Short-process treatment method for silver anode slime of silver electrolysis

Abstract

The invention belongs to the technical field of non-ferrous metallurgy precious metal wet smelting, and particularly relates to a silver electrolysis silver anode slime short-process treatment method which comprises the steps that an alcohol medium is added into silver anode slime for ultrasonic vibration, simple substances and compounds existing in a silver anode are dispersed, screen underflow is subjected to solid-liquid separation, and filter residues and filtrate are obtained; returning filtrate, vibrating and dispersing; and casting a silver anode plate from oversize products by a back fire method. Obtained filter residues are subjected to chlorination leaching, rare and precious metal elements such as gold, platinum, palladium and rhodium are converted into chlorination liquid of a chlorination water solution, and elemental silver and silver compounds in the filter residues are converted into chlorination residues of silver chloride. Returning the chlorination liquid to the gold separation or gold immersion in the gold extraction process to obtain coarse gold powder rich in platinum, palladium and rhodium, and refining to obtain a gold ingot; and the chlorination residues are directly returned to the silver extraction process for reduction or silver separation, and obtained high-quality coarse silver powder is used for electrolysis. The method is simple in process and relatively short in flow, and realizes cyclic application of material resources.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgical precious metal smelting, and in particular relates to a short-process treatment method for silver electrolytic silver anode mud. Background Art

[0002] Silver electrolysis anode mud is a by-product of the silver electrolytic refining process. The silver anode mud rate is generally 0.7-3%. The traditional anode mud mainly consists of: 30-40% silver, 6-10% gold, 0.2-1.0% platinum, 0.5-1.0% palladium, 0.5-1.5% copper, 0.4-1.0% lead and 2.0-5.0% bismuth. However, with the application of high current density silver electrolysis technology, the quality of silver anode plates is higher, and the silver anode mud produced has a higher silver content than the silver anode mud produced by traditional low current density silver electrolysis. At present, the main methods for treating silver anode mud are nitric acid leaching-chlorination gold separation-gold palladium purification, nitric acid leaching-aqua regia gold dissolution-gold powder reduction, etc.

[0003] After searching, Chinese patent ZL202010209687.5 discloses a method for efficiently separating silver, platinum and palladium from silver anode mud. The method uses nitric acid and an oxidant to oxidize and leach the anode mud, recover silver, platinum and palladium from the leachate, and then recover gold from the silver separation slag. Chinese patent ZL201510563937.4 discloses a comprehensive recovery method for platinum and palladium from silver anode mud. In view of the problem of platinum and palladium dispersion, platinum and palladium are recovered from the silver separation liquid and the leaching slag respectively, thereby improving the recovery rate of platinum and palladium; Chinese patent ZL201010621176.0 discloses a treatment process for silver anode mud. By optimizing the process parameters of nitric acid silver separation, silver and palladium in the silver anode mud are leached, and gold and platinum enter the leaching slag, thereby avoiding the dispersion of platinum and palladium. Chinese patent CN202310761435.7 discloses a method for recovering gold and silver from silver anode mud. Through the process of detection, water washing, drying, melting, ash blowing refining, gold separation, and casting, gold and silver are made into alloys during the pyrometallurgical smelting process, and then silver nitrate is separated to obtain silver nitrate solution for electrolysis to obtain silver separation slag and then enter gold separation to recover gold. This technology can realize the recovery of gold and silver, but the process is long. It is suitable for processing high-gold and high-silver materials with silver anode mud as auxiliary materials, but it is not suitable for processing silver anode mud alone.

[0004] However, the existing technology has the disadvantages of a long processing flow, low gold and silver leaching rates, and easy loss of precious metals in the process; the silver nitrate separation process cannot completely separate the platinum and palladium in the silver anode mud, and the recovery rate is low. At the same time, the nitric acid-containing wastewater produced by the introduction of nitric acid production is difficult to treat, and the nitrogen oxides produced are difficult to control.

[0005] Therefore, developing a silver electrolysis anode mud treatment method with simple process flow, low processing cost, high recovery rate of rare and precious metals, and more environmentally friendly is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0006] In view of this, in order to solve the problems existing in the prior art, the present invention provides a short-process treatment method for silver electrolysis silver anode mud. This method is aimed at high-silver silver anode mud and can be simply grafted into the existing anode mud treatment process to achieve recycling and avoid the loss of rare and precious metals in the treatment process.

[0007] In order to achieve the above object, the purpose of the present invention is to provide a short-process treatment method for silver electrolysis silver anode mud.

