Metallurgical furnace for multi-stage smelting and dilution of copper-nickel sulfide ore

Abstract

The invention provides a metallurgical furnace for multi-stage smelting and dilution of copper-nickel sulfide ore, and belongs to the technical field of non-ferrous metal pyrometallurgy equipment. The device is provided with a first-stage space smelting area, a second-stage molten pool smelting area, a third-stage molten pool reduction smelting area and a fourth-stage depletion smelting area which are communicated in sequence; a feeding nozzle and a spray gun are arranged at the top of the first-stage space smelting area to realize material pre-oxidation and impurity volatilization, and a side-blowing spray gun is arranged in the second-stage molten pool smelting area to finish deep smelting and slag-matte separation; a third-stage molten pool reduction smelting area is provided with a spray gun to create a reducing atmosphere, and impurities such as lead and zinc are selectively reduced and volatilized to be removed; a controllable polarity electrode and a sulfuration reducing agent feeding hole are arranged at the top of the fourth-stage depletion smelting area, so that electromagnetic stirring, chemical reduction sulfuration and the like are realized. Through multi-zone collaborative design and functional coupling, the problems that in the existing copper-nickel sulfide ore pyrogenic process, the smelting strength is improved, the adaptability to raw materials is poor, the slag dilution efficiency is low, and impurity valuable metal elements are difficult to enrich are solved.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal pyrometallurgical technology and relates to a metallurgical furnace for multi-stage smelting and depletion of copper-nickel sulfide ores. Background Technology

[0002] Currently, pyrometallurgical furnaces used for pyrometallurgical smelting of nickel sulfide concentrate include electric arc furnaces, flash furnaces, top-blown furnaces, and side-blown furnaces. The product of smelting is low-nickel matte; among which: The smelting of electric arc furnaces requires roasting and pre-desulfurization of the materials fed into the furnace, which has problems such as a long process flow and high cost of roasting flue gas treatment. Moreover, the smelting process of electric arc furnaces has basically no desulfurization capacity, resulting in low-grade low-nickel matte and the inability to utilize the chemical heat of nickel sulfide in the smelting process, leading to high energy consumption and cost.

[0003] Flash smelting furnaces use oxygen-enriched air for smelting. The heat balance during the smelting process mainly relies on the exothermic reaction of the concentrate, accounting for more than 80% of the total heat energy. Therefore, flash smelting furnaces have high requirements for the quality of the concentrate entering the furnace. For example, the concentrate entering the furnace must have a sulfur content of ≥25%, a magnesium oxide content of ≤8%, a moisture content dried to ≤0.3%, and a particle size of -200 mesh ≥80%. This limits the types of materials that flash smelting furnaces can process and the efficiency of smelting.

[0004] The top-blown smelting furnace also uses oxygen-enriched smelting. Although it is well adaptable to the concentrate fed into the furnace, it can only process nickel sulfide concentrate with a magnesium oxide content of about 10%. During the smelting process, the oxygen-enriched air reacts with the sulfides in the concentrate to release heat, making full use of the latent chemical heat of the concentrate. However, since the concentrate fed into the furnace has a relatively high water content, a certain amount of coal needs to be added to the concentrate to supplement the heat. However, the proportion of coal burning in the furnace is relatively large, the heating efficiency of the molten pool is low, and there are problems such as insufficient fuel utilization.

[0005] Side-blown smelting furnaces can not only achieve oxygen-enriched smelting, but also use molten pool combustion technology, that is, injecting fuel into the molten pool to supplement heat and increase the reaction temperature. They are also more adaptable to concentrates and can process low-grade, low-sulfur concentrates with a magnesium oxide content of more than 10%.

[0006] In top-blown smelting furnaces, side-blown smelting furnaces, and other pool smelting furnaces, a large proportion of impurity elements such as lead and zinc enter the slag and nickel matte during the smelting process. On the one hand, this results in excessively high impurity element content in the product, poor quality, and high downstream impurity removal costs. On the other hand, it causes impurity elements such as lead and zinc, which have recycling value, to be dispersed in the dust, slag, and matte, failing to form enriched products that are conducive to recycling and utilization, thus preventing the full utilization of valuable metals in the resources.

[0007] In addition, traditional metallurgical furnaces generally require the addition of a settling electric furnace or electrode settling separation zone after remelting to deplete the slag. The molten pool in the settling electric furnace or electrode settling separation zone is in a relatively static or slightly moving state, resulting in poor kinetic conditions for slag matte settling separation. A relatively large molten pool zone is required to increase the settling separation time. Maintaining the thermal balance of the furnace body requires a large amount of energy, resulting in low depletion efficiency and high processing costs.

