Method for the recovery and purification of valuable substances from cyanide-containing materials and their disposal water

Abstract

The application provides a cyanide-containing material and a method for recovering and purifying valuable substances in water treatment of the cyanide-containing material, and belongs to the field of resource recovery and environmental protection water treatment. The cyanide-containing material is subjected to microwave pretreatment to evaporate water in the material and obtain pretreated residue. Sodium hydroxide solution and a first reagent are added to the pretreated residue, and after stirring and reaction, solid-liquid separation is performed to obtain solid precipitate residue and alkaline dissolution solution. Sulfuric acid solution and a second reagent are added to the solid precipitate residue, and after stirring and reaction, solid-liquid separation is performed to obtain gold-silver alloy and acidic dissolution solution. The acidic dissolution solution is subjected to electrolysis treatment to recover copper, and the treated solution is returned to a production process for recycling. The alkaline dissolution solution is subjected to electrocatalytic treatment, and the treated solution is returned to the production process for recycling. Through the microwave pretreatment, acid and alkali solution treatment, electrolysis recovery and electrocatalytic end deep treatment process, efficient separation and recovery of valuable metals in the material and complete removal of pollutants in the water treatment are realized.

Description

Technical Field

[0001] This invention relates to the field of resource recycling and environmental protection water treatment technology, specifically to a method for recovering and purifying valuable substances in cyanide-containing materials and their treatment water. Background Technology

[0002] In the gold industry, cyanide leaching is a common process for extracting gold from gold ores. This process involves adding a large amount of sodium cyanide to leach gold from the ore. At the same time, valuable metals such as silver and copper are also leached out, generating cyanide-containing wastewater. To avoid adverse environmental impacts, economical and efficient treatment is necessary. Currently, the main methods for treating this type of cyanide-containing wastewater include the bleaching powder / hydrogen peroxide method, the Inco process, and ozone oxidation. The precipitates produced by these methods contain not only cyanide impurities but also valuable metals such as gold, silver, and copper, as well as pollutants such as cyanide and thiocyanate. Improper treatment can lead to the waste of valuable resources and serious environmental pollution.

[0003] The treatment and recovery of cyanide-containing materials mainly employs pyrometallurgical, hydrometallurgical, or a combination of both methods. Pyrometallurgical processes, particularly high-temperature methods, suffer from high energy consumption, incomplete treatment, and the inability to separate valuable substances. Hydrometallurgical processes, on the other hand, often struggle to effectively separate valuable metals from contaminants, or introduce new impurities, and their efficiency varies. Furthermore, the wastewater containing thiocyanate and cyanide generated during the recovery process is difficult to purify. For example, cyanide-containing materials from a mine in Yunnan Province have a moisture content as high as 61.82% and contain valuable metals such as gold, silver, and copper, as well as impurities like copper cyanide, cuprous cyanide, and cuprous thiocyanate. Current technologies cannot completely remove cyanide and thiocyanate contaminants from the liquid phase when treating such materials, making it difficult to separate and effectively recover valuable metals. This results in high treatment difficulty and cost, hindering industrial applications.

[0004] In view of this, it is necessary to design a method for the recovery and purification of valuable substances in cyanide-containing materials and their treatment water in order to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides a method for the recovery and purification of valuable substances in cyanide-containing materials and their treatment water, aiming to solve the technical problems of incomplete removal of pollutants, low efficiency of valuable metal recovery, complex process and high cost in the treatment of cyanide-containing materials in the prior art.

[0006] This application provides a method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water, including the following steps:

[0007] S1. Microwave pretreatment is performed on cyanide-containing materials to evaporate the moisture in the materials and obtain pretreated residue;

[0008] S2. Add sodium hydroxide solution and the first reagent to the pretreated residue obtained in step S1, stir and react, then separate the solid and liquid to obtain a solid precipitate residue and an alkaline solution;

[0009] S3. Add sulfuric acid solution and second reagent to the solid precipitate obtained in step S2, stir and react, then separate the solid and liquid to obtain a gold-silver alloy and an acidic solution;

[0010] S4. Electrolyze the acidic solution obtained in step S3 to recover copper, and return the treated solution to step S3 for recycling.

[0011] S5. The alkaline solution obtained in step S2 is subjected to electrocatalytic treatment, and the treated solution is returned to step S2 for recycling.

[0012] As a further improvement of this application, in step S2, the concentration of the sodium hydroxide solution is 5-10%, and the reaction time is 30-60 min.

[0013] As a further improvement of this application, in step S2, the first reagent is one or more of potassium peroxymonosulfate, GLDA, and potassium borohydride, wherein:

[0014] The mass ratio of potassium peroxymonosulfate to the total cyanide in the pretreated residue is (0.15~0.35):1;

[0015] The mass ratio of GLDA to copper in the pretreated slag is (0.25~0.75):1;

[0016] The mass ratio of potassium borohydride to the total cyanide in the pretreated residue is (0.4~0.8):1.

[0017] As a further improvement of this application, in step S3, the concentration of the sulfuric acid solution is 3-5%, and the reaction time is 30-60 min.

[0018] As a further improvement to this application, in step S3, the second reagent is one or more of sodium percarbonate, peracetic acid, and sodium dithionite, wherein:

[0019] The mass ratio of sodium percarbonate to the total cyanide in the solid precipitate is (1.5~2.5):1;

[0020] The mass ratio of peracetic acid to copper in the solid precipitate is (1~1.5):1;

[0021] The mass ratio of sodium dithionite to the total cyanide in the solid precipitate is (0.1~0.2):1.

