Alkali leaching synergistic extraction recovery process for molybdenum in molybdenum concentrate

Abstract

The invention discloses an alkaline leaching synergistic extraction recovery process for molybdenum in molybdenum concentrate, and belongs to the technical field of hydrometallurgy. The molybdenum concentrate and 45-55 g / L sulfuric acid are subjected to size mixing according to the solid-to-liquid ratio of 1: (3-7), the temperature is increased to 180-250 DEG C, the oxygen partial pressure is adjusted to 0.5-1.5 MPa, cooling, filtering and washing are conducted after the reaction is conducted for 1.5-2.5 h, and acid leaching liquid and acid leaching residues are obtained. Mixing the acid leaching residues with 3-6mol / L ammonia water according to a solid-to-liquid ratio of 1: (2-5), reacting for 0.5-1.5 hours at the temperature of 25-80 DEG C, filtering and washing to obtain alkaline leaching liquid and alkaline leaching residues; mixing the pickle liquor with an extracting agent according to a phase ratio O / A of 1: (1-4), extracting, and splitting phases to obtain a molybdenum-loaded organic phase and raffinate; the molybdenum-loaded organic phase and 7-9 mol / L ammonia water are mixed according to the phase ratio O / A = (1-4): 1, phase splitting is conducted after extraction, and back-extracted liquid and an extracted organic phase are obtained; and mixing the back extraction solution with the alkaline leaching solution, heating to supersaturate ammonium molybdate, stopping heating when crystallization is started, precipitating crystals, filtering, washing, drying, and calcining at 540-560 DEG C for 1.5-2.5 hours. The method adopts a synergistic recovery process of alkaline leaching and extraction, the process flow is simplified, the energy consumption and reagent cost are low, the recovery rate and purity of molybdenum are improved, and the environmental protection property of the process is enhanced.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to a process for the alkaline leaching and synergistic extraction and recovery of molybdenum from molybdenum concentrate. Background Technology

[0002] Molybdenum, a rare refractory metal, has wide applications and significant strategic importance in high-end manufacturing, particularly in new energy and biomedicine. This necessitates higher requirements for the purity and functional properties of molybdenum products, driving the urgent development of molybdenum concentrate separation and extraction technology towards higher purification, refinement, and green practices. While traditional pyrometallurgical roasting processes are technically mature and highly adaptable, they suffer from several insurmountable drawbacks, such as severe pollution, high energy consumption, and product quality issues. Hydrometallurgical technology, as an important alternative to traditional pyrometallurgy, has been widely used in molybdenum concentrate separation and purification, but it also faces bottlenecks such as high chemical reagent consumption, high operating costs, and complex process flows. Therefore, there is an urgent need to develop a new process for the separation and recovery of molybdenum from molybdenum concentrate that consumes less reagent, reduces costs, simplifies the process flow, significantly improves recovery rate and purity, and enhances environmental friendliness, providing an efficient and clean solution for the recycling and utilization of molybdenum resources. Summary of the Invention

[0003] The purpose of this invention is to provide a process for the alkaline leaching and synergistic extraction and recovery of molybdenum from molybdenum concentrate.

[0004] The objective of this invention is achieved by the alkaline leaching and synergistic extraction recovery process for molybdenum in the molybdenum concentrate, comprising the following steps: Oxygen-pressure acid leaching: Molybdenum concentrate is mixed with 45-55 g / L sulfuric acid at a solid-liquid ratio of 1:3-7 to form a slurry. Under closed conditions, the mixture is stirred and heated to 180-250℃. When the temperature reaches the set value, the oxygen partial pressure is adjusted to 0.5-1.5 MPa. After reacting for 1.5-2.5 hours, the mixture is cooled. The leached material is then filtered and washed to obtain acid leaching solution and acid leaching residue. Alkali leaching: The acid leaching residue is mixed with 3-6 mol / L ammonia water at a solid-liquid ratio of 1:2-5, the temperature is adjusted to 25-80℃, and the mixture is stirred for 0.5-1.5 hours. The leached material is then filtered and washed to obtain alkaline leaching solution and alkaline leaching residue. Extraction: The acid leaching solution and the extractant were mixed at a ratio of O / A = 1:1~4, and the mixture was extracted by shaking at room temperature. After standing, the phases were separated to obtain the molybdenum-loaded organic phase and the raffinate. Back-extraction: The molybdenum-loaded organic phase is mixed with 7-9 mol / L ammonia water at a ratio of O / A = 1-4:1, and after extraction by shaking at room temperature, the phases are separated by standing. The back-extraction liquid and the extracted organic phase are obtained after separation. Evaporation crystallization: Mix the back-extraction solution with the alkaline leaching solution, heat to evaporate the solvent, and when the ammonium molybdate reaches supersaturation and crystallization begins, stop heating, continue stirring to allow the crystals to precipitate, filter, wash, and dry to obtain ammonium molybdate crystals; Calcination decomposition: The ammonium molybdate crystals are heated to 540~560℃ and calcined for 1.5~2.5h to obtain the target molybdenum trioxide.

