A Fe-Si / CaCO3 material, its preparation method, and its application as a steel refining agent.

Abstract

This invention provides a Fe-Si / CaCO3 material, its preparation method, and its application as a steel refining agent, relating to the field of resource utilization technology. The method for preparing Fe-Si / CaCO3 material from CO2-co-treated waste residue provided by this invention includes the following steps: (1) pressing the waste residue into a mold and fixing it to one end of a metal rod; the waste residue contains iron, silicon, and calcium; (2) immersing the waste residue in molten salt, using the metal rod as the cathode, the molten salt as the electrolyte, and an inert electrode as the anode, and performing molten electrolysis on the waste residue in an atmosphere containing CO2 gas, thereby obtaining Fe-Si / CaCO3 material on the cathode. This invention prepares Fe-Si / CaCO3 powder by co-processing CO2 and waste residue in a one-step molten salt electrolysis method, realizing the green, low-temperature, and carbon-free co-utilization of CO2 and waste residue.

Description

Technical Field

[0001] This invention relates to the field of resource utilization technology, specifically to an Fe-Si / CaCO3 material, its preparation method, and its application as a steel refining agent. Background Technology

[0002] The steel production process generates large amounts of CO2 and steel slag. In 2022, CO2 emissions reached approximately 3.38 billion tons, and the cumulative stockpile of steel slag reached 1.8 billion tons. The utilization of CO2 and steel slag has become a hot and difficult issue. The "dual carbon" target has put forward new requirements for the green and circular development of my country's steel industry.

[0003] Currently, the co-utilization of CO2 with steel slag resources mainly focuses on carbonation and carbon fixation for building materials. Although this method can achieve large-scale utilization of steel slag, the low concentration of free CaO in the steel slag leads to low CO2 utilization. Furthermore, this treatment method cannot extract valuable metals such as Fe and Si from the steel slag or utilize the slag to prepare Fe-Si alloys.

[0004] Currently, typical methods for preparing Fe-Si alloys mainly include carbothermal reduction, powder metallurgy, mechanical alloying, spark plasma sintering, and laser sintering. Most of these methods use Fe and Si metal powders as raw materials and require high-temperature conditions; the carbothermal reduction method can use oxides as raw materials, but this method does not meet the requirements of green and low-carbon development under a dual-carbon background. Summary of the Invention

[0005] The purpose of this invention is to provide a Fe-Si / CaCO3 material, its preparation method, and its application as a steel refining agent. This invention uses CO2 in conjunction with waste slag to prepare Fe-Si / CaCO3 material. The obtained Fe-Si / CaCO3 material can be used as a steel refining agent for clean steel production, which is an important direction for realizing green circularity in the steel industry. It will provide new ideas for green circularity and high-end steel production under the "dual carbon" background, has high scientific research value, and will generate huge social and economic benefits.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing Fe-Si / CaCO3 materials using CO2 and waste residue, comprising the following steps:

[0008] (1) The waste residue is pressed into shape and then fixed to one end of a metal rod; the waste residue contains iron, silicon and calcium.

[0009] (2) The waste residue is soaked in molten salt, the metal rod is used as the cathode, the molten salt is used as the electrolyte, and the inert electrode is used as the anode. The waste residue is molten electrolyzed in an atmosphere containing CO2 gas to obtain Fe-Si / CaCO3 material on the cathode.

[0010] Unlike traditional methods and applications of CO2-co-slag utilization, this invention employs a novel molten salt electrolysis technique to prepare Fe-Si / CaCaO3 materials from CO2-co-slag in a single step. During the molten salt electrolysis process, oxygen is continuously removed from the cathode slag, with some of the oxygen ions reacting with dissolved CO2 to form carbonate ions, while the rest are discharged at the anode as oxygen via the molten salt. The carbonate ions then carbonate with calcium ions at the cathode to form CaCO3. The slag continuously loses oxygen at the cathode and forms an Fe-Si alloy, ultimately yielding the Fe-Si / CaCO3 material as the cathode product.

[0011] This invention involves pressing waste residue into a mold and then fixing it to one end of a metal rod. In this invention, the waste residue contains iron, silicon, and calcium, and is preferably steel slag or red mud. Preferably, the waste residue originates from steel slag converter slag or refining slag; and preferably includes multiple compounds selected from calcium ferrite, calcium silicate, iron oxide, aluminum silicate, calcium aluminosilicate, and calcium ferrosilicate.

