Method for producing zinc oxide through reduction recovery of zinc leaching residues and zinc oxide

Abstract

The invention provides a method for producing zinc oxide through reduction and recovery of zinc leaching residues and zinc oxide. The method comprises the steps that S1, the zinc leaching residues are sintered and pelletized, and zinc residue particles with the particle size being 1-3 cm are obtained; s2, biomass and zinc slag particles are mixed according to the weight ratio of 1: (1-3), and a mixed product is obtained; and S3, the mixed product is subjected to smelting treatment, and slag and zinc oxide after reaction are obtained. According to the method, the zinc leaching residues are reduced and recovered with low energy consumption, low cost, low CO2 emission and high recovery rate on the basis of biomass serving as a reducing agent, and the high-purity zinc oxide product is prepared. And in the reduction recovery process, coke or coal does not need to be adopted, meanwhile, acid leaching is not needed, and waste liquid and leaching residues are not generated.

Description

Technical Field

[0001] The present invention relates to the field of zinc leaching residue recovery, and in particular to a method for producing zinc oxide by reducing and recovering zinc leaching residue, and the zinc oxide. Background Art

[0002] Zinc is an important nonferrous metal with extensive applications in construction, infrastructure, and new energy. Currently, zinc smelting primarily utilizes hydrometallurgical processes, which produce large quantities of zinc leaching residue, a hazardous waste. Pyrometallurgical methods for treating zinc leaching residue primarily include continuous blowing in a fuming furnace and volatilization in a rotary kiln.

[0003] The above method requires the addition of coke or coal as a reducing agent, which results in high energy consumption, cost and CO2 emissions. For example, CN113846234B is a rotary kiln volatilization treatment method for high-silicon zinc leaching slag, which mixes zinc leaching slag, coke and calcium-containing substances evenly, and then adds them to a rotary kiln for smelting. The temperature of the high-temperature reaction zone in the kiln is 1150-1250°C, and the coke is commercial gasification coke powder or metallurgical coke. Zinc oxide smoke is produced at the tail of the kiln, and kiln slag is produced at the head of the kiln. However, the rotary kiln volatilization treatment requires the addition of a large amount of coke as a reducing agent, which increases energy consumption and cost, and CO2 emissions also increase; at the same time, it uses a rotary kiln for volatilization treatment, which is prone to the phenomenon of rotary kiln ringing, reducing treatment efficiency. The continuous blowing process of the fuming furnace (Shen Lijun, Li Bo, Lei Dejun. Research on the production of zinc oxide by continuous blowing of zinc slag fuming furnace [J]. Yunnan Metallurgy, 2005, 34(5):17-23) is to mix zinc leaching slag, pulverized coal or other reducing agents with air and then blow them into the fuming furnace. The combustion of pulverized coal produces a large amount of heat and carbon monoxide, which keeps the furnace at a high temperature and a certain reducing atmosphere. The metal oxides in the slag are reduced to metal vapor and volatilize. However, this method, i.e. the continuous blowing process of the fuming furnace, also requires the addition of a large amount of pulverized coal as a reducing agent, which increases energy consumption and cost, and also increases CO2 emissions. The process of acid leaching to extract zinc from zinc leaching slag (Guo Jiandong, Ou Haitao, Wang Minjie et al. Research on the recovery process of valuable metals from zinc smelting slag [J]. Gold, 2024, 45(02):57-60+67.) provides a solution for treating zinc leaching slag with sulfuric acid leaching. Through acid leaching to enhance leaching, the zinc leaching rate can reach more than 90%. However, the direct sulfuric acid leaching process consumes a large amount of sulfuric acid, resulting in high production costs and heavy pressure on equipment operation and maintenance. At the same time, the sulfuric acid leaching zinc extraction process produces a large amount of waste liquid and leaching residue, polluting the environment.

[0004] Regarding the selection of reducing agents, CN117604238A provides a method for treating zinc-containing solid waste by reducing and roasting biomass. This method uses agricultural and forestry biomass as a reducing agent to extract zinc from zinc-containing solid waste. However, this method converts the difficult-to-dissolve zinc ferrites in the zinc leaching residue into zinc oxide and highly magnetic magnetite. Only zinc-containing leachate and magnetite concentrate are obtained through acid leaching and magnetic separation, and the zinc oxide product is not recovered. Furthermore, the acid leaching step involves high acid consumption, resulting in high production costs and heavy equipment operation and maintenance. Furthermore, the method produces a large amount of waste liquid and leaching residue, polluting the environment.

