A method for efficient processing and recovery of copper and molybdenum from high-copper-molybdenum concentrate

Abstract

This invention discloses a method for the efficient treatment and recovery of copper and molybdenum from high-copper-molybdenum concentrate. The method involves pre-treating low-grade high-copper-molybdenum concentrate with oxygen-pressure water leaching to remove copper. The resulting low-copper-molybdenum concentrate is then processed through oxidative roasting, alkaline leaching, extraction, and evaporation crystallization to prepare ammonium molybdate. The copper-removing solution is then subjected to synergistic extraction and stepwise back-extraction to recover copper and molybdenum. This method not only achieves efficient removal of copper from the high-copper-molybdenum concentrate, avoiding the impact of copper on molybdenum recovery and ammonium molybdate preparation, but also innovatively employs a synergistic extraction and stepwise back-extraction method to separately enrich and recover copper and molybdenum. Matching this with an electrowinning process achieves high-value copper recovery. Simultaneously, the acidic copper extraction residue and the alkaline molybdenum extraction residue are synergistically neutralized, saving reagent costs.

Description

Technical Field

[0001] This invention relates to the field of molybdenum smelting technology, specifically to a method for the efficient processing and recovery of copper and molybdenum from high-copper-molybdenum concentrate. Background Technology

[0002] Molybdenum is a strategic rare metal widely used in steel, chemical, electronics, aerospace, biomedicine, agriculture, and national defense industries due to its excellent thermal and electrical conductivity, high-temperature resistance, wear resistance, and corrosion resistance. Molybdenum resources are mainly divided into two categories: copper-molybdenum associated resources and molybdenite independent deposits. With increasing molybdenum production and consumption, the grade of molybdenum for development and utilization is decreasing, and the mineral complexity is increasing. Therefore, the development and utilization of low-grade, complex associated molybdenum deposits has become a hot topic.

[0003] In the recovery of molybdenum from copper-molybdenum associated resources, efficient and precise separation of copper and molybdenum is difficult, resulting in high levels of mutual inclusion in the separated products. While molybdenum in copper concentrate is mainly enriched in the slag during pyrometallurgical processes, having little impact on the smelting process and product purity, excessive copper content in molybdenum concentrate severely affects the quality of subsequent products such as ferromolybdenum or ammonium molybdate. On one hand, increased copper content affects the desulfurization conversion efficiency of molybdenum concentrate. Under oxidative roasting conditions, copper oxidation makes the material sticky, causing agglomeration and affecting the oxidation effect. On the other hand, copper introduced from the raw materials remains in the molybdenum oxide roasted slag, impacting product quality in ferromolybdenum smelting or molybdenum chemical preparation processes, requiring a dedicated copper removal section and resulting in molybdenum loss. Based on these impacts, the industry typically sets requirements for copper content in molybdenum concentrate, requiring Cu ≤ 0.5%. As the copper content increases, the selling price gradually decreases. However, due to limitations in resource endowment and mining and beneficiation process requirements, low-grade high-copper-molybdenum concentrate will be the mainstream raw material in the current molybdenum smelting industry. Therefore, research on copper-molybdenum separation and extraction technologies for high-copper, low-grade molybdenum concentrate is becoming increasingly urgent.

[0004] Research on copper-molybdenum separation and extraction technologies for high-copper, low-grade molybdenum concentrates mainly includes roasting-acid leaching, electrochemical leaching, bioleaching, and pressure leaching. Among these, roasting-acid leaching is more easily matched with the ferromolybdenum smelting industry, producing suitable low-copper ferromolybdenum smelting raw materials, and is therefore the most widely used in China. However, the presence of copper in the molybdenum concentrate affects the roasting oxidation effect, thus impacting molybdenum recovery and product purity. Electrochemical leaching and bioleaching both aim to leach molybdenum into a solution and are more suitable for the molybdenum chemical preparation industry. However, due to limitations in the application and market of molybdenum chemicals, industrial-scale application is rare, and there is a certain investment risk. Alkaline hot-press leaching uses NaOH and Na2CO3 as leaching media, allowing molybdenum to enter the liquid phase as soluble molybdates, while copper remains in the solid phase as a poorly soluble component, achieving copper-molybdenum separation. However, under operating conditions, the consumption of leaching agent is high, resulting in high production costs. Acidic hot-press oxygen leaching can preferentially leach copper based on the different oxidation sequences of various sulfide minerals. However, the endpoint pH of acidic leaching is relatively low, resulting in significant molybdenum leaching losses. Oxygen-press water leaching can achieve endpoint pH control by optimizing leaching conditions, thereby allowing molybdenum to remain in the slag and separate from copper as much as possible. However, detailed process schemes and control methods are rarely reported. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide a method for the efficient processing and recovery of copper and molybdenum from high-copper-molybdenum concentrate.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for efficiently processing and recovering copper and molybdenum from high-copper-molybdenum concentrate includes the following steps:

