Efficient lead-silver chemical separation method

Abstract

The invention relates to the technical field of non-ferrous metal resource recycling, in particular to an efficient lead and silver chemical separation method. The invention discloses an efficient lead and silver chemical separation method. The method comprises the following steps of acid solution leaching treatment, silver extraction agent extraction treatment, reducing agent reduction treatment, alkali solution dissolution treatment and precipitating agent or oxidizing agent precipitation treatment. According to the efficient lead and silver chemical separation method, copper, zinc, iron and other metals in the lead and silver residues are leached into the solution through the acid solution, then lead is leached into the solution through the alkali solution, efficient separation of lead and silver is achieved, the lead and silver separation efficiency can reach 90% or above, the lead and silver are made into corresponding products, the purity of the lead and silver products is high, the economic value is high, and the method is suitable for industrial production. And secondary pollution is avoided, the application range is wide, various lead-containing materials can be treated, resource waste is reduced, energy consumption is low, and the method is suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal resource recycling, and in particular to a method for efficient lead-silver chemical separation. Background Art

[0002] In the field of metal smelting and recycling, the separation technology of lead and silver has always been a hot topic and difficult point of research. As important metal resources, lead and silver are widely used in many industries such as electronics, chemicals, medical treatment, and jewelry. However, since lead and silver often exist in the form of symbiotic minerals in nature and have certain similarities in chemical properties, their efficient separation becomes particularly complex and challenging.

[0003] In addition to extracting lead and silver directly from ores, extracting lead and silver from smelting slag and waste resources in various metal smelting workshops is also a very important means of obtaining lead and silver. However, the mineral resources in such waste resources are very complex and have a very low grade, often only 1-2%, or even less, which has caused great obstacles to the extraction of lead and silver from secondary mineral resources.

[0004] For example, Xiang Ping used the "flotation-magnetic separation-gravity separation" combined mineral processing technology in the "Technical and Theoretical Research on the Separation of Manganese, Lead and Silver in Zinc Electrolytic Anode Mud" to obtain lead concentrate with 60.89% lead content and silver concentrate with 48515g / t silver content from electrolytic zinc anode mud with lead and silver grades of 21.4% and 1628g / t respectively. However, this method is complex and costly, and requires a large amount of flotation agents. The subsequent recovery and treatment of flotation agents also require huge cost investment, and is also prone to secondary pollution.

[0005] Patent CN 107661813 A discloses "a method for comprehensive recovery of silver, lead and iron from electrostatic precipitator ash". This method uses a water washing-flotation method to obtain a mixed concentrate with a lead grade of >25% and a silver grade of >800 g / t from the electrostatic precipitator ash. However, the mixed concentrate obtained by this method has a low grade and does not achieve separation of lead and silver. It still needs to be sent to a smelting workshop for extraction and recovery of lead and silver.

[0006] Patent CN 104846211 A discloses "a method for separating zinc, cadmium, copper, lead and silver from zinc smelting copper slag". This method uses oxygen pressure leaching and normal pressure leaching to leach zinc, cadmium and copper in the zinc smelting slag into a solution system to obtain a mixed concentrate with a lead content of 20-50% and a silver content of 400-1000g / t, which is then sent to a smelting system to recover lead and silver. This method uses two acid leachings to obtain a mixed concentrate, but still uses pyrometallurgical smelting to recover lead and silver, resulting in a waste of resources and environmental pollution.

[0007] Patent CN 108277357 A discloses "a method for separating and recovering silver and lead from dust removal ash from sintering machine heads in a steel plant". This method uses ammonium carbonate and ammonium chloride to leach lead and silver from the machine head ash into a solution in two steps, and then obtains sponge silver through displacement, which is then cooled and crystallized to obtain lead chloride. However, this method is complicated to operate, and a large amount of ammonium ions are introduced, resulting in a harsh operating environment.

[0008] In summary, most of the recovery and utilization of lead and silver resources is to obtain mixed concentrates through flotation, and then send them to the smelting system to recover lead and silver. This process has a large processing capacity, but the recovery rate of lead and silver is not high, which will cause waste of resources and environmental pollution. The wet method of recovering lead and silver resources is to leach lead and silver into the solution system, and then obtain silver and lead products through methods such as replacement, cooling and crystallization. Lead and silver can be directly separated, and the energy consumption is low, but the operation is complicated, the conditions are harsh, the operating environment is bad, and it is difficult to achieve large-scale production.

