Method for directly reducing copper-nickel alloy from high-nickel copper ore converting slag

Abstract

This invention relates to the field of non-ferrous metal metallurgy, specifically to a method for directly reducing high-nickel copper ore smelting slag to prepare copper-nickel alloys. The method includes: crushing and drying the high-nickel copper ore smelting slag to obtain pretreated slag; mixing the pretreated slag, composite reducing agent, and slag-forming flux into a mixed furnace charge, adding it to a vertical reduction furnace, and sequentially performing heating and holding reduction operations; then holding the furnace at room temperature for stratification; the lower layer yields a copper-nickel alloy, the middle layer yields iron slag, and the upper layer yields reduced slag. This invention targets high-nickel copper ore smelting slag, achieving copper-nickel preferential alloying through precise control of the composite reducing agent ratio and atmosphere, selectively retaining iron in the slag, directly producing a refinable crude alloy, realizing efficient copper-nickel reduction and iron recovery; eliminating the need for multi-furnace coordination and wet pretreatment stages, and simultaneously recovering three valuable metals (copper, nickel, and iron) through a three-phase stratification design; the process is shortened by more than 30% compared to traditional pyrometallurgical depletion processes.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal metallurgy, and specifically to a method for preparing copper-nickel alloys by reduction of high-nickel copper ore blowing slag. Background Technology

[0002] High-nickel copper ore smelting slag is a core byproduct of the converter blowing process in the pyrometallurgical smelting of copper-nickel sulfide ores. In the mainstream copper-nickel ore smelting process, the mined copper-nickel sulfide ore is enriched through beneficiation to obtain copper-nickel concentrate. The copper-nickel concentrate is then fed into smelting equipment such as flash furnaces and pool furnaces for matte smelting. After removing some gangue and sulfur, low-nickel matte is produced. The low-nickel matte is then fed into a converter for oxidation blowing, where most of the iron and sulfur impurities are removed through blast oxidation, ultimately yielding high-nickel matte for subsequent electrolytic refining. The slag formed by the oxidation of iron and the combination of slag-forming agents such as silica during the blowing process is the high-nickel copper ore smelting slag, also commonly referred to in the industry as nickel converter slag. In addition, flash furnace slag and smelting furnace slag produced in the copper-nickel ore smelting process, which also contain a certain amount of valuable copper and nickel metals, are often co-processed with the blowing slag and belong to the category of nickel-containing slag byproducts of high-nickel copper ore smelting.

[0003] High-nickel copper ore slag is characterized by high iron content, arsenic-free / low arsenic content, and large grade fluctuations. The main components of this type of slag are iron oxides and silicates, with iron content typically being the highest. It exists primarily in stable mineral forms such as fir olivine and magnetic iron oxide, resulting in a dense slag structure. The residual copper, nickel, cobalt, and other valuable metals are finely embedded, making efficient dissociation and recovery difficult with conventional physical sorting processes. Influenced by factors such as the grade of the concentrate entering the furnace, smelting operating parameters, and adjustments to the slag-forming system, the copper and nickel content of slag varies significantly between different smelting enterprises and production batches, leading to large fluctuations in raw material composition and posing significant challenges to large-scale, standardized recycling. Furthermore, because this type of slag contains leached heavy metals, it falls under the category of hazardous solid waste. Direct stockpiling without treatment would not only result in a serious waste of strategic non-ferrous metal resources such as copper and nickel but also pose an environmental risk of heavy metal leakage and pollution of surrounding soil and water bodies. Therefore, achieving the harmless disposal and efficient recovery of valuable metals from high-nickel copper ore smelting slag is a core necessity for the copper-nickel smelting industry to achieve green, low-carbon, and resource-recycling development.

