Side-blown plasma reinforced multi-metal composite melt reduction recovery method and reduction furnace

Abstract

The invention provides a side blowing type plasma reinforced multi-metal composite melt reduction recovery method and a reduction furnace, the reduction furnace comprises a molten pool and a plasma mechanism, a melt converging opening is formed in the upper portion of the molten pool applied to multi-metal composite melt reduction recovery, and a flue, a slag discharging opening and a siphon opening are formed in the side, away from the melt converging opening, of the molten pool; the flue, the slag discharge port and the siphon port are sequentially arranged from top to bottom; the plasma mechanism comprises a plasma torch, the plasma torch is provided with a blowing port, the blowing port extends into the molten pool from the side direction and is located in a reduction reaction area of the molten pool so as to provide lateral airflow for the reduction reaction area in the reduction reaction process, and the included angle alpha between the blowing direction of the blowing port and the horizontal plane is larger than or equal to-30 degrees and smaller than or equal to 30 degrees. The problems that the contact of the reducing agent is limited and the reaction kinetics is blocked due to adhesion of the high-zinc melt are solved from the source, and the reduction effect is optimized.

Description

Technical Field

[0001] The invention belongs to the technical field of valuable metal recovery, and particularly relates to a plasma side-blowing reduction furnace and application thereof. Background Art

[0002] Currently, high-grade primary lead and zinc ore resources are becoming increasingly depleted, and smelting raw materials are becoming increasingly complex. Valuable metals such as lead, zinc, and copper commonly coexist in minerals or secondary resources in the form of oxides or sulfides, exhibiting significant characteristics such as complex intercalation, close association, and difficulty in separation. To efficiently recover these metal resources, pyrometallurgical processes are commonly used in industry. Among these, traditional processes, such as blast furnace zinc smelting (ISP), are relatively mature, possessing a certain adaptability to raw materials and an industrial foundation. However, industrial practice, as well as thermodynamic and kinetic studies, have shown that in traditional pyrometallurgical processes such as ISP, multimetallic composite melts containing >15% Zn exhibit high melting points, poor fluidity, and low liquid zinc oxide activity. Their reduction process significantly lags behind that of metals such as copper and lead. In particular, in a lead-zinc-copper multimetallic system, the reduction order of metal oxides in the melt is typically: copper > lead > zinc. This significantly limits zinc reduction efficiency, making it difficult to fully recover some zinc, a key bottleneck restricting efficient smelting.

[0003] In addition, traditional processes mostly rely on surface energy supply and localized heating, lacking effective stirring and atmosphere control within the melt. This further limits the uniformity of the reduction reaction and the mass transfer rate of high-viscosity melts, hindering the full release of difficult-to-reduced metals. At the same time, with the green transformation of the lead and zinc smelting industry and the advancement of the "dual carbon" goals, a large amount of secondary resources such as lead-zinc smelting slag, electric furnace dust, oxide slag, scrap alloys, and electronic waste are in urgent need of resource utilization and high-value utilization. Existing processes still have problems with high energy consumption, low recovery rates, and poor adaptability in the efficient reduction and separation of such multi-metal oxides, and urgently need to be upgraded.

[0004] Therefore, there is an urgent need to develop a smelting technology that offers high thermal intensity, uniform airflow disturbance, and adaptability to the characteristics of high-ZnO melts and complex secondary resources. Based on this, the present invention provides a side-blown plasma-enhanced reduction device and its application method. By optimizing gas composition, lateral plasma airflow distribution, and slag system matching, it significantly improves the reduction reaction rate and metal recovery efficiency of the melt. This device is particularly suitable for the green and efficient smelting and resource recycling of high-zinc, high-viscosity, and complex multi-metal raw materials. Summary of the Invention

[0005] Aiming to solve the technical problem of the urgent need to improve the reduction reaction rate and metal recovery efficiency of high-zinc, high-viscosity, and complex multi-metal raw materials in the above-mentioned conventional technologies, the present invention provides a plasma side-blown reduction furnace for the reduction and recovery of multi-metal composite melts. The composition of the composite melt includes, by mass fraction, 15% to 40% zinc, 10% to 30% lead, 5% to 25% iron, 10% to 25% silicon, and 5% to 20% copper.

[0006] A melt inlet is provided at the top of the molten pool, and a flue, a slag discharge port and a siphon port are provided on a side of the molten pool away from the melt inlet, wherein the flue, the slag discharge port and the siphon port are arranged in sequence from top to bottom;

[0007] The plasma mechanism includes a plasma torch having a blowing port, which extends from the side into the interior of the molten pool and is located in the reduction reaction area of ​​the molten pool to provide a lateral airflow to the reduction reaction area during the reduction reaction process. The angle between the blowing direction of the blowing port and the horizontal is -30°≤α≤30.

