Separation and extraction method for rhenium in smelting waste acid

Abstract

The invention discloses a method for separating and extracting rhenium in smelting waste acid, which comprises the following steps: adding hydrogen peroxide into rhenium-containing waste acid for oxidation, adding Na2S for copper precipitation and molybdenum precipitation, acidifying supernate, extracting by adopting an extraction organic phase formed by mixing TOA, sec-octyl alcohol and kerosene, and carrying out chemical reverse extraction on the extraction phase by using ammonia water, and carrying out condensation crystallization and vacuum filtration on the strip liquor to obtain ammonium rhenate solid powder and the like. According to the method, a separation and extraction method of precipitation-extraction-condensation crystallization is adopted, and high-selectivity extraction of the high-valence rhenium compound is carried out through TOA, so that effective extraction of rhenium can be completed only through primary extraction and reverse extraction, the process period of rhenium extraction is effectively shortened, the total yield of rhenium reaches 99% or above, and the method is suitable for industrial production. And the mass fraction of the produced ammonium rhenate product is greater than 99.9%, and the method has the advantages of low process technology cost and easier realization of industrialization.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-ferrous metal metallurgy, and particularly relates to a method for separating and extracting rhenium from waste acid containing rhenium in copper and molybdenum smelting. Background Art

[0002] Rhenium is a very scarce metal. In nature, it mainly exists in molybdenite and chalcopyrite in the form of rhenium disulfide (ReS2) or rhenium heptasulfide (Re2S7), and its mass fraction is generally between 10 - 300 mg / L. Therefore, recovering rhenium from the waste of copper and molybdenum smelting, such as smelting soot, slag, and waste acid, is currently the main way to obtain rhenium at home and abroad. Among them, the rhenium content in the waste acid of copper and molybdenum smelting is 3 - 50 mg / L, with a relatively high content, mainly existing in the form of a mixture of different valence state compounds such as HReO4, Re2O7, ReO2, and ReO3.

[0003] Currently, the extraction of rhenium from rhenium-containing materials mainly involves processes such as separation, enrichment, and concentration crystallization, and finally produces potassium perrhenate or ammonium perrhenate products. The methods involved include chemical precipitation method, ion exchange method, solvent extraction method, and extraction resin method, etc. Among them, the ion exchange method is suitable for rhenium-containing materials with a relatively low rhenium concentration, such as the leaching solution of smelting slag, and the solvent extraction method is suitable for rhenium-containing materials with a relatively high rhenium concentration, such as smelting waste acid.

[0004] Currently, the extraction of rhenium from waste acid containing rhenium mostly uses N235 (trioctyl tertiary amine) and TBP (tributyl phosphate) as extractants. The extraction rate of N235 or TBP is generally between 85% - 92%. Therefore, a multi-stage extraction process is required to meet the better extraction requirements. There are problems such as low single-stage extraction rate, long time-consuming for multi-stage extraction, large site occupation, and low overall extraction efficiency. Moreover, there are problems that the third phase generated during extraction is not conducive to subsequent separation operations, and the extractant is easily lost during the stripping process, increasing production costs. Summary of the Invention

[0005] The purpose of the present invention is to propose a method for separating and extracting rhenium from smelting waste acid to solve the above problems existing in the extraction of rhenium from waste acid containing rhenium by using the multi-stage extraction method.

[0006] The present invention is realized through the following technical solutions:

[0007] The present invention proposes a method for separating and extracting rhenium from smelting waste acid, comprising the following steps:

[0008] S1. Add hydrogen peroxide with a mass concentration of 30% to the rhenium-containing waste acid generated from copper and molybdenum smelting. The addition amount is 10% of the total amount of waste acid. Then add Na2S for copper and molybdenum precipitation. The addition amount of Na2S is 10 - 15 g / L. Adjust the temperature of the waste acid to 50 - 70 °C, and use a stirrer to stir at a speed of 110 - 130 r / min for 5 - 10 min for thorough mixing. After mixing, let it stand for 5 - 10 min to separate the mixed liquid into layers.

[0009] S2. Extract the supernatant and add sulfuric acid for acidification for 5 - 10 min to obtain an acidified solution. The addition amount of sulfuric acid is determined according to the sulfuric acid content of 5 - 7 wt% in the supernatant.

[0010] S3. Extraction: Perform organic extraction on the acidified solution prepared in step S2. Use tri-n-octylamine (TOA) as the extractant, sec-octanol as the cosolvent, and kerosene as the diluent. Mix them evenly to form an extraction organic phase. Among them, the volume ratio of the extractant, cosolvent, and diluent is 1:1:3, and the volume ratio of the organic phase to the aqueous phase is O / A = 1 / 2. Mix and stir the acidified solution and the extraction organic phase at room temperature for 10 - 20 min, then let it stand for separation. The aqueous phase is discarded after harmless treatment.