[0004] Currently, the recycling and treatment processes for high-nickel copper ore smelting slag are mainly divided into two categories: hydrometallurgical processes and pyrometallurgical processes. Hydrometallurgical processes rely on acid leaching and alkaline leaching, using leaching agents to dissolve valuable metals in the slag into the liquid phase, followed by extraction, purification, and electrowinning to obtain the metal product. Pyrometallurgical processes, on the other hand, rely on reduction smelting, using high-temperature reduction to reduce copper and nickel oxides in the slag to their metallic state, followed by enrichment and separation to obtain alloys or high-grade matte products. Compared to hydrometallurgical processes, pyrometallurgical processes have significant comprehensive advantages: First, it has stronger raw material adaptability. Pyrometallurgical processes are more tolerant of slag composition fluctuations and mineral dispersal patterns. There is no need to make significant adjustments to the core process flow for raw materials of different grades and slag types. It can adapt to the large-scale and continuous processing of blowing slag produced in different smelting scenarios. Secondly, the processing flow is shorter and the production efficiency is higher. The pyrometallurgical process can complete the reduction, enrichment and separation of valuable metals through a short process. The single batch processing capacity is large and the production cycle is short. It can be directly connected to the existing pyrometallurgical production system of the smelter to realize the immediate disposal of slag. Third, the environmental and cost advantages are more prominent. Pyrometallurgical processes do not generate large amounts of acidic wastewater or organic extraction waste liquid. The flue gas generated during the production process can be centrally treated by the supporting dust removal and acid production systems to meet emission standards, making environmental management easier. At the same time, pyrometallurgical processes consume less reagents and can make full use of the existing waste heat and surplus capacity of the smelter to reduce production energy consumption. The unit processing cost under large-scale production is significantly lower than that of hydrometallurgical processes.

[0005] However, the existing pyrometallurgical processes still have problems such as poor reduction selectivity, low copper and nickel recovery rate, unstable alloy grade, and high energy consumption. They are difficult to achieve efficient recovery, low-consumption production, and full resource utilization of high-nickel copper ore slag. There is an urgent need to develop a pyrometallurgical process with a short process, strong adaptability, high recovery rate, and good comprehensive benefits.

[0006] The copper, nickel, and iron elements in the high-nickel copper ore smelting slag all have recycling value. However, current technologies cannot recover all three elements simultaneously from the high-nickel copper ore smelting slag.

[0007] For example, CN102719676A discloses a method for rapidly reducing copper slag to produce iron-copper alloy micro powder. This method involves mixing copper slag, reducing agent, and additives in a specific ratio, grinding them finely, adding a binder and water to form pellets or briquettes, drying them, and then spreading them evenly in a reducing atmosphere kiln. Rapid reduction is then performed at 1250-1450℃. The reduction product is cooled, crushed, and wet-milled for separation to obtain iron-copper alloy micro powder. The core objective is to extract iron from ferrosilicon in copper slag, achieving co-recovery of copper and iron, and recovering waste gas heat energy. This technology requires pretreatment through pelletizing / briquetting, employs a rapid reduction mode, and requires subsequent crushing and separation. The product is iron-copper alloy micro powder, which requires further processing before utilization. It cannot achieve efficient reduction and alloying of nickel, is not suitable for processing high-nickel materials, and has high subsequent processing costs for the micro powder product.

[0008] CN113957243A addresses high-grade, high-nickel matte using a two-stage atmospheric leaching + pressurized oxidative leaching + pressurized leaching fully hydrometallurgical process. This achieves selective leaching of nickel and iron, while copper and precious metals are retained and enriched in the slag, producing nickel sulfate solution, high-grade copper slag, and high-grade iron slag, respectively. However, this method focuses on the refined separation of high-grade intermediate products and the enrichment of precious metals. The raw material processed is high-nickel matte in the form of copper-nickel-iron sulfide melts, which are smelting intermediate products rather than by-product slag, making it unsuitable for high-nickel copper ore smelting slag. Furthermore, the fully hydrometallurgical process involves high equipment investment and complex operation. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for the direct reduction of high-nickel copper ore smelting slag to prepare copper-nickel alloys, which can realize the recovery of copper, nickel and iron.

[0010] The technical solution adopted by this invention to solve its technical problem is as follows: A method for directly reducing high-nickel copper ore smelting slag to prepare copper-nickel alloy, comprising: crushing and drying high-nickel copper ore smelting slag to obtain pretreated slag; mixing the pretreated slag, composite reducing agent, and slag-forming flux evenly to obtain mixed furnace charge, wherein the slag basicity of the mixed furnace charge is 0.4~0.6; the composite reducing agent is a mixture of coke and ferrous sulfide, wherein coke accounts for 70wt%~80wt%; the amount of the composite reducing agent is 12wt%~16wt% of the mass of the pretreated slag; The mixed charge is added to a vertical reduction furnace equipped with an atmosphere control device, and heating and holding reduction operations are performed sequentially. During the heating stage, a protective gas is introduced to prevent oxidation of the charge, and the temperature is raised to 1380-1450℃. During the holding reduction stage, the atmosphere inside the furnace is adjusted to a weakly reducing atmosphere: the volume of carbon monoxide is controlled to be 55-65% of the total volume of carbon monoxide and carbon dioxide, and the excess oxygen coefficient is 0.65-0.75. After the holding reduction is completed, the furnace temperature is adjusted to 1350℃-1400℃ and allowed to stand and separate into layers. The lower layer is a copper-nickel alloy, the middle layer is iron slag, and the upper layer is reducing slag. The metallic element composition of the high-nickel copper ore smelting slag includes: Ni: 0.89wt%~5.0wt%; Cu: 0.12wt%~1.5wt%; Fe: 40wt%~66wt%.

