Novel process for separating tin and lead from low-grade tin-lead-zinc smoke dust produced by fuming furnace

Abstract

The invention discloses a novel process for separating tin and lead from low-grade tin-lead-zinc smoke dust produced by a fuming furnace. Low-grade tin-lead-zinc smoke dust produced by treating a low-tin material through a fuming furnace vulcanization volatilization method is used as a raw material, and the method comprises the processes of impurity removal and dezincification, desulfurization by adding a desulfurizing agent, desulfurization and dearsenification by roasting, reduction and precipitation of crude lead, strong reduction smelting treatment in an electric furnace and the like. The invention provides a novel smelting process aiming at a low-grade tin high-lead zinc smoke dust raw material produced by a low-tin material treated by a fuming furnace vulcanization volatilization method, so that the energy consumption cost is greatly reduced, the lead is thoroughly removed, the lead and tin separation effect is good, the technical and economic indexes are further improved, and the smelting efficiency and the economic benefits are improved.

Description

Technical Field:

[0001] The present invention belongs to the technical field of the combined wet and pyrometallurgical process for non-ferrous metal smelting, and relates to the recovery of rare metals from fuming furnace metal smelting in the aspect of resource recycling, and particularly relates to a new process for separating tin and lead from low-grade tin-lead-zinc dust produced by a fuming furnace. Background Art:

[0002] The fuming metallurgy technology is widely used to treat various slag, mud, dust and other materials containing zinc, lead, and tin after pyrometallurgy and hydrometallurgy. For the treatment of low-tin materials by the fuming furnace sulfide volatilization method, the produced low-grade tin-lead-zinc dust still contains various precious metal elements mentioned above from the materials after fuming furnace smelting. How to recycle the above solid waste materials is a realistic issue in the current fuming smelting field.

[0003] For example, in Chinese Patent CN102352443A, "Method for Producing Zinc Sulfate Heptahydrate, Crude Tin and Crude Lead from Tin Smelting Dust": The raw material tin smelting dust is characterized by containing 12 - 35% zinc, 2 - 12% lead, 20 - 30% tin, within 2% sulfur, within 1.5% iron, and about 2% arsenic. In view of the composition characteristics of the tin smelting dust, a new combined wet and pyrometallurgical process of leaching zinc with dilute sulfuric acid - preparing zinc sulfate heptahydrate from zinc solution - electric furnace smelting of tin-rich slag - vacuum distillation to produce crude tin and crude lead is developed.

[0004] Another example is Chinese Patent CN112609084A, "Comprehensive Treatment Method for High-Zinc-Lead-Tin Dust from Fuming Furnace": The raw material high-zinc-lead-tin dust from the fuming furnace is characterized by containing 20 - 30% zinc, 10 - 15% lead, and 25 - 30% tin. Its treatment process includes the following steps: (1) oxygen pressure leaching of zinc; (2) neutralization to remove iron; (3) removing copper and cadmium with zinc powder; (4) purifying to remove nickel and cobalt; (5) formulating and granulating the leaching residue for sintering; (6) reducing and smelting the sintered residue into a lead-tin alloy; (7) vacuum distillation of the lead-tin alloy. The process of the present invention effectively overcomes the current situation that the direct acid leaching of zinc from the existing fuming furnace dust has a low leaching rate and it is difficult to completely separate zinc, lead, and tin, and realizes the clean zinc extraction from the high-zinc-lead-tin dust of the fuming furnace, achieving the purposes of energy conservation, emission reduction, consumption reduction, and value addition.

[0005] There is also, such as Chinese Patent Publication No. CN 106086413 B, the disclosed "Process for Recycling Resources from Wet Zinc Smelting Lead-Silver Slag". A process for recycling resources from wet zinc smelting lead-silver slag disclosed therein includes batching the dried lead-silver slag, lead concentrate and additives to obtain a mixture; granulating the mixture and then feeding it into an oxygen bottom-blown furnace for oxidative smelting to separate primary lead and slag; the slag enters an oxygen side-blown metal smelting reduction furnace, adding crushed coal and flux into the oxygen side-blown metal smelting reduction furnace to form the slag of the oxygen side-blown metal smelting reduction furnace; the slag enters a fuming furnace to obtain secondary lead; for the silver entering the primary lead and secondary lead, it enters the anode slime during the lead electrolytic refining process of the primary lead and secondary lead, and silver is extracted from the anode slime; for the zinc and lead in the fuming furnace dust, the dust is subjected to defluorination and dechlorination, zinc is leached by wet method, zinc is electrowon, and lead enters the leaching residue and is recycled through lead smelting. The process of the present invention is simple, the recovery rate of lead in the lead-silver slag is about 95%, the recovery rate of zinc is about 90%, the recovery rate of silver is about 95%, and the sulfur utilization rate is about 90%.

