Method for extracting molybdenum through complexing and reverse extraction

Abstract

The invention relates to a method for extracting molybdenum through complexation and reverse extraction, belongs to the field of non-ferrous metal hydrometallurgy, and solves the problems that ammonia nitrogen and sodium salt wastewater can be generated when molybdenum is extracted from an acid leaching solution through an extraction method in the prior art, and the environment is seriously polluted; the organic phase needs pickling regeneration, a large amount of acidic reagents are consumed, and the molybdenum extraction cost is increased; and the reverse extraction rate is low. The method comprises the following steps: extracting an acid leaching solution of molybdenum by using a cationic extractant at normal temperature, and separating after extraction to obtain a molybdenum-containing loaded organic phase and an acid raffinate; the molybdenum-containing loaded organic phase is subjected to back extraction with a back extraction agent containing oxalic acid, and an organic phase and molybdenum-enriched back extraction liquid are obtained through separation; and the reverse-extracted organic phase is used as an extracting agent to circularly extract molybdenum in the acid leaching solution. According to the method, the molybdenum-containing acidic leachate is extracted by using the cationic extractant at normal temperature, and the molybdenum-containing loaded organic phase is subjected to reverse extraction by using oxalic acid (or oxalic acid and hydrogen peroxide), so that the environment is optimized, and the reverse extraction rate of molybdenum is improved.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal hydrometallurgy, and in particular to a method for extracting molybdenum by complexation back-extraction. Background Technology

[0002] Molybdenum (Mo) is a rare refractory metal with significant industrial value, widely used in the steel, machinery, and petroleum industries, and global demand for molybdenum continues to increase. In molybdenum extraction processes, inorganic acid wet leaching is widely used due to its relatively low reagent consumption and environmental friendliness. After acid leaching, the molybdenum in the leachate still needs further extraction and enrichment. Solvent extraction, due to its simple process, high metal ion separation coefficient, and strong saturation capacity, has become the mainstream technology for molybdenum recovery and purification from acidic leachates.

[0003] In acid leaching solutions, molybdenum ions are mostly molybdenum acyl cations (Mo2O5). 2+ or MoO2 2+ The molybdenum(VI) exists stably in its current form. Since the extraction mechanism of cationic extractants, such as acidic phosphorus extractants, is primarily based on cation exchange, they can be used for the recovery and purification of molybdenum(VI) in acid leaching solutions. However, due to the strong binding force between the extractant and the molybdenum acyl cation, it is difficult to back-extract the molybdenum loaded in the organic phase into the aqueous solution, usually requiring extremely high concentrations of acid or complex processes for back-extraction.

[0004] Common methods involve increasing the alkalinity of the solution with ammonia or sodium hydroxide to convert molybdenum in the extract from a cationic form to an anionic form for back-extraction. To accelerate phase separation and prevent the formation of a third phase, ammonium salts are also added to the alkaline back-extraction system. However, these methods inevitably generate large amounts of ammonia nitrogen and sodium salt wastewater, leading to environmental pollution. Furthermore, the volatility of ammonia during back-extraction results in a poor working environment. Additionally, the extractant after back-extraction requires acid washing and regeneration, increasing the process burden and the cost of molybdenum extraction. Therefore, optimizing the efficient and environmentally friendly extraction of molybdenum from molybdenum-loaded cationic extractants has become an urgent problem to be solved. Summary of the Invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide a method for extracting molybdenum by complexation back-extraction, at least to solve one of the following problems: 1. Existing methods for extracting molybdenum from acidic leachates generate a large amount of ammonia nitrogen and sodium salt wastewater during the back-extraction process, causing serious environmental pollution; 2. Existing methods for extracting molybdenum from acidic leachates require an acid washing and regeneration step for the organic phase after alkaline back-extraction, consuming a large amount of acidic reagents, increasing the process burden and the cost of molybdenum extraction; 3. Existing methods for extracting molybdenum from acidic leachates have a low back-extraction rate.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] This invention provides a method for extracting molybdenum by complexation and back-extraction, comprising the following steps:

[0008] A method for extracting molybdenum by complexation and back-extraction includes the following steps:

[0009] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature, and the molybdenum-supported organic phase and acidic raffinate are separated after extraction.

[0010] S2: The molybdenum-supported organic phase described in S1 is back-extracted using a complexing back-extracting agent to separate the organic phase and the molybdenum-enriched back-extracting solution;

[0011] S3: Use the organic phase described in S2 as a cationic extractant to perform cyclic extraction of molybdenum in the acidic leachate in S1;

[0012] In step S2, the complexing stripping agent includes oxalic acid.