[0011] Preferably, the main chemical composition of the high-nickel copper ore smelting slag includes: Ni: 0.89wt%~5.0wt%; Cu: 0.12wt%~1.5wt%; Fe: 40wt%~66wt%; SiO2: 20wt%~35wt%; MgO: 2.0wt%~8.0wt%; CaO: 1.1wt%~2.0wt%.

[0012] Preferably, the pretreated residue has a particle size ≤0.1mm, and more than 85wt% of the particles have a particle size ≤0.075mm, and a moisture content ≤2wt%.

[0013] Preferably, the coke has a fixed carbon content of ≥85wt%.

[0014] Preferably, the purity of ferrous sulfide is ≥90wt%.

[0015] Preferably, the slag-forming flux is a mixture of silica and limestone, wherein silica accounts for 60wt% to 70wt%; the amount of the slag-forming flux is 5wt% to 8wt% of the mass of the pretreated slag.

[0016] Preferably, the heating stage is performed by heating to 1380-1450°C at a rate of 10-15°C / min.

[0017] Preferably, the protective gas is nitrogen; the flow rate of the protective gas is 0.5~1.0 Nm³. 3 / ton of furnace charge.

[0018] Preferably, the heat preservation and reduction time is 2.0~3.5h.

[0019] Preferably, the settling time is 30-60 minutes.

[0020] Preferably, the iron slag undergoes a secondary strong reduction process to recover molten iron.

[0021] Preferably, the reducing slag is subjected to water quenching and solidification treatment, and then cooled to room temperature to form a calcium-silicon glass body, which is used as a building material.

[0022] The present invention has the following beneficial effects: (1) This invention targets the slag of high-nickel copper ore smelting. By precisely controlling the ratio of composite reducing agent and atmosphere, copper and nickel are preferentially alloyed, and iron is selectively left in the slag, directly producing a refinable crude alloy, thus achieving efficient reduction of copper and nickel and recovery of iron. (2) The reduction and initial stratification are completed in one integrated single-furnace vertical reduction furnace, eliminating the need for multi-furnace coordination and wet pretreatment. The three-phase stratification design allows for the simultaneous recovery of three valuable metals: copper, nickel, and iron. The process is shortened by more than 30% compared to the traditional pyrometallurgical depletion process. The protective gas reduces the oxidation loss of the furnace charge, and precise temperature control and atmosphere regulation avoid high-temperature ineffective energy consumption, resulting in a 15-20% reduction in energy consumption per unit product. (3) Nickel recovery rate ≥90%, copper recovery rate ≥93%; Cu+Ni total content in crude copper-nickel alloy ≥82%, which improves the recovery rate by 5~8% compared with the existing direct reduction process and significantly reduces the subsequent refining load. Detailed Implementation

[0023] To make the objectives, solutions, and beneficial technologies of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be noted that the embodiments described in this specification are merely illustrative of the invention and are not intended to limit the invention.

[0024] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0025] The equipment and raw materials used in the embodiments are all industrial-grade conventional products. Operations without specific conditions are performed according to conventional smelting processes. The purpose is to further illustrate the feasibility of the technical solution, rather than to limit the scope of protection of the present invention.

[0026] In this description, it should be noted that, unless otherwise stated, "above" and "below" include the stated number, "multiple" in "one or more" means two or more, and "more than" in "one or more" means two or more.

[0027] This invention provides a method for directly reducing high-nickel copper ore smelting slag to prepare copper-nickel alloys, comprising: crushing and drying high-nickel copper ore smelting slag to obtain pretreated slag; mixing the pretreated slag, a composite reducing agent, and a slag-forming flux evenly to obtain a mixed furnace charge, wherein the slag basicity of the mixed furnace charge is 0.4~0.6; the composite reducing agent is a mixture of coke and ferrous sulfide, wherein the coke accounts for 70wt%~80wt%; the amount of the composite reducing agent used is 12wt%~16wt% of the mass of the pretreated slag; The mixed charge is added to a vertical reduction furnace equipped with an atmosphere control device, and heating and holding reduction operations are performed sequentially. During the heating stage, a protective gas is introduced to prevent oxidation of the charge, and the temperature is raised to 1380-1450℃. During the holding reduction stage, the atmosphere inside the furnace is adjusted to a weakly reducing atmosphere: the volume of carbon monoxide is controlled to be 55-65% of the total volume of carbon monoxide and carbon dioxide, and the excess oxygen coefficient is 0.65-0.75. After the holding reduction is completed, the furnace temperature is adjusted to 1350℃-1400℃ and allowed to stand and separate into layers. The lower layer is a copper-nickel alloy, the middle layer is iron slag, and the upper layer is reducing slag. The metallic element composition of the high-nickel copper ore smelting slag includes: Ni: 0.89wt%~5.0wt%; Cu: 0.12wt%~1.5wt%; Fe: 40wt%~66wt%.

