Method for enriching and recovering copper and rhenium from rhenium-containing copper smelting dust

Abstract

The present application relates to a kind of methods for enriching and recovering copper and rhenium from rhenium-containing copper smelting dust: after rhenium-containing dust is added with an oxidizing agent, it is slurried with water, the slurry temperature is 25-80°C, and a slurry is obtained; the slurry is leached with ammonia water, the leaching temperature is 25-60°C, and the leaching time is 0.5-6h; after the leaching is completed, the solid-liquid separation is performed, and a leaching residue and a leaching solution are obtained; the leaching solution is subjected to freeze crystallization, and a freeze-crystallized product is obtained; the freeze-crystallized product is dried, and the moisture content of the dried product is 0.5-2%; the dried crystallized product is subjected to first closed thin-layer thermal decomposition roasting and second closed thin-layer thermal decomposition roasting, and the condensable components in the second pyrolysis gas are cooled to form rhenium oxide; the rhenium oxide is dissolved, extracted, back-extracted, and crystallized to obtain ammonium rhenate product. The method has the advantages of being more suitable for disposing of copper smelting dust with complex composition, unstable composition, large span of single-element content range, and low rhenium content limit, and the separation degree of valuable elements such as copper, arsenic, rhenium, silver, and lead is high.

Description

Technical Field

[0001] This invention belongs to the field of copper-rhenium recovery technology, specifically relating to a method for enriching and recovering copper-rhenium from rhenium-containing copper smelting dust. Background Technology

[0002] Rhenium (Re), a scarce strategic metallic element, is used in over 90% of the production of high-temperature superalloys and platinum-rhenium catalysts. Copper and molybdenum smelting flue dust and waste acid are the main secondary resources containing Re, and recovery technologies need to be developed according to the differences in raw materials. In the traditional copper smelting industry, rhenium is first enriched in dilute acid from smelting flue gas purification, and then further enriched and refined through chemical precipitation or non-chemical precipitation methods. Commonly used chemical precipitation methods include sulfide precipitation; commonly used non-chemical precipitation methods include resin adsorption-desorption; the key to deep rhenium refinement lies in achieving high-precision separation of Re from impurity elements.

[0003] Currently, the high-quality concentrate market is highly competitive and procurement is difficult. Furthermore, with the outbreak of local conflicts, geopolitical issues, and trade frictions worldwide, the prices of by-products such as precious metals and rare metals have risen, making their revenue a major source of profit for smelters. Major smelting enterprises are shifting their business strategies towards "reducing copper content and increasing rare and precious metal content," ushering in an era of handling complex concentrates. As the input raw materials become more complex, the composition of smelting flue gas also becomes increasingly complex. Smelting enterprises have had to adjust their flue gas dust collection and wet purification strategies to prevent impurities such as arsenic from entering the acid conversion and dry absorption processes. These strategies include, but are not limited to, stepped cooling, which causes rhenium enrichment to occur earlier in the dust collection process, rarely entering the wet purification process. This results in a large amount of rhenium-containing copper smelting dust, rendering the original method of recovering rhenium from purified waste acid ineffective.

[0004] The current mainstream process for treating rhenium-copper-containing flue dust involves acid leaching of the flue dust, solid-liquid separation, leachate purification, resin adsorption, and desorption to obtain crude ammonium rheniumate concentrate, followed by deep refining of the crude ammonium rheniumate concentrate. This method inevitably encounters the following problems: 1) During the acid leaching of flue gas, in addition to rhenium entering the liquid phase, copper, arsenic, nickel, zinc, and other elements also enter the liquid phase, leading to an increase in the total amount of soluble salts (such as sulfates, arsenic trioxide, and arsenic acid) in the leachate. These soluble salts are difficult to eliminate through physical methods (cryogenic crystallization and precision filtration) and chemical methods (displacement or precipitation), and can only be reduced to a limited extent. When the purified leachate enters the resin adsorption system, the flow rate difference within the resin will cause a throttling effect. That is, in the low flow rate region, soluble salts will precipitate from the liquid phase and become solids. The solid salts form a surface coating on the resin, preventing the resin from adsorbing them. Moreover, this phenomenon will gradually shift to the high flow rate region over time, causing the overall flow rate of the adsorption system to decrease, rendering the adsorption system ineffective. Although the resin surface can be restored through chemical or mechanical cleaning, it will still result in resin loss, increased costs, and a serious impact on operational efficiency. 2) While the resin system adsorbs rhenium, it also competes with impurities such as copper and arsenic for adsorption. Because the copper / rhenium and copper / arsenic concentrations are relatively high, the adsorption capacity and adsorption rate of impurities such as copper and arsenic will be higher, the adsorption-desorption frequency of the resin will be high, the consumption of desorbent will increase, and the copper and arsenic content in the crude ammonium perrylate concentrate will be high, which will prolong the process and increase the difficulty of deep rhenium extraction.

