A method for efficient chemical separation of lead and silver

Abstract

The present invention relates to the technical field of recycling of non-ferrous metal resources, and particularly relates to a method for efficient chemical separation of lead and silver. The present application discloses a method for efficient chemical separation of lead and silver, comprising the following steps: acid solution leaching treatment, silver extractant extraction treatment, reducing agent reduction treatment, alkali solution dissolution treatment, and precipitant or oxidant precipitation treatment. The method for efficient chemical separation of lead and silver described in the present application uses an acid solution to leach metals such as copper, zinc, and iron in the lead-silver slag into the solution, and then uses an alkali solution to leach lead into the solution, achieving efficient separation of lead and silver. The separation efficiency of lead and silver can reach over 90%. Moreover, lead and silver are made into corresponding products with high purity and high economic value, without generating secondary pollution, having a wide application range, being able to process various lead-containing materials, reducing waste of resources, having low energy consumption, and being suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling non-ferrous metal resources, and particularly to a method for efficient chemical separation of lead and silver. Background Art

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

[0003] In addition to directly extracting lead and silver from ores, extracting lead and silver from the smelting slag and waste resources in each metal smelting workshop is also a very important means to obtain lead and silver. However, the mineral resource components in such waste resources are very complex and the grade is very low, 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 combined beneficiation technology of "flotation - magnetic separation - gravity separation" in the "Technical and Theoretical Research on the Separation of Manganese, Lead, and Silver in Zinc Electrolysis Anode Sludge" to obtain a lead concentrate containing 60.89% lead and a silver concentrate containing 48515 g / t silver from the zinc electrolysis anode sludge with lead and silver grades of 21.4% and 1628 g / t respectively. However, this method has a complex process, high cost, requires a large amount of flotation reagents, and the subsequent recovery and treatment of flotation agents also involve huge cost inputs and are prone to cause secondary pollution.

[0005] Patent CN 107661813 A discloses "A Method for Comprehensive Recovery of Silver, Lead, and Iron from Electric Precipitation Ash". This method uses the method of water washing - flotation to obtain a mixed concentrate with a lead grade > 25% and a silver grade > 800 g / t from the electric precipitation ash. However, the grade of the mixed concentrate obtained by this method is relatively low, and the separation of lead and silver is not achieved. Subsequently, it still needs to be sent to the smelting workshop for the extraction and recovery of lead and silver.

[0006] Patent CN 104846211 A discloses "A Method for Separating Zinc, Cadmium, Copper, and Lead Silver from Copper Slag in Zinc Smelting". This method leaches zinc, cadmium, and copper in the zinc smelting slag into the solution system through oxygen pressure leaching and atmospheric pressure leaching to obtain a mixed concentrate with a lead grade of 20 - 50% and a silver grade of 400 - 1000 g / t, and then sends it to the smelting system to recover lead and silver. This method uses two acid leaching processes to obtain the mixed concentrate, but still uses pyrometallurgy to smelt and recover lead and silver, resulting in waste of resources and environmental pollution.

[0007] Patent CN 108277357 A discloses "a method for separating and recovering silver and lead from sintering machine head dust in a steel plant". This method uses two-step leaching with ammonium carbonate and ammonium chloride to leach lead and silver in the head dust into the solution, and then sponge silver is obtained through replacement, and lead chloride is obtained through cooling crystallization. However, this method has complex operations, introduces a large amount of ammonium ions, and has a harsh operating environment.

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

[0009] Therefore, this application provides a method for efficient and pollution-free chemical separation of lead and silver. Summary of the Invention

[0010] In order to overcome the deficiencies of the prior art, the present invention provides a method for efficient chemical separation of lead and silver. An acid solution is used to leach metals such as copper, zinc, and iron in lead-silver slag into the solution, and then an alkali solution is used to leach lead into the solution, achieving efficient separation of lead and silver. The separation efficiency of lead and silver can reach more than 90%. Moreover, lead and silver are made into corresponding products, with high purity and high economic value of the lead and silver products, no secondary pollution is generated, the applicable range is wide, various lead-containing materials can be processed, waste of resources is reduced, the energy consumption is low, and it is suitable for large-scale production.