[0008] In view of the above-mentioned defects, a metallurgical furnace for multi-stage smelting and depletion of copper-nickel sulfide ore is proposed to solve the problems of poor adaptability to raw materials, low efficiency of slag depletion, and difficulty in enriching valuable metal elements in the pyrometallurgical process of copper-nickel sulfide ore.

[0009] A search revealed a Chinese invention patent application (application number: 202211732799.4) that is quite similar to the technical means of this invention. This technology is used as a prior art document, and the technical features that distinguish this invention from the prior art document are briefly described below: 1. In this invention, a primary space melting zone is provided with a primary melting zone spray gun on its side. The fuel and oxygen-enriched air added to the primary melting zone spray gun are burned and released heat in the primary space melting zone to increase the temperature and oxygen potential in the primary space melting zone. The material undergoes a melting reaction during the dispersion process in this space. In contrast, the prior art only adds secondary air to burn the combustible gas that has not been fully reacted in the molten pool. 2. The present invention provides nickel matte discharge outlets for the secondary smelting zone and the quaternary depleted smelting zone on the sidewalls of the secondary smelting pool and the quaternary depleted smelting zone, respectively, to discharge nickel matte from the secondary smelting pool and the quaternary depleted smelting zone, thereby achieving the purpose of smelting nickel matte of different grades. In contrast, the prior art only provides a nickel matte discharge outlet in the electrode area, which can only discharge nickel matte of one grade. 3. In this invention, the spray gun in the three-stage molten pool reduction smelting zone is located close to the surface of the molten pool, which creates a strong stirring effect on the surface of the molten pool, making it easier for the volatile impurity elements after reduction to be quickly separated from the molten pool. However, in the prior art, the spray gun is located deeper and does not have the function of reducing and removing volatile elements. 4. In this invention, a controllable polarity electrode is set in the four-stage depleted smelting zone. The polarity of the electrode is controlled by a power supply device. The molten pool in the four-stage depleted smelting zone will produce a stable directional movement in accordance with the direction of the current. The controllable polarity electrode, through periodic polarity control and exchange, causes the molten pool movement direction to change periodically, increasing the stirring effect of the molten pool, thereby increasing the probability of the aggregation and growth of tiny nickel matte droplets in the molten pool, which plays a role in reducing the content of valuable metals in the slag. In contrast, the prior art only sets a normal AC electrode, which only heats the molten pool and does not have the above-mentioned effects. 5. In this invention, the reduction of valuable metals in the slag within the fourth-stage depleted smelting zone is the result of the combined effects of chemical reduction sulfidation depletion and controllable polarity electrode depletion caused by the addition of reducing agent and sulfiding agent through the feeding hole in the fourth-stage depleted smelting zone. In contrast, in the prior art, the reducing sulfiding agent is added through the middle side blowing area. The different addition locations result in different mechanisms of action. Summary of the Invention

[0010] The purpose of this invention is to address the problems existing in the prior art by providing a metallurgical furnace for multi-stage smelting and depletion of copper-nickel sulfide ore, thereby solving problems such as poor adaptability of smelting intensity to raw materials, low efficiency of slag depletion, and difficulty in enriching valuable metal elements in the pyrometallurgical process of copper-nickel sulfide ore.

[0011] Therefore, the present invention adopts the following technical solution: A metallurgical furnace for multi-stage smelting and depletion of copper-nickel sulfide ore includes a furnace body, which adopts an integrated structure and has a primary spatial smelting zone, a secondary molten pool smelting zone, a tertiary molten pool reduction smelting zone, and a quaternary depletion smelting zone arranged in a continuous manner inside. The top of the primary space smelting zone is equipped with several feeding nozzles for adding smelting materials, and the interior is equipped with several primary smelting zone spray guns for injecting fuel and oxygen-enriched air. The secondary molten pool smelting zone is located directly below the primary molten space smelting zone, and the two are connected. The secondary molten pool smelting zone is equipped with several secondary smelting zone spray guns that inject fuel and oxygen-enriched air into the molten pool, as well as a secondary smelting zone nickel matte discharge port for discharging the produced nickel matte. The tertiary molten pool reduction smelting zone is located on one side of the secondary molten pool smelting zone along the length of the furnace body. The two are separated by a first water-cooled structural partition wall. A channel for the flow of molten material is provided below the first water-cooled structural partition wall. The tertiary molten pool reduction smelting zone is equipped with several tertiary molten pool reduction smelting zone spray guns that inject fuel and oxygen-enriched air into the molten pool. The fourth-level depletion smelting zone is located on the other side of the third-level molten pool reduction smelting zone along the length of the furnace body. The two are separated by a second water-cooled structural partition wall. A channel for the flow of melt is provided below the second water-cooled structural partition wall. The top of the fourth-stage depleted smelting zone is equipped with several controllable polarity electrodes, a feeding hole for adding reducing agent and sulfiding agent, a flue for the fourth-stage depleted smelting zone, and a slag discharge port and a nickel matte discharge outlet for the fourth-stage depleted smelting zone on the side.

