Method for recovering fluorine, molybdenum and rhenium from high-fluorine low-molybdenum low-rhenium waste acid solution

Abstract

The invention provides a method for recovering fluorine, molybdenum and rhenium from a high-fluorine, low-molybdenum and low-rhenium waste acid solution. The method comprises the following steps: firstly, adding excessive anhydrous sodium sulfate particles into a waste acid solution, and carrying out fractional precipitation to obtain a high-purity sodium fluoride solid; the liquid after fluorine precipitation is circulated to serve as flue gas leacheate, and concentration enrichment of molybdenum and rhenium is achieved; and when the molybdenum concentration is greater than or equal to 2g / L, selectively extracting rhenium and molybdenum by adopting an extracting agent in sequence, washing the loaded organic phase through an aluminum sulfate solution to deeply remove fluorine, and finally, carrying out reverse extraction to obtain rhenium-rich and molybdenum-rich solutions. According to the method, a fluorine preferential precipitation-metal cascade extraction process is adopted, the technical problem that recycling is difficult in a high-fluorine environment is solved, and the method has the advantages of being simple in technological process, recyclable in reagent, high in equipment compatibility and the like and is suitable for high-fluorine waste acid resourceful treatment in the smelting industry of copper, lead, zinc, molybdenum and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resource recycling, and particularly relates to a method for recycling fluorine, molybdenum and rhenium from high-fluorine, low-molybdenum and low-rhenium waste acid solution. BACKGROUND

[0002] Molybdenum ore resources are often associated with fluorite ore in nature and contain trace amounts of rhenium elements. In the flotation process of molybdenum concentrate, fluorite ore is usually not completely removed for economic benefits, resulting in high concentrations of fluorine (F), low concentrations of molybdenum (Mo) and rhenium (Re) in the flue dust gas leaching solution produced in the fire smelting process of molybdenum concentrate. In this high-fluorine waste acid solution, the concentration of fluorine is usually as high as 10-60 g / L, while the concentration of molybdenum is only 0.5-2 g / L, and the concentration of rhenium is only 0.01-0.2 g / L. Due to the extremely high concentration ratio of fluorine to molybdenum and rhenium (F / Mo and F / Re), the traditional separation and recovery methods face great challenges. This high-fluorine environment not only increases the difficulty of subsequent treatment, but also significantly reduces the recovery efficiency of molybdenum and rhenium, and an efficient and economical technical solution is urgently needed to solve this problem.

[0003] Currently, common methods for recovering molybdenum and rhenium from acidic solutions include solvent extraction and ion exchange. However, these methods have obvious defects when applied to high-fluorine waste acid solutions. On the one hand, fluorine ions will be extracted or adsorbed synchronously with molybdenum and rhenium, causing a large amount of fluorine to be enriched in the organic phase or resin, interfering with the separation and purification of target metals. On the other hand, high fluorine concentration also exacerbates equipment corrosion and increases process costs. Although existing technologies attempt to suppress the interference of fluorine by adjusting the pH value or adding masking agents, these methods often have limited effect and may introduce new impurities or increase operational complexity. Therefore, how to efficiently recover molybdenum and rhenium while achieving selective separation of fluorine has become a technical problem that needs to be solved in the field.

[0004] In addition, the existing high-fluorine waste acid solution treatment process also has the problem of low resource utilization rate. Due to the low concentration of molybdenum and rhenium, direct recovery has poor economic efficiency; and the high concentration of fluorine limits the applicability of traditional methods. Although some studies have proposed step-by-step precipitation or adsorption schemes, these methods usually have a long process flow, high reagent consumption, and are difficult to achieve efficient separation of fluorine from molybdenum and rhenium. For example, although some processes can partially remove fluorine, the loss rate of molybdenum and rhenium is high, which cannot meet the needs of industrial production. Therefore, it is of great industrial application value to develop a technical solution that can simultaneously achieve efficient separation and recovery of fluorine, molybdenum and rhenium, while having the characteristics of simple process and low cost.

[0005] In summary, the prior art is faced with the problems of serious fluorine interference, low recovery efficiency of molybdenum and rhenium, and complex process flow when treating high-fluorine contaminated acid solution. It is necessary to develop new technical means to solve the separation problem of molybdenum and rhenium under high-fluorine environment, realize efficient removal and resource utilization of fluorine, and improve the recovery rate of molybdenum and rhenium, thereby providing technical support for the sustainable development of the metallurgical industry. SUMMARY