[0008] S1, Oxygen-Pressure Water Leaching: The high-copper-molybdenum concentrate is mixed with water and slurried, then placed in a high-pressure reactor for oxidative leaching. The pH is adjusted by alkaline solution during the leaching process. After leaching, the slag and liquid are cooled and filtered to obtain copper-removed slag and copper-removed liquid. The copper-removed slag is a low-copper-molybdenum concentrate. The copper-removed slag is transferred to step S2 for processing, and the copper-removed liquid is transferred to step S6 for processing.

[0009] S2, Oxidative roasting: The copper-removing slag obtained in step S1 is subjected to oxidative roasting to obtain oxidized roasted sand;

[0010] S3. Alkali leaching of calcined sand: The oxidized calcined sand obtained in step S2 is mixed with NaOH solution for alkali leaching, and oxidizing agent and leaching aid are added. After alkali leaching is completed, the mixture is filtered and washed to obtain alkali leaching solution and alkali leaching residue.

[0011] S4. Extraction-back-extraction: The alkaline leaching solution obtained in step S3 is mixed with the organic phase A for countercurrent extraction. The resulting organic phase is washed countercurrently with water. The washed organic phase is then back-extracted countercurrently with ammonia water as the back-extraction solution to finally obtain ammonium molybdate solution, alkaline raffinate, and lean organic phase.

[0012] S5. Evaporation and crystallization: The ammonium molybdate solution obtained in step S4 is evaporated and concentrated, and then cooled and crystallized to obtain the ammonium molybdate product. The concentration of ammonia in the crystallization mother liquor is adjusted and returned to step S4 for use as a back-extraction solution.

[0013] S6. Copper-molybdenum co-extraction: The copper-removed solution obtained in step S1 is mixed with the extracting organic phase B and subjected to countercurrent extraction to obtain a loaded organic phase and an acidic raffinate.

[0014] S7. Copper-molybdenum stepwise back-extraction: After washing the loaded organic phase obtained in step S6 with water, copper back-extraction is first performed using sulfuric acid solution as copper back-extraction solution, and then molybdenum back-extraction is performed using ammonia water as molybdenum back-extraction solution to obtain copper sulfate solution and ammonium molybdate solution respectively. The lean organic phase obtained after back-extraction is returned to step S6 to continue to participate in copper-molybdenum synergistic extraction.

[0015] S8. Copper Electrowinning: The copper sulfate solution obtained in step S7 is electrowinning to obtain cathode copper product and electrowinning lean solution. The electrowinning lean solution is returned to the copper back-extraction in step S6 as copper back-extraction solution.

[0016] Further, in step S1, during the oxygen-pressure water leaching, the liquid-to-solid ratio of high-copper-molybdenum concentrate to water is 3-6:1 (mL / g), the leaching temperature is 150-170℃, the oxygen partial pressure is 0.3-0.8MPa, the leaching time is 0.5-3h, and the final pH of the copper removal solution is 1.2-1.8.

[0017] Furthermore, in step S2, the temperature of the oxidative calcination is 500-700℃.