[0013] Further, in step S1, the cationic extractant is one or more of acidic phosphorus extractants, carboxylic acid extractants, and oxime chelating extractants.

[0014] Further, in step S1, the volume fraction of the cationic extractant in the organic phase is 10% to 50%.

[0015] Furthermore, in step S1, the extraction method is multi-stage countercurrent extraction, with 2 to 5 extraction stages.

[0016] Furthermore, in step S1, during the extraction process, the volume ratio of the organic phase to the aqueous phase (O / A) is 1:5 to 5:1, the extraction temperature is 10 to 50°C, and the single-stage extraction time is 5 to 20 minutes.

[0017] Further, in step S2, the concentration of oxalic acid is 0.01–1 mol / L.

[0018] Furthermore, in step S2, the back-extraction method is multi-stage countercurrent extraction, with 3 to 8 back-extraction stages.

[0019] Furthermore, in step S2, during the back-extraction process, the volume ratio of the organic phase to the aqueous phase (O / A) is 1:7 to 4:1, the back-extraction temperature is 30 to 60°C, and the single-stage back-extraction time is 5 to 20 minutes.

[0020] Further, in step S1, the settling time for the extracted organic phase and aqueous phase to separate is 10-20 min; in step S2, the settling time for the back-extracted organic phase and aqueous phase to separate is 10-20 min.

[0021] Further, in step S2, the complexing stripping agent is oxalic acid and hydrogen peroxide.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] 1. This invention utilizes the different forms of molybdenum in different environments by extracting molybdenum-containing acidic leachate with a cationic extractant at room temperature and then back-extracting the molybdenum-loaded organic phase with a complexing extractant containing oxalic acid. This simple extraction process efficiently recovers molybdenum from the acidic leachate, achieving a molybdenum recovery rate of ≥99%. At the same time, it avoids the use of strong alkalis and the discharge of ammonia nitrogen wastewater in molybdenum metallurgy, improves the working environment, reduces environmental pollution, and is more environmentally friendly.

[0024] 2. This invention utilizes an oxalic acid-containing back-extraction agent to remove molybdenum acyl cations (MoO2) from the extract. 2+ In acidic solution, it reacts with oxalate (C2O4) 2- The molybdenum acyl cation forms a complex anion. Since the complex formed by the molybdenum acyl cation and oxalic acid is more stable than the complex formed with the cationic extractant, the molybdenum acyl cation in the molybdenum-supported organic phase can be back-extracted into the aqueous solution through oxalic acid to obtain a back-extracting solution enriched with molybdenum. This effectively solves the problem of difficulty in back-extracting molybdenum from the extractant due to the strong binding force between Mo(VI) and the extractant in the existing process. Compared with the high concentration of inorganic acid back-extractants used in industry, the use of back-extractants containing oxalic acid reduces reagent consumption and improves the back-extraction rate of molybdenum.

[0025] 3. This invention uses an oxalic acid-containing back-extraction agent, which has more advantages than the alkaline method (ammonia or sodium hydroxide) back-extraction. First, using oxalic acid as a reducing agent reduces the generation of a large amount of ammonia nitrogen wastewater and sodium salt wastewater, improves the working environment, and is more environmentally friendly. At the same time, oxalic acid is a moderately strong acid, and the cationic extractant obtained after back-extraction can be reused without acid treatment and regeneration, and can be directly used for cyclic extraction, which is simple to operate.

[0026] 4. In this invention, a back-extraction agent containing oxalic acid and hydrogen peroxide (H2O2) can also be used. Both oxalic acid and hydrogen peroxide (H2O2) are effective acidic complexing agents that can effectively complex with molybdenum ions in the cationic organic phase to achieve back-extraction.

[0027] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0028] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0029] Figure 1 This is a process flow diagram of the complexation back-extraction extraction of molybdenum according to the present invention. Detailed Implementation

[0030] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0031] This invention provides a method for extracting molybdenum by complexation and back-extraction, comprising the following steps:

[0032] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature, and the molybdenum-supported organic phase and acidic raffinate are separated after extraction.

[0033] S2: The molybdenum-supported organic phase described in S1 is back-extracted with oxalic acid to separate the cationic organic phase and the molybdenum-enriched back-extraction solution;

[0034] S3: The organic phase described in S2 is used as a cationic extractant to perform cyclic extraction of molybdenum in the acidic leachate in S1.

