A process for producing low-nickel manganese iron by using nickel-containing smelting waste residue-rich furnace

Abstract

The application discloses a process method for producing low-nickel manganese iron by using nickel-containing smelting waste, and belongs to the technical field of metallurgical solid waste resource utilization and alloy smelting. The method aims to solve the problems of insufficient treatment of nickel-containing smelting waste, low resource recovery rate and difficulty in directional production of high-value-added alloys in the prior art. The technical scheme is characterized in that: first, the nickel-containing smelting waste is mixed with carbonaceous reducing agent, flux and the like to form briquettes and is dried; then, the dry briquettes are pre-reduced in a rotary hearth furnace to obtain hot briquettes with high metallization rate; the key step is to directly hot-charge the hot briquettes into a rich slag furnace, and to use the special double-sided and multi-air duct oxygen-enriched injection technology of the rich slag furnace to perform strong stirring and final reduction and melting separation, and to efficiently recover iron, nickel and manganese elements. The method can convert the difficult-to-treat smelting waste into low-nickel manganese iron alloy with controllable composition, and can be directly used for steelmaking, while realizing zero emission of solid waste.

Description

Technical Field

[0001] This invention relates to the fields of metallurgical solid waste resource utilization and alloy smelting technology, and more specifically, to a process for producing low-nickel manganese ferrometallurgy using nickel-containing smelting waste. Background Technology

[0002] The smelting process of nickel generates a large amount of nickel-containing solid waste, including smelting slag, dust, and sludge. This solid waste typically contains valuable metals such as iron, nickel, copper, and cobalt, and has high recycling value. However, many domestic enterprises currently manage this type of smelting waste in a relatively crude manner, generally using stockpiling or landfill methods. This not only occupies land, but the heavy metals (such as nickel ions) can easily cause secondary pollution of soil and water sources through leachate, posing a high environmental risk. At the same time, this also results in a serious waste of resources.

[0003] To recover these valuable metals, the industry has made various attempts. For example, some technologies use induction furnace melting and powder injection reduction or oxy-coal heating to extract iron, but these suffer from low metal recovery rates (nickel and cobalt recovery rates ≥90%) and high processing costs. Other technologies propose using rotary hearth furnaces to treat laterite nickel ore or nickel-containing solid waste. For instance, patent CN201310559523 proposes a combined process of "rotary hearth furnace reduction-gas furnace melting" to treat nickel smelting slag, which can comprehensively recover valuable elements and achieve zero solid waste emissions. Patent CN117363893A discloses a method for treating nickel-containing solid waste using a rotary hearth furnace, incorporating it as part of the raw material batching, aiming to achieve "solid waste not leaving the factory." However, these methods mostly focus on recovering iron and nickel, or producing nickel-iron alloys. There are no systematic reports on processes that simultaneously and efficiently recover manganese, often associated with waste, and produce low-nickel manganese ferroalloys with controllable composition.

[0004] Furthermore, existing processes for producing ferronickel from laterite nickel ore, such as the rotary kiln-electric furnace (RKEF) process and the rotary hearth furnace process, while technically mature, are primarily designed for raw ore and have limited adaptability to smelting waste with complex and variable compositions. They also generally suffer from high energy consumption, difficulty in recovering associated elements, or long process flows. In the steelmaking industry, producing nickel-containing steel typically requires adding expensive electrolytic nickel or ferronickel alloys to the converter or electric furnace, resulting in high costs.

[0005] Therefore, there is an urgent need to develop a new green metallurgical process that is low-cost, short-process, and highly resource-integrated, capable of turning nickel-containing smelting waste into valuable resources and directly producing high-value-added low-nickel manganese ferroalloys. Summary of the Invention