[0012] The bottoms of both the first and second water-cooled structural partition walls are immersed in the molten pool. Their depths are configured to allow the melt to flow through the channels at the bottom of the partition walls, while preventing unreacted materials or slag floating on the surface of the molten pool from crossing the partition walls and entering the next area.

[0013] The nickel matte discharge outlet of the secondary smelting zone, the nickel matte discharge outlet of the fourth-stage depleted smelting zone, and the slag discharge outlet adopt one or more combinations of low-mouth combustion outlet discharge, siphon outlet discharge, or high-mouth overflow discharge.

[0014] The nickel matte discharge outlets of the fourth-stage depleted smelting zone and the nickel matte discharge outlets of the second-stage smelting zone are located at different positions at the bottom of the furnace body, and are used to discharge nickel matte products of different grades respectively.

[0015] The nozzle of the spray gun in the three-stage molten pool reduction smelting zone is set at a position close to the molten pool surface to strongly stir the slag layer on the surface of the molten pool, and promote the separation of the volatile metal substances generated by reduction from the molten pool into the flue gas.

[0016] The primary smelting zone is equipped with multi-stage smelting zone rising flues, which are used to discharge flue gas and are located above the furnace body.

[0017] The multi-stage smelting zone rising flue is symmetrically provided with several multi-stage smelting zone rising flue spray guns on both sides, which are used to inject fuel and oxygen-enriched air into the flue to perform secondary combustion and heat up the flue gas.

[0018] The controllable polarity electrode is staggered with the feeding holes of the fourth-stage depleted smelting zone.

[0019] The present invention also provides a method for smelting copper-nickel sulfide ore using the above-mentioned metallurgical furnace, comprising the following steps: The copper-nickel sulfide ore is added to the primary smelting zone through the feeding nozzle. Fuel and oxygen-enriched air are then injected through the spray gun in the primary smelting zone, causing the material to undergo an oxidation smelting reaction during its descent. Lead and zinc impurities volatilize and enter the flue gas. The reacted melt falls into the secondary molten pool smelting zone, where the required atmosphere and heat are replenished by the smelting lance to complete the deep smelting and slag-matte separation, producing the first nickel matte and releasing it through the nickel matte outlet of the secondary smelting zone; The slag flows into the three-stage molten pool reduction smelting zone through the bottom channel of the water-cooled structural partition wall. The reducing atmosphere in the three-stage molten pool smelting zone is controlled by the spray gun, which reduces the valuable metals into the matte layer, while reducing and volatilizing lead and zinc impurities. Before depletion, the slag flows into the fourth-stage depletion smelting zone through the bottom channel of the water-cooled structural partition wall. Reducing agent and sulfiding agent are added through the feeding hole of the fourth-stage depletion smelting zone for chemical depletion. The slag is heated by a controllable polarity electrode and subjected to periodically changing electromagnetic stirring to achieve electromagnetic-chemical synergistic deep depletion, producing the second nickel matte and the final slag, which are discharged through the slag discharge port and the nickel matte discharge outlet of the fourth-stage depletion smelting zone, respectively. The flue gas generated at each stage is collected and discharged through the multi-stage smelting zone's rising flue. The multi-stage smelting zone's rising flue spray guns perform secondary combustion on the flue gas. The flue gas generated in the fourth-stage lean smelting zone can be discharged through the fourth-stage lean smelting zone's flue.

[0020] The beneficial effects of this invention are as follows: This invention, by setting up multiple staged reaction zones within an integrated metallurgical furnace, fully integrates spatial smelting technology with pyrometallurgical gasification and impurity removal technology, molten pool combustion smelting technology, controllable electrode electromagnetic depletion technology, and reduction sulfide chemical depletion technology. This effectively solves problems encountered in the pyrometallurgical process of copper-nickel sulfide ores, such as poor adaptability to raw materials for increasing smelting intensity, low slag depletion efficiency, and difficulty in enriching valuable metal elements in impurities. It is also applicable to the processing of various high- and low-grade, complex, and difficult-to-process copper-nickel sulfide raw materials; specifically: 1. The materials processed by this invention are applicable to the processing of various complex multi-source nickel-copper sulfide raw materials of high and low grade, and have the characteristics of strong raw material applicability; 2. This invention integrates space smelting technology, pyrometallurgical gasification and impurity removal technology, molten pool combustion smelting technology, controllable electrode electromagnetic depletion technology, and reduction sulfide chemical depletion technology. Specifically: the first-stage space smelting zone has the advantage of easily controllable reaction atmosphere, thereby improving system thermal utilization; the second-stage molten pool smelting zone features high fuel utilization and good molten pool agitation; the third-stage molten pool reduction smelting zone has the advantage of precise control of the reducing atmosphere, achieving directional selective reduction and easy separation of volatile impurity elements from the molten pool; the fourth-stage depletion smelting zone employs a combination of reduction sulfide chemical depletion and controllable electrode electromagnetic enhanced depletion, which can deeply and efficiently deplete the slag, reducing the valuable metal content in the slag and improving the valuable metal recovery rate. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the device structure in Embodiment 1 of the present invention.