[0011] A method for efficient chemical separation of lead and silver includes the following steps:

[0012] S1. Leaching treatment with an acid solution

[0013] Use an acid solution to leach and treat lead-silver slag, and perform solid-liquid separation to obtain lead-silver enriched slag;

[0014] S2. Extraction treatment with a silver extractant

[0015] Use a silver extractant to extract silver from the lead-silver enriched slag to obtain a silver-containing solution and a lead-containing solid;

[0016] S3. Reduction treatment with a reducing agent

[0017] Add a reducing agent to the silver-containing solution for a reduction reaction. After the reaction ends, perform solid-liquid separation to obtain crude silver, and then obtain silver ingots through high-temperature melting;

[0018] S4. Dissolution treatment with an alkali solution

[0019] Dissolve the lead-containing solid with an alkali solution to obtain a lead-containing solution and lead slag;

[0020] S5. Precipitation treatment with a precipitant or oxidant

[0021] Add a reducing agent to the lead-containing solution to recover silver therein, obtaining a lead-enriched solution and crude silver; add a precipitant or oxidant to the lead-enriched solution to obtain a lead product.

[0022] In some embodiments, in step S1, the lead-silver slag is zinc electrolysis anode slime, steel dust removal ash treatment slag, lead, silver, and copper smelting slag;

[0023] The acid solution is a sulfuric acid solution or a hydrochloric acid solution.

[0024] 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.

[0025] In some embodiments, in step S2, the silver extraction agent is composed of sodium thiosulfate and alkaline thiourea, and the liquid-solid ratio of the silver extraction agent to the lead-silver enriched slag is 2-5:1.

[0026] In some embodiments, in step S2, the reaction temperature is normal temperature, and the pH of the solution system is maintained at 11-14 during the reaction.

[0027] In some embodiments, in step S3, the reducing agent is one or more of formaldehyde, glucose, hydrogen peroxide, sodium sulfite, and sulfur dioxide, the addition amount of the reducing agent is 100-150% of the molar amount of silver ions in the solution, the reduction reaction temperature is 20-70°C, and the reduction reaction time is 0.5-1.5 h.

[0028] In some embodiments, in step S3, the melting temperature of the crude silver is 1000-1200°C.

[0029] In some embodiments, in step S4, the alkali solution is one or more of sodium hydroxide solution, potassium hydroxide solution, ammonium carbonate solution, and sodium carbonate solution, the concentration of the alkali solution is 5-10 mol / L, the liquid-solid ratio is maintained at 5-10:1 during dissolution, the dissolution temperature is 70-90°C, and the dissolution time is 1-5 h.

[0030] In some embodiments, in step S5, the reducing agent used is one or more of glucose, hydrogen peroxide, and formaldehyde, the addition amount of the reducing agent 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.

[0031] In some embodiments, in step S5, the precipitating agent used is one or more of CO2, sodium carbonate, sodium hydroxide, and oxalic acid. The addition amount of the precipitating agent is 100 - 150% of the molar amount of lead ions in the lead-enriched solution, and the precipitation time is 0.5 - 1.5 h. The oxidizing agent is one or more of hydrogen peroxide and chlorine, and the addition amount of the oxidizing agent is 100 - 120% of the molar amount of lead ions in the lead-enriched solution.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The method for efficient chemical separation of lead and silver described in the present application realizes the preliminary separation of lead and silver by leaching soluble metals in lead-silver slag with an acid solution (sulfuric acid or hydrochloric acid); uses a silver extraction agent composed of sodium thiosulfate and alkaline thiourea to extract silver from lead-silver enriched slag; adds a reducing agent (such as formaldehyde, glucose, etc.) to the silver-containing solution to reduce silver ions to silver atoms to form crude silver; uses an alkali solution (such as sodium hydroxide, etc.) to dissolve lead-containing solids to obtain a lead-containing solution; adds a precipitating agent or an oxidizing agent to the lead-enriched solution to obtain a lead product, achieving efficient separation of lead and silver with a separation efficiency of over 90%.

[0034] 2. The method for efficient chemical separation of lead and silver described in the present application is more convenient and easier to control compared with traditional pyrometallurgy. Through the chemical separation and reduction process, the obtained silver ingots and lead products have high purity and high economic value, and are applicable to the recovery and utilization of various lead-containing materials such as electrolytic zinc anode mud, lead-silver smelting slag, and steel-smelting ash slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the drawings and embodiments.