[0006] There is also, such as Application Publication No. CN 102352443 A, "Method for Producing Zinc Sulfate Heptahydrate, Crude Tin and Crude Lead from Tin Smelting Fume". The present invention discloses a method for producing zinc sulfate heptahydrate, crude tin and crude lead from tin smelting fume, including the following steps: (1) raw material pretreatment; (2) leaching and separating zinc with dilute sulfuric acid solution; (3) purifying the crude zinc sulfate solution and preparing zinc sulfate heptahydrate; (4) electric furnace smelting of the tin-rich slag to produce a tin-lead alloy; (5) refining the tin-lead alloy by conventional liquation method (temperature 500°C - 600°C) and segregation method (temperature 230°C - 240°C) to increase the Sn+Pb grade in the alloy to 94% - 96%. Return the refining slag to the electric furnace smelting batching for treatment; (6) high-temperature vacuum distillation to produce crude tin and crude lead. The present invention can effectively utilize tin smelting fume, save resources, and comprehensively recover metals such as tin, lead, zinc, and copper.

[0007] It can be seen from the above-disclosed prior art solutions that in the various solutions disclosed therein, the contents and varieties of various rare metal elements contained in the tin-lead-zinc dust raw materials produced by the fuming furnace used are quite different, so the metal element components to be recycled disclosed therein are also different. None of them are process methods for extracting from the tin-lead-zinc dust raw materials produced by a fuming furnace with high lead and low tin content, such as the raw material characteristics include: zinc 10 - 30%, lead 10 - 25%, tin 5 - 15%, sulfur about 10%, iron about 1.5%, arsenic about 2%. For example, for the tin-lead-zinc dust raw materials produced by some fuming furnaces, their sulfur content is high while the tin grade is low; that is, high lead and low tin. How to extract and separate tin and lead metals is not involved.

[0008] How to provide a new process for separating tin and lead from low-grade tin-lead-zinc dust produced by a fuming furnace. The main differences in the raw material characteristics of the above-mentioned existing technologies are as follows: the tin grade is relatively low, that is, the raw material with high lead and low tin. Therefore, for the low-grade tin-lead-zinc dust raw material produced by the fuming furnace sulfide volatilization method for treating low-tin materials, that is, the raw material with a high lead content and a low tin content in the raw material composition, how to develop a new smelting process to make the production of low-grade tin-lead-zinc dust raw material smooth, improve technical and economic indicators, improve smelting efficiency and economic benefits, save production costs, and meet the requirements of environmental protection and circular economy. Summary of the Invention:

[0009] The present invention provides a new process for separating tin and lead from low-grade tin-lead-zinc dust produced by a fuming furnace; using the low-grade tin-lead-zinc dust produced by the fuming furnace sulfide volatilization method for treating low-tin materials as raw materials, including processes such as impurity removal and zinc removal, adding a desulfurizing agent for desulfurization, roasting for desulfurization and arsenic removal, reducing and melting out crude lead, and electric furnace strong reduction smelting treatment, etc. For the low-grade tin-high lead-zinc dust raw material produced by the fuming furnace sulfide volatilization method for treating low-tin materials, a new smelting process is provided to make the production run smoothly, while greatly reducing the energy consumption cost, removing lead cleanly and thoroughly, having good separation effect of lead and tin, and further improving technical and economic indicators, improving smelting efficiency and economic benefits.

[0010] The purpose of the present invention is to provide a new process for separating tin and lead from low-grade tin-lead-zinc dust produced by a fuming furnace, using the low-tin high-lead dust produced by the fuming furnace sulfide volatilization method for treating low-tin materials as raw materials, including the following method steps:

[0011] 1) Impurity removal and zinc removal: Mechanically remove impurities such as iron blocks, slag, cloth strips, and stones entrained in the low-tin high-lead dust raw material, and then perform zinc removal treatment by using a dilute sulfuric acid solution stirring leaching-washing process to obtain impurity-removed and zinc-removed slag;

[0012] 2) Adding a desulfurizing agent for desulfurization: Add a desulfurizing agent to the impurity-removed and zinc-removed slag in step 1); carry out a desulfurization reaction, which is mainly aimed at the sulfur in lead sulfate in the lead-tin slag, and convert lead sulfate into lead carbonate or lead hydroxide. Control the residual rate of the desulfurizing agent in the liquid of the desulfurized material after the desulfurization solution reaction to be 1-3 g / L. After the desulfurization reaction is completed, filter press to obtain washed water soot;

[0013] 3) Roasting for desulfurization and arsenic removal: Dry and desulfurize, remove arsenic, and remove antimony from the washed water soot in step 2) to produce tin-lead calcine, and control the sulfur and arsenic contents in the tin-lead calcine to be below 0.3-0.5 Wt%, while increasing the tin and lead grades;