[0006] The purpose of this invention is to solve the problem of low economic value caused by the low utilization rate of nickel-containing smelting waste. It provides a process for producing low-nickel ferromanganese from nickel-containing smelting waste. Using various nickel-containing smelting wastes as the main raw materials, the invention optimizes the ratio of quenching and tempering raw materials and combines the rotary hearth furnace pre-reduction and rich slag furnace final reduction and melting processes to achieve the production of high-value steelmaking raw material, low-nickel ferromanganese.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A process for producing low-nickel ferromanganese from nickel-containing smelting waste, characterized by comprising the following steps: S1. Raw material pretreatment and batching: The nickel-containing smelting waste is dried, crushed, and screened; according to the mass percentage, 60-85% of the treated nickel-containing smelting waste, 10-25% of carbonaceous reducing agent, 3-10% of flux, and 1-5% of binder are mixed and batched; the nickel-containing smelting waste contains the following mass percentages: TFe 30-50%, Ni 0.5-5.0%, Mn 1.0-8.0%, SiO2 10-25%, CaO 5-15%; S2. Bulk forming and drying: The uniformly mixed ingredients are formed into green pellets or green blanks by a pelletizing machine or a disc pelletizing machine, and then dried at 200-400℃ for 4-8 hours to obtain dry pellets. S3. Rotary hearth furnace pre-reduction: Dry pellets are evenly distributed into a rotary hearth furnace and rapidly reduced in a reducing atmosphere at a temperature range of 1150-1300℃ for 15-40 minutes to obtain hot metallized pellets with a metallization rate ≥85%. S4. Final Reduction and Melting in Rich Slag Furnace: The hot metallized pellets obtained in step S3 are directly charged into the rich slag furnace. Oxygen-enriched air (50%-90% oxygen concentration) is blown into the molten pool through multiple air ducts on both sides of the furnace, intensely and uniformly stirring the slag and the added material mixture. This key technology makes the redox reaction faster and more uniform, significantly improving smelting efficiency, effectively inhibiting iron over-oxidation, and promoting the reduction and enrichment of nickel and manganese oxides into the metallic phase. By controlling the oxygen enrichment rate and fuel supply, the molten pool temperature is precisely controlled at 1500-1650℃, achieving complete slag-iron separation and homogenization of the alloy composition.

[0008] S5. Product output and slag treatment: Low-nickel manganese ferromolten iron is periodically discharged from the rich slag furnace and can be cast into ingots or directly sent hot to steelmaking; the secondary slag generated after melting and separation, due to its stable composition and low content of harmful elements, can be directly used to produce slag powder, roadbed materials or microcrystalline glass products, achieving zero emission of solid waste throughout the entire process.

[0009] Furthermore, the nickel-containing smelting waste is one or more mixtures of nickel smelting water quenching slag, nickel-iron alloy smelting slag, nickel-containing dust, and nickel-containing sludge.

[0010] Furthermore, the carbonaceous reducing agent is one or more of anthracite powder, coke powder, and semi-coke, with a fixed carbon content ≥70%.

[0011] Furthermore, the flux is limestone or quicklime, used to adjust the slag basicity (CaO / SiO2 mass ratio) to 0.8-1.2 to facilitate reduction and slag-iron separation.

[0012] Furthermore, the binder is one of bentonite, carboxymethyl cellulose, or syrup.

[0013] Furthermore, in step S3, the atmosphere in the reduction section of the rotary hearth furnace is controlled to a CO volume concentration of 50-70% to prevent secondary oxidation of the pellets and ensure reduction efficiency.

[0014] Furthermore, in step S4, the rich slag furnace employs copper water jacket slag protection technology and stainless steel and copper composite material tuyeres to enhance the corrosion resistance of key parts of the furnace body to complex molten slag and extend the furnace lining life. In addition, the rich slag furnace features a wide production load adjustment range (50%-100%), enabling it to flexibly adapt to fluctuations in the source and composition of nickel-containing smelting waste, ensuring stable and smooth production.

[0015] Furthermore, in step S4, carbon powder or ferrosilicon powder can be sprayed simultaneously with oxygen-enriched air as needed to perform deep reduction and fine-tuning of the alloy composition, so as to ensure the recovery rate of manganese and accurately control the content of harmful elements such as phosphorus and sulfur in low-nickel ferromanganese.

[0016] The beneficial effects of this invention are as follows: (1) High degree of comprehensive utilization of resources, turning waste into treasure: This invention uses nickel-containing smelting waste that is difficult to handle as the main raw material. It not only efficiently recovers high-value nickel and iron, but also pays special attention to and recovers manganese, which is often overlooked, and produces high-value nickel-manganese pig iron alloy, truly realizing the high-value resource utilization of solid waste.

