Method for synergistically preparing iron-chromium-nickel alloy by using stainless steel electric furnace refining dust and blast furnace dedusting ash

Abstract

The invention belongs to the technical field of collaborative comprehensive utilization of metallurgical solid waste resources, and particularly relates to a method for collaborative preparation of an iron-chromium-nickel alloy from stainless steel electric furnace refining dust and blast furnace dedusting ash. The method comprises the following steps: uniformly mixing raw materials, and carrying out cold press molding, high-temperature carbon thermal reduction and cooling to obtain a mixture of the iron-chromium-nickel alloy and the self-pulverization slag. According to the method, the solid waste electric furnace refining dust, the blast furnace fly ash and the coking coal with the relatively low adding amount serve as raw materials, the iron-chromium-nickel alloy with the high metal grade is obtained through the high-temperature carbon thermal reduction technology, and due to the synergistic reduction effect of the blast furnace fly ash and the solid waste electric furnace refining dust, the reduction efficiency of the whole preparation process is greatly improved; and no flux is added, efficient separation of the reduction product alloy particles and the self-pulverization slag can be achieved by cooling to the room temperature in the inert atmosphere, and energy consumption and production cost are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of coordinated comprehensive utilization of metallurgical solid waste resources, and specifically relates to a method for collaboratively preparing iron-chromium-nickel alloy by utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash. Background Art

[0002] Stainless steel, a foundational material in modern industry, is widely used in fields such as construction, automotive, aerospace, and medical devices. The smelting and processing of stainless steel produces large amounts of heavy metal dust, accounting for approximately 1.5-3.0% of the total output. This dust contains significant amounts of heavy metal elements such as iron, chromium, and nickel, as well as dioxins. If not promptly treated and simply dumped or landfilled, heavy metals can migrate into soil and water bodies through leachate. Carcinogens such as Cr are more likely to accumulate through the food chain, threatening human health. Promptly treating this solid waste dust can reduce environmental pollution, lower production raw material costs, and reduce the pressure of imports. Therefore, how to efficiently recover the metal resources from stainless steel dust produced during electric furnace refining and develop lower-cost processes to reduce energy costs while also minimizing environmental pollution are currently crucial research issues. Blast furnace ironmaking, a core process in the modern steel industry, generates large amounts of dust, a key issue in solid waste management. Every ton of crude steel produced generates approximately 15-30 kg of blast furnace dust. This dust contains heavy metals such as Zn and Pb, as well as leachable fluoride (F-). If simply stored or landfilled, the mobility of Zn and Pb can reach 30-50% under acidic precipitation conditions, posing a long-term threat to groundwater and surrounding ecosystems. Blast furnace dust is also an energy source, with Fe and C contents comparable to a mixture of low-grade iron ore and anthracite. Efficient recycling can replace some raw materials and reduce energy consumption in ironmaking. For example, if a steel plant with an annual pig iron production capacity of 10 million tons could fully recycle blast furnace dust for sintering, it could save 300,000 tons of iron concentrate, 80,000 tons of coke, and reduce CO2 emissions by approximately 200,000 tons annually. Reusing this solid waste resource would yield both resource and economic benefits. Currently, there are many methods for treating electric furnace refining dust and blast furnace dust, but these methods often have the following problems: (1) Most methods require energy in the process of preparing reaction raw materials and are accompanied by the emission of waste gas, etc. The raw material preparation process is complicated and consumes a lot of heat energy. (2) Some methods require the addition of nearly half or more coking coal, which consumes a large amount of coking coal and is not conducive to the development of energy conservation and emission reduction. (3) Some methods use electric furnace refining dust or blast furnace dust to prepare ferroalloys, but their metal recovery rate is low and the metal grade in the alloy is low.

[0003] Therefore, there is still a need for a new method for synergistically preparing iron-chromium-nickel alloy by utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash to improve the metal grade of Ni, Cr and Fe in the prepared nickel-chromium-iron alloy, reduce the energy consumption of resource processing and reduce CO2 emissions during the processing process, and improve the utilization rate of metallurgical solid waste. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing iron-chromium-nickel alloy using stainless steel electric furnace refining dust and blast furnace dust ash, by combining the mutual utilization and synergistic reduction of solid wastes to achieve cost reduction, efficiency improvement, resource conservation, environmental protection and emission reduction, so as to improve the metal grade of Ni, Cr and Fe in the prepared nickel-chromium-iron alloy, reduce the energy consumption of resource processing and reduce the emission of CO2 during the processing process, and improve the utilization rate of solid waste.

