Method for efficient recovery of metals from sintering machine head ash leach solution

Abstract

The present application relates to the technical field of metal resource recycling, in particular to a method for efficient recycling of metals in sintering machine head ash leaching solution. The present application provides a method for efficient recycling of metals in sintering machine head ash leaching solution, using a specific concentration of first acid solution to leach sintering machine head ash at a certain temperature, so that the valuable metals in it are dissolved into the leaching solution; then use the first displacer to enrich these metals from the solution to form a displacement solid, and further separate silver, bismuth, copper and other metals through subsequent acid dissolution process; for silver-containing solid, fourth acid solution is used for dissolution and a reducing agent is added to obtain sponge silver, and gold-containing solid is dissolved with aqua regia and then reduced to sponge gold again, and finally smelted into silver ingot and gold ingot respectively. The method described in the present application solves the problems of high energy consumption, high cost, secondary pollution and poor recovery effect of precious metals and other valuable metals in the traditional treatment process.

Description

Technical Field

[0001] This invention relates to the technical field of metal resource recycling, and in particular to a method for the efficient recycling of metals from sintering machine head ash leachate. Background Technology

[0002] The steel industry is a vital pillar of the national economy, but its production process generates a large amount of dust, collectively known as dust collector ash. Sintering machine head ash is a typical example of dust collector ash in the steel industry, characterized by its large output, small particle size, and high content of harmful elements such as K, Na, Ca, Zn, and Cl, posing a significant threat to the environment. In recent years, with increasing environmental awareness and the growing demand for resource recycling, the resource utilization technology of sintering machine head ash has received widespread attention and rapid development.

[0003] Currently, there are several main technical approaches for treating sintering machine head ash:

[0004] Pyrometallurgical treatment: This method uses high-temperature sintering or melting to fix or volatilize harmful elements in the ash from the sintering machine head, achieving resource recovery and utilization. However, pyrometallurgical treatment is energy-intensive, requires large equipment investments, and is prone to generating secondary pollution, making it difficult to meet modern environmental protection requirements.

[0005] Combined pyrometallurgical-hydrometallurgical process: This process combines the advantages of pyrometallurgical and hydrometallurgical methods, achieving efficient resource recovery through pretreatment and subsequent chemical treatment. While this combined process overcomes the limitations of single technologies to some extent, it is complex and incurs high investment and operating costs.

[0006] Chemical precipitation method: This method involves leaching sintering machine head ash with water, then adding sodium sulfide to the leachate to remove calcium and heavy metals, thus removing impurity ions and obtaining a purified solution. While some potassium and sodium salts can be recovered, the recovery effect on precious metals and other valuable metals is poor, resulting in significant resource waste. Furthermore, the generated precipitates require further treatment, which can easily cause secondary pollution.

[0007] Therefore, this application provides a method for the efficient recovery and utilization of metals from the leachate of sintering machine head ash. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, this invention provides a method for the efficient recovery and utilization of metals from sintering machine head ash leachate. The method involves leaching the sintering machine head ash with a first acid solution of a specific concentration at a certain temperature, dissolving valuable metals into the leachate. Then, a first displacement agent is used to enrich these metals from the solution, forming displacement solids. Subsequent acid dissolution processes further separate metals such as silver, bismuth, and copper. For silver-containing solids, a fourth acid solution is used for dissolution, and a reducing agent is added to obtain sponge silver. Gold-containing solids are dissolved in aqua regia and then reduced again to sponge gold, which is finally smelted into silver ingots and gold ingots, respectively. The method described in this application solves the problems of high energy consumption, high cost, secondary pollution, and poor recovery efficiency of precious metals and other valuable metals in traditional processing methods.

[0009] When this application solves its technical problem, the technical solution adopted is:

[0010] A method for efficient recovery and utilization of metals from sintering machine head ash leachate includes the following steps:

[0011] S1. The sintering machine head ash is treated by leaching with the first acid solution. An oxidant is added during the leaching process. After solid-liquid separation, leachate and leachate solid are obtained. The leachate solid is rinsed and returned to the sintering batch for use.

[0012] S2. Add the first displacement agent to the leachate obtained in step S1 to perform displacement, and separate the solid and liquid to obtain the first displacement liquid and the displacement solid;

[0013] An oxidant is added to the first displacement solution, followed by a first precipitant to adjust the pH of the first displacement solution to 5-6. After stirring for 0.5-1.5 hours, solid-liquid separation is performed to obtain a first impurity-removed solution and a first impurity-removed solid. A second displacement agent is added to the first displacement solution for displacement. After solid-liquid separation, crude lead and a second displacement solution are obtained. The first precipitant is added to the second displacement solution to adjust the pH of the second displacement solution to 11-13. After solid-liquid separation, a weight-removed solution and a weight-removed solid are obtained.

[0014] S3. Add a decontamination agent to the deweighted liquid obtained in step S2 for decontamination treatment. After solid-liquid separation, a second decontamination liquid and a second decontamination solid are obtained.

[0015] The second impurity-removed liquid is evaporated to obtain potassium and sodium salts;

[0016] The first and second impurity-removed solids are returned to the sintering batch for use.