[0017] (2) Advanced and efficient process flow: The combined process of "rotary hearth furnace pre-reduction - rich slag furnace melting" is adopted. The double-sided, multi-channel oxygen-enriched injection technology of the rich slag furnace creates a smelting environment with strong stirring and strong mass transfer, which greatly accelerates the reaction kinetics process, enabling the metal oxides in the pre-reduced pellets to be rapidly and thoroughly reduced and aggregated into alloy phase, significantly improving metal yield and production efficiency.

[0018] (3) High added value of products and controllable composition: The composition of the produced nickel-manganese pig iron (such as Ni: 1-5%, Mn: 2-10%, C: 3.5-4.5%) can be flexibly adjusted according to the downstream steelmaking demand through batching. It can be directly used as an alloy additive to produce nickel-manganese steel, reduce steelmaking costs, and reduce dependence on pure nickel and manganese ferroalloys.

[0019] (4) Environmentally friendly and zero-emission: The entire process achieves complete disposal of nickel-containing solid waste. The final products are only nickel-manganese pig iron and inert secondary slag that can be recycled. There is no solid waste discharge, which solves the environmental pollution problem caused by traditional stockpiling methods.

[0020] (5) Reliable equipment and strong adaptability: The copper water jacket slag protection and other key technologies adopted by the rich slag furnace enable it to withstand the chemical corrosion of nickel-containing waste slag, resulting in a long equipment life and low maintenance costs. Its wide production load adjustment capability is particularly suitable for treating industrial solid waste with unstable sources and quantities, enhancing the industrial applicability and economy of the process.

[0021] (6) Significant cost advantage: Compared with the RKEF process for processing primary laterite nickel ore, the raw material cost of this method is extremely low; compared with adding pure alloys in the steelmaking process, the nickel-manganese pig iron produced by this method has a significant cost advantage and has significant economic benefits.

[0022] Simultaneously achieve complete resource recovery and harmless treatment of waste. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process method described in this invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0025] Example 1: The main raw material is the water-quenched slag from a nickel-iron alloy enterprise. Its chemical composition by mass percentage is: TFe 40.5%, Ni 2.1%, Mn 3.8%, SiO2 20.3%, CaO 12.1%, Al2O3 5.2%, MgO 4.0%.

[0026] S1. Ingredients: Take 75 kg of the dried and crushed nickel slag, 18 kg of anthracite powder with a fixed carbon content of 78%, 5 kg of quicklime (used to adjust the slag basicity to 1.0), and 2 kg of bentonite. Mix them in a mixer for 15 minutes until uniform.

[0027] S2. Briquetting and Drying: The mixture is pressed into ellipsoidal green pellets with a diameter of 30mm using a double-roll briquetting machine. The green pellets are then placed on a chain grate machine and dried in hot air at 300℃ for 6 hours to obtain dry pellets with a compressive strength >500N / pellet.

[0028] S3. Rotary hearth furnace pre-reduction: Dry pellets are placed into the reduction section of the rotary hearth furnace, coal gas is introduced, and the CO concentration in the reduction section is controlled at approximately 60%. Reduction is carried out at 1250℃ for 25 minutes. The pellets exiting the furnace are tested and show a metallization rate of 89% at a temperature of approximately 1100℃.

[0029] S4. Rich Slag Furnace Melting: Hot metallized pellets are directly added to the rich slag furnace through a closed chute. A dual-sided, multi-channel blowing system is activated, injecting 70% oxygen-enriched air into the molten pool. The intense stirring action rapidly heats and homogenizes the molten pool. By adjusting the oxygen enrichment rate and fuel supply, the molten pool temperature is stably controlled at 1580℃. After 20 minutes of smelting, slag and iron are fully separated. The wide load adjustment characteristics of the rich slag furnace ensure high efficiency and stability of the smelting process at this scale.

[0030] S5. Product Output: Low-nickel manganese ferromolten iron is discharged. Sampling analysis shows the following composition: C 4.2%, Si 0.8%, Mn 4.5%, Ni 2.3%, P 0.03%, S 0.02%, with the balance being Fe. This molten iron can be used as a high-quality steelmaking additive after casting into ingots. The discharged secondary slag composition is: FeO < 2%, CaO / SiO2 ≈ 1.0. After water quenching, it can be used as a cementitious material.