[0036] Figure 1 It is a process flow chart of the method for efficient chemical separation of lead and silver described in the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] For the convenience of those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments does not limit the present invention.

[0038] As used herein, the term "and / or" includes all combinations of any one or more of the associated listed items. The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an", "one" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. Further understanding, when "including" is used in this specification, it specifies the stated features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their combinations.

[0039] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. Further understanding is that terms, such as those defined in a common dictionary, are interpreted to be consistent with their meaning in the context of the relevant field and are not in an idealized or overly formal sense, unless expressly so defined herein.

[0040] The exemplary inventions described herein may suitably lack any one or more element limitations that are not specifically disclosed herein. Accordingly, terms such as "comprising", "including", "containing", etc. shall be understood broadly and non - restrictively. Additionally, the term expressions used herein are used for description without limitation, and it is not intended to use these term expressions that do not include any equivalent characteristics, but only to describe some of their characteristics. However, according to the rights, various modifications are possible within the scope of this invention. Therefore, although this invention has been specifically disclosed through preferred embodiments and optional features, modifications to the inventions disclosed herein to reflect variations may be noted by those skilled in the art, and such modifications and variations will be considered to be within the scope of this invention.

[0041] Term Explanation:

[0042] Lead - silver slag refers to waste or smelting slag containing metals such as lead and silver, and these wastes often contain other metal elements such as copper, zinc, and iron.

[0043] Aiming at the problems that lead and silver are difficult to be efficiently separated and the resource utilization rate is not high in traditional methods, and the energy consumption is large and the pollution is serious in the pyrometallurgical process, this application provides a method for efficient chemical separation of lead and silver, including the following steps:

[0044] S1. Acid solution leaching treatment

[0045] Use acid solution to leach lead - silver slag, perform solid - liquid separation, and obtain lead - silver enriched slag;

[0046] S2. Silver extraction agent extraction treatment

[0047] Use a silver extraction agent to extract silver from the lead - silver enriched slag to obtain a silver - containing solution and lead - containing solid;

[0048] S3. Reducing agent reduction treatment

[0049] Add a reducing agent to the silver - containing solution for reduction reaction. After the reaction ends, perform solid - liquid separation to obtain crude silver, and then obtain silver ingots through high - temperature smelting;

[0050] S4. Alkali solution dissolution treatment

[0051] Use an alkali solution to dissolve the lead - containing solid to obtain a lead - containing solution and lead slag;

[0052] S5. Precipitation treatment with precipitant or oxidant

[0053] Add a reducing agent to the lead-containing solution to recover silver therein, obtaining a lead-enriched solution and crude silver; add a precipitant or oxidant to the lead-enriched solution to obtain a lead product.

[0054] In some embodiments, in step S1, the lead-silver slag is a secondary ore source such as zinc electrolysis anode slime, 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.

[0055] In the present application, the lead-silver slag usually contains various metal elements. Among them, metals such as copper, zinc, and iron have relatively high solubility in acid solutions, while the solubility of lead and silver is relatively low. By selecting an appropriate acid solution (such as sulfuric acid or hydrochloric acid), under suitable concentration, temperature, liquid-solid ratio, and with the addition of 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.

[0056] Specifically, in step S1, use an acid solution to leach the soluble metals (such as copper, zinc, iron, etc.) in the lead-silver slag, while retaining lead and silver in the form of a precipitate in the solid, so that the subsequent steps can more specifically separate lead and silver. This step is the premise and basis for realizing efficient chemical separation of lead and silver.

[0057] Specifically, step S1: Select a sulfuric acid or hydrochloric acid solution with a concentration of 2-5 mol / L as the 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 within a temperature range of 20-70 °C; 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 addition amount of the oxidant is 1%-10%. After the leaching is completed, separate the solid from the solution through equipment such as a centrifuge to obtain a lead-silver enriched slag.

[0058] In some embodiments, in step S2, the silver extraction agent consists of sodium thiosulfate and alkaline thiourea, and the weight ratio of sodium thiosulfate to alkaline thiourea in the silver extraction agent is 1:3; the liquid-solid ratio of the silver extraction 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.