[0005] At the same time, large-scale zinc oxide production currently faces bottlenecks. Commonly used production methods include zinc sulfate roasting, zinc sulfate wet leaching, and zinc sulfate evaporation. All of these production methods have significant drawbacks. The zinc sulfate roasting method, due to the low zinc content in the zinc sulfate leaching residue and the high cadmium and lead content in the zinc sulfate leaching residue, results in a complex process flow, severe equipment corrosion, and difficulty in controlling product quality. The zinc sulfate wet leaching method has a relatively short process flow for producing zinc oxide, but the leaching residue contains large amounts of impurities such as sulfuric acid, iron, manganese, cadmium, and lead, making it difficult to remove impurities and resulting in a low zinc oxide recovery rate. The zinc sulfate evaporation method can produce scaling substances such as calcium sulfate and magnesium sulfate during the evaporation process, resulting in severe equipment corrosion and difficulty in controlling product quality.

[0006] Based on this, how to provide a method for directly reducing zinc leaching residue to recover zinc oxide without introducing a large amount of coke or coal as a reducing agent and without introducing an acid leaching step, so as to prepare a high-purity zinc oxide product with a high recovery rate, is one of the important technical problems that need to be solved in this field. Summary of the Invention

[0007] The main purpose of the present invention is to provide a method for producing zinc oxide by reducing and recovering zinc leaching residue, and zinc oxide, so as to solve the problem in the prior art that it is difficult to reduce and recover zinc leaching residue with a high recovery rate and prepare a high-purity zinc oxide product without introducing a large amount of coke or coal and without involving an acid leaching step.

[0008] To achieve the above-mentioned object, a first aspect of the present invention provides a method for producing zinc oxide by reducing and recovering zinc leaching residue, comprising: step S1, sintering the zinc leaching residue to form pellets to obtain zinc slag particles with a particle size of 1 cm to 3 cm; step S2, mixing biomass and zinc slag particles in a weight ratio of 1: (1 to 3) to obtain a mixed product; step S3, smelting the mixed product to obtain reaction slag and zinc oxide.

[0009] Furthermore, the zinc leaching residue includes, by weight, 30 to 35 parts of zinc, 11 to 15 parts of iron, 10 to 15 parts of silicon, 5 to 7 parts of calcium, 3 to 5 parts of magnesium, and 0.3 to 1.0 parts of potassium.

[0010] Furthermore, in step S1, the particle size of the zinc slag particles is 1 cm to 1.5 cm; preferably, the temperature of sintering and pelletizing is 800°C to 1000°C.

[0011] Furthermore, in step S2, the biomass and the zinc slag particles are mixed in a weight ratio of 1: (1.5-2.0) to obtain a mixed product.

[0012] Furthermore, the biomass is selected from one or more of straw, poplar wood chips, pine wood chips and eucalyptus wood chips, preferably poplar wood chips, and the carbon content of the poplar wood chips is 30 wt% to 50 wt%.

[0013] Furthermore, in step S3, the smelting process includes a first smelting and a second smelting performed sequentially, and: the temperature of the first smelting is 400°C to 500°C; the temperature of the second smelting is 1100°C to 1300°C.

[0014] Furthermore, the time of the first smelting and the second smelting are each independently 0.5 h to 3.0 h, and the heating rate is each independently 10° C. / min to 30° C. / min.

[0015] Furthermore, the zinc content in the slag after the reaction is 1 wt% to 4 wt%.

[0016] A second aspect of the present invention provides zinc oxide, which is prepared by the above-mentioned method of producing zinc oxide by reducing and recovering zinc leaching residue.

[0017] Furthermore, the zinc content in the zinc oxide is 72 wt% to 78 wt%.

[0018] The technical solution of the present invention, using biomass as a reducing agent, achieves the reduction and recovery of zinc leaching residue with low energy consumption, low cost, low CO2 emissions, and high recovery rate, producing a high-purity zinc oxide product. Furthermore, the reduction and recovery process does not require the use of coke or coal, nor does it require acid leaching, resulting in no waste liquid or leaching residue. DETAILED DESCRIPTION

[0019] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0020] As described in the background art, the prior art has the problem of difficulty in reducing and recovering zinc leaching residue with a high recovery rate and producing a high-purity zinc oxide product without introducing a large amount of coke or coal and without involving an acid leaching step. To solve the above technical problems, the first aspect of the present invention provides a method for producing zinc oxide by reducing and recovering zinc leaching residue, comprising: step S1, sintering the zinc leaching residue to form zinc slag particles with a particle size of 1 cm to 3 cm; step S2, mixing biomass and zinc slag particles in a weight ratio of 1: (1 to 3) to obtain a mixed product; step S3, smelting the mixed product to obtain reaction slag and zinc oxide.