[0035] Specifically, in step S1, the molybdenum-containing acidic leachate preferably has a molybdenum ion concentration of 10 g / L-50 g / L, and the leaching agent used is one or more of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid; the cationic extractant is one or a combination of acidic phosphoric acid extractants, carboxylic acid extractants, and oxime chelating extractants. During the extraction process, kerosene is used as the diluent, and the volume fraction of the extractant in the organic phase is 10%-50%, preferably 30%-40%. Increasing the extractant concentration can effectively improve the activity of the interface between the aqueous and organic phases, accelerate the transfer and equilibrium of molybdenum ions, and improve the extraction efficiency. The above-mentioned volume fraction of extractant can achieve sufficient extraction of molybdenum acyl cations.

[0036] The volume ratio of organic phase to aqueous phase (O / A) is 1:5 to 5:1, preferably 2:1 to 4:1; the extraction temperature is 10 to 50°C, preferably 15 to 30°C; the single-stage extraction time is 5 to 20 min, preferably 5 to 10 min. The extraction method is multi-stage countercurrent extraction, with 2 to 5 extraction stages, and the molybdenum extraction rate is ≥99%.

[0037] It should be noted that increasing the O / A ratio increases the contact area between the aqueous and organic phases, improving the interphase mass transfer rate and promoting the extraction process. However, an excessively high O / A ratio can lead to waste of organic reagents. Increasing the extraction temperature helps promote the interphase mass transfer rate and reduce the viscosity of the extractant, thereby improving extraction efficiency. However, considering that the extraction of molybdenum acyl cations by the cationic extractant is an exothermic reaction, it is necessary to control the extraction temperature appropriately. Increasing the single-stage extraction time allows for more complete molybdenum ion transfer and diffusion, thus improving extraction efficiency. The above-mentioned O / A ratio, extraction temperature, and extraction time can ensure the complete and efficient extraction of molybdenum acyl cations.

[0038] Specifically, in step S2, the stripping agent includes oxalic acid (H2C2O4), and the diluent is pure water. The stripping agent needs to be diluted to a concentration of 0.01–1 mol / L, preferably 0.5–0.8 mol / L; the volume ratio of the organic phase to the aqueous phase (O / A) is 1:7–4:1, preferably 1:2–3:1; the stripping temperature is 30–60℃, preferably 45–55℃; and the single-stage stripping time is 5–20 min, preferably 10–15 min. The stripping method is multi-stage countercurrent extraction, with 3–8 stripping stages, and the stripping rate of molybdenum is ≥99%.

[0039] It should be noted that increasing the stripping agent concentration and decreasing the stripping ratio O / A will increase the relative content of the stripping agent, leading to a higher molybdenum stripping rate. However, excessively high stripping agent concentration and excessively low stripping ratio O / A will result in waste of stripping agent. Increasing the stripping temperature helps to promote the mass transfer rate and reduce the viscosity of the organic phase, thereby improving the molybdenum stripping efficiency. However, excessively high temperatures will also lead to increased energy consumption, so it is necessary to control the appropriate stripping temperature. Increasing the stripping time allows for more complete molybdenum ion transfer and diffusion, thereby improving the stripping efficiency. Under the conditions of the stripping agent concentration, stripping ratio O / A, stripping temperature, time, and countercurrent stage, it can be ensured that the molybdenum ions loaded in the organic cationic extractant can be fully and efficiently stripped.

[0040] By using a back-extraction agent containing oxalic acid, the molybdenum acyl cation (MoO2) in the extract is removed. 2+ In acidic solution, it reacts with oxalate (C2O4) 2-The molybdenum acyl cations form complex anions. Since the complexes formed by molybdenum acyl cations and oxalic acid are more stable than those formed with cationic extractants, the molybdenum acyl cations in the molybdenum-loaded organic phase can be back-extracted into the aqueous solution via oxalic acid, yielding a molybdenum-enriched back-extractant. This effectively solves the problem of Mo(VI) being difficult to back-extract from cationic extractants due to their strong binding force. Furthermore, oxalic acid is a moderately strong acid, and the resulting cationic organic phase after back-extraction is an acidic cationic extractant, which can be reused without acid treatment and regeneration, directly used for cyclic extraction, simplifying the operation.

[0041] It should be noted that during the extraction and back-extraction processes, the settling time for both the organic and aqueous phases is 10–20 min.

[0042] It should be noted that in step S2, the present invention can also use a back-extraction agent containing oxalic acid and hydrogen peroxide (H2O2), wherein both oxalic acid and hydrogen peroxide (H2O2) are acidic complexing agents, which can effectively complex with molybdenum ions in the cationic organic phase to achieve back-extraction. In the back-extraction operation, the back-extraction agent oxalic acid (H2C2O4) needs to be diluted to a concentration of 0.01–1 mol / L, preferably 0.5–0.8 mol / L; the back-extraction agent hydrogen peroxide (H2O2) needs to be diluted to 0.5–5 mol / L, preferably 1–3 mol / L; the volume ratio of the organic phase to the aqueous phase O / A = 1:7–3:1, preferably O / A = 1:2–3:1; the back-extraction temperature is 30–40℃; the single-stage back-extraction time is 5–20 min, preferably 10–15 min. The back-extraction method is multi-stage countercurrent extraction, with 4–8 back-extraction stages, and the molybdenum back-extraction rate is ≥99%.