[0017] S4. Dissolve the displacement solid obtained in step S2 using the first acid solution to obtain a second acid solution and a second acid-dissolved solid.

[0018] The second acid-soluble solid is dissolved in a third acid solution, and an oxidizing agent is added during the acid dissolution process to obtain a silver-containing solid and a bismuth-containing solution. The bismuth-containing solution is added to a second precipitating agent, and after solid-liquid separation, bismuth oxychloride and a copper-containing solution are obtained. The copper-containing solution is mixed with the second acid solution and a third displacement agent is added to obtain crude copper.

[0019] S5. Dissolve the silver-containing solid obtained in step S4 using a fourth acid solution to obtain a silver-containing solution and a gold-containing solid; add a first reducing agent to the silver-containing solution to obtain sponge silver, and then smelt it to obtain a silver ingot; dissolve the gold-containing solid using aqua regia to obtain a gold-containing liquid, add a second reducing agent to the gold-containing liquid to obtain sponge gold, and then smelt it to obtain a gold ingot.

[0020] In one or more technical solutions, in step S1, the first acid solution is hydrochloric acid; the concentration of hydrochloric acid is 1-3 mol / L.

[0021] In one or more technical solutions, in step S1, the leaching temperature is 60-90℃, the leaching time is 7-9h, and the leaching liquid-solid ratio is 2-5:1.

[0022] In one or more technical solutions, in step S2, the first displacing agent is any one or more of copper powder, iron powder, lead powder, and zinc powder, the dosage of the first displacing agent is 5-25 g / L, the displacing temperature is 50-70℃, and the displacing time is 1-3 h.

[0023] In one or more technical solutions, in step S2, the oxidant is any one or more of chlorine, hydrogen peroxide, calcium hypochlorite, sodium hypochlorite, and chlorine dioxide.

[0024] In one or more technical solutions, in step S2, the first precipitant is any one or more of lime slurry, calcium oxide, sodium hydroxide, and carbon dioxide.

[0025] In one or more technical solutions, in step S3, the impurity removal agent is any one or more of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

[0026] In one or more technical solutions, in step S4, when the first acid solution is dissolved, the liquid-to-solid ratio is maintained at 5-9:1, the dissolution temperature is 50-80℃, and the dissolution time is 2-4h.

[0027] The third acid solution is a hydrochloric acid solution or a sulfuric acid solution, and the concentration of the third acid solution is 1-5 mol / L. When dissolving the third acid solution, the liquid-solid ratio is maintained at 5-9:1 and the dissolution temperature is 50-80℃. The oxidant is any one or more of chlorine, hydrogen peroxide, calcium hypochlorite, sodium hypochlorite, and chlorine dioxide. The second precipitant is any one of quicklime and sodium hydroxide. The third displacement agent is any one or more of iron powder, lead powder, and zinc powder.

[0028] In one or more technical solutions, in step S5, the fourth acid solution is a nitric acid solution, the concentration of the fourth acid solution is 1-5 mol / L, the first reducing agent is any one or more of sodium sulfite, glucose, glycine, and hydrazine hydrate, and the ratio of the molar amount of the first reducing agent to the molar amount of silver ions in the silver-containing solution is 1-3:1.

[0029] In one or more technical solutions, in step S5, the second reducing agent is any one or more of sodium sulfite, sodium bisulfite, oxalic acid, formic acid, and hydrazine hydrate, and the ratio of the molar amount of the second reducing agent to the molar amount of gold ions in the gold-containing liquid is 1-4:1.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The method described in this invention uses a displacement agent to enrich the valuable metals in the leaching liquid of sintering machine head ash, and then uses acid to dissolve and recover the precious metals stepwise. The resulting metal product has high purity, good separation and recovery effect, and the residual liquid generated after separation can be returned to the system for continued use without generating secondary pollution. It has strong applicability, high economic benefits, and is suitable for large-scale production. Detailed Implementation

[0032] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0033] As used herein, “and / or” includes all combinations of any one or more of the associated listed items. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the 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. Further understanding is needed; when used in this specification, “comprising” designates 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 combinations thereof.

[0034] 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 art to which this invention pertains. Further understanding is that terms, such as those defined in common dictionaries, are interpreted in accordance with their meaning in the context of the relevant field and are not idealized or overly formal, unless expressly defined herein.

[0035] The exemplary invention described herein may suitably omit any one or more limiting elements, which are not specifically disclosed herein. Therefore, terms such as “comprising,” “including,” “containing,” etc., should be interpreted broadly and non-limitingly. Furthermore, the terminology used herein is for descriptive purposes without limitation, and it is unintentional to use terms that do not include any equivalent characteristics, but only to describe a portion of their characteristics; however, various modifications are possible within the scope of the invention according to the claims. Therefore, while the invention has been specifically disclosed through preferred embodiments and optional features, variations of the invention embodied by the modifications disclosed herein may be noted by those skilled in the art, and such modifications and variations are considered to be within the scope of the invention.

[0036] Terminology Explanation:

[0037] The second purified solution is the solution obtained after step S3.

[0038] The solution after removing heavy metals is the solution treated with pH 11-13 in step S2.