[0008] A short-process method for treating silver anode mud in silver electrolysis, the specific steps comprising:

[0009] (1) Ultrasonic vibration dispersion-screening treatment: After adding alcohol medium to the silver anode mud, ultrasonic vibration is performed to disperse the elements and compounds present in the silver anode; after vibrating for 10 to 50 minutes, the slurry is screened; the underscreen is subjected to solid-liquid separation to obtain filter residue and filtrate, and the filtrate is returned to the vibration dispersion; the overscreen is annealed to melt and cast the silver anode plate;

[0010] (2) Chlorination leaching: adding hydrochloric acid and an oxidant to the filter residue obtained in step (1), heating and stirring to leach, and separating the solid and the liquid to obtain a chlorinated solution 1 and chlorinated residue;

[0011] (3) returning the chlorinated solution 1 obtained in step (2) to the copper anode mud chlorination gold separation or gold precipitation process to recover rare and precious metals such as gold, platinum, palladium and rhodium;

[0012] (4) The chlorinated slag obtained in step (2) is purified by chlorination to remove impurities, and then returned to the reduction and silver precipitation section of the silver extraction process to obtain crude silver powder, which enters the next refining stage.

[0013] The present invention adopts a physical classification screening method of ultrasonic vibration-screening, which can easily directly recover high-silver-containing particles with large particle size distribution in the silver anode, and return the silver anode to cast into a silver anode plate for direct electrolysis, avoiding entering the process and improving the silver recovery rate. In addition, the chlorination leaching used converts the screened material (a small amount of elemental silver or silver compound) into silver chloride and enters the slag, and converts gold, platinum, palladium, rhodium and impurities into chloride liquid and enters the liquid phase. When a small amount of elemental silver conversion rate is low, it will also enter silver chloride and can directly enter the silver sinking; when a small amount of gold, platinum, palladium, rhodium and impurities cannot be converted into the liquid phase, they can be compensated by subsequent chlorination purification, and the chloride liquid is returned to the chlorination leaching for acid supplement, so that gold, platinum, palladium and rhodium are concentrated into the liquid phase, and returned to the existing gold separation or gold sinking process for centralized recovery of rare and precious metals. The problem of low dispersion recovery rate of platinum and palladium is solved. After chlorination purification of the chlorinated slag, high-quality silver powder is produced by reduction, which avoids the problem of poor quality of silver powder produced by silver chloride reduction in the existing process, thereby developing a silver electrolysis anode mud treatment method with simple process flow, low processing cost, high recovery rate of rare and precious metals, and more environmentally friendly.

[0014] Furthermore, the silver anode mud comprises, by mass percentage, 60-85% silver, 2-6% gold, 0.2-1.0% platinum, 0.5-1.0% palladium, 0.05-0.2% rhodium, 0.5-1.5% copper, 0.4-1.0% lead and 2.0-5.0% bismuth.

[0015] It is worth mentioning that the present invention uses a combination of physical screening and chemical dissolution and solid-liquid separation technology to quickly separate silver, lead, gold, platinum, palladium, rhodium and other rare and precious metals in silver anode mud, and meets the raw material requirements for returning to the silver and gold extraction systems respectively, thereby realizing the short-process treatment of high-silver silver anode mud and the comprehensive recovery of valuable metals, and has the advantages of short process, single reagent consumption, and low operating cost.

[0016] Furthermore, in the step (1), the ultrasonic vibrator is distributed at the bottom of the material, and the mesh size of the sieve used for screening is 0 to 100 meshes, and the liquid-to-solid ratio of alcohol to silver anode mud is 2-3:1.

[0017] It is worth noting that the cavitation effect of the ultrasonic vibration equipment at the bottom of the material can quickly make the elemental silver in the silver anode mud and the fine impurity particles or silver compounds adsorbed on the surface of the elemental silver vibrate by the cavitation effect of the ultrasonic wave, and the fine particles adsorbed on the surface of the elemental silver are easily detached in the alcohol solution and separated from the elemental silver particles. After screening in the alcohol medium, the elemental silver with large particles is retained in the screened material during the 0-100 mesh screening equipment process. The screened material obtained has a high silver content. The screened material obtained with too high a screening mesh number has a low silver content and does not use direct silver refining; the screened material obtained with too small a screening mesh number has a high silver content, but the process silver direct yield is low. Screening in the alcohol medium, fine particles (impurities or fine elemental silver) or silver compounds easily enter the mixed solution of the screened material and alcohol. During the screening process, the fine particles or silver compounds will not react chemically with the alcohol or have a sticky phenomenon, which is convenient for the subsequent liquid-solid separation to be thorough and the operation.