[0021] The above method utilizes biomass as a reducing agent, and at the same time finely controls the particle size of the zinc leaching slag during the pretreatment process of sintering and pelletizing, and strictly limits the mixing ratio of biomass and zinc slag particles. It not only effectively recovers the zinc element in the zinc leaching slag, but also optimizes the quality of zinc oxide and produces high-purity zinc oxide. Specifically, by making the zinc leaching slag into particles of a specific particle size, the efficiency and uniformity of the subsequent biomass reduction reaction can be significantly improved, making the recovery of zinc element more thorough. The addition of biomass in a specific weight proportion not only acts as a reducing agent instead of coal and coke to participate in the reaction, but also because the heat generated by its combustion helps to maintain the temperature required for the reaction, reducing additional energy consumption, reducing production costs, and reducing pollution to the environment.

[0022] Specifically, the above-mentioned method provided by the present invention can be implemented using a reduction smelting device. Specifically, it can be a side-blown furnace or an electric furnace. The side-blown furnace is equipped with an injection port for injecting a biomass reducing agent and a combustion-supporting gas (such as air or natural gas), while the electric furnace is equipped with electrodes for heating.

[0023] In summary, the recovery method provided by the present invention not only effectively recovers the zinc element in zinc leaching residue, produces high-purity zinc oxide, and improves the recycling rate of resources, but also opens up a new way for the utilization of biomass, with significant economic and environmental benefits.

[0024] Furthermore, based on the above-mentioned recovery method, in order to achieve a higher recovery rate and obtain a zinc oxide product with fewer impurities and higher purity, the present invention specifically optimizes the composition of the reduction recovery raw material, namely, the zinc leaching residue: the zinc leaching residue includes, by weight, 30-35 parts of zinc, 11-15 parts of iron, 10-15 parts of silicon, 5-7 parts of calcium, 3-5 parts of magnesium, and 0.3-1.0 parts of potassium. The zinc leaching residue includes, but is not limited to, the acid leaching residue produced by acid leaching of zinc sulfide concentrate to obtain zinc calcine.

[0025] In order to significantly increase the contact area of ​​the reduction reaction during the subsequent smelting process, improve the efficiency of the reduction reaction, promote the reduction of zinc and the formation of zinc oxide, and also facilitate the control of the reaction process and the separation of the products, the inventors have optimized the particle size of the zinc slag particles in step S1 to be 1 cm to 1.5 cm after extensive experiments. The sintering and pelletizing temperature is preferably 800°C to 1000°C, which can further improve the structural stability and reactivity of the resulting zinc slag particles. The sintering and pelletizing temperature is more preferably 900±20°C, so as to promote the melting and mixing of the various components in the zinc leaching slag, form a more stable spherical structure, promote the occurrence of the subsequent reduction reaction, and thus more significantly improve the yield and purity of the final zinc oxide product.

[0026] In several typical embodiments, in step S2, biomass and zinc slag particles are mixed in a weight ratio of 1: (1.5-2.0) to obtain a mixed product. Further optimizing the weight ratio of biomass to zinc slag as above can more effectively control the reaction process, avoid energy waste caused by excessive biomass and incomplete zinc recovery caused by insufficient biomass, thereby more efficiently improving the yield and quality of zinc oxide.

[0027] Furthermore, the biomass is selected from one or more of straw, poplar wood chips, pine wood chips, and eucalyptus wood chips. These biomasses are selected based not only on their reducing capacity but also on resource availability and cost-effectiveness. To achieve a better balance between reducing efficiency and suppressing impurity generation, poplar wood chips are more preferably selected, with a carbon content of 30 wt% to 50 wt%.