[0018] Further, in step S3, the liquid-to-solid ratio of oxidized calcined sand to NaOH solution is 2-6:1 (mL / g), the concentration of NaOH solution is 80-150 g / L, the alkali leaching temperature is 80-95℃, and the alkali leaching time is 0.5-3 h; the oxidant is air, oxygen, or hydrogen peroxide, and the leaching aid is sodium carbonate, sodium phosphate, or a mixture of the two.

[0019] Further, in step S4, the extracted organic phase A includes an extractant, a modifier, and an organic diluent, wherein the extractant is N263 or N235, the modifier is 2-octanol or 2-decyl alcohol organic phase, and the organic diluent is kerosene, and the volume concentrations of the extractant, modifier, and organic diluent are 10%-40%, 20%, and 40%-70%, respectively.

[0020] Further, in step S4, the oil-to-water ratio of the alkaline leaching solution to the extracted organic phase A is 8-10:1, and the number of countercurrent extraction stages is 5-8; the oil-to-water ratio of the organic phase obtained by countercurrent extraction to the water is 1-3:1, and the number of countercurrent washing stages is 1-3; the concentration of NH3 in the back-extraction solution is 5-8 mol / L, the oil-to-water ratio of the washed organic phase to the ammonia water is 6-10:1, and the number of countercurrent back-extraction stages is 3-10.

[0021] Furthermore, in step S5, the evaporation and concentration temperature is 95-100℃.

[0022] Further, in step S6, the extractable organic phase B includes an aldoxime copper extractant and a diluent kerosene, wherein the volume concentration of the aldoxime copper extractant in the extractable organic phase is 10%-30%; the ratio of the copper removal solution to the oil-water mixture in the extractable organic phase B is 0.5-3:1, and the countercurrent extraction stage is 1-5 stages.

[0023] Further, in step S7, the sulfuric acid concentration in the copper back-extraction solution is 150-300 g / L, the oil-to-water ratio of the copper back-extraction is 0.5-2:1, and the number of stages is 1-3; the ammonia concentration in the molybdenum back-extraction solution is 0.5-3 mol / L, the oil-to-water ratio of the molybdenum back-extraction is 1-10:1, and the number of stages is 1-3.

[0024] Furthermore, part of the alkaline raffinate obtained in step S4 is returned to step S1 for pH adjustment and / or returned to step S3 for NaOH solution preparation. The remaining part is combined with the acidic raffinate obtained in step S6 for neutralization treatment to remove iron and desalt. The recycled water obtained after iron removal and desalting is returned to step S1 for mineral pulping or returned to step S3 for NaOH solution preparation. The organic-lean phase obtained in step S4 is washed with pure water and returned for extraction in step S4.

[0025] The beneficial effects of this invention are as follows:

[0026] 1) In the method of this invention, copper is removed from low-grade high-copper-molybdenum concentrate by oxygen-pressure water leaching pretreatment. The resulting low-copper-molybdenum concentrate is then processed into ammonium molybdate by oxidative roasting-alkali leaching-extraction-evaporation crystallization. Copper and molybdenum are recovered from the copper removal liquid by synergistic extraction-stepwise back-extraction. This not only achieves efficient removal of copper from high-copper-molybdenum concentrate and avoids the influence of copper on molybdenum recovery and ammonium molybdate preparation, but also innovatively uses a copper-molybdenum synergistic extraction-stepwise back-extraction method to enrich and recover copper and molybdenum separately. The electrowinning process is matched to achieve high-value copper recovery. At the same time, the acidic copper extraction residue and the alkaline molybdenum extraction residue are synergistically neutralized to save reagent costs.

[0027] 2) Unlike the existing process for preparing ammonium molybdate from molybdenum concentrate smelting, this invention places the copper removal process before oxidative roasting, eliminating the adverse effects of copper oxidation causing material to become sticky and agglomerate, thus affecting the desulfurization conversion effect. This increases the desulfurization oxidation rate from 98.5% to over 99.9%, directly improving the direct recovery rate of the molybdenum process.

[0028] 3) The method of the present invention can avoid the problems of large reagent consumption and difficult treatment of mixed nitrate nitrogen and ammonia nitrogen wastewater caused by acid leaching to remove impurities and ammonia leaching to extract molybdenum in the classic ammonia leaching process, as well as the problem of large water volume caused by dilution and pH adjustment in the traditional alkaline leaching-ion exchange process.