[0018] Furthermore, in step (2), the oxidant is one or two of sodium chlorate, hydrogen peroxide, and hypochlorous acid, the hydrochloric acid concentration is 3-5 mol / L, the solid-liquid ratio of chlorination leaching is 4:1, the reaction time is 3-4 hours, and the endpoint pH potential is greater than 1200 mV.

[0019] It is worth noting that through chlorination leaching, fine particles (impurity lead, bismuth, copper or fine elemental silver) react with hydrochloric acid under the action of an oxidant with an oxidation potential of 1200mv, so that the gold, copper, platinum, palladium, lead, bismuth and other elements in the material are respectively converted into aqueous chloride solutions of chloroauric acid, cuprous chloride, chloroplatinic acid, chloropalladic acid, lead chloride and bismuth chloride, while the silver element or silver compound with a particle size of 0-100 mesh can be easily reacted and converted into silver chloride slag, thereby realizing the separation of silver from other metals; after cooling, the lead chloride is supersaturated and crystallized and separated from the aqueous solution of gold, platinum, palladium and rhodium.

[0020] Furthermore, in the step (4), the concentration of hydrochloric acid used in the chlorination purification is 3-5 mol / L, the reaction temperature is 80-85° C., the reaction time is 1-3 hours, and the aging time is 2-5 hours.

[0021] It is worth noting that the concentration of hydrochloric acid used in chlorination purification is 3-5 mol / L, which further allows the impurity metals in the silver chloride slag to be more thoroughly converted into a chloride aqueous solution and separated from the silver chloride. At the same time, after the reaction is completed, the grains of the silver chloride slag can be grown through aging for 2-5 hours, avoiding the adsorption and entrainment of impurity ions by silver chloride during the liquid-solid separation process, meeting the quality of silver chloride to meet the downstream silver refining raw material requirements, shortening the silver extraction process, and reducing the loss of silver in the process.

[0022] Furthermore, the chlorinated liquid 2 obtained by filtration after chlorination purification in step (4) is returned to step (2) for chlorination leaching and acid replenishment.

[0023] That is, the present invention returns the chlorinated aqueous solution and free hydrochloric acid of gold, platinum, palladium, rhodium and impurities remaining in the chlorinated slag to step (2) through step (4), and can make comprehensive use of the hydrochloric acid in the chlorinated solution, which is convenient for controlling the hydrochloric acid concentration in step (2). At the same time, the gold, platinum, palladium, rhodium in the chlorinated solution can be returned to step (2) for recovery, thereby improving the recovery efficiency of precious metals and the removal rate of impurities.

[0024] Compared with the prior art, the present invention uses ultrasonic vibration-screening under an alcohol medium to quickly achieve graded screening of the granular elemental silver in the silver anode mud and the fine impurity particles or silver compounds adsorbed on the surface of the elemental silver, and recovers them separately. The elemental silver particles on the screen directly react with the process to process the silver anode plate, reducing the recovery rate loss caused by the return of this part of the silver. After the solid-liquid separation of the screened material, the liquid screening agent can be recycled, and the filter residue is leached by chlorination to allow the rare and precious metals such as gold, platinum, palladium, and rhodium contained in the material to enter the liquid phase. Its components meet the conditions of directly returning to the gold precipitation or gold separation and acid supplementation, so that all the rare and precious metals are enriched and enter the gold extraction process for comprehensive recovery. The gold extraction process is an existing conventional technical process. The whole process is short, simple to operate, and friendly to the working environment. At the same time, the valuable elements such as silver, gold, platinum, palladium, and rhodium in the silver anode mud are enriched and recovered, and the recovery rate is high. It is suitable for simple grafting in the existing anode mud treatment process to achieve recycling and avoid the loss of rare and precious metals in the treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0026] Figure 1 The present invention is a process flow chart of the short-process treatment method of silver electrolysis silver anode mud. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0029] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0030] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0031] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present application.