[0012] In this invention, the waste residue preferably undergoes high-temperature drying before pressing and molding; the temperature of the high-temperature drying is preferably 200–500°C, more preferably 300–400°C; the time of the high-temperature drying is preferably 6–24 h, more preferably 10–18 h. This invention removes moisture from the waste residue through high-temperature drying. Preferably, after high-temperature drying, the resulting waste residue is cooled and then ball-milled to obtain waste residue powder; the waste residue powder is then pressed and molded. In this invention, the particle size of the waste residue powder is preferably 30–150 μm, more preferably 60–80 μm.

[0013] In this invention, the pressing pressure is preferably 4–12 MPa, more preferably 10 MPa; the temperature is preferably 300–1000 °C, more preferably 400 °C; and the holding time is preferably 15–60 s, more preferably 20–30 s. In this invention, the morphology of the pressed waste residue is preferably a dense block of 1 cm × 1 cm × 2 cm.

[0014] In this invention, the method of fixing the waste residue to one end of the metal rod after pressing and molding is preferably by using a metal wire. In this invention, the metal rod is preferably made of iron, nickel, or copper.

[0015] This invention involves immersing the waste residue in molten salt, using the metal rod as the cathode, the molten salt as the electrolyte, and an inert electrode as the anode. The waste residue is then subjected to molten electrolysis in an atmosphere containing CO2 gas, yielding an Fe-Si / CaCO3 material on the cathode. In this invention, the molten salt is preferably a salt containing one or more of lithium, sodium, potassium, and calcium; more preferably, it is a chloride salt containing one or more of lithium, sodium, potassium, and calcium; specifically, it is preferably one or more of potassium chloride, sodium chloride, lithium chloride, and calcium chloride. In this invention, the inert electrode preferably comprises tin dioxide, a nickel alloy, or graphite sheets. In this invention, the CO2 gas preferably originates from air, emissions from the steel, heating, or coal industries, or gases emitted from the anode during aluminum electrolysis.

[0016] In this invention, the atmosphere containing CO2 gas preferably also includes a protective gas. The purpose of introducing the protective gas is to protect the reaction system from oxygen contamination and to adjust the concentration of CO2 gas. In this invention, the flow rate of the CO2 gas is preferably 5–500 mL / min, more preferably 10–300 mL / min; the protective gas preferably includes argon or nitrogen; the flow rate of the protective gas is preferably 300–1500 mL / min, more preferably 500–1000 mL / min.

[0017] In this invention, the preferred time for molten electrolysis is 0.5–10 h; the preferred voltage is 2–3.3 V, more preferably 2.8–3.2 V; and the preferred temperature of the molten salt during molten electrolysis is 600–900 °C, more preferably 700–850 °C. During the molten electrolysis process, the waste residue is electroreduced at the cathode under CO2 injection to form an Fe-Si alloy. The CO2 reacts with the CaO dissociated from the waste residue to form CaCO3 at the cathode. Partially dissolved CaO in the molten salt and the molten salt itself are carbonated with CO2 to form CaCO3 and other carbonates.

[0018] Preferably, after the molten electrolysis, the cathode is removed, cooled under inert gas protection, cleaned, and then dried to obtain the Fe-Si / CaCO3 material. In this invention, the inert gas is preferably argon; the cleaning solution is preferably deionized water. In this invention, the drying process is preferably carried out in a vacuum drying oven; the drying temperature is preferably 100–300°C, and the drying time is preferably 0.5–3 hours.

[0019] In this invention, the molten salt after molten electrolysis contains carbonates; preferably, the molten salt containing carbonates is cooled, washed with water to separate it, and then dried to recover the carbonates. In this invention, the carbonates preferably include one or more of calcium carbonate, sodium carbonate, lithium carbonate, potassium carbonate, and magnesium carbonate.

[0020] This invention provides an Fe-Si / CaCO3 material prepared by the method described above, comprising Fe-Si alloy and CaCO3. In this invention, the preferred mass ratio of the Fe-Si alloy to CaCO3 is 33–95:5–67, more preferably 33:67.