[0029] 4) This invention is based on the specific properties of high-copper-molybdenum concentrate. It utilizes the oxidation sequence of pyrite, chalcopyrite, and molybdenite under pressure (pyrite > chalcopyrite > pyrite) to precisely control oxygen pressure leaching conditions, preferentially leaching pyrite and chalcopyrite, maximizing copper leaching into the solution, while molybdenum remains mostly in the unoxidized MoS2 form, subsequently reacting with Cu during extraction. 2+ They are extracted together into the organic phase, but during the back-extraction of copper with sulfuric acid, the structure cannot be effectively coordinated and therefore remains on the organic phase. When back-extracted with ammonia, ammonium molybdate is formed and desorbed from the organic phase.

[0030] 6) In this invention, the main components of the acidic raffinate produced by copper-molybdenum co-extraction are H2SO4 and Fe2(SO4)3, and the main components of the alkaline raffinate produced by extraction-back-extraction are NaOH, Na2SiO3, Al(OH)3, etc. Part of the alkaline raffinate can be returned to the oxygen pressure leaching section to adjust the reaction pH, part can be returned to the alkaline leaching solution preparation, and the rest can be combined with the acidic raffinate for neutralization and desalination, saving reagent costs.

[0031] 7) This invention can effectively process molybdenum concentrates with different copper contents. By taking into account both beneficiation and smelting, the requirements for copper content in molybdenum concentrate products in the beneficiation stage can be appropriately relaxed to further improve molybdenum recovery rate and increase the economic benefits of enterprises.

[0032] 8) In the method of the present invention, a portion of the alkaline raffinate (product of the process of preparing ammonium molybdate from low copper-molybdenum concentrate) is reused to control the pH at the end of oxygen pressure leaching. This allows a very small portion of the oxidized molybdenum to remain in the slag in the form of molybdic acid, reducing losses. At the same time, it ensures that iron remains in the slag in the form of iron-vanadium as much as possible, avoiding the subsequent impact on copper extraction. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0035] Example 1

[0036] This embodiment uses a high-copper-molybdenum concentrate from Heilongjiang Province as raw material, and its main components are shown in Table 1.

[0037] Table 1 Composition of a high-copper-molybdenum concentrate from Heilongjiang Province

[0038]

[0039] like Figure 1As shown, the method for efficient processing and recovery of copper and molybdenum from high-copper-molybdenum concentrate in this embodiment includes the following steps:

[0040] Oxygen-pressure water leaching: High-copper-molybdenum concentrate was mixed with water at a liquid-to-solid ratio of 3:1 (mL / g) and slurried. The mixture was then placed in a high-pressure reactor and reacted at 170℃ and an oxygen partial pressure of 0.8 MPa for 0.5 h. The copper removal slag rate was 85.8%, and the pH of the copper removal liquor was 1.30. The copper content in the copper removal slag decreased to 0.05%, while the molybdenum content increased to 45.38%. The copper concentration in the copper removal liquor was 4.38 g / L, and the molybdenum concentration was 0.76 g / L.

[0041] Oxidative roasting: The copper-removed slag was oxidatively roasted at 650℃ to obtain oxidized roasted sand with a yield of 86%. The molybdenum content of the roasted sand was increased to 52.7%, and the copper content was 0.06%.

[0042] Alkali leaching of calcined ore: Calcined ore was mixed with 150 g / L NaOH solution at a liquid-to-solid ratio of 4:1 (mL / g). Hydrogen peroxide was added slowly at a rate of 10 g / L, and sodium carbonate was added as a leaching aid at a rate of 50 g / L. The reaction was carried out at 80°C for 3 hours. The alkali leaching residue rate was 26.5%, the molybdenum content in the residue decreased to 4.10%, and the copper content was 0.23%. The alkali leaching solution contained 105.3 g / L of molybdenum and less than 0.02 mg / L of copper.