[0022] As a further improvement of this application, in step S4, a porous pure copper plate is used as the cathode, a stainless steel plate is used as the anode, the reaction voltage is 3~3.5V, the current is 3.0~5.0A, and the reaction time is 60~300min.

[0023] As a further improvement of this application, in step S5, a transition metal plate coated with one or more catalytic materials selected from ruthenium, tin, and strontium is used as the anode, and a stainless steel plate is used as the cathode. The reaction voltage is 2.5~3.5V, the current is 5.0~8.0A, and the reaction time is 30~90min.

[0024] As a further improvement of this application, in step S1, the power of the microwave pretreatment is 300~500W and the reaction time is 10~20min.

[0025] As a further improvement of this application, the moisture content of the cyanide-containing material is 50-60%, and the moisture content of the pretreated residue is <5%.

[0026] As a further improvement of this application, the total cyanide content in the cyanide-containing material is less than 2.5%, the thiocyanate content is less than 5%, the copper content is greater than 30%, the silver content is not less than 1000 mg / kg, and the gold content is not less than 3 g / t.

[0027] The beneficial effects of this application are as follows:

[0028] This application provides a method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water. The method involves microwave pretreatment of the cyanide-containing material to evaporate moisture, yielding a pretreatment residue. Sodium hydroxide solution and a first reagent are added to the pretreatment residue, and after stirring and reaction, solid-liquid separation is performed to obtain a solid precipitate and an alkaline solution. Sulfuric acid solution and a second reagent are added to the solid precipitate, and after stirring and reaction, solid-liquid separation is performed to obtain a gold-silver alloy and an acidic solution. The acidic solution is electrolyzed to recover copper, and the treated solution is recycled. The alkaline solution is electrocatalyzed, and the treated solution is recycled. This application achieves efficient separation and recovery of valuable metals from materials and complete removal of pollutants from wastewater generated during the recovery process through microwave pretreatment, acid / alkali solution treatment, electrolytic recovery, and electrocatalytic end-stage deep treatment.

[0029] The entire process flow of this application is reasonably set up, the reaction parameters are easy to control, the operation is simple, and the operating cost is low. The treatment process is energy-saving and environmentally friendly, with advantages such as high reagent utilization, high treatment efficiency, full resource recovery, and the ability to recycle acid and alkali solutions during the process. The treatment process can achieve zero generation of wastewater and waste residue.

[0030] This application achieves a removal rate of over 99% for thiocyanate and total cyanide, a recovery rate of over 99% for gold and silver, and a recovery rate of over 95% for copper in materials by reasonably controlling the dosage of reagents in alkaline and acidic solvents. It also achieves high pollutant treatment efficiency and low treatment cost.

[0031] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0033] Figure 1 A flowchart illustrating the method for recovering and purifying valuable substances in cyanide-containing materials and their treatment water, as provided in the embodiments of this application. Detailed Implementation

[0034] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0036] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0037] For the treatment and recovery of cyanide-containing materials, pyrometallurgical, hydrometallurgical, or a combination of both methods are mainly used. In pyrometallurgical treatment, traditional high-temperature methods suffer from high energy consumption, insufficient treatment, and inability to separate valuable substances. In hydrometallurgical treatment, some methods are difficult to effectively separate valuable metals from pollutants, or may introduce new impurities. Moreover, the treatment efficiency varies, and the wastewater containing thiocyanate and cyanide generated in the recovery process is difficult to purify.

[0038] To address the technical problems of incomplete pollutant removal, low efficiency of valuable metal recovery, complex processes, and high costs in the treatment of cyanide-containing materials in existing technologies, this application provides a method for the recovery and purification of valuable substances in cyanide-containing materials and their treatment water. The method combines microwave pretreatment with acid-base dissolution, electrolytic recovery, and end-of-pipe deep treatment to achieve efficient recovery of valuable metals in the materials and complete removal of pollutants from the wastewater generated during the recovery process.

[0039] Please refer to Figure 1 This application provides a method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water, comprising the following steps:

[0040] S1. Microwave pretreatment is performed on cyanide-containing materials to evaporate the moisture in the materials and obtain pretreated residue;

[0041] S2. Add sodium hydroxide solution and the first reagent to the pretreated residue obtained in step S1, stir and react, then separate the solid and liquid to obtain a solid precipitate residue and an alkaline solution.

[0042] S3. Add sulfuric acid solution and the second reagent to the solid precipitate obtained in step S2, stir and react, then separate the solid and liquid to obtain a gold-silver alloy and an acidic solution;

[0043] S4. Electrolyze the acidic solution obtained in step S3 to recover copper. The treated solution is then returned to step S3 for recycling.

[0044] S5. The alkaline solution obtained in step S2 is subjected to electrocatalytic treatment, and the treated solution is returned to step S2 for recycling.