[0039] The first displacement agent (iron powder, zinc powder, etc.) utilizes the difference in metal activity to replace precious metals (such as Ag, Au), making full use of the characteristics of the first displacement agent having strong reducing properties and low cost, and can preferentially replace precious metal ions such as silver and gold.

[0040] The second displacement agent is used to displace heavy metals (such as lead, thallium, and cadmium).

[0041] A method for efficient recovery and utilization of metals from sintering machine head ash leachate includes the following steps:

[0042] S1. The sintering machine head ash is treated by leaching with the first acid solution. An oxidant is added during the leaching process. After solid-liquid separation, leachate and leachate solid are obtained. The leachate solid is rinsed and returned to the sintering batch for use.

[0043] S2. Add the first displacement agent to the leachate obtained in step S1 to perform displacement, and separate the solid and liquid to obtain the first displacement liquid and the displacement solid;

[0044] An oxidant is added to the first displacement solution, followed by a first precipitant to adjust the pH of the first displacement solution to 5-6. After stirring for 0.5-1.5 hours, solid-liquid separation is performed to obtain a first impurity-removed solution and a first impurity-removed solid. A second displacement agent is added to the first displacement solution for displacement. After solid-liquid separation, crude lead and a second displacement solution are obtained. The first precipitant is added to the second displacement solution to adjust the pH of the second displacement solution to 11-13. After solid-liquid separation, a weight-removed solution and a weight-removed solid are obtained.

[0045] S3. Add a decontamination agent to the deweighted liquid obtained in step S2 for decontamination treatment. After solid-liquid separation, a second decontamination liquid and a second decontamination solid are obtained.

[0046] The second impurity-removed liquid is evaporated to obtain potassium and sodium salts;

[0047] The first and second impurity-removed solids are returned to the sintering batch for use.

[0048] S4. Dissolve the displacement solid obtained in step S2 using the first acid solution to obtain a second acid solution and a second acid-dissolved solid.

[0049] The second acid-soluble solid is dissolved in a third acid solution, and an oxidizing agent is added during the acid dissolution process to obtain a silver-containing solid and a bismuth-containing solution. The bismuth-containing solution is added to a second precipitating agent, and after solid-liquid separation, bismuth oxychloride and a copper-containing solution are obtained. The copper-containing solution is mixed with the second acid solution and a third displacement agent is added to obtain crude copper.

[0050] S5. Dissolve the silver-containing solid obtained in step S4 using a fourth acid solution to obtain a silver-containing solution and a gold-containing solid; add a first reducing agent to the silver-containing solution to obtain sponge silver, and then smelt it to obtain a silver ingot; dissolve the gold-containing solid using aqua regia to obtain a gold-containing liquid, add a second reducing agent to the gold-containing liquid to obtain sponge gold, and then smelt it to obtain a gold ingot.

[0051] Specifically, in step S1, the first acid solution is hydrochloric acid; the concentration of hydrochloric acid is 1-3 mol / L. The leaching temperature is 60-90℃, the leaching time is 7-9 hours, and the leaching liquid-to-solid ratio is 2-5:1.

[0052] Specifically, the oxidant is any one of chlorine, hydrogen peroxide, calcium hypochlorite, sodium hypochlorite, or chlorine dioxide.

[0053] More specifically, in step S1, the oxidant and the acid (such as HCl) work together to form a strongly oxidizing environment, which can powerfully decompose the mineral structure encapsulating the metal and release metal ions.

[0054] Specifically, in step S2, the first displacing agent is any one or more of copper powder, iron powder, lead powder, and zinc powder, with a dosage of 5-25 g / L, a displacing temperature of 50-70℃, and a displacing time of 1-3 h. The oxidizing agent is any one or more of chlorine, hydrogen peroxide, calcium hypochlorite, sodium hypochlorite, and chlorine dioxide, with a feed mass of 0.5%-5% of the mass of the liquid after the first displacing. The second displacing agent is any one or more of zinc powder, zinc wire, aluminum powder, and aluminum sheet, with a dosage of 1-5 g / L, a displacing temperature of room temperature, and a displacing time of 0.5-1.5 h. The first precipitant is any one or more of lime slurry, calcium oxide, sodium hydroxide, and carbon dioxide.

[0055] In this application, copper powder, iron powder, lead powder, and zinc powder are used as the first displacing agent to utilize the reducing properties of these metals to displace less reactive metals (such as silver and bismuth) in the leaching solution. The dosage of the first displacing agent is set to 5-25 g / L, which ensures sufficient reactivity for efficient displacement without causing waste or introducing unnecessary impurities due to excessive dosage.

[0056] Oxidizing agents (chlorine, hydrogen peroxide, calcium hypochlorite, sodium hypochlorite, chlorine dioxide) are used to maintain the oxidizing environment of the solution, helping to prevent certain metal ions from being reduced to elemental or lower valence states, thus affecting recovery efficiency. The feed mass of the oxidizing agent is 0.5%-5% of the mass of the liquid after the first displacement; this range is designed to provide the necessary oxidizing capacity while minimizing environmental impact.

[0057] Lime slurry, calcium oxide, sodium hydroxide, carbon dioxide, etc. are used as the first precipitant to adjust the pH of the solution to alkaline (pH=11-13), so that some unwanted heavy metal ions form insoluble hydroxides and precipitate, which facilitates subsequent separation operations.