[0043] Extraction-back-extraction: In the organic phase A, the extractant is N263 converted from carbonate, the modifier is 2-octanol, and the diluent is kerosene. The volume concentrations of the extractant, modifier, and diluent in the organic phase A are 10%, 20%, and 70%, respectively. The alkaline leaching solution and the organic phase are subjected to 8-stage countercurrent extraction at an oil-water ratio of 8:1. The resulting alkaline raffinate contains 63 mg / L of molybdenum. The resulting organic phase is washed with water at an oil-water ratio of 3:1 for 1 stage of countercurrent washing, and then back-extracted with 8 mol / L ammonia water at an oil-water ratio of 10:1 for 10 stages of countercurrent extraction to obtain an ammonium molybdate solution and a lean organic phase. The lean organic phase is washed with pure water and returned for extraction-back-extraction.

[0044] Evaporation and crystallization: After deoiling, the ammonium molybdate solution is evaporated and concentrated at 95°C, and then cooled and crystallized to obtain the ammonium molybdate product; the mother liquor is returned to the extraction-back-extraction process after adjusting the ammonia concentration as the back-extraction solution.

[0045] The copper-molybdenum co-extraction was performed on the copper-removed solution obtained from oxygen-pressure water leaching using an extractive organic phase B. The extractive organic phase B included an aldoxime copper extractant and a diluent, kerosene. The volume concentration of the aldoxime copper extractant was 30%, the oil-to-water ratio was 2:1, and the extraction stage was 1. The resulting organic phase and acidic raffinate contained 15.85 mg / L of copper and 0.5 mg / L of molybdenum.

[0046] Stepwise copper-molybdenum back-extraction: After washing the supported organic phase with water, copper back-extraction is first performed using sulfuric acid solution as the copper back-extraction solution. The sulfuric acid concentration is 300 g / L, the oil-to-water ratio is 2:1, and the back-extraction stage is 3 stages. Then, molybdenum back-extraction is performed using ammonia water as the molybdenum back-extraction solution. The ammonia water concentration is 3 mol / L, the oil-to-water ratio is 1:1, and the back-extraction stage is 3 stages. The copper and molybdenum back-extraction rates can both reach over 99%. The obtained copper sulfate solution is electrowinning to recover copper, and the obtained ammonium molybdate solution is returned to the alkaline leaching process to recover ammonium molybdate. The lean organic phase obtained after the stepwise copper-molybdenum back-extraction is returned to the copper-molybdenum co-extraction process, and the lean solution from the electrowinning process is returned to the copper back-extraction process for use as the copper back-extraction solution.

[0047] The alkaline raffinate is partially returned to the oxygen-pressure water leaching process for pH adjustment and / or returned to the calcined ...

[0048] Example 2

[0049] This embodiment uses a high-copper-molybdenum concentrate from the Tibet Autonomous Region as raw material, and its main components are shown in Table 2.

[0050] Table 2 Composition of a high-copper-molybdenum concentrate in Tibet Autonomous Region

[0051]

[0052] like Figure 1 As shown, the method for efficient processing and recovery of copper and molybdenum from high-copper-molybdenum concentrate in this embodiment includes the following steps:

[0053] Oxygen-pressure water leaching: High-copper-molybdenum concentrate was mixed with water at a liquid-to-solid ratio of 6:1 (mL / g) and slurried. The mixture was then placed in a high-pressure reactor and reacted at 150℃ and an oxygen partial pressure of 0.3 MPa for 3 hours. The slag yield of the copper-removing slag was 88.6%, and the pH of the copper-removing liquor was 1.78. The copper content in the copper-removing slag could be reduced to 0.31%, and the molybdenum content could be increased to 50.69%. The copper concentration in the copper-removing liquor was 3.85 g / L, and the molybdenum concentration was 35.8 mg / L.

[0054] Oxidative roasting: The copper-removed slag was oxidized and roasted at 600℃ to obtain oxidized roasted sand with a yield of 88%. The molybdenum content of the roasted sand was increased to 57.60%, and the copper content was 0.35%.