[0021] In a specific embodiment of the present invention, the Fe-Si alloy includes one or more of Fe3Si and FeSi.

[0022] This invention provides the application of the Fe-Si / CaCO3 material described in the above-mentioned technical solution as a steel refining agent. In response to the new requirements for green and circular development in the steel industry, the co-utilization of CO2 with waste slag and its return to steel production is a new approach to meet these requirements. High-quality and high-end steel products are important directions for the development of my country's steel industry, and quality control in the clean steel production process is a key link in controlling the quality of steel products. Adding refining agents during steelmaking is an important means of clean steel production, and the composition of the refining agent is crucial to the production of clean steel. This invention uses CO2 in synergy with steel slag to prepare Fe-Si / CaCO3 steel refining agents for clean steel production, which is an important direction for realizing green and circular development in the steel industry. It will provide new ideas for green and circular steel production under the "dual carbon" background, has high scientific research value, and will generate significant social and economic benefits. Attached Figure Description

[0023] Figure 1 This is a process flow diagram of the preparation of Fe-Si / CaCO3 steel refining agent using CO2 synergistically with steel slag in an embodiment of the present invention;

[0024] Figure 2 The XRD pattern of the Fe-Si / CaCO3 powder prepared in Example 1;

[0025] Figure 3 The XRD pattern of the Fe-Si / CaCO3 powder prepared in Example 2;

[0026] Figure 4 The image shows the XRD pattern of the Fe-Si / CaCO3 powder prepared in Example 3. Detailed Implementation

[0027] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0028] Example 1

[0029] According to such Figure 1 The process shown employs CO2 in conjunction with steel slag to prepare Fe-Si / CaCO3 steel refining agent:

[0030] 1) Place the steel slag in a ceramic crucible and dry it in a heating furnace at a high temperature of 400℃ for 6 hours;

[0031] 2) Remove the dried steel slag from the ceramic crucible, cool it, and then ball mill it;

[0032] 3) Press 1g of ball-milled steel slag (particle size 60-80μm) into shape (pressure 10MPa, temperature 400℃, holding time 30s) and fix it to one end of a nickel rod with metal wire;

[0033] 4) The steel slag is immersed in molten salt (sodium chloride and calcium chloride in a molar ratio of 1:1), the nickel rod is used as the cathode, the molten salt is used as the electrolyte and the temperature is maintained at 850℃, the inert electrode tin dioxide is used as the anode, and the steel slag is molten electrolyzed for 10h under the condition of a mixed gas with an argon flow rate of 500mL / min and a CO2 flow rate of 20mL / min, and the electrolysis voltage is 2.8V;

[0034] 5) After removing the cathode and cooling it under argon protection, clean it and place it in a vacuum drying oven at 150°C for 1 hour to obtain Fe-Si / CaCO3 powder; after cooling the molten salt containing CaCO3, wash it with water to separate it, and then dry it to recover CaCO3.

[0035] Figure 2 The image shows the XRD pattern of the Fe-Si / CaCO3 powder prepared in Example 1. Figure 2 It can be seen that the main phases in the XRD-detected sample are Fe-Si alloy and CaCO3, with a small amount of Fe and Si metals.

[0036] Example 2

[0037] According to such Figure 1 The process shown employs CO2 in conjunction with steel slag to prepare Fe-Si / CaCO3 steel refining agent:

[0038] 1) Place the steel slag in a ceramic crucible and dry it in a heating furnace at a high temperature of 400℃ for 6 hours;

[0039] 2) Remove the dried steel slag from the ceramic crucible, cool it, and then ball mill it;

[0040] 3) Press 1g of ball-milled steel slag (particle size 60-80μm) into shape (pressure 10MPa, temperature 400℃, holding time 30s) and fix it to one end of a nickel rod with metal wire;

[0041] 4) The steel slag is immersed in molten salt (sodium chloride and calcium chloride in a molar ratio of 1:1), the nickel rod is used as the cathode, the molten salt is used as the electrolyte and the temperature is maintained at 850℃, the inert electrode tin dioxide is used as the anode, and the steel slag is molten electrolyzed for 10h under the condition of a mixed gas with an argon flow rate of 500mL / min and a CO2 flow rate of 20mL / min, and the electrolysis voltage is 3.0V;

[0042] 5) After removing the cathode and cooling it under argon protection, clean it and place it in a vacuum drying oven at 150°C for 1 hour to obtain Fe-Si / CaCO3 powder; after cooling the molten salt containing CaCO3, wash it with water to separate it, and then dry it to recover CaCO3.

