A method for extracting tungsten and molybdenum from low-grade tungsten-molybdenum ore

Abstract

The present application relates to a kind of methods for extracting tungsten and molybdenum from low-grade tungsten-molybdenum ore, belonging to the technical field of non-ferrous metallurgy, which solves the problems of harsh conditions, low extraction efficiency, high cost and environmental pollution in the prior art for extracting tungsten and molybdenum from low-grade tungsten-molybdenum ore.The method comprises: using sulfuric acid to leach low-grade tungsten-molybdenum ore, and obtaining leach liquor and leach residue by solid-liquid separation; using a cationic extractant to extract molybdenum from the leach liquor, to obtain a tungsten-containing molybdenum extraction raffinate and a negative molybdenum organic phase; using a neutral extractant to extract tungsten from the tungsten-containing molybdenum extraction raffinate, to obtain a tungsten extraction raffinate and a negative tungsten organic phase.The present application method is carried out at normal temperature and pressure, and cleverly utilizes the complexing characteristics of molybdenum to tungsten in low-grade tungsten-molybdenum mixed ore under acidic conditions, to achieve the synergistic leaching of tungsten and molybdenum, with high tungsten and molybdenum extraction efficiency, simple operation, no need to add complexing agents such as phosphoric acid, and significantly reduced leaching cost; and it is clean and environmentally friendly, promoting the development and utilization of low-grade tungsten-molybdenum ore.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology for non-ferrous metals, and more particularly to a method for extracting tungsten and molybdenum from low-grade tungsten-molybdenum ore. Background Technology

[0002] Tungsten and molybdenum are strategic rare metals in China, possessing properties such as high melting point, high density, and high-temperature strength. They are widely used in various fields including civilian, industrial, and military applications, and are known as the "teeth of industry." Due to scarce global reserves and strong demand, tungsten and molybdenum have long been included in the strategic reserve lists of many countries, and their strategic position is irreplaceable. The consumption of tungsten and molybdenum is mainly concentrated in steel smelting, cemented carbide, and aerospace, and with the advancement of technology and the development of emerging industries, the demand for tungsten, molybdenum, and their alloys will continue to grow. With the rapid depletion of high-grade tungsten and molybdenum resources, the raw materials that my country can process for tungsten and molybdenum smelting have also undergone profound changes, with low-grade tungsten and molybdenum ores gradually becoming an important supplement to tungsten and molybdenum smelting.

[0003] Existing processes use sodium carbonate pressure leaching to treat low-grade tungsten-molybdenum ore. This method requires high temperature and pressure conditions above 200℃, producing a large amount of hazardous waste alkaline leaching residue, posing significant environmental problems. Furthermore, separating large quantities of tungsten and molybdenum under alkaline conditions is extremely difficult, typically requiring sulfidation, which incurs high reagent costs. The sulfur-phosphorus mixed acid method for co-leaching scheelite, invented by Central South University, not only processes tungsten ore but also achieves efficient recovery of associated metals, although it requires the addition of a large amount of phosphoric acid.

[0004] Therefore, there is an urgent need for a new method to extract tungsten and molybdenum from low-grade tungsten-molybdenum ores, which can make the extraction process simple, efficient, clean, environmentally friendly, and low-cost, so as to achieve both efficient utilization of low-grade tungsten-molybdenum ores and meet the requirements of low-carbon and environmental protection. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a method for extracting tungsten and molybdenum from low-grade tungsten-molybdenum ore, in order to solve at least one of the problems of harsh conditions, low extraction efficiency, high cost and environmental pollution in the prior art when extracting tungsten and molybdenum from low-grade tungsten-molybdenum ore.