[0009] To this end, the present application provides a method for highly efficient, pollution-free and efficient lead-silver chemical separation. Summary of the invention

[0010] In order to overcome the shortcomings of the prior art, the present invention provides a method for efficient chemical separation of lead and silver, which utilizes an acid solution to leach metals such as copper, zinc, and iron in lead-silver slag into a solution, and then utilizes an alkaline solution to leach lead into the solution, thereby achieving efficient separation of lead and silver, the lead and silver separation efficiency can reach more than 90%, and lead and silver are made into corresponding products, the lead and silver products have high purity and high economic value, and do not generate secondary pollution, have a wide range of applications, can process various lead-containing materials, reduce waste of resources, have low energy consumption, and are suitable for large-scale production.

[0011] A method for efficient lead-silver chemical separation comprises the following steps: S1. Acid solution leaching treatment Using an acid solution to leach the lead-silver slag, performing solid-liquid separation, and obtaining lead-silver enriched slag; S2. Silver Extraction Treatment Using a silver extracting agent to extract silver from the lead-silver enriched slag to obtain a silver-containing solution and a lead-containing solid; S3. Reducing agent reduction treatment Adding a reducing agent to the silver-containing solution to carry out a reduction reaction, after the reaction is completed, solid-liquid separation is performed to obtain crude silver, and then high-temperature smelting is performed to obtain a silver ingot; S4. Alkaline solution dissolution treatment Dissolving the lead-containing solid using an alkaline solution to obtain a lead-containing solution and lead slag; S5. Precipitant or oxidant precipitation treatment A reducing agent is added to the lead-containing solution to recover the silver therein, thereby obtaining a lead-enriched solution and crude silver; and a precipitant or an oxidant is added to the lead-enriched solution to obtain a lead product.

[0012] In some embodiments, in step S1, the lead-silver slag is zinc electrolysis anode mud, steel dust removal ash treatment slag, lead, silver, copper smelting slag; The acid solution is a sulfuric acid solution or a hydrochloric acid solution.

[0013] In some embodiments, in step S1, an oxidant is further added, and the oxidant is one or more of hydrogen peroxide, chlorine, sodium hypochlorite, calcium hypochlorite, and chlorine dioxide.

[0014] In some embodiments, in step S2, the silver-extracting agent is composed of sodium thiosulfate and alkaline thiourea, and the liquid-solid ratio of the silver-extracting agent to the lead-silver enriched slag is 2-5:1.

[0015] In some embodiments, in step S2, the reaction temperature is room temperature, and the pH of the solution system is maintained at 11-14 during the reaction.

[0016] In some embodiments, in step S3, the reducing agent is one or more of formaldehyde, glucose, hydrogen peroxide, sodium sulfite, and sulfur dioxide, the amount of the reducing agent added is 100-150% of the molar amount of silver ions in the solution, the temperature of the reduction reaction is 20-70°C, and the time of the reduction reaction is 0.5-1.5h.

[0017] In some embodiments, in step S3, the crude silver smelting temperature is 1000-1200°C.

[0018] In some embodiments, in step S4, the alkaline solution is one or more of sodium hydroxide solution, potassium hydroxide solution, ammonium carbonate solution, and sodium carbonate solution, the concentration of the alkaline solution is 5-10 mol / L, the liquid-to-solid ratio is maintained at 5-10:1 during dissolution, the dissolution temperature is 70-90°C, and the dissolution time is 1-5h.

[0019] In some embodiments, in step S5, the reducing agent used is one or more of glucose, hydrogen peroxide, and formaldehyde, the amount of reducing agent added is 100-150% of the molar amount of silver ions in the solution, the reduction temperature is 20-70°C, and the reduction time is 0.5-1.5h.

[0020] In some embodiments, in step S5, the precipitant used is one or more of CO2, sodium carbonate, sodium hydroxide, and oxalic acid, the amount of the precipitant added is 100-150% of the molar amount of lead ions in the lead-enriched solution, and the precipitation time is 0.5-1.5h; the oxidant is one or more of hydrogen peroxide and chlorine, and the amount of the oxidant added is 100-120% of the molar amount of lead ions in the lead-enriched solution.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The method for efficient chemical separation of lead and silver described in the present application achieves preliminary separation of lead and silver by leaching soluble metals in lead-silver slag with an acid solution (sulfuric acid or hydrochloric acid); extracting silver from lead-silver enriched slag with a silver extracting agent composed of sodium thiosulfate and alkaline thiourea; adding a reducing agent (such as formaldehyde, glucose, etc.) to the silver-containing solution to reduce silver ions to silver atoms to form crude silver; using an alkaline solution (such as sodium hydroxide, etc.) to dissolve the lead-containing solid to obtain a lead-containing solution; adding a precipitant or oxidant to the lead-enriched solution to obtain a lead product; achieving efficient separation of lead and silver, with a separation efficiency of more than 90%.