[0045] In the technical solution of this application embodiment, the cyanide-containing material is first rapidly heated using microwaves to obtain a pretreated slag. The moisture in the material is rapidly evaporated, significantly reducing the material's quality. Then, the pretreated slag is dissolved using an alkaline treatment solution (a mixture of sodium hydroxide solution and a first reagent) to obtain a solid precipitate and an alkaline solution. Under alkaline conditions, the first reagent effectively destroys cyanide, dissolves thiocyanate, and converts some metallic impurities into a soluble state, facilitating subsequent separation. The solid precipitate is then acid-dissolved using an acidic treatment solution (a mixture of sulfuric acid solution and a second reagent) to obtain a gold-silver alloy and an acidic solution. During this process, under acidic conditions, the second reagent further destroys residual cyanide and dissolves copper compounds (such as copper hydroxide and copper cyanide), generating copper sulfate solution. The solution is leached into an insoluble state, while precious metals such as gold and silver are enriched in an insoluble state to form alloys. These gold and silver alloys are returned to the smelting chamber for further separation and recovery. The acidic solution undergoes electrochemical copper recovery treatment. After treatment, the solution is replenished with reagents and sulfuric acid and returned to step S3 for recycling. During this process, copper ions are deposited as metallic copper at the cathode through an electrochemical reduction reaction. Simultaneously, residual cyanide is further oxidized and destroyed during electrolysis, achieving efficient copper recovery and purified solution reuse. The alkaline solution undergoes electrocatalytic treatment. Utilizing the remaining treatment reagents in the alkaline solution, under catalytic reaction conditions, residual cyanide and thiocyanate are deeply oxidized and decomposed into harmless substances. After treatment, the solution is replenished with reagents and sodium hydroxide and returned to step S2 for recycling, achieving efficient purification and recycling of the alkaline solution and reaching the goal of near-zero wastewater discharge. This application achieves efficient recovery of valuable metals such as gold, silver, and copper through stepwise leaching and electrolysis.

[0046] Furthermore, in some embodiments, in step S2, the concentration of the sodium hydroxide solution is 5-10%, and the reaction time is 30-60 min.

[0047] In the technical solution of this application embodiment, sodium hydroxide provides the necessary alkaline environment, and the sodium hydroxide solution and the first reagent form an alkaline treatment solution, which dissolves part of the cyanide and most of the thiocyanate in the cyanide-containing material.

[0048] Furthermore, in some embodiments, the first agent is one or more of potassium peroxymonosulfate, GLDA (tetrasodium glutamate diacetate), and potassium borohydride, wherein:

[0049] The mass ratio of potassium peroxymonosulfate to total cyanide in the pretreated residue is (0.15~0.35):1;

[0050] The mass ratio of GLDA to copper in the pretreated slag is (0.25~0.75):1;

[0051] The mass ratio of potassium borohydride to total cyanide in the pretreated residue is (0.4~0.8):1.

[0052] In the technical solution of this application embodiment, the first reagent is a deep purification reagent that assists in the treatment of cyanide and thiocyanate during alkaline leaching, enhancing the decomposition of cyanide. The optimal reagent combination and dosage can be selected based on the actual composition of the cyanide-containing material (such as cyanide content, copper content, other impurities, etc.) and cost budget to achieve the best purification effect and economic benefits. Preferably, the first reagent consists of potassium peroxymonosulfate and GLDA. Through the synergistic effect of potassium peroxymonosulfate (oxidant) and GLDA (chelating agent), the interference of copper on the cyanide oxidation process is eliminated, thereby enabling potassium peroxymonosulfate to more efficiently and specifically oxidize and degrade cyanide and thiocyanate. Potassium peroxymonosulfate (Potassium peroxymonosulfate) is a strong oxidizing agent. In aqueous solution, it undergoes a chain reaction, continuously generating nascent oxygen, free hydroxyl groups, hydrogen peroxide, and other active components. This oxidizes and destroys cyanide. Free hydroxyl groups are highly reactive free radicals that can attack the chemical bonds of cyanide, oxidizing it into low-toxicity or non-toxic substances (such as cyanate, carbon dioxide, etc.), thus achieving the process goal of destroying the cyanide structure. The oxidizing effect of nascent oxygen can weaken the stability of thiocyanate, which is mainly composed of cuprous thiocyanate, and promote its dissolution into the alkaline solution. GLDA is a highly efficient and green chelating agent. In the process, the slag contains copper, and copper ions are prone to precipitate under alkaline conditions. GLDA forms a stable chelate by chelating copper ions, avoiding precipitation and ensuring the continuous dissolution of cuprous thiocyanate (if copper precipitates, it will encapsulate thiocyanate and hinder dissolution). After chelating metal ions, GLDA can reduce the interference of metals on the oxidation reaction (such as metal ions catalyzing the decomposition of potassium peroxymonosulfate), maintaining the high efficiency of the oxidation reaction. Potassium hydrogen sulfate oxidizes cyanide and assists in the dissolution of thiocyanate, while GLDA chelates metals to ensure dissolution. The combination of the two makes the process of thiocyanate dissolving into the solution and the destruction of cyanide more thorough.

[0053] Furthermore, in some embodiments, in step S3, the concentration of the sulfuric acid solution is 3-5%, and the reaction time is 30-60 min.

[0054] In the technical solution of this application embodiment, a sulfuric acid concentration of 3-5% is sufficient to provide the necessary acidic environment, which can effectively dissolve copper-containing compounds such as copper hydroxide and cuprous cyanide and convert them into soluble copper sulfate, while avoiding excessive acidity that could lead to aggravated equipment corrosion or the generation of excessive acid mist, thus increasing the load on subsequent processing.