[0014] 4), Reduction and fusing to produce crude lead: The stanniferous lead calcine from step 3) is subjected to fusing treatment in a reverberatory furnace. By controlling the weak reduction atmosphere, temperature, and slag type, the lead oxides in the stanniferous lead calcine are preferentially reduced. The fusing treatment produces stanniferous lead slag, crude lead, and dust materials. The crude lead is sent to the lead refining workshop to produce refined lead, the dust materials are returned to the batching process, and the stanniferous lead slag is used as the raw material for the next step of high-temperature strong reduction smelting of tin in an electric furnace;

[0015] 5), Electric furnace strong reduction smelting treatment: The stanniferous lead slag produced by the reduction and fusing treatment of the reverberatory furnace in step 4) is subjected to electric furnace strong reduction smelting treatment. The rich slag produced is sent to the fuming furnace, and the stanniferous lead alloy produced is sent to the tin refining workshop for impurity removal and then vacuum separated to extract tin and lead products. The produced dust is collected in sections. The high-tin dust is returned to the batching process, and the low-tin dust is sent to the fuming furnace.

[0016] For the new process for separating tin and lead from low-grade stanniferous lead-zinc dust produced by a fuming furnace, in step 1), the low-grade stanniferous lead-zinc dust raw material contains: lead 18 - 30.2 Wt%, tin 8 - 12.5 Wt%; and the zinc content in the dezincified slag is controlled to be 1.0 - 2.5 Wt%.

[0017] For the new process for separating tin and lead from low-grade stanniferous lead-zinc dust produced by a fuming furnace, in step 2), the desulfurizing agent is a mixed alkaline solution of sodium carbonate and / or sodium hydroxide.

[0018] For the new process for separating tin and lead from low-grade stanniferous lead-zinc dust produced by a fuming furnace, in step 2), the conditions for the desulfurization reaction are: controlling the reaction time of the desulfurization solution to be 55 - 70 min, the reaction temperature to be 65 - 75 °C, the liquid-solid ratio during the reaction of the desulfurization solution to be 10:1 - 1.2; at the same time, controlling the mass molar ratio of sodium to lead during the reaction of the desulfurization solution to be 1.1 - 1.2:1, and after the reaction conversion of the desulfurization solution, controlling the residual rate of the desulfurizing agent in the feed liquid to be 1 - 3 g / L.

[0019] For the new process for separating tin and lead from low-grade stanniferous lead-zinc dust produced by a fuming furnace, in step 3), the washing water soot is dried and desulfurized, dearsenified, and deantimonized to obtain stanniferous lead calcine, and the sulfur and arsenic contents in the stanniferous lead calcine are controlled to be less than 0.3 - 0.5 Wt% respectively; controlling its process technical operation conditions: adding reducing coal to the raw material, the roasting temperature is 820 - 980 °C; controlling the oxidation / reduction roasting atmosphere during the roasting process to be a negative pressure of -12 - -16 Pa at the kiln tail.

[0020] For the new process for separating tin and lead from low-grade stanniferous lead-zinc dust produced by a fuming furnace, in step 4), the process technical operation conditions for the fusing treatment are: controlling the furnace temperature during the reaction of the reverberatory furnace to be 920 - 1050 °C; at the same time, adding 5 - 10% of anthracite or sulfur as a reducing agent and 0 - 5% of soda ash as a fusing agent based on the mass of the raw materials in the reverberatory furnace mixture.

[0021] For the new process of separating tin and lead from low-grade tin-lead-zinc dust produced by a fuming furnace, in step 5), the operating conditions of the electric furnace strong reduction smelting treatment process are as follows: control the smelting treatment temperature of the electric furnace strong reduction raw materials at 1220 - 1280 °C; according to the content of the materials added to the electric furnace, add reducing agents anthracite or coke, and control the negative pressure inside the electric furnace cavity at -65 - -150 Pa.

[0022] Preferably, the amount of reducing agents anthracite and coke added is such that in the tin-lead slag added to the electric furnace, when the iron content in the tin-lead slag is below 3%, the amount of reducing agents anthracite and coke added is 2 - 4% more than the theoretical amount; when the iron content is 7% or above, the amount of reducing agents anthracite and coke added is 5% more than the theoretical amount; at the same time, control the negative pressure inside the electric furnace cavity at -70 - -120 Pa.

[0023] The new process for separating tin and lead from low-grade tin-lead-zinc dust produced by a fuming furnace disclosed in the present invention uses the dust containing low tin, high lead and zinc produced by treating low-tin materials by the fuming furnace sulfide volatilization method as the raw material, and aims at the low-grade tin-lead-zinc dust raw material produced by treating low-tin materials by the fuming furnace sulfide volatilization method to extract tin and lead products. The new process has the following beneficial effects:

[0024] First, the present invention can greatly reduce the energy consumption in the production process. In the existing production process, the cooling process for removing lead has high energy consumption. First, brine at 90 °C or above is placed in a heat exchanger for heat exchange treatment to reduce its temperature to below 5 °C. Under the above temperature conditions, when lead chloride, i.e., lead, precipitates, and when the lead content is low, Pb content ≤ 3 g / L, it is filtered while it is cold. The slag is a by-product of lead chloride, and the filtrate is the sodium chloride brine after lead removal. After heat exchange through the heat exchanger, calcium chloride is first added to remove sulfate ions completely, and then sodium chloride is added to make the brine reach Cl ≥ 180 g / L, and then it is re-injected into the lead leaching process. That is, the brine has to be heated to above 90 °C again, which causes a large amount of waste of energy, i.e., it is not energy-saving; moreover, it is easy to cause blockage of equipment and pipelines due to crystal precipitation in the filter.