[0028] Based on this, the inventors, after extensive experiments, have found that prior to mixing, the biomass is preferably ground to a mesh size of 200 to 10 mesh. In the zinc leaching residue recovery method using biomass as a reducing agent provided by the present invention, the biomass is ground to activate its surface before mixing and the reduction reaction begins. The mesh size obtained by grinding is optimized to achieve a more suitable specific surface area for the biomass, more uniform mixing with the zinc slag, and a more uniform structure of mixed particles, thereby improving the reduction effect and the ultimate zinc recovery rate.

[0029] Furthermore, the smelting process in step S3 preferably includes a first smelting and a second smelting performed sequentially, with the first smelting temperature being 400°C to 500°C and the second smelting temperature being 1100°C to 1300°C. This two-stage smelting arrangement promotes the full reduction of zinc and the complete formation of zinc oxide, reducing residual zinc in the final slag and increasing the yield of zinc oxide. Furthermore, the temperature settings during these two smelting stages also help control the temperature and atmosphere during the reaction, improving the quality of the zinc oxide.

[0030] To promote the full progress of the reduction reaction during the smelting process and reduce energy waste caused by excessively long reaction times or incomplete zinc recovery caused by excessively short reaction times, it is further preferred that the time for the first smelting and the second smelting be independently 0.5 to 3.0 hours. Furthermore, it is preferred that the heating rates for the first and second smelting be independently 10°C / min to 30°C / min, thereby improving the stability of the reduction reaction and product uniformity during the smelting process and reducing reaction runaway caused by excessively rapid heating and low reaction efficiency caused by excessively slow heating.

[0031] In several more typical embodiments, the first smelting temperature is preferably 400°C to 450°C, and the time is 1 to 1.5 hours. The first low-temperature smelting is mainly for removing moisture. The preferred temperature is as above, which also helps to preheat and preliminarily reduce the zinc element in the zinc leaching slag, provide good reaction conditions for the subsequent second high-temperature smelting, and improve the purity of the obtained zinc oxide product. During the second high-temperature smelting process, the biomass is carbonized, thereby achieving the reduction of the zinc element in the zinc leaching slag. Preferably, the temperature in this process is 1250°C to 1300°C, and the time is 1 to 2 hours, which can make the temperature range in the smelting environment more suitable for the biomass as a reducing agent, so that it can be more fully carbonized, the reduction of the zinc element is more thorough, and zinc oxide is generated with a higher yield, while also helping to remove impurities in the reaction product.

[0032] Furthermore, the zinc content in the reaction slag is 1 wt% to 4 wt%. The low zinc content in the reaction slag indicates that the recovery method provided by the present invention can recover zinc with higher efficiency, thereby more effectively reducing resource waste and environmental pollution caused by zinc leaching slag.

[0033] A second aspect of the present invention provides zinc oxide, which is prepared by the above-mentioned method of producing zinc oxide by reducing and recovering zinc leaching residue. The zinc oxide prepared by the above-mentioned method not only has high purity, but also has low production cost and small environmental impact, and has significant economic and environmental benefits.

[0034] Furthermore, the zinc content in the zinc oxide is 72 wt% to 78 wt%. In other words, the method provided by the present invention can produce zinc oxide with high purity, making it possible to produce high-purity zinc oxide products using slag solid waste as raw materials, and is suitable for industrial applications with high requirements for zinc oxide quality.

[0035] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0036] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0037] Example 1

[0038] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0039] It should be noted in advance that the component contents of the zinc leaching residue recovered by the present invention are shown in Table 1 below.

[0040] Table 1

[0041] Element Zn Fe Si Ca Mg K content / % 32.37 11.72 11.87 6.566 3.16 0.325

[0042] (1) Sintering the zinc leaching slag at 900°C to form pellets of 1 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0043] (2) Grinding poplar wood chips with a carbon content of 35 wt% to a mesh size of 200, then controlling the mass ratio of zinc slag to poplar wood chips to be 2:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0044] (3) First, the temperature was raised to 450°C at a rate of 25°C / min and reacted for 1 hour, and then the temperature was raised to 1250°C at the same rate and reacted for 2 hours to obtain the post-reaction slag and zinc oxide products.

[0045] Example 2

[0046] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0047] (1) Sintering the zinc leaching slag at 920°C to form pellets with a diameter of 1.5 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0048] (2) Grinding poplar wood chips with a carbon content of 33 wt% to a mesh size of 150, then controlling the mass ratio of zinc slag to poplar wood chips to be 1.5:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0049] (3) First, the temperature was raised to 400°C at a rate of 20°C / min and the reaction was continued for 1.5 h. Then, the temperature was raised to 1300°C at the same rate and the reaction was continued for 1 h to obtain the post-reaction slag and zinc oxide products.