[0055] Furthermore, in some embodiments, the second agent is one or more of sodium percarbonate, peracetic acid, and sodium dithionite, wherein:

[0056] The mass ratio of sodium percarbonate to total cyanide in the solid precipitate is (1.5~2.5):1;

[0057] The mass ratio of peracetic acid to copper in the solid precipitate is (1~1.5):1;

[0058] The mass ratio of sodium dithionite to total cyanide in the solid precipitate is (0.1~0.2):1.

[0059] In the technical solution of this application embodiment, sodium percarbonate decomposes in water to produce hydrogen peroxide and sodium carbonate. Under acidic conditions, hydrogen peroxide further generates highly oxidizing ·OH free radicals, which can efficiently destroy the chemical structure of cyanide ions, oxidizing them into low-toxicity cyanate or carbon dioxide and nitrogen gas, with a mass ratio of (1.5~2.5):1. This ensures sufficient free radical generation, achieving deep removal of cyanide while avoiding excessive addition that would waste reagents and burden subsequent treatment. Peracetic acid possesses both oxidizing and complexing abilities with metal ions, participating in the destruction of cyanide and reacting with copper ions in the solution to prevent copper ions from re-complexing or precipitating, thereby improving the subsequent electrolytic recovery rate of copper. Controlling its mass ratio to copper at (1~1.5):1 can effectively assist in cyanide degradation while optimizing the stabilization and availability of copper ions. Sodium dithionite, as a strong reducing agent, can effectively reduce any high-valence metal ions that may be present in the system, preventing high-valence metals from promoting cyanide resolution or generating competitive side reactions. It also assists in destroying the cyanide complex structure. A relatively low mass ratio (0.1~0.2):1 can exert its reduction regulation effect; excessive use may lead to ineffective acid consumption or the introduction of excessive impurities.

[0060] Furthermore, in some embodiments, in step S4, a porous pure copper plate is used as the cathode, a stainless steel plate is used as the anode, the reaction voltage is 3~3.5V, the current is 3.0~5.0A, and the reaction time is 60~300min.

[0061] In the technical solution of this application embodiment, by optimizing the electrode material, reaction voltage, and reaction current, and with sufficient reaction time, the dual objectives of efficient copper recovery and deep solution purification are achieved, ensuring the technical feasibility and economic rationality of the entire resource recovery process. Specifically, the mass ratio of the reagent to the total cyanide in the acidic solution is (0.1~0.2):1; if the mass ratio of the remaining treatment reagent to the total cyanide is less than 0.1, a second reagent is added to bring the mass ratio of the treatment reagent to the total cyanide in the acidic solution to (0.1~0.2):1, for removing cyanide from the acidic solution.

[0062] Furthermore, in some embodiments, in step S5, a transition metal plate coated with one or more catalytic materials selected from ruthenium, tin, and strontium is used as the anode, and a stainless steel plate is used as the cathode. The reaction voltage is 2.5~3.5V, the current is 5.0~8.0A, and the reaction time is 30~90min.

[0063] In the technical solution of this application embodiment, by employing a highly active catalytic anode, optimizing the reaction voltage and intensity, and providing sufficient reaction time, a synergistic effect is achieved to efficiently and deeply mineralize and destroy recalcitrant pollutants, ensuring the quality of the final effluent and ultimately guaranteeing the closed-loop circulation and near-zero emission targets of the entire process system. The anode plate can use porous iron materials as catalyst supports, or a manganese-copper composite as a catalyst support. Specifically, the mass ratio of the remaining reagents in the alkaline solution to the mass of thiocyanate and total cyanide is (0.3~0.5):1; if the mass ratio of the remaining deep purification reagents in the alkaline solution to the mass of thiocyanate and total cyanide is less than 0.3, then deep purification reagents are added until the mass ratio reaches (0.3~0.5):1. After treatment, the removal rate of thiocyanate and cyanide can reach over 95%.

[0064] Furthermore, in some embodiments, in step S1, the microwave pretreatment power is 300-500 W, and the reaction time is 10-20 min. The moisture content of the cyanide-containing material is 50-60%, and the moisture content of the pretreated residue is <5%.

[0065] In the technical solution of this application embodiment, cyanide-containing materials are processed by a microwave reactor, and the materials are fully and uniformly heated by a conveyor belt, thereby achieving rapid and deep dehydration of high-moisture and cyanide-containing materials.

[0066] Furthermore, in some embodiments, the total cyanide content in the cyanide-containing material is less than 2.5%, the thiocyanate content is less than 5%, the copper content is greater than 30%, the silver content is not less than 1000 mg / kg, and the gold content is not less than 3 g / t.

[0067] In the technical solution of this application embodiment, for secondary cyanide-containing materials rich in copper and containing a considerable amount of gold and silver, the method of this application can achieve efficient extraction of copper, gold and silver and complete destruction of cyanide / thiocyanate, which is technically feasible, economically reasonable and environmentally friendly.

[0068] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0069] Example 1

[0070] This embodiment provides a method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water. The cyanide-containing material from a gold mine has a total cyanide content of 21.9 g / kg, a copper content of 50.21%, a silver content of 1459.4 mg / kg, and a gold content of 6.93 g / t. The specific steps include:

[0071] S1. The cyanide-containing material is processed by a microwave reactor. The material is fully and evenly heated by a conveyor belt. The power is adjusted to 500W. The reaction residence time of the cyanide-containing material is 20 minutes. After the reaction, the mass of the remaining material is 31.2% of the initial material, and a pre-treated residue is obtained. The moisture in the treated material is quickly evaporated to dryness. Compared with the traditional electric heating method, the processing time is shortened and the processing cost is significantly reduced.