[0043] Figure 3 The image shows the XRD pattern of the Fe-Si / CaCO3 powder prepared in Example 2. Figure 3 It can be seen that the main phases in the XRD-detected sample are Fe-Si alloy and CaCO3, with a small amount of Fe and Si metals.

[0044] Example 3

[0045] According to such Figure 1 The process shown employs CO2 in conjunction with steel slag to prepare Fe-Si / CaCO3 steel refining agent:

[0046] 1) Place the steel slag in a ceramic crucible and dry it in a heating furnace at a high temperature of 400℃ for 6 hours;

[0047] 2) Remove the dried steel slag from the ceramic crucible, cool it, and then ball mill it;

[0048] 3) Press 1g of ball-milled steel slag (particle size 60-80μm) into shape (pressure 10MPa, temperature 400℃, holding time 30s) and fix it to one end of a nickel rod with metal wire;

[0049] 4) The steel slag is immersed in molten salt (sodium chloride and calcium chloride in a molar ratio of 1:1), the nickel rod is used as the cathode, the molten salt is used as the electrolyte and the temperature is maintained at 850℃, the inert electrode tin dioxide is used as the anode, and the steel slag is molten electrolyzed for 10h under the condition of a mixed gas with an argon flow rate of 500mL / min and a CO2 flow rate of 20mL / min, and the electrolysis voltage is 3.2V;

[0050] 5) After removing the cathode and cooling it under argon protection, clean it and place it in a vacuum drying oven at 150°C for 1 hour to obtain Fe-Si / CaCO3 powder; after cooling the molten salt containing CaCO3, wash it with water to separate it, and then dry it to recover CaCO3.

[0051] Figure 4The image shows the XRD pattern of the Fe-Si / CaCO3 powder prepared in Example 3. Figure 4 The XRD analysis shows that the sample contains Fe-Si alloy and CaCO3.

[0052] This invention is the first to prepare Fe-Si / CaCO3 powder by co-processing CO2 and steel slag in a one-step molten salt electrolysis method, realizing the green, low-temperature, and carbon-free co-utilization of CO2 and steel slag, and providing a new solution and new ideas for the co-utilization of CO2 and steel slag resources.

[0053] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing Fe-Si / CaCO3 materials using CO2 and waste residue, specifically comprising the following steps: (1) The waste residue is pressed into shape and then fixed to one end of a metal rod; the waste residue contains iron, silicon and calcium. (2) The waste residue is soaked in molten salt, the metal rod is used as the cathode, the molten salt is used as the electrolyte, and the inert electrode is used as the anode. The waste residue is molten electrolyzed in an atmosphere containing CO2 gas to obtain Fe-Si / CaCO3 material on the cathode. The melting electrolysis time is 0.5 to 10 hours, and the voltage is 2 to 3.3 V.

2. The method according to claim 1, characterized in that, The waste residue is steel slag or red mud.

3. The method according to claim 1, characterized in that, The waste residue is further subjected to high-temperature drying before being pressed and molded; the temperature of the high-temperature drying is 200-500℃; and the time of the high-temperature drying is 6-24 hours.

4. The method according to claim 1, characterized in that, The pressing pressure is 4-12 MPa, the temperature is 300-1000℃, and the heat and pressure holding time is 15-60 s.

5. The method according to claim 1, characterized in that, The molten salt is a salt containing one or more of lithium, sodium, potassium and calcium.

6. The method according to claim 1, characterized in that, The inert electrode includes tin dioxide, nickel alloy, or graphite sheet.

7. The method according to claim 1, characterized in that, The atmosphere containing CO2 gas also includes a protective gas.

8. The method according to claim 1, characterized in that, The temperature of the molten salt during the molten electrolysis is 600–900°C.

9. The Fe-Si / CaCO3 material prepared by the method according to any one of claims 1 to 8 comprises Fe-Si alloy and CaCO3.

10. The application of the Fe-Si / CaCO3 material of claim 9 as a steel refining agent.

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