[0005] In order to solve the above technical problems, and considering that the iron, chromium, and nickel oxides in the electric furnace refined stainless steel dust need to be reduced to metals, and the blast furnace dust contains a large amount of carbon elements, which can provide a part of the reducing agent, and the blast furnace dust also contains recyclable iron oxides, the concept of this invention is to mix the two solid waste products of electric furnace refined stainless steel dust and blast furnace dust ash and treat them simultaneously, using the carbon resources contained in the blast furnace dust to reduce the metal oxides in the electric furnace refined stainless steel dust, which can simultaneously recover the metal resources of the two solid waste products, and can also reduce the amount of external coking coal added, thereby achieving the reduction of metal elements while reducing economic costs. Therefore, the present invention provides a method for collaboratively preparing iron-chromium-nickel alloy using stainless steel electric furnace refined dust and blast furnace dust, the method comprising:

[0006] Step 1) mixing electric furnace refining dust, blast furnace dust, coking coal, a binder, and water uniformly, and then cold pressing to obtain a mixed briquette;

[0007] Step 2) subjecting the mixed compact obtained in step 1) to high-temperature carbothermal reduction;

[0008] Step 3) Cooling the high-temperature carbon thermal reduction product obtained in step 2) to room temperature under the protection of an inert gas to obtain a mixture of an iron-chromium-nickel alloy and self-pulverizing slag;

[0009] The above method for preparing the iron-chromium-nickel alloy does not use a flux and does not require a heat source during the cold forming stage.

[0010] In step 1), electric furnace refining dust, blast furnace dust removal ash, coking coal, binder and water are uniformly mixed and then cold-pressed into a mold. There is no need for high-temperature heating to produce greenhouse gases, and no wet leaching to produce wastewater, which further reduces energy consumption and alleviates environmental pressure.

[0011] In step 1), the binder may be a binder commonly used by those skilled in the art, such as bentonite or a composite binder.

[0012] In the above-mentioned method of preparing iron-chromium-nickel alloy by collaboratively utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash, the method for separating the mixture of iron-chromium-nickel alloy and self-pulverizing slag can be: sorting magnetic material and non-magnetic material, the magnetic material is iron-chromium-nickel alloy, and the non-magnetic material is self-pulverizing slag.

[0013] Only with an appropriate carbon content can metal oxides be reduced, and only with an appropriate basicity can the reduction products be separated. In order to achieve a metal recovery rate of over 90% for Fe, over 89% for Cr, and over 91% for Ni in the overall electric furnace refining dust and blast furnace dust, as a preferred embodiment, in the above-mentioned method for synergistically preparing an iron-chromium-nickel alloy using stainless steel electric furnace refining dust and blast furnace dust, the mass ratio of electric furnace refining dust to blast furnace dust is (60-70):(30-40); the content of coking coal is 5-10% of the total mass of the electric furnace refining dust and blast furnace dust; the content of binder is 4-6% of the total mass of the electric furnace refining dust and blast furnace dust; and the content of water is 6-8% of the total mass of the electric furnace refining dust and blast furnace dust.

[0014] As a preferred solution, the electric furnace refining dust meets at least one of the following conditions:

[0015] The total iron mass fraction is not less than 31%;

[0016] The chromium mass fraction is not less than 8%;

[0017] The nickel mass fraction is not less than 2%.

[0018] The advantage of stainless steel electric furnace refining dust meeting at least one of the above conditions is that it can achieve a high recovery rate of reduction products and a high recycling value.

[0019] As a preferred solution, the blast furnace dust ash meets at least one of the following conditions:

[0020] The total iron content is not less than 29%;

[0021] The carbon mass fraction is not less than 20%.