[0025] Second, the lead removal is not thorough, resulting in the subsequent lead leaching efficiency not reaching the expected effect. The Pb content remaining in the tin slag is as high as over 3.1%, and the effect of separating lead and tin is not ideal. While the Pb content in the tin slag in the present invention is only about 2.1%.

[0026] Third, the tin recovery rate is higher. In the new process of the present invention, the tin recovery rate reaches over 96.5% and can be directly sold as a product; the filtrate is a mixed solution of lead chloride and sodium chloride, and the filtrate enters the lead removal process; while the existing technical process methods cannot meet the above technical effect requirements.

[0027] Fourthly, the raw materials targeted by the present invention mainly refer to the new process method for separating tin and lead from the low-tin high-lead and zinc-containing dust produced by treating low-tin materials by the fuming furnace sulfide volatilization method with high lead and low tin and low tin grade. The recovery rate of tin reaches over 96.5%; achieving double benefits of economy and environmental protection. Specific implementation mode:

[0028] The following further describes the present invention in conjunction with specific implementation modes. The present invention is not limited to the embodiments, and each component of the present invention can be obtained commercially.

[0029] A new process for separating tin and lead from low-grade tin-lead-zinc dust produced by a fuming furnace, using the low-tin high-lead dust produced by treating low-tin materials by the fuming furnace sulfide volatilization method as the raw material, includes the following method steps:

[0030] 1) Impurity removal and zinc removal: Remove impurities such as iron blocks, slag, cloth strips, and stones entrained in the low-tin high-lead dust raw material by mechanical means, and then perform zinc removal treatment by the stirring leaching - washing process with dilute sulfuric acid solution to obtain the impurity-removed and zinc-removed slag; the low-grade tin-lead-zinc dust raw material contains: lead 18 - 30.5Wt%, tin 8 - 12.5Wt%; control the zinc content in the zinc-removed slag to be 1.0 - 2.5Wt%.

[0031] 2) Adding a desulfurizing agent for desulfurization: Add a desulfurizing agent, which is a mixed alkaline solution of sodium carbonate and / or sodium hydroxide, to the impurity-removed and zinc-removed slag in step 1); perform a desulfurization reaction, which mainly targets the sulfur in lead sulfate in the lead-tin slag, and convert lead sulfate into lead carbonate or lead hydroxide. Control the residual rate of the desulfurizing agent in the liquid of the desulfurized material after the desulfurization solution reaction to be 1 - 3g / L. After the desulfurization reaction is completed, filter press to obtain washed ash.

[0032] The conditions for the desulfurization reaction are: control the reaction time of the desulfurization solution to be 55 - 70min, the reaction temperature to be 60 - 70°C, control the liquid-solid ratio during the desulfurization solution reaction to be 10:1 - 1.2; at the same time, control the mass molar ratio of sodium to lead during the desulfurization solution reaction to be 1.1 - 1.2:1, and the desulfurization rate after the desulfurization solution reaction is converted to be 95 - 97%; the desulfurizing agent is sodium carbonate or a mixture of sodium carbonate.

[0033] 3) Roasting for desulfurization and dearsenication: Dry the washed ash in step 2) and perform desulfurization, dearsenication, and deantimony to produce tin-lead calcine, control the sulfur and arsenic content in the tin-lead calcine to be below 0.3 - 0.5Wt% respectively, and at the same time increase the tin and lead grades; the specific operation is to dry the washed ash and perform desulfurization, dearsenication, and deantimony to obtain tin-lead calcine, control the sulfur and arsenic content in the tin-lead calcine to be lower than 0.3 - 0.5Wt% respectively; at the same time, add the corresponding coal as a reducing agent, and control its process technical operation conditions: the roasting temperature is 820 - 980°C; control the oxidation / reduction roasting atmosphere during the roasting process to be the kiln tail negative pressure of -12 - -16Pa.

[0034] 4) Reduction and liquation to produce crude lead: The tin-bearing lead calcine from step 3) is subjected to liquation treatment in a reverberatory furnace. By controlling the weak reduction atmosphere, temperature, and slag type, the lead oxides in the tin-bearing lead calcine are preferentially reduced. The liquation treatment produces tin-lead slag, crude lead, and flue dust materials. The crude lead is sent to the lead refining workshop to produce refined lead, the flue dust materials are returned to the batching process, and the tin-lead slag is used as the raw material for the next step of high-temperature strong reduction smelting of tin in an electric furnace. The process technical operation conditions for the liquation treatment are as follows: control the furnace temperature during the reverberatory furnace reaction at 920 - 1050 °C; simultaneously add 5 - 10% of anthracite or the corresponding amount of sulfur as a reducing agent and 0 - 5% of soda ash as a liquation agent based on the mass of the raw materials in the reverberatory furnace mixture.