[0055] Alkali leaching of calcined ore: Calcined ore was mixed with 80 g / L NaOH solution at a liquid-to-solid ratio of 6:1 (mL / g). Hydrogen peroxide was added slowly at a rate of 10 g / L, and sodium carbonate was added as a leaching aid at a rate of 50 g / L. The reaction was carried out at 85°C for 2 hours. The leaching residue yield was 27.0%, the molybdenum content in the residue decreased to 5.02%, and the copper content was 1.30%. The leaching solution contained 113.6 g / L of molybdenum and less than 0.02 mg / L of copper.

[0056] Extraction-back-extraction: In the organic phase A, the extractant is saponified N235, the modifier is 2-octanol, and the diluent is kerosene. The volume concentrations of the extractant, modifier, and diluent in the organic phase A are 30%, 20%, and 50%, respectively. The alkaline leaching solution and the organic phase A are subjected to five stages of countercurrent extraction at an oil-water ratio of 10:1. The resulting alkaline raffinate contains 55 mg / L of molybdenum. The resulting organic phase is washed with water at an oil-water ratio of 3:1 using a single stage of countercurrent washing, followed by ten stages of countercurrent back-extraction with 8 mol / L ammonia water at an oil-water ratio of 6:1. This yields an ammonium molybdate solution and a lean organic phase. The lean organic phase is washed with pure water and returned for extraction-back-extraction.

[0057] Evaporation and crystallization: After deoiling, the ammonium molybdate solution is evaporated and concentrated at 100°C, and then cooled and crystallized to obtain the ammonium molybdate product; the mother liquor is used as a back-extraction solution after adjusting the ammonia concentration.

[0058] The copper-molybdenum co-extraction was performed on the copper-removed solution obtained from oxygen-pressure water leaching using an extractive organic phase B. The extractive organic phase B contained an aldoxime copper extractant and a diluent, kerosene. The volume concentration of the aldoxime copper extractant was 10%, the oil-to-water ratio was 3:1, and the extraction stage was 3 stages. The resulting organic phase and acidic raffinate contained 33.8 mg / L of copper and 0.2 mg / L of molybdenum.

[0059] Stepwise copper-molybdenum back-extraction: After washing the supported organic phase with water, copper back-extraction is first performed using sulfuric acid solution as the copper back-extraction solution. The sulfuric acid concentration is 150 g / L, the oil-to-water ratio is 0.5:1, and the back-extraction stage is 1. Then, molybdenum back-extraction is performed using ammonia solution as the molybdenum back-extraction solution. The ammonia concentration is 0.5 mol / L, the oil-to-water ratio is 10:1, and the back-extraction stage is 1. Both copper and molybdenum back-extraction rates can reach over 99%. The obtained copper sulfate solution is electrowinning to recover copper. The ammonium molybdate solution is returned to the alkaline leaching process to recover ammonium molybdate. The lean organic phase is returned to the extraction organic phase used for copper-molybdenum co-extraction. The electrowinning lean solution is returned to the copper back-extraction process as the copper back-extraction solution.

[0060] The alkaline raffinate is partially returned to the oxygen-pressure water leaching process for pH adjustment and / or returned to the calcined ...

[0061] Example 3

[0062] This embodiment uses a high-copper-molybdenum concentrate from Heilongjiang Province as raw material, and its main components are shown in Table 3.

[0063] Table 3 Composition of a high-copper-molybdenum concentrate from Heilongjiang Province

[0064] Element Cu (%) Mo (%) Fe (%) Re(g / t) S(％) content 3.99 45.29 4.47 324.7 34.6

[0065] Analysis shows that the molybdenum concentrate has a high Cu and Fe content. Process mineralogy studies have also revealed that the proportion of pyrite and chalcopyrite in the minerals is higher than that in Examples 1 and 2. Therefore, this ore sample was selected for comparative verification tests.

[0066] Oxygen-pressure water leaching: Two portions of molybdenum concentrate of equal mass were simultaneously mixed with water at a liquid-to-solid ratio of 5:1 (mL / g) and slurried. The mixtures were then placed in a high-pressure reactor and reacted at 160℃ and an oxygen partial pressure of 0.8 MPa for 0.5 h. One group was left uncontrolled at pH (final pH = 0.93), while the other group had alkali added to control the pH at 1.28. The experimental results are shown in Table 4.