[0059] In this application, in step S2, the lead-silver enriched slag obtained in step S1 is mixed with an appropriate amount of silver extraction agent, and the pH value of the solution system is adjusted as needed; at room temperature, through long-term stirring (24 - 36 hours), the silver extraction agent fully reacts with the silver in the lead-silver enriched slag. During the reaction process, silver gradually transfers from the solid phase to the liquid phase, forming a silver-containing solution. After the reaction is completed, the silver-containing solution is separated from the lead-containing solid through solid-liquid separation techniques (such as filtration, centrifugation, etc.). Through step S2, silver is enriched in the liquid phase, providing conditions for subsequent refining.

[0060] Specifically, the silver extraction agent is a solid, composed of sodium thiosulfate and basic thiourea. The weight ratio of sodium thiosulfate to basic thiourea in the silver extraction agent is 1:3. These two compounds have a strong coordination ability with 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 extraction agent has a high selectivity for silver and is extracted at a pH value between 11 - 14, while having a low reactivity with other metal ions such as lead. This selectivity ensures that the silver extraction agent mainly acts on silver during the extraction process, thereby improving the silver extraction efficiency.

[0061] In some embodiments, in step S3, the reducing agent is one or more of formaldehyde, glucose, hydrogen peroxide, sodium sulfite, sulfur dioxide. The addition amount of the reducing agent 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 - 1.5 h. The melting temperature of the crude silver is 1000 - 1200 °C.

[0062] In this application, in step S3, an appropriate reducing agent is added to the silver-containing solution to reduce the silver ions (Ag + ) in the silver-containing solution to metallic silver (Ag), extract and purify silver from the silver-containing solution, and obtain a crude silver product.

[0063] In some embodiments, in step S4, the alkali solution is one or more of sodium hydroxide solution, potassium hydroxide solution, ammonium carbonate solution, sodium carbonate solution. The concentration of the alkali solution is 5 - 10 mol / L. When dissolving, the liquid-solid ratio is maintained at 5 - 10:1, the dissolution temperature is 70 - 90 °C, and the dissolution time is 1 - 5 h.

[0064] In this application, the lead-containing solid obtained in step S2 is further processed. By dissolving the lead-containing solid with an alkali solution, 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.

[0065] Specifically, the process of step S4 is as follows: Select an appropriate alkaline solution (such as sodium hydroxide solution, potassium hydroxide solution, ammonium carbonate solution, or sodium carbonate solution) and adjust it to the required concentration (usually 5-10 mol / L); Mix the lead-containing solid obtained in step S2 with the alkaline solution in a certain ratio (the liquid-solid ratio is usually 5-10:1), and stir and dissolve at a set temperature (70-90 °C) for a certain period of time (1-5 h). During the dissolution process, lead elements are transferred from the solid to the solution, forming a lead-containing solution;

[0066] After the dissolution is completed, the lead-containing solution is separated from the undissolved lead slag through solid-liquid separation techniques (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 continued dissolution or other treatments; The obtained lead-containing solution enters the next step (such as step S5) for further lead recovery and purification.

[0067] Therefore, in step S4, by dissolving the lead-containing solid with an alkaline solution, lead elements can be efficiently transferred from the solid to the solution, thereby improving the lead recovery rate.

[0068] In some embodiments, in step S5, the reducing agent used is one or more of glucose, hydrogen peroxide, and formaldehyde. The addition amount of the reducing agent 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. The precipitating agent used is one or more of CO2, sodium carbonate, sodium hydroxide, and oxalic acid. The addition amount of the precipitating agent is 100-150% of the molar amount of lead ions in the lead-enriched solution, and the precipitation time is 0.5-1.5 h; The oxidizing agent is one or more of hydrogen peroxide and chlorine. The addition amount of the oxidizing agent is 100-120% of the molar amount of lead ions in the lead-enriched solution.

[0069] In this application, due to the chemical property differences between silver and lead, the silver ions in the lead-containing solution are reduced to metallic silver through a reduction reaction, and at the same time, the lead ions are converted into a precipitable or oxidizable form by using a precipitation reaction or an oxidation reaction, thereby realizing the separation of lead and silver. Specifically, reducing agents such as glucose, hydrogen peroxide, and formaldehyde can selectively reduce silver ions in the solution, while the precipitating agent or oxidizing agent is used to convert lead ions into precipitates or oxides for subsequent treatment and recovery.