[0058] Zinc powder, zinc wire, aluminum powder, and aluminum sheet were selected as the second displacement agent, with a dosage set at 1-5 g / L. The purpose was to utilize the reducing properties of these metals to further enrich or separate specific metals in the solution.

[0059] Specifically, in step S3, the impurity removal agent is any one or more of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide. The molar amount of the impurity removal agent added is 100-120% of the molar amount of calcium ions measured in the liquid after weight removal. The impurity removal time is 0.5-1.5 hours, and the impurity removal temperature is room temperature.

[0060] In this application, sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide are used as impurity removers to utilize their properties to react with certain impurity ions (such as Ca2+) in the solution. 2+ Mg 2+The reaction produces insoluble precipitates, which can be removed from the solution by solid-liquid separation.

[0061] Specifically, in step S4, when the first acid solution is dissolved, the liquid-to-solid ratio is maintained at 5-9:1, the dissolution temperature is 50-80℃, and the dissolution time is 2-4 hours.

[0062] The third acid solution is a hydrochloric acid solution or a sulfuric acid solution, and the concentration of the third acid solution is 1-5 mol / L. When dissolving the third acid solution, the liquid-solid ratio is maintained at 5-9:1 and the dissolution temperature is 50-80℃. The oxidant is any one or more of chlorine, hydrogen peroxide, calcium hypochlorite, sodium hypochlorite, and chlorine dioxide. The second precipitant is any one or more of quicklime, sodium hydroxide, and potassium hydroxide. The third displacement agent is any one or more of iron powder, lead powder, and zinc powder, and the dosage of the third displacement agent is 5-15 g / L.

[0063] In this application, hydrochloric acid is selected as the first acid solution, and the concentration of hydrochloric acid is set to 1-3 mol / L. The purpose is to dissolve and replace small amounts of iron, iron oxide and copper oxide in the solid, without dissolving precious metals such as gold and silver, so as to avoid the consumption of precious metals (silver and gold) by excessive acid.

[0064] Hydrochloric acid or sulfuric acid is used as the third acid solution, with a concentration of 1-5 mol / L. An oxidant is added, mainly to dissolve the elemental copper and bismuth in the second acid-soluble solid, so that the bismuth element can be recovered later.

[0065] Quicklime and sodium hydroxide are used as the second precipitant to adjust the pH value to 2-3, thereby forming bismuth oxychloride, a poorly soluble form of bismuth. This allows the target metal ions (such as bismuth ions) to form a poorly soluble precipitate, facilitating subsequent solid-liquid separation.

[0066] In this application, quicklime, sodium hydroxide, etc. are added to the bismuth-containing solution to adjust the pH to 2-3, so that the bismuth ions are hydrolyzed to generate bismuth oxychloride. After solid-liquid separation, bismuth oxychloride and copper-containing solution are obtained. The copper-containing solution is mixed with the second acid solution and a third displacement agent is added to obtain crude copper.

[0067] Specifically, in step S5, the fourth acid solution is a nitric acid solution with a concentration of 1-5 mol / L. The first reducing agent is any one or more of sodium sulfite, glucose, glycine, and hydrazine hydrate. The molar ratio of the first reducing agent to the molar ratio of silver ions in the silver-containing solution is 1-3:1. After smelting at 1000-1200℃, silver ingots are obtained.

[0068] The second reducing agent is any one or more of sodium sulfite, sodium bisulfite, oxalic acid, formic acid, and hydrazine hydrate. The molar ratio of the second reducing agent to the molar ratio of gold ions in the gold-containing liquid is 1-4:1. After smelting at 1100-1300℃, gold ingots are obtained.

[0069] In this application, nitric acid was chosen as the fourth acid solution with a concentration of 1-5 mol / L in order to create a suitable acidic environment to maximize the dissolution of silver and other metal components in the silver-containing solid.

[0070] Sodium sulfite, glucose, glycine, and hydrazine hydrate were selected as the primary reducing agents, and the molar ratio of their dosage to the molar ratio of silver ions in the silver-containing solution was set at 1-3:1. These reducing agents can effectively reduce silver ions to elemental silver (sponge silver), and the appropriate molar ratio ensures that almost all silver ions are reduced, while avoiding the excessive introduction of unnecessary impurities.

[0071] For gold-containing liquids, sodium sulfite, sodium bisulfite, oxalic acid, formic acid, and hydrazine hydrate were selected as secondary reducing agents, with the molar ratio of their dosage to the molar amount of gold ions in the liquid set at 1-4:1. The reduction process of gold is relatively complex and requires stronger reducing power; therefore, several potentially more effective reducing agents were selected, and the ratio of reducing agent to gold ions was appropriately increased to ensure that the gold ions were fully reduced to elemental gold (sponge gold).

[0072] The method described in this application will be further illustrated by the following examples and comparative examples: the elemental content detection adopts inductively coupled plasma optical emission spectrometry (ICP-OES).