[0067] Table 4 Results of oxygen pressure water leaching test for high copper-molybdenum concentrate

[0068]

[0069] The results above show that controlling the pH during oxygen-pressure water leaching can significantly reduce the molybdenum content in the solution, effectively reducing molybdenum loss.

[0070] Copper-molybdenum synergistic extraction of copper-removing solution: The copper-removing solution was extracted using an aldoxime-based copper extractant and kerosene. The extractant volume concentration was 30%, the oil-to-water ratio was 3:1, and the extraction stage was 3 stages. Extraction experiments were conducted on the copper-removing solutions obtained from the two groups of oxygen-pressure water leaching, and the results are shown in Table 5.

[0071] Table 5. Results of copper-molybdenum synergistic extraction experiments in copper-removing solutions.

[0072]

[0073] The results show that the extraction rate of molybdenum in the solution obtained by controlling the pH is significantly higher than that without pH control. The main reason is that under the condition of pH=1.28, the solubility of molybdic acid is low, and at this time, most of the molybdenum in the copper removal solution is in the form of MoO2. 2+ The complexed form exists, and subsequently reacts with Cu during extraction. 2+ Both were extracted into the organic phase; however, at pH = 0.93, the solubility of molybdic acid increased, and MoO4... 2- MoO2 could not be fully formed 2+ The morphology, therefore, cannot be changed during extraction with Cu. 2+They enter the organic phase together.

[0074] The comparative verification in Example 3 shows that the present invention is applicable to copper removal from molybdenum concentrate containing different proportions of pyrite and chalcopyrite. Controlling the appropriate pH during the oxygen pressure leaching stage can significantly reduce the leaching loss of molybdenum, and copper extractant can be used to synergistically extract and recover molybdenum from the leachate, thus achieving efficient molybdenum recovery.

[0075] For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all such changes and modifications should be included within the protection scope of the claims of this invention.

Claims

1. A method for efficiently processing and recovering copper and molybdenum from high-copper-molybdenum concentrate, characterized in that, Includes the following steps: S1, Oxygen-Pressure Water Leaching: The high-copper-molybdenum concentrate is mixed with water and slurried, then placed in a high-pressure reactor for oxidative leaching. The pH is adjusted by alkaline solution during the leaching process. After leaching, the slag and liquid are cooled and filtered to obtain copper-removed slag and copper-removed liquid. The copper-removed slag is a low-copper-molybdenum concentrate. The copper-removed slag is transferred to step S2 for processing, and the copper-removed liquid is transferred to step S6 for processing. S2, Oxidative roasting: The copper-removing slag obtained in step S1 is subjected to oxidative roasting to obtain oxidized roasted sand; S3, Alkali leaching of calcined sand: The oxidized calcined sand obtained in step S2 is mixed with NaOH solution for alkali leaching, and oxidizing agent and leaching aid are added. After alkali leaching is completed, the mixture is filtered and washed to obtain alkali leaching solution and alkali leaching residue. S4. Extraction-back-extraction: The alkaline leaching solution obtained in step S3 is mixed with the organic phase A for countercurrent extraction. The resulting organic phase is washed countercurrently with water. The washed organic phase is then back-extracted countercurrently with ammonia water as the back-extraction solution to finally obtain ammonium molybdate solution, alkaline raffinate, and lean organic phase. S5. Evaporation and crystallization: The ammonium molybdate solution obtained in step S4 is evaporated and concentrated, and then cooled and crystallized to obtain the ammonium molybdate product. The concentration of ammonia in the crystallization mother liquor is adjusted and returned to step S4 for use as a back-extraction solution. S6. Copper-molybdenum co-extraction: The copper-removed solution obtained in step S1 is mixed with the extracting organic phase B and subjected to countercurrent extraction to obtain a loaded organic phase and an acidic raffinate. S7. Copper-molybdenum stepwise back-extraction: After washing the loaded organic phase obtained in step S6 with water, copper back-extraction is first performed using sulfuric acid solution as copper back-extraction solution, and then molybdenum back-extraction is performed using ammonia water as molybdenum back-extraction solution to obtain copper sulfate solution and ammonium molybdate solution respectively. The lean organic phase obtained after back-extraction is returned to step S6 to continue to participate in copper-molybdenum synergistic extraction. S8. Copper Electrowinning: The copper sulfate solution obtained in step S7 is electrowinning to obtain cathode copper product and electrowinning lean solution. The electrowinning lean solution is returned to the copper back-extraction in step S7 as copper back-extraction solution. In step S1, during the oxygen-pressure water leaching, the liquid-to-solid ratio of high-copper-molybdenum concentrate to water is 3-6:1 (mL / g), the leaching temperature is 150-170℃, the oxygen partial pressure is 0.3-0.8MPa, the leaching time is 0.5-3h, and the final pH of the copper removal solution is 1.2-1.

