Process for treating high-chlorine materials in precious metal smelting

Abstract

The application discloses a treatment process of high-chlorine material in precious metal smelting. The process mainly comprises four process stages: (1) concentration stage; (2) evaporation separation stage; (3) precious metal recovery stage; and (4) circulation stage. In the precious metal recovery process, a physical separation method is introduced to separate chlorine and precious metal ions in the material, so that the problems of large chemical agent consumption and difficult treatment of waste water under the conditions of high-concentration chlorine ions and acidity are overcome. The process not only effectively treats the waste water and recovers harmful chlorine into reusable hydrochloric acid, but also recovers valuable elements with very low concentration or even difficult to detect, obtains precious slag with high grade and easy to recover, and basically does not cause loss of precious metals. Compared with the process using adsorbents such as activated carbon and resin, the process index is more stable, and the precious metal recovery is more simple.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of non-ferrous and precious metal smelting, and particularly relates to a treatment process for high-chlorine materials in precious metal smelting. BACKGROUND

[0002] The chlorine-containing materials include both solid and liquid, mainly aiming at various waste liquids and waste residues with soluble chlorine salts as main components, and similar intermediate materials can also be applicable. In the field of non-ferrous smelting, chlorine, sodium chloride, perchloric acid, sodium hypochlorite, sodium chlorate and other chlorine-containing reagents are widely used in industrial production, and a large amount of chlorine-containing materials need to be treated during the production. Since the non-ferrous industry usually involves a large number of limited emission elements, the composition of such materials is often complex, and the concentration of chloride ions as a strong complexing agent can greatly increase the difficulty of wastewater treatment, and it is difficult to meet the discharge indicators.

[0003] At present, the amount of such waste liquid and waste residue is generally small, but due to the characteristics of the coexistence of multiple elements in the non-ferrous industry, in recent years, with the development of science and technology, the refining technology has also made great progress. When multiple elements are comprehensively recovered, the process is often complex, resulting in a large number of types of wastewater and residue, and large differences in composition. Common methods for treating chlorine-containing wastewater, such as ion exchange, ultrafiltration, reverse osmosis, electrolysis, and electrodialysis, are difficult to treat all types of wastewater at the same time, which severely limits their application. Liquid is usually recovered by adsorption, sulfuration and other methods to recover trace amounts of valuable elements, and then treated as ordinary industrial wastewater or discharged, for example, the concentration of chloride ions in the waste liquid produced by the chlorination leaching gold process can reach 100 g / L, and often contains a high concentration of salt and trace amounts of Au, Ag, Pt, Pd and other precious metal elements. Due to the high ion concentration, saturated active site adsorption, and difficulty in analysis and detection, the treatment indicators are often difficult to control, and the recovery of precious metals adsorbed on activated carbon also has high technical difficulty, and the residual precious metal resources in the adsorbed liquid are also wasted. The solid generally contains valuable elements and is difficult to be treated as ordinary solid waste, and can only be designed with special methods, but similar to liquid, it also has the characteristics of "small amount", "many types" and "complex composition", and is usually treated by a reverse system, and the long-term circulation cannot avoid the accumulation of harmful elements.

[0004] Traditional water treatment process generally uses lime or quicklime as an adjusting agent, and most valuable elements are generally settled in the slag during the treatment process, causing resource waste. Since chloride ions are difficult to enter the slag, the treated water quality has problems such as high heavy metal, high hardness, high salinity and the like, which are difficult to solve, and reuse will cause a series of problems such as equipment corrosion, valuable metal dissolution, equipment and pipeline scaling and the like. Such influences are often ignored due to the difficulty in being reflected in a short period of time, thereby increasing the production cost in an invisible manner. Traditional evaporation process is rarely used due to high cost, and research is mainly aimed at relatively pure hydrochloric acid wastewater, mainly through the addition of magnesium chloride to destroy the azeotropic composition of hydrochloric acid to recover high-concentration hydrochloric acid. The particularity of non-ferrous industry wastewater is difficult to directly apply. SUMMARY

[0005] The purpose of the present application is to provide a treatment process for high-chlorine materials in precious metal smelting, which can cooperatively treat various chlorine-containing materials, uses evaporation process to recover and utilize chlorine as hydrochloric acid, and finally recovers low-content precious metals in the materials in solid form after enrichment. The process has excellent effect on recycling low-concentration high-value precious metal resources.