[0022] 2. Compared with traditional pyrometallurgy, the method for efficient lead-silver chemical separation described in the present application is simpler to operate and easier to control; through the chemical separation and reduction process, the silver ingots and lead products obtained are of high purity and high economic value; and it is suitable for the recovery and utilization of various lead-containing materials such as electrolytic zinc anode mud, lead-silver smelting slag, and steel smelting ash. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0024] Figure 1 This is a process flow chart of a method for efficient lead-silver chemical separation described in this application. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0026] As used herein, "and / or" includes the term of all combinations of any one or more associated listed items. The terms used herein are only used to describe specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It is further understood that "including", when used in this specification, specifies the stated features, integers, steps, operations, elements and / or compositions, but does not exclude the existence or addition of one or more other features, integers, steps, operations, elements, compositions and / or combinations thereof.

[0027] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. It is further understood that terms, such as defined in commonly used dictionaries, are interpreted in accordance with their meanings in the context of the relevant art and are not idealized or overly formal meanings unless explicitly defined as such herein.

[0028] The exemplary invention described herein may appropriately lack any one or more element limitations that are not specifically disclosed herein. Therefore, the terms "comprise", "include", "contain", etc. should be understood broadly and non-restrictively. In addition, the terminology used herein is used as a description, not a limitation, and it is unintentional to use these terminology expressions that do not include any equivalent characteristics, but only describe some of their characteristics, but various modifications are possible within the scope of the present invention according to the rights. Therefore, although the present invention has been specifically disclosed by preferred embodiments and optional features, the modifications disclosed herein to embody the changes of the present invention may be recorded by those skilled in the art, and such modifications and changes will be considered to be within the scope of the present invention.

[0029] Terminology explanation: Lead-silver slag refers to waste or smelting slag containing metals such as lead and silver. These wastes often contain other metal elements such as copper, zinc and iron.

[0030] In view of the problems that lead and silver are difficult to be separated efficiently in traditional methods, resource utilization is low, and energy consumption and pollution are serious during pyrometallurgy, the present application provides a method for efficient chemical separation of lead and silver, comprising the following steps: S1. Acid solution leaching treatment Using an acid solution to leach the lead-silver slag, performing solid-liquid separation, and obtaining lead-silver enriched slag; S2. Silver Extraction Treatment Using a silver extracting agent to extract silver from the lead-silver enriched slag to obtain a silver-containing solution and a lead-containing solid; S3. Reducing agent reduction treatment Adding a reducing agent to the silver-containing solution to carry out a reduction reaction, after the reaction is completed, solid-liquid separation is performed to obtain crude silver, and then high-temperature smelting is performed to obtain a silver ingot; S4. Alkaline solution dissolution treatment Dissolving the lead-containing solid using an alkaline solution to obtain a lead-containing solution and lead slag; S5. Precipitant or oxidant precipitation treatment A reducing agent is added to the lead-containing solution to recover the silver therein, thereby obtaining a lead-enriched solution and crude silver; and a precipitant or an oxidant is added to the lead-enriched solution to obtain a lead product.

[0031] In some embodiments, in step S1, the lead-silver slag is a secondary mineral source such as zinc electrolysis anode mud, steel dust removal ash treatment slag, lead, silver, copper smelting slag, etc.; the acid solution is a sulfuric acid solution or a hydrochloric acid solution. In step S1, an oxidant is also added, and the oxidant is one or more of hydrogen peroxide, chlorine, sodium hypochlorite, calcium hypochlorite, and chlorine dioxide.

[0032] In the present application, the lead-silver slag generally contains a variety of metal elements, among which copper, zinc, iron and other metals have a high solubility in the acid solution, while the solubility of lead and silver is relatively low. By selecting an appropriate acid solution (such as sulfuric acid or hydrochloric acid), under the conditions of appropriate concentration, temperature, liquid-solid ratio and adding an appropriate amount of oxidant, the soluble metals in the lead-silver slag can be effectively leached into the solution, while lead and silver remain in the solid in the form of insoluble compounds.