[0035] 5) Electric furnace strong reduction smelting treatment: The tin-lead slag produced by the reduction and liquation treatment of the reverberatory furnace in step 4) is subjected to electric furnace strong reduction smelting treatment. The rich slag produced is sent to the fuming furnace, and the tin-lead alloy produced is sent to the tin refining workshop for impurity removal and then vacuum separated to extract tin and lead products. The flue dust produced is collected in sections. The high-tin flue dust is returned to the batching process, and the low-tin flue dust is sent to the fuming furnace. The process technical operation conditions for the electric furnace strong reduction smelting treatment are to control the temperature of the electric furnace strong reduction raw material smelting treatment at 1220 - 1280 °C; according to the content of the materials added to the electric furnace, add anthracite and coke as reducing agents, and control the negative pressure inside the electric furnace cavity at -65 - -150 Pa.

[0036] Preferably, in the new process for separating tin and lead from low-grade tin-lead-zinc flue dust produced by a fuming furnace of the present invention, the amounts of anthracite and coke added as reducing agents are as follows: when the iron content in the tin-lead slag added to the electric furnace is below 3%, the amount of anthracite and coke added as reducing agents exceeds the theoretical amount by 2 - 4%; when the iron content is 7% or above, the amount of anthracite and coke added as reducing agents exceeds the theoretical amount by 5%. At the same time, control the negative pressure inside the electric furnace at -70 - -120 Pa.

[0037] In the following examples, the parts not described are implemented according to the above specific implementation manners.

[0038] Example 1

[0039] The raw materials and components of this example can be obtained commercially.

[0040] The new process for separating tin and lead from low-grade tin-lead-zinc flue dust produced by a fuming furnace disclosed in the present invention uses the low-tin high-lead flue dust produced by the fuming furnace sulfuration volatilization method to treat low-tin materials as the raw material, with a dry weight of 3 (t) in total. The main chemical components of the low-grade tin-high-lead-zinc flue dust produced by the fuming furnace in the raw material are as follows in mass percentage (%): Sn 8.2, Pb 21.7, Zn 16.1, S 10.3, Fe 1.5, As 1.8;

[0041] 1) Impurity removal and dezincing: The raw materials are removed from mechanical entrained iron blocks, slag, cloth strips, stones and other impurities, and dezincified by a stirring leaching - washing process with dilute sulfuric acid solution; the impurity - removed and dezincified slag is obtained, and the zinc content in the impurity - removed and dezincified slag is controlled at 2.3%.

[0042] 2) Desulfurization by adding desulfurizing agent: The dezincified slag is added to the desulfurizing agent soda solution for conversion desulfurization treatment, that is, the desulfurization reaction is carried out. The desulfurization reaction time is controlled at 60 min, the reaction temperature is 65 °C, and the mass molar ratio of sodium to lead in the desulfurization solution during the reaction, that is, the reaction molar ratio (by sodium carbonate: lead sulfate) is 1.1:1, and the reaction liquid - solid ratio is 10:1; the desulfurization rate after conversion is about 96%, and the residual sodium carbonate in the feed liquid is controlled at about 2 g / L; after the dezincified slag is subjected to conversion desulfurization, it is filtered to obtain washed - water soot.

[0043] 3) Roasting for desulfurization and dearsenification: The washed - water soot in step 2) is subjected to roasting for desulfurization and dearsenification. The main chemical composition of this washed - water soot in mass percentage (%) is: H2O 31.7, Sn 14.7, Pb 38.4, Zn 3.1, S 4.2; the main process technical operation conditions are mainly a roasting temperature of 850 - 950 °C; 1 - 1.5% of the raw material amount of reducing coal is added, and the oxidation / reduction roasting atmosphere is controlled; the negative pressure at the tail of the electric furnace kiln is - 12 - - 15 Pa; the roasted product contains tin - lead calcine, in which the sulfur content is 0.455 Wt% and the arsenic content is 0.385 Wt%.

[0044] 4) Reduction melting to produce crude lead: Using an electric furnace, the tin - lead calcine produced by roasting in step 3) is used as the raw material, about 8% of anthracite is added as the reducing agent, and about 3% of soda ash is added as the flux. The mixed materials are mixed evenly and put into the furnace, and the furnace temperature is 900 - 1000 °C; after reduction melting in a reverberatory furnace, crude lead, tin - lead slag, dust materials, etc. are produced. The crude lead can be sent to the lead refining workshop to produce refined lead, the tin - lead slag is used as the raw material for the next step of high - temperature strong reduction smelting of tin in an electric furnace, and the dust is returned to the batching. The crude lead produced contains 92.18% lead and 2.29% tin; while the tin - lead slag contains 7.07% lead, 34.62% tin, and 2.8% iron. 92% of the Pb element enters the crude lead and 5.5% enters the tin - lead slag; 7.5% of the Sn element enters the crude lead and 88.7% enters the tin - lead slag.