[0022] In the diagram: 1. Primary smelting zone; 2. Feed nozzle; 3. Primary smelting zone spray gun; 4. Secondary molten pool smelting zone; 5. Secondary smelting zone spray gun; 6. Secondary smelting zone nickel matte discharge outlet; 7. Water-cooled structural partition wall; 8. Tertiary molten pool reduction smelting zone; 9. Tertiary molten pool smelting zone spray gun; 10. Multi-stage smelting zone rising flue; 11. Multi-stage smelting zone rising flue spray gun; 12. Water-cooled structural partition wall; 13. Quaternary depletion smelting zone; 14. Quaternary depletion smelting zone feed hole; 15. Controllable polarity electrode; 16. Quaternary depletion smelting zone flue; 17. Slag discharge port; 18. Quaternary depletion smelting zone nickel matte discharge outlet. Detailed Implementation

[0023] The technical solution of the present invention will be described below with reference to the accompanying drawings and implementation methods.

[0024] Example 1 like Figure 1As shown, a metallurgical furnace for multi-stage smelting and depletion of copper-nickel sulfide ore includes a furnace body, which is an integrated fixed-bed furnace. Inside the furnace body are a primary spatial smelting zone 1, a secondary molten pool smelting zone 4, a tertiary molten pool reduction smelting zone 8, and a quaternary depletion smelting zone 13 arranged in a connected manner. The four zones share the same molten pool base, and the melt flows through each zone sequentially by gravity and position difference.

[0025] The top of the primary space smelting zone 1 is equipped with several feeding nozzles 2 for adding smelting materials, and the interior is equipped with several primary smelting zone spray guns 3 for injecting fuel and oxygen-enriched air. The smelting materials are added into the primary space smelting zone 1 through the feeding nozzles 2. As they fall from top to bottom, they are heated and their temperature rises. The sulfides in the smelting materials undergo an oxidation smelting reaction with the excess oxygen-enriched air added by the primary smelting zone spray guns 3. Under the action of high temperature and high oxygen potential, impurity elements such as lead and zinc in the copper-nickel sulfide ore begin to volatilize and enter the flue gas.

[0026] The primary space smelting zone 1 is equipped with a multi-stage smelting zone rising flue 10, which is located above the furnace body and is used to discharge the flue gas produced during the smelting process of the primary space smelting zone 1, the secondary molten pool smelting zone 4, and the tertiary reduction smelting zone 8. Specifically, the multi-stage smelting zone rising flue 10 is made of refractory insulation material to reduce the heat loss of flue gas when passing through the flue.

[0027] Several multi-stage smelting zone rising flue 10 are symmetrically arranged on both sides of the multi-stage smelting zone rising flue spray guns 11, which are used to inject fuel and excessive oxygen-enriched air into the flue. While carrying out secondary combustion of flue gas, the flue gas temperature is further increased, and the molten dust and lead fumes and zinc fumes generated by volatilization are prevented from condensing and sticking back to the molten pool in the flue due to the drop in flue gas temperature.

[0028] The secondary smelting pool 4 is located directly below the primary smelting pool 1, and the two are connected. The secondary smelting pool 4 is equipped with several secondary smelting zone lances 5 that inject fuel and oxygen-enriched air into the smelting pool, and a secondary smelting zone nickel matte discharge outlet 6 for discharging the produced nickel matte. The secondary smelting zone lances 5 are used to inject supplementary heat fuel and oxygen-enriched air required for further smelting into the smelting pool. The fuel and oxygen-enriched air are burned inside the smelting pool to release heat, maintain the thermal balance of the furnace and smelting reaction, and independently control the oxygen-enriched air to further smelt the smelting materials. The unreacted portion of fuel and smelting flue gas enters the primary smelting pool 1 in the first phase and is fully burned with the excess oxygen-enriched air injected by the primary smelting zone lances 2 to supplement the heat required for the smelting process in the primary smelting pool 1.