[0005] The technical solution described in this invention has the following advantages compared with the prior art: (1) After the oxygen pressure acid leaching process, the molybdenum in the molybdenum concentrate is converted from molybdenum sulfide to molybdenum oxide. When leached with ammonia water, the molybdenum enters the solution in the form of easily soluble ammonium molybdate, avoiding the problem of sodium sulfate crystal formation and system blockage when leaching with sodium hydroxide.

[0006] (2) After leaching with ammonia, ammonium molybdate solution can be obtained directly, which simplifies the extraction process and can greatly reduce the amount of solution in the subsequent extraction process.

[0007] (3) The molybdenum in the acid leaching solution enters the back-extraction liquid through the extraction-back-extraction process. Using ammonia water as the back-extraction reagent, an ammonium molybdate solution can be obtained. This solution has the same composition as the alkaline leaching solution. It can be directly mixed and then subjected to evaporation, crystallization and calcination treatment to prepare molybdenum trioxide with a purity greater than 98%.

[0008] (4) This technical solution only requires the extraction of a small amount of residual molybdenum in the acid leaching solution, which greatly reduces the processing capacity of the extraction system, thereby reducing the consumption of organic solvents and equipment investment. Direct ammonia leaching of acid leaching residue produces an ammonium molybdate solution that does not require purification, and the process steps are simple.

[0009] (5) Ammonia leaching can be carried out at room temperature or medium temperature, which reduces energy consumption. There is no SO2 emission during the ammonia leaching process. Ammonia water can be used as both a leaching agent and a back-extraction agent. The reagent system is unified, which reduces the types of materials and management costs.

[0010] In summary, the technical solution described in this invention simplifies the process flow, reduces energy consumption and reagent costs, effectively improves the recovery rate and purity of molybdenum, enhances the environmental friendliness of the process, and provides a new, efficient, and clean solution for the separation and recovery of molybdenum resources. Attached Figure Description

[0011] Figure 1 This is a process flow diagram of the technical solution described in this invention. Detailed Implementation

[0012] The present invention will be further described below, but this is not intended to limit the invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the scope of protection of the present invention.

[0013] The alkaline leaching and synergistic extraction recovery process for molybdenum in molybdenum concentrate described in this invention includes the following steps: Oxygen-pressure acid leaching: Molybdenum concentrate is mixed with 45-55 g / L sulfuric acid at a solid-liquid ratio of 1:3-7 to form a slurry. Under closed conditions, the mixture is stirred and heated to 180-250℃. When the temperature reaches the set value, the oxygen partial pressure is adjusted to 0.5-1.5 MPa. After reacting for 1.5-2.5 hours, the mixture is cooled. The leached material is then filtered and washed to obtain acid leaching solution and acid leaching residue. Alkali leaching: The acid leaching residue is mixed with 3-6 mol / L ammonia water at a solid-liquid ratio of 1:2-5, the temperature is adjusted to 25-80℃, and the mixture is stirred for 0.5-1.5 hours. The leached material is then filtered and washed to obtain alkaline leaching solution and alkaline leaching residue. Extraction: The acid leaching solution and the extractant were mixed at a ratio of O / A = 1:1~4, and the mixture was extracted by shaking at room temperature. After standing, the phases were separated to obtain the molybdenum-loaded organic phase and the raffinate. Back-extraction: The molybdenum-loaded organic phase is mixed with 7-9 mol / L ammonia water at a ratio of O / A = 1-4:1, and after extraction by shaking at room temperature, the phases are separated by standing. The back-extraction liquid and the extracted organic phase are obtained after separation. Evaporation crystallization: Mix the back-extraction solution with the alkaline leaching solution, heat to evaporate the solvent, and when the ammonium molybdate reaches supersaturation and crystallization begins, stop heating, continue stirring to allow the crystals to precipitate, filter, wash, and dry to obtain ammonium molybdate crystals; Calcination decomposition: The ammonium molybdate crystals are heated to 540~560℃ and calcined for 1.5~2.5h to obtain the target molybdenum trioxide.