[0073] Example 1: A method for efficient recovery and utilization of metals from sintering machine head ash leachate, comprising the following steps:

[0074] (1) Take 100 kg of sintering machine head ash, add 1 mol / L hydrochloric acid solution at a liquid-to-solid ratio of 2:1, leach at 60℃ for 7 h, and after the reaction is complete, perform liquid-solid separation to obtain leachate and leachate solid. The leachate is used for the next process, and the leachate solid is rinsed with clean water and returned to the sintering batch. The elemental composition of the leachate is shown in Table 1 below.

[0075] Table 1. Elemental composition of leachate

[0076]

[0077] (2) As shown in Table 1 above, iron powder was added to the leachate for replacement to enrich the valuable metals in the leachate. The amount of replacement agent was 5 g / L. The replacement temperature was kept at 50℃ and the replacement time was 1 h. After the replacement was completed, solid-liquid separation was performed to obtain the first replacement liquid and the replacement solid. The composition of the replacement liquid is shown in Table 2 below.

[0078] Table 2. Elemental composition of the solution after displacement

[0079]

[0080] (3) Add hydrogen peroxide to the first displacement liquid. The amount of hydrogen peroxide added (compared to the weight of the displacement liquid) is 0.5%. Then add calcium oxide and adjust the pH of the solution to 5. After stirring and reacting for 0.5 h, perform solid-liquid separation to obtain the first impurity-removed solid and the first impurity-removed liquid. Add zinc powder to the first impurity-removed liquid for displacement. The amount of zinc powder is 1 g / L. After stirring and reacting at room temperature for 0.5 h, perform solid-liquid separation to obtain crude lead and the second displacement liquid. Add calcium oxide to the second displacement liquid and adjust the pH of the solution to 11. After the reaction is completed, perform solid-liquid separation to obtain the weight-removed solid and the weight-removed liquid. Add sodium carbonate as an impurity remover to the weight-removed liquid. The molar amount of the impurity remover added is 100% of the molar amount of calcium ions measured in the weight-removed liquid. After reacting for 0.5 h, perform solid-liquid separation to obtain the second impurity-removed liquid and the second impurity-removed solid. The composition of the second impurity-removed liquid is shown in Table 3 below. The second impurity-removed liquid enters the evaporation crystallization system to obtain potassium and sodium salts. The first and second impurity-removed solids can be returned to the sintering feed.

[0081] Table 3. Elemental composition of the liquid after the second impurity removal

[0082]

[0083] (4) The components of the replaced solids in step (2) are shown in Table 4 below:

[0084] Table 4. Elemental composition of the replaced solid

[0085]

[0086] The above-mentioned displacement solid was dissolved using a 1 mol / L hydrochloric acid solution. The liquid-to-solid ratio was maintained at 5:1, and the dissolution temperature was 50°C. After 2 hours of reaction, solid-liquid separation was performed to obtain an acid solution and an acid-soluble solid. The acid-soluble solid was then dissolved a second time using a 1 mol / L hydrochloric acid solution, maintaining a liquid-to-solid ratio of 5:1, a dissolution temperature of 50°C, and a dissolution time of 2 hours. Hydrogen peroxide was added during the dissolution process at a concentration of 1%. After the reaction was complete, a silver-containing solid and a bismuth-containing solution were obtained. The silver-containing solid is shown in Table 5 below.

[0087] Table 5. Elemental composition of silver-containing solids

[0088]

[0089] (5) Add quicklime to the bismuth-containing solution to adjust the pH of the solution to 2. After the reaction is completed, solid-liquid separation is obtained to get bismuth oxychloride and copper-containing solution. After the copper-containing solution is mixed with the acid solution, iron powder is added for replacement. The amount of iron powder added is 5g / L. After the reaction is completed, solid-liquid separation is obtained to get crude copper.

[0090] (6) The silver-containing solid was dissolved in 1 mol / L nitric acid solution. After solid-liquid separation, a silver-containing solution and a gold-containing solid were obtained. Glucose was added to the silver-containing solution, with the molar ratio of glucose to silver ions in the solution being 1:1. After reduction, sponge silver was obtained, which was then smelted at 1000℃ to obtain a silver ingot (1.75 g). The gold-containing solid was dissolved in aqua regia, and a gold-containing liquid was obtained. Sodium sulfite was added to the gold-containing liquid, with the molar ratio of sodium sulfite to gold ions in the solution being 1:1. After reduction, sponge gold was obtained, which was then smelted at 1100℃ to obtain a gold ingot (0.49 g).

[0091] Example 2: A method for efficient recovery and utilization of metals from sintering machine head ash leachate, comprising the following steps:

[0092] (1) Take 100 kg of sintering machine head ash, add 2 mol / L hydrochloric acid solution at a liquid-to-solid ratio of 4:1, leach at 70℃ for 8 h, and after the reaction is complete, perform liquid-solid separation to obtain leachate and leachate solid. The leachate is used for the next process, and the leachate solid is rinsed with clean water and returned to the sintering batch. The elemental composition of the leachate is shown in Table 6 below.

[0093] Table 6. Elemental composition of leachate

[0094]

[0095] (2) As shown in Table 6 above, iron powder was added to the leachate for replacement to enrich the valuable metals in the leachate. The amount of replacement agent was 15 g / L. The replacement temperature was kept at 60℃ and the replacement time was 2 h. After the replacement was completed, solid-liquid separation was performed to obtain the first replacement liquid and the replacement solid. The composition of the replacement liquid is shown in Table 7 below.