[0028] In this scheme, the composite reducing agent is a key factor affecting the reduction effect and directly relates to the final recovery result. The synergistic ratio of the two is the core control point of this scheme. When the amount of ferrous sulfide is too low, the reduction and enrichment effect on nickel will decrease significantly, the alloy grade will be significantly reduced, the subsequent refining load will increase, and the scheme will lose its product quality advantage. When the amount of coke is too low, the reduction capacity for both copper and nickel will be insufficient, and both copper and nickel levels will decrease simultaneously.

[0029] For high-Fe slag with Fe content of 40%~66%, the basicity needs to be optimized to improve slag fluidity. In this scheme, the slag basicity (CaO mass: SiO2 mass) is directly related to the chemical reaction in the furnace at high temperature. This scheme adjusts the slag basicity through slag-forming flux. If the slag basicity is too low, it will lead to increased slag viscosity, decreased slag fluidity, and difficulty in settling and stratification. If the slag basicity is too high, it will increase the temperature required for the reaction and the holding temperature, increasing energy consumption and also causing incomplete separation of copper-nickel alloy from slag, thus reducing the recovery rate.

[0030] This solution targets high-nickel copper ore smelting slag. Through precise control of the mixed furnace charge formula and atmosphere, a direct reduction reaction is carried out in the furnace, reducing copper and nickel oxides to elemental metals and polymerizing them into copper-nickel alloys. Iron is partially reduced and enters the iron slag, while gangue components and flux form the slag. Copper and nickel are preferentially alloyed, while iron is selectively retained in the slag. The resulting reduction products—copper-nickel alloy, iron slag, and reduced slag—have density differences. By using a vertical reduction furnace and holding the furnace at a constant temperature for a period after reduction, the reduction products can form a three-phase stratification from bottom to top: copper-nickel alloy, iron slag, and reduced slag. The lower layer of copper-nickel alloy can be discharged through the bottom outlet of the furnace and cast to obtain crude copper-nickel alloy. The overflow of the middle layer of iron slag can be sent to an auxiliary furnace for secondary strong reduction to recover molten iron. The upper layer of reduced slag is discharged and sent to the tailings disposal process, where it can be used as building material. This process eliminates the need for multi-furnace coordination and wet pretreatment, shortening the process by more than 30% compared to traditional pyrometallurgical depletion processes.

[0031] In some embodiments of the present invention, the main chemical composition of the high-nickel copper ore smelting slag includes: Ni: 0.89wt%~5.0wt%; Cu: 0.12wt%~1.5wt%; Fe: 40wt%~66wt%; SiO2: 20wt%~35wt%; MgO: 2.0wt%~8.0wt%; CaO: 1.1wt%~2.0wt%.

[0032] In some embodiments of the present invention, the high-nickel copper ore smelting slag includes flash furnace slag and / or converter slag of high-nickel copper ore.

[0033] In some embodiments of the present invention, the pretreated residue has a particle size ≤0.1mm, and more than 85wt% of the particles have a particle size ≤0.075mm, and a moisture content ≤2wt%.

[0034] In some embodiments of the present invention, the fixed carbon content of the coke is ≥85wt%.

[0035] In some embodiments of the present invention, the purity of ferrous sulfide is ≥90wt%.

[0036] In some embodiments of the present invention, the slag-forming flux is a mixture of silica and limestone, wherein silica accounts for 60wt% to 70wt%; the amount of the slag-forming flux is 5wt% to 8wt% of the mass of the pretreated slag. The slag-forming flux is used to adjust the slag basicity of the mixed furnace charge to 0.4 to 0.6, and the above-mentioned formulation has a good adjustment effect.

[0037] In some embodiments of the present invention, the heating stage is performed by heating to 1380-1450°C at a rate of 10-15°C / min.

[0038] In some embodiments of the present invention, the protective gas is nitrogen; the flow rate of the protective gas is 0.5~1.0 Nm³. 3 / ton of furnace charge.

