0.028% (aluminum addition is insufficient; aluminum is added after tapping from the converter and at the beginning of LF refining).

[0090] 3) The molten steel was subjected to VD refining, with a vacuum degree of <67 Pa maintained for 15 minutes and a treatment cycle of 22 minutes; the argon blowing rate for VD refining was 180 NL / min; the oxygen content of the molten steel after VD refining was 0.0014%, and the sulfur content was 0.008%; calcium iron alloy was added after VD refining, with an addition amount of 0.8 kg / ton of steel.

[0091] 4) The arsenic content in the molten steel after smelting is 0.00256%.

[0092] Comparative Example 3

[0093] The steel grade smelted is A514, and the production process is 200-ton converter + LF furnace + VD furnace.

[0094] 1) The lime added during the converter smelting process contained 96.5% CaO and 0.34% SiO2, with an addition rate of 5.8 kg / ton of steel. During the tapping process, an infrared slide was used to block the slag, controlling the slag rate to 5 kg / ton of steel. The oxygen content of the molten steel was 0.048%, and the arsenic content was 0.0022%.

[0095] 2) LF refining process slag formation, the basicity of the refined slag is 9; the mass content of the refined slag is: CaO%: 52%, SiO2%: 5.8%, Al2O3%: 23%, MgO%: 7.2%, CaF2%: 3.8%. The Al2O3 content in the molten steel at the end of LF is 0.072%;

[0096] 3) The molten steel was subjected to VD refining, with a vacuum degree of <67 Pa maintained for 13 minutes and a treatment cycle of 20 minutes; the argon blowing rate for VD refining was 160 NL / min; the oxygen content of the molten steel after VD refining was 0.0009%, and the sulfur content was 0.0015%; calcium iron alloy was added after VD refining, with an addition amount of 0.9 kg / ton of steel.

[0097] 4) The arsenic content in the molten steel after smelting is 0.0022%.

[0098] From the above examples 1-3 and comparative examples 1-3, it can be seen that examples 1-3 can control the arsenic content in arsenic-containing molten steel to ≤ 0.0020%. However, in comparative example 1, no calcium alloy was added, and in comparative example 2, insufficient aluminum was added during the smelting of the molten steel, resulting in a low Als content in the molten steel after LF. Furthermore, the basicity of the refined slag in comparative example 3 was low, which, to a certain extent, resulted in an arsenic content in the molten steel exceeding 0.0020% after smelting.

[0099] One or more technical solutions in the embodiments of the present application may have at least the following technical effects or advantages:

[0100] (1) The slag volume and high aluminum content are effectively deoxidized under the control of the converter process. At the same time, high-efficiency bottom blowing technology is adopted in the LF-VD process. The O content in the molten steel is ≤0.0010%. High-quality lime is used to control the slag basicity in the refining process to 15-25. The S content in the molten steel is stably controlled at ≤0.0008%, creating good thermodynamic and kinetic conditions for arsenic removal from the molten steel.

[0101] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for removing arsenic from arsenic-containing molten steel, comprising: smelting the arsenic-containing molten steel in stages to obtain molten steel to be dearsenified with target oxygen content and target sulfur content; The molten steel to be dearsenified is dearsenified using a calcium alloy to obtain the dearsenified molten steel.

2. The method according to claim 1, characterized in that The target oxygen content is ≤ 0.001%.

3. The method according to claim 1 or 2, characterized in that The target sulfur content is ≤ 0.0008%.

4. The method according to claim 1, wherein The amount of the calcium alloy is ≥0.5 kg / ton of steel.

5. The method according to claim 1, characterized in that The staged smelting includes converter smelting, LF refining and VD refining in sequence.

6. The method according to claim 5, characterized in that The converter smelting includes the smelting stage and the steel tapping stage in sequence; wherein, The smelting stage includes lime smelting. The chemical composition of the lime includes, by mass fraction, CaO: ≥95%, SiO2: ≤2%, and the amount of lime used is 5kg / ton steel to 10kg / ton steel; The tapping stage includes a slag blocking operation so that the slag discharge amount is ≤5kg / ton of steel; The terminal oxygen content in the steel tapping stage is ≤550 ppm.

7. The method according to claim 5, characterized in that The LF refining is performed using refined slag, and the basicity of the refined slag is 15-25.

8. The method according to claim 7, characterized in that Calculated by mass fraction, the chemical composition of the refined slag includes: CaO: 50% to 60%, SiO2: ≤3%, Al2O3: 15% to 30%, MgO: 3% to 8%, and CaF2: ≤5%.

9. The method according to claim 5, characterized in that The Als content at the end point of LF refining is ≥0.06%.

10. The method according to claim 5, characterized in that The process parameters of the VD refining include: vacuum degree <67 Pa, time ≥13 min, and argon blowing volume ≥120 NL / min.

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