[0033] Specifically, in step S1, an acid solution is used to leach out soluble metals (such as copper, zinc, iron, etc.) in the lead-silver slag, while lead and silver are retained in the solid in the form of precipitation, so that the subsequent steps can more specifically separate lead and silver. This step is the premise and basis for achieving efficient lead-silver chemical separation.

[0034] Specifically, step S1: select a sulfuric acid or hydrochloric acid solution with a concentration of 2-5 mol / L as a leaching agent; mix the lead-silver slag with the acid solution at a liquid-solid ratio of 2-5:1, and stir for 1-3 hours at a temperature range of 20-70 degrees Celsius; add an appropriate amount of oxidant (such as hydrogen peroxide, chlorine, sodium hypochlorite, calcium hypochlorite, chlorine dioxide, etc.) during the leaching process to improve the leaching efficiency, and the amount of oxidant added is 1%-10%. After the leaching is completed, the solid is separated from the solution by a centrifuge or other equipment to obtain lead-silver enriched slag.

[0035] In some embodiments, in step S2, the silver extracting agent is composed of sodium thiosulfate and alkaline thiourea, and the weight ratio of sodium thiosulfate and alkaline thiourea in the silver extracting agent is 1:3; the liquid-solid ratio of the silver extracting agent to the lead-silver enriched slag is 2-5:1; the reaction temperature is room temperature, and the pH of the solution system is maintained at 11-14 during the reaction.

[0036] In the present application, in step S2, the lead-silver enriched slag obtained in step S1 is mixed with an appropriate amount of silver extracting agent, and the pH value of the solution system is adjusted as needed; at room temperature, the silver extracting agent is stirred for a long time (24-36 hours) to fully react with the silver in the lead-silver enriched slag. During the reaction, silver gradually transfers from the solid phase to the liquid phase to form a silver-containing solution. After the reaction is completed, the silver-containing solution is separated from the lead-containing solid by solid-liquid separation technology (such as filtration, centrifugation, etc.). Through step S2, silver is enriched in the liquid phase, providing conditions for subsequent refining.

[0037] Specifically, the silver extracting agent is a solid, composed of sodium thiosulfate and alkaline thiourea. The weight ratio of sodium thiosulfate and alkaline thiourea in the silver extracting agent is 1:3. These two compounds have a strong coordination ability for silver ions. They can form stable complexes with silver ions, thereby effectively transferring silver from the solid phase (such as lead-silver enriched slag) to the liquid phase. The silver extracting agent has a high selectivity for silver and extracts it at a pH value between 11-14, while it has a low reactivity to other metal ions such as lead. This selectivity ensures that the silver extracting agent mainly acts on silver during the extraction process, thereby improving the extraction efficiency of silver.

[0038] In some embodiments, in step S3, the reducing agent is one or more of formaldehyde, glucose, hydrogen peroxide, sodium sulfite, and sulfur dioxide, the amount of the reducing agent added is 100-150% of the molar amount of silver ions in the solution, the temperature of the reduction reaction is 20-70°C, and the time of the reduction reaction is 0.5-1.5h. The crude silver smelting temperature is 1000-1200°C.

[0039] In the present application, in step S3, a suitable reducing agent is added to the silver-containing solution to reduce the silver ions (Ag + ) is reduced to metallic silver (Ag), and silver is extracted and purified from the silver-containing solution to obtain a crude silver product.

[0040] In some embodiments, in step S4, the alkaline solution is one or more of sodium hydroxide solution, potassium hydroxide solution, ammonium carbonate solution, and sodium carbonate solution, the concentration of the alkaline solution is 5-10 mol / L, the liquid-to-solid ratio is maintained at 5-10:1 during dissolution, the dissolution temperature is 70-90°C, and the dissolution time is 1-5h.

[0041] In the present application, the lead-containing solid obtained in step S2 is further processed, and the lead-containing solid is dissolved by an alkaline solution, so that the lead element can be transferred from the solid to the solution to recover the lead element therein and remove the remaining impurities. This step is one of the key links to achieve efficient separation of lead and silver, ensuring the maximum recovery of lead resources.