[0029] The gas supply and fuel systems of the primary melting zone spray gun 3 and the secondary melting zone spray gun 5 are independently controlled, so that a high oxygen potential and high temperature atmosphere is formed in the primary melting zone 1, while the melting reaction is completed in the secondary melting pool 4. The fuel and flue gas that have not been fully reacted from the secondary melting pool 4 rise into the primary melting zone 1 and are fully combusted with the excess oxygen-enriched air injected by the primary melting zone spray gun 3.

[0030] The tertiary reduction smelting zone 8 is located on one side of the secondary smelting zone 4 along the length of the furnace body. The two are separated by a first water-cooled structural partition wall 7. A channel for the flow of melt is provided below the first water-cooled structural partition wall 7. The first water-cooled structural partition wall 7 is used to prevent unreacted materials on the surface of the secondary smelting zone 4 from entering the interior of the tertiary reduction smelting zone 8, thereby avoiding the problem of incomplete smelting.

[0031] The three-stage molten pool reduction smelting zone 8 is equipped with several three-stage molten pool reduction smelting zone spray guns 9 that inject fuel and oxygen-enriched air into the molten pool. The fuel and oxygen-enriched air injected into the three-stage molten pool reduction smelting zone 8 are controlled to maintain a reducing atmosphere in the slag layer of the three-stage molten pool reduction smelting zone 8. The fuel and oxygen-enriched air burn in the molten pool to release heat, maintaining the thermal balance of the furnace and smelting reaction. Excess fuel undergoes a reduction reaction with some metal oxides in the slag layer. Valuable metals such as nickel and copper are reduced and enter the nickel matte layer. Impurity elements such as lead and zinc are reduced and generate metallic substances with lower boiling points, which are then separated from the molten pool along with the flue gas.

[0032] The spray gun 9 in the three-stage molten pool reduction smelting zone is positioned close to the surface of the molten pool, creating a strong stirring effect on the surface of the molten pool, which facilitates the rapid separation of volatile impurities from the molten pool after reduction.

[0033] The fourth-stage depleted smelting zone 13 is located on the other side of the third-stage molten pool reduction smelting zone 8 along the length of the furnace body. The two are separated by a second water-cooled structural partition wall 12. A channel for the flow of melt is provided below the second water-cooled structural partition wall 12. The water-cooled structural partition wall 12 is used to prevent unreacted materials on the surface of the third-stage molten pool reduction smelting zone 8 from entering the interior of the fourth-stage depleted smelting zone 13, thereby avoiding the problem of increased valence metal content in the slag.

[0034] The top of the fourth-stage depleted smelting zone 13 is equipped with several controllable polarity electrodes 15, a fourth-stage depleted smelting zone feeding hole 14 for adding reducing agent and sulfiding agent, and a fourth-stage depleted smelting zone flue 16. The side is equipped with a slag discharge port 17 and a fourth-stage depleted smelting zone nickel matte discharge outlet 18. The fourth-stage depleted smelting zone flue 16 is used to control the negative pressure in the furnace of the depleted smelting zone, and is also conducive to adopting different treatment processes for flue gas of different qualities. The controllable polarity electrodes 15 and the fourth-stage depleted smelting zone feeding hole 14 are arranged alternately.

[0035] The slag discharge port 17 adopts either a high-mouth overflow discharge or a low-mouth combustion port discharge, or both a high-mouth overflow discharge port and a low-mouth combustion port discharge port are set up at the same time to perform slag discharge operations alternately.

[0036] The feeding hole 14 in the fourth-stage depletion smelting zone is used to replenish the reducing agent and sulfiding agent required for the depletion process. After entering the fourth-stage depletion smelting zone 14, the reducing agent and sulfiding agent undergo a chemical reaction with the peroxidized valuable metal oxides in the slag to form sulfides with relatively high density that separate from the slag, thereby achieving the purpose of slag depletion.

[0037] The controllable polarity electrode 15 controls the electrode supply polarity through a power supply device. The molten pool in the fourth-stage depleted smelting zone 13 produces a stable directional movement in accordance with the current direction. The power supply device can periodically control and exchange the electrode supply polarity, so that the current direction of the melt flowing through the fourth-stage depleted smelting zone changes periodically, thereby generating a periodically changing electromagnetic stirring effect in the molten pool, which increases the probability of the aggregation and growth of tiny nickel matte droplets in the molten pool, and plays a role in reducing the content of valuable metals in the slag.

[0038] The reduction in valuable metals in the slag within the fourth-stage depleted smelting zone 13 is the result of the combined effects of chemical reduction and sulfidation depletion caused by the addition of reducing agent and sulfiding agent through the charging port 14 of the fourth-stage depleted smelting zone, and depletion by the controllable polarity electrode 15.