[0014] The concentration of the sulfuric acid is preferably 50 g / L.

[0015] The preferred temperature for the oxygen pressure acid leaching is 222~228℃.

[0016] The oxygen partial pressure is preferably 1.2 MPa.

[0017] The preferred reaction time for the oxygen pressure acid leaching is 2 hours.

[0018] The preferred solid-liquid ratio of the acid leaching residue to ammonia water is 1:4.

[0019] In the alkaline leaching step, the concentration of the ammonia water is preferably 5 mol / L.

[0020] The preferred temperature for alkali leaching is 40°C.

[0021] The preferred reaction time for the alkaline leaching is 1 hour.

[0022] The extractant is MN-316 composite extractant with a concentration of 40%.

[0023] The extraction temperature is 25~30℃ and the time is 5~20min.

[0024] In the back-extraction step, the concentration of the ammonia water is preferably 8 mol / L.

[0025] The back-extraction temperature is 25~30℃, and the time is 5~20min.

[0026] The extracted organic phase (i.e., the extractant) can be regenerated and returned to the extraction step for continued use.

[0027] In the evaporation and crystallization step, after the back-extraction liquid is mixed with the alkaline leaching liquid, the pH of the mixed system is adjusted to 6 using ammonia water.

[0028] In the evaporation and crystallization step, the heating temperature is preferably 70~75℃.

[0029] In the evaporation crystallization step, the solvent is heated to evaporate, and the ammonium molybdate reaches supersaturation. At the start of crystallization, the final specific gravity of the solution is 1.40 g / L.

[0030] In the evaporation and crystallization step, the stirring speed is preferably 135~140 rpm.

[0031] The drying process is vacuum drying, and the preferred temperature is 70°C.

[0032] The preferred calcination time is 2 hours.

[0033] Example 1

[0034] Oxygen-pressure acid leaching: Molybdenum concentrate and 50 g / L sulfuric acid are mixed into a slurry at a solid-liquid ratio of 1:5 and then placed in a titanium-lined pressure vessel. Under sealed conditions, the mixture is stirred and heated to 225°C. When the temperature reaches the set value, the oxygen partial pressure is adjusted to 1.2 MPa. After reacting for 2 hours, the mixture is cooled, the vessel is removed, and the leaching material is filtered and washed to obtain acid leaching solution and acid leaching residue.

[0035] Alkali leaching: The acid leaching residue is mixed with 5 mol / L ammonia water at a solid-liquid ratio of 1:4. The mixture is then placed in a heat-collecting constant temperature stirrer, the temperature is adjusted to 40℃, and the mixture is stirred for 1 hour. The leached material is then filtered and washed to obtain alkaline leaching solution and alkaline leaching residue.

[0036] Extraction: The acid leaching solution and 40% MN-316 composite extractant were mixed in a separatory funnel at a ratio of O / A=1:2. The separatory funnel was placed in a water bath constant temperature shaker and extracted by shaking at 25℃ for 5 min. After standing, the phases were separated to obtain the molybdenum-loaded organic phase and the raffinate.

[0037] Back-extraction: The molybdenum-loaded organic phase was mixed with 8 mol / L ammonia water at a ratio of O / A = 2:1, placed in a water bath constant temperature shaker, and extracted by shaking at 25℃ for 5 min. After standing, the phases were separated to obtain the back-extracted liquid and the extracted organic phase.

[0038] Evaporation and Crystallization: The back-extraction solution is mixed with the alkaline leaching solution and poured into a beaker. The pH of the mixture is adjusted to 6 using ammonia. The beaker is placed on an electric furnace lined with an asbestos mesh and heated to 70°C to allow the solvent to gradually evaporate, gradually increasing the concentration of ammonium molybdate until supersaturation is achieved, with a final specific gravity of 1.40 g / L. When crystallization begins, heating is stopped, and stirring is continued at 135 rpm to allow the crystals to precipitate. The precipitate is then filtered, washed, and the wet ammonium molybdate is obtained. This wet material is then vacuum-dried at 70°C to obtain ammonium molybdate crystals.

[0039] Calcination and decomposition: Ammonium molybdate crystals were placed in a muffle furnace, heated to 550℃, and calcined for 2 hours to obtain the target molybdenum trioxide. Monitoring showed that the molybdenum conversion rate reached 99.2% and the molybdenum leaching rate reached 99.04%.