[0005] In view of this, this application was developed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a novel method for enriching and recovering copper and rhenium from copper smelting dust containing rhenium. The core of this method lies in using ammonia leaching instead of the original neutral or acidic leaching, maximizing the entry of valuable elements such as copper, arsenic, rhenium, and silver into the liquid phase. Then, a crystallization process is used to convert these valuable elements into solid salts. Finally, a staged roasting-crystallization process separates arsenic, copper, silver, and rhenium, followed by further refining to form the relevant products. The advantages of this method are that it is more suitable for handling copper smelting dust with complex and unstable compositions, a wide range of individual element contents, and low rhenium content limits, and it achieves a high degree of separation of valuable elements such as copper, arsenic, rhenium, silver, and lead.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for enriching and recovering copper and rhenium from rhenium-containing copper smelting dust, wherein the process is suitable for rhenium-containing dust with the following composition: rhenium 5-5000 g / t, copper 0.2-15%, arsenic 2-60%, lead 2-35%, sulfur (referring to sulfur in sulfides, not sulfur in sulfate form) 1-10%, and silver 5-500 g / t, comprising the following steps: 1) After adding an oxidant to the rhenium-containing flue dust, water is used to prepare the slurry at a temperature of 25-80℃ to obtain the prepared slurry. 2) The slurry is leached with ammonia water at a leaching temperature of 25-60℃ for 0.5-6 hours. After leaching, solid and liquid are separated to obtain leaching residue and leachate. 3) The leachate is subjected to freeze crystallization to obtain freeze crystals; 4) The frozen crystals are dried, and the dried material contains 0.5-2% water. 5) The dried crystals are subjected to a first closed thin-layer thermal decomposition roasting to obtain the first thermal decomposition residue; the first thermal decomposition temperature is controlled at 200-280℃, the decomposition time is 0.5-2h, and the material thickness is 10-50mm; the first thermal decomposition gas is subjected to induced cooling at a cooling temperature of 90-150℃ for 0.5-2h; the condensable components in the first thermal decomposition gas are cooled into arsenic trioxide particles; 6) The residue from the first thermal decomposition is subjected to a second closed-loop thin-layer thermal decomposition roasting to obtain the second thermal decomposition residue; the second thermal decomposition temperature is controlled at 300-380℃, the decomposition time is 0.5-1h, and the material thickness is 10-50mm; the second thermal decomposition gas is subjected to induced cooling at a cooling temperature of 50-130℃ for 0.5-1h, and the condensable components in the second thermal decomposition gas are cooled to rhenium oxides; 7) Rhenium oxide is dissolved, extracted, back-extracted and crystallized to obtain ammonium rheniumate. The residue from the second thermal decomposition (enriched with copper oxide, silver oxide, etc.) is dissolved by adding 8-20% sulfuric acid, and silver is precipitated by adding solid sodium chloride. The mixture is then filtered to separate copper sulfate solution and solid silver chloride. The copper sulfate solution is evaporated and crystallized to obtain anhydrous copper sulfate.

[0008] Specifically, in step 1), the oxidant is selected from oxygen, ozone, oxygen-enriched air, or hydrogen peroxide; when hydrogen peroxide is used, the mass of H2O2 should be 2.3-5.0 times the mass of sulfur element in sulfides in rhenium-containing dust; when oxygen, ozone, or oxygen-enriched air is used, the mass of O2 should be 2.0-5.0 times the mass of sulfur element in sulfides in rhenium-containing dust.

[0009] Furthermore, in step 1), the liquid-to-solid ratio during slurry preparation is 2.5-5 L: 1 kg.

[0010] Specifically, in step 2), the ammonia concentration is 10-28%, and the total mass of ammonia is controlled at 0.4-0.65 times the total mass of copper, arsenic, and rhenium.

[0011] Specifically, in step 3), the freezing temperature is -10~10℃ and the freezing time is 1-6h.