8. In step S3, the liquid-to-solid ratio of oxidized calcined sand to NaOH solution is 2-6:1 (mL / g), the concentration of NaOH solution is 80-150 g / L, the alkali leaching temperature is 80-95℃, and the alkali leaching time is 0.5-3 h; the oxidant is air, oxygen, or hydrogen peroxide, and the leaching aid is sodium carbonate, sodium phosphate, or a mixture of the two. In step S4, the extracted organic phase A includes an extractant, a modifier, and an organic diluent, wherein the extractant is N263 or N235, the modifier is 2-octanol or 2-decyl alcohol organic phase, and the organic diluent is kerosene, and the volume concentrations of the extractant, modifier, and organic diluent are 10%-40%, 20%, and 40%-70%, respectively; In step S6, the extractable organic phase B includes an aldoxime copper extractant and a diluent kerosene. The volume concentration of the aldoxime copper extractant in the extractable organic phase is 10%-30%. The ratio of the copper removal solution to the oil-water content of the extractable organic phase B is 0.5-3:1, and the countercurrent extraction stage is 1-5 stages.

2. The method for efficient processing and recovery of copper and molybdenum from high-copper-molybdenum concentrate according to claim 1, characterized in that, In step S2, the oxidative calcination temperature is 500-700℃.

3. The method for efficient processing and recovery of copper and molybdenum from high-copper-molybdenum concentrate according to claim 1, characterized in that, In step S4, the oil-to-water ratio of the alkaline leaching solution to the extracted organic phase A is 8-10:1, and the number of countercurrent extraction stages is 5-8; the oil-to-water ratio of the organic phase obtained by countercurrent extraction to the water is 1-3:1, and the number of countercurrent washing stages is 1-3; the concentration of NH3 in the back-extraction solution is 5-8 mol / L, the oil-to-water ratio of the washed organic phase to the ammonia water is 6-10:1, and the number of countercurrent back-extraction stages is 3-10.

4. The method for efficient processing and recovery of copper and molybdenum from high-copper-molybdenum concentrate according to claim 1, characterized in that, In step S5, the evaporation and concentration temperature is 95-100℃.

5. The method for efficient processing and recovery of copper and molybdenum from high-copper-molybdenum concentrate according to claim 1, characterized in that, In step S7, the sulfuric acid concentration in the copper back-extraction solution is 150-300 g / L, the oil-to-water ratio of the copper back-extraction is 0.5-2:1, and the number of stages is 1-3; the ammonia concentration in the molybdenum back-extraction solution is 0.5-3 mol / L, the oil-to-water ratio of the molybdenum back-extraction is 1-10:1, and the number of stages is 1-3.

6. The method for efficient processing and recovery of copper and molybdenum from high-copper-molybdenum concentrate according to claim 1, characterized in that, The alkaline raffinate obtained in step S4 is partially returned to step S1 for pH adjustment and / or returned to step S3 for NaOH solution preparation. The remaining portion is combined with the acidic raffinate obtained in step S6 for neutralization treatment to remove iron and desalt. The recycled water obtained after iron removal and desalting is returned to step S1 for mineral pulping or returned to step S3 for NaOH solution preparation. The organic-lean phase obtained in step S4 is washed with pure water and returned for extraction in step S4.

Images