[0042] Specifically, the process of step S4 is: selecting an appropriate alkaline solution (such as sodium hydroxide solution, potassium hydroxide solution, ammonium carbonate solution or sodium carbonate solution) and adjusting it to a desired concentration (usually 5-10 mol / L); mixing the lead-containing solid obtained in step S2 with the alkaline solution in a certain proportion (the liquid-to-solid ratio is usually 5-10:1), stirring and dissolving at a set temperature (70-90° C.) for a certain time (1-5 h), during which the lead element is transferred from the solid to the solution to form a lead-containing solution; After the dissolution is completed, the lead-containing solution is separated from the undissolved lead slag by solid-liquid separation technology (such as filtration, centrifugation, etc.). The lead slag mainly contains unreacted solid impurities and a small amount of undissolved lead compounds, which can be returned to step S4 for further dissolution or other treatment; the obtained lead-containing solution enters the next step (such as step S5) for further lead recovery and purification.

[0043] Therefore, in step S4, dissolving the lead-containing solid by an alkaline solution can efficiently transfer the lead element from the solid to the solution, thereby improving the recovery rate of lead.

[0044] In some embodiments, in step S5, the reducing agent used is one or more of glucose, hydrogen peroxide, and formaldehyde, the amount of reducing agent added is 100-150% of the molar amount of silver ions in the solution, the reduction temperature is 20-70°C, and the reduction time is 0.5-1.5h. The precipitating agent used is one or more of CO2, sodium carbonate, sodium hydroxide, and oxalic acid, the amount of precipitating agent added is 100-150% of the molar amount of lead ions in the lead-enriched solution, and the precipitation time is 0.5-1.5h; the oxidizing agent is one or more of hydrogen peroxide and chlorine, and the amount of oxidizing agent added is 100-120% of the molar amount of lead ions in the lead-enriched solution.

[0045] In the present application, the difference in chemical properties between silver and lead is used to reduce the silver ions in the lead-containing solution to metallic silver through a reduction reaction, and at the same time, the lead ions are converted into a precipitable or oxidizable form by a precipitation reaction or an oxidation reaction, thereby achieving the separation of lead and silver. Specifically, reducing agents such as glucose, hydrogen peroxide, formaldehyde, etc. can selectively reduce the silver ions in the solution, while precipitants or oxidants are used to convert lead ions into precipitates or oxides for subsequent treatment and recovery.

[0046] Specifically, the process of step S5 is to add an appropriate amount of reducing agent (such as glucose, hydrogen peroxide, formaldehyde, etc.) to the lead-containing solution obtained in step S4, so that the silver ions in the solution are reduced to metallic silver; the amount of reducing agent added is usually 100%-150% of the molar amount of silver ions in the solution to ensure that the silver ions are fully reduced, and the reduction reaction is carried out at room temperature for 0.5-1.5 hours; after the reaction is completed, the crude silver and lead enriched solution are obtained by solid-liquid separation. The obtained crude silver is returned to step S3 for high-temperature smelting to obtain a silver ingot with higher purity. This step is intended to improve the purity of the silver product and facilitate subsequent processing and use.

[0047] A precipitant (such as CO2, sodium carbonate, sodium hydroxide, oxalic acid, etc.) or an oxidant (such as hydrogen peroxide, chlorine, etc.) is added to the lead-enriched solution to convert the lead ions into precipitates or oxides; the amount of the precipitant added is usually 100%-150% of the molar amount of lead ions in the lead-enriched solution to ensure that the lead ions are completely precipitated. The precipitation reaction or oxidation reaction is carried out at room temperature and the reaction time is 0.5-1.5 hours. After the reaction is completed, the lead product (such as lead carbonate, lead dioxide, etc.) is obtained by solid-liquid separation.

[0048] Therefore, in step S5, the combination of reduction reaction and precipitation reaction or oxidation reaction realizes the efficient separation of lead and silver, and the separation efficiency can reach more than 90%, which significantly improves the resource recovery rate. Through solid-liquid separation and high-temperature smelting, the obtained silver ingots and lead products have high purity and high economic value, which can meet the use requirements of different fields.

[0049] The following examples and comparative examples further illustrate the method for efficient lead-silver chemical separation described in the present application. Example 1

[0050] The content of lead-silver slag after dust removal in the sintering workshop of a steel plant is shown in Table 1 below: Table 1 Composition of lead-silver slag after dust removal

[0051] As shown in Table 1, the acid-soluble metals in lead-silver slag are mainly copper, iron and zinc. A method for efficient lead-silver chemical separation comprises the following steps: The lead-silver slag was leached with a 2 mol / L sulfuric acid solution at a liquid-solid ratio of 2:1. The oxidant was hydrogen peroxide at a rate of 1%. After stirring at room temperature for 1 hour, the leached slurry was placed in a centrifuge and centrifuged at 3000 r / min for 5 minutes. The solid after centrifugation was the lead-silver enriched slag, and its composition is shown in Table 2 below.