[0012] Specifically, in step 4), the drying temperature is 40-90℃.

[0013] Specifically, in step 7), the dissolution process involves using 2-4 mol / L sulfuric acid, with a liquid-to-solid ratio of 3-8 ml:1 g, a dissolution temperature of 60-85℃, and a time of 0.5-2 h.

[0014] Further, in step 7), the extraction is specifically as follows: the organic phase is extracted using a mixed solvent of N235-2-octanol-kerosene, with a volume ratio of N235-2-octanol-kerosene of 20:20:60, an extraction temperature of 20-30℃, and an extraction and phase separation time of 10-60 min.

[0015] Further, in step 7), the back-extraction-crystallization process is as follows: 3.5-6 mol / L ammonia water is used as the back-extraction agent, the back-extraction temperature is 20-40℃, and the back-extraction and phase separation time is 10-60 min; the back-extraction solution is concentrated at 80-95℃ under normal pressure to 100-200 g / L of rhenium, and the concentrated solution is cooled at -10~0℃ for 8-24 h to obtain wet ammonium rhenium crystals; the wet ammonium rhenium crystals are washed with 0.5-1 mol / L ammonia water and pure water until neutral, and dried at 60-80℃ for 0.5-3 h to obtain the ammonium rhenium product.

[0016] More preferably, the rhenium-containing flue dust contains: 5-5000 g / t of rhenium, 0.2-15% of copper, 2-60% of arsenic, 2-35% of lead, 1-10% of sulfur (referring to sulfur in sulfides, not sulfur in sulfate form), and 5-500 g / t of silver.

[0017] As a preferred technical solution, the above-mentioned method for enriching and recovering copper and rhenium from rhenium-containing copper smelting dust specifically includes the following steps: 1) After adding an oxidant to the rhenium-containing flue dust, water is used to prepare the slurry. The liquid-to-solid ratio (liquid volume to solid mass ratio) is 2.5-5 L: 1 kg, and the slurry preparation temperature is 25-80℃ to obtain the prepared slurry. Oxygen, ozone, oxygen-enriched air, or hydrogen peroxide can be used as the oxidant. When using hydrogen peroxide, the mass of H2O2 should be 2.3-5.0 times the mass of sulfur in the rhenium-containing flue dust. When using oxygen, ozone, or oxygen-enriched air, the mass of O2 should be 2.0-5.0 times the mass of sulfur in the rhenium-containing flue dust. 2) The slurry is leached with ammonia solution at a concentration of 10-28%, with the total mass of ammonia controlled at 0.4-0.65 times the total mass of copper, arsenic, and rhenium. The leaching temperature is 25-60℃, and the leaching time is 0.5-6 hours. After leaching, solid-liquid separation is performed, and the leaching residue is washed and the washing liquid is recycled. The leaching residue is rich in lead, bismuth, and antimony, which is used to recover lead, antimony, and bismuth through pyrometallurgical smelting. 3) Freeze the leachate to crystallize at a temperature of -10 to 10°C for 1 to 6 hours to obtain frozen crystals; the crystallized liquid and the washing liquid are reused in the leaching process. 4) Deep dehydration of the frozen crystals is achieved through low-temperature drying. The drying temperature is 40-90℃, and the moisture content of the dried material is 0.5-2%. 5) The dried crystals undergo a first closed-loop thin-layer thermal decomposition roasting to obtain the first thermal decomposition residue. The first thermal decomposition temperature is controlled at 200-280℃, the decomposition time is 0.5-2h, and the material thickness is 10-50mm. The first thermal decomposition gas is subjected to induced cooling at a temperature of 90-150℃ for 0.5-2h. The condensable components in the first thermal decomposition gas are cooled to high-quality arsenic trioxide particles; the non-condensable gas is absorbed by dilute ammonia water through circulation to obtain industrial-concentration ammonia water, which is reused in the leaching and ammonia preparation process. The first thermal decomposition residue mainly consists of enriched substances such as ammonium perlite, copper sulfate, copper oxide, and silver oxide. 6) The residue from the first thermal decomposition is subjected to a second closed-loop thin-layer thermal decomposition roasting to obtain a second thermal decomposition residue. The second thermal decomposition temperature is controlled at 300-380℃, the decomposition time is 0.5-1h, and the material thickness is 10-50mm. The second thermal decomposition gas is subjected to induced cooling at a cooling temperature of 50-130℃ for 0.5-1h. The condensable components in the second thermal decomposition gas are cooled to rhenium oxides; the non-condensable gases are absorbed by dilute ammonia water through circulation to obtain industrial-concentration ammonia water, which is reused in the leaching and ammonia preparation process. The second thermal decomposition residue mainly consists of copper oxide, silver oxide, and other enriched substances. 7) Rhenium oxide concentrate is purified by dissolution, extraction, back-extraction, and crystallization to obtain ammonium rheniumate. Dissolution uses 2-4 mol / L sulfuric acid at a liquid-to-solid ratio of L:S = 3-8:1 ml / g, at a temperature of 60-85℃, for 0.5-2 h. The organic phase is extracted using a mixed solvent of N235-2-octanol-kerosene, where N235 is trioctyldecyl tertiary amine as the main extractant, and 2-octanol and kerosene as diluents. The volume ratio of N235-2-octanol-kerosene is 20:20:60, the extraction phase ratio O / A = 1:1-2 (volume ratio), the extraction temperature is 20-30℃, and the extraction and phase separation time is 10-60 min. Back-extraction uses 3.5-6 mol / L ammonia water as the back-extraction agent, with a back-extraction ratio of O / A = 1.5-2.5:1 (volume ratio), a back-extraction temperature of 20-40℃, and a back-extraction and phase separation time of 10-60 min. The back-extraction solution is concentrated at 80-95℃ under normal pressure to a rhenium Re = 100-200 g / L; the concentrated solution is cooled at -10~0℃ for 8-24 h to obtain wet ammonium rhenium crystals; the wet ammonium rhenium crystals are washed with 0.5-1 mol / L ammonia water and pure water until neutral, and dried at 60-80℃ for 0.5-3 h to obtain the ammonium rhenium product.