[0006] On one hand, embodiments of the present invention provide a method for extracting tungsten and molybdenum from low-grade tungsten-molybdenum ore, the method comprising:

[0007] (1) Low-grade tungsten-molybdenum ore was leached with sulfuric acid, and the leaching solution and leaching residue were obtained by solid-liquid separation;

[0008] (2) Molybdenum is extracted from the leachate using a cationic extractant to obtain a molybdenum-containing residual liquid containing tungsten and a negative molybdenum organic phase; molybdenum is back-extracted from the negative molybdenum organic phase using a back-extractant to obtain a molybdenum-containing back-extractant;

[0009] (3) Tungsten is extracted from the tungsten-containing molybdenum extraction residue using a neutral extractant to obtain a tungsten extraction residue and a negative tungsten organic phase; tungsten is back-extracted from the negative tungsten organic phase using a back-extractant to obtain a tungsten-containing back-extractant.

[0010] Furthermore, the percentage content of (Mo+WO3) in the low-grade tungsten-molybdenum ore is 5%-30%.

[0011] Furthermore, the mass percentage of Mo / WO3 in the low-grade tungsten-molybdenum ore is greater than 2 / 3.

[0012] Furthermore, the low-grade tungsten-molybdenum ore comprises calcium molybdate, calcium tungstate, calcium fluoride, calcium carbonate, and magnesium carbonate.

[0013] Furthermore, in step (1), the leaching liquid-to-solid ratio is 10L / kg-30L / kg.

[0014] Furthermore, in step (1), the leaching temperature is 80-100℃ and the time is 2-6h.

[0015] Furthermore, in step (1), the mass concentration of (Mo+WO3) in the leachate is not higher than 30 g / L, and the sulfuric acid concentration is 20-50 g / L.

[0016] Furthermore, in step (2), the cationic extractant is one or more of P204, P507 and Cyanex272, and the diluent is kerosene, wherein the volume concentration of the cationic extractant solution is 20%-40%.

[0017] Furthermore, in step (3), the neutral extractant is TBP (tributyl phosphate), and the diluent is kerosene, wherein the volume concentration of the neutral extractant solution is 20%-40%.

[0018] Furthermore, the method also includes recycling the organic phase obtained after back-extraction back to the extraction step.

[0019] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0020] 1. The method of this invention uses only sulfuric acid as the leaching agent. Under normal temperature and pressure conditions, it utilizes the complexation properties of molybdenum and tungsten to generate a series of soluble tungsten-molybdenum isopolyacid molecules (such as Mo3W4O). 24 6- MoW6O 24 6-This method promotes the dissolution of tungsten and achieves synergistic leaching of tungsten and molybdenum. It is simple to operate and has a high extraction efficiency (up to 98%). Compared with the sulfuric acid mixed acid method, molybdenum is more likely to form cations without phosphoric acid as a complexing agent, resulting in more thorough separation of tungsten and molybdenum and reducing costs. In addition, during the leaching and extraction of tungsten and molybdenum from low-grade tungsten and molybdenum ores using sulfuric acid, only gypsum slag is generated. Compared with existing technologies, no alkali boiling slag or phosphorus slag is generated, making the new process cleaner and more environmentally friendly.

[0021] 2. In order to obtain a higher tungsten-molybdenum leaching rate, the present invention controls the percentage content of (Mo+WO3) in the low-grade tungsten-molybdenum ore within the range of 5%-30%; at the same time, it is necessary to control the mass percentage of Mo / WO3 in the low-grade tungsten-molybdenum ore to be greater than 2 / 3. If necessary, the Mo / WO3 ratio in the low-grade tungsten-molybdenum ore can be achieved by adding calcium molybdate ore.

[0022] 3. The method of the present invention controls the mass concentration of (Mo+WO3) in the leachate of the low-grade tungsten-molybdenum ore to be no higher than 30 g / L and the sulfuric acid concentration to be 30-50 g / L, so as to prevent tungsten from forming tungstic acid precipitate, which is conducive to improving the leaching rate and facilitating the extraction and separation of molybdenum.

[0023] 4. In this invention, cationic extractant and neutral extractant are used sequentially to extract the leachate to achieve complete separation of tungsten and molybdenum. After subsequent processing, relatively pure molybdic acid and ammonium tungstate products are obtained respectively.

[0024] 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

[0025] 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.