[0096] Table 7. Elemental composition of the solution after the first displacement.

[0097]

[0098] (3) Add hydrogen peroxide to the first displacement liquid at a concentration of 2.5%, then add calcium oxide to adjust the pH of the solution to 5. After stirring for 1 hour, perform solid-liquid separation to obtain the first impurity-removed solid and the first impurity-removed liquid. Add zinc powder to the first impurity-removed liquid for displacement at a concentration of 2.5 g / L. After stirring for 1 hour at room temperature, perform solid-liquid separation to obtain crude lead and the second displacement liquid. Add calcium oxide to the second displacement liquid to adjust the pH of the solution to 12. After the reaction is complete, perform solid-liquid separation to obtain the weight-removed solid and the weight-removed liquid. Add sodium carbonate as a removal agent to the weight-removed liquid at a molar amount that is 110% of the molar amount of calcium ions measured in the weight-removed liquid. After reacting for 1 hour, perform solid-liquid separation to obtain the second impurity-removed liquid and the second impurity-removed solid. The composition of the second impurity-removed liquid is shown in Table 8 below. The second impurity-removed liquid enters the evaporation crystallization system to obtain potassium and sodium salts. The first and second impurity-removed solids can be returned to the sintering feed.

[0099] Table 8. Elemental composition of the liquid after the second impurity removal process.

[0100]

[0101] (4) The components of the replaced solids in step (2) are shown in Table 9 below:

[0102] Table 9. Composition of elements in the replaced solid.

[0103]

[0104] The above-mentioned displacement solid was dissolved using hydrochloric acid solution. A 2 mol / L hydrochloric acid solution was added, maintaining a liquid-to-solid ratio of 7:1 during dissolution at 60°C. After 3 hours of reaction, solid-liquid separation was performed to obtain an acidic solution and an acid-soluble solid. The acid-soluble solid was then dissolved a second time using a 3 mol / L hydrochloric acid solution, maintaining a liquid-to-solid ratio of 7:1 at 60°C for 3 hours. Hydrogen peroxide (5%) was added during the dissolution process. After the reaction was complete, a silver-containing solid and a bismuth-containing solution were obtained. The silver-containing solid is shown in Table 10 below.

[0105] Table 10 Elemental composition of silver-containing solids

[0106]

[0107] (5) Add sodium hydroxide to the bismuth-containing solution to adjust the pH of the solution to 2.5. After the reaction is completed, solid-liquid separation is performed to obtain bismuth oxychloride and copper-containing solution. After the copper-containing solution is mixed with the acid solution, iron powder is added for replacement. The amount of iron powder added is 10 g / L. After the reaction is completed, solid-liquid separation is performed to obtain crude copper.

[0108] (6) The silver-containing solid was dissolved in 3 mol / L nitric acid solution. After solid-liquid separation, a silver-containing solution and a gold-containing solid were obtained. Glucose was added to the silver-containing solution, with the molar ratio of glucose to silver ions in the solution being 2:1. After reduction, sponge silver was obtained, which was then smelted at 1100℃ to obtain a silver ingot (1.81 g). The gold-containing solid was dissolved in aqua regia, and after dissolution, a gold-containing liquid was obtained. Sodium sulfite was added to the gold-containing liquid, with the molar ratio of sodium sulfite to gold ions in the solution being 3:1. After reduction, sponge gold was obtained, which was then smelted at 1200℃ to obtain a gold ingot (0.54 g).

[0109] Example 3: A method for efficient recovery and utilization of metals from sintering machine head ash leachate, comprising the following steps:

[0110] (1) Take 100 kg of sintering machine head ash, add 3 mol / L hydrochloric acid solution at a liquid-to-solid ratio of 5:1, leach at 90℃ for 9 h, and after the reaction is complete, perform liquid-solid separation to obtain leachate and leachate solid. The leachate is used for the next process, and the leachate solid is rinsed with clean water and returned to the sintering batch. The elemental composition of the leachate is shown in Table 11 below.

[0111] Table 11 Elemental composition of leachate

[0112]

[0113] (2) As shown in Table 11 above, iron powder was added to the leachate for replacement to enrich the valuable metals in the leachate. The amount of replacement agent was 25 g / L. The replacement temperature was maintained at 70℃ and the replacement time was 3 h. After the replacement was completed, solid-liquid separation was performed to obtain the first replacement liquid and the replacement solid. The composition of the first replacement liquid is shown in Table 12 below.

[0114] Table 12 Elemental composition of the solution after the first displacement

[0115]

[0116] (3) Add hydrogen peroxide to the first displacement liquid at a concentration of 5%, then add calcium oxide to adjust the pH of the solution to 6. After stirring for 1.5 h, perform solid-liquid separation to obtain the first impurity-removed solid and the first impurity-removed liquid. Add zinc powder to the first impurity-removed liquid for displacement at a concentration of 5 g / L. After stirring for 1.5 h at room temperature, perform solid-liquid separation to obtain crude lead and the second displacement liquid. Add calcium oxide to the second displacement liquid to adjust the pH of the solution to 13. After the reaction is complete, perform solid-liquid separation to obtain the weight-removed solid and the weight-removed liquid. Add sodium carbonate as a removal agent to the weight-removed liquid. The molar amount of the removal agent is 120% of the molar amount of calcium ions measured in the weight-removed liquid. After reacting for 1.5 h, perform solid-liquid separation to obtain the second impurity-removed liquid and the second impurity-removed solid. The composition of the second impurity-removed liquid is shown in Table 13 below. The second impurity-removed liquid enters the evaporation crystallization system to obtain potassium and sodium salts. The first and second impurity-removed solids can be returned to the sintering feed.