[0050] Example 3

[0051] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0052] (1) Sintering the zinc leaching slag at 800°C to form pellets of 3 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0053] (2) Grinding poplar wood chips with a carbon content of 40 wt% to a mesh size of 100, then controlling the mass ratio of zinc slag to poplar wood chips to be 1:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0054] (3) First, the temperature was raised to 400°C at a rate of 10°C / min and the reaction was continued for 3 h. Then, the temperature was raised to 1300°C at the same rate and the reaction was continued for 0.5 h to obtain the post-reaction slag and zinc oxide products.

[0055] Example 4

[0056] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0057] (1) Sintering the zinc leaching slag at 1000°C to form pellets of 2 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0058] (2) Grinding poplar wood chips with a carbon content of 48 wt% to a mesh size of 50, then controlling the mass ratio of zinc slag to poplar wood chips to be 3:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0059] (3) First, the temperature was raised to 500°C at a rate of 30°C / min and the reaction was continued for 0.5 h. Then, the temperature was raised to 1100°C at the same rate and the reaction was continued for 3 h to obtain the reaction slag and zinc oxide products.

[0060] Example 5

[0061] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0062] (1) Sintering the zinc leaching slag at 700°C to form pellets of 1 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0063] (2) Grinding poplar wood chips with a carbon content of 35 wt% to a mesh size of 200, then controlling the mass ratio of zinc slag to poplar wood chips to be 2:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0064] (3) First, the temperature was raised to 450°C at a rate of 25°C / min and reacted for 1 hour, and then the temperature was raised to 1250°C at the same rate and reacted for 2 hours to obtain the post-reaction slag and zinc oxide products.

[0065] That is, the only difference between this embodiment and embodiment 1 is that the temperature for sintering and pelletizing the zinc leaching slag is changed to 700°C.

[0066] Example 6

[0067] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0068] (1) Sintering the zinc leaching slag at 1200°C to form pellets of 1 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0069] (2) Grinding poplar wood chips with a carbon content of 35 wt% to a mesh size of 200, then controlling the mass ratio of zinc slag to poplar wood chips to be 2:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0070] (3) First, the temperature was raised to 450°C at a rate of 25°C / min and reacted for 1 hour, and then the temperature was raised to 1250°C at the same rate and reacted for 2 hours to obtain the post-reaction slag and zinc oxide products.

[0071] That is, the only difference between this embodiment and embodiment 1 is that the temperature for sintering and pelletizing the zinc leaching slag is changed to 1200°C.

[0072] Example 7

[0073] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0074] (1) Sintering the zinc leaching slag at 900°C to form pellets of 1 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0075] (2) Grinding poplar wood chips with a carbon content of 20 wt% to a mesh size of 200, then controlling the mass ratio of zinc slag to poplar wood chips to be 2:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0076] (3) First, the temperature was raised to 450°C at a rate of 25°C / min and reacted for 1 hour, and then the temperature was raised to 1250°C at the same rate and reacted for 2 hours to obtain the post-reaction slag and zinc oxide products.

[0077] That is, the only difference between this embodiment and embodiment 1 is that poplar wood chips with a carbon content of 20 wt% are selected as the biomass reducing agent.

[0078] Example 8

[0079] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0080] (1) Sintering the zinc leaching slag at 900°C to form pellets of 1 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0081] (2) Grinding poplar wood chips with a carbon content of 55 wt% to a mesh size of 200, then controlling the mass ratio of zinc slag to poplar wood chips to be 2:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0082] (3) First, the temperature was raised to 450°C at a rate of 25°C / min and reacted for 1 hour, and then the temperature was raised to 1250°C at the same rate and reacted for 2 hours to obtain the post-reaction slag and zinc oxide products.

[0083] That is, the only difference between this embodiment and embodiment 1 is that poplar wood chips with a carbon content of 55 wt% are selected as the biomass reducing agent.

[0084] Example 9

[0085] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0086] (1) Sintering the zinc leaching slag at 900°C to form pellets of 1 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0087] (2) Grinding poplar wood chips with a carbon content of 35 wt% to a mesh size of 300, then controlling the mass ratio of zinc slag to poplar wood chips to be 2:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0088] (3) First, the temperature was raised to 450°C at a rate of 25°C / min and reacted for 1 hour, and then the temperature was raised to 1250°C at the same rate and reacted for 2 hours to obtain the post-reaction slag and zinc oxide products.