[0070] Specifically, the process of step S5 is as follows: an appropriate amount of reducing agent (such as glucose, hydrogen peroxide, formaldehyde, etc.) is added to the lead-containing solution obtained in step S4 to reduce the silver ions in the solution to metallic silver; the addition amount of the reducing agent is usually 100%-150% of the molar amount of silver ions in the solution to ensure that the silver ions are fully reduced. The reduction reaction is carried out at room temperature, and the reaction time is 0.5-1.5 hours. After the reaction is completed, through solid-liquid separation, crude silver and lead-enriched liquid are obtained. The obtained crude silver is returned to step S3 for high-temperature smelting to obtain a silver ingot with higher purity. This step aims to improve the purity of silver products and facilitate subsequent processing and use.

[0071] A precipitating agent (such as CO2, sodium carbonate, sodium hydroxide, oxalic acid, etc.) or an oxidizing agent (such as hydrogen peroxide, chlorine, etc.) is added to the lead-enriched liquid to convert the lead ions into precipitates or oxides; the addition amount of the precipitating agent is usually 100%-150% of the molar amount of lead ions in the lead-enriched liquid 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, through solid-liquid separation, lead products (such as lead carbonate, lead dioxide, etc.) are obtained.

[0072] Therefore, in step S5, through the combination of reduction reaction and precipitation reaction or oxidation reaction, the efficient separation of lead and silver is achieved, and the separation efficiency can reach more than 90%, significantly improving the resource recovery rate. Through solid-liquid separation and high-temperature smelting, the obtained silver ingot and lead products have high purity and high economic value, and can meet the usage requirements of different fields.

[0073] Through the following examples and comparative examples, a method for efficient chemical separation of lead and silver described in this application is further elaborated; Example 1

[0074] The content of the lead-silver slag after the treatment of the dust removal ash in a steel plant sintering workshop is shown in Table 1 below:

[0075] Table 1 Composition of the lead-silver slag after the treatment of the dust removal ash

[0076]

[0077] As shown in Table 1, the acid-soluble metals in the lead-silver slag are mainly copper, iron, and zinc.

[0078] A method for efficient chemical separation of lead and silver includes the following steps:

[0079] The above lead-silver slag is leached with a 2mol / L sulfuric acid solution. During leaching, according to a liquid-solid ratio of 2:1, hydrogen peroxide is added as an oxidizing agent, and the addition amount of hydrogen peroxide is 1%. After stirring at room temperature for 1h, the leaching slurry is put into a centrifuge and centrifuged at a speed of 3000r / min for 5min. The solid after centrifugation is the lead-silver enriched slag, and its composition is shown in Table 2 below.

[0080] Table 2 Composition of lead-silver enriched slag

[0081]

[0082] As shown in Table 2, the silver content is 0.84% (8400 g / t). The silver in the lead-silver enriched slag is leached using a silver leaching agent. After adjusting the pH of the system to 11, leaching is started. During leaching, the liquid-solid ratio is maintained at 2:1, the leaching temperature is room temperature, and the leaching time is 24 h. After leaching is completed, solid-liquid separation is carried out to obtain a silver-containing solution and a lead-containing solid. Glucose is added to the silver-containing solution, and the addition amount of glucose is 100% of the molar amount of silver ions in the solution. Stirring reduction is carried out at 20 °C for 0.5 h. After the reaction is completed, solid-liquid separation is carried out to obtain crude silver. The crude silver is smelted at 1000 °C to obtain silver ingots. The composition of the lead-containing solid is shown in Table 3 below.

[0083] Table 3 Composition of lead-containing solid

[0084]

[0085] As shown in Table 3, the main component of the lead-containing solid is lead sulfate. The lead in the lead-containing solid is dissolved into the solution using a 5 mol / L sodium hydroxide solution. During the dissolution process, the liquid-solid ratio is maintained at 5:1, the dissolution temperature is 70 °C, and the dissolution time is 1 h. After the reaction is completed, solid-liquid separation is carried out 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.

[0086] Table 4 Composition of lead-containing solution

[0087]

[0088] Table 5 Composition of lead slag

[0089]

[0090] As shown in Table 4, glucose is used to reduce the silver ions in the lead-containing solution. The addition amount of glucose is 100% of the molar amount of silver ions in the solution. Stirring reduction is carried out at 20 °C for 0.5 h. After the reaction is completed, solid-liquid separation is carried out to obtain a lead-enriched solution and crude silver. The crude silver is smelted at 1000 °C to obtain silver ingots. The composition of the lead-enriched solution is shown in Table 6 below.