[0006] The chlorine-containing material is a liquid or solid in which chlorine mainly exists in the form of-1 valence or mixed-1 valence after treatment.

[0007] To achieve the above-mentioned purpose, as shown in the drawings, the present application adopts the following technical solutions: Figure 1

[0008] The present process mainly includes four process stages: (1) concentration stage; (2) evaporation separation stage; (3) precious metal recovery stage; and (4) circulation stage.

[0009] (1) Concentration stage

[0010] The purpose of this stage is to reduce the low-concentration liquid entering the evaporation separation stage without affecting the recovery of precious metals, thereby reducing the amount of liquid to be evaporated, reducing the treatment cost and improving the obtained hydrochloric acid concentration, and having no effect on the subsequent recovery of precious metals. If the total soluble chlorine of the mixed liquid of the chlorine-containing material to be treated is above 100 g / L (chloride ions can be better volatilized above this concentration), then this stage can be skipped. If the total soluble chlorine of the mixed liquid of the chlorine-containing material to be treated is less than 100 g / L, or even if the total soluble chlorine of the mixed liquid of the chlorine-containing material to be treated is above 100 g / L, the following operations are performed on the chlorine-containing liquid with a chloride ion concentration below 100 g / L:

[0011] a. The chlorine-containing liquid with a chloride ion concentration below 100 g / L is sorted according to the acidity (the acidity in this application refers to the concentration of hydrochloric acid), and one or several with lower acidity is used as chlorine-containing liquid A, and the remaining chlorine-containing material is used as chlorine-containing material B; ​

[0012] b. Separation and enrichment of chloride ions in the chlorine-containing liquid A to obtain enriched liquid C and dechlorinated liquid D;

[0013] Since the noble metal is generally in the form of chloride complex ions in the chlorine-containing liquid, it will enter the enriched liquid C together with chlorine during the enrichment process. The dechlorinated liquid D can be treated as ordinary wastewater, and the concentration endpoint can be reasonably selected according to different requirements for the dechlorinated liquid, which has no effect on the subsequent process.

[0014] (2) Evaporation separation stage

[0015] This stage is the key stage of the present application. First, the chlorine-containing material B, the enriched liquid C, and the circulating liquid H are sent into the evaporation crystallization device for mixing. Then, according to the amount and quality of noble metal to be recovered in the mixed liquid, the additive E is added. Since the concentration of noble metal in the wastewater is usually very low, the detection deviation is usually large. Therefore, the amount of additive added is generally not more than the theoretical required amount, in order to prevent waste of additive and affect the quality of the recovered material. It is recommended that the amount of additive added is 0.1-0.9 times the theoretical required amount, and the amount of additive added is adjusted according to the change trend of the concentration of noble metal to be recovered in the subsequent evaporation residue.

[0016] If the acid / chlorine molar ratio after mixing is less than 1, the additive F is added, otherwise it is not necessary. The higher the acid / chlorine molar ratio, the more conducive to reducing the concentration of chloride ions in the evaporation residue. However, too high acid / chlorine molar ratio will make hydrochloric acid volatilize in the form of HCl gas instead of in the form of azeotrope. Therefore, the acid / chlorine molar ratio is generally controlled at 1-3, and more preferably, the acid / chlorine molar ratio is 1-2.

[0017] The mixed liquid is heated and evaporated. Most of the chloride ions volatilize in the form of hydrochloric acid vapor, and hydrochloric acid is obtained after condensation. The remaining non-volatile substances are further concentrated and enriched in this process.

[0018] (3) Noble metal recovery stage

[0019] If the treated material contains selenium, part of it may enter the gas phase with the hydrochloric acid vapor, and finally be recovered together with the condensed hydrochloric acid. Liquid-solid separation of the hydrochloric acid can obtain crude selenium solid. After the chlorine-containing material is concentrated and enriched, the concentration of each element is increased. Since the concentration of chloride ions is reduced, the noble metal complexed by chloride ions is released. Even at a very low concentration, it can react with the additive E in the solution under the heat environment of evaporation, and co-precipitate with the soluble salt to form a solid-containing residue after the solubility is exceeded. The obtained residue is separated by sedimentation to obtain supernatant and noble metal slurry. The noble metal slurry is centrifuged and separated. The filtrate is combined with the supernatant. The solid layer containing salt crystals is added to the dechlorinated liquid D, stirred and dissolved, and then filtered to obtain noble residue and concentrated salt liquid.