[0026] Figure 1 This is a process flow diagram of the present invention for extracting tungsten and molybdenum from low-grade tungsten-molybdenum ore;

[0027] Figure 2 The chemical reaction equation for the formation of a tungsten-molybdenum complex by the complexation of molybdenum and tungsten under acidic conditions. Detailed Implementation

[0028] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention 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.

[0029] With the advancement of science and technology and the development of emerging industries, the demand for tungsten, molybdenum and their alloys, known as the "teeth of industry," continues to grow. As high-grade tungsten and molybdenum resources are rapidly depleted, the raw materials that my country's tungsten and molybdenum smelting can process have also undergone profound changes, with low-grade tungsten and molybdenum ores gradually becoming an important supplement to tungsten and molybdenum smelting.

[0030] For example, the Yechangping tungsten-molybdenum mine in Lushi County, Henan Province, is located in the Qinling-Dabie Mountains molybdenum-tungsten metallogenic belt in western Henan. It is a large molybdenum deposit, also containing tungsten, iron, and other associated minerals. The Yechangping molybdenum mine is a typical example of a highly oxidized molybdenum-tungsten associated deposit. The high-oxidation ore has complex properties, with fine-grained, micro-disseminated molybdenum-tungsten minerals, some exhibiting isomorphous inclusions that are difficult to liberate. Furthermore, it contains high levels of gangue minerals with high mud content, such as calcium magnesium carbonates, clay, and gypsum, making it extremely difficult to beneficiate. To ensure tungsten and molybdenum recovery rates, only low-grade tungsten-molybdenum ore can be produced. In addition, the Sandaozhuang mine in Luanchuan County also produces a large quantity of low-grade tungsten-molybdenum ore.

[0031] However, currently only the sodium carbonate pressure leaching method and the sulfur-phosphorus mixed acid method can achieve efficient leaching of low-grade tungsten-molybdenum ores. However, the sodium carbonate pressure leaching method has very demanding application conditions, generally carried out in a high-pressure autoclave at 200℃. It consumes a large amount of sodium carbonate and produces a large amount of hazardous waste leaching residue, posing significant environmental problems. Furthermore, the separation of large quantities of tungsten and molybdenum under alkaline conditions is very difficult, and sulfidation is generally used, resulting in high reagent costs. The sulfur-phosphorus mixed acid method uses phosphoric acid as a complexing agent, requiring the addition of a large amount of phosphoric acid during the leaching process. For low-grade tungsten-molybdenum ores, the phosphoric acid consumption increases significantly, leading to high costs.

[0032] Therefore, this invention provides a method for extracting tungsten and molybdenum from low-grade tungsten-molybdenum ore, the specific process flow of which is as follows: Figure 1 As shown, the method includes:

[0033] (1) Low-grade tungsten-molybdenum ore was leached with sulfuric acid, and the leaching solution and leaching residue were obtained by solid-liquid separation;

[0034] (2) Molybdenum is extracted from the leachate using a cationic extractant to obtain a molybdenum-containing residual liquid containing tungsten and a negative molybdenum organic phase; molybdenum is back-extracted from the negative molybdenum organic phase using a back-extractant to obtain a molybdenum-containing back-extractant;

[0035] (3) Tungsten is extracted from the tungsten-containing molybdenum extraction residue using a neutral extractant to obtain a tungsten extraction residue and a negative tungsten organic phase; tungsten is back-extracted from the negative tungsten organic phase using a back-extractant to obtain a tungsten-containing back-extractant.

[0036] Specifically, in order to improve the leaching rate of tungsten and molybdenum, in step (1), the percentage content of (Mo+WO3) in the low-grade tungsten and molybdenum ore is 5%-30%. If the content is too high, it will cause tungstic acid precipitation to coat the minerals and hinder leaching; if the content is too low, it will cause the concentration of tungsten and molybdenum in the leachate to be too low, affecting economic efficiency. The percentage content of (Mo+WO3) in the low-grade tungsten and molybdenum ore of the present invention can be 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, and any value between two adjacent values.