[0006] The reason why it is difficult to recover fluorine, molybdenum and rhenium from high-fluorine low-molybdenum low-rhenium contaminated acid solution is that the fluorine concentration in the contaminated acid solution is extremely high (≥10 g / L), while the concentrations of molybdenum (≤2 g / L) and rhenium (≤0.2 g / L) are extremely low, resulting in extremely large concentration ratio of fluorine to molybdenum and rhenium (F / Mo and F / Re). The high-fluorine environment not only interferes with the extraction or adsorption process of molybdenum and rhenium, causing fluorine and target metals to be enriched synchronously, but also exacerbates equipment corrosion and increases the difficulty of separation and purification; at the same time, the traditional method is difficult to efficiently remove fluorine while avoiding the loss of molybdenum and rhenium, and the direct recovery of low-concentration metals is economically poor, and the process is complex and costly. The present application aims to at least solve the above technical problems existing in the prior art. To this end, the present application provides a method for recovering fluorine, molybdenum and rhenium from high-fluorine low-molybdenum low-rhenium contaminated acid solution, which enriches the concentrations of molybdenum and rhenium, reduces the concentration ratio of F / Mo and F / Re, and improves the recovery efficiency of fluorine, molybdenum and rhenium by recycling the leaching solution.

[0007] The first aspect of the present application provides a method for recovering fluorine, molybdenum and rhenium from high-fluorine low-molybdenum low-rhenium contaminated acid solution, comprising the following steps:

[0008] S1: adding first anhydrous sodium sulfate particles to the high-fluorine low-molybdenum low-rhenium contaminated acid solution, stirring and reacting, and then standing to obtain a first upper suspension and a first sodium sulfate bottom residue, and discharging the first sodium sulfate bottom residue;

[0009] S2: filtering the first upper suspension to obtain a first sodium fluoride solid and a first fluorine-sedimented solution;

[0010] S3: returning the first fluorine-sedimented solution to smelting as a flue gas leaching solution, when the difference between the fluorine concentration in the flue gas leaching solution and the fluorine concentration in the high-fluorine low-molybdenum low-rhenium contaminated acid solution is less than 20%, adding the first sodium sulfate bottom residue, dissolving the first sodium sulfate bottom residue, adding second anhydrous sodium sulfate particles, stirring and reacting, and then standing to obtain a second upper suspension and a second sodium sulfate bottom residue, filtering the second upper suspension to obtain a second sodium fluoride solid and a second fluorine-sedimented solution, and returning the second fluorine-sedimented solution to smelting as a flue gas leaching solution to form a cycle;

[0011] S4: When the Mo concentration in the second fluorine precipitation solution is ≥2g / L, rhenium is extracted with rhenium extractant to separate the rhenium-loaded organic phase and the rhenium extraction residue. The rhenium-loaded organic phase is washed to separate the wash water and the washed rhenium-loaded organic phase. The washed rhenium-loaded organic phase is then back-extracted with rhenium to obtain a rhenium-rich solution.

[0012] S5: Extract molybdenum from the rhenium extraction residue using a molybdenum extractant to separate the molybdenum-loaded organic phase and the molybdenum extraction residue. After washing, the molybdenum-loaded organic phase is separated into wash water and washed molybdenum-loaded organic phase. The washed molybdenum-loaded organic phase is then subjected to molybdenum back-extraction to obtain a molybdenum-rich solution.

[0013] The method of the present invention for recovering fluorine, molybdenum, and rhenium from high-fluorine, low-molybdenum, and low-rhenium contaminated acid solutions has at least the following beneficial effects:

[0014] The method of this invention recycles the eluent, enriching the concentrations of molybdenum and rhenium, reducing the F / Mo and F / Re concentration ratios, and improving the recovery efficiency of molybdenum and rhenium. One of the innovations of this invention lies in achieving efficient separation of fluorine and selective enrichment of molybdenum and rhenium through a stepwise precipitation-circulating elution-co-extraction technical route. Specifically:

[0015] This significantly improved the removal efficiency and resource recovery rate of fluoride. Through stepwise precipitation with sodium sulfate, the single-pass fluoride recovery rate was ≥50% (reaching 51.7%–55.5% in the examples), and the recycling process further enhanced the overall recovery rate. The F content in the generated sodium fluoride solid was close to the theoretical value, and the impurities (SO4) were minimal. 2- The content of SO42- (Mo, Re) is extremely low. 2- Sodium sulfate (<0.5%, Mo<0.07%) can be directly reused as an industrial raw material (such as a flux in aluminum electrolysis). Sodium sulfate bottom slag can be reused (e.g., adding fresh sodium sulfate after dissolving the first bottom slag), reducing reagent consumption and lowering processing costs.

[0016] The recovery conditions for molybdenum and rhenium were optimized, improving enrichment efficiency. The F / Mo and F / Re ratios were reduced; initially, the F / Mo ratio in the sludge solution was 39 and F / Re was 1110. After cyclic fluoride precipitation, the F / Mo ratio in the second fluoride-precipitated solution was 11 and F / Re was 286, significantly reducing extraction interference from molybdenum and rhenium. High-efficiency enrichment of rhenium was achieved. Tertiary amine extractants (such as N235) were used for selective extraction of rhenium. After back-extraction, the Re / F ratio in the rhenium-rich solution increased from 0.003 to 1.040, with a rhenium recovery rate of up to 100% (example data). High-purity recovery of molybdenum was achieved. During the molybdenum extraction stage, aluminum sulfate was used to wash the loaded organic phase, achieving a fluoride washing efficiency of 70.3% (compared to only 44.4% with water washing). The final Mo / F ratio in the molybdenum-rich solution increased from 0.089 to 0.577, with a molybdenum recovery rate of 97.5%.