[0091] Table 6 Composition of lead-enriched solution

[0092]

[0093] As shown in Table 6, carbon dioxide was used as a precipitant to prepare lead carbonate precipitate. Carbon dioxide was introduced into the lead-enriched solution, and the mixture was stirred at room temperature for 0.5 h. After the reaction was completed, solid-liquid separation was carried out to obtain lead carbonate product. Hydrogen peroxide can also be added for oxidation. The addition amount of hydrogen peroxide was 100% of the molar amount of lead ions in the lead-enriched solution, and the oxidation time at room temperature was 0.5 h. After the reaction was completed, solid-liquid separation was carried out to obtain lead dioxide product. Example 2

[0094] The content of lead-silver slag after the treatment of dust removal ash in a steel plant sintering workshop is shown in Table 7 below:

[0095] Table 7 Composition of lead-silver slag after dust removal ash treatment

[0096]

[0097] As shown in Table 7, the acid-soluble metals in the lead-silver slag are mainly copper, iron, and zinc.

[0098] A method for efficient chemical separation of lead and silver includes the following steps:

[0099] The above lead-silver slag was leached with 4 mol / L sulfuric acid solution. During leaching, the liquid-solid ratio was 4:1, and hydrogen peroxide was added as an oxidant. The addition amount of hydrogen peroxide was 5%. After stirring at room temperature for 2 h, the leaching slurry was put into a centrifuge and centrifuged at a speed of 3000 r / min for 5 min. The solid after centrifugation was lead-silver enriched slag, and its composition is shown in Table 8 below.

[0100] Table 8 Composition of lead-silver enriched slag

[0101]

[0102] As shown in Table 8, the silver content was 0.71% (7100 g / t). The silver in the lead-silver enriched slag was leached with a silver extractant. After adjusting the pH of the system to 12, leaching was started. During leaching, the liquid-solid ratio was maintained at 4:1, the leaching temperature was room temperature, and the leaching time was 30 h. After the leaching was completed, solid-liquid separation was carried out to obtain a silver-containing solution and a lead-containing solid. Glucose was added to the silver-containing solution. The addition amount of glucose was 120% of the molar amount of silver ions in the solution. After stirring and reducing at 50 °C for 1 h, solid-liquid separation was carried out after the reaction was completed to obtain crude silver. The crude silver was melted at 1100 °C to obtain silver ingots. The composition of the lead-containing solid is shown in Table 9 below.

[0103] Table 9 Composition of lead-containing solid

[0104]

[0105] As shown in Table 9, the main component of the lead-containing solid is lead sulfate. The lead in the lead-containing solid is dissolved into the solution using an 8 mol / L sodium hydroxide solution. During the dissolution process, the liquid-solid ratio is maintained at 8:1, the dissolution temperature is 80 °C, and the dissolution time is 3 h. After the reaction is completed, solid-liquid separation is carried out to obtain a lead-containing solution and lead slag. The composition of the lead-containing solution is shown in Table 9 below.

[0106] Table 10 Composition of the lead-containing solution

[0107]

[0108] As shown in Table 10, glucose is used to reduce the silver ions in the lead-containing solution. The amount of glucose added is 120% of the molar amount of silver ions in the solution. Stirring reduction is carried out at 50 °C for 1 h. After the reaction is completed, solid-liquid separation is carried out to obtain a lead-enriched solution and crude silver. The crude silver is 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.

[0109] Table 11 Composition of the lead-enriched solution

[0110]

[0111] Table 12 Composition of the lead slag

[0112]

[0113] As shown in Table 11, carbon dioxide is used as a precipitant to prepare lead carbonate precipitate. Carbon dioxide is introduced into the lead-enriched solution and stirred at room temperature for 1 h. After the reaction is completed, solid-liquid separation is carried out to obtain lead carbonate products. 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 at room temperature is 1 h. After the reaction is completed, solid-liquid separation is carried out to obtain lead dioxide products. Example 3

[0114] The content of the lead-silver slag after the treatment of the dust removal ash in a steel plant sintering workshop is as shown in Table 13 below:

[0115] Table 13 Composition of the lead-silver slag after the treatment of the dust removal ash

[0116]

[0117] As shown in Table 13, the acid-soluble metals in the lead-silver slag are mainly copper, iron, and zinc;

[0118] A method for efficient chemical separation of lead and silver, comprising the following steps:

[0119] Leach the above lead-silver slag with 5 mol / L sulfuric acid solution. During leaching, according to a liquid-solid ratio of 5:1, add hydrogen peroxide as the oxidant, and the addition amount of hydrogen peroxide is 10%. Stir at room temperature for 3 h, then put the leaching slurry into a centrifuge and centrifuge at a speed of 3000 r / min for 5 min. The solid after centrifugation is the lead-silver enriched slag, and its composition is shown in Table 14 below.

[0120] Table 14 Composition of the lead-silver enriched slag

[0121]

[0122] As shown in Table 14, the silver content is 0.77% (7700 g / t). Use a silver leaching agent to leach the silver from the lead-silver enriched slag. After adjusting the pH of the system to 14, start leaching. During leaching, maintain a liquid-solid ratio of 5:1, the leaching temperature is room temperature, and the leaching time is 36 h. After leaching is completed, perform solid-liquid separation to obtain a silver-containing solution and a lead-containing solid. Add glucose to the silver-containing solution, and the addition amount of glucose is 150% of the molar amount of silver ions in the solution. Stir and reduce at 70 °C for 1.5 h. After the reaction is completed, perform solid-liquid separation to obtain crude silver. The crude silver is melted at 1200 °C to obtain silver ingots. The composition of the lead-containing solid is shown in Table 15 below.

[0123] Table 15 Composition of the lead-containing solid

[0124]

[0125] As shown in Table 15, the main component of the lead-containing solid is lead sulfate. Use 10 mol / L sodium hydroxide solution to dissolve the lead in the lead-containing solid into the solution. During the dissolution process, maintain a liquid-solid ratio of 10:1, the dissolution temperature is 90 °C, and the dissolution time is 5 h. After the reaction is completed, perform solid-liquid separation to obtain a lead-containing solution and lead slag. The composition of the lead-containing solution is shown in Table 16 below.

[0126] Table 16 Composition of the lead-containing solution

[0127]

[0128] As shown in Table 16, use glucose to reduce the silver ions in the lead-containing solution. The addition amount of glucose is 150% of the molar amount of silver ions in the solution. Stir and reduce at 70 °C for 1.5 h. After the reaction is completed, perform solid-liquid separation to obtain a lead-enriched solution and crude silver. The crude silver is melted at 1000 °C to obtain silver ingots. The composition of the lead-enriched solution is shown in Table 17 below. The composition of the lead slag is shown in Table 18 below.

[0129] Table 17 Composition of the lead-enriched solution

[0130]

[0131] Table 18 Composition of the lead slag

[0132]

[0133] As shown in Table 17, carbon dioxide was used as a precipitant to prepare lead carbonate precipitate. Carbon dioxide was introduced into the lead-enriched solution and stirred at room temperature for 1.5 h. After the reaction was completed, solid-liquid separation was carried out to obtain lead carbonate product. Hydrogen peroxide can also be added for oxidation. The addition amount of hydrogen peroxide was 120% of the molar amount of lead ions in the lead-enriched solution, and the oxidation time at room temperature was 1.5 h. After the reaction was completed, solid-liquid separation was carried out to obtain lead dioxide product.

[0134] The purity of the silver ingots and lead dioxide products obtained in Examples 1-3 was detected, and the detection results are shown in Table 19 below.

[0135] Table 19 Detection Results of Examples 1-3

[0136]

[0137] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious substitution 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 Adding a reducing agent to the lead-containing solution to recover the silver therein to obtain a lead-enriched solution and crude silver; adding a precipitant or an oxidant to the lead-enriched solution to obtain a lead product; Wherein, 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; In step S1, an oxidant is also added, wherein the oxidant is one or more of hydrogen peroxide, chlorine, sodium hypochlorite, calcium hypochlorite, and chlorine dioxide; 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; the reaction temperature is room temperature, and the pH of the solution system is maintained at 11-14 during the reaction; 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.

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

3. 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.

4. 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.

5. 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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