[0043] Specifically, in S3, the organic phase described in S2 is used as a cationic extractant to circulate and extract molybdenum from the acidic leachate in S1. The extraction conditions are the same as in S1, and the extraction rate of molybdenum is ≥99%.

[0044] This invention utilizes the different forms of molybdenum existing under varying conditions to efficiently recover molybdenum from the acidic leachate of molybdenum calcined ore at room temperature using a cationic extractant. The extraction process avoids the use of strong alkalis and the discharge of ammonia nitrogen wastewater during molybdenum metallurgy, improving the working environment, reducing environmental pollution, and making it more environmentally friendly. Furthermore, by employing a back-extraction agent containing oxalic acid (or oxalic acid + hydrogen peroxide), the molybdenum acyl cations (MoO2) in the extract are removed. 2+The formation of complex anions in acidic solutions effectively solves the problem of Mo(VI) having a strong binding force with the cationic extractant, making it difficult to back-extract in existing processes for back-extracting molybdenum from cationic extractants. Compared with high-concentration inorganic acid back-extractants used in industry, the use of back-extractants containing oxalic acid (or oxalic acid + hydrogen peroxide) reduces reagent consumption and increases the back-extraction rate of molybdenum. At the same time, oxalic acid is a moderately strong acid, and the acidic cationic extractant obtained after back-extraction can be reused without acid treatment and regeneration, making the operation simple.

[0045] Example 1

[0046] This embodiment provides a method for extracting molybdenum by complexation and back-extraction, including the following steps:

[0047] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature to separate the molybdenum-supported organic phase and the acidic raffinate.

[0048] In the molybdenum-containing acidic leachate, the molybdenum ion concentration is 20 g / L, the leachate is a mixed acid solution of sulfuric acid and phosphoric acid, and the extractant is organic cationic extractant P507, which has a volume fraction of 40% in the organic phase.

[0049] The extraction was a two-stage countercurrent extraction, with kerosene as the diluent. The volume ratio of the organic phase to the aqueous phase was O / A = 2:1. The extraction temperature was 20℃, and the single-stage extraction time was 10 min. After extraction, the organic and aqueous phases were separated by allowing the mixture to stand for 10 min. The molybdenum concentration in the raffinate was measured, and the molybdenum extraction rate was calculated to be 99.2%.

[0050] S2: The molybdenum-supported organic phase in S1 is back-extracted with oxalic acid to separate the cationic organic phase and the molybdenum-enriched back-extraction solution.

[0051] The back-extraction process consisted of a 6-stage countercurrent back-extraction, with an oxalic acid (H2C2O4) concentration of 0.8 mol / L and pure water as the diluent. During the back-extraction process, the volume ratio of the organic phase to the aqueous phase was O / A = 3:1, the back-extraction temperature was 50℃, and the single-stage back-extraction time was 10 min. After the back-extraction was completed, the mixture was allowed to stand for 10 min for phase separation. The molybdenum concentration in the back-extraction solution was measured, and the molybdenum back-extraction rate was calculated to be 99.1%.

[0052] S3: The organic phase containing P507 after back-extraction in S2 is used for cyclic extraction in S1. After two stages of countercurrent extraction, the extraction rate of molybdenum is 99.1%.

[0053] Example 2

[0054] This embodiment provides a method for extracting molybdenum by complexation and back-extraction, including the following steps:

[0055] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature to separate the molybdenum-supported organic phase and the acidic raffinate.

[0056] In the molybdenum-containing acidic leachate, the molybdenum ion concentration is 20 g / L, the leachate is a mixed acid solution of sulfuric acid and phosphoric acid, and the extractant is an organic cationic extractant P204, which has a volume fraction of 40% in the organic phase.

[0057] The extraction was performed using a three-stage countercurrent extraction method. Kerosene was used as the diluent during extraction; the volume ratio of the organic phase to the aqueous phase (O / A) was 3:1; the extraction temperature was 25℃; and the single-stage extraction time was 10 min. After extraction, the mixture was allowed to stand for 10 min to separate the organic and aqueous phases. The molybdenum concentration in the raffinate was measured, and the molybdenum extraction rate was calculated to be 99.4%.