[0052] Table 2 Composition of lead-silver enriched slag

[0053] As shown in Table 2, the silver content is 0.84% ​​(8400g / t). Silver is leached from lead-silver enriched slag using a silver extracting agent. Leaching begins after adjusting the system pH to 11. The liquid-solid ratio is maintained at 2:1 during leaching. The leaching temperature is room temperature. The leaching time is 24h. After leaching, solid-liquid separation is performed to obtain a silver-containing solution and a lead-containing solid. Glucose is added to the silver-containing solution. The amount of glucose added is 100% of the molar amount of silver ions in the solution. Stir and reduce at 20°C for 0.5h. After the reaction is completed, solid-liquid separation is performed to obtain crude silver. The crude silver is smelted at 1000°C to obtain a silver ingot. The composition of the lead-containing solid component is shown in Table 3 below.

[0054] Table 3 Composition of lead-containing solids

[0055] As shown in Table 3, the main component of the lead-containing solid is lead sulfate. A 5 mol / L sodium hydroxide solution is used to dissolve the lead in the lead-containing solid into the solution. The liquid-solid ratio is maintained at 5:1 during the dissolution process. The dissolution temperature is 70°C and the dissolution time is 1 hour. After the reaction is completed, solid-liquid separation is performed to obtain a lead-containing solution and lead slag. The composition of the lead-containing solution is shown in Table 4 below, and the composition of the lead slag is shown in Table 5 below.

[0056] Table 4 Composition of lead solution

[0057] Table 5 Composition of lead slag

[0058] As shown in Table 4, glucose was used to reduce silver ions in the lead-containing solution. The amount of glucose added was 100% of the molar amount of silver ions in the solution. The reduction was stirred at 20°C for 0.5h. After the reaction was completed, solid-liquid separation was performed to obtain lead-enriched solution and crude silver. The crude silver was smelted at 1000°C to obtain silver ingots. The composition of the lead-enriched solution is shown in Table 6 below.

[0059] Table 6 Composition of lead enriched solution

[0060] As shown in Table 6, carbon dioxide is used as a precipitant to prepare lead carbonate precipitation, carbon dioxide is introduced into the lead enriched solution, stirred at room temperature for 0.5 h, and solid-liquid separation is performed after the reaction is completed to obtain a lead carbonate product. Hydrogen peroxide can also be added for oxidation, the amount of hydrogen peroxide added is 100% of the molar amount of lead ions in the lead enriched solution, the oxidation time at room temperature is 0.5 h, and solid-liquid separation is performed after the reaction is completed to obtain a lead dioxide product. Example 2

[0061] The content of lead-silver slag after dust removal in the sintering workshop of a steel plant is shown in Table 7 below: Table 7 Composition of lead-silver slag after dust removal

[0062] As shown in Table 7, the acid-soluble metals in lead-silver slag are mainly copper, iron and zinc. A method for efficient lead-silver chemical separation comprises the following steps: The lead-silver slag was leached with a 4 mol / L sulfuric acid solution at a liquid-to-solid ratio of 4:1. An oxidant, hydrogen peroxide, was added at a rate of 5%. After stirring at room temperature for 2 hours, the leached slurry was placed in a centrifuge and centrifuged at 3000 r / min for 5 minutes. The solid after centrifugation was the lead-silver enriched slag, and its composition is shown in Table 8 below.

[0063] Table 8 Composition of lead-silver enriched slag

[0064] As shown in Table 8, the silver content is 0.71% (7100g / t). Silver is leached from lead-silver enriched slag using a silver extracting agent. Leaching begins after adjusting the system pH to 12. The liquid-solid ratio is maintained at 4:1 during leaching. The leaching temperature is room temperature. The leaching time is 30h. After leaching, solid-liquid separation is performed to obtain a silver-containing solution and a lead-containing solid. Glucose is added to the silver-containing solution in an amount of 120% of the molar amount of silver ions in the solution. Stir and reduce at 50°C for 1h. After the reaction is completed, solid-liquid separation is performed to obtain crude silver. The crude silver is smelted at 1100°C to obtain a silver ingot. The composition of the lead-containing solid component is shown in Table 9 below.