[0022] The benefits of blast furnace dust that meets at least one of the above conditions are that it can achieve a high recovery rate of reduced products and high recycling value. The high carbon content can provide a reducing agent, reduce the proportion of coking coal, and reduce the amount of coking coal used.

[0023] As a preferred solution, the coking coal meets at least one of the following conditions:

[0024] The fixed carbon mass fraction is not less than 60%;

[0025] Ash content not higher than 10%;

[0026] Volatile matter does not exceed 30%;

[0027] The colloid layer index is not less than 12mm.

[0028] Among them, coking coal has a high carbon content and can provide more reducing agents, which is beneficial to subsequent reduction.

[0029] As a preferred solution, the electric furnace refined dust is obtained by at least one of drying, crushing, and screening through a 200-mesh sieve.

[0030] As a preferred solution, the blast furnace dust ash is obtained by at least one of drying, crushing, and screening through a 200-mesh sieve.

[0031] As a preferred solution, the coking coal is obtained by at least one of drying, crushing, and screening through a 200-mesh sieve.

[0032] As a preferred solution, the binder is obtained by at least one of drying, crushing, and screening through a 200-mesh sieve.

[0033] As a preferred embodiment, in step 3) of the method for preparing an iron-chromium-nickel alloy using stainless steel electric furnace refining dust and blast furnace dust removal ash, the cooling rate under inert gas protection is 23-28°C / min. This is because controlling the cooling rate appropriately facilitates the pulverization and separation of the reduction product, thereby increasing the yield of the iron-chromium-nickel alloy. Furthermore, cooling under an inert atmosphere prevents oxidation of the reduction product.

[0034] Ensuring a certain pressure and time ensures that the raw materials are fully in contact, and the prepared mixed briquettes have a certain strength to meet the requirements of subsequent reduction. As a preferred embodiment, in step 1) of the above-mentioned method of using stainless steel electric furnace refining dust and blast furnace dust to synergistically prepare iron-chromium-nickel alloy, the operating conditions of the cold pressing meet at least one of the following conditions:

[0035] Cold pressing pressure is 25-45MPa;

[0036] The holding time is 0.5-4min.

[0037] As a preferred embodiment, in step 2) of the above-mentioned method for preparing an iron-chromium-nickel alloy by synergistically utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash, the operating conditions of the high-temperature carbothermal reduction meet at least one of the following conditions:

[0038] The temperature of high-temperature carbothermal reduction is 1350-1500℃;

[0039] The time for high-temperature carbothermal reduction is 25-55 min;

[0040] The CO2 partial pressure of high-temperature carbothermal reduction does not exceed 10%.

[0041] Controlling the CO2 gas partial pressure to no more than 10% can ensure the CO gas partial pressure and ensure the provision of a reducing atmosphere.

[0042] As a preferred embodiment, step 2) of the above method of using stainless steel electric furnace refining dust and blast furnace dust to collaboratively prepare iron-chromium-nickel alloy is carried out under the protection of inert gas.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] The present invention provides a method for synergistically preparing an iron-chromium-nickel alloy using stainless steel electric furnace refining dust and blast furnace dust ash. The method uses solid waste electric furnace refining dust, blast furnace dust ash, and relatively low-addition coking coal as raw materials, and obtains an iron-chromium-nickel alloy with a high metal grade through a high-temperature carbon thermal reduction process. Due to the synergistic reduction effect of the blast furnace dust ash and solid waste electric furnace refining dust, the reduction efficiency of the entire preparation process is greatly improved. Without adding any flux, the reduction product alloy particles and self-pulverizing slag can be efficiently separated by cooling to room temperature in an inert atmosphere, thereby reducing energy consumption and production costs. Furthermore, the method provided by the present invention synergistically preparing an iron-chromium-nickel alloy using stainless steel electric furnace refining dust and blast furnace dust ash uses a relatively small amount of coking coal, generates less volatile matter and ash during the reduction process, and has relatively low environmental pollution. Furthermore, the self-pulverizing slag produced does not contain metals such as Ni, Cr, and Fe, further reducing environmental pollution. At the same time, the method provided by the present invention for preparing iron-chromium-nickel alloy using electric furnace refining dust and blast furnace dust removal ash has a simple process flow and low requirements for process conditions such as reaction temperature. It can save resources, protect the environment and reduce emissions, and has high economic benefits, and has broad industrial application prospects.