[0032] The present invention belongs to the technical field of hydrometallurgy of precious metals in nonferrous metallurgy, and specifically relates to a short-process treatment method for silver electrolysis silver anode mud, comprising adding an alcohol medium to the silver anode mud for ultrasonic vibration, dispersing the single substance and compound present in the silver anode, performing solid-liquid separation on the screen to obtain filter residue and filtrate, and returning the filtrate for vibration dispersion; and casting the silver anode plate by annealing on the screen. The obtained filter residue is subjected to chlorination leaching to convert rare and precious metal elements such as gold, platinum, palladium, and rhodium into chlorinated liquid of a chlorinated aqueous solution, and the single silver and its silver compound in the filter residue are converted into chlorinated residue of silver chloride. The chlorinated liquid is returned to the separation or precipitation of gold in the gold extraction process to obtain a coarse gold powder rich in platinum, palladium, and rhodium, which is used for refining to obtain a gold ingot; the chlorinated residue is directly returned to the reduction or separation of silver in the silver extraction process to obtain a high-quality coarse silver powder for electrolysis. The present invention has a simple process and a short process, and is suitable for simple grafting in the existing anode mud treatment process to achieve recycling and avoid the loss of rare and precious metals in the treatment process.

[0033] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0034] Example 1

[0035] A short-process treatment method for silver electrolysis silver anode mud:

[0036] (1) 1 kg of silver anode mud is taken, and alcohol is added to the silver anode mud for slurrying. The amount of alcohol added is 2 L. A 50-mesh sieve is used for sieving to obtain an oversize material with larger particles and an undersize material with more uniform particles. The oversize material weighs 450 g, and the weight percentage of silver content by chemical analysis is 95%. The oversize material is directly mixed with 2000 kg of coarse silver powder to cast a silver anode plate. The silver content is 99.3% when analyzed by direct reading spectrometer.

[0037] Table 1 Composition of silver anode mud in step (1)

[0038] element Ag Au Cu Pb Bi Pd Pt content 72.2％ 3.54％ 0.55％ 0.44％ 2.1％ 0.51％ 0.35％

[0039] (2) The undersize obtained in step (1) is subjected to solid-liquid separation to obtain a filter residue containing 53.5% silver (weight after drying is 540 g) and a filtered liquid.

[0040] (3) adding 3 mol / L hydrochloric acid and 40 g sodium chlorate to the residue obtained in step (2) at a liquid-to-solid ratio of 4:1, heating to 80-85° C., stirring and leaching for 3.5 hours, aging for 4 hours after the reaction, and performing liquid-solid separation to obtain silver chloride and chlorinated solution. The silver chloride is dried and weighed to 388 g, and the silver content is 74.2% by chemical titration. The silver chloride is sent to a silver extraction system and reduced with hydrazine hydrate to obtain a crude silver powder, which is tested by direct reading spectrometer and found to contain 99.95% silver.

[0041] (4) 3950 mL of the chlorinated solution obtained in step (3) is returned to the gold extraction process to produce 233 g of dry basis of crude gold powder, which is detected by titration method and contains 15.01% gold, 2.10% palladium and 1.48% platinum; the crude gold powder is directly returned to the gold refining system.

[0042] Example 2

[0043] A short-process treatment method for silver electrolysis silver anode mud:

[0044] (1) 10 kg of silver anode mud is taken, alcohol is added to the silver anode mud for slurrying, the amount of alcohol added is 25 L, and 80 mesh sieve is used for sieving to obtain an oversize material with larger particles and an undersize material with more uniform particles; the oversize material is weighed to have a mass of 5150 g, and the mass percentage of silver content by chemical analysis is 91%. The oversize material is directly mixed with 2000 kg of coarse silver powder to cast a silver anode plate, and the silver content is 99.1% by direct reading spectrometer analysis.

[0045] (2) subjecting the undersize obtained in step (1) to solid-liquid separation to obtain a filter residue containing 52.2% silver (weight after drying: 4850 g) and a filtered liquid;

[0046] (3) adding 3 mol / L hydrochloric acid and 440 g sodium chlorate to the residue obtained in step (2) at a liquid-to-solid ratio of 4:1, heating to 80-85° C., stirring and leaching for 3.5 hours, aging for 4 hours after the reaction, and performing liquid-solid separation to obtain silver chloride and chlorinated solution. The silver chloride is dried and weighed to 3320 g, and the silver content is 74.5% by chemical titration. The silver chloride is sent to a silver extraction system and reduced with hydrazine hydrate to obtain a crude silver powder, which is tested by direct reading spectrometer and found to contain 99.95% silver.

[0047] (4) 5650L of the chlorinated liquid obtained in step (3) is returned to the coarse gold powder for chlorination and gold separation, and rare and precious metal elements such as gold, platinum, palladium and rhodium in the chlorinated liquid are comprehensively recovered.