[0058] S2: The molybdenum-supported organic phase in S1 is back-extracted with oxalic acid to separate the cationic organic phase and the molybdenum-enriched back-extraction solution.

[0059] The back-extraction process consisted of 5 stages of countercurrent back-extraction, with an oxalic acid (H2C2O4) concentration of 0.8 mol / L and pure water as the diluent. During the back-extraction process, the volume ratio of the organic phase to the aqueous phase was O / A = 2:1, the back-extraction temperature was 50℃, and the single-stage back-extraction time was 10 min. After the back-extraction was completed, the mixture was allowed to stand for 10 min for phase separation. The molybdenum concentration in the back-extraction solution was measured, and the molybdenum back-extraction rate was calculated to be 99%.

[0060] S3: The organic phase containing P2O4 after back-extraction in S2 is used for cyclic extraction in S1. After three stages of countercurrent extraction, the extraction rate of molybdenum is 99.2%.

[0061] Example 3

[0062] This embodiment provides a method for extracting molybdenum by complexation and back-extraction, including the following steps:

[0063] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature to separate the molybdenum-supported organic phase and the acidic raffinate.

[0064] In the molybdenum-containing acidic leachate, the molybdenum ion concentration is 20 g / L, the leachate is a mixed acid solution of sulfuric acid and phosphoric acid, and the extractant is organic cationic extractant P507, which has a volume fraction of 30% in the organic phase.

[0065] The extraction was performed using a 5-stage countercurrent extraction method. Kerosene was used as the diluent during extraction; the volume ratio of the organic phase to the aqueous phase was 3:1 (O / A); the extraction temperature was 25℃; and the single-stage extraction time was 5 min. After extraction, the organic and aqueous phases were separated by allowing the mixture to stand for 5 min. The molybdenum concentration in the raffinate was measured, and the molybdenum extraction rate was calculated to be 99.1%.

[0066] S2: The molybdenum-supported organic phase in S1 is back-extracted with oxalic acid to separate the cationic organic phase and the molybdenum-enriched back-extraction solution.

[0067] The back-extraction process consisted of a 6-stage countercurrent back-extraction, with an oxalic acid (H2C2O4) concentration of 0.6 mol / L and pure water as the diluent. During the back-extraction process, the volume ratio of the organic phase to the aqueous phase was 1:1 (O / A = 1:1), the back-extraction temperature was 60℃, and the single-stage back-extraction time was 15 min. After the back-extraction was completed, the mixture was allowed to stand for 10 min for phase separation. The molybdenum concentration in the back-extraction solution was measured, and the molybdenum back-extraction rate was calculated to be 99%.

[0068] S3: The organic phase containing P507 after back-extraction in S2 is used for cyclic extraction in S1. After three stages of countercurrent extraction, the extraction rate of molybdenum is 99%.

[0069] Example 4

[0070] This embodiment provides a method for extracting molybdenum by complexation and back-extraction, including the following steps:

[0071] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature to separate the molybdenum-supported organic phase and the acidic raffinate.

[0072] In the molybdenum-containing acidic leachate, the molybdenum ion concentration is 20 g / L, the leachate is a mixed acid solution of sulfuric acid and phosphoric acid, and the extractant is organic cationic extractant P507, which has a volume fraction of 40% in the organic phase.

[0073] The extraction was a single-stage countercurrent extraction, with kerosene as the diluent; the volume ratio of organic phase to aqueous phase was O / A = 3:1; the extraction temperature was 20℃; and the single-stage extraction time was 10 min. After extraction, the organic and aqueous phases were separated by allowing the mixture to stand for 10 min. The molybdenum concentration in the raffinate was measured, and the molybdenum extraction rate was calculated to be 99.4%.

[0074] S2: The molybdenum-supported organic phase in S1 is back-extracted with oxalic acid to separate the cationic organic phase and the molybdenum-enriched back-extraction solution.

[0075] The back-extraction process consisted of 5 stages of countercurrent back-extraction, with oxalic acid (H2C2O4) concentration of 0.8 mol / L and pure water as the diluent. During the back-extraction process, the volume ratio of the organic phase to the aqueous phase was O / A = 1:1, the back-extraction temperature was 50℃, and the single-stage back-extraction time was 15 min. After the back-extraction was completed, the mixture was allowed to stand for 10 min for phase separation. The molybdenum concentration in the back-extraction solution was measured, and the molybdenum back-extraction rate was calculated to be 99.2%.

[0076] S3: The organic phase containing P507 after back-extraction in S2 is used for cyclic extraction in S1. After three stages of countercurrent extraction, the extraction rate of molybdenum is 99%.