[0072] S2. The pretreated slag is fed into an alkaline treatment stirring tank. Its main components are gold, silver, copper hydroxide, cuprous thiocyanate, copper cyanide, and other cyanides. A 5% sodium hydroxide solution and the first reagent are added. After stirring and reacting for 60 minutes, solid-liquid separation is performed through a cluster filter to obtain a solid precipitate and an alkaline solution. The first reagent consists of potassium peroxymonosulfate and GLDA. The mass ratio of potassium peroxymonosulfate to the total cyanide in the slag is 0.25:1, and the mass ratio of GLDA to copper in the slag is 0.5:1. In the alkaline solution obtained after dissolving the material, the concentration of thiocyanate is 9100 mg / L, the concentration of total cyanide is 26 mg / L, the concentration of copper ions is 25 mg / L, and the remaining material is 9.2% of the initial material.

[0073] S3. The solid precipitate is fed into the acid dissolution tank via a screw feeder. Its main components are gold, silver, copper hydroxide, and copper cyanide. A 3% sulfuric acid solution and a second reagent are added, and the mixture is stirred for 60 minutes. The acid dissolution tank is connected to an absorption port, where the waste gas generated during acidification is absorbed by the alkaline solution. After complete dissolution, the mixture is filtered through a cluster filter to obtain a gold-silver alloy and an acidic solution. The second reagent consists of sodium percarbonate, peracetic acid, and sodium dithionite. Sodium percarbonate reacts with the total cyanide in the solid precipitate. The mass ratio of peracetic acid to copper ions in the solid precipitate was 2.5:1, the mass ratio of sodium dithionite to total cyanide in the solid precipitate was 1.5:1, and the mass ratio of sodium dithionite to total cyanide in the solid precipitate was 0.2:1. In the acidic solution obtained after dissolving the materials, the concentration of thiocyanate was 0.82 mg / L, the concentration of total cyanide was 1.2 mg / L, and the concentration of copper ions was 12342 mg / L. The resulting gold-silver alloy accounted for 0.71% of the initial material, with a gold content of 6.2% and a silver content of 91.3%.

[0074] S4. The acidic solution obtained in step S3 is electrolyzed to recover copper. A porous pure copper plate is used as the cathode and a stainless steel plate as the anode. The reaction voltage is 3V, the reaction current is controlled at 4.14A, and the reaction is carried out for 300 minutes. After treatment, the solution is replenished with reagents and sulfuric acid and returned to step S3 for recycling. Sodium percarbonate is added to the acidic solution to make the mass ratio of reagent to total cyanide 0.2:1. After electrochemical recovery, the concentration of thiocyanate in the solution is less than 0.2 mg / L, the concentration of total cyanide is less than 0.2 mg / L, the concentration of copper ions is 321 mg / L, and the copper recovery rate is 97.4%.

[0075] S5. The alkaline solution obtained in step S2 is subjected to electrocatalytic treatment. The reaction voltage is 3V, the reaction current is 5.89A, and the reaction time is 90min. After treatment, the solution is replenished with reagents and sodium hydroxide and returned to step S2 for recycling. The alkaline solution obtained needs to be added with a deep purification reagent until the mass ratio of the total reagent to thiocyanate and total cyanide is 0.3:1. The alkaline solution is then deeply purified using the deep purification reagent. The catalyst support of the anode is iron, and the effective component of the catalyst plated on the surface of the anode is a combination of ruthenium and tin alloy. The cathode is a stainless steel plate. After treatment, the concentration of thiocyanate in the solution is 42mg / L, the concentration of total cyanide is less than 0.2mg / L, the concentration of copper ions is less than 0.2mg / L, the removal rate of thiocyanate is greater than 99%, and the removal rate of cyanide is greater than 99%.

[0076] Example 2

[0077] This embodiment provides a method for recovering and purifying cyanide-containing materials and valuable substances in their treatment water. Compared with Embodiment 1, the only difference is that in step S2, the mass ratio of potassium peroxymonosulfate to total cyanide in the slag is 0.35:1, and the mass ratio of GLDA to copper in the slag is 0.75:1. Other experimental parameters and conditions are basically the same as in Embodiment 1, and will not be repeated here.

[0078] Example 3

[0079] This embodiment provides a method for recovering and purifying cyanide-containing materials and valuable substances in their treatment water. Compared with Embodiment 1, the only difference is that in step S2, the mass ratio of potassium peroxymonosulfate to total cyanide in the slag is 0.15:1, and the mass ratio of GLDA to copper in the slag is 0.25:1. Other experimental parameters and conditions are basically the same as in Embodiment 1, and will not be repeated here.

[0080] Example 4

[0081] This embodiment provides a method for recovering and purifying valuable substances in cyanide-containing materials and their treatment water. Compared with Embodiment 1, the only difference is that in step S3, the mass ratio of sodium percarbonate to total cyanide in the solid precipitate is 1.5:1, the mass ratio of peracetic acid to copper ions in the solid precipitate is 1:1, and the mass ratio of sodium dithionite to total cyanide in the solid precipitate is 0.1:1. Other experimental parameters and conditions are basically the same as in Embodiment 1, and will not be repeated here.