[0045] 5) Electric furnace reduction smelting treatment: The tin-lead slag produced after the reduction and liquation in the reverberatory furnace in step 4) is mixed with anthracite, the reducing agent, in an amount 1.03 times the theoretical requirement, and several fluxes such as limestone and quartzite are added according to the slag-forming requirements. The mixed material is evenly fed into the furnace. The furnace temperature is 1250 - 1280 °C, and the negative pressure in the furnace is -80 - -120 Pa. After high-temperature and strong reduction smelting in the electric furnace, the rich slag is sent to the fuming furnace, and the tin-lead alloy is sent to the tin refining workshop for impurity removal and then vacuum separated to extract tin and lead. The flue dust is collected in sections. The high-tin flue dust is returned to the batching, and the low-tin flue dust is sent to the fuming furnace. The dry basis analysis (%) of the produced tin-lead alloy shows 14.28% lead and 82.66% tin; the rich slag contains 1.63% lead and 3.46% tin, that is, the lead content in the tin slag is lower. 71.3% of the Pb element enters the tin-lead alloy, and 8.2% enters the rich slag; 84.3% of the tin element enters the tin-lead alloy, and 4.9% enters the rich slag. After calculation, the tin recovery rate is 96.6%.

[0046] Example 2,

[0047] A new process for separating tin and lead from low-grade tin-lead-zinc flue dust produced by a fuming furnace disclosed in the present invention uses the low-tin and high-lead flue dust produced by the sulfide volatilization method of the fuming furnace to treat low-tin materials as raw materials, with a dry weight of 3 (t) in total. The main chemical components of the raw material, low-grade tin-high-lead-zinc flue dust produced by the fuming furnace, take 3 t of raw material soot (dry basis), and the main components are: zinc 14.82%, lead 18.44%, Zn 15.4%, tin 8.83%, S 9.6, Fe 1.43, As 1.67; The production is carried out according to the following process method: 1) Impurity removal and zinc removal: The raw materials are removed from mechanical entrained iron blocks, slag, cloth strips, stones and other impurities, and zinc is removed by the stirring leaching - washing process with dilute sulfuric acid solution; the impurity-removed and zinc-removed slag is obtained, and the zinc content in the impurity-removed and zinc-removed slag is controlled at 2.3%.

[0048] 2) Adding a desulfurizing agent for desulfurization, adding a mixed alkali solution of soda ash and sodium hydroxide as the desulfurizing agent to the zinc-removed slag for conversion desulfurization treatment, that is, carrying out a desulfurization solution reaction. The reaction time of the desulfurization solution is controlled at 60 min, the reaction temperature is 70 °C, and the mass molar ratio of sodium to lead in the desulfurization solution reaction is controlled, that is, the reaction molar ratio (by sodium carbonate: lead sulfate) is 1.1:1, and the reaction liquid-solid ratio is 10:1.1; the desulfurization rate after conversion is about 97%, and the residual rate of sodium carbonate in the feed liquid is controlled at about 3 g / L; the zinc-removed slag is filtered under pressure after conversion desulfurization to obtain washed soot, and the washed soot is obtained by pressure filtration.

[0049] 3) Roasting for desulfurization and dearsenification: The washed water soot in step 2) is subjected to roasting for desulfurization and dearsenification. The main chemical composition of this washed water soot in mass percentage (%) is: H2O 32.7, Sn 15.2, Pb 32.3, Zn 2.3, S 3.9. The main process technical operation conditions are mainly roasting temperature of 850 - 950 °C; adding 1 - 1.5% of reduction coal based on the raw material amount, controlling the oxidation / reduction roasting atmosphere; the negative pressure at the kiln tail is -12 - -15 Pa; the roasted product is tin-lead calcine, which contains 0.42% sulfur and 0.35% arsenic;

[0050] 4) Reduction melting to produce crude lead: Using an electric furnace, the tin-lead calcine produced by roasting in step 3) is used as the raw material, adding about 8% of anthracite or the corresponding amount of sulfur as the reducing agent, and about 3% of soda ash as the flux. The mixed materials are evenly mixed and fed into the furnace, and the furnace temperature is 900 - 1000 °C. After reduction melting in a reverberatory furnace, crude lead, tin-lead slag, dust materials, etc. are produced. The crude lead can be sent to the lead refining workshop to produce refined lead, the tin-lead slag can be used as the raw material for the next step of high-temperature strong reduction smelting of tin in an electric furnace, and the dust is returned to the batching. The crude lead produced contains 93.21% lead and 2.15% tin; while the tin-lead slag contains 6.85% lead, 35.43% tin, and 2.8% iron. 93% of the Pb element enters the crude lead, 5.1% enters the tin-lead slag; 6.6% of the tin element enters the crude lead, 89.4% enters the tin-lead slag;