[0039] In some embodiments of the present invention, the heat preservation and reduction time is 2.0 to 3.5 hours. Within this time period, the reaction is relatively complete, and the duration is reasonable. Excessive time will lead to increased energy consumption and product costs.

[0040] In some embodiments of the present invention, the settling time is 30-60 minutes. This time period allows for material stratification within the furnace, and the duration is reasonable. Since heat preservation is required during the settling process, excessively long periods will increase energy consumption and product costs.

[0041] In some embodiments of the present invention, the iron slag undergoes secondary strong reduction to recover molten iron. The copper and nickel in the high-nickel copper ore smelting slag essentially enter the copper-nickel alloy, while the iron slag has a high iron content. Further processing of the iron slag can recover the iron resources from the high-nickel copper ore smelting slag.

[0042] In some embodiments of the present invention, the reducing slag is subjected to water quenching and solidification treatment, and then cooled to room temperature to form a calcium-silicon glassy substance, which is used as a building material. The reducing slag obtained by the method of the present invention has a heavy metal leaching content that meets the GB5085.3-2007 standard, and can be used as a building aggregate or road base material for resource utilization without secondary pollution.

[0043] Example The following examples describe the disclosure of this invention in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight. Unless otherwise stated, all reagents used in the examples are available commercially or synthesized using conventional methods and are ready for use without further processing. Unless otherwise stated, all instruments used in the examples are available commercially.

[0044] Example 1 The high-nickel copper ore smelting slag processed in this embodiment is high-nickel copper ore converter slag, and its chemical composition includes: Ni 4.5wt%, Cu 1.2wt%, Fe 43wt%, SiO2 25wt%, MgO 7.0wt%, and CaO 1.5wt%.

[0045] This embodiment describes a method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag, including: (1) Raw material preparation: Select high-nickel copper ore converter slag, crush it to a particle size ≤ 5 mm, then ball mill it to a particle size ≤ 0.1 mm, and 85 wt% of the particle size < 0.075 mm, and dry it to a moisture content of 1.5 wt% to obtain pretreated slag; (2) Batching and mixing: Weigh 100kg of pretreated slag, add 16kg of composite reducing agent (containing 12.8kg of coke, 3.2kg of ferrous sulfide, mass ratio 8:2; coke fixed carbon content 90wt%, ferrous sulfide purity 93wt%) and 8kg of slag-forming flux (containing 4.8kg of silica, 3.2kg of limestone, mass ratio 6:4); mix for 35min to obtain mixed furnace charge; (3) Direct reduction reaction: The mixed charge is added to a vertical reduction furnace equipped with an atmosphere control device, and nitrogen gas is introduced for protection (0.7 Nm³ of nitrogen per ton of charge). 3 The temperature was increased to 1440℃ at a rate of 15℃ / min; the atmosphere inside the furnace was adjusted to a weakly reducing atmosphere for heat preservation and reduction: the atmosphere was controlled so that the volume of carbon monoxide accounted for 65% of the total volume of carbon monoxide and carbon dioxide, the oxygen excess coefficient was 0.65, and the heat preservation and reduction time was 2.0h. (4) Separation of alloy and slag: Keep the furnace temperature at 1390℃ and let it stand for 35 minutes to allow the materials in the furnace to separate into layers. The lower layer is copper-nickel alloy, the middle layer is iron slag, and the upper layer is reducing slag. 7.8 kg of the lower copper-nickel alloy is discharged through the discharge port at the bottom of the furnace body and cast into a crude copper-nickel alloy. The middle layer of iron slag is introduced into the auxiliary furnace for secondary reduction to recover molten iron. The upper layer of reducing slag is discharged. (5) Tailings disposal: After the reduction residue is quenched and solidified by water, the leaching amount of heavy metals is tested. The results meet the GB 5085.3-2007 standard and it is used as building aggregate for future use.

[0046] The crude copper-nickel alloy was tested. Test results: The crude copper-nickel alloy contained 18% Cu and 66% Ni, with a total Cu+Ni content of 84%; Cu recovery rate was 94.0%, and Ni recovery rate was 91.2%. The energy consumption per unit product was reduced by 18% compared to the traditional process.

[0047] Comparative Example 1-1 This comparative example, based on Example 1, adjusts the mass ratio of coke to ferrous sulfide in the composite reducing agent to 9:1 (original ratio 8:2 in Example 1); the raw materials, process, and other parameters are the same as in Example 1. After raw material preparation, batching and mixing, direct reduction reaction, alloy and slag separation, and tailings disposal, 7.2 kg of crude copper-nickel alloy was obtained.