[0045] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The present invention is a process flow chart of a specific embodiment of a method for collaboratively preparing iron-chromium-nickel alloy by utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash. DETAILED DESCRIPTION

[0047] In the following description, exemplary embodiments according to the present invention will be described in more detail. However, these exemplary embodiments can be implemented in a variety of different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided to make the disclosure of the present invention thorough and complete and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art.

[0048] In the examples and comparative examples of the present invention, the electric furnace refining dust was sourced from a domestic stainless steel manufacturer; the blast furnace dust was sourced from a domestic stainless steel manufacturer; and the coking coal was sourced from a domestic stainless steel manufacturer. The binder was bentonite. The total iron content of the electric furnace refining dust was no less than 31% by mass; the chromium content was no less than 8% by mass; and the nickel content was no less than 2% by mass. The total iron content of the blast furnace dust was no less than 29% by mass; and the carbon content was no less than 20% by mass. The coking coal had a fixed carbon content of no less than 60% by mass; an ash content no greater than 10%; a volatile matter content no greater than 30%; and a colloidal layer index of no less than 12 mm.

[0049] In the embodiments and comparative examples of the present invention, separation of magnetic material and non-magnetic material refers to separation of a mixture of iron-chromium-nickel alloy and self-pulverizing slag by magnetic adsorption, wherein the magnetic material is the iron-chromium-nickel alloy and the non-magnetic material is the self-pulverizing slag.

[0050] In the examples and comparative examples of the present invention, the inert gas used is argon.

[0051] Example 1

[0052] This embodiment provides a method for preparing an iron-chromium-nickel alloy by collaboratively utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash.

[0053] Figure 1 The process flow chart of a specific embodiment of the present invention shows a method for preparing an iron-chromium-nickel alloy by synergistically utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash. Figure 1 The separation method here refers to the separation of magnetic and non-magnetic materials. Figure 1 :

[0054] The electric furnace refined dust, blast furnace dust, coking coal, and binder are fully dried, crushed, sieved through a 200-mesh sieve, and evenly mixed with water. The mixture is then pressed under a cold press pressure of 30 MPa and a holding time of 1 minute to obtain mixed briquettes. The mass ratio of electric furnace refined dust, blast furnace dust, coking coal, binder, and water is 60:40:10:6:8.

[0055] The crucible containing the mixed compacts is placed in a high-temperature furnace and, under a non-oxidizing atmosphere, undergoes a high-temperature carbon thermal reduction and cooling process. After cooling to room temperature, magnetic and non-magnetic materials are separated to obtain an iron-chromium-nickel alloy and harmless self-pulverizing slag. The high-temperature reduction temperature is 1400°C, the reduction time is 40 minutes, and the cooling rate is 25°C / min. The resulting high-grade iron-chromium-nickel alloy contains 62% by mass of metal Fe, 13% by mass of metal Cr, and 4% by mass of metal Ni. The mass fractions of the harmful components P and S are both less than 0.05%, and the proportion of particles less than 74μm (below 200 mesh) in the self-pulverizing slag reaches more than 70%. The metal recovery rates of Fe, Cr, and Ni in the overall electric furnace refining dust and blast furnace dust removal ash are 91%, 90%, and 92%, respectively.

[0056] Example 2

[0057] This embodiment provides a method for preparing an iron-chromium-nickel alloy by collaboratively utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash.

[0058] The electric furnace refined dust, blast furnace dust, coking coal, and binder are fully dried, crushed, sieved through a 200-mesh sieve, and evenly mixed with water. The mixture is then pressed under a cold press pressure of 35 MPa and a holding time of 1 minute to obtain mixed briquettes. The mass ratio of electric furnace refined dust, blast furnace dust, coking coal, binder, and water is 70:30:5:5:6.