[0117] Table 13 Elemental composition of the second impurity removal solution

[0118]

[0119] (4) The components of the replaced solids in step (2) are shown in Table 14 below:

[0120] Table 14 Composition of elements in the replaced solid

[0121]

[0122] The above-mentioned displacement solid was dissolved using hydrochloric acid solution. A 3 mol / L hydrochloric acid solution was added, maintaining a liquid-to-solid ratio of 9:1 at 80°C. After reacting for 4 hours, solid-liquid separation was performed to obtain an acidic solution and an acid-soluble solid. Then, the acid-soluble solid was dissolved a second time using a 5 mol / L hydrochloric acid solution, maintaining a liquid-to-solid ratio of 9:1 at 80°C for 4 hours. Hydrogen peroxide was added during the dissolution process (10% of the solution). After the reaction was complete, a silver-containing solid and a bismuth-containing solution were obtained. The silver-containing solid is shown in Table 15 below.

[0123] Table 15 Elemental composition of silver-containing solids

[0124]

[0125] (5) Add quicklime to the bismuth-containing solution to adjust the pH of the solution to 3. After the reaction is completed, solid-liquid separation is obtained to get bismuth oxychloride and copper-containing solution. After the copper-containing solution is mixed with the acid solution, iron powder is added for replacement. The amount of iron powder added is 15g / L. After the reaction is completed, solid-liquid separation is obtained to get crude copper.

[0126] (6) The silver-containing solid was dissolved in 5 mol / L nitric acid solution. After solid-liquid separation, a silver-containing solution and a gold-containing solid were obtained. Glucose was added to the silver-containing solution, with the molar ratio of glucose to silver ions in the solution being 3:1. After reduction, sponge silver was obtained, which was then smelted at 1200℃ to obtain a silver ingot (1.86 g). The gold-containing solid was dissolved in aqua regia, and after dissolution, a gold-containing liquid was obtained. Sodium sulfite was added to the gold-containing liquid, with the molar ratio of sodium sulfite to gold ions in the solution being 4:1. After reduction, sponge gold was obtained, which was then smelted at 1300℃ to obtain a gold ingot (0.56 g).

[0127] Comparative Example 1

[0128] In step S1, 1 mol / L hydrochloric acid is used to leach the sintering machine head ash without adding an oxidant (such as hydrogen peroxide).

[0129] The other steps are the same as in Example 1.

[0130] Comparative Example 2

[0131] In step S1, 1 mol / L sulfuric acid (H2SO4) is used instead of hydrochloric acid (HCl), and other parameters (temperature, time) are the same as in Example 1; other steps are consistent with Example 1.

[0132] Comparative Example 3

[0133] In step S2, only iron powder is used (without using zinc powder to replace Pb in steps), directly replacing all metals; the other steps are the same as in Example 1.

[0134] Comparative Example 4

[0135] In step S2, no displacement is performed; Ca(OH)2 is directly added to the leachate to adjust the pH to 11-13 to precipitate heavy metals; the other steps are the same as in Example 1.

[0136] The silver ingot production and gold ingot production obtained from Example 1 and Comparative Examples 1-4 are summarized in Table 16 below.

[0137] Table 16 Summary of Silver Ingot Production and Gold Ingot Production

[0138]

[0139] As shown in Table 16, Example 1 uses hydrogen peroxide in conjunction with HCl to create a strong oxidizing environment, which significantly improves the metal leaching rate (e.g., Ag leaching rate is increased by about 90%); the silver and gold yields are 1.9 times and 2.3 times that of Comparative Example 1, respectively, and other metals (Pb, Bi, Cu) are recovered more thoroughly.

[0140] HCl has better selective dissolution of precious metals, while H2SO4 generates sulfate precipitates (such as CaSO4), which hinders the displacement reaction; the silver and gold yields in Comparative Example 2 are only 39% and 31% of those in Example 1, and the risk of secondary pollution is high (sulfate waste needs to be treated).

[0141] Example 1 uses iron powder to preferentially replace Ag / Au, followed by zinc powder to replace Pb, thus avoiding co-replacement. In Comparative Example 3, the lack of stepwise replacement led to the co-precipitation of Pb and Ag / Au, reducing purity. The silver and gold yields in Comparative Example 3 were 64% and 63% of those in Example 1, respectively, and the crude lead contained high levels of impurities (requiring additional purification).

[0142] Comparative Example 4 skipped the replacement step and directly precipitated heavy metals, resulting in the failure of precious metals (Ag, Au) to be enriched. They precipitated along with the heavy metals in the non-heavy solids. The yield of silver and gold was only 2.9% and 4.1% of that in Example 1, respectively, resulting in serious waste of resources.