[0040] Elemental analysis of ammonium molybdate and molybdenum trioxide in this process was performed, and the results are shown in the table below.

[0041] Table 1. Major elemental analysis of ammonium molybdate and molybdenum trioxide (mass fraction %)

[0042] Example 2

[0043] Oxygen-pressure acid leaching: Molybdenum concentrate and 45 g / L sulfuric acid are mixed into a slurry at a solid-liquid ratio of 1:7 and then placed in a titanium-lined pressure vessel. Under sealed conditions, the mixture is stirred and heated to 250°C. When the temperature reaches the set value, the oxygen partial pressure is adjusted to 1.5 MPa. After reacting for 1.5 hours, the mixture is cooled, the vessel is removed, and the leaching material is filtered and washed to obtain acid leaching solution and acid leaching residue.

[0044] Alkali leaching: The acid leaching residue is mixed with 3 mol / L ammonia water at a solid-liquid ratio of 1:5, and then placed in a heat-collecting constant temperature stirrer. The temperature is adjusted to 25℃, and the reaction is stirred for 1.5 hours. The leaching material is then filtered and washed to obtain alkaline leaching solution and alkaline leaching residue.

[0045] Extraction: The acid leaching solution and 40% MN-316 composite extractant were mixed in a separatory funnel at a ratio of O / A=1:1. The separatory funnel was placed in a water bath constant temperature shaker and extracted by shaking at 30℃ for 20 min. After standing, the phases were separated to obtain the molybdenum-loaded organic phase and the raffinate.

[0046] Back-extraction: The molybdenum-loaded organic phase was mixed with 7 mol / L ammonia water at a ratio of O / A = 1:1, placed in a water bath constant temperature shaker, and extracted by shaking at 30℃ for 20 min. After standing, the phases were separated to obtain the back-extracted liquid and the extracted organic phase.

[0047] Evaporation and Crystallization: The back-extraction solution is mixed with the alkaline leaching solution and poured into a beaker. The pH of the mixture is adjusted to 6 using ammonia. The beaker is placed on an electric furnace lined with an asbestos mesh and heated to 75°C to allow the solvent to gradually evaporate, gradually increasing the concentration of ammonium molybdate until supersaturation is achieved, with a final specific gravity of 1.40 g / L. When crystallization begins, heating is stopped, and stirring is continued at 140 rpm to allow the crystals to precipitate. The precipitate is then filtered, washed, and the wet ammonium molybdate is obtained. This wet material is then vacuum-dried at 70°C to obtain ammonium molybdate crystals.

[0048] Calcination and decomposition: Ammonium molybdate crystals were placed in a muffle furnace, heated to 540℃, and calcined for 2.5 h to obtain the target molybdenum trioxide.

[0049] Example 3

[0050] Oxygen-pressure acid leaching: Molybdenum concentrate and 55 g / L sulfuric acid are mixed into a slurry at a solid-liquid ratio of 1:3 and then placed in a titanium-lined pressure vessel. Under sealed conditions, the mixture is stirred and heated to 180°C. When the temperature reaches the set value, the oxygen partial pressure is adjusted to 0.5 MPa. After reacting for 2.5 hours, the mixture is cooled, the vessel is removed, and the leaching material is filtered and washed to obtain acid leaching solution and acid leaching residue.

[0051] Alkali leaching: The acid leaching residue is mixed with 6 mol / L ammonia water at a solid-liquid ratio of 1:2 and then placed in a heat-collecting constant temperature stirrer. The temperature is adjusted to 80℃ and the reaction is stirred for 0.5 h. The leaching material is then filtered and washed to obtain alkaline leaching solution and alkaline leaching residue.

[0052] Extraction: The acid leaching solution and 40% MN-316 composite extractant were mixed in a separatory funnel at a ratio of O / A=1:4. The separatory funnel was placed in a water bath constant temperature shaker and extracted by shaking at 25℃ for 10 min. After standing, the phases were separated to obtain the molybdenum-loaded organic phase and the raffinate.

[0053] Back-extraction: The molybdenum-loaded organic phase was mixed with 9 mol / L ammonia water at a ratio of O / A = 4:1, placed in a water bath constant temperature shaker, and extracted by shaking at 25℃ for 10 min. After standing, the phases were separated to obtain the back-extracted liquid and the extracted organic phase.