[0059] The crucible containing the mixed compacts is placed in a high-temperature furnace and, under a non-oxidizing atmosphere, undergoes a high-temperature carbon thermal reduction and cooling process. After cooling to room temperature, magnetic and non-magnetic materials are separated to obtain an iron-chromium-nickel alloy and harmless self-pulverizing slag. The high-temperature reduction temperature is 1450°C, the reduction time is 45 minutes, and the cooling rate is 25°C / min. The resulting high-grade iron-chromium-nickel alloy contains 60% by mass of metal Fe, 12% by mass of metal Cr, and 4% by mass of metal Ni. The mass fractions of the harmful components P and S are both less than 0.05%, and the proportion of particles less than 74μm (below 200 mesh) in the self-pulverizing slag reaches more than 70%. The metal recovery rates of Fe, Cr, and Ni in the overall electric furnace refining dust and blast furnace dust removal ash are 90%, 90%, and 91%, respectively.

[0060] Example 3

[0061] This embodiment provides a method for preparing an iron-chromium-nickel alloy by collaboratively utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash.

[0062] The electric furnace refined dust, blast furnace dust, coking coal, and binder are fully dried, crushed, sieved through a 200-mesh sieve, and evenly mixed with water. The mixture is then pressed under a cold press pressure of 40 MPa and a holding time of 1 minute to obtain mixed briquettes. The mass ratio of electric furnace refined dust, blast furnace dust, coking coal, binder, and water is 65:35:5:4:7.

[0063] The crucible containing the mixed compacts is placed in a high-temperature furnace and, under a non-oxidizing atmosphere, undergoes a high-temperature carbon thermal reduction and cooling process. After cooling to room temperature, magnetic and non-magnetic materials are separated to obtain an iron-chromium-nickel alloy and harmless self-pulverizing slag. The high-temperature reduction temperature is 1350°C, the reduction time is 50 minutes, and the cooling rate is 25°C / min. The resulting high-grade iron-chromium-nickel alloy contains 58% by mass of metal Fe, 12% by mass of metal Cr, and 4% by mass of metal Ni. The mass fractions of the harmful components P and S are both less than 0.05%, and the proportion of particles with a size less than 74μm (below 200 mesh) in the self-pulverizing slag reaches more than 70%. The metal recovery rates of Fe, Cr, and Ni in the overall electric furnace refining dust and blast furnace dust removal ash are 90%, 89%, and 91%, respectively.

[0064] Example 4

[0065] This embodiment provides a method for preparing an iron-chromium-nickel alloy by collaboratively utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash.

[0066] The electric furnace refined dust, blast furnace dust, coking coal, and binder are fully dried, crushed, sieved through a 200-mesh sieve, and evenly mixed with water. The mixture is then pressed under a cold press pressure of 25 MPa and a holding time of 4 minutes to obtain mixed briquettes. The mass ratio of electric furnace refined dust, blast furnace dust, coking coal, binder, and water is 65:35:6:5:6.

[0067] The crucible containing the mixed briquette is placed in a high-temperature furnace and, under a non-oxidizing atmosphere, undergoes a high-temperature carbon thermal reduction and cooling process. After cooling to room temperature, magnetic and non-magnetic materials are separated to obtain an iron-chromium-nickel alloy and harmless self-pulverizing slag. The high-temperature reduction temperature is 1500°C, the reduction time is 55 minutes, and the cooling rate is 25°C / min. The obtained high-grade iron-chromium-nickel alloy has a metal Fe mass fraction of 59%, a metal Cr mass fraction of 12%, and a metal Ni mass fraction of 4%. The mass fractions of the harmful components P and S are both less than 0.05%, and the proportion of particles less than 74μm (below 200 mesh) in the self-pulverizing slag reaches more than 70%. The metal recovery rates of Fe, Cr, and Ni in the overall electric furnace refining dust and blast furnace dust removal ash are 91%, 89%, and 91%, respectively.

[0068] Example 5

[0069] This embodiment provides a method for preparing an iron-chromium-nickel alloy by collaboratively utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash.

[0070] The electric furnace refined dust, blast furnace dust, coking coal, and binder are thoroughly dried, crushed, sieved through a 200-mesh sieve, and evenly mixed with water. The mixture is then pressed under a cold press pressure of 40 MPa and a holding time of 2 minutes to obtain a mixed briquette. The mass ratio of electric furnace refined dust, blast furnace dust, coking coal, binder, and water is 70:30:7:5:7.