[0089] That is, the only difference between this embodiment and embodiment 1 is that the mesh size of the biomass before mixing is changed to 300 meshes.

[0090] Example 10

[0091] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0092] (1) Sintering the zinc leaching slag at 900°C to form pellets of 1 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0093] (2) Poplar wood chips with a carbon content of 35 wt% were used as biomass, and the mass ratio of zinc slag to poplar wood chips was controlled to be 2:1. The ground poplar wood chips were sprayed into a side-blown furnace to mix the two to obtain a mixed product;

[0094] (3) First, the temperature was raised to 450°C at a rate of 25°C / min and reacted for 1 hour, and then the temperature was raised to 1250°C at the same rate and reacted for 2 hours to obtain the post-reaction slag and zinc oxide products.

[0095] That is, the only difference between this embodiment and embodiment 1 is that the biomass is not ground before mixing, and the particle size is about 2 cm.

[0096] Example 11

[0097] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0098] (1) Sintering the zinc leaching slag at 900°C to form pellets of 1 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0099] (2) Grinding poplar wood chips with a carbon content of 35 wt% to a mesh size of 200, then controlling the mass ratio of zinc slag to poplar wood chips to be 2:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0100] (3) The temperature was raised to 1200°C at a rate of 15°C / min and the reaction was continued for 1 hour to obtain the reaction slag and zinc oxide products.

[0101] That is, the only difference between this embodiment and embodiment 1 is that the smelting process includes only one smelting.

[0102] Example 12

[0103] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0104] (1) Sintering the zinc leaching slag at 900°C to form pellets of 1 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0105] (2) Grinding poplar wood chips with a carbon content of 35 wt% to a mesh size of 200, then controlling the mass ratio of zinc slag to poplar wood chips to be 2:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0106] (3) First, the temperature was raised to 300°C at a rate of 5°C / min and the reaction was continued for 4 h. Then, the temperature was raised to 1500°C at a rate of 40°C / min and the reaction was continued for 0.2 h to obtain the reaction slag and zinc oxide products.

[0107] That is, the only difference between this embodiment and embodiment 1 is that the conditions used in the two-stage smelting treatment are different.

[0108] Comparative Example 1

[0109] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0110] (1) Sintering the zinc leaching slag at 900°C to form pellets of 0.5 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0111] (2) Grinding poplar wood chips with a carbon content of 35 wt% to a mesh size of 200, then controlling the mass ratio of zinc slag to poplar wood chips to be 2:1, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0112] (3) First, the temperature was raised to 450°C at a rate of 25°C / min and reacted for 1 hour, and then the temperature was raised to 1250°C at the same rate and reacted for 2 hours to obtain the post-reaction slag and zinc oxide products.

[0113] That is, the only difference between this comparative example and Example 1 is that the particle size of the zinc slag particles and the amount of biomass added are different.

[0114] Comparative Example 2

[0115] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0116] (1) Sintering the zinc leaching slag at 900°C to form pellets of 4.0 cm to obtain zinc slag particles, which are then sent to a reduction smelting device;

[0117] (2) Grinding poplar wood chips with a carbon content of 35 wt% to a mesh size of 200, then controlling the mass ratio of zinc slag to poplar wood chips to be 1:4, spraying the ground poplar wood chips into a side-blown furnace, and mixing the two to obtain a mixed product;

[0118] (3) First, the temperature was raised to 450°C at a rate of 25°C / min and reacted for 1 hour, and then the temperature was raised to 1250°C at the same rate and reacted for 2 hours to obtain the post-reaction slag and zinc oxide products.

[0119] That is, the only difference between this comparative example and Example 1 is that the particle size of the zinc slag particles and the amount of biomass added are different.

[0120] Comparative Example 3

[0121] A method for producing zinc oxide by reducing and recovering zinc leaching residue:

[0122] (1) The zinc leaching residue was mixed with poplar wood chips with a carbon content of 35 wt% and sintered at 900°C to form pellets to a particle size of 2 cm to obtain mixed zinc slag particles, which were then sent to a reduction smelting device;

[0123] (2) First, the temperature was raised to 450°C at a rate of 25°C / min and reacted for 1 hour, and then the temperature was raised to 1250°C at the same rate and reacted for 2 hours to obtain the post-reaction slag and zinc oxide products.