[0018] 8) The residue from the second thermal decomposition (mainly enriched with copper oxide, silver oxide, etc.) is separated from silver and copper by acid dissolution-precipitation to obtain silver and copper-related products. The residue (enriched with copper oxide, silver oxide, etc.) is dissolved by adding 8-20% sulfuric acid, and silver is precipitated by adding solid sodium chloride. The mixture is then filtered to obtain a copper sulfate solution and solid silver chloride. The copper sulfate solution is evaporated and crystallized to obtain anhydrous copper sulfate. The solid silver chloride is slurried with water, and the pH is adjusted to 1-2 with hydrochloric acid. The acidic silver chloride slurry is replaced with 60-100 mesh iron powder. After replacement, the mixture is filtered to obtain crude silver powder. The crude silver powder is then treated with 15% hydrochloric acid to remove iron, filtered, washed with water, and dried to obtain elemental silver powder.

[0019] The process principle involved in the method of this invention is as follows.

[0020] 1. The rhenium phase in the flue dust is mainly rhenium heptaoxide, arsenic is mainly arsenic trioxide with a small amount of arsenic pentoxide, and silver and copper are mainly sulfates and oxides. Depending on the smelting conditions, a small amount of sulfides may be present. Sulfates are soluble in water; arsenic trioxide and a small amount of arsenic pentoxide are readily soluble in water to form oxyacids. The free hydrogen ions released by these oxyacids can accelerate the dissolution of rhenium, copper, and silver oxides and increase the solubility of copper and silver sulfates. Using an appropriate amount of oxidant to condition the slurry can oxidize the sulfides into more soluble oxides or sulfates. Therefore, under conditions where oxidant is used in conjunction with process water for slurry conditioning, rhenium, arsenic, copper, and silver mainly enter the liquid phase. Increasing the temperature is beneficial for accelerating the dissolution reaction.

[0021] Main reaction: As₂O₃ + 3H₂O = 2H₃AsO₃ As₂O₅ + 3H₂O = 2H₃AsO₄ Re₂O₇ + H₂O = 2HReO₄ CuO + 2H+ + =Cu 2+ +H2O Ag₂O + 2H⁺ + =2Ag + +H2O Re₂S₇ + 70H₂O₂ = 2ReO₄ - +7SO4 2- +70H2O+14H + As₂S₃ + ​​14H₂O₂ = 2H₃AsO₄ + 3SO₄ 2- +8H + +8H2O CuS + 4H₂O₂ = Cu 2+ +SO4 2- +2H + +2H2O Ag₂S + 4H₂O₂ = 2Ag+ +SO4 2- +2H + +2H2O 2. After oxidation and slurry preparation, the material is subjected to ammonia leaching. Arsenic acid, arsenite, and rhenium acid are converted into their corresponding ammonium salts, while silver and copper are converted into their corresponding complexes, further increasing their solubility. Meanwhile, lead, antimony, bismuth, and gold in the flue dust cannot be dissolved in the ammonia leaching system, thus ultimately achieving the separation of copper, silver, rhenium, and arsenic from lead, antimony, bismuth, and gold.