[0082] After acid dissolution, a gold-silver alloy was obtained, which accounted for 0.69% of the initial material, with a gold content of 6.1% and a silver content of 92.5%.

[0083] Comparative Example 1

[0084] Comparative Example 1 provides a method for recovering and purifying valuable substances in cyanide-containing materials and their treatment water. Compared with Example 1, the only difference is that in step S2, the mass ratio of potassium peroxymonosulfate to total cyanide in the slag is 0.1:1, and the mass ratio of GLDA to copper in the slag is 0.2:1. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0085] Comparative Example 1, after acid dissolution treatment, yielded a product with poor purity. The reason is that the dosage of the treatment agent added in step S2 was insufficient. The agent was coupled in water, and due to the insufficient agent, the treatment effect of the pollutants was poor. There was too much thiocyanate and cyanide remaining in the material. After entering step S3, the pollutants were still present, resulting in a product with poor purity.

[0086] Comparative Example 2

[0087] Comparative Example 2 provides a method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water. The only difference from Example 1 is that in step S4, when performing electrochemical recovery treatment, the reaction voltage is 1.5 V and the reaction current is controlled at 2.14 A. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0088] Under these conditions, the copper recovery rate after electrochemical treatment was poor, at only 53.1%. This is because the low current in the electrochemical recovery reaction prevented copper sulfate in the acid solution from efficiently accumulating at the cathode, thus reducing the copper recovery rate.

[0089] Comparative Example 3

[0090] Comparative Example 3 provides a method for recovering and purifying valuable substances in cyanide-containing materials and their treatment water. Compared with Example 1, the only difference is that in step S3, the mass ratio of sodium percarbonate to total cyanide in the solid precipitate is 1:1, the mass ratio of peracetic acid to copper ions in the solid precipitate is 0.5:1, and the mass ratio of sodium dithionite to total cyanide in the solid precipitate is 0.1:1. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0091] In Comparative Example 3, the dosage of the acid solution was too low, and the reagent failed to fully destroy the residual cyanide in the slag under acidic conditions, resulting in the presence of thiocyanate and cyanide impurities in the gold-silver alloy. The product purity was poor, with a gold content of 2.3% and a silver content of only 46.7%.

[0092] Example 5

[0093] This embodiment provides a method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water. The cyanide-containing material from a gold mine has a total cyanide content of 11.23 g / kg, a copper content of 40.34%, a silver content of 1345.4 mg / kg, and a gold content of 5.1 g / t. The specific steps include:

[0094] S1. The cyanide-containing material is processed by a microwave reactor. The material is fully and evenly heated by a conveyor belt. The power is adjusted to 400W. The reaction residence time of the cyanide-containing material is 20min. The mass of the remaining material after the reaction is 43.1% of the initial material, and a pretreated residue is obtained.

[0095] S2. The pretreated slag is fed into an alkaline treatment stirring tank. Its main components are gold, silver, copper hydroxide, cuprous thiocyanate, copper cyanide, and other cyanides. A 10% sodium hydroxide solution and the first reagent are added. After stirring and reacting for 60 minutes, solid-liquid separation is performed through a cluster filter to obtain a solid precipitate and an alkaline solution. The first reagent consists of potassium peroxymonosulfate and GLDA. The mass ratio of potassium peroxymonosulfate to the total cyanide in the slag is 0.3:1, and the mass ratio of GLDA to copper in the slag is 0.5:1. In the alkaline solution obtained after dissolving the material, the concentration of thiocyanate is 7634 mg / L, the concentration of total cyanide is 16 mg / L, the concentration of copper ions is 0.41 mg / L, and the remaining material is 9% of the initial material.

[0096] S3. The solid precipitate is fed into the acid dissolving tank via a screw feeder. Its main components are gold, silver, copper hydroxide, and copper cyanide. A 5% sulfuric acid solution and a second reagent are added, and the mixture is stirred for 60 minutes. The acid dissolving tank is connected to an absorption port, where the waste gas generated by acidification is absorbed by the alkaline solution. After complete dissolution, the mixture is filtered through a cluster filter to obtain a gold-silver alloy and an acidic solution. The second reagent consists of sodium percarbonate, peracetic acid, and sodium dithionite. The mass ratio of sodium percarbonate to total cyanide in the solid precipitate is 2.2:1, the mass ratio of peracetic acid to copper ions in the solid precipitate is 1:1, and the mass ratio of sodium dithionite to total cyanide in the solid precipitate is 0.2:1. In the acidic solution obtained after dissolving the material, the concentration of thiocyanate is 0.1 mg / L, the concentration of total cyanide is 0.2 mg / L, and the concentration of copper ions is 9136 mg / L. The mass of the obtained gold-silver alloy is 0.64% of the initial material, with a gold content of 7.1% and a silver content of 92.2%.

[0097] S4. The acidic solution obtained in step S3 is electrolyzed to recover copper. A porous pure copper plate is used as the cathode and a stainless steel plate as the anode. The reaction voltage is 3V, the reaction current is controlled at 4.93A, and the reaction is carried out for 240 minutes. After treatment, the solution is replenished with reagents and sulfuric acid and returned to step S3 for recycling. Sodium percarbonate is added to the acidic solution to make the mass ratio of reagent to total cyanide 0.2:1. After electrochemical recovery, the concentration of thiocyanate in the solution is less than 0.2 mg / L, the concentration of total cyanide is less than 0.2 mg / L, the concentration of copper ions is 147 mg / L, and the copper recovery rate is 98.4%.