[0051] 5) Electric furnace reduction smelting treatment: The tin-lead slag produced after reduction melting in the reverberatory furnace in step 4) is mixed with the reducing agent anthracite according to 1.03 times of the theoretical requirement, and fluxes such as limestone and quartzite are added according to the slag-forming requirements. The mixed materials are evenly mixed and fed into the furnace, the furnace temperature is 1250 - 1280 °C, and the negative pressure in the furnace is -80 - -120 Pa. After high-temperature strong reduction smelting in the electric furnace, the rich slag is sent to the fuming furnace, the tin-lead alloy is sent to the tin refining workshop for impurity removal and then vacuum separated to extract tin and lead, the produced dust is collected in sections, the high-tin dust is returned to the batching, and the low-tin dust is sent to the fuming furnace. The dry basis analysis (%) of the produced tin-lead alloy contains 13.76% lead and 84.29% tin; the rich slag contains 1.72% lead and 3.28% tin. 72.4% of the Pb element enters the tin-lead alloy, 8.5% enters the rich slag; 85.2% of the tin element enters the tin-lead alloy, 4.6% enters the rich slag, and the tin recovery rate is 97.9%.

[0052] Comparative example

[0053] The comparative example of the present invention is described by taking the raw material grouping of Example 2 as an example for the process of separating tin and lead: Take 3t of raw material soot (dry basis), the main components are: zinc 14.82%, lead 18.44%, Zn 15.4%, tin 8.83%, S 9.6, Fe 1.43, As 1.67; their main components are the same; Prepare 6m3 of sulfuric acid solution with a concentration of 60g / L in a 16m3 stirring tank, put the tin soot into it, stir and leach at a temperature of 60°C under normal pressure, and the end point is stabilized between pH 1.5 and 2, the leaching time is 4h. After the reaction is completed, the leached material is filtered by pressure to obtain a zinc and copper-containing filtrate and a tin and lead mixed filter residue. The zinc and copper-containing filtrate is sent to the zinc and copper production lines for treatment; the precipitation rates of tin and lead in the process are both greater than 95%. The tin and lead mixed filter residue enters the lead leaching process;

[0054] Put the tin and lead mixed filter residue into a stirring kettle containing 16m3 of NaCl brine with Cl≥180g / L according to a solid-liquid ratio of 1:10, stir and heat to 90°C, continue to stir at a constant temperature for 20min, pump the material after lead leaching into a filter press for pressure filtration to obtain a filter residue and a filtrate. The main components of the filter residue are tin Sn: 26.8%, Pb: 3.1%. The recovery rate of tin in the process is 90.5%, and the Pb in the tin slag is about 3.1%; it can be sold directly as a product; the filtrate is a mixed solution of lead chloride and sodium chloride, and the filtrate enters the lead removal process;

[0055] The lead removal process is also called the cooling process. The lead chloride sodium brine is exchanged heat through a heat exchanger and then put into a cooling cylinder. When the brine is cooled to a certain temperature, lead chloride slowly precipitates. When it is below 5°C and the Pb content in the brine is ≤3g / L, filter by pressure while it is cold. The slag is a by-product of lead chloride. The filtrate is the sodium chloride brine after lead removal. After exchanging heat through a heat exchanger, first add calcium chloride to remove sulfate radicals, and then add sodium chloride to make the brine reach Cl≥180g / L and put it back into the lead leaching process.

[0056] It can be seen from the process of the comparative example that there are the following deficiencies: First, the energy consumption is large. The 90°C brine needs to be cooled to below 5°C and then reheated to 90°C; Second, although there is a heat exchanger to exchange heat to make up for part of the heat loss, the filter often gets blocked due to crystal precipitation in the equipment and pipelines; Third, the lead cannot be removed completely, resulting in the subsequent lead leaching efficiency not reaching the expected effect, and the residual Pb content in the tin slag is as high as more than 3.1%, and the effect of separating lead and tin is not ideal.