[0017] It offers both process synergy and environmental benefits. Firstly, the leaching solution is recycled; after fluoride precipitation, the solution is returned to the flue gas scrubbing system, enriching molybdenum and rhenium concentrations (Mo increases from 1.21 g / L to 2.22 g / L) while preventing wastewater discharge and achieving a closed-loop cycle. Secondly, secondary pollution is reduced; fluoride is fixed in the form of sodium fluoride, avoiding the generation of fluoride-containing sludge in traditional neutralization methods; the fluoride concentration in the raffinate is reduced to 11.2 g / L (example), significantly reducing the pressure on subsequent treatment. Thirdly, the equipment is highly compatible; the process requires no complex equipment and can be directly integrated with existing smelter hydrometallurgical systems.

[0018] The method of this invention offers significant economic benefits. It utilizes low-cost reagents, primarily sodium sulfate (an inexpensive industrial product), and the extractants (N235, 2-octanol) are reusable. The efficient recovery of rhenium (a strategic metal, expensive) and molybdenum (an essential industrial resource) further enhances the overall economic efficiency. Compared to traditional stepwise processing methods, energy consumption is reduced by more than 30% (estimated).

[0019] This invention solves the problem of difficult recovery of low-concentration molybdenum and rhenium from high-fluoride waste acid solutions through the technical path of "fluorine preferential separation - metal gradient enrichment - full resource recycling". It has three major advantages: high recovery rate, low cost and green process, and is applicable to pollution control and comprehensive resource utilization in the smelting industries of molybdenum, copper, lead and zinc.

[0020] According to some embodiments of the present invention, in step S1, the amount of the first anhydrous sodium sulfate particles added is 350 g / L to 500 g / L.

[0021] Controlling the addition of the first anhydrous sodium sulfate granules to 350 g / L to 500 g / L can avoid affecting the fluorine recovery rate due to insufficient sodium sulfate addition, and can also avoid sodium fluoride adsorbing onto sodium sulfate crystals and precipitating out due to excessive sodium sulfate bottom residue, making it impossible to separate sodium fluoride and sodium sulfate by standing, thus affecting the separation effect of sodium fluoride and sodium sulfate.

[0022] According to some embodiments of the present invention, the amount of the first anhydrous sodium sulfate particles added is any value among 350 g / L, 400 g / L, 420 g / L, 440 g / L, 460 g / L, 480 g / L, and 500 g / L, such as 400 g / L, or any range formed by both, such as 400 g / L to 440 g / L.

[0023] When the difference between the fluoride concentration in the flue gas scrubbing liquid and the fluoride concentration in the high-fluoride, low-molybdenum, low-rhenium sludge solution is less than 20%, the "fluoride concentration" here refers to the fluoride content in the flue gas scrubbing liquid and the high-fluoride, low-molybdenum, low-rhenium sludge solution, and the unit can be "g / L".

[0024] According to some embodiments of the present invention, in the first anhydrous sodium sulfate particles, more than 90% of the particles have a particle size greater than 425 micrometers. In step S2, in the sodium fluoride solid, more than 90% of the particles have a particle size less than 100 micrometers.

[0025] The sodium fluoride precipitate formed by the reaction has a particle size of less than 100 micrometers in over 90%. Adding an excess of large-particle anhydrous sodium sulfate solid results in a sodium sulfate bottom residue with a particle size of more than 200 micrometers in over 90% of its particles. Sodium fluoride has a specific gravity of 2.79, while anhydrous sodium sulfate has a specific gravity of 2.70. According to Stokes' equation, the settling velocity of sodium sulfate is approximately 3.5-3.8 times that of sodium fluoride. Therefore, the sodium sulfate bottom residue can be preferentially discharged for sodium sulfate recovery.

[0026] According to some embodiments of the present invention, in step S1, the temperature of the stirring reaction is 35°C to 45°C.

[0027] According to some embodiments of the present invention, the temperature of the stirring reaction is any value among 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, and 45°C, such as 40°C, or a range of any two, such as 40°C to 42°C.

[0028] According to some embodiments of the present invention, the stirring reaction time is 4h to 24h.

[0029] According to some embodiments of the present invention, the stirring reaction time is any value among 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, and 24h, such as 16h, or a range of any two, such as 12h to 18h.

[0030] According to some embodiments of the present invention, the settling time is 2 min to 5 min.

[0031] According to some embodiments of the present invention, the settling time is any value among 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, and 5 min, such as 3 min, or any range formed by both, such as 3 min to 4 min.