[0022] HReO4 + NH3·H2O = NH4ReO4 + H2O H3AsO4+3NH3·H2O=(NH4)3AsO4+3H2O H3AsO3+3NH3·H2O=(NH4)3AsO3+3H2O CuSO4+4NH3·H2O=[Cu(NH3)4]SO4+4H2O Ag2SO4+4NH3·H2O=[Ag(NH3)2]2SO4+4H2O 3. Water-soluble NH4ReO4, (NH4)3AsO4, (NH4)3AsO3, [Cu(NH3)4]SO4, and [Ag(NH3)2]2SO4 can form solids with extremely low water content under dehydration and low-temperature deep drying conditions.

[0023] 4. The crystallized solution still contains certain amounts of arsenic, copper, silver, and rhenium. The crystallized solution is recycled to the ammonia leaching process, which is beneficial for the enrichment of low-grade elements. For example, when the rhenium and silver grades in the flue dust are relatively low, the concentration in the ammonia leaching solution is also relatively low. They may not be able to crystallize during the crystallization process. Only when the concentration is accumulated to a certain level through cyclic leaching can they crystallize during the crystallization process.

[0024] 5. NH4ReO4, (NH4)3AsO4, (NH4)3AsO3, [Cu(NH3)4]SO4, and [Ag(NH3)2]2SO4 undergo decomposition reactions upon heating. The volatilization-sublimation properties of the products differ depending on the temperature range in which the decomposition occurs. Therefore, staged pyrolysis and condensation can yield different products, thus achieving the separation of rhenium, arsenic, copper, and silver.

[0025] The first stage achieves the separation of arsenic from rhenium, copper, and silver, as well as the recovery of ammonia. The key process points are controlling the thermal decomposition temperature at 200-280℃ and the thermal decomposition gas-induced cooling temperature at 90-150℃.

[0026] For (NH4)3AsO4, the following reaction occurs when heated to 200-280℃: 2(NH4)3AsO4( s)=As2O5+3H2O+6NH3( g As₂O₅ is easily reduced to As₂O₃ by NH₃, 5As₂O₅ + 6NH₃ = 5As₂O₃. g )+3N2( g )+9H2O( g ).

[0027] For (NH4)3AsO3, when heated to 200-280℃, the reaction 2(NH4)3AsO3( s )= As2O3( g )+3H2O( g )+6NH3( g ) When heated to 200-280℃, [Cu(NH3)4]SO4 and [Ag(NH3)2]2SO4 also decompose. [Cu(NH3)4]SO4( s )=CuSO4( s )+4NH3( g ) [Ag(NH3)2]2SO4( s )=Ag2SO4( s )+4NH3( g ) Through the above heating process, (NH4)3AsO4, (NH4)3AsO3, [Cu(NH3)4]SO4, and [Ag(NH3)2]2SO4 are completely decomposed, with all the arsenic decomposing as As2O3. g Ammonia enters the pyrolysis gas in the form of NH3 (NH4+). g The copper and silver are mainly in the form of copper sulfate and silver sulfate phases, while NH4ReO4 remains in solid form in the first roasting residue, thus achieving the separation of arsenic and ammonia from rhenium, copper, and silver.

[0028] When the pyrolysis gas is condensed at 90-150℃, As2O3 (…) is formed. g )= As2O3( s At this temperature, condensable arsenic trioxide is converted from gaseous to solid arsenic trioxide product. Non-condensable ammonia and a small amount of water vapor enter the ammonia recovery system, and are absorbed by dilute ammonia water to obtain industrial concentration ammonia water, which is then reused in the leaching and ammonia preparation process, thus realizing the separation of ammonia and arsenic.

[0029] The second stage achieves the separation of rhenium from copper and silver, as well as the recovery of ammonia. The key process points are controlling the thermal decomposition temperature at 300-380℃ and the thermal decomposition gas-induced cooling temperature at 50-130℃.