[0020] (4) Circulation stage

[0021] The circulation stage is the treatment and recycling of the supernatant and concentrated salt liquid obtained in the noble residue treatment stage.

[0022] Concentrated salt liquid circulation: The concentrated salt liquid generally does not contain harmful elements, and can be directly treated or used as a solvent for dissolving salt crystals. When a certain concentration is reached, the concentrated salt liquid is cooled and crystallized, and the salt crystals are separated out. The crystallization mother liquor can continue to be used as a solvent for circulation. If the chloride ion content is high, the crystallization mother liquor can also be treated as a chloride-containing waste liquid. When the chloride ion concentration in the crystallization mother liquor reaches 100 g / L or above, the crystallization mother liquor can be combined with the supernatant for treatment.

[0023] Supernatant circulation: When the content of noble metal elements in the wastewater is low, it may not be possible to reach the precipitation concentration in a single treatment, and the noble metal elements may remain in the residual liquid. Therefore, multiple cycles of enrichment may be required. Even if the noble metal elements are precipitated, the residual liquid will usually contain a certain concentration of chloride. Therefore, the supernatant obtained in the noble residue treatment stage still contains unprecipitated noble metal elements and other valuable elements that can be recovered. Directly opening the circuit not only wastes resources but also reduces the chloride recovery rate. If the supernatant is recycled, not only can the valuable elements be recovered to the maximum extent, but also the subsequent chloride ion volatilization and precipitation can be facilitated. Due to the buffering effect of the ions in the circulating liquid, the addition amount of the reagents can be relaxed to a certain extent, reducing the operation difficulty. During the circulation process, some valuable elements that were difficult to recover in the previous stages or harmful elements that affect the volatilization of chloride ions may accumulate. Therefore, the supernatant needs to be purified to prevent the system from being affected during the circulation process. Based on the amount and type of impurities brought in by the chloride-containing material being treated, a portion or all of the supernatant is separated and added with reagent G for purification to obtain circulating liquid H to maintain the indicators in the evaporation separation stage within a reasonable range. If the amount of impurities brought in is small and has little effect on the system, the supernatant can be recycled for a certain number of times before being purified. The minimum amount of reagent G added is the theoretical reaction amount required for the difference between the impurities in the supernatant and the circulating liquid added in stage (2). However, the maximum amount of reagent G added should not exceed the amount required for the theoretical reaction of the impurities in the supernatant. It is recommended that the actual amount of reagent G added should not exceed 0.8 times the maximum amount to prevent the return of excessive purification agents to the system, which may cause the grade of the noble residue to decrease or even make the separation difficult. This process may produce purification residue containing valuable elements, which can be recovered as a concentrate.

[0024] Further, in step (1), the noble metal in the chloride-containing material is one or more of Au, Ag, Se, Cu, Te, Pt, Pd, and Rh.

[0025] Further, in step (1), the separation and enrichment of chloride ions in the chloride-containing liquid A refers to the use of one or more of conventional evaporation concentration, ion exchange, and membrane separation to separate and enrich the chloride ions in the chloride-containing liquid A.

[0026] Further, in step (2), the evaporation crystallization device includes but is not limited to one or a combination of OSLO type crystallizer, DTB type crystallizer, ordinary evaporator, reaction kettle, and related improved types.

[0027] Further, in step (2), the reagent E includes but is not limited to one or more of sulfurous acid, sodium chloride, sodium thiosulfate, sodium sulfite, metal elements, hydrazine hydrate and other reducing agents or salts, and mainly functions to react with the noble metal ions to be recovered to form a solid and precipitate from the solution.

[0028] Further, in step (2), the reagent F includes but is not limited to sulfuric acid, phosphoric acid, hydrochloric acid, hydrobromic acid, nitric acid, sulfurous acid and other acids that can provide H + .

[0029] Further, in step (4), the reagent G includes but is not limited to a mixture of one or more of calcium carbonate, calcium oxide, sodium hydroxide, magnesium oxide and sodium sulfide.

[0030] The acid / chlorine molar ratio in the present application refers to the molar ratio of hydrochloric acid and chloride ions.