[0048] Testing revealed that the composition was 17.5% Cu and 58.2% Ni, with a total Cu+Ni content of 75.7%. The Cu recovery rate was 91.3%, and the Ni recovery rate was 78.5%. This comparative example used insufficient ferrous sulfide, resulting in a significant decrease in the reduction and enrichment effect on nickel. The nickel recovery rate was 12.7% lower than in Example 1, and the alloy grade was significantly reduced, increasing the subsequent refining load.

[0049] Comparative Examples 1-2 This comparative example, based on Example 1, adjusted the mass ratio of silica to limestone in the slag-forming flux to 8:2 (original ratio 6:4 in Example 1), reducing the slag basicity (CaO / SiO2) to 0.3 for testing (original basicity 0.4~0.6). For adaptability adjustments, the settling time was increased to 90 minutes. The raw materials, process, and other parameters remained the same as in Example 1. After raw material preparation, batching and mixing, direct reduction reaction, alloy and slag separation, and tailings disposal, 6.8 kg of crude copper-nickel alloy was obtained. Notably, after the direct reduction reaction, the slag fluidity was extremely poor, and even with an extended stratification time of 90 minutes, clear separation was still impossible.

[0050] Testing revealed that the obtained crude copper-nickel alloy contained 16.3% Cu and 55.1% Ni, with a total Cu+Ni content of 71.4%. The Cu recovery rate was 85.2%, and the Ni recovery rate was 72.3%. In this comparative example, the alkalinity was too low, resulting in increased slag viscosity, incomplete separation of the copper-nickel alloy from the slag, and a significant loss of valuable metals in the slag. The recovery rates were 8.8% and 18.9% lower than those in Example 1, respectively, representing a substantial decrease.

[0051] Comparative Examples 1-3 This comparative example, based on Example 1, adjusts the furnace atmosphere during the heat preservation reduction reaction, with carbon monoxide accounting for 70% of the total volume of carbon monoxide and carbon dioxide (65% in Example 1). The raw materials, process, and other parameters are the same as in Example 1. After raw material preparation, batching and mixing, direct reduction reaction, alloy and slag separation, and tailings disposal, 9.5 kg of crude copper-nickel alloy was obtained.

[0052] Testing revealed that the composition was Cu 14.2%, Ni 52.3%, and Fe 22.1%, with a total Cu+Ni content of 66.5%. The Cu recovery rate was 89.7%, and the Ni recovery rate was 80.1%. In this comparative reduction reaction, the atmosphere lacked sufficient reducing power, leading to excessive reduction of iron into the alloy. This resulted in a sharp increase in the iron content of the alloy, a significant decrease in the copper and nickel grades, a dramatic increase in subsequent impurity removal load, a reduction in the production of intermediate iron slag, and a decrease in iron resource recovery efficiency.

[0053] Example 2 The high-nickel copper ore smelting slag processed in this embodiment is high-nickel copper ore converter slag, with the following chemical composition: Ni 0.89%, Cu 0.53%, Fe 40.73%, SiO2 31.33%, MgO 7.19%, CaO 1.11%.

[0054] This embodiment describes a method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag, including: (1) Raw material preparation: Select high-nickel copper ore converter slag, crush it to a particle size ≤ 5 mm, then ball mill it to a particle size ≤ 0.1 mm, and 85 wt% of the particle size < 0.075 mm, and dry it to a moisture content of 1.2 wt% to obtain pretreated slag; (2) Batching and mixing: Weigh 100kg of pretreated slag, add 12kg of composite reducing agent (containing 8.4kg of coke, 3.6kg of ferrous sulfide, mass ratio 7:3; coke fixed carbon content 85wt%, ferrous sulfide purity 90wt%) and 5kg of slag-forming flux (containing 3.5kg of silica, 1.5kg of limestone, mass ratio 7:3); mix for 40min to obtain mixed furnace charge; (3) Direct reduction reaction: The mixed charge is added to a vertical reduction furnace equipped with an atmosphere control device, and nitrogen gas is introduced for protection (0.9 Nm³ of nitrogen per ton of charge). 3 The temperature was increased to 1390℃ at a rate of 10℃ / min; the atmosphere inside the furnace was adjusted to a weakly reducing atmosphere for heat preservation and reduction: the atmosphere was controlled so that the volume of carbon monoxide accounted for 55% of the total volume of carbon monoxide and carbon dioxide, the oxygen excess coefficient was 0.75, and the heat preservation and reduction time was 3.0h. (4) Separation of alloy and slag: Keep the furnace temperature at 1380℃ and let it stand for 50 minutes to allow the materials in the furnace to separate into layers. The lower layer is copper-nickel alloy, the middle layer is iron slag, and the upper layer is reducing slag. 1.8 kg of the lower copper-nickel alloy is discharged through the discharge port at the bottom of the furnace body and cast into a crude copper-nickel alloy. The middle layer of iron slag is introduced into the auxiliary furnace for secondary reduction to recover molten iron. The upper layer of reducing slag is discharged. (5) Tailings disposal: After the reduction residue is water-quenched and solidified, the leaching amount of heavy metals is tested. The results meet the GB 5085.3-2007 standard and are used as road base material for future use.