[0011] S4. Back-extraction: Take the extraction phase in step S3 and use ammonia water with a concentration of 7 mol / L as the back-extraction agent for back-extraction. Set the volume ratio of the extraction phase to the back-extraction agent as O / A = 2 / 1. Mix and stir at room temperature for 10 - 20 min, then let it stand for separation. Carry out phase separation at a phase flow rate of 0.5 - 1 L / min to obtain a back-extracted solution, which is ammonium perrhenate solution.

[0012] S5. Purification, condensation, and crystallization: Place the back-extracted solution in an environment of -10 to 0 °C for cooling crystallization. Vacuum filter the back-extracted residue after crystallization, and take the crystallized product to obtain ammonium perrhenate solid powder.

[0013] Based on the above separation and extraction method, by adding hydrogen peroxide to the rhenium-containing waste acid, all low-valent rhenium compounds in the waste acid are converted into high-valent rhenium compounds. And by the reaction of Na2S with copper ions to form copper sulfide, and the adsorption and precipitation of molybdenum ions by copper sulfide, the main impurities in the waste acid are removed, and a rhenium-containing solution with higher purity is obtained. Further, through the ion association reaction of the extractant TOA with high-valent rhenium compounds, efficient extraction is achieved. Then, through ammonia water back-extraction and condensation crystallization, high-purity ammonium perrhenate solid powder can be obtained. The entire separation and extraction process only requires one-stage extraction and back-extraction to effectively extract rhenium, greatly optimizing the rhenium extraction process.

[0014] Preferably, before step S5, there is also step S6 of concentration and enrichment: mix the stripping solutions obtained in batches according to step S4, collect them until a certain amount is reached, and then conduct unified concentration and enrichment. First, heat the stripping solution at 30 - 40 °C to remove unreacted ammonia water, and then heat it at 90 - 100 °C to remove excess water to obtain a rhenium-rich solution; then perform the purification, condensation, and crystallization of step S5 on the rhenium-rich solution. The purpose of this process setting is to reduce the vacuum filtration load of step S5, further compress the process cycle, and be more suitable for industrial production.

[0015] Preferably, add sulfuric acid to acidify the stripping raffinate obtained in step S4 for 5 minutes. The addition amount of sulfuric acid is determined according to the stripping raffinate containing 5 - 7 wt% sulfuric acid. The purpose of this process setting is to realize the regeneration and recycling of the extraction organic phase, thereby reducing the process cost.

[0016] The beneficial effects of the present invention are as follows: By adding hydrogen peroxide to the rhenium-containing waste acid, all low-valence rhenium compounds in the waste acid are converted into high-valence rhenium compounds, and by reacting Na2S with copper ions to form copper sulfide, and the adsorption and precipitation of copper sulfide on molybdenum ions to remove the main impurities in the waste acid, a rhenium-containing solution with relatively high purity is obtained; further, through the high selectivity and ion association reaction of the extractant TOA with high-valence rhenium compounds, the rhenium extraction rate reaches 99% or more for efficient extraction, and then high-purity ammonium perrhenate solid powder can be obtained through chemical stripping with ammonia water and condensation crystallization. The entire separation and extraction process only needs to go through one-stage extraction and stripping to effectively extract rhenium, greatly optimizing the rhenium extraction process, reducing the process technology cost, and being more easily industrialized. Through the separation and extraction method of the present invention, the total rhenium recovery rate can reach more than 99%, and finally an ammonium perrhenate product meeting the first-class product grade standard of YS / T894 - 2013 is produced, that is, the mass fraction of ammonium perrhenate reaches 99.9%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, purposes, and advantages of the present invention will become more obvious:

[0018] Figure 1 It is a flowchart of the method of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The following further describes the present invention in detail with reference to embodiments, but the embodiments of the present invention are not limited thereto.