[0032] According to some embodiments of the present invention, in step S4, the rhenium extractant includes a tertiary amine extractant or a primary amine extractant.

[0033] According to some embodiments of the present invention, in step S4, the rhenium back-extraction agent is an alkaline solution.

[0034] According to some embodiments of the present invention, the alkaline solution includes sodium hydroxide solution, sodium carbonate solution, or ammonia solution.

[0035] According to some embodiments of the present invention, in step S4, the detergent supporting the rhenium organic phase can be water.

[0036] According to some embodiments of the present invention, in step S5, the molybdenum extractant includes a tertiary amine extractant or a primary amine extractant.

[0037] According to some embodiments of the present invention, in step S5, the stripping agent in the molybdenum back-extraction is an alkaline solution.

[0038] According to some embodiments of the present invention, the alkaline solution includes sodium hydroxide solution, sodium carbonate solution, or ammonia solution.

[0039] According to some embodiments of the present invention, in step S5, the detergent loaded with the molybdenum organic phase can be water, aluminum sulfate solution or aluminum chloride solution.

[0040] Washing the molybdenum-loaded organic phase with aluminum sulfate solution yielded higher washing efficiency with fluorine compared to conventional water washing. This is because Al... 3+ The electronic configuration is 3s 0 3p 0 The outermost shell contains empty orbitals, which can act as electron docking acceptors to accommodate lone pairs of ligands; the F- outermost shell has 4 lone pairs of electrons, and F... - Small radius, concentrated charge, and Al 3+ It has good size matching (the ratio of ionic radii is suitable for forming tight coordination) and can form stable complex ligands.

[0041] According to some embodiments of the present invention, in the first anhydrous sodium sulfate particles and the second anhydrous sodium sulfate particles, more than 90% of the particles have a particle size greater than 425 micrometers.

[0042] The sodium fluoride precipitate formed by the reaction has a particle size of less than 100 micrometers in over 90%. Adding an excess of large-particle anhydrous sodium sulfate solid results in a sodium sulfate bottom residue with a particle size of more than 200 micrometers in over 90% of its particles. Sodium fluoride has a specific gravity of 2.79, while anhydrous sodium sulfate has a specific gravity of 2.70. According to Stokes' equation, the settling velocity of sodium sulfate is approximately 3.5-3.8 times that of sodium fluoride. Therefore, the sodium sulfate bottom residue can be preferentially discharged for sodium sulfate recovery.

[0043] According to some embodiments of the present invention, in the sodium fluoride solid, more than 90% of the particles have a particle size of less than 100 micrometers.

[0044] According to some embodiments of the present invention, the method achieves a single-pass fluorine recovery rate of ≥50%.

[0045] According to some embodiments of the present invention, the high-fluorine, low-molybdenum, and low-rhenium contaminated acid solution has a fluorine content ≥10g / L, a molybdenum content ≤2g / L, and a rhenium content ≤0.2g / L.

[0046] According to some embodiments of the present invention, the fluoride content in the high-fluoride acid solution is 10-60 g / L.

[0047] The second aspect of the present invention provides the application of the method of the first aspect of the present invention in the pyrometallurgical smelting of copper, lead, zinc and molybdenum. Detailed Implementation

[0048] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0049] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0051] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0052] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0053] Example

[0054] Fluorine, molybdenum, and rhenium were separated from a high-fluoride acidic solution obtained from molybdenum pyrometallurgical processes. Ion chromatography analysis revealed that the fluorine content in this acidic solution was 46.6 g / L, the molybdenum content was 1.21 g / L, and the rhenium content was 0.042 g / L.

[0055] The specific steps are as follows:

[0056] S1: Add the first anhydrous sodium sulfate particles to the high-fluorine, low-molybdenum, and low-rhenium sludge solution, stir and react, and then let stand to obtain the first upper suspension and the first sodium sulfate bottom residue. Discharge the first sodium sulfate bottom residue.

[0057] S2: Filter the first upper suspension to obtain the first sodium fluoride solid and the first fluoride-precipitated liquid;

[0058] S3: The first fluoride-precipitated liquid is returned to the smelting process as flue gas scrubbing liquid. When the difference between the fluoride concentration in the flue gas scrubbing liquid and the fluoride concentration in the high-fluoride, low-molybdenum, and low-rhenium contaminated acid solution is less than 20%, the first sodium sulfate bottom slag is added. After the first sodium sulfate bottom slag dissolves, the second anhydrous sodium sulfate particles are added. After stirring and reacting, the mixture is allowed to stand to obtain the second upper suspension and the second sodium sulfate bottom slag. The second upper suspension is filtered to obtain the second sodium fluoride solid and the second fluoride-precipitated liquid. The second fluoride-precipitated liquid is returned to the smelting process as flue gas scrubbing liquid to form a cycle.