[0008] Furthermore, the power of the plasma torch is 100-300kW, the angle between the blowing direction of the blowing port and the horizontal is -15°≤α≤30, and the gas volume in the plasma is 15-60m 3 / h.

[0009] Furthermore, the molten pool portion is further provided with an electromagnetic induction heating device, which is located at the bottom of the molten pool to supply heat to the composite melt in the molten pool.

[0010] Furthermore, the flue is connected to an external condensation facility.

[0011] The present invention provides a side-blowing plasma-enhanced reduction and recovery method for a multi-metal composite melt, which uses the plasma side-blowing reduction furnace described in any one of the above.

[0012] Further, including:

[0013] The molten pool contains a composite melt, which undergoes a reduction reaction under the stirring of the plasma gas sprayed from the side by the plasma mechanism to obtain an alloy phase, zinc vapor and slag; the plasma working medium of the plasma gas includes a reducing agent.

[0014] Furthermore, the composition of the composite melt includes, by mass fraction: 15% to 40% zinc; 10% to 30% lead; 5% to 20% copper; 5% to 25% iron; 10% to 25% silicon; and 5% to 20% calcium; the calcium-silicon ratio of the composite melt is 0.8 to 2.0, and the iron-silicon ratio is 0.2 to 1.0.

[0015] Furthermore, the reduction reaction lasts for 30 minutes to 90 minutes, and the reduction reaction temperature is 1100 to 1350°C.

[0016] Furthermore, the plasma working medium of the plasma-state gas also includes a protective agent; the reducing agent includes one or more of CO, H2, CH4, and carbon powder, and the protective agent includes Ar2 and / or N2; the volume ratio of the reducing agent to the protective agent is 5% to 40%, and the amount of the reducing agent added is 1.2 to 2.0 times the molar amount of the reducing agent required to reduce all the metal oxides to be reduced in the composite melt into metal elements.

[0017] Furthermore, the plasma torch is immersed in the composite melt, and the temperature of the blowing port of the plasma torch is 2000-3500°C.

[0018] Compared with the prior art, the present invention has at least the following advantages:

[0019] The present invention provides a plasma side-blowing reduction furnace that utilizes plasma enhancement measures in conjunction with molten pool smelting technology to specifically treat a composite melt having a zinc content of not less than 20%, thereby achieving thorough reduction of the composite melt. A plasma mechanism immersed in the composite melt generates a plasma jet that fully agitates the composite melt in the form of a high-temperature, high-velocity airflow. On the one hand, the plasma mechanism concentrates its energy to eject the high-temperature plasma jet. Due to the small cross-section and highly concentrated heat of the plasma jet, the metallic zinc in the composite melt is vaporized the moment it comes into contact with it. As the composition of the composite melt changes, the viscosity decreases and the fluidity increases, fundamentally resolving the issues of limited reducing agent contact and hindered reaction kinetics caused by the high viscosity of the composite melt, thereby optimizing the reduction effect. On the other hand, the reducing flame generated by the plasma mechanism generates plasma reducing active groups that undergo reduction reactions with oxides in the composite melt. While strengthening the chemical reaction process and lowering the reaction barrier, it also enhances molten pool blowing, significantly enhancing mass transfer, allowing the reduced gaseous products in the composite melt to escape quickly, allowing the alloy phase to aggregate and settle, and achieving excellent slag-metal separation.

[0020] In comparison, in the commonly used technologies, the reduction smelting process still has problems such as insufficient carbon combustion and low energy efficiency, and the added carbonaceous reducing agent floats on the surface of the molten pool and is difficult to enter the molten pool to participate in the reaction. Especially for composite melts with high viscosity, high melting point and poor fluidity, the above technical problems are even more difficult under the processing challenges of composite melts. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0022] Figure 1 This is a structural schematic diagram of a plasma side-blown reduction furnace in one embodiment of the present invention, wherein 1 is a melt inlet, 2 is a closed feeding port, 3 is an electromagnetic induction heating device, 4 is a flue, 5 is a slag discharge port, 6 is a siphon port, and 7 is a plasma mechanism. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0024] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0025] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those in the examples of the present invention may also be used to implement the present invention.

[0026] The present invention utilizes plasma strengthening means in conjunction with molten pool smelting technology to specifically process a composite melt with a zinc content of 15 to 40%.