[0143] In the examples and comparative examples, the composition and content were detected by inductively coupled plasma atomic emission spectrometry.

[0144] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for efficient recovery of metals from sintering machine head dust leach liquor, characterized by, The method comprises the following steps: S1. The sintering machine head ash is treated by hydrochloric acid leaching, and an oxidizing agent is added during the leaching process. After solid-liquid separation, a leaching solution and a leaching solid are obtained, and the leaching solid is rinsed and returned to the sintering batching for use; S2. Iron powder is added to the leaching solution obtained in step S1 for replacement, and solid-liquid separation is performed to obtain a first post-replacement solution and a replacement solid; the amount of iron powder is 5-25 g / L, the replacement temperature is 50-70°C, and the replacement time is 1-3 h; An oxidizing agent is added to the first post-replacement solution, then a first precipitating agent is added to adjust the pH of the first post-replacement solution to 5-6, and after stirring for 0.5-1.5 h, solid-liquid separation is performed to obtain a first impurity removal post-solution and a first impurity removal solid; zinc powder is added to the first impurity removal post-solution for replacement, and after solid-liquid separation, crude lead and a second post-replacement solution are obtained; a first precipitating agent is added to the second post-replacement solution to adjust the pH of the second post-replacement solution to 11-13, and after solid-liquid separation, a heavy metal removal post-solution and a heavy metal removal solid are obtained; the amount of zinc powder is 1-5 g / L, the replacement temperature is room temperature, and the replacement time is 0.5-1.5 h; S3. An impurity removal agent is added to the heavy metal removal post-solution obtained in step S2 for impurity removal treatment, and after solid-liquid separation, a second impurity removal post-solution and a second impurity removal solid are obtained; The second impurity removal post-solution is subjected to evaporation treatment to obtain potassium and sodium salts; The first impurity removal solid and the second impurity removal solid are returned to the sintering batching for use; S4. The replacement solid obtained in step S2 is subjected to acid dissolution using a first acid solution to obtain a second acid dissolution solution and a second acid dissolution solid; The second acid dissolution solid is subjected to acid dissolution using a third acid solution, and an oxidizing agent is added during the acid dissolution process to obtain a silver-containing solid and a bismuth-containing solution; the bismuth-containing solution is added with a second precipitating agent, and after solid-liquid separation, bismuth oxychloride and a copper-containing solution are obtained; the copper-containing solution is mixed with the second acid dissolution solution, and then a third replacement agent is added to obtain crude copper; S5. The silver-containing solid obtained in step S4 is dissolved using a fourth acid solution to obtain a silver-containing solution and a gold-containing solid; a first reducing agent is added to the silver-containing solution to obtain sponge silver, and after smelting, silver ingots are obtained; the gold-containing solid is dissolved using aqua regia to obtain a gold-containing liquid, and a second reducing agent is added to the gold-containing liquid to obtain sponge gold, and after smelting, gold ingots are obtained.

2. The method of claim 1, wherein, In step S1, the concentration of hydrochloric acid is 1-3 mol / L.

3. The method of claim 1, wherein, In step S1, the leaching temperature is 60-90°C, the leaching time is 7-9 h, and the solid-liquid ratio of the leaching solution is 2-5:

1.

4. The method of claim 1, wherein, In steps S1 and S2, the oxidizing agent is any one or any combination of chlorine, hydrogen peroxide, calcium hypochlorite, sodium hypochlorite, and chlorine dioxide.

5. The method of claim 1, wherein, In step S2, the first precipitating agent is any one or any combination of lime slurry, calcium oxide, sodium hydroxide, and carbon dioxide.

6. The method of claim 1, wherein, In step S3, the impurity removal agent is any one or any combination of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

7. The method of claim 1, wherein, In step S4, when the first acid solution is dissolved: the liquid-solid ratio is maintained at 5-9:1, the dissolution temperature is 50-80°C, and the dissolution time is 2-4 h; The third acid solution is a hydrochloric acid solution or a sulfuric acid solution, the concentration of the third acid solution is 1-5 mol / L, and when the third acid solution is dissolved, the liquid-solid ratio is kept at 5-9:1, and the dissolution temperature is 50-80 DEG C; the oxidizing agent is any one or any combination of chlorine, hydrogen peroxide, calcium hypochlorite, sodium hypochlorite, and chlorine dioxide; the second precipitant is any one of quicklime and sodium hydroxide; and the third displacement agent is any one or any combination of iron powder, lead powder, and zinc powder.

8. The method of claim 1, wherein, In step S5, the fourth acid solution is a nitric acid solution, the concentration of the fourth acid solution is 1-5 mol / L, the first reducing agent is any one or any combination of sodium sulfite, glucose, glycine, and hydrazine hydrate, and the ratio of the molar amount of the first reducing agent to the molar amount of silver ions in the silver-containing solution is 1-3:

1.

9. The method of claim 1, wherein, In step S5, the second reducing agent is any one or any combination of sodium sulfite, sodium bisulfite, oxalic acid, formic acid, and hydrazine hydrate, and the ratio of the molar amount of the second reducing agent to the molar amount of gold ions in the gold-containing liquid is 1-4:1.

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