[0020] Example 1

[0021] This example provides a method for separating and extracting rhenium from smelting waste acid, including the following steps:

[0022] S1. Add hydrogen peroxide with a mass concentration of 30% to the rhenium-containing waste acid generated from copper and molybdenum smelting. The addition amount is 10% of the total amount of waste acid. Then add Na2S to precipitate copper and molybdenum. The addition amount of Na2S is 10 g / L. Adjust the temperature of the waste acid to 50 °C, and use a stirrer to stir at a speed of 110 r / min for 10 min to mix evenly. After mixing, let it stand for 10 min to separate the mixed liquid into layers;

[0023] Among them, the purpose of adding hydrogen peroxide is: using the strong oxidizing property of hydrogen peroxide, all low-valent rhenium compounds in the waste acid are converted into soluble high-valent rhenium compounds, that is, HReO4. The specific reaction process is as follows:

[0024] Re2O7 + ReO2 + ReO3 + 2H2O2 = 2Re2O7 + 2H2O;

[0025] Re2O7 + H2O = 2HReO4;

[0026] The purpose of adding Na2S is: generating copper sulfide precipitate by the reaction of Na2S with copper ions, and achieving coprecipitation by the selective adsorption of molybdenum ions after the formation of copper sulfide, so as to remove the main impurities (i.e., copper ions and molybdenum ions) in the waste acid and obtain a rhenium-containing solution with higher purity.

[0027] S2. Extract the supernatant, add sulfuric acid to acidify it for 5 - 10 min to obtain an acidified solution. The addition amount of sulfuric acid is set to contain 5 wt% sulfuric acid in the supernatant to ensure that rhenium always exists in the form of soluble perrhenic acid during the extraction process, thereby ensuring the extraction effect.

[0028] S3. Extraction: Perform organic extraction on the acidified solution prepared in step S2. Use tri-n-octylamine (TOA) as the extractant, sec-octanol as the cosolvent, and kerosene as the diluent. Mix them evenly to make an extraction organic phase. Among them, the volume ratio of the extractant, cosolvent, and diluent is 1:1:3, and the volume ratio of the organic phase to the aqueous phase is O / A = 1 / 2; Mix and stir the acidified solution and the extraction organic phase at room temperature for 10 min, let it stand and separate into layers. The aqueous phase is discarded after harmless treatment;

[0029] Among them, the high-selectivity extraction mechanism of TOA for high-valent rhenium compounds is: TOA first combines with H+ in the aqueous phase, + then combines with perrhenate ions, and finally forms a stable ion-association complex, thereby transferring all high-valent rhenium compounds to the organic phase to complete efficient extraction.

[0030] S4, Back-extraction and regeneration: Take the extract in step S3, use ammonia water with a concentration of 7 mol / L as the back-extraction agent for back-extraction. Set the volume ratio of the extract to the back-extraction agent as O / A = 2 / 1. Mix and stir at room temperature for 20 min, let it stand for phase separation, and separate the phases at a phase flow rate of 1 L / min to obtain the back-extract, which is the ammonium perrhenate solution; Add sulfuric acid to the raffinate of the back-extraction and acidify for 5 min until the sulfuric acid content in the raffinate of the back-extraction reaches 5 wt%.

[0031] S5, Purification, condensation and crystallization: Cool and crystallize the back-extract in an environment at -10°C, perform vacuum filtration on the raffinate after crystallization, and take the crystals therein to obtain ammonium perrhenate solid powder.

[0032] Example 2

[0033] This example provides a method for separating and extracting rhenium from smelting waste acid. The difference from Example 1 lies in the specific process parameters. Specifically, it includes the following steps:

[0034] S1, Add hydrogen peroxide with a mass concentration of 30% to the rhenium-containing waste acid generated from copper and molybdenum smelting for oxidation. The addition amount is 10% of the total amount of waste acid, and add Na2S for copper precipitation and molybdenum precipitation. The addition amount of Na2S is 15 g / L. Adjust the temperature of the waste acid to 70°C, use a stirrer to stir at a speed of 130 r / min for 10 min for mixing and homogenization, let it stand for 10 min after homogenization to make the mixed solution separate into layers;

[0035] S2, Extract the supernatant, add sulfuric acid for acidification for 10 min to obtain the acidified solution. The addition amount of sulfuric acid is set to make the sulfuric acid content in the supernatant reach 7 wt%.

[0036] S3, Extraction: Perform organic extraction on the acidified solution prepared in step S2. Use tri-n-octylamine (TOA) as the extractant, sec-octanol as the co-solvent, and kerosene as the diluent. Mix them evenly to make the extraction organic phase. Among them, the volume ratio of the extractant, co-solvent and diluent is 1:1:3, and the volume ratio of the organic phase to the aqueous phase is O / A = 1 / 2; Mix and stir the acidified solution and the extraction organic phase at room temperature for 20 min, let it stand for phase separation, and discard the aqueous phase after harmless treatment;

[0037] S4, Back-extraction and regeneration: Take the extract in step S3, use ammonia water with a concentration of 7 mol / L as the back-extraction agent for back-extraction. Set the volume ratio of the extract to the back-extraction agent as O / A = 2 / 1. Mix and stir at room temperature for 20 min, let it stand for phase separation, and separate the phases at a phase flow rate of 1 L / min to obtain the back-extract, which is the ammonium perrhenate solution; Add sulfuric acid to the raffinate of the back-extraction and acidify for 5 min until the sulfuric acid content in the raffinate of the back-extraction reaches 5 wt%.