[0027] Plasma metallurgy is an advanced metallurgical technology that uses high-temperature plasma as a heat source. It is currently used in the smelting of high-melting-point metals such as titanium and tantalum, as well as in metal refining. Plasma metallurgy has the following advantages: High thermal performance: The plasma has very high temperatures, easily reaching 5,000-20,000°C internally and 2,000-3,500°C at the nozzle; Energy concentration: Due to the small cross-section of the plasma jet, heat is highly concentrated, which helps improve heating efficiency and reduce energy loss; High chemical activity: The gas particles in the plasma have high energy, which can promote chemical reactions and help achieve the reduction, oxidation, and alloying of metals; Controllable reaction atmosphere: The composition and pressure of the plasma gas source can be adjusted to meet the smelting requirements of different metals, achieving precise control of the atmosphere; Adjustable power: The power of the plasma metallurgical equipment can be adjusted according to the needs of the smelting process, providing greater flexibility; Environmental friendliness: The plasma metallurgical process can achieve environmental control and reduce the emission of harmful gases, meeting the environmental protection requirements of modern industry.

[0028] In the commonly used molten pool smelting technology, lead and zinc ore are usually sintered and desulfurized to form sintered blocks mixed with coke. The sintered blocks are then placed in a molten pool reduction furnace. Valuable metals such as lead, zinc, and copper melt into the melt in the form of metal oxides, and the valuable metals are recovered through a reduction smelting process. However, the reduction smelting process often suffers from problems such as insufficient carbon combustion, low energy efficiency, and the added carbonaceous reducing agent floating on the surface of the molten pool and having difficulty entering the interior of the molten pool to participate in the reaction. For example, the Kifset furnace uses a layer of hot coke floating on the surface of the melt to reduce the material passing through the coke layer, but the coke layer has little effect on reducing the unreduced metal oxides that have passed through the coke layer and entered the molten pool.

[0029] Composite melts with Zn contents greater than 15% exhibit high viscosity, a high melting point (zinc oxide's melting point is as high as 1975°C), and poor fluidity. This further highlights the technical barriers to incomplete reduction of high-zinc materials using conventional molten pool smelting techniques due to insufficient contact with the reducing agent and its unique physical properties. Therefore, it is necessary to optimize the reduction effect of composite melts through technological improvements.

[0030] In order to solve the technical problems of the composite melt physical properties (poor fluidity, high melting point) and incomplete reduction caused by insufficient contact of the reducing agent in the above-mentioned common technologies, Figure 1 As shown, the present invention provides a plasma side-blowing reduction furnace, including a plasma mechanism 7 and a molten pool, which is used for the reduction and recovery of a multi-metal composite melt. The composition of the composite melt includes, by mass fraction, 15% to 40% zinc, 10% to 30% lead, 5% to 25% iron, 10% to 25% silicon, and 5% to 20% copper. Within this composition range, the advantages of the side-blowing plasma smelting technology can be fully utilized, promoting the efficient separation and recovery of multiple valuable metals.

[0031] In some embodiments, the composition of the composite melt may include, by mass, 20% to 40% zinc, 10% to 20% lead, 15% to 25% iron, 10% to 25% silicon, and 5% to 20% copper. In some specific embodiments, the composition of the composite melt may include, by mass, 30% to 40% zinc, 10% to 20% lead, 15% to 25% iron, 10% to 25% silicon, and 5% to 20% copper. The composite melt may also include 5% to 15% calcium. In some embodiments, the composite melt may also include 5% to 15% calcium.

[0032] The plasma side-blowing reduction furnace provided by the present invention is suitable for processing larger molten pools, multi-metal systems, and complex ores that require uniform stirring. The side-blowing technology can provide a relatively uniform airflow distribution, ensuring the uniformity of the reaction.

[0033] In some embodiments, the source of the multi-metal composite melt may include mineral raw materials with relatively complex compositions and the coexistence of multiple metals and / or secondary metallurgical resources. Mineral raw materials with relatively complex compositions and the coexistence of multiple metals include lead-zinc sulfide ores (e.g., sphalerite, galena), lead-zinc oxide ores, and copper-lead-zinc polymetallic ores, typically found in Lanping, Yunnan, China, the Yulong mining area in Tibet, the Huoshaoyun deposit in Xinjiang, the Broken Hill deposit in Australia, as well as Peru and Canada. Secondary metallurgical resources may include lead-zinc smelting slag (ISP slag, bottom-blown slag), steel smelting dust (electric furnace dust, converter mud), scrap zinc alloy, zinc ash, scrap lead-acid battery plates, and electronic waste (e.g., scrap circuit boards).