Claims

1. A new process for separating tin and lead from low-grade tin, lead and zinc dust produced by a fuming furnace, using the low-tin and high-lead dust produced by treating low-tin materials by a fuming furnace sulfidation volatilization method as raw material, comprising the following steps: 1) Impurity removal and dezincification: The iron blocks, slag, cloth strips, stones and other impurities contained in the low-tin and high-lead dust raw materials are removed mechanically, and then the zinc removal is carried out by stirring leaching-washing process with dilute sulfuric acid solution to obtain impurity-removed zinc slag; 2) Desulfurization by adding a desulfurizing agent: adding a desulfurizing agent to the impurity-removing and zinc-removing slag in step 1) to carry out a desulfurizing solution reaction, and controlling the desulfurizing solution to have less residual desulfurizing agent in the desulfurized material after the reaction of the desulfurizing solution. After the reaction of the desulfurizing solution is completed, washing water ash is obtained by filter pressing; 3) Roasting desulfurization and dearsenicization: Dry the ash from the washing water in step 2 and remove sulfur, arsenic and antimony to produce tin-lead roasted sand, control the sulfur and arsenic content in the tin-lead roasted sand to be below 0.3-0.5wt%, respectively, and improve the tin-lead grade; 4) Reduction and melting out crude lead: a reverberatory furnace is used to carry out melting treatment on the tin-lead roasted sand in step 3), and the lead oxide in the tin-lead roasted sand is preferentially reduced by controlling the weak reducing atmosphere, temperature and slag type, and the melting treatment produces tin-lead slag, crude lead and smoke dust materials; the crude lead is sent to the lead refining workshop to produce refined lead, and the smoke dust materials are returned to the ingredients, and the tin-lead slag is the raw material for the next step of high-temperature strong reduction tin refining in an electric furnace; 5) Strong reduction smelting treatment in electric furnace: The tin-lead slag produced by the reduction smelting treatment in the reverberatory furnace in step 4) is subjected to strong reduction smelting treatment in an electric furnace, and the produced rich slag is sent to the fuming furnace, and the produced tin-lead alloy is sent to the tin refining workshop for impurity removal and vacuum separation to extract tin and lead products; and the produced smoke is collected in sections, the high-tin smoke is returned to the batching, and the low-tin smoke is sent to the fuming furnace.

2. According to claim 1, a new process for separating tin and lead from low-grade tin, lead and zinc smoke produced by a fuming furnace is characterized by: Step 1) The low-grade tin-lead-zinc smoke raw material contains: 18-30.5 wt% lead, 8-12.5 wt% tin; and the zinc content in the impurity-removing and dezincifying slag is controlled to be 1.0-2.5 wt%.

3. According to claim 1, a new process for separating tin and lead from low-grade tin, lead and zinc smoke produced by a fuming furnace is characterized by: Step 2) The desulfurizing agent is a mixed alkaline aqueous solution of sodium carbonate and / or sodium hydroxide.

4. A new process for separating tin and lead from low-grade tin, lead and zinc dust produced by a fuming furnace according to claim 1 or 2, characterized in that: Step 2) The conditions of the desulfurization reaction are: controlling the reaction time of the desulfurization solution to 55-70min, the reaction temperature to 65-75°C, and controlling the liquid-to-solid ratio of the desulfurization solution to 10:1-1.2 during the reaction; at the same time, controlling the mass molar ratio of sodium and lead to 1.1-1.2:1 during the reaction of the desulfurization solution, and controlling the residual rate of the desulfurizer in the slurry after the reaction and conversion of the desulfurization solution to 1-3g / L.

5. According to claim 1, a new process for separating tin and lead from low-grade tin, lead and zinc smoke produced by a fuming furnace is characterized by: Step 3) is to dry the washed ash and remove sulfur, arsenic and antimony to obtain tin-lead roasted sand, and control the sulfur and arsenic contents in the tin-lead roasted sand to be less than 0.3-0.5 wt% respectively; and control the process technology operation conditions: adding reducing coal to the raw materials, the roasting temperature is 820-980°C; and the oxidation / reduction roasting atmosphere during the roasting process is controlled to be a negative pressure of -12 to -16 Pa at the kiln tail.

6. According to claim 1, a new process for separating tin and lead from low-grade tin, lead and zinc dust produced by a fuming furnace, characterized in that: Step 4) The process and technical operating conditions of the smelting treatment are: controlling the furnace temperature of the reverberatory furnace reaction at 920-1050°C; and adding 5-10% of anthracite as a reducing agent and 0-5% of soda ash as a smelting agent in the reverberatory furnace mixed material.

7. According to claim 1, a new process for separating tin and lead from low-grade tin, lead and zinc smoke produced by a fuming furnace is characterized by: Step 5) The technical operating conditions of the electric furnace strong reduction smelting treatment process are to control the electric furnace strong reduction raw material smelting treatment temperature to 1220-1280°C; add anthracite or coke as a reducing agent according to the content of the added electric furnace material, and control the negative pressure in the electric furnace cavity to -65--150Pa.

8. A new process for separating tin and lead from low-grade tin, lead and zinc dust produced by a fuming furnace according to claim 7, characterized in that: The amount of anthracite and coke added as reducing agents is such that when the iron content in the tin-lead slag is below 3%, 2 to 4% of the theoretical amount of anthracite and coke is added; when the iron content in the tin-lead slag is 7% or more, 5% of the theoretical amount of anthracite and coke is added; at the same time, the negative pressure in the inner cavity of the electric furnace is controlled to be -70 to -120Pa.