[0038] S6, Concentration and enrichment: Mix the stripping solutions obtained in batches according to step S4. After collecting a certain amount, conduct unified concentration and enrichment. First, heat the stripping solution at 30 - 40 °C to remove unreacted ammonia water, and then heat it at 90 - 100 °C to remove excess moisture, obtaining a rhenium-rich solution.

[0039] S5, Purification, condensation and crystallization: Cool and crystallize the rhenium-rich solution in an environment at 0 °C. Conduct vacuum filtration on the stripped residual solution after crystallization, and take the crystals therein to obtain ammonium perrhenate solid powder.

[0040] Through Example 1 and Example 2, ammonium perrhenate solid powder is obtained. Table 1 shows the measurement results of the samples detected respectively using the non-ferrous metal industry standard YS / T 902 - 2013. The results of this sample meet the first-class product grade standard of YS / T 894 - 2013, and the mass fraction of ammonium perrhenate reaches 99.90%.

[0041] Table 1 Measurement results of ammonium perrhenate samples

[0042]

[0043]

[0044] As mentioned above, it is only a preferred embodiment of the present invention, and does not impose any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for separating and extracting rhenium from smelting waste acid, characterized in that, It includes the following steps: S1. Add hydrogen peroxide with a mass concentration of 30% to the rhenium-containing waste acid generated from copper and molybdenum smelting. The addition amount is 10% of the total amount of waste acid. Then add Na2S to precipitate copper and molybdenum. The addition amount of Na2S is 10 - 15 g / L. Adjust the temperature of the waste acid to 50 - 70 °C, and use a stirrer to stir at a speed of 110 - 130 r / min for 5 - 10 min to mix evenly. After mixing, let it stand for 5 - 10 min to make the mixed solution stratified; S2. Extract the supernatant, add sulfuric acid to acidify it for 5 - 10 min to obtain an acidified solution. The addition amount of sulfuric acid is determined according to the sulfuric acid content of 5 - 7 wt% in the supernatant; S3. Extraction: Perform organic extraction on the acidified solution prepared in step S2. Use tri-n-octylamine as the extractant, sec-octanol as the co-solvent, and kerosene as the diluent. Mix them evenly to prepare an extraction organic phase. Among them, the volume ratio of the extractant, co-solvent, and diluent is 1:1:3, and the volume ratio of the organic phase to the aqueous phase is O / A = 1 / 2. Mix and stir the acidified solution and the extraction organic phase at room temperature for 10 - 20 min, let it stand and stratify. The aqueous phase is discarded after harmless treatment; S4. Back-extraction: Take the extraction phase in step S3, use ammonia water with a concentration of 7 mol / L as the back-extraction agent for back-extraction. Set the volume ratio of the extraction phase to the back-extraction agent as O / A = 2 / 1. Mix and stir at room temperature for 10 - 20 min, let it stand and stratify, and perform phase separation at a phase flow rate of 0.5 - 1 L / min to obtain a back-extraction solution, which is ammonium perrhenate solution; S5. Purification, condensation and crystallization: Place the back-extraction solution in an environment of -10 to 0 °C to cool and crystallize. Perform vacuum filtration on the back-extraction residue after crystallization, and take the crystals therein to obtain ammonium perrhenate solid powder.

2. The method for separating and extracting rhenium from smelting waste acid according to claim 1, wherein: Before step S5, it also includes S6. Concentration and enrichment: Mix the back-extraction solutions obtained in step S4 in batches. After collecting a certain amount, conduct concentration and enrichment uniformly. First, heat the back-extraction solution at 30 - 40 °C to remove the unreacted ammonia water, and then heat it at 90 - 100 °C to remove the surplus water to obtain a rhenium-rich solution; then perform the purification, condensation and crystallization of step S5 on the rhenium-rich solution.

3. A method for separating and extracting rhenium from smelting waste acid according to claim 1, characterized in that: Add sulfuric acid to acidify the back-extraction residue obtained in step S4 for 5 min. The addition amount of sulfuric acid is determined according to the sulfuric acid content of 5 - 7 wt% in the back-extraction residue.

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