[0031] The innovation of the present process is that, in the process of recovering noble metals, a physical separation method is introduced to separate chlorine and noble metal ions in the material, which overcomes the problems of large amount of reagent and difficult treatment of waste water under the conditions of high concentration of chloride ions and acidity. The process not only effectively treats the waste water and recovers the harmful chlorine into reusable hydrochloric acid, but also recovers valuable elements with very low concentration or even undetectable concentration, and obtains noble residue with high grade and easy to recover, and the loss of noble metal is basically avoided. Compared with the process using adsorbents such as activated carbon and resin, the process indicators are more stable, and the recovery of noble metal is more simple.

[0032] The beneficial effects of the present application are that: the present process simultaneously comprehensively treats a plurality of chlorine-containing materials, the process flow is simple and easy to implement, the recovery rate is high, and the selectivity of the material is poor. The present application not only overcomes the shortcomings of the prior art, but also effectively treats the liquid, even the solid material, especially the difficult-to-treat material containing controlled components, and does not produce new waste liquid, which is economic and environmentally friendly. The present application has good adaptability and can treat low-concentration noble metal-containing chlorine materials, recover hydrochloric acid, and enrich and recover noble metals therein; it is especially suitable for the separation and recovery of difficult-to-dissolve chlorine-containing compounds such as silver chloride, and good results can be obtained even at very low concentrations. In addition, the present application can also be used alone to recover chlorine BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is the process flow diagram of the present application. DETAILED DESCRIPTION

[0034] The technical solutions of the present application are further described in detail below in combination with specific embodiments, but the protection scope of the present application is not limited thereto.

[0035] Example 1:

[0036] There are 1600 mL of chlorine-containing liquid 1#, 3200 mL of chlorine-containing liquid 2#, and 400 g of solid chlorine-containing substance 3# with a mass fraction of about 90% NaCl to be treated. The chlorine-containing liquid 1# contains a higher concentration of Ag, which is intended to be recovered. The material is treated in four batches. The process is as follows:

[0037] (1) Concentration stage

[0038] The concentration of chloride ions after mixing the three chlorine-containing materials is about 159 g / L, which is greater than 100 g / L, so no concentration is needed. However, there are still liquids with a chloride ion concentration less than 100 g / L, and it is intended to obtain a higher concentration of hydrochloric acid, so concentration is carried out. The chlorine-containing liquid 1# has a chloride ion concentration less than 100 g / L and the lowest acidity. 400 mL of chlorine-containing liquid 1# is evaporated and concentrated to about half the volume. The evaporation gas is condensed to recover dechlorinated liquid with a chloride ion concentration of only about 0.2 g / L, and the enriched liquid that is not evaporated. The relevant results are shown in the table below.

[0039]

[0040] Note: The unit in Ag liquid is g / m 3 The remaining units are g / L.

[0041] (2) Evaporation separation stage

[0042] The enriched liquid is mixed with 800 mL of chlorine-containing liquid 2#, 100 g of chlorine-containing substance 3#, and the returned circulating liquid in a common evaporator. Since the acid (hydrochloric acid) / chlorine molar ratio is about 1.04, which is greater than 1, no acid is added. Ag can form AgCl precipitate with chloride ions, so no reagent is needed. Se mainly exists in the form of selenite, so a reducing agent is needed to recover Se. Sodium sulfite is added here, with a theoretical addition amount of about 0.5 g. Due to the low concentration, to prevent detection errors and other factors from affecting the addition amount, SO2 is generated, which affects the quality of hydrochloric acid. Here, 0.6 times the amount is added, only 0.3 g. If the concentration increases during the subsequent circulation process, the addition amount will be gradually increased. Then, heating distillation is carried out, and the residual liquid volume is controlled at about 400 mL. The steam is condensed to obtain slightly red hydrochloric acid. After filtration, red amorphous selenium and clear hydrochloric acid are obtained.

[0043] (3) Precious metal recovery stage

[0044] The supernatant was separated from the residue obtained in step (2) to obtain a noble metal slurry, and there was a clear boundary layer at the bottom of the noble metal slurry. The slurry was further centrifuged, and the liquid was filtered to obtain a crystal residue. The residue was separated into two parts in a ratio of about 4:1 from top to bottom (the boundary layer was slightly closer to the top). The upper part was an anhydrous sodium sulfate layer, and the lower part was a noble metal layer. The noble metal layer was dissolved in a dechlorination solution at about 30°C, and then filtered to obtain a grayish white silver chloride with a content of about 2wt%, and a sodium sulfate solution.