[0059] S4: When the Mo concentration in the second fluorine precipitation solution is ≥2g / L, rhenium is extracted with rhenium extractant to separate the rhenium-loaded organic phase and the rhenium extraction residue. After washing, the rhenium-loaded organic phase is separated into wash water and washed rhenium-loaded organic phase. The washed rhenium-loaded organic phase is then back-extracted with rhenium to obtain a rhenium-rich solution.

[0060] S5: Extract molybdenum from the rhenium extraction residue using a molybdenum extractant to separate the molybdenum-loaded organic phase and the molybdenum extraction residue. After washing, separate the washing water and the washed molybdenum-loaded organic phase. Perform molybdenum back-extraction on the washed molybdenum-loaded organic phase to obtain a molybdenum-rich solution.

[0061] In step S1:

[0062] The first addition amount of anhydrous sodium sulfate granules is 450 g / L.

[0063] In the first anhydrous sodium sulfate granules, more than 90% of the particles have a diameter greater than 425 micrometers.

[0064] The temperature for the stirring reaction is around 40℃.

[0065] The stirring reaction was carried out for 24 hours.

[0066] The settling time is 3 minutes.

[0067] In step S2:

[0068] In the first sodium fluoride solid, more than 90% of the particles have a diameter of less than 100 micrometers.

[0069] In step S4:

[0070] The rhenium extractant is specifically 5% N235 + 5% 2-octanol + 90% kerosene, with an O / A ratio of 1 / 1.5 for rhenium extraction.

[0071] The rhenium-loaded organic phase was washed with pure water at a ratio of O / A = 10 / 1 to remove impurities entrained in the organic phase. The wash water and the washed rhenium-loaded organic phase were then separated. The washed rhenium-loaded organic phase was back-extracted with 5% sodium hydroxide solution at a ratio of O / A = 10 / 1 to obtain a rhenium-rich solution.

[0072] In step S5:

[0073] The molybdenum extractant was specifically 15% N235 + 15% 2-octanol + 70% kerosene. Molybdenum was extracted using an O / A ratio of 2 / 1, separating the residual extract and the molybdenum-loaded organic phase. The molybdenum-loaded organic phase was washed with 30 g / L aluminum sulfate solution at an O / A ratio of 2 / 1 to remove fluorine, separating the wash water and the washed molybdenum-loaded organic phase. The washed molybdenum-loaded organic phase was then subjected to molybdenum back-extraction.

[0074] In the molybdenum back-extraction process, the back-extraction agent is specifically a 10% sodium hydroxide solution. Molybdenum is back-extracted at a ratio of O / A = 10 / 1 to obtain a molybdenum-rich solution.

[0075] Fluorine recovery rate in a single run ≥ 50%.

[0076] The test results are shown in Tables 2 and 3. These include the fluorine content, rhenium content, molybdenum content, and SO4 content. 2- The content was determined by ion chromatography.

[0077] Table 2

[0078]

[0079] Note: Precipitation rate = [1 - element concentration of the first fluoride precipitation liquid × volume of the first fluoride precipitation liquid / (element concentration of the first waste acid solution × volume of the first waste acid solution)] × 100%.

[0080] Table 3

[0081] Name Weight kg F content SO4 2- content Mo content Re content First sodium fluoride solid 48.4 44.60％ 0.45％ 0.03％ 0.0005％ First sodium sulfate bottom residue 27.8 9.04％ 53.40％ 0.07％ 0.0008％

[0082] The theoretical value of the F content in sodium fluoride is 19 / 42 × 100% = 45.24%.

[0083] In Table 3, the solid weight of sodium fluoride 1 is 48.4 kg, and the F content is 44.60% (close to the theoretical value of 45.24%), indicating high purity. SO4 2- The content is only 0.45%, the Mo content is only 0.03%, and the Re content is only 0.0005%, indicating that the fluorine separation effect is good.

[0084] After the first fluoride precipitation, the liquid is returned to continue as flue gas scrubbing liquid. When the fluoride content reaches 53.6 g / L, 27.8 kg of the first sodium sulfate bottom residue is added, and 208.6 kg of the second anhydrous sodium sulfate granules are added.

[0085] Table 4

[0086]

[0087] In Table 4, the fluoride concentration in the flue gas scrubbing liquid rebounded to 53.6 g / L (close to the initial value), and the F precipitation rate was 55.5%. This indicates that the circulating process has good stability, the fluoride recovery rate remains at a high level, and the repeatability of the method is verified.

[0088] Table 5

[0089] Name Weight kg F content SO4 2- content]]> Mo content Re content Second sodium fluoride solid 69.4 44.30％ 0.47％ 0.07％ 0.0005％ Second sodium sulfate bottom residue 41.6 10.44％ 51.80％ 0.09％ 0.0009％

[0090] In Table 5, the solid F content of sodium fluoride II is 44.30%, and SO4 content is... 2- The content is 0.47%, which is similar to that of the first round, indicating that the product purity is stable.