[0030] For NH4ReO4, when heated at 300-380℃, the reaction 2NH4ReO4( s =Re2O7( g )+2NH3( g )+H2O( g ) When heated to 300-380℃, CuSO4 and Ag2SO4 also decompose. 2CuSO4( s )=2CuO( s )+2SO2( g )+O2( g ) 2Ag2SO4( s )=2Ag2O( s )+ 2SO2( g )+O2( g ) Through the above heating process, NH4ReO4 is completely decomposed, with all rhenium decomposing as Re2O7 (…). g Ammonia enters the pyrolysis gas in the form of NH3 (NH4+). g The copper and silver enter the pyrolysis gas in their original form, mainly as copper sulfate, copper oxide, silver sulfate, and silver oxide phases, remaining in the solid form of the second roasting residue.

[0031] When the second pyrolysis gas is condensed at 50-130℃, Re2O7 (…) occurs. g )= Re2O7( s The condensable rhenium heptaoxide is converted from a gaseous state to a solid rhenium heptaoxide product. At this temperature, the non-condensable ammonia and a small amount of water vapor enter the ammonia recovery system, and are absorbed by dilute ammonia water to obtain industrial concentration ammonia water, which is then reused in the leaching and ammonia preparation process, thus realizing the separation of ammonia and rhenium.

[0032] 6. Because the heating of some materials involves the complete decomposition and gasification of all components, from a stoichiometric perspective, it is a reaction that increases the molar number of substances. This means that the decomposition reaction gas expands significantly and has a high gas velocity. To reduce the entrainment of undecomposed materials into the later stages by high-velocity gas, thin-layer heating is used for the decomposition reaction to ensure that the material has a large headspace cross-section and reduce mechanical entrainment of decomposition gas. The material thickness is controlled between 10-50 mm.

[0033] 7. Thus far, lead, antimony, bismuth, and gold are mainly enriched in the ammonia leaching residue, arsenic is mainly sublimated in the first thermal decomposition gas, rhenium is mainly sublimated in the second thermal decomposition gas, and copper and silver are mainly enriched in the second roasting residue. This has achieved the classification, enrichment, and partial productization of lead, antimony, bismuth, gold, rhenium, arsenic, copper, and silver.

[0034] Compared with the prior art, the advantages and beneficial effects of the method of the present invention are as follows: The innovation and core of this invention lies in using ammonia leaching instead of the original neutral or acidic leaching, maximizing the entry of valuable elements such as copper, arsenic, rhenium, and silver into the liquid phase. Then, a crystallization process is used to convert these valuable elements into solid salts. Finally, a segmented roasting-crystallization process separates arsenic, copper, silver, and rhenium, followed by further refining to form the relevant products. The significant advantage of this invention is its suitability for handling copper smelting dust with complex and unstable compositions, wide ranges in the content of individual elements, and low rhenium content limits, while also achieving a high degree of separation of valuable elements such as copper, arsenic, rhenium, silver, and lead. Attached Figure Description

[0035] Figure 1 This is a process flow diagram of the method of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0037] In the following examples, all raw materials used are common commercially available products that can be purchased directly, or can be prepared using conventional techniques in the art. Example

[0038] Examples of applications are as follows.

[0039] A 120.5 kg sample of rhenium-containing flue dust was taken. The flue dust composition was as follows: rhenium 93 g / t, copper 10.63%, arsenic 11.32%, lead 27.32%, silver 360.52 g / t, and sulfur (sulfide) 4.2%. The flue dust was processed according to the process plan (see flowchart for details). Figure 1 ).

[0040] 1. After adding hydrogen peroxide as an oxidant to the rhenium-containing flue dust, water is used to prepare the slurry. The liquid-to-solid ratio of the slurry is 3.5L:1kg. The amount of H2O2 (converted to 100% by mass) is 3.0 times the mass of sulfur element in the sulfides of the rhenium-containing flue dust. The slurry preparation temperature is 55℃ to obtain the prepared slurry.

[0041] 2. The slurry was leached with ammonia water at a concentration of 25%. The total mass of ammonia was controlled to be 0.6 times the total mass of copper, arsenic, and rhenium. The leaching temperature was 50℃, and the leaching time was 2 hours. After leaching, the residue was filtered and dried, yielding a dry weight of 78.7 kg of leaching residue with a leaching residue rate of 65.3%. The leaching residue contained 6 g / t of rhenium, 1.16% of copper, 1.89% of arsenic, 39.39% of lead, and 73.72 g / t of silver. The leaching rates of rhenium, copper, arsenic, and silver were 95.79%, 92.87%, 89.09%, and 86.65%, respectively. The lead recovery rate was 94.16%.