[0034] In some embodiments, the source of the multi-metal composite melt may also include heavy metal-containing solid waste materials, which may include but are not limited to lead-zinc oxide materials and urban minerals, lead-zinc-copper sulfide ore sintered blocks, lead-zinc-copper sulfide ore roasted sand, waste circuit boards, etc.

[0035] In some embodiments, the composite melt may further include a flux, and the types of the flux may include limestone, silicon dioxide, etc., to adjust the calcium-silicon ratio of the composite melt to 0.4-1.0 and the iron-silicon ratio to 1.0-1.5.

[0036] In the present invention, a melt inlet 1 is provided at the top of the molten pool, and a flue 4, a slag discharge port 5, and a siphon port 6 are provided on a side of the molten pool away from the melt inlet 1. The flue 4, the slag discharge port 5, and the siphon port 6 are arranged sequentially from top to bottom. It should be noted that the flue 4, the slag discharge port 5, and the siphon port 6 do not need to be arranged in the same vertical line. They can be flexibly and reasonably arranged in an interlaced manner based on factors such as actual process requirements, furnace structural characteristics, and operational convenience.

[0037] In some embodiments, the molten pool is further provided with an electromagnetic induction heating device 3 , which may be located at the bottom of the melt to supply heat to the composite melt in the molten pool.

[0038] In some embodiments, the flue 4 is connected to an external condensation facility.

[0039] In some embodiments, a sealed charging port 2 may be opened on the top or upper portion of the side wall of the plasma side-blowing reduction furnace.

[0040] In the present invention, the plasma mechanism 7 includes a plasma torch having a blowing port, which extends from the side into the interior of the molten pool and is located in the reduction reaction area of ​​the molten pool to provide a lateral airflow to the reduction reaction area during the reduction reaction process. The angle between the blowing direction of the blowing port and the horizontal is -30°≤α≤30.

[0041] In some embodiments, the plasma torch may include a lifting device that descends below the surface of the molten pool to further enhance mass and heat transfer in the molten pool by injecting inert gas and plasma gas into the molten pool. Oxidizing components in the molten pool react chemically with the carbon monoxide plasma.

[0042] In some embodiments, the plasma torch includes a cathode, an anode, a water inlet assembly, a water outlet assembly, a circulating water control assembly, and a power control assembly. A cooling water assembly cools the cathode and anode to prevent high-temperature electrode ablation. The plasma torch is rectangular and can be adjusted for plasma power, the number of torches, powder feed rate, and furnace volume, enabling adaptable, large-scale production.

[0043] In some embodiments, the power of the plasma torch can be 100-300 kW, and the angle between the blowing direction of the blowing port and the horizontal can be -15°≤α≤30. In some embodiments of the present invention, the number of plasma torches can be 3-4, and the cross-sectional area of ​​each plasma torch is 10-120 cm 2 .

[0044] In some embodiments, the gas volume in a single plasma torch can be 15 to 60 m 3 / h.

[0045] In the present invention, the overall height of the plasma side-blowing reduction furnace can be 2 to 5 meters, and the diameter can be 3 to 5 meters.

[0046] In a specific embodiment of the present invention, the plasma side-blowing reduction furnace can be used as follows: solid waste materials containing heavy metals such as lead, zinc, copper, and iron are dried and then mixed, and then melted to form a liquid heavy metal melt, which is then added to the plasma side-blowing reduction furnace through a closed continuous sub-melt inlet 1; the heavy metal solid waste materials and flux are mixed in proportion and then added to the liquid heavy metal melt through a closed feeding port to form a composite melt; the plasma mechanism 7 is evenly distributed on the side of the furnace body, and the plasma torch excites the carrier to form plasma active substances, thereby reducing the reaction barrier and accelerating the reaction speed; an electromagnetic induction coil is used to assist in heating at the bottom of the furnace body to maintain the molten pool temperature in the enhanced furnace at 1100-1350°C; the slag shape is reasonably adjusted to control the plasma enhanced atmosphere, and after a reaction time of 30-90 minutes, the reacted alloy phase is separated through the siphon port 6, and the slag phase is discharged through the slag discharge port 5, and the alloy phase is subsequently separated and purified.

[0047] The present invention provides an application of the plasma side-blown reduction furnace as described above in reducing and recovering valuable metals in a composite melt, comprising the steps of: the molten pool contains a composite melt, and the composite melt undergoes a reduction reaction under the stirring of the plasma gas blown by the plasma mechanism 7 to obtain an alloy phase, zinc vapor and slag.