[0091] Sodium fluoride and sodium fluoride solids contain trace amounts of molybdenum and rhenium, which can be recrystallized later. The molybdenum and rhenium are dissolved in the recrystallization mother liquor, which is used as flue gas leaching liquid to prevent the loss of molybdenum and rhenium outside the system.

[0092] The first sludge solution had F / Mo = 39 and F / Re = 1110. After fluoride precipitation, the second fluoride-precipitated solution had F / Mo = 11 and F / Re = 286, with the ratios significantly reduced.

[0093] In Table 4, the second fluoride precipitation solution was used to extract rhenium using 5% N235 + 5% 2-octanol + 90% kerosene at a ratio O / A = 1 / 1.5. The rhenium extraction residue and the rhenium-loaded organic phase were separated. The rhenium-loaded organic phase was washed with pure water at a ratio O / A = 10 / 1 to remove impurities entrained in the organic phase. The wash water and the washed rhenium-loaded organic phase were separated. The washed rhenium-loaded organic phase was back-extracted with 5% sodium hydroxide solution at a ratio O / A = 10 / 1 to obtain a rhenium-rich solution.

[0094] Table 6

[0095] Name F (g / L) Mo (g / L) Re (g / L) Mo / F Re / F Second fluorination residue 22.9 2.06 0.08 0.090 0.003 Rhenium extraction raffinate 22.5 2.01 0 0.089 0.000 Wash water 4.86 0.039 0.0144 0.008 0.003 Rhenium-rich solution 1.14 0.711 1.1856 0.624 1.040

[0096] The Re / F ratio in the second fluoride precipitation solution was 0.003. After extraction-back-extraction enrichment, the Re / F ratio in the resulting rhenium-rich solution increased to 1.040.

[0097] The residual extract of rhenium was used to extract molybdenum using 15% N235 + 15% 2-octanol + 70% kerosene at a ratio of O / A = 2 / 1. The residual extract and the molybdenum-loaded organic phase were separated. The molybdenum-loaded organic phase was washed with 30 g / L aluminum sulfate solution at a ratio of O / A = 2 / 1 to remove fluorine. The wash water and the washed molybdenum-loaded organic phase were separated. The washed molybdenum-loaded organic phase was back-extracted with 10% sodium hydroxide solution at a ratio of O / A = 10 / 1 to obtain a molybdenum-rich solution.

[0098] In Table 6, the initial concentration of rhenium in the second fluorine precipitation solution was extremely low (0.08 g / L), but after extraction-back-extraction, the concentration of rhenium in the rhenium-rich solution increased significantly to 1.1856 g / L, and the Re / F ratio increased from 0.003 to 1.040, indicating that rhenium was highly enriched and the extraction process was extremely selective for rhenium (extraction rate 100%), achieving highly efficient and selective extraction of rhenium.

[0099] The concentrations of fluorine (22.5 g / L) and molybdenum (2.01 g / L) in the rhenium extraction residue showed little change (Mo / F≈0.089), indicating that the co-extraction rate of fluorine and molybdenum during the rhenium extraction stage was extremely low (F extraction rate was only 1.7%, and Mo extraction rate was 2.4%), thus controlling the interference of fluorine and molybdenum.

[0100] The rhenium content in the wash water (0.0144 g / L) was extremely low, indicating that the removal of impurities (such as fluorine and molybdenum) from the rhenium-loaded organic phase after washing was effective, further ensuring the purity of the rhenium-rich solution.

[0101] To avoid the loss of molybdenum and rhenium in the wash water, the wash water can be returned to the second fluoride precipitation liquid circulation.

[0102] Table 6 shows that the method of the present invention can efficiently and selectively extract rhenium in a high-fluorine environment. By optimizing the process, it can achieve near-complete recovery of rhenium (100% extraction rate) and high-purity enrichment (Re / F increased by 346 times), providing a reliable solution for the recovery of low-concentration rhenium.

[0103] Table 7

[0104] Name F Mo Re Extraction rate 1.7％ 2.4％ 100.0％ Wash rate 81.00％ 5.20％ 1.20％ Strip rate 100％ 100％ 100％

[0105] As shown in Table 7, the extraction rate of rhenium (Re) reached 100%, indicating that the method of the present invention, combined with the extractant (5% N235 + 5% 2-octanol + 90% kerosene), has extremely strong selectivity for rhenium and completely extracted rhenium from the liquid after the second fluorine precipitation.

[0106] The extraction rate of fluorine (F) was only 1.7%, and the extraction rate of molybdenum (Mo) was 2.4%, indicating that the selectivity of this extraction system for rhenium is much higher than that for fluorine and molybdenum, effectively reducing the interference of impurity metals.

[0107] The fluoride washing rate is as high as 81%, indicating that the water washing step can effectively remove fluoride entrained in the organic phase and prevent it from affecting the subsequent back-extraction process.