[0031] Example 2: The raw material is a mixture of nickel-containing flue dust and nickel-containing sludge. The chemical composition after mixing is approximately: TFe 35.2%, Ni 3.5%, Mn 5.2%, SiO2 15.8%, CaO 8.5%, ZnO 2.5%.

[0032] S1. Ingredients: Take 70kg of pretreated mixed waste, 20kg of coke powder, 6kg of limestone, 1.5kg of carboxymethyl cellulose solution (dry weight), and appropriate amount of water. After mixing, use a disc pelletizer to form Φ15mm green pellets.

[0033] S2. Drying: Dry the green balls at 250℃ for 8 hours.

[0034] S3, Rotary hearth furnace pre-reduction: Reduction at 1200℃ and CO atmosphere concentration of 55% for 35 minutes to obtain hot pellets with a metallization rate of 86%.

[0035] S4. Rich Slag Furnace Melting and Refining: Hot pellets are added to the rich slag furnace, and the molten pool temperature is controlled at 1550℃ by injecting 65% oxygen-enriched air. For deep manganese reduction and desulfurization, a mixed airflow of ferrosilicon powder (containing 75% Si) and oxygen-enriched air is injected through an independent duct. Composite material tuyeres ensure stable operation under these complex injection conditions. After melting, low-nickel ferromanganese is obtained with the following composition: C 3.8%, Mn 6.8%, Ni 3.6%, S 0.015%. The ZnO content in the secondary slag is enriched to ~8%, allowing for further zinc recovery.

[0036] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A process for producing low-nickel ferromanganese from nickel-containing smelting waste, characterized in that, Includes the following steps: S1. Raw material pretreatment and batching: The nickel-containing smelting waste is dried, crushed and screened; according to the mass percentage, 60-85% of the treated nickel-containing smelting waste, 10-25% of carbonaceous reducing agent, 3-10% of flux and 1-5% of binder are mixed and batched. S2. Gathering and Drying: The evenly mixed ingredients are formed into green pellets or green bodies, and then dried at 200-400℃ to obtain dry pellets. S3. Rotary hearth furnace pre-reduction: Dry pellets are placed into a rotary hearth furnace and reduced at 1150-1300℃ in a reducing atmosphere for 15-40 minutes to obtain hot metallized pellets with a metallization rate ≥85%. S4. Final reduction and smelting in rich slag furnace: The hot metallized pellets are directly charged into the rich slag furnace. Oxygen-enriched air is blown into the molten pool through the two sides and multiple air ducts of the rich slag furnace for strong stirring and smelting, and the temperature of the molten pool is controlled at 1500-1650℃. S5. Product output and slag treatment: Low-nickel manganese ferromolten iron is discharged from the rich slag furnace, and the secondary slag generated after smelting is utilized for resource recovery.

2. The process method according to claim 1, characterized in that, The nickel-containing smelting waste in step S1 is one or more mixtures of nickel smelting water quenching slag, nickel-iron alloy smelting slag, nickel-containing dust, and nickel-containing sludge.

3. The process method according to claim 1, characterized in that, The carbonaceous reducing agent in step S1 is one or more of anthracite powder, coke powder, and semi-coke, wherein the fixed carbon content is ≥70%.

4. The process method according to claim 1, characterized in that, The flux in step S1 is limestone or quicklime, used to adjust the slag basicity CaO / SiO2 mass ratio to 0.8-1.

2.

5. The process method according to claim 1, characterized in that, The binder in step S1 is one of bentonite, carboxymethyl cellulose, or syrup.

6. The process method according to claim 1, characterized in that, In step S3, the atmosphere in the reduction section of the rotary hearth furnace is controlled to have a CO volume concentration of 50-70%.

7. The process method according to claim 1, characterized in that, In step S4, the oxygen concentration of the oxygen-enriched air is 50%-90%.

8. The process method according to claim 1 or 7, characterized in that, In step S4, while oxygen-enriched air is being sprayed, carbon powder or ferrosilicon powder is also being sprayed to perform deep reduction and fine-tuning of the alloy composition.

9. The process method according to claim 1, characterized in that, In step S5, the chemical composition of the low-nickel manganese iron molten iron is as follows (mass percentage): C 3.5-4.5%, Ni 1.0-5.0%, Mn 2.0-10.0%, P≤0.05%, S≤0.04%, with the balance being Fe and unavoidable impurities.

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