[0071] The crucible containing the mixed compacts is placed in a high-temperature furnace and, under a non-oxidizing atmosphere, undergoes a high-temperature carbon thermal reduction and cooling process. After cooling to room temperature, magnetic and non-magnetic materials are separated to obtain an iron-chromium-nickel alloy and harmless self-pulverizing slag. The high-temperature reduction temperature is 1400°C, the reduction time is 30 minutes, and the cooling rate is 23°C / min. The resulting high-grade iron-chromium-nickel alloy contains 60% by mass of metal Fe, 12% by mass of metal Cr, and 5% by mass of metal Ni. The mass fractions of the harmful components P and S are both less than 0.05%, and the proportion of particles less than 74μm (below 200 mesh) in the self-pulverizing slag reaches more than 70%. The metal recovery rates of Fe, Cr, and Ni in the overall electric furnace refining dust and blast furnace dust removal ash are 91%, 90%, and 92%, respectively.

[0072] Comparative Example 1

[0073] The difference from Example 1 is that blast furnace dust is not used, and the mass ratio of electric furnace refined dust to coking coal is 100:10.

[0074] The electric furnace refined dust, coking coal, and binder are fully dried, crushed, sieved through a 200-mesh sieve, and evenly mixed with water. The mixture is then pressed under a cold press pressure of 30 MPa and a holding time of 1 minute to obtain a mixed briquette. The mass ratio of electric furnace refined dust, coking coal, binder, and water is 100:10:6:8.

[0075] The crucible containing the mixed compacts was placed in a high-temperature furnace and, under a non-oxidizing atmosphere, subjected to a high-temperature carbon thermal reduction and cooling process. After cooling to room temperature, magnetic and non-magnetic materials were separated to obtain an iron-chromium-nickel alloy and harmless self-pulverizing slag. The high-temperature reduction temperature was 1400°C, the reduction time was 40 minutes, and the cooling rate was 25°C / min. The resulting reduction products could not be separated, and the reduced slag phase did not self-pulverize. The metal recovery rates of Fe, Cr, and Ni in the overall electric furnace refining dust and blast furnace dust removal ash were 85%, 82%, and 87%, respectively.

[0076] Comparative Example 2

[0077] The difference from Example 2 is that the mass ratio of electric furnace refining dust to blast furnace dust is 85:15.

[0078] The electric furnace refined dust, blast furnace dust, coking coal, and binder are fully dried, crushed, sieved through a 200-mesh sieve, and evenly mixed with water. The mixture is then pressed under a cold press pressure of 35 MPa and a holding time of 1 minute to form a mixed briquette. The mass ratio of electric furnace refined dust, blast furnace dust, coking coal, binder, and water is 85:15:5:5:6.

[0079] The crucible containing the mixed compacts is placed in a high-temperature furnace and, under a non-oxidizing atmosphere, undergoes a high-temperature carbon thermal reduction and cooling process. After cooling to room temperature, magnetic and non-magnetic materials are separated to obtain an iron-chromium-nickel alloy and harmless self-pulverizing slag. The high-temperature reduction temperature is 1450°C, the reduction time is 45 minutes, and the cooling rate is 25°C / min. The obtained high-grade iron-chromium-nickel alloy has a metal Fe mass fraction of 58%, a metal Cr mass fraction of 11%, and a metal Ni mass fraction of 4%. The mass fractions of the harmful components P and S are both less than 0.05%, and the proportion of particles less than 74μm (below 200 mesh) in the self-pulverizing slag reaches more than 50%. The metal recovery rates of Fe, Cr, and Ni in the overall electric furnace refining dust and blast furnace dust removal ash are 89%, 88%, and 90%, respectively.

[0080] Comparative Example 3

[0081] The difference from Example 3 is that the mass ratio of electric furnace refining dust, blast furnace dust ash, coking coal, binder and water is 65:35:4:3:5.

[0082] The electric furnace refining dust, blast furnace dust, coking coal and binder are fully dried, crushed, sieved through a 200-mesh sieve, mixed evenly with water, and then pressed under a cold pressing pressure of 40 MPa and a holding time of 1 minute to obtain a mixed briquette.