[0108] The low washing rates of molybdenum and rhenium (Mo 5.2%, Re 1.2%) indicate minimal loss of the target metal (rhenium) during the washing process, further improving the purity of the rhenium-rich solution. The washing process effectively removed impurities.

[0109] The back-extraction rates for fluorine, molybdenum, and rhenium were all 100%, indicating that the method of this invention, combined with the back-extraction agent (5% NaOH solution), can completely transfer rhenium from the loaded organic phase to the aqueous phase, forming a high-concentration rhenium-rich solution (Re / F = 1.040 in Table 6).

[0110] Therefore, the method of this invention exhibits extremely high selectivity for rhenium, achieving near-complete recovery of rhenium (100% extraction rate) even in high-fluoride, low-rhenium environments. The water washing step effectively removes fluoride (washing rate 81%), while the back-extraction step ensures efficient enrichment of rhenium (100% back-extraction rate). The process provided by this invention offers a reliable technical solution for the efficient separation and recovery of rhenium from complex high-fluoride acidic solutions, featuring both high recovery rate and low impurity interference.

[0111] Table 8

[0112] Name F (g / L) Mo (g / L) Mo / F Rhenium extraction raffinate 22.5 2.0 0.089 Molybdenum extraction raffinate 11.2 0.1 0.004 Wash water 7.9 0.0 0.003 Molybdenum-rich solution 16.8 9.7 0.577

[0113] The Mo / F ratio in the rhenium extraction residue was 0.089. After extraction-back-extraction enrichment, the Mo / F ratio in the resulting molybdenum-rich solution increased to 0.577.

[0114] As shown in Table 8, the initial molybdenum concentration in the rhenium extraction residue was 2.0 g / L (Mo / F = 0.089). After extraction, the molybdenum concentration in the molybdenum-rich solution increased to 9.7 g / L (Mo / F = 0.577), representing an enrichment factor of 6.5 times. The molybdenum concentration in the molybdenum extraction residue decreased to 0.1 g / L, indicating a molybdenum extraction rate as high as 97.5% (consistent with Table 9), achieving highly efficient molybdenum extraction.

[0115] The fluoride concentration decreased from 22.5 g / L in the rhenium extraction residue to 11.2 g / L in the molybdenum extraction residue, achieving an extraction rate of 50.2%. After washing with aluminum sulfate solution, the fluoride concentration in the wash water was 7.9 g / L, with a washing efficiency of 70.3% (Table 9). However, when the aluminum sulfate solution used as the detergent in step S5 to support the molybdenum organic phase was replaced with pure water, the fluoride washing rate was only 44.4%, which was 25.9% lower than that of aluminum sulfate washing, significantly better than water washing, achieving effective fluoride separation. The Mo / F ratio increased from the initial 0.089 to 0.577 in the molybdenum-rich solution, a 6.5-fold increase, significantly improving the molybdenum purity in the molybdenum-rich solution, creating favorable conditions for subsequent purification, and demonstrating good selective enrichment.

[0116] The process of this invention employs an extraction system of 15% N235 + 15% 2-octanol + 70% kerosene, combined with aluminum sulfate washing, to efficiently recover low-concentration molybdenum (recovery rate 97.5%). The innovative aluminum sulfate washing step significantly improves fluoride removal (washing rate 70.3%), solving the problem of molybdenum purification in high-fluoride environments. Furthermore, through a staged extraction strategy, rhenium is extracted first, followed by molybdenum, achieving efficient separation and enrichment of the two rare and precious metals. The final molybdenum-rich solution (Mo 9.7 g / L) can be directly used in subsequent refining processes, demonstrating significant industrial application value. The above data verify the feasibility of the fluoride-preferential separation-metal gradient enrichment technology route of this invention, providing an optimized solution for the resource-based treatment of high-fluoride, low-molybdenum waste acid solutions.

[0117] Table 9

[0118] Name F Mo Extraction rate 50.2％ 97.5％ Wash rate 70.3％ 1.2％ Strip rate 100％ 100％

[0119] As can be seen from Table 9:

[0120] The extraction rate of molybdenum (Mo) reached 97.5%, indicating that the process combined with the extraction system (15% N235 + 15% 2-octanol + 70% kerosene) of the present invention has a very strong ability to capture molybdenum. The 100% back-extraction rate proves that the back-extraction process (10% NaOH solution) can completely recover molybdenum in the organic phase, achieving ultra-high efficiency recovery of molybdenum.

[0121] When washing with a 30 g / L aluminum sulfate solution, the washing efficiency of fluoride (F) is as high as 70.3%, which is 25.9% higher than that of traditional water washing.

[0122] Furthermore, the molybdenum loss rate during the washing stage was only 1.2%, indicating that aluminum sulfate can effectively remove fluoride while retaining the target metal molybdenum. When used in conjunction with the rhenium extraction process (Table 7), it achieves the stepwise separation of fluorine, rhenium, and molybdenum.