[0065] Table 9 Composition of lead-containing solids

[0066] As shown in Table 9, the main component of the lead-containing solid is lead sulfate. 8 mol / L sodium hydroxide solution is used to dissolve the lead in the lead-containing solid into the solution. The liquid-solid ratio is maintained at 8:1 during the dissolution process. The dissolution temperature is 80°C and the dissolution time is 3 hours. After the reaction is completed, solid-liquid separation is performed to obtain a lead-containing solution and lead slag. The composition of the lead-containing solution is shown in Table 9.

[0067] Table 10 Composition of lead solution

[0068] As shown in Table 10, glucose was used to reduce silver ions in the lead-containing solution, the amount of glucose added was 120% of the molar amount of silver ions in the solution, and the reduction was stirred at 50°C for 1 hour. After the reaction was completed, solid-liquid separation was performed to obtain lead-enriched solution and crude silver. The crude silver was smelted at 1000°C to obtain silver ingots. The composition of the lead-enriched solution is shown in Table 11 below. The composition of the lead slag is shown in Table 12 below.

[0069] Table 11 Composition of lead enriched solution

[0070] Table 12 Composition of lead slag

[0071] As shown in Table 11, carbon dioxide is used as a precipitant to prepare lead carbonate precipitation, carbon dioxide is introduced into the lead enriched solution, stirred at room temperature for 1 hour, and solid-liquid separation is performed after the reaction is completed to obtain a lead carbonate product. Hydrogen peroxide can also be added for oxidation, the amount of hydrogen peroxide added is 110% of the molar amount of lead ions in the lead enriched solution, the oxidation time is 1 hour at room temperature, and solid-liquid separation is performed after the reaction is completed to obtain a lead dioxide product. Example 3

[0072] The content of lead-silver slag after dust removal in the sintering workshop of a steel plant is shown in Table 13 below: Table 13 Composition of lead-silver slag after dust removal

[0073] As shown in Table 13, the acid-soluble metals in lead-silver slag are mainly copper, iron, and zinc; A method for efficient lead-silver chemical separation comprises the following steps: The lead-silver slag was leached with a 5 mol / L sulfuric acid solution at a liquid-to-solid ratio of 5:1. An oxidant, hydrogen peroxide, was added at a rate of 10%. After stirring at room temperature for 3 hours, the leached slurry was placed in a centrifuge and centrifuged at 3000 r / min for 5 minutes. The solid after centrifugation was the lead-silver enriched slag, and its composition is shown in Table 14 below.

[0074] Table 14 Composition of lead-silver enriched slag

[0075] As shown in Table 14, the silver content is 0.77% (7700g / t). Silver is leached from the lead-silver enriched slag using a silver extracting agent. Leaching begins after the pH of the system is adjusted to 14. The liquid-solid ratio is maintained at 5:1 during leaching. The leaching temperature is room temperature. The leaching time is 36 hours. After leaching, solid-liquid separation is performed to obtain a silver-containing solution and a lead-containing solid. Glucose is added to the silver-containing solution. The amount of glucose added is 150% of the molar amount of silver ions in the solution. Stir and reduce at 70°C for 1.5 hours. After the reaction is completed, solid-liquid separation is performed to obtain crude silver. The crude silver is smelted at 1200°C to obtain a silver ingot. The composition of the lead-containing solid component is shown in Table 15.

[0076] Table 15 Composition of lead-containing solids

[0077] As shown in Table 15, the main component of the lead-containing solid is lead sulfate. A 10 mol / L sodium hydroxide solution is used to dissolve the lead in the lead-containing solid into the solution. The liquid-solid ratio is maintained at 10:1 during the dissolution process. The dissolution temperature is 90°C and the dissolution time is 5 hours. After the reaction is completed, solid-liquid separation is performed to obtain a lead-containing solution and lead slag. The composition of the lead-containing solution is shown in Table 16 below.

[0078] Table 16 Composition of lead solution

[0079] As shown in Table 16, glucose was used to reduce silver ions in the lead-containing solution, the amount of glucose added was 150% of the molar amount of silver ions in the solution, and the reduction was stirred at 70°C for 1.5 hours. After the reaction was completed, solid-liquid separation was performed to obtain lead-enriched solution and crude silver. The crude silver was smelted at 1000°C to obtain silver ingots. The composition of the lead-enriched solution is shown in Table 17. The composition of the lead slag is shown in Table 18.