[0048] Example 3

[0049] A short-process treatment method for silver electrolysis silver anode mud:

[0050] Take 15kg of silver anode mud, add alcohol to the silver anode mud for slurrying, the amount of alcohol added is 30L, use a 100-mesh sieve to screen, and obtain an oversize material with larger particles and an undersize material with more uniform particles; the oversize material weighs 8.6kg, and the mass percentage of silver determined by chemical method is 88%. It is directly mixed with 2000kg of coarse silver powder to cast silver anode plates, and the direct reading spectrometer determines that the silver content is 99.1%.

[0051] The slurry of the undersize was filtered to obtain a filter residue containing 50.9% silver and 6.4kg dry weight. 3mol / L hydrochloric acid and 550g sodium chlorate were added, with a liquid-solid ratio of 4:1, and the temperature was raised to 80-85°C, stirred and leached for 3.5 hours. After the reaction was completed, the mixture was aged for 4 hours, and liquid-solid separation was performed to obtain 4.3kg silver chloride, which contained 74.5% silver by chemical titration. The silver chloride was dissolved in a solution of 220g / L sodium sulfite, and then 3.5kg formaldehyde was added for reduction to obtain a coarse silver powder containing 99.5% silver, which was used as a raw material for electrolytic silver.

[0052] Therefore, the present invention uses the physical method of alcohol-screening to simply sort out the granular elemental silver in the silver anode mud, quickly return it to the silver electrolysis system, and reduce the smelting turnover of silver. Fine-grained silver and its silver compounds are recycled through hydrochloric acid and oxidants to convert silver into a slag phase of silver chloride, and the aqueous solution of chlorides converted from rare and precious metals such as gold, platinum, palladium, and rhodium and impurities such as lead and bismuth enters the liquid phase, thereby separating them from silver. The obtained silver chloride is returned to the silver crude refining system after chlorination purification, and the aqueous chloride solution is returned to the gold crude refining system to recover rare and precious metals. The overall process flow of this method is short and can be used as a separate treatment of silver anode mud or grafted onto a gold and silver hydrometallurgical process. It is particularly suitable for a silver electrolysis anode mud treatment scheme based on a copper anode mud treatment process.

[0053] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A short-process treatment method for silver electrolysis silver anode mud, characterized in that: The specific steps include: (1) Ultrasonic vibration dispersion-screening treatment: After adding alcohol medium to the silver anode mud, ultrasonic vibration is performed to disperse the elements and compounds present in the silver anode; after vibrating for 10 to 50 minutes, the slurry is screened; the underscreen is subjected to solid-liquid separation to obtain filter residue and filtrate, and the filtrate is returned to the vibration dispersion; the overscreen is annealed to melt and cast the silver anode plate; (2) Chlorination leaching: adding hydrochloric acid and an oxidant to the filter residue obtained in step (1), heating and stirring to leach, and separating the solid and the liquid to obtain a chlorinated solution 1 and chlorinated residue; (3) returning the chlorinated solution 1 obtained in step (2) to the copper anode mud chlorination gold separation or gold precipitation process to recover rare and precious metals such as gold, platinum, palladium and rhodium; (4) The chlorinated slag obtained in step (2) is purified by chlorination to remove impurities, and then returned to the reduction and silver precipitation section of the silver extraction process to obtain crude silver powder, which enters the next refining stage.

2. The method according to claim 1, characterized in that Measured in percentage by mass, the silver anode mud comprises: 60-85% silver, 2-6% gold, 0.2-1.0% platinum, 0.5-1.0% palladium, 0.05-0.2% rhodium, 0.5-1.5% copper, 0.4-1.0% lead and 2.0-5.0% bismuth.

3. The method according to claim 1, characterized in that In the step (1), the ultrasonic vibrator is distributed at the bottom of the material, and the mesh size of the sieve used for screening is 0 to 100 meshes, and the liquid-to-solid ratio of alcohol to silver anode mud is 2-3:

1.

4. The method according to claim 1, characterized in that: In the step (2), the oxidant is one or two of sodium chlorate, hydrogen peroxide, and hypochlorous acid, the hydrochloric acid concentration is 3-5 mol / L, the solid-liquid ratio of chlorination leaching is 4:1, the reaction time is 3-4 hours, and the endpoint pH potential is greater than 1200 mV.

5. The method according to claim 1, characterized in that In the step (4), the concentration of hydrochloric acid used for chlorination purification is 3-5 mol / L, the reaction temperature is 80-85° C., the reaction time is 1-3 hours, and the aging time is 2-5 hours.

6. The method according to claim 5, characterized in that The chlorinated liquid 2 obtained by filtration after chlorination purification in step (4) is returned to step (2) for chlorination leaching and acid replenishment.

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