[0042] 3. The leachate was subjected to freeze crystallization at a temperature of -5℃ for 3 hours, yielding a total of 106.51 kg of wet freeze crystals. The crystallization liquid and the washing liquid were reused in the leaching process.

[0043] 4. Deep dehydration of the frozen crystals by low-temperature drying at 65℃. The water content of the dried material is 1.5%, and the weight of the dried material is 81.1 kg. The dry material contains 132 g / t rhenium, 14.67% copper, 14.99% arsenic, and 464.13 g / t silver.

[0044] 5. The dried crystals were subjected to a first closed-loop thin-layer thermal decomposition roasting. The first thermal decomposition temperature was controlled at 240℃, the thermal decomposition time was 1 hour, and the material thickness was 20 mm. The first thermal decomposition gas was induced to cool at 120℃ for 1 hour, yielding 16.11 kg of arsenic trioxide product with an arsenic trioxide content of 98.7% and an arsenic recovery rate of 87.43%. The non-condensable gas was absorbed by circulating dilute ammonia water to obtain industrial-concentration ammonia water. 36.23 kg of the first thermal decomposition residue was obtained, containing 295.23 g / t rhenium, 32.83% copper, 0.23% arsenic, and 1038.62 g / t silver.

[0045] 6. The residue from the first thermal decomposition was subjected to a second closed-loop thin-layer thermal decomposition roasting. The second thermal decomposition temperature was controlled at 350℃, the thermal decomposition time was 0.5h, and the material thickness was 20mm. The gas from the second thermal decomposition was induced to cool at 80℃ for 0.5h. The condensable components in the second thermal decomposition gas were cooled to rhenium oxide, yielding 121.23g of rhenium-enriched material containing 8.85% rhenium. The non-condensable gas was absorbed by circulating dilute ammonia water to obtain industrial-concentration ammonia water. 25.12kg of the second thermal decomposition residue was obtained, containing 47.32% copper and 1497.44 g / t of silver.

[0046] 7. The rhenium oxide concentrate was purified by dissolution, extraction, back-extraction, and crystallization to obtain 16.13 g of ammonium rhenate product with a purity of 95.02% and a total rhenium recovery rate of 94.93%. The dissolution step used 2.5 mol / L sulfuric acid at a liquid-to-solid ratio of L:S = 4:1 ml / g, at a temperature of 65℃, for 0.5 h. The extraction step used a mixed solvent of N235-2-octanol-kerosene, where N235 is trioctyldecyl tertiary amine as the main extractant, and 2-octanol and kerosene as diluents. The volume ratio of N235-2-octanol-kerosene was 20:20:60, the extraction phase ratio O / A = 1:1.5 (volume ratio), the extraction temperature was 25℃, and the extraction and phase separation time was 30 min. The back-extraction step used 3.5 mol / L ammonia water as the back-extraction agent, with a back-extraction ratio of O / A = 1.5:1 (volume ratio), a back-extraction temperature of 25℃, and a back-extraction and phase separation time of 30 min. The back-extraction solution was concentrated at 85℃ under normal pressure to a rhenium Re = 140 g / L; the concentrate was cooled at -5℃ for 8 h to obtain wet ammonium rhenium crystals; the wet ammonium rhenium crystals were washed with 0.5 mol / L ammonia water and pure water until neutral, and then dried at 75℃ for 2 h to obtain the ammonium rhenium product.

[0047] 8. The residue from the second thermal decomposition (enriched with copper oxide, silver oxide, etc.) was dissolved by adding 10% sulfuric acid, and silver was precipitated by adding solid sodium chloride. The mixture was then filtered to obtain a copper sulfate solution and solid silver chloride. The copper sulfate solution was evaporated and crystallized to obtain 30.42 kg of anhydrous copper sulfate with a purity of 97.51% and a total copper recovery rate of 92.61%. The solid silver chloride was slurried with water, and the pH was adjusted to 1 with hydrochloric acid. The acidic silver chloride slurry was replaced with 80-mesh iron powder. After replacement, the mixture was filtered to obtain crude silver powder. The crude silver powder was then treated with 15% hydrochloric acid to remove iron, filtered, washed with water, and dried to obtain 38.91 g of elemental silver powder with a purity of 96.25% and a total silver recovery rate of 86.20%.