[0045] (4) Recycling stage

[0046] The sodium sulfate solution obtained in step (3) was about 600mL and was crystallized at about 10°C. The crystallization mother liquor after filtering out the sodium sulfate crystals was used as a solvent for the subsequent noble metal layer treatment. The supernatant and the centrifuged liquid of step (3) were mixed, and about 10wt% sodium sulfide was added dropwise to remove Cu. The theoretical amount of addition was about 2mL. Due to the low concentration, to prevent detection errors and other influences, the amount of addition was excessive. The excess amount would produce harmful gas H2S. Here, about 1.5mL (about 0.75 times) was added. If the concentration increased during the subsequent recycling process, the amount of addition would be gradually increased. The black copper sulfide residue was filtered, and the filtrate was returned to the evaporation separation stage as a recycling liquid.

[0047] After repeating steps (1) to (4) to treat all the chlorine-containing materials, about 4400mL of hydrochloric acid, about 0.6g of red amorphous selenium, about 0.9g of black copper sulfide residue, about 1.9g of noble residue, and about 380mL of recycling liquid were obtained. The relevant results are shown in the table below.

[0048]

[0049] Note: The unit in the Ag liquid is g / m 3 The remaining units are g / L.

[0050] Example 2:

[0051] Two kinds of liquids, 100L of chlorine-containing liquid 4# and 200mL of a mixture of sulfuric acid and hydrochloric acid containing chlorine liquid 5#, needed to be treated. Chlorine-containing liquid 4# contained a higher concentration of Te, which was intended to be recovered. The process was as follows:

[0052] (1) Concentration stage

[0053] Chlorine-containing liquid 4# was in a large amount and had a very low concentration of chloride ions. After mixing, the chloride ions did not reach 100g / L. Therefore, concentration was carried out. First, a JK206 type (Shanghai Nankai Resin Co., Ltd.) strong basic styrene anion exchange resin was used for adsorption and desorption (1.3L of 5wt% NaOH solution was added for desorption). Then, 1.3L of concentrated liquid was obtained. After evaporation and concentration to 200mL, about 101L of dechlorination liquid containing basically no chlorine was obtained, and about 200mL of enrichment liquid was obtained, which mainly contained NaCl. The relevant results are shown in the table below.

[0054]

[0055] Note: each substance unit is g / L.

[0056] (2) Evaporation separation stage

[0057] The enriched liquid and chlorine-containing liquid 5# are treated twice. 100 mL of enriched liquid, 100 mL of chlorine-containing liquid 5#, and the returned circulating liquid are mixed together in a common evaporator. Sulfurous acid with a mass concentration of 5% is added. According to the Te concentration, about 40 mL is needed. Considering that chlorine-containing liquid 5# may itself bring in unreacted sulfurous acid, it is difficult to accurately detect. In order to improve the grade of tellurium products, prevent excessive reductants from producing too many impurities, and prevent unreacted reductants from affecting the quality of hydrochloric acid, only 5 mL is added here to prevent excessive addition. The Te concentration in the residual liquid is detected, and an appropriate amount of reductant is supplemented in the circulating stage. Since the acid / chlorine molar ratio is 0.8, which is less than 1, 15 mL of commercially available 98% concentrated sulfuric acid is added to make the acid / chlorine molar ratio about 1.2, and then heated and distilled. The residual liquid volume is controlled at about 50 mL, and the vapor is condensed to obtain hydrochloric acid.

[0058] (3) Precious metal recovery stage

[0059] The residual liquid obtained in stage (2) is settled and separated to obtain a precious metal slurry and a supernatant. The lower part of the precious metal slurry has no obvious stratification, and it is directly centrifuged to obtain a filtrate and a solid. The solid is dissolved and crystallized using dilute hydrochloric acid prepared with dechlorination liquid at about 30°C to obtain a sodium sulfate solution and a 99.5% grade tellurium (precious residue).

[0060] (4) Circulation stage

[0061] The supernatant and the centrifuged liquid from step (3) are mixed, and the remaining Te in the sodium sulfite reduction solution is slowly added until no black substance is produced. A total of 0.8 g is added here. Filtration is performed to obtain 95% crude tellurium. The filtrate, about 30 mL, is returned to the evaporation separation stage as a circulating liquid.