[0055] The crude copper-nickel alloy was tested. Test results: The crude copper-nickel alloy contained 28% Cu and 58% Ni, with a total Cu+Ni content of 86%. The Cu recovery rate was 93.5%, and the Ni recovery rate was 90.8%.

[0056] Comparative Example 2-1 This comparative example, based on Example 2, adjusts the mass ratio of coke to ferrous sulfide in the composite reducing agent to 6:4 (original ratio 7:3 in Example 2); the raw materials, process, and other parameters are the same as in Example 2. After raw material preparation, batching and mixing, direct reduction reaction, alloy and slag separation, and tailings disposal, 1.6 kg of crude copper-nickel alloy is obtained.

[0057] Testing revealed that the alloy contained 25.3% Cu, 52.1% Ni, and 3.2% S, with a total Cu+Ni content of 77.4%. The Cu recovery rate was 87.2%, and the Ni recovery rate was 82.5%. This comparative example used excessive amounts of ferrous sulfide, resulting in excessive sulfur content in the alloy, increasing the cost of subsequent desulfurization processes. Furthermore, this ratio led to insufficient reduction capacity, with copper and nickel recovery rates being 6.3% and 8.3% lower, respectively, compared to Example 2.

[0058] Comparative Example 2-2 This comparative example, based on Example 2, adjusted the mass ratio of silica to limestone in the slag-forming flux to 5:5 (original ratio 7:3 in Example 1), reducing the slag basicity (CaO / SiO2) to 0.7 for testing (original basicity 0.4~0.6). For adaptability adjustments, the reaction temperature and settling temperature were increased to 1480℃; the raw materials, process, and other parameters remained the same as in Example 2. After raw material preparation, batching and mixing, direct reduction reaction, alloy and slag separation, and tailings disposal, 1.7 kg of crude copper-nickel alloy was obtained. During the direct reduction reaction, the slag melting point increased, requiring a temperature increase to 1480℃ to maintain fluidity, resulting in a 22% higher energy consumption per unit product compared to Example 2.

[0059] Testing revealed that the obtained crude copper-nickel alloy contained 26.1% Cu and 54.3% Ni, with a total Cu+Ni content of 80.4%. The Cu recovery rate was 89.7%, and the Ni recovery rate was 86.2%. In this comparative example, excessive alkalinity led to an increase in the slag melting point, a sharp increase in energy consumption, and increased slag viscosity. Furthermore, the separation of the copper-nickel alloy from the slag was incomplete, resulting in recovery rates that were 3.8% and 4.6% lower than those in Example 2, respectively.

[0060] Example 3 The high-nickel copper ore smelting slag processed in this embodiment is high-nickel copper ore converter slag, with the following chemical composition: Ni 0.89%, Cu 0.53%, Fe 40.73%, SiO2 31.33%, MgO 7.19%, CaO 1.11%.

[0061] This embodiment describes a method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag, including: (1) Raw material preparation: Select high-nickel copper ore converter slag, crush it to a particle size ≤ 5 mm, then ball mill it to a particle size ≤ 0.1 mm, and 85 wt% of the particle size < 0.075 mm, and dry it to a moisture content of 1.0 wt% to obtain pretreated slag; (2) Batching and mixing: Weigh 100kg of pretreated slag, add 15kg of composite reducing agent (containing 11.25kg of coke, 3.75kg of ferrous sulfide, mass ratio 7.5:2.5; fixed carbon content of coke 85wt%, purity of ferrous sulfide 90wt%) and 6kg of slag-forming flux (6kg of limestone); mix for 30min to obtain mixed furnace charge; (3) Direct reduction reaction: The mixed charge is added to a vertical reduction furnace equipped with an atmosphere control device, and nitrogen gas is introduced for protection (0.5 Nm³ of nitrogen per ton of charge). 3 The temperature was increased to 1420℃ at a rate of 12℃ / min; the atmosphere inside the furnace was adjusted to a weakly reducing atmosphere for heat preservation and reduction: the atmosphere was controlled so that the volume of carbon monoxide accounted for 60% of the total volume of carbon monoxide and carbon dioxide, the oxygen excess coefficient was 0.7, and the heat preservation and reduction time was 3.5h. (4) Separation of alloy and slag: Keep the furnace temperature at 1360℃ and let it stand for 60 minutes to allow the materials in the furnace to separate into layers. The lower layer is copper-nickel alloy, the middle layer is iron slag, and the upper layer is reducing slag. 1.8 kg of the lower copper-nickel alloy is discharged through the discharge port at the bottom of the furnace and cast into a crude copper-nickel alloy. The middle layer of iron slag is introduced into the auxiliary furnace for secondary reduction to recover molten iron. The upper layer of reducing slag is discharged. (5) Tailings disposal: After the reduction residue is water-quenched and solidified, the leaching amount of heavy metals is tested. The results meet the GB 5085.3-2007 standard and are used as road base material for future use.