[0037] Specifically, in order to fully utilize the complexing effect of molybdenum, in step (1), the mass percentage of Mo / WO3 in the low-grade tungsten-molybdenum ore is greater than 2 / 3. If the mass percentage of Mo / WO3 is too small, it will lead to insufficient complexing ability of molybdenum on tungsten, affecting the leaching rate of tungsten. The mass percentage of Mo / WO3 in the low-grade tungsten-molybdenum ore of the present invention can be 6 / 8, 1 / 1, 15 / 13, 6 / 5, 2 / 1, 3, 4 and any other numerical ratio greater than 2 / 3.

[0038] Furthermore, in order to achieve efficient leaching of low-grade tungsten-molybdenum ore in step (1), for low-grade tungsten-molybdenum ore with a Mo / WO3 mass percentage of less than or equal to 2 / 3, calcium molybdate ore can be added to increase the Mo / WO3 mass percentage.

[0039] Specifically, in step (1), the low-grade tungsten-molybdenum ore contains multiple mineral phases such as calcium molybdate, calcium tungstate, calcium fluoride, calcium carbonate, and magnesium carbonate.

[0040] Specifically, in step (1), during the leaching process of the low-grade tungsten-molybdenum ore, molybdenum will complex with tungsten, promoting the leaching of tungsten. Partial complexation reactions are shown in [the diagram]. Figure 2 The chemical reaction formula is shown.

[0041] Specifically, from Figure 2 It can be seen that in step (1), the leachate contains HMo8O 26 3- MoO2 2+ MoW6O 24 6- Mo2W5O 24 6- Mo3W4O 24 6- Mo4W3O 24 6- Mo5W2O 24 6- Mo6WO 24 6- H2MoW 11 O42 10- One or more complexes in the form of [the compound].

[0042] Specifically, in step (1), the device used for leaching the low-grade tungsten-molybdenum ore is an atmospheric pressure leaching device.

[0043] Specifically, in step (1), sulfuric acid can be replaced by hydrochloric acid or nitric acid.

[0044] Specifically, in step (1), the initial concentration of added sulfuric acid is appropriately adjusted within the range of 80-200 g / L according to the content and proportion of (Mo+WO3) in the low-grade tungsten-molybdenum ore to be leached. Specifically, it can be 80 g / L, 88.2 g / L, 90 g / L, 98.1 g / L, 100 g / L, 110 g / L, 117.6 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, 170 g / L, 180 g / L, 190 g / L, 200 g / L, and any value between two adjacent values.

[0045] Specifically, in step (1), the amount of sulfuric acid added before leaching is such that the concentration of sulfuric acid after the leaching reaction of the low-grade tungsten-molybdenum ore is 20-50 g / L. If the concentration is too high, it will cause the precipitation of tungstic acid; if the concentration is too low, it will be detrimental to the extraction and separation of molybdenum. Specifically, the concentration can be 20 g / L, 22 g / L, 24 g / L, 26 g / L, 28 g / L, 30 g / L, 32 g / L, 34 g / L, 36 g / L, 38 g / L, 40 g / L, 42 g / L, 44 g / L, 46 g / L, 48 g / L, 40 g / L, or any value between two adjacent values.

[0046] Specifically, in step (1), the leaching liquid-to-solid ratio is 10L / kg-30L / kg, the leaching temperature is 80-100℃, and the leaching time is 2-6h. The leaching liquid-to-solid ratio described in this invention can specifically be 10L / kg, 11L / kg, 12L / kg, 14L / kg, 15L / kg, 16L / kg, 18L / kg, 20L / kg, 22L / kg, 24L / kg, 26L / kg, 28L / kg, 30L / kg, or any value between any two adjacent values; the leaching temperature described in this invention can specifically be 80℃, 85℃, 90℃, 95℃, 100℃, or any value between any two adjacent values; the leaching time described in this invention can specifically be 2h, 3h, 4h, 5h, 6h, or any value between any two adjacent values.

[0047] Specifically, in step (1), the solid-liquid separation can be filtration and washing to obtain leachate and leachate residue.