[0124] That is, the only difference between this comparative example and Example 1 is that the zinc leaching residue is sintered together with the unground biomass to form pellets.

[0125] The zinc recovery rates of the embodiments and comparative examples are shown in Table 2, as are the zinc contents in the resulting slag and zinc oxide product after the reaction.

[0126] Table 2

[0127]

[0128]

[0129] As can be seen from the above description, the embodiments of the present invention achieve reduction smelting of zinc leaching residue using biomass as a reducing agent without the introduction of coke or coal and without acid leaching, and recover a zinc oxide product with a high recovery rate. The resulting zinc oxide product has a high zinc content and high purity.

[0130] In particular, in the above embodiments, it can be seen from Examples 5 and 6 that, regarding the sintering ball making process, when the sintering temperature of the zinc leaching slag is too high, over-sintering may occur, resulting in a decrease in porosity and an increase in density, while if the sintering temperature is too low, the zinc leaching slag will not be fully sintered, which is not conducive to increasing the reaction rate.

[0131] Regarding the grinding process of the biomass reducing agent, when grinding to a smaller particle size, parasitic side reactions are likely to intensify, which can significantly reduce the selectivity and efficiency of the reaction, such as in Example 13. Overly large particles can lead to more pronounced internal diffusion limitations, slowing the diffusion of reactants within the particles and affecting the reaction rate.

[0132] It should be noted that the terms "first," "second," and the like in the specification and claims of this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the application described herein can, for example, be implemented in an order other than that described herein.

[0133] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for producing zinc oxide by reducing and recovering zinc leaching residue, characterized in that: include: Step S1, sintering and pelletizing the zinc leaching slag to obtain zinc slag particles with a particle size of 1 cm to 3 cm; Step S2, mixing the biomass and the zinc slag particles in a weight ratio of 1: (1-3) to obtain a mixed product; Step S3, smelting the mixed product to obtain reaction slag and the zinc oxide.

2. The method for producing zinc oxide by reducing and recovering zinc leaching residue according to claim 1, characterized in that: The zinc leaching slag comprises, by weight, 30 to 35 parts of zinc, 11 to 15 parts of iron, 10 to 15 parts of silicon, 5 to 7 parts of calcium, 3 to 5 parts of magnesium and 0.3 to 1.0 parts of potassium.

3. The method for producing zinc oxide by reducing and recovering zinc leaching residue according to claim 1 or 2, characterized in that: In step S1, the particle size of the zinc slag particles is 1 cm to 1.5 cm; Preferably, the sintering temperature is 800°C to 1000°C.

4. The method for producing zinc oxide by reducing and recovering zinc leaching residue according to any one of claims 1 to 3, characterized in that: In step S2, the biomass and the zinc slag particles are mixed in a weight ratio of 1: (1.5-2.0) to obtain the mixed product.

5. The method for producing zinc oxide by reducing and recovering zinc leaching residue according to any one of claims 1 to 4, characterized in that: The biomass is selected from one or more of straw, poplar wood chips, pine wood chips and eucalyptus wood chips, preferably poplar wood chips, and the carbon content of the poplar wood chips is 30wt% to 50wt%.

6. The method for producing zinc oxide by reducing and recovering zinc leaching residue according to any one of claims 1 to 5, characterized in that: In step S3, the smelting process includes a first smelting and a second smelting performed sequentially, and: The temperature of the first smelting is 400° C. to 500° C.; The second smelting temperature is 1100°C to 1300°C.

7. The method for producing zinc oxide by reducing and recovering zinc leaching residue according to claim 6, characterized in that: The time of the first smelting and the second smelting are each independently 0.5 h to 3.0 h, and the heating rates are each independently 10° C. / min to 30° C. / min.

8. The method for producing zinc oxide by reducing and recovering zinc leaching residue according to any one of claims 1 to 7, characterized in that: The zinc content in the slag after the reaction is 1wt% to 4wt%.

9. A zinc oxide, characterized in that The zinc oxide is prepared by the method for producing zinc oxide by reducing and recovering zinc leaching residue according to any one of claims 1 to 8.

10. The zinc oxide according to claim 9, characterized in that The zinc content in the zinc oxide is 72wt% to 78wt%.

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