[0048] In the present invention, the source of the multi-metal composite melt may include mineral raw materials with relatively complex compositions and the coexistence of multiple metals and / or secondary metallurgical resources. The mineral raw materials with relatively complex compositions and the coexistence of multiple metals may include lead-zinc sulfide ores (such as sphalerite and galena), lead-zinc oxide ores, and copper-lead-zinc polymetallic ores, typically found in Lanping, Yunnan, China, the Yulong mining area in Tibet, the Huoshaoyun deposit in Xinjiang, the Broken Hill deposit in Australia, as well as Peru and Canada. Secondary metallurgical resources may include lead-zinc smelting slag (ISP slag, bottom-blown slag), steelmaking dust (electric furnace dust, converter mud), scrap zinc alloy, zinc ash, scrap lead-acid battery plates, and electronic waste (such as scrap circuit boards).

[0049] In some embodiments, the source of the multi-metal composite melt may also include heavy metal-containing solid waste materials, which may include but are not limited to lead-zinc oxide materials and urban minerals containing heavy metals.

[0050] In some embodiments, the composition of the composite melt includes, by mass fraction, 15% to 40% zinc, 10% to 30% lead, 5% to 25% iron, 10% to 25% silicon, and 5% to 20% copper.

[0051] In some embodiments, the calcium-silicon ratio of the composite melt can be controlled to be 0.4-1.0, and the iron-silicon ratio can be controlled to be 1.0-1.5.

[0052] In some specific embodiments, the application of a plasma side-blown reduction furnace in reducing and recovering valuable metals in a composite melt is practiced on a laboratory scale, comprising the following steps:

[0053] (1) Start the nitrogen generator and CO controller, add raw materials to the crucible, close the chamber, open the vent valve, start the nitrogen purge device, keep the atmosphere in the plasma furnace in an inert state, start the electromagnetic induction heating device 3, and heat the furnace to 1100-1350℃.

[0054] (2) According to the temperature of the molten liquid in the furnace, the plasma gun advance distance is controlled. The high-zinc material is heated by the induction coil, melted, and then subjected to the CO plasma torch for enhanced reduction spraying to produce alloys such as lead, copper, antimony, bismuth, gold, and silver. Impurities such as gangue in the melt form slag.

[0055] (3) The present invention utilizes CO plasma blowing to enhance the molten pool blowing, stir the molten pool, and strengthen mass transfer and heat transfer, so that the gaseous products reduced in the composite melt can escape quickly, and the alloy phase after reduction is strengthened to aggregate and settle, thereby forming a good separation between slag and metal.

[0056] In the present invention, the reduction reaction may be carried out for 30 to 90 minutes, and the reduction reaction temperature may be 1100 to 1350°C.

[0057] In the present invention, the plasma working medium of the plasma-state gas includes a reducing agent and a protective agent, wherein the reducing agent includes one or more of CO, H2, CH4, and carbon powder, and the protective agent includes Ar2 and / or N2; the flow ratio of the reducing agent to the protective agent can be 5% to 40%.

[0058] In some embodiments, a reducing flame can be formed using H2 or CO, while a neutral flame can be formed using Ar2 or N2. This generates plasma to enhance the reduction of active groups and strengthen the chemical reaction process. Specifically, when the reducing agent includes CO, CO absorbs energy through rotation, vibration, dissociation, and ionization when interacting with high-energy electrons within the plasma torch, forming excited species such as CO, CI, C II, and O II, thereby enhancing the melt reduction effect.

[0059] In some specific embodiments of the present invention, a gas distribution system can be used to mix a reducing agent and a protective agent, and then a plasma torch can be used to generate an arc to ionize the reducing agent and protective agent to generate a plasma-state substance, which then undergoes a reduction reaction with the composite melt. Specifically, a DC power supply generates a high voltage current, and the reducing agent and protective agent are instantly broken down by the arc between the cathode and anode, generating a high-temperature plasma-state substance. A high-speed airflow is then injected into the melt within the spray gun, providing high temperature and activated radicals. The ionized carbon monoxide plasma acts as a reducing agent to undergo a reduction reaction with the oxides in the composite melt, and the lead and zinc are volatilized to the gas phase for recovery. The iron is reduced to liquid iron and discharged through a siphon port 6. Impurities and residual oxide slag in the composite melt float on the surface in a molten state and are discharged through a slag discharge port 5.