[0039] The bottoms of the first water-cooled structural partition wall 7 and the second water-cooled structural partition wall 12 are both immersed in the molten pool. Their depths are configured to allow the molten material to flow through the channels at the bottom of the partition wall, while preventing unreacted material or slag floating on the surface of the molten pool from crossing the partition wall into the next area.

[0040] The nickel matte discharge outlet 6 in the secondary smelting zone, the nickel matte discharge outlet 18 in the fourth-stage depleted smelting zone, and the slag discharge outlet 17 adopt one or more combinations of low-mouth burn-out discharge, siphon discharge, or high-mouth overflow discharge.

[0041] The secondary smelting zone nickel matte discharge outlet 6 and the fourth-level depleted smelting zone nickel matte discharge outlet 18 are respectively set on the side walls of the secondary smelting zone 4 and the fourth-level depleted smelting zone 13. These outlets are used to discharge nickel matte from the secondary smelting zone and the fourth-level depleted smelting zone, respectively, thereby achieving the purpose of smelting nickel matte of different grades.

[0042] The usage process of this embodiment is as follows: The smelting material is fed into the primary smelting zone 1 from the top through the feeding nozzle 2. Fuel and oxygen-enriched air are added into the primary smelting zone 1 through the primary smelting zone spray gun 3. The fuel and oxygen-enriched air burn and release heat in the primary smelting zone 1, increasing the temperature and oxygen potential within the zone. As the smelting material falls from top to bottom, it is heated and its temperature rises. The sulfides in the smelting material undergo an oxidation smelting reaction with the excess oxygen-enriched air added by the primary smelting zone spray gun 3. Under the influence of high temperature and high oxygen potential, impurities such as lead and zinc in the copper-nickel sulfide ore begin to volatilize and enter the flue gas.

[0043] The material that has undergone the smelting reaction in the primary smelting zone 1 falls directly into the secondary smelting zone 4. The secondary smelting zone is a smelting reaction zone with molten slag as the medium. Fuel and oxygen-enriched air required for complete smelting of raw materials are injected into the secondary smelting zone 4 through the spray gun 5 to supplement the heat. The nickel matte product obtained from the reaction in the secondary smelting zone enters the nickel matte layer and is periodically discharged through the nickel matte outlet 6 of the secondary smelting zone.

[0044] The molten slag enters the tertiary reduction smelting zone 8, which is also a molten pool reaction zone with molten slag as the medium. Fuel and oxygen-enriched air are injected into the tertiary reduction smelting zone 8 through the tertiary reduction smelting zone spray gun 9. The fuel and oxygen-enriched air are controlled to maintain a reducing atmosphere in the slag layer of the tertiary reduction smelting zone 8, reducing some of the metal oxides in the slag layer. Valuable metals such as nickel and copper are reduced and enter the nickel matte layer. The tertiary reduction smelting zone spray gun 9 is set at a position close to the surface of the molten pool, forming a strong stirring effect on the surface of the molten pool. Impurity elements such as lead and zinc are reduced and generate metallic substances with low boiling points, which are quickly separated from the molten pool.

[0045] After reduction and impurity removal, the slag enters the fourth-stage depletion smelting zone 13. A reducing agent and a sulfiding agent are added through the charging port 14 in the fourth-stage depletion smelting zone. These react with the peroxidized valuable metal oxides in the slag to undergo reduction and sulfidation chemical reactions, forming sulfides with relatively high density that separate from the slag. While the melt is heated by a controllable polarity electrode 15, electromagnetic stirring is used to promote the movement of the molten pool and improve the conditions for slag-matte separation. The coupling of chemical depletion by the reducing agent and the sulfiding agent with electromagnetic depletion generated by the controllable polarity electrode 15 improves the depletion efficiency, ultimately resulting in slag with extremely low nickel matte and valuable metal content, as well as flue dust rich in impurity elements.

[0046] In actual operation, the oxygen-enriched air concentration in this embodiment is 50-85%, the fuel used is a commonly used fuel in the field, such as pulverized coal or natural gas, and the reducing agent used is a commonly used reducing agent in the field, such as hydrogen.

[0047] The raw materials and auxiliary materials entering the furnace do not need to be dried or finely ground. The moisture content of the materials entering the furnace is ≤12%, and the ratio of auxiliary materials is based on Fe / SiO2 = 0.75-1.2 in the slag.