[0077] Example 5

[0078] This embodiment provides a method for extracting molybdenum by complexation back-extraction, wherein the back-extraction agents are oxalic acid and hydrogen peroxide (H2O2), and includes the following steps:

[0079] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature to separate the molybdenum-supported organic phase and the acidic raffinate.

[0080] In the molybdenum-containing acidic leachate, the molybdenum ion concentration is 20 g / L, the leachate is a mixed acid solution of sulfuric acid and phosphoric acid, and the extractant is organic cationic extractant P507, which has a volume fraction of 40% in the organic phase.

[0081] The extraction was a two-stage countercurrent extraction, with kerosene as the diluent. The volume ratio of the organic phase to the aqueous phase was O / A = 2:1. The extraction temperature was 20℃, and the single-stage extraction time was 10 min. After extraction, the organic and aqueous phases were separated by allowing the mixture to stand for 10 min. The molybdenum concentration in the raffinate was measured, and the molybdenum extraction rate was calculated to be 99.2%.

[0082] S2: The molybdenum-supported organic phase in S1 is back-extracted with oxalic acid and hydrogen peroxide (H2O2) to separate the cationic organic phase and the molybdenum-enriched back-extraction solution.

[0083] The back-extraction process consisted of a 6-stage countercurrent back-extraction, using oxalic acid and hydrogen peroxide (H2O2) as the back-extraction agents. The concentration of oxalic acid (H2C2O4) was 0.4 mol / L, and the concentration of hydrogen peroxide (H2O2) was 1 mol / L. The diluent was pure water. During the back-extraction process, the volume ratio of the organic phase to the aqueous phase was 3:1 (O / A = 3:1), the back-extraction temperature was 35℃, and the single-stage back-extraction time was 10 min. After the back-extraction was completed, the mixture was allowed to stand for 10 min for phase separation. The molybdenum concentration in the back-extraction solution was measured, and the molybdenum back-extraction rate was calculated to be 99.4%.

[0084] S3: The organic phase containing P507 after back-extraction in S2 is used for cyclic extraction in S1. After three stages of countercurrent extraction, the extraction rate of molybdenum is 99.2%.

[0085] Example 6

[0086] This embodiment provides a method for extracting molybdenum by complexation and back-extraction, including the following steps:

[0087] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature to separate the molybdenum-supported organic phase and the acidic raffinate.

[0088] In the molybdenum-containing acidic leachate, the molybdenum ion concentration is 10 g / L, the leachate is a mixed acid solution of sulfuric acid and phosphoric acid, and the extractant is organic cationic extractant P507, which has a volume fraction of 20% in the organic phase.

[0089] The extraction was a two-stage countercurrent extraction, with kerosene as the diluent. The volume ratio of the organic phase to the aqueous phase was 2:1 (O / A). The extraction temperature was 20℃, and the single-stage extraction time was 10 min. After extraction, the organic and aqueous phases were separated by allowing the mixture to stand for 10 min. The molybdenum concentration in the raffinate was measured, and the molybdenum extraction rate was calculated to be 99.5%.

[0090] S2: The molybdenum-supported organic phase in S1 is back-extracted with oxalic acid to separate the cationic organic phase and the molybdenum-enriched back-extraction solution.

[0091] The back-extraction process consisted of three stages of countercurrent back-extraction, with oxalic acid (H2C2O4) concentration of 0.8 mol / L and pure water as the diluent. During the back-extraction process, the volume ratio of the organic phase to the aqueous phase was O / A = 3:1, the back-extraction temperature was 50℃, and the single-stage back-extraction time was 10 min. After the back-extraction was completed, the mixture was allowed to stand for 10 min for phase separation. The molybdenum concentration in the back-extraction solution was measured, and the molybdenum back-extraction rate was calculated to be 99.2%.

[0092] S3: The organic phase containing P507 after back-extraction in S2 is used for cyclic extraction in S1. After two stages of countercurrent extraction, the extraction rate of molybdenum is 99.2%.

[0093] Example 7

[0094] This embodiment provides a method for extracting molybdenum by complexation and back-extraction, including the following steps:

[0095] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature to separate the molybdenum-supported organic phase and the acidic raffinate.

[0096] In the molybdenum-containing acidic leachate, the molybdenum ion concentration is 45 g / L, the leachate is a mixed acid solution of sulfuric acid and phosphoric acid, and the extractant is organic cationic extractant P507, which has a volume fraction of 40% in the organic phase.