[0062] The sodium sulfate solution obtained in stage (3) is recycled for dissolution and crystallization.

[0063] The remaining enriched liquid and chlorine-containing liquid 5# are treated by repeating stages (2) to (4). A total of about 400 mL of hydrochloric acid, 1.2 g of refined tellurium (precious residue), about 100 mL of concentrated sodium sulfate solution, and 2.0 g of crude tellurium are obtained. The relevant results are as follows.

[0064]

[0065] Note: each substance unit is g / L.

[0066] The concentrated sodium sulfate solution is reduced to about 10°C to crystallize, and the crystallized sodium sulfate is filtered out. The crystallization mother liquor is recycled as the solvent.

[0067] Example 3:

[0068] Two kinds of liquid, 1L of chlorine-containing liquid 6# and 500mL of chlorine-containing liquid 7# need to be treated, wherein the chlorine-containing liquid 6# contains very low concentrations of noble metals Pt and Rh, and the original liquid is difficult to recover. The process is as follows:

[0069] (1) Concentration stage

[0070] After mixing the two kinds of liquid, the chloride ion concentration is about 112g / L, which is greater than 100g / L, but the chloride ion concentration of the larger volume of chlorine-containing liquid 6# is lower than 100g / L, and the acidity is not high, and the acid / chlorine molar ratio is only about 0.5. In order to improve the final hydrochloric acid concentration, 1L of chlorine-containing liquid 6# is evaporated and concentrated to a volume of about 400mL, and the evaporation gas is condensed and recovered to obtain a dechlorination liquid with a chloride ion concentration of about 1g / L. The relevant results are shown in the table below.

[0071]

[0072] Note: Pt, Rh unit is g / m 3 ， The rest is g / L.

[0073] (2) Evaporation separation stage

[0074] Since the acid / chlorine molar ratio of the mixed liquid is about 0.7, which is less than 1, 145mL of commercially available 98% sulfuric acid is added to increase the acid / chlorine molar ratio to about 1.8. The chlorine-containing liquid 6# contains a small amount of reagent sodium sulfite, which is not added separately here. The enriched liquid, chlorine-containing liquid 7# and returned circulating liquid are added to the ordinary evaporator for heating distillation, and the residual liquid volume is controlled at about 300mL. The vapor is condensed and recovered to obtain hydrochloric acid.

[0075] (3) Noble metal recovery stage

[0076] The residual liquid obtained in stage (2) is settled and separated to obtain a noble metal slurry and a supernatant. The noble metal slurry has no obvious stratification in the lower part, and is directly centrifuged to obtain a filtrate and a solid. The solid is slurried with a dechlorination liquid to dissolve the soluble crystals, and the filtrate and needle-shaped crystals are obtained by filtration.

[0077] (4) Circulation stage

[0078] The solution of about 60 mL obtained in the step (3) is reduced to about 10°C for crystallization, and the crystallization mother liquor of salt crystals is filtered out and recycled as a solvent for the noble metal layer treatment. The supernatant and the centrifugal separation liquid of about 280 mL of the step (3) are mixed, and since the impurities are less, the mixture can be directly returned. If the recycling times are more, the soluble silicate is accumulated (about 0.1 g / L is brought in the waste water), which causes the viscosity of the liquid to obviously increase. The CaO of the theoretical reaction amount of the silicate is added for purification treatment, which can remove part of the silicate affecting the viscosity of the liquid. Alternatively, part of the liquid can be separated each time for treatment to achieve the same effect. A small amount of purification residue and purification liquid are obtained by filtration. The main component of the purification residue is calcium sulfate, which can be recycled. The purification liquid is combined with the supernatant, and the whole is returned to the evaporation separation stage as the recycling liquid.

[0079] After the treatment of the steps (1)-(4), a total of 700 mL of hydrochloric acid and 4.5 g of precious residue are obtained. The main components of the precious residue are lead sulfate and calcium sulfate, and the total grade of rhodium and platinum is about 500 g / t. The relevant results are shown in the following table.

[0080]

[0081] Note: The units of each substance are g / L.

[0082] The above implementation cases are only used to illustrate the preferred embodiments of the present application, but the present application is not limited to the above embodiments. Any modification, equivalent replacement and improvement within the scope of knowledge possessed by those skilled in the art and within the spirit and principle of the present application should be considered as the protection scope of the present application.