[0098] S5. The alkaline solution obtained in step S2 is subjected to electrocatalytic treatment at a reaction voltage of 3V, a reaction current of 6.76A, and a reaction time of 90min. After treatment, the solution is replenished with reagents and sodium hydroxide and returned to step S2 for recycling. The alkaline solution obtained needs to be treated with a deep purification reagent until the mass ratio of the total reagent to thiocyanate and total cyanide is 0.35:1. The alkaline solution is then deeply purified using the deep purification reagent. The catalyst support at the anode is iron oxide, and the effective catalyst component plated on the surface of the anode is a combination of ruthenium, tin, and strontium alloy. The cathode is a stainless steel plate. After treatment, the concentration of thiocyanate in the solution is 12mg / L, the concentration of total cyanide is less than 0.2mg / L, the concentration of copper ions is less than 0.2mg / L, the removal rate of thiocyanate is greater than 99%, and the removal rate of cyanide is greater than 99%.

[0099] Example 6

[0100] This embodiment provides a method for recovering and purifying cyanide-containing materials and valuable substances in their treatment water. Compared with Example 5, the only difference is that in step S5, a deep purification agent is added to the alkaline solution until the mass ratio of the total agent mass to the mass ratio of thiocyanate and total cyanide is 0.5:1. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0101] After electrocatalytic reaction treatment, the removal rate of thiocyanate is 99.8%, the recycled water meets the requirements for reuse and discharge standards, and the unit can operate well and stably.

[0102] Comparative Example 4

[0103] Comparative Example 4 provides a method for recovering and purifying valuable substances in cyanide-containing materials and their treatment water. The only difference from Example 5 is that in step S5, the catalyst plate support is made of stainless steel. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0104] After electrocatalytic reaction treatment, the removal rate of thiocyanate was 31%, which meant that the recycled water could not be reused in step S2. The reason is that the electrode plates used in the electrocatalytic reaction step are made of stainless steel, which cannot provide sufficient electrocatalytic active sites, resulting in poor electrocatalytic reaction and failure to fully activate the deep treatment reagents. This reduced the removal rate of thiocyanate, making the recycled water unusable.

[0105] Comparative Example 5

[0106] Comparative Example 5 provides a method for recovering and purifying valuable substances in cyanide-containing materials and their treatment water. The only difference from Example 5 is that in step S5, the reaction voltage is 1.5V and the reaction current is 2.84A. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0107] After electrocatalytic reaction treatment, the removal rate of thiocyanate was only 16.8%, meaning the recycled water could not be reused in step S2. The reason is that the treatment voltage selected in the electrocatalytic reaction step was too low, affecting the treatment effect and reducing the thiocyanate removal rate, thus preventing the reuse of the recycled water.

[0108] Example 7

[0109] This embodiment provides a method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water. The cyanide-containing material from a gold mine has a total cyanide content of 7.23 g / kg, a copper content of 46.54%, a silver content of 1124.3 mg / kg, and a gold content of 8.2 g / t. The specific steps include:

[0110] S1. The cyanide-containing material is processed by a microwave reactor. The material is fully and evenly heated by a conveyor belt. The power is adjusted to 450W. The reaction residence time of the cyanide-containing material is 20min. The mass of the remaining material after the reaction is 52.0% of the initial material, and a pretreated residue is obtained.

[0111] S2. The pretreated slag is fed into an alkaline treatment stirring tank. Its main components are gold, silver, copper hydroxide, cuprous thiocyanate, copper cyanide, and other cyanides. A 10% sodium hydroxide solution and the first reagent are added. After stirring and reacting for 60 minutes, solid-liquid separation is performed through a cluster filter to obtain a solid precipitate and an alkaline solution. The first reagent consists of potassium peroxymonosulfate and GLDA. The mass ratio of potassium peroxymonosulfate to the total cyanide in the slag is 0.22:1, and the mass ratio of GLDA to copper in the slag is 0.25:1. In the alkaline solution obtained after dissolving the material, the concentration of thiocyanate is 4522 mg / L, the concentration of total cyanide is 2.4 mg / L, the concentration of copper ions is 13.4 mg / L, and the remaining material is 7.8% of the initial material.

[0112] S3. The solid precipitate, mainly composed of gold, silver, copper hydroxide, and copper cyanide, is fed into an acid dissolving tank via a screw feeder. A 5% sulfuric acid solution and a second reagent are added, and the mixture is stirred for 60 minutes. The acid dissolving tank is connected to an absorption port, where the waste gas generated during acidification is absorbed by the alkaline solution. After complete dissolution, the mixture is filtered through a cluster filter to obtain a gold-silver alloy and an acidic solution. The second reagent consists of sodium percarbonate, peracetic acid, and sodium dithionite. The mass ratio of sodium percarbonate to total cyanide in the solid precipitate is 2.1:1, the mass ratio of peracetic acid to copper ions in the solid precipitate is 1.3:1, and the mass ratio of sodium dithionite to total cyanide in the solid precipitate is 0.2:1. The acidic solution obtained after dissolving the materials has a thiocyanate concentration of 0.2 mg / L and a total cyanide concentration of 0.05 mg / L. With a copper ion concentration of 8257 mg / L, the resulting gold-silver alloy accounted for 0.73% of the initial material, containing 8.6% gold and 91.1% silver.