[0080] Table 17 Composition of lead enriched solution

[0081] Table 18 Composition of lead slag

[0082] As shown in Table 17, carbon dioxide is used as a precipitant to prepare lead carbonate precipitation, carbon dioxide is introduced into the lead enriched solution, stirred at room temperature for 1.5 hours, and solid-liquid separation is performed after the reaction is completed to obtain a lead carbonate product. Hydrogen peroxide can also be added for oxidation, the amount of hydrogen peroxide added is 120% of the molar amount of lead ions in the lead enriched solution, the oxidation time at room temperature is 1.5 hours, and solid-liquid separation is performed after the reaction is completed to obtain a lead dioxide product.

[0083] The silver ingots and lead dioxide products obtained in Examples 1-3 were tested for purity, and the test results are shown in Table 19 below.

[0084] Table 19 Test results of Example 1-Example 3

[0085] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A method for efficient chemical separation of lead and silver, characterized in that: The following steps are involved: S1. Acid solution leaching treatment Using an acid solution to leach the lead-silver slag, performing solid-liquid separation, and obtaining lead-silver enriched slag; S2. Silver Extraction Treatment Using a silver extracting agent to extract silver from the lead-silver enriched slag to obtain a silver-containing solution and a lead-containing solid; S3. Reducing agent reduction treatment Adding a reducing agent to the silver-containing solution to carry out a reduction reaction, after the reaction is completed, solid-liquid separation is performed to obtain crude silver, and then high-temperature smelting is performed to obtain a silver ingot; S4. Alkaline solution dissolution treatment Dissolving the lead-containing solid using an alkaline solution to obtain a lead-containing solution and lead slag; S5. Precipitant or oxidant precipitation treatment A reducing agent is added to the lead-containing solution to recover the silver therein, thereby obtaining a lead-enriched solution and crude silver; and a precipitant or an oxidant is added to the lead-enriched solution to obtain a lead product.

2. The method according to claim 1, characterized in that In step S1, the lead-silver slag is zinc electrolysis anode mud, steel dust removal ash treatment slag, lead, silver, copper smelting slag; The acid solution is a sulfuric acid solution or a hydrochloric acid solution.

3. The method according to claim 1, characterized in that In step S1, an oxidant is also added, and the oxidant is one or more of hydrogen peroxide, chlorine, sodium hypochlorite, calcium hypochlorite, and chlorine dioxide.

4. The method according to claim 1, characterized in that: In step S2, the silver-extracting agent is composed of sodium thiosulfate and alkaline thiourea, and the liquid-to-solid ratio of the silver-extracting agent to the lead-silver enriched slag is 2-5:

1.

5. The method according to claim 1, characterized in that In step S2, the reaction temperature is room temperature, and the pH of the solution system is maintained at 11-14 during the reaction.

6. The method according to claim 1, characterized in that In step S3, the reducing agent is one or more of formaldehyde, glucose, hydrogen peroxide, sodium sulfite, and sulfur dioxide, the amount of the reducing agent added is 100-150% of the molar amount of silver ions in the solution, the temperature of the reduction reaction is 20-70°C, and the time of the reduction reaction is 0.5-1.5h.

7. The method according to claim 1, characterized in that In step S3, the crude silver is smelted at a temperature of 1000-1200°C.

8. The method according to claim 1, characterized in that In step S4, the alkaline solution is one or more of sodium hydroxide solution, potassium hydroxide solution, ammonium carbonate solution, and sodium carbonate solution, the concentration of the alkaline solution is 5-10 mol / L, the liquid-to-solid ratio is maintained at 5-10:1 during dissolution, the dissolution temperature is 70-90°C, and the dissolution time is 1-5h.

9. The method according to claim 1, characterized in that: In step S5, the reducing agent used is one or more of glucose, hydrogen peroxide, and formaldehyde, the amount of reducing agent added is 100-150% of the molar amount of silver ions in the solution, the reduction temperature is 20-70° C., and the reduction time is 0.5-1.5 h.

10. The method according to claim 1, characterized in that In step S5, the precipitant used is one or more of CO2, sodium carbonate, sodium hydroxide, and oxalic acid, the amount of the precipitant added is 100-150% of the molar amount of lead ions in the lead-enriched solution, and the precipitation time is 0.5-1.5h; the oxidant is one or more of hydrogen peroxide and chlorine, and the amount of the oxidant added is 100-120% of the molar amount of lead ions in the lead-enriched solution.

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