[0048] In this embodiment, the reaction temperatures of the primary spatial smelting zone 1, the secondary molten pool smelting zone 4, the tertiary reduction smelting zone 8, and the quaternary depletion smelting zone 13 are controlled continuously or in a gradient manner. The temperature in the primary spatial smelting zone 1 is 800-1200℃, the temperature in the secondary molten pool smelting zone 4 is 1200-1450℃, the temperature in the tertiary molten pool reduction smelting zone 8 is 1200-1450℃, and the temperature in the quaternary depletion smelting zone 15 is 1250-1550℃. Precisely controlling the temperature in each reaction zone is beneficial for fully controlling the reaction efficiency in each smelting zone, for clarifying and separating nickel matte from slag, and for enriching and recovering impurity metal elements.

[0049] In this embodiment, the nickel matte discharged from the secondary smelting zone at outlet 6 has a nickel matte grade (Ni+Cu) of 35-55%, and the nickel matte discharged from the quaternary depletion smelting zone at outlet 18 has a nickel matte grade (Ni+Cu) of 20-45%. The slag discharged from outlet 17 contains valuable metals with a content of Ni≤0.25% and Cu≤0.2%. The flue gas discharged from the multi-stage smelting zone's rising flue duct 10 contains 50-80% lead, zinc, and other impurities in the flue gas. The flue gas and dust temperature is usually 1000-1350℃. After being processed by the waste heat boiler and dust collection and purification system, the flue gas is sent to the acid production system for acid production. The collected flue gas is rich in lead, zinc, and other impurities. The lead, zinc, and other metal elements are recovered separately and are not returned to the smelting system for further processing.

[0050] Example 2 This embodiment provides a smelting method for copper-nickel sulfide ore using the method described in Example 1. The method uses high-grade magnesium copper-nickel sulfide minerals, the main chemical components and contents of which are shown in Table 1.

[0051] Table 1 Composition of copper-nickel sulfide ore In this embodiment, the above-mentioned high-grade magnesium copper-nickel sulfide minerals are used as raw materials and quartz is used as flux. The water content of the raw materials and flux is ≤10%; the flux ratio is Fe / SiO2=1.1.

[0052] The specific implementation steps of this embodiment are as follows: After the raw materials and fluxes are premixed according to the batching plan, they are added from the top of the primary space smelting zone 1 for primary smelting. The primary space smelting zone 1 is equipped with a primary space smelting zone spray gun 3, which is used to supplement fuel and oxygen-enriched air, increase the temperature of the smelting materials and control the oxygen potential. The central channel of the primary space smelting zone spray gun 3 is natural gas, and the outer channel is 50% oxygen-enriched air. The reaction temperature of the secondary smelting zone 4 is controlled at 1300℃, and the excess oxygen coefficient is adjusted. Some of the lead, zinc and arsenic in the raw materials are oxidized and gasified and enter the flue gas. The flue gas temperature is 1300℃.

[0053] The reacted materials in the primary smelting zone 1 fall directly into the secondary smelting zone 4 to form a molten slag layer. In the secondary smelting zone 4, a secondary smelting zone lance 5 is set up to inject fuel and oxygen-enriched air to completely melt the unreacted raw materials. The oxygen concentration of the lance used for raw material melting is 75%, and the fuel is natural gas and pulverized coal. The slag layer temperature is controlled at 1350℃. Nickel matte is separated from the slag in the secondary smelting zone 4 and sinks to the bottom to form a nickel matte layer. The nickel matte grade is controlled at (Ni+Cu) = 50%. It is periodically discharged from the furnace through the secondary smelting zone nickel matte outlet 6 at the bottom of its side wall. The slag enters the tertiary smelting zone 8 along the length of the furnace body for reduction smelting.

[0054] The reducing atmosphere is adjusted by adjusting the parameters of the spray gun 9 in the three-stage molten pool reduction zone. The central channel of the spray gun 9 in the three-stage molten pool reduction smelting zone is injected with pulverized coal with good reduction effect, while the outer channel is filled with oxygen-enriched air with a concentration of 70%. The oxygen-enriched air and excess pulverized coal burn in the molten pool to provide the heat required for the reduction reaction in the three-stage molten pool reduction smelting zone 8 and the heat required for the furnace to maintain thermal balance. The peroxide of nickel, copper, and impurities such as lead, zinc, and arsenic in the slag, along with some iron, are reduced to a metallic state by the pulverized coal.

[0055] The spray gun 9 in the three-stage molten pool reduction smelting zone is installed 250mm below the surface of the molten pool. The sprayed gas reacts with the gas produced by the molten pool, which strongly stirs the molten pool, causing the impurities such as metallic lead, zinc, and arsenic produced during reduction to volatilize into the flue gas. The flue gas dust collection system collects the flue gas dust rich in lead, zinc, and arsenic, while reducing the content of impurities in the nickel matte.