Claims

1. A process for the treatment of precious metal smelting high-chlorine material, characterized in that, The method comprises the following steps: (1) Concentration stage If the total soluble chlorine of the mixed liquid of the chlorine-containing material to be treated is more than 100 g / L, the stage can be skipped. If the total soluble chlorine of the mixed liquid of the chlorine-containing material to be treated is less than 100 g / L or even if the total soluble chlorine of the mixed liquid of the chlorine-containing material to be treated is more than 100 g / L, the following operations are performed on the chlorine-containing liquid with a chlorine ion concentration less than 100 g / L: a. The chlorine-containing liquid with a chlorine ion concentration less than 100 g / L is sorted according to the acidity, and one or several of the liquids with lower acidity are taken as chlorine-containing liquid A, and the rest of the chlorine-containing material is taken as chlorine-containing material B, wherein the acidity refers to the concentration of hydrochloric acid; b. The chlorine ions in the chlorine-containing liquid A are separated and enriched to obtain enriched liquid C and dechlorination liquid D; The chlorine-containing material is a liquid or solid in which chlorine exists in the form of -1 valence or mixed treatment after being treated in the form of -1 valence; the noble metal in the chlorine-containing material is one or more of Au, Ag, Se, Cu, Te, Pt, Pd and Rh; (2) Evaporation separation stage The chlorine-containing material B, the enriched liquid C and the circulating liquid H are mixed in an evaporation crystallization device, and a reagent E is added in an amount not higher than the theoretical required amount according to the amount of noble metal to be recovered in the mixed liquid. If the acid / chlorine molar ratio of the mixture is less than 1, a reagent F is added to make the acid / chlorine molar ratio 1-3, otherwise no reagent F is added. The mixed liquid is heated and evaporated, and the steam is condensed to obtain hydrochloric acid; If the treated wastewater contains selenium, the hydrochloric acid is subjected to liquid-solid separation to obtain coarse selenium solid. The remaining non-volatile substances form a residual liquid at the bottom of the distillation device. The reagent E is one or more of sulfurous acid, sodium thiosulfate, sodium sulfite and hydrazine hydrate, and the addition amount is 0.1-0.9 times the theoretical required amount. The reagent F is a mixture of one or more of sulfuric acid, phosphoric acid, hydrobromic acid, nitric acid and sulfurous acid; (3) Noble metal recovery stage The residual liquid obtained in step (2) is subjected to sedimentation separation to obtain supernatant and noble metal slurry. The noble metal slurry is subjected to centrifugal separation, the filtrate is combined with the supernatant, and the solid layer containing salt crystals is added to the dechlorination liquid D for stirring and dissolution, and then filtered to obtain noble residue and concentrated salt liquid; (4) Circulation stage Concentrated salt liquid circulation: The concentrated salt liquid is used as a solvent for dissolving salt crystals, and when a certain concentration is reached, it is concentrated and cooled to crystallize, and the salt crystals are separated out. The crystallization mother liquor is continuously used as a solvent for circulation. When the chlorine ion concentration in the crystallization mother liquor reaches 100 g / L or more, it is combined with the supernatant for treatment. Supernatant circulation: A part or all of the obtained supernatant is added to a reagent G for purification to obtain qualified circulating liquid H which is returned to step (2). If the purification process produces a purification residue containing valuable elements, the purification residue can be used as a concentrate for recovery. The reagent G is a mixture of one or more of calcium carbonate, calcium oxide, sodium hydroxide, magnesium oxide and sodium sulfide.

2. The process for the treatment of precious metal smelting high-chloride materials according to claim 1, characterized in that, In step (1), the separation and enrichment of chlorine ions in the chlorine-containing liquid A refers to one or more of the conventional evaporation concentration, ion exchange and membrane separation methods.

3. The process for the treatment of precious metal smelting high-chloride materials according to claim 1, characterized in that, In step (2), the evaporation crystallization device is one or a combination of OSLO type crystallizer and DTB type crystallizer.

4. The process for the treatment of precious metal smelting high-chloride materials according to claim 1, characterized in that, In step (4), the minimum amount of medicament G added is the theoretical reaction amount required for the difference in impurities between the supernatant and the circulating liquid H added in step (2), and the maximum amount of medicament G added is 0.8 times the theoretical reaction amount required for the impurities in the supernatant.

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