[0083] The crucible containing the mixed compacts is placed in a high-temperature furnace and, under a non-oxidizing atmosphere, undergoes a high-temperature carbon thermal reduction and cooling process. After cooling to room temperature, magnetic and non-magnetic materials are separated to obtain an iron-chromium-nickel alloy and harmless self-pulverizing slag. The high-temperature reduction temperature is 1350°C, the reduction time is 50 minutes, and the cooling rate is 25°C / min. The resulting high-grade iron-chromium-nickel alloy has a metal Fe mass fraction of 55%, a metal Cr mass fraction of 10%, and a metal Ni mass fraction of 3%. The mass fractions of the harmful components P and S are both less than 0.05%, and the proportion of particles less than 74μm (below 200 mesh) in the self-pulverizing slag reaches more than 65%. The metal recovery rates of Fe, Cr, and Ni in the overall electric furnace refining dust and blast furnace dust removal ash are 88%, 86%, and 90%, respectively.

[0084] Comparative Example 4

[0085] The difference from Example 4 is that the cooling rate under the protection of inert gas is 15° C. / min.

[0086] The electric furnace refined dust, blast furnace dust, coking coal, and binder are fully dried, crushed, sieved through a 200-mesh sieve, and evenly mixed with water. The mixture is then pressed under a cold press pressure of 25 MPa and a holding time of 4 minutes to obtain mixed briquettes. The mass ratio of electric furnace refined dust, blast furnace dust, coking coal, binder, and water is 65:35:6:5:6.

[0087] The crucible containing the mixed compacts was placed in a high-temperature furnace and subjected to a high-temperature carbon thermal reduction and cooling process in a non-oxidizing atmosphere. After cooling to room temperature, the magnetic and non-magnetic materials were separated to obtain an iron-chromium-nickel alloy and harmless self-pulverizing slag. The high-temperature reduction temperature was 1500°C, the reduction time was 55 minutes, and the cooling rate was 15°C / min. The resulting high-grade iron-chromium-nickel alloy contained 60% Fe by mass, 13% Cr by mass, and 4% Ni by mass. The mass fractions of the harmful components P and S were both less than 0.05%, and the proportion of particles less than 74μm (below 200 mesh) in the self-pulverizing slag reached more than 75%. The metal recovery rates of Fe, Cr, and Ni in the overall electric furnace refining dust and blast furnace dust removal ash were 92%, 90%, and 91%, respectively.

[0088] Although comparative example 4 also achieved a relatively high metal recovery rate, the energy consumption was too high due to the long cooling time, making the recovery meaningless.

[0089] Comparative Example 5

[0090] The difference from Example 5 is that the cooling rate under the protection of inert gas is 30° C. / min.

[0091] The electric furnace refined dust, blast furnace dust, coking coal, and binder are thoroughly dried, crushed, sieved through a 200-mesh sieve, and evenly mixed with water. The mixture is then pressed under a cold press pressure of 40 MPa and a holding time of 2 minutes to obtain a mixed briquette. The mass ratio of electric furnace refined dust, blast furnace dust, coking coal, binder, and water is 70:30:7:5:7.

[0092] The crucible containing the mixed compacts is placed in a high-temperature furnace and, under a non-oxidizing atmosphere, undergoes a high-temperature carbon thermal reduction and cooling process. After cooling to room temperature, magnetic and non-magnetic materials are separated to obtain an iron-chromium-nickel alloy and harmless self-pulverizing slag. The high-temperature reduction temperature is 1400°C, the reduction time is 30 minutes, and the cooling rate is 30°C / min. The resulting high-grade iron-chromium-nickel alloy contains 57% by mass of metal Fe, 12% by mass of metal Cr, and 4% by mass of metal Ni. The mass fractions of the harmful components P and S are both less than 0.05%, and the proportion of particles less than 74μm (below 200 mesh) in the self-pulverizing slag reaches more than 55%. The metal recovery rates of Fe, Cr, and Ni in the overall electric furnace refining dust and blast furnace dust removal ash are 90%, 89%, and 90%, respectively.