[0123] The method of this invention achieves a total molybdenum recovery rate of >90%. To further improve the molybdenum recovery rate, the precipitated sodium fluoride can be recrystallized, and the mother liquor from the crystallization can be returned as a flue gas scrubbing liquid. Ultimately, the Mo / F ratio of the molybdenum-rich liquid is increased to 0.577 (see Table 8), which meets the requirements for subsequent refining. The aluminum sulfate washing step solves the industry problem of molybdenum purification in a high-fluoride environment.

[0124] This invention achieves, for the first time, highly efficient molybdenum recovery (97.5%) from high-fluoride, low-molybdenum wastewater; innovatively employs an aluminum sulfate washing process, increasing fluoride removal efficiency by 13.5 times; establishes a complete technical route for preferential fluoride separation and dedicated molybdenum enrichment; and provides an industrial solution for molybdenum resource recovery from high-fluoride wastewater in the smelting industry. These achievements not only solve the technical bottlenecks of severe fluoride interference and low molybdenum recovery rates in traditional processes, but also significantly reduce treatment costs through reagent recycling (such as the reuse of sodium sulfate bottom slag), demonstrating both environmental and economic value.

[0125] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for recovering fluorine, molybdenum, and rhenium from a high-fluorine, low-molybdenum, and low-rhenium contaminated acid solution, characterized in that, Includes the following steps: S1: Add the first anhydrous sodium sulfate particles to the high-fluorine, low-molybdenum, and low-rhenium sludge solution, stir and react, and then let stand to obtain the first upper suspension and the first sodium sulfate bottom residue. Discharge the first sodium sulfate bottom residue. S2: Filter the first upper suspension to obtain the first sodium fluoride solid and the first fluoride-precipitated liquid; S3: The first fluoride-precipitated liquid is returned to the smelting process as a flue gas scrubbing liquid. When the difference between the fluoride concentration in the flue gas scrubbing liquid and the fluoride concentration in the high-fluoride, low-molybdenum, and low-rhenium contaminated acid solution is less than 20%, the first sodium sulfate bottom residue is added. After the first sodium sulfate bottom residue dissolves, the second anhydrous sodium sulfate particles are added. After stirring and reacting, the mixture is allowed to stand to obtain the second upper suspension and the second sodium sulfate bottom residue. The second upper suspension is filtered to obtain the second sodium fluoride solid and the second fluoride-precipitated liquid. The second fluoride-precipitated liquid is returned to the smelting process as a flue gas scrubbing liquid to form a cycle. S4: When the Mo concentration in the second fluorine precipitation solution is ≥2g / L, rhenium is extracted with rhenium extractant to separate the rhenium-loaded organic phase and the rhenium extraction residue. The rhenium-loaded organic phase is washed to separate the wash water and the washed rhenium-loaded organic phase. The washed rhenium-loaded organic phase is then back-extracted with rhenium to obtain a rhenium-rich solution. S5: Extract molybdenum from the rhenium extraction residue using a molybdenum extractant to separate the molybdenum-loaded organic phase and the molybdenum extraction residue. After washing, the molybdenum-loaded organic phase is separated into wash water and washed molybdenum-loaded organic phase. The washed molybdenum-loaded organic phase is then subjected to molybdenum back-extraction to obtain a molybdenum-rich solution.

2. The method according to claim 1, characterized in that, In step S1, the amount of the first anhydrous sodium sulfate particles added is 350 g / L to 500 g / L.

3. The method according to claim 1, characterized in that, In step S1, the temperature of the stirring reaction is 35℃~45℃; and / or, the stirring reaction time is 4h~24h; and / or, the settling time is 2min~5min.

4. The method according to claim 1, characterized in that, In step S4, the rhenium extractant includes tertiary amine extractants or primary amine extractants.

5. The method according to claim 1, characterized in that, In step S4, the rhenium back-extraction agent is an alkaline solution; and / or, the alkaline solution includes sodium hydroxide solution, sodium carbonate solution, or ammonia solution.

6. The method according to claim 1, characterized in that, In step S5, the molybdenum extractant includes tertiary amine extractants or primary amine extractants.

7. The method according to claim 1, characterized in that, In step S5, the stripping agent in the molybdenum back-extraction is an alkaline solution; and / or, the alkaline solution includes sodium hydroxide solution, sodium carbonate solution, or ammonia solution.

8. The method according to any one of claims 1 to 7, characterized in that, The method described achieves a single-cycle fluorine recovery rate of ≥50%.

9. The method according to any one of claims 1 to 7, characterized in that, The high-fluorine, low-molybdenum, and low-rhenium contaminated acid solution has a fluorine content ≥10g / L, a molybdenum content ≤2g / L, and a rhenium content ≤0.2g / L.

10. The application of the method as described in any one of claims 1 to 9 in the pyrometallurgical smelting of copper, lead, zinc, and molybdenum.

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