[0097] The extraction was a two-stage countercurrent extraction, with kerosene as the diluent. The volume ratio of the organic phase to the aqueous phase was 3:1 (O / A). The extraction temperature was 20℃, and the single-stage extraction time was 10 min. After extraction, the organic and aqueous phases were separated by allowing the mixture to stand for 10 min. The molybdenum concentration in the raffinate was measured, and the molybdenum extraction rate was calculated to be 99.1%.

[0098] S2: The molybdenum-supported organic phase in S1 is back-extracted with oxalic acid to separate the cationic organic phase and the molybdenum-enriched back-extraction solution.

[0099] The back-extraction process consisted of a 6-stage countercurrent back-extraction, with an oxalic acid (H2C2O4) concentration of 0.8 mol / L and pure water as the diluent. During the back-extraction process, the volume ratio of the organic phase to the aqueous phase was O / A = 4:1, the back-extraction temperature was 50℃, and the single-stage back-extraction time was 10 min. After the back-extraction was completed, the mixture was allowed to stand for 10 min for phase separation. The molybdenum concentration in the back-extraction solution was measured, and the molybdenum back-extraction rate was calculated to be 99%.

[0100] S3: The organic phase containing P507 after back-extraction in S2 is used for cyclic extraction in S1. After two stages of countercurrent extraction, the extraction rate of molybdenum is 99.1%.

[0101] Comparative Example 1

[0102] This comparative example provides a method for extracting molybdenum by complexation back-extraction, comprising the following steps:

[0103] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature to separate the molybdenum-supported organic phase and the acidic raffinate.

[0104] In the acidic leachate of molybdenum calcined sand, the molybdenum ion concentration is 20 g / L, the leachate is a mixed acid solution of sulfuric acid and phosphoric acid, and the extractant is organic cationic extractant P507, which has a volume fraction of 40% in the organic phase.

[0105] The extraction was a two-stage countercurrent extraction. Kerosene was used as the diluent, and the volume ratio of the organic phase to the aqueous phase was 3:1 (O / A). The extraction temperature was 20℃, and the single-stage extraction time was 10 min. After extraction, the mixture was allowed to stand for 10 min to separate the organic and aqueous phases. The molybdenum concentration in the raffinate was measured, and the molybdenum extraction rate was calculated to be 99.2%.

[0106] S2: The molybdenum-supported organic phase in S1 is back-extracted with hydrochloric acid to separate the cationic organic phase and the molybdenum-enriched back-extraction solution.

[0107] The back-extraction was a single-stage countercurrent extraction with a hydrochloric acid (HCl) concentration of 6 mol / L and pure water as the diluent. During the back-extraction process, the volume ratio of the organic phase to the aqueous phase was 1:1 (O / A = 1:1), the back-extraction temperature was 30℃, and the single-stage back-extraction time was 10 min. After the back-extraction was completed, the mixture was allowed to stand for 10 min for phase separation. The molybdenum concentration in the back-extraction solution was measured, and the molybdenum back-extraction rate was calculated to be 21.1%, indicating a poor back-extraction effect and a large consumption of inorganic acid reagents.

[0108] Comparative Example 2

[0109] This comparative example provides a method for extracting molybdenum by complexation back-extraction, comprising the following steps:

[0110] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature to separate the molybdenum-supported organic phase and the acidic raffinate.

[0111] In the acidic leachate of molybdenum calcined sand, the molybdenum ion concentration is 20 g / L, the leachate is a mixed acid solution of sulfuric acid and phosphoric acid, and the extractant is organic cationic extractant P507, which has a volume fraction of 40% in the organic phase.

[0112] The extraction was a two-stage countercurrent extraction. Kerosene was used as the diluent, and the volume ratio of the organic phase to the aqueous phase was 3:1 (O / A). The extraction temperature was 20℃, and the single-stage extraction time was 10 min. After extraction, the mixture was allowed to stand for 10 min to separate the organic and aqueous phases. The molybdenum concentration in the raffinate was measured, and the molybdenum extraction rate was calculated to be 99.2%.

[0113] S2: The molybdenum-supported organic phase in S1 is back-extracted with a mixed solution of NH3 + NH4Cl to separate the cationic organic phase and the back-extraction solution enriched with molybdenum.

[0114] The back-extraction was a single-stage countercurrent extraction, with a 0.5 mol / L NH3 + 0.5 mol / L NH4Cl solution as the back-extraction agent and pure water as the diluent. During the back-extraction process, the volume ratio of the organic phase to the aqueous phase was 1:1 (O / A = 1:1), the back-extraction temperature was 30℃, and the single-stage extraction time was 10 min. After the back-extraction was completed, the mixture was allowed to stand for 10 min for phase separation. The molybdenum concentration in the back-extraction solution was detected, and the molybdenum back-extraction rate was calculated to be 81.1%, indicating a good back-extraction effect. However, it generated a large amount of ammonia nitrogen wastewater, which is environmentally unfriendly.