[0060] In the present invention, the temperature of the injection port area of ​​the plasma torch is as high as 2500-3000°C.

[0061] In some embodiments, a reducing agent, such as carbon powder or CO, can be introduced into the melt using plasma gas as a carrier. The reducing agent provides heat and a reducing atmosphere within the melt, while an electromagnetic induction coil at the bottom maintains the heat of the melt pool, enhancing the reduction of the melt pool. The melt temperature within the melt pool is 1100-1350°C, completing the reduction of oxides such as lead, zinc, and copper, and completing the slag formation reaction.

[0062] Compared to traditional solid-state carbon-based reduction and gas injection reduction, the present invention provides a plasma-enhanced composite melt reduction method for recovering valuable metals. This method fully utilizes plasma-enhanced chemical reactions and the sensible heat of high-temperature liquid melts to explore and optimize the process, laying the foundation for subsequent continuous and large-scale production. This method allows for rapid recovery of valuable metals from slag. Compared to conventional pulverized coal injection, coke filter layer reduction, and gas-solid reduction techniques, the present invention achieves lower valuable metal content in the slag after reduction and a higher overall recovery rate for valuable metals.

[0063] In order to facilitate those skilled in the art to further understand the present invention, examples are given below:

[0064] Example 1

[0065] S1. Oxidized slag from a domestic lead-zinc smelter is mixed with flux (including limestone and silica) in appropriate proportions, and the slag is adjusted to have a calcium-silicon ratio (CaO / SiO2) of 0.8 and an iron-silicon ratio (FeO / SiO2) of 1.2. After drying, the slag is continuously added to the furnace through a sealed feed port 2. The molten pool is heated to 1350°C using an electromagnetic induction heating device 3, and melted to form a composite melt. The composite melt comprises, by mass, 35% zinc, 12% lead, 5% copper, 20% iron, 15% silicon, 8% calcium, and 5% other ingredients.

[0066] Plasma torch configuration: 3 plasma torches are evenly distributed on the side wall, and the plasma torches are distributed below the composite melt surface. The power of a single torch is 100kW, and the cross-sectional area is 80cm. 2 , the angle α between the plasma torch nozzle and the horizontal direction is 15°;

[0067] Gas medium: CO and N2 are mixed at a volume ratio of 20%, and the working medium flow rate in a single plasma torch is 20 cubic meters per hour;

[0068] Electromagnetic induction heating power: 200kW, maintaining the molten pool temperature at 1350°C.

[0069] S2. Start the plasma torch and adjust the spray gun to below the surface of the molten pool. The CO / N2 mixed gas is ionized to generate a highly active plasma. The plasma jet stirs the molten pool to promote the reduction reaction of ZnO, PbO and CO. The reaction time is 1 hour. The amount of CO used is 1.2 times the molar amount of the reducing agent required to reduce all the metal oxides to be reduced in the composite melt to metal elements.

[0070] S3. After reduction, an alloy phase, a gas phase, and a reduced slag phase are generated. The alloy phase (containing 85% Pb, 8% Cu, and 0.5% Ag) is discharged through a siphon port 6 and forms an alloy ingot after cooling. Zinc vapor is introduced into a condenser through a flue 4 for recovery, with a zinc recovery rate of 98.5%. The reduced slag phase (containing Zn ≤ 0.5% and Pb ≤ 0.3%) is discharged through a slag discharge port 5 and forms a glassy, ​​harmless slag after cooling.

[0071] Result analysis: Comprehensive metal recovery rate: Zn 99.2%, Pb 97.8%, Cu 95.5%;

[0072] Energy consumption: 35% lower than that of the traditional coke reduction method in Comparative Example 1, and CO energy utilization rate reaches 75%.

[0073] Example 2

[0074] Compared with Example 1, other conditions in Example 2 remain unchanged, and only the reducing species in the plasma working medium is adjusted from CO to carbon powder.

[0075] S1. Oxidized slag from a domestic lead-zinc smelter is mixed with flux (including limestone and silica) in appropriate proportions, and the slag is adjusted to have a calcium-silicon ratio (CaO / SiO2) of 0.8 and an iron-silicon ratio (FeO / SiO2) of 1.2. After drying, the slag is continuously added to the furnace through a sealed feed port 2. The molten pool is heated to 1350°C using an electromagnetic induction heating device 3, and melted to form a composite melt. The composite melt comprises, by mass, 35% zinc, 12% lead, 5% copper, 20% iron, 15% silicon, 8% calcium, and 5% other ingredients.