[0113] S4. The acidic solution obtained in step S3 is electrolyzed to recover copper. A porous pure copper plate is used as the cathode and a stainless steel plate as the anode. The reaction voltage is 3V, the reaction current is controlled at 4.82A, and the reaction is carried out for 200 minutes. After treatment, the solution is replenished with reagents and sulfuric acid and returned to step S3 for recycling. Sodium percarbonate is added to the acidic solution to make the mass ratio of reagent to total cyanide 0.2:1. After electrochemical recovery, the concentration of thiocyanate in the solution is less than 0.2 mg / L, the concentration of total cyanide is less than 0.2 mg / L, the concentration of copper ions is 112 mg / L, and the copper recovery rate is 98.6%.

[0114] S5. The alkaline solution obtained in step S2 is subjected to electrocatalytic treatment at a reaction voltage of 3V, a reaction current of 7.87A, and a reaction time of 90min. After treatment, the solution is replenished with reagents and sodium hydroxide and returned to step S2 for recycling. The alkaline solution obtained needs to be treated with a deep purification reagent until the mass ratio of the total reagent to thiocyanate and total cyanide is 0.3:1. The alkaline solution is then deeply purified using the deep purification reagent. The catalyst support at the anode is manganese oxide, and the effective catalyst component plated on the surface of the anode is a combination of ruthenium and tin alloy. The cathode is a stainless steel plate. After treatment, the concentration of thiocyanate in the solution is 4.8mg / L, the concentration of total cyanide is less than 0.2mg / L, the concentration of copper ions is less than 0.2mg / L, the removal rate of thiocyanate is greater than 99%, and the removal rate of cyanide is greater than 99%.

[0115] Table 1. Test results of examples and comparative examples.

[0116]

[0117] In summary, the present application provides a method for the recovery and purification of valuable substances in cyanide-containing materials and their treatment water. Using alkaline solvents such as potassium peroxymonosulfate, GLDA, and potassium borohydride, and acidic solvents such as sodium percarbonate, peracetic acid, and sodium dithionite, the method achieves a removal rate of thiocyanate and total cyanide greater than 99%. By combining electrochemical recovery and electrocatalytic deep treatment methods, the recovery rate of gold and silver can exceed 99%, and the recovery rate of copper can exceed 95%. The treatment cost is low, and the method can separate high-value gold, silver, and copper, resulting in extremely high added value. Furthermore, the end-of-pipe wastewater purification method can efficiently remove thiocyanate and cyanide.

[0118] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water, characterized in that, Includes the following steps: S1. Microwave pretreatment is performed on cyanide-containing materials to evaporate the moisture in the materials and obtain pretreated residue; S2. Add sodium hydroxide solution and the first reagent to the pretreated residue obtained in step S1, stir and react, then separate the solid and liquid to obtain a solid precipitate residue and an alkaline solution; The concentration of the sodium hydroxide solution is 5-10%, and the reaction time is 30-60 min; The first reagent is one or more of potassium peroxymonosulfate, GLDA, and potassium borohydride, wherein: the mass ratio of potassium peroxymonosulfate to the total cyanide in the pretreated slag is (0.15~0.35):1; the mass ratio of GLDA to copper in the pretreated slag is (0.25~0.75):1; and the mass ratio of potassium borohydride to the total cyanide in the pretreated slag is (0.4~0.8):

1. S3. Add sulfuric acid solution and second reagent to the solid precipitate obtained in step S2, stir and react, then separate the solid and liquid to obtain a gold-silver alloy and an acidic solution; The concentration of the sulfuric acid solution is 3-5%, and the reaction time is 30-60 min; The second reagent is one or more of sodium percarbonate, peracetic acid, and sodium dithionite, wherein: the mass ratio of sodium percarbonate to the total cyanide in the solid precipitate is (1.5~2.5):1; the mass ratio of peracetic acid to copper in the solid precipitate is (1~1.5):1; and the mass ratio of sodium dithionite to the total cyanide in the solid precipitate is (0.1~0.2):

1. S4. Electrolyze the acidic solution obtained in step S3 to recover copper, and return the treated solution to step S3 for recycling. S5. The alkaline solution obtained in step S2 is subjected to electrocatalytic treatment, and the treated solution is returned to step S2 for recycling.

2. The method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water according to claim 1, characterized in that, In step S4, a porous pure copper plate is used as the cathode and a stainless steel plate is used as the anode. The reaction voltage is 3~3.5V, the current is 3.0~5.0A, and the reaction time is 60~300min.

3. The method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water according to claim 1, characterized in that, In step S5, a transition metal plate coated with one or more catalytic materials selected from ruthenium, tin, and strontium is used as the anode, and a stainless steel plate is used as the cathode. The reaction voltage is 2.5~3.5V, the current is 5.0~8.0A, and the reaction time is 30~90min.

4. The method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water according to claim 1, characterized in that, In step S1, the power of the microwave pretreatment is 300~500W, and the reaction time is 10~20min.

5. The method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water according to claim 4, characterized in that, The cyanide-containing material has a moisture content of 50-60%, and the pretreated residue has a moisture content of <5%.

6. The method for recovering and purifying valuable substances from cyanide-containing materials and their treatment water according to claim 1, characterized in that, The cyanide-containing material contains less than 2.5% total cyanide, less than 5% thiocyanate, more than 30% copper, not less than 1000 mg / kg silver, and not less than 3 g / t gold.

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