[0054] Evaporation and Crystallization: The back-extraction solution is mixed with the alkaline leaching solution and poured into a beaker. The pH of the mixture is adjusted to 6 using ammonia. The beaker is placed on an electric furnace lined with an asbestos mesh and heated to 70°C to allow the solvent to gradually evaporate, gradually increasing the concentration of ammonium molybdate until supersaturation is achieved, with a final specific gravity of 1.40 g / L. When crystallization begins, heating is stopped, and stirring is continued at 135 rpm to allow the crystals to precipitate. The precipitate is then filtered, washed, and the wet ammonium molybdate is obtained. This wet material is then vacuum-dried at 70°C to obtain ammonium molybdate crystals.

[0055] Calcination and decomposition: Ammonium molybdate crystals were placed in a muffle furnace, heated to 560℃, and calcined for 1.5 h to obtain the target molybdenum trioxide.

Claims

1. A process for the alkaline leaching and co-extraction recovery of molybdenum from molybdenum concentrate, characterized in that, Includes the following steps: Oxygen-pressure acid leaching: Molybdenum concentrate is mixed with 45-55 g / L sulfuric acid at a solid-liquid ratio of 1:3-7 to form a slurry. Under closed conditions, the mixture is stirred and heated to 180-250℃. When the temperature reaches the set value, the oxygen partial pressure is adjusted to 0.5-1.5 MPa. After reacting for 1.5-2.5 hours, the mixture is cooled. The leached material is then filtered and washed to obtain acid leaching solution and acid leaching residue. Alkali leaching: The acid leaching residue is mixed with 3-6 mol / L ammonia water at a solid-liquid ratio of 1:2-5, the temperature is adjusted to 25-80℃, and the mixture is stirred for 0.5-1.5 hours. The leached material is then filtered and washed to obtain alkaline leaching solution and alkaline leaching residue. Extraction: The acid leaching solution and the extractant were mixed at a ratio of O / A = 1:1~4, and the mixture was extracted by shaking at room temperature. After standing, the phases were separated to obtain the molybdenum-loaded organic phase and the raffinate. Back-extraction: The molybdenum-loaded organic phase is mixed with 7-9 mol / L ammonia water at a ratio of O / A = 1-4:1, and after extraction by shaking at room temperature, the phases are separated by standing. The back-extraction liquid and the extracted organic phase are obtained after separation. Evaporation crystallization: Mix the back-extraction solution with the alkaline leaching solution, heat to evaporate the solvent, and when the ammonium molybdate reaches supersaturation and crystallization begins, stop heating, continue stirring to allow the crystals to precipitate, filter, wash, and dry to obtain ammonium molybdate crystals; Calcination decomposition: The ammonium molybdate crystals are heated to 540~560℃ and calcined for 1.5~2.5h to obtain the target molybdenum trioxide.

2. The alkaline leaching and co-extraction recovery process for molybdenum from molybdenum concentrate according to claim 1, characterized in that, The temperature of the oxygen pressure acid leaching is 222~228℃.

3. The alkaline leaching and co-extraction recovery process for molybdenum in molybdenum concentrate according to claim 1, characterized in that, The oxygen partial pressure is 1.2 MPa.

4. The alkaline leaching and co-extraction recovery process for molybdenum in molybdenum concentrate according to claim 1, characterized in that, The reaction time for the oxygen pressure acid leaching is 2 hours.

5. The alkaline leaching and co-extraction recovery process for molybdenum in molybdenum concentrate according to claim 1, characterized in that, The solid-liquid ratio of the acid leaching residue to ammonia water is 1:

4.

6. The alkaline leaching and co-extraction recovery process for molybdenum from molybdenum concentrate according to any one of claims 1 or 5, characterized in that, In the alkaline leaching step, the concentration of the ammonia water is 5 mol / L.

7. The alkaline leaching and co-extraction recovery process for molybdenum from molybdenum concentrate according to claim 1, characterized in that, The alkaline leaching temperature is 40°C.

8. The alkaline leaching and co-extraction recovery process for molybdenum from molybdenum concentrate according to claim 1, characterized in that, The alkaline leaching reaction time is 1 hour.

9. The alkaline leaching and co-extraction recovery process for molybdenum in molybdenum concentrate according to claim 1, characterized in that, In the back-extraction step, the concentration of the ammonia water is 8 mol / L.

10. The alkaline leaching and co-extraction recovery process for molybdenum in molybdenum concentrate according to claim 1, characterized in that, The calcination time is 2 hours.

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