[0056] The nickel matte and slag produced in the tertiary molten pool reduction zone 8 flow along the length of the tertiary depletion smelting zone 13. Lump coal and high-sulfur copper-nickel sulfide ore with 28% sulfur content are added to the top of the tertiary depletion smelting zone 13 to reduce and sulfide the overoxidized valuable metals in the slag. A controllable polarity electrode 15 is installed in the tertiary depletion smelting zone 13 to heat the molten pool and periodically stir it with electromagnetic agitation. The slag settling and separation time in the tertiary depletion smelting zone 13 is controlled to be 120 min, the slag temperature is 1350℃, and the power supply load of the controllable polarity electrode 15 is 100 kVA / m. 2 After depletion, the molten slag is discharged from the furnace by overflow. The slag contains 0.25% nickel and 0.23% copper, with a nickel recovery rate of 95.87% and a copper recovery rate of 94.32%.

Claims

1. A metallurgical furnace for multi-stage smelting and depletion of copper-nickel sulfide ore, comprising a furnace body, characterized in that, The furnace body adopts an integrated structure, and its interior is provided with a primary space smelting zone (1), a secondary molten pool smelting zone (4), a tertiary molten pool reduction smelting zone (8), and a quaternary depletion smelting zone (13) arranged in a connected manner. The first-level space smelting zone (1) is equipped with several feeding nozzles (2) at the top for adding smelting materials and several first-level smelting zone spray guns (3) inside for injecting fuel and oxygen-enriched air. The secondary molten pool smelting zone (4) is located directly below the primary space smelting zone (1), and the two are connected. The secondary molten pool smelting zone (4) is equipped with several secondary smelting zone spray guns (5) that inject fuel and oxygen-enriched air into the molten pool, and a secondary smelting zone nickel matte discharge port (6) for discharging produced nickel matte. The three-stage molten pool reduction smelting zone (8) is located on one side of the two-stage molten pool smelting zone (4) along the length of the furnace body. The two are separated by the first water-cooled structural partition wall (7). A channel for the flow of molten material is provided below the first water-cooled structural partition wall (7). The three-stage molten pool reduction smelting zone (8) is equipped with several three-stage molten pool reduction smelting zone spray guns (9) that inject fuel and oxygen-enriched air into the molten pool. The fourth-level depletion smelting zone (13) is located on the other side of the third-level molten pool reduction smelting zone (8) along the length of the furnace body. The two are separated by the second water-cooled structural partition wall (12). A channel for the flow of melt is provided below the second water-cooled structural partition wall (12). The top of the fourth-stage depleted smelting zone (13) is provided with several controllable polarity electrodes (15), a fourth-stage depleted smelting zone feeding hole (14) for adding reducing agent and sulfiding agent, and a fourth-stage depleted smelting zone flue (16). The side is provided with a slag discharge port (17) and a fourth-stage depleted smelting zone nickel matte discharge outlet (18).

2. The metallurgical furnace according to claim 1, characterized in that, The bottoms of the first water-cooled structural partition wall (7) and the second water-cooled structural partition wall (12) are both immersed in the molten pool. Their depths are configured to allow the melt to flow through the channels at the bottom of the partition wall, while preventing unreacted materials or slag floating on the surface of the molten pool from crossing the partition wall into the next area.

3. The metallurgical furnace according to claim 1, characterized in that, The nickel matte discharge outlet (6) of the secondary smelting zone, the nickel matte discharge outlet (18) of the fourth-level depleted smelting zone, and the slag discharge outlet (17) adopt one or more combinations of low-mouth burn-out discharge, siphon discharge, or high-mouth overflow discharge.

4. The metallurgical furnace according to claim 1, characterized in that, The nickel matte discharge outlet (18) of the fourth-level depleted smelting zone and the nickel matte discharge outlet (6) of the second-level smelting zone are located at different positions at the bottom of the furnace body, and are used to discharge nickel matte products of different grades respectively.

5. The metallurgical furnace according to claim 1, characterized in that, The nozzle of the spray gun (9) in the three-stage molten pool reduction smelting zone is set at a position close to the molten pool surface to strongly stir the slag layer on the surface of the molten pool, promote the separation of the volatile metal substances generated by reduction from the molten pool into the flue gas, and form enrichment in the flue gas dust.

6. The metallurgical furnace according to claim 1, characterized in that, The primary space smelting zone (1) is equipped with a multi-stage smelting zone rising flue (10) for discharging flue gas, and it is located above the furnace body.

7. The metallurgical furnace according to claim 6, characterized in that, The multi-stage smelting zone rising flue (10) is symmetrically provided with several multi-stage smelting zone rising flue spray guns (11) on both sides, which are used to inject fuel and oxygen-enriched air into the flue to perform secondary combustion and heat up the flue gas.

Images