Claims

1. A method for enriching and recovering copper and rhenium from rhenium-containing copper smelting dust, characterized in that, The steps include the following: 1) After adding an oxidant to the rhenium-containing flue dust, water is used to prepare the slurry at a temperature of 25-80℃ to obtain the prepared slurry. 2) The slurry is leached with ammonia water at a leaching temperature of 25-60℃ for 0.5-6 hours. After leaching, solid and liquid are separated to obtain leaching residue and leachate. 3) The leachate is subjected to freeze crystallization to obtain freeze crystals; 4) The frozen crystals are dried, and the dried material contains 0.5-2% water. 5) The dried crystals are subjected to a first closed thin-layer thermal decomposition roasting to obtain the first thermal decomposition residue; the first thermal decomposition temperature is controlled at 200-280℃, the decomposition time is 0.5-2h, and the material thickness is 10-50mm; the first thermal decomposition gas is subjected to induced cooling at a cooling temperature of 90-150℃ for 0.5-2h; the condensable components in the first thermal decomposition gas are cooled into arsenic trioxide particles; 6) The residue from the first thermal decomposition is subjected to a second closed thin-layer thermal decomposition roasting. The temperature of the second thermal decomposition is controlled at 300-380℃, the decomposition time is 0.5-1h, and the material thickness is 10-50mm. The gas from the second thermal decomposition is subjected to induced cooling at a temperature of 50-130℃ for 0.5-1h. The condensable components in the second thermal decomposition gas are cooled to rhenium oxide. 7) Rhenium oxide is dissolved, extracted, back-extracted and crystallized to obtain ammonium rheniumate product.

2. The method as described in claim 1, characterized in that, In step 1), the oxidant is selected from oxygen, ozone, oxygen-enriched air, or hydrogen peroxide; when hydrogen peroxide is used, the mass of H2O2 should be 2.3-5.0 times the mass of sulfur element in sulfides in rhenium-containing dust; when oxygen, ozone, or oxygen-enriched air is used, the mass of O2 should be 2.0-5.0 times the mass of sulfur element in sulfides in rhenium-containing dust.

3. The method as described in claim 1, characterized in that, In step 1), the liquid-to-solid ratio during slurry preparation is 2.5-5 L: 1 kg.

4. The method as described in claim 1, characterized in that, In step 2), the ammonia concentration is 10-28%, and the total mass of ammonia is controlled at 0.4-0.65 times the total mass of copper, arsenic and rhenium.

5. The method as described in claim 1, characterized in that, In step 3), the freezing temperature is -10~10℃ and the freezing time is 1-6h.

6. The method as described in claim 1, characterized in that, In step 4), the drying temperature is 40-90℃.

7. The method as described in claim 1, characterized in that, In step 7), the dissolution process is as follows: use 2-4 mol / L sulfuric acid, with a liquid-to-solid ratio of 3-8 ml:1 g, a dissolution temperature of 60-85℃, and a time of 0.5-2 h.

8. The method as described in claim 1, characterized in that, In step 7), the extraction is specifically performed as follows: the organic phase is extracted using a mixed solvent of N235-2-octanol-kerosene, with a volume ratio of N235-2-octanol-kerosene of 20:20:60, an extraction temperature of 20-30℃, and an extraction and phase separation time of 10-60 min.

9. The method as described in claim 1, characterized in that, In step 7), the back-extraction-crystallization process is as follows: 3.5-6 mol / L ammonia water is used as the back-extraction agent, the back-extraction temperature is 20-40℃, and the back-extraction and phase separation time is 10-60 min; the back-extraction solution is concentrated at 80-95℃ under normal pressure to 100-200 g / L of rhenium, and the concentrated solution is cooled at -10~0℃ for 8-24 h to obtain wet ammonium rhenium crystals; the wet ammonium rhenium crystals are washed with 0.5-1 mol / L ammonia water and pure water until neutral, and dried at 60-80℃ for 0.5-3 h to obtain the ammonium rhenium product.

10. The method as described in claim 1, characterized in that, The rhenium-containing flue dust contains: 5-5000 g / t of rhenium, 0.2-15% of copper, 2-60% of arsenic, 2-35% of lead, 1-10% of sulfur, and 5-500 g / t of silver.

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