[0062] The crude copper-nickel alloy was tested. Test results: The crude copper-nickel alloy contained 28.5% Cu and 59% Ni, with a total Cu+Ni content of 87.5%. The Cu recovery rate was 94.2%, and the Ni recovery rate was 91.6%.

Claims

1. A method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore blowing slag, characterized in that, include: The high-nickel copper ore smelting slag is crushed and dried to obtain pretreated slag; the pretreated slag, composite reducing agent, and slag-forming flux are mixed evenly to obtain mixed furnace charge, the slag basicity of the mixed furnace charge being 0.4~0.6; the composite reducing agent is a mixture of coke and ferrous sulfide, wherein the coke accounts for 70wt%~80wt%; the amount of the composite reducing agent used is 12wt%~16wt% of the mass of the pretreated slag; The mixed furnace charge is added into a vertical reduction furnace equipped with an atmosphere control device, and heating and holding reduction operations are performed in sequence. During the heating stage, a protective gas is introduced to prevent oxidation of the furnace charge, and the temperature is raised to 1380-1450℃. During the heat preservation and reduction stage, the atmosphere inside the furnace is adjusted to a weakly reducing atmosphere: the volume of carbon monoxide is controlled to account for 55-65% of the total volume of carbon monoxide and carbon dioxide, and the excess oxygen coefficient is 0.65-0.75; after the heat preservation and reduction is completed, the furnace temperature is adjusted to 1350℃-1400℃ and allowed to stand and separate into layers; the lower layer is copper-nickel alloy, the middle layer is iron slag, and the upper layer is reducing slag. The metallic element composition of the high-nickel copper ore smelting slag includes: Ni: 0.89wt%~5.0wt%; Cu: 0.12wt%~1.5wt%; Fe: 40wt%~66wt%.

2. The method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag according to claim 1, characterized in that, The main chemical components of the high-nickel copper ore smelting slag include: Ni: 0.89wt%~5.0wt%; Cu: 0.12wt%~1.5wt%; Fe: 40wt%~66wt%; SiO2: 20wt%~35wt%; MgO: 2.0wt%~8.0wt%; CaO: 1.1wt%~2.0wt%.

3. The method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag according to claim 1, characterized in that, The pretreated residue has a particle size ≤0.1mm, and more than 85wt% of the particles have a particle size ≤0.075mm, and a moisture content ≤2wt%.

4. The method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag according to claim 1, characterized in that, The coke has a fixed carbon content of ≥85wt% and a ferrous sulfide purity of ≥90wt%.

5. The method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag according to claim 1, characterized in that, The slag-forming flux is a mixture of silica and limestone, wherein silica accounts for 60wt% to 70wt%; the amount of the slag-forming flux is 5wt% to 8wt% of the mass of the pretreated slag.

6. The method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag according to claim 1, characterized in that, During the heating phase, the temperature is increased to 1380-1450℃ at a rate of 10-15℃ / min.

7. The method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag according to claim 1, characterized in that, The protective gas is nitrogen; the flow rate of the protective gas is 0.5~1.0 Nm³. 3 / ton of furnace charge.

8. The method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag according to claim 1, characterized in that, The heat preservation and restoration time is 2.0~3.5h; the standing time is 30~60min.

9. The method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag according to any one of claims 1 to 8, characterized in that, The iron slag is subjected to secondary strong reduction to recover molten iron.

10. The method for preparing copper-nickel alloys by direct reduction of high-nickel copper ore smelting slag according to any one of claims 1 to 8, characterized in that, The reducing slag is subjected to water quenching and solidification treatment, and then cooled to room temperature to form a calcium-silicon glass body, which is used as a building material.