[0115] Comparative Example 3

[0116] This comparative example provides a method for extracting molybdenum by complexation back-extraction, comprising the following steps:

[0117] S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature to separate the molybdenum-supported organic phase and the acidic raffinate.

[0118] In the molybdenum-containing acidic leachate, the molybdenum ion concentration is 20 g / L, the leachate is a mixed acid solution of sulfuric acid and phosphoric acid, and the extractant is organic cationic extractant P507, which has a volume fraction of 20% in the organic phase.

[0119] The extraction was a two-stage countercurrent extraction, with kerosene as the diluent. The volume ratio of the organic phase to the aqueous phase was 2:1 (O / A). The extraction temperature was 20℃, and the single-stage extraction time was 10 min. After extraction, the organic and aqueous phases were separated by allowing the mixture to stand for 10 min. The molybdenum concentration in the raffinate was measured, and the molybdenum extraction rate was calculated to be 78.2%.

[0120] S2: The molybdenum-supported organic phase in S1 is back-extracted with oxalic acid to separate the cationic organic phase and the molybdenum-enriched back-extraction solution.

[0121] The back-extraction process consisted of a 6-stage countercurrent back-extraction, with an oxalic acid (H2C2O4) concentration of 0.4 mol / L and pure water as the diluent. During the back-extraction process, the volume ratio of the organic phase to the aqueous phase was 3:1 (O / A), the back-extraction temperature was 20℃, and the single-stage back-extraction time was 10 min. After the back-extraction was completed, the mixture was allowed to stand for 10 min for phase separation. The molybdenum concentration in the back-extraction solution was measured, and the molybdenum back-extraction rate was calculated to be 62.1%.

[0122] S3: The P507 organic phase after back-extraction in S2 is used for cyclic extraction in S1. After two stages of countercurrent extraction, the extraction rate of molybdenum is 73.1%.

[0123] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for extracting molybdenum by complexation and back-extraction, characterized in that, Includes the following steps: S1: The molybdenum-containing acidic leachate is extracted with a cationic extractant at room temperature, and the molybdenum-supported organic phase and acidic raffinate are separated after extraction. S2: The molybdenum-supported organic phase described in S1 is back-extracted using a complexing back-extracting agent to separate the organic phase and the molybdenum-enriched back-extracting solution; S3: Use the organic phase described in S2 as a cationic extractant to perform cyclic extraction of molybdenum in the acidic leachate in S1; In step S2, the complexing stripping agent includes oxalic acid.

2. The method for extracting molybdenum by complexation back-extraction according to claim 1, characterized in that, In step S1, the cationic extractant is one or more of acidic phosphorus extractants, carboxylic acid extractants, and oxime chelating extractants.

3. The method for extracting molybdenum by complexation and back-extraction according to claim 2, characterized in that, In step S1, the volume fraction of the cationic extractant in the organic phase is 10% to 50%.

4. The method for extracting molybdenum by complexation back-extraction according to claim 3, characterized in that, In step S1, the extraction method is multi-stage countercurrent extraction, with 2 to 5 extraction stages.

5. The method for extracting molybdenum by complexation back-extraction according to claim 4, characterized in that, In step S1, during the extraction process, the volume ratio of the organic phase to the aqueous phase (O / A) is 1:5 to 5:1, the extraction temperature is 10 to 50°C, and the single-stage extraction time is 5 to 20 minutes.

6. The method for extracting molybdenum by complexation back-extraction according to claim 1, characterized in that, In step S2, the concentration of oxalic acid is 0.01 to 1 mol / L.

7. The method for extracting molybdenum by complexation back-extraction according to claim 6, characterized in that, In step S2, the back-extraction method is multi-stage countercurrent extraction, with 3 to 8 back-extraction stages.

8. The method for extracting molybdenum by complexation back-extraction according to claim 7, characterized in that, In step S2, during the back-extraction process, the volume ratio of the organic phase to the aqueous phase (O / A) is 1:7 to 4:1, the back-extraction temperature is 30 to 60°C, and the single-stage back-extraction time is 5 to 20 minutes.

9. The method for extracting molybdenum by complexation back-extraction according to claim 1, characterized in that, In step S1, the settling time for the extracted organic phase and aqueous phase to separate is 10-20 min; in step S2, the settling time for the back-extracted organic phase and aqueous phase to separate is 10-20 min.

10. The method for extracting molybdenum by complexation back-extraction according to claim 1, characterized in that, In step S2, the complexing stripping agent is oxalic acid and hydrogen peroxide.

Images