[0076] Plasma torch configuration: 3 plasma torches are evenly distributed on the side wall, and the plasma torches are distributed below the composite melt surface. The power of a single torch is 100kW, and the cross-sectional area is 80cm. 2 , the angle α between the plasma torch nozzle and the horizontal direction is 15°;

[0077] The gas medium is N2 as the working medium, and the working medium flow rate in a single plasma torch is 15 cubic meters per hour;

[0078] Electromagnetic induction heating power: 200kW, maintaining the molten pool temperature at 1350°C.

[0079] S2. Start the plasma torch and adjust the spray gun to below the surface of the molten pool. The carbon powder / N2 mixed system is ionized to generate a highly active plasma. The plasma jet stirs the molten pool to promote the reduction reaction of ZnO, PbO and CO. The reaction time is 1 hour. The amount of carbon powder used is 1.5 times the molar amount of the reducing agent required to reduce all the metal oxides to be reduced in the composite melt to metal elements.

[0080] S3. After reduction, an alloy phase, a gas phase, and a reduced slag phase are generated. The alloy phase (containing 85% Pb, 8% Cu, and 0.5% Ag) is discharged through a siphon port 6 and forms an alloy ingot after cooling. Zinc vapor is introduced into a condenser through a flue 4 for recovery, with a zinc recovery rate of 98.5%. The reduced slag phase (containing Zn ≤ 0.5% and Pb ≤ 0.3%) is discharged through a slag discharge port 5 and forms a glassy, ​​harmless slag after cooling.

[0081] Result analysis: Comprehensive metal recovery rate: Zn 99.2%, Pb 97.8%, Cu 95.5%;

[0082] Energy consumption: 35% lower than traditional coke reduction method, and the plasma torch energy utilization rate reaches 75%.

[0083] Comparative Example 1

[0084] In this comparative example, other conditions remain unchanged, and the plasma side-blowing reduction method is adjusted to traditional coke reduction.

[0085] S1. First, oxidized slag from a domestic lead-zinc smelter (composition by mass: 35% zinc, 12% lead, 5% copper, 20% iron, 15% silicon, 8% calcium, and 5% other) was mixed with flux (including limestone and silica) in appropriate proportions. The slag was adjusted to have a calcium-silicon ratio (CaO / SiO2) of 0.8 and an iron-silicon ratio (FeO / SiO2) of 1.2.

[0086] S2. Blast furnace reduction was performed, with coke (85% carbon content) as the reducing agent, at a coke-to-ore mass ratio of 1:3. The furnace temperature was maintained by coke combustion, fluctuating between 1200°C and 1400°C. The reduction lasted 3 hours, with the coke floating on the surface of the molten pool. Only surface oxides participated in the reaction, leaving ZnO and PbO in the deeper layers incompletely reduced.

[0087] S3. After reduction, an alloy phase, a gas phase, and a reduced slag phase are generated. The alloy phase contains 70% Pb, 5% Cu, and 0.2% Ag, with a zinc recovery rate of 82% (some zinc remains in the slag due to incomplete reduction). The slag contains 6.5% Zn and 2.1% Pb, requiring secondary treatment. The exhaust gas contains a high concentration of CO2 and trace amounts of SO2 (due to coke sulfur).

[0088] Comparative Example 2

[0089] Compared with Example 1, other conditions remain unchanged, only the plasma step is eliminated, and the reducing agent is blown into the composite melt in the form of ordinary side blowing.

[0090] S1. Oxidized slag from a domestic lead-zinc smelter is mixed with flux (including limestone and silica) in appropriate proportions, and the slag is adjusted to have a calcium-silicon ratio (CaO / SiO2) of 0.8 and an iron-silicon ratio (FeO / SiO2) of 1.2. After drying, the slag is continuously added to the furnace through a sealed feed port 2. The molten pool is heated to 1350°C using an electromagnetic induction heating device 3, and melted to form a composite melt. The composite melt comprises, by mass, 35% zinc, 12% lead, 5% copper, 20% iron, 15% silicon, 8% calcium, and 5% other ingredients.

[0091] Electromagnetic induction heating power: 200kW, maintaining the molten pool temperature at 1350°C.

[0092] S2. CO is blown into the molten pool in the form of ordinary side blowing to promote the reduction reaction of ZnO, PbO and CO. The reaction time is 2 hours. The amount of CO used is 1.2 times the molar amount of reducing agent required to reduce all the metal oxides to be reduced in the composite melt to metal elements.