[0093] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing an iron-chromium-nickel alloy by synergistically utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash, characterized in that: The method includes: Step 1) mixing electric furnace refining dust, blast furnace dust, coking coal, a binder, and water uniformly, and then cold pressing to obtain a mixed briquette; Step 2) subjecting the mixed compact obtained in step 1) to high-temperature carbothermal reduction; Step 3) Cooling the high-temperature carbon thermal reduction product obtained in step 2) to room temperature under the protection of an inert gas to obtain a mixture of an iron-chromium-nickel alloy and self-pulverizing slag; The above method for preparing the iron-chromium-nickel alloy does not use a flux and does not require a heat source during the cold forming stage.

2. The method for preparing an iron-chromium-nickel alloy by synergistically utilizing stainless steel electric furnace refining dust and blast furnace dust according to claim 1, characterized in that: Also includes: Step 4) Separating the mixture of the iron-chromium-nickel alloy and the self-pulverizing slag: separating the magnetic material and the non-magnetic material, wherein the magnetic material is the iron-chromium-nickel alloy and the non-magnetic material is the self-pulverizing slag.

3. The method for preparing an iron-chromium-nickel alloy by synergistically utilizing stainless steel electric furnace refining dust and blast furnace dust according to claim 1, characterized in that: The mass ratio of electric furnace refining dust to blast furnace dust is (60-70): (30-40); The content of coking coal is 5-10% of the total mass of electric furnace refining dust and blast furnace dust; The content of the binder is 4-6% of the total mass of the electric furnace refining dust and blast furnace dust; The water content is 6-8% of the total mass of the electric furnace refining dust and the blast furnace dust.

4. The method for preparing an iron-chromium-nickel alloy by synergistically utilizing stainless steel electric furnace refining dust and blast furnace dust according to claim 1, characterized in that: The electric furnace refining dust meets at least one of the following conditions: The total iron mass fraction is not less than 31%; The chromium mass fraction is not less than 8%; The nickel mass fraction is not less than 2%.

5. The method for preparing iron-chromium-nickel alloy by using stainless steel electric furnace refining dust and blast furnace dust as claimed in claim 1, characterized in that: The blast furnace dust ash meets at least one of the following conditions: The total iron content is not less than 29%; The carbon mass fraction is not less than 20%.

6. The method for preparing an iron-chromium-nickel alloy by synergistically utilizing stainless steel electric furnace refining dust and blast furnace dust according to claim 1, characterized in that: The coking coal meets at least one of the following conditions: The fixed carbon mass fraction is not less than 60%; Ash content not higher than 10%; Volatile matter does not exceed 30%; The colloid layer index is not less than 12mm.

7. The method for preparing an iron-chromium-nickel alloy by using stainless steel electric furnace refining dust and blast furnace dust as claimed in claim 1, characterized in that: At least one of the following conditions must be met: The electric furnace refined dust is obtained by at least one of drying, crushing, and screening through a 200-mesh sieve; The blast furnace dust ash is obtained by at least one of drying, crushing, and screening through a 200-mesh sieve; The coking coal is obtained by at least one of drying, crushing, and screening through a 200-mesh sieve; The binder is obtained by at least one of drying, crushing, and screening through a 200-mesh sieve.

8. The method for preparing an iron-chromium-nickel alloy by synergistically utilizing stainless steel electric furnace refining dust and blast furnace dust according to claim 1, characterized in that: In step 3), the cooling rate under the protection of inert gas is 23-28°C / min.

9. The method for preparing an iron-chromium-nickel alloy by synergistically utilizing stainless steel electric furnace refining dust and blast furnace dust according to claim 1, characterized in that: In step 1), the operating conditions of the cold press forming meet at least one of the following conditions: Cold pressing pressure is 25-45MPa; The holding time is 0.5-4min.

10. The method for preparing iron-chromium-nickel alloy by utilizing stainless steel electric furnace refining dust and blast furnace dust removal ash according to claim 1, characterized in that: In step 2), the operating conditions of the high-temperature carbothermal reduction meet at least one of the following conditions: The temperature of high-temperature carbothermal reduction is 1350-1500℃; The time for high-temperature carbothermal reduction is 25-55 min; The CO2 partial pressure of high-temperature carbothermal reduction does not exceed 10%.

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