[0093] S3. After reduction, an alloy phase, a gas phase, and a reduced slag phase are generated. The alloy phase (containing 85% Pb, 8% Cu, and 0.5% Ag) is discharged through a siphon port 6 and forms an alloy ingot after cooling. Zinc vapor is introduced into a condenser for recovery through a flue 4, with a zinc recovery rate of 95.3%. The reduced slag phase (containing Zn ≤ 2.5% and Pb ≤ 1.2%) is discharged through a slag discharge port 5 and forms a glassy, ​​harmless slag after cooling. The reduction potential energy of unionized CO is insufficient (ΔG increases by 15%), and the viscosity of the FeO-SiO2-CaO slag phase increases, hindering the sedimentation of metal particles. The reaction kinetics are slow, and the reduction time is prolonged.

[0094] Result analysis: Comprehensive metal recovery rate: Zn 95.3%, Pb 90.1%, Cu 88.5%%;

[0095] Energy consumption: Ordinary side-blowing gas is unevenly dispersed, and the CO energy utilization rate is only 65%.

[0096] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A plasma side-blowing reduction furnace, characterized in that: The invention comprises a molten pool and a plasma mechanism, and is applied to the reduction recovery of a multi-metal composite melt, wherein the composition of the composite melt comprises, by mass fraction, 15% to 40% zinc, 10% to 30% lead, 5% to 25% iron, 10% to 25% silicon, and 5% to 20% copper; A melt inlet is provided at the upper portion of the molten pool, and a flue, a slag discharge port and a siphon port are provided on a side of the molten pool away from the melt inlet, wherein the flue, the slag discharge port and the siphon port are arranged in sequence from top to bottom; The plasma mechanism includes a plasma torch having a blowing port, which extends from the side into the interior of the molten pool and is located in the reduction reaction area of ​​the molten pool to provide a lateral airflow to the reduction reaction area during the reduction reaction process. The angle between the blowing direction of the blowing port and the horizontal is -30°≤α≤30.

2. The plasma side-blowing reduction furnace according to claim 1, characterized in that: The power of the plasma torch is 100-300 kW, and the angle between the blowing direction of the blowing port and the horizontal is -15°≤α≤30.

3. The plasma side-blowing reduction furnace according to claim 1, characterized in that: The molten pool portion is further provided with an electromagnetic induction heating device, which is located at the bottom of the molten pool to supply heat to the composite melt in the molten pool.

4. The plasma side-blowing reduction furnace according to claim 1, characterized in that: The flue is externally connected to a condensation facility.

5. A method for reducing and recovering a multi-metal composite melt by side-blowing plasma enhancement, characterized in that: A plasma side-blowing reduction furnace according to any one of claims 1 to 4 is used.

6. The side-blown plasma-enhanced reduction and recovery method of a multi-metal composite melt according to claim 5, characterized in that: include: The molten pool contains a composite melt, which undergoes a reduction reaction under the stirring of the plasma gas sprayed from the side by the plasma mechanism to obtain an alloy phase, a gas phase and a reduced slag phase; the plasma working medium of the plasma gas includes a reducing agent.

7. The side-blown plasma-enhanced reduction and recovery method of a multi-metal composite melt according to claim 6, characterized in that: Calculated by mass fraction, the composition of the composite melt includes: 15% to 40% zinc; 10% to 30% lead; 5% to 20% copper; 5% to 25% iron; 10% to 25% silicon; and 5% to 20% calcium. The calcium-silicon ratio of the composite melt is 0.8 to 2.0, and the iron-silicon ratio is 0.2 to 1.

0.

8. The side-blown plasma-enhanced reduction and recovery method of a multi-metal composite melt according to claim 6, characterized in that: The reduction reaction lasts for 30 to 90 minutes, and the reduction reaction temperature is 1100 to 1350° C.

9. The side-blown plasma-enhanced reduction and recovery method of a multi-metal composite melt according to claim 6, characterized in that: The plasma working medium of the plasma gas also includes a protective agent; the reducing agent includes one or more of CO, H2, CH4, and carbon powder, and the protective agent includes Ar2 and / or N2; the volume ratio of the reducing agent to the protective agent is 5% to 40%; the amount of the reducing agent added is 1.2 to 2.0 times the molar amount of the reducing agent required to reduce all the metal oxides to be reduced in the composite melt into metal elements.

10. The side-blown plasma-enhanced reduction and recovery method of a multi-metal composite melt according to claim 6, characterized in that: The plasma torch is immersed in the composite melt, and the temperature of the blowing port of the plasma torch is 2000-3500°C.

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