[0048] Specifically, to ensure a high tungsten-molybdenum leaching rate, in step (1), the mass concentration of (Mo+WO3) in the leachate is no higher than 30 g / L, and the sulfuric acid concentration is 20-50 g / L. If the mass concentration of (Mo+WO3) in the leachate is too high, it will cause tungstic acid precipitation, affecting the tungsten-molybdenum leaching rate; if it is too low, it will reduce the amount of minerals processed and increase smelting costs. If the concentration of sulfuric acid in the leachate is too high, it will cause tungstic acid precipitation; if it is too low, it will affect the extraction and separation effect of molybdenum. The specific mass concentration of (Mo+WO3) in the leachate of the present invention can be 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, 20 g / L, 21 g / L, 22 g / L, 23 g / L, 24 g / L, 25 g / L, 26 g / L, 27 g / L, 28 g / L, 29 g / L, 30 g / L, or any concentration between two adjacent values.

[0049] It should be noted that this invention controls the percentage content of (Mo+WO3) in low-grade tungsten-molybdenum ore, the ratio of the two, and the concentration of sulfuric acid added as a leaching agent. It utilizes the complexation properties of molybdenum and tungsten under acidic conditions to generate a series of soluble tungsten-molybdenum isopolyacid molecules, which promote the dissolution of tungsten and achieve synergistic leaching of tungsten and molybdenum. The operation is simple and the extraction efficiency is high (up to 98%).

[0050] It should be noted that, compared with the sulfur-phosphorus mixed acid method in the prior art, in the absence of phosphoric acid as a complexing agent, molybdenum exists mostly in the form of isopolyacids or tungsten-molybdenum heteropolyacids, which are more easily converted into molybdenum acyl cations than the phosphomolybdenum heteropolyacids formed when phosphorus is present (phosphomolybdenum heteropolyacids require higher acidity to dissociate into molybdenum acyl cations and phosphoric acid). The separation of tungsten and molybdenum is more thorough and the cost is reduced. In addition, in the process of leaching and extracting tungsten and molybdenum from low-grade tungsten-molybdenum ore with sulfuric acid, only water is generated. Compared with the prior art, no alkali boiling residue or phosphorus residue is generated, and the new process is cleaner and more environmentally friendly.

[0051] It should be noted that the present invention can use a cationic extractant to extract molybdenum from a leachate containing the aforementioned series of soluble tungsten-molybdenum isopolyacids / heteropolyacids. This is because, at a certain acidity, some molybdenum exists in the form of molybdenum acyl cations, and the cationic extractant has the ability to selectively extract molybdenum acyl cations. As this portion of molybdenum acyl cations is extracted and separated, the molybdenum isopolyacids or molybdenum heteropolyacids in the solution will continue to transform into molybdenum acyl cations. Tungsten, however, does not form cations and remains in the form of anions, which can be extracted by neutral extractants.

[0052] Specifically, in step (2), the cationic extractant is one or more of P204, P507 and Cyanex272, and the diluent is kerosene. The volume concentration of the cationic extractant solution is 20%-40%, preferably 20%-30%, and can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, or 40%, with the remainder being diluent.

[0053] Specifically, in step (2), the stripping agent is hydrogen peroxide with a mass concentration of 15%.

[0054] Specifically, in step (2), both extraction and back extraction are countercurrent extractions, and the number of extraction stages is 4-10, which can be 4, 5, 6, 7, 8, 9, or 10 stages.

[0055] Specifically, in order to improve the extraction efficiency of molybdenum and make it easier for molybdenum to transfer from the aqueous phase to the organic phase, in step (2), the oil-water ratio of the present invention is controlled to be 1 / 1 to 1 / 3, which can be 1 / 1, 1 / 2, or 1 / 3. Too high or too low oil-water ratios during the extraction process may lead to poor extraction results. Although a high oil-water ratio is beneficial for the extraction of molybdenum, it will reduce the back-extraction efficiency, increase costs and the difficulty of subsequent processing. Too low oil-water ratios may lead to insufficient contact between the extractant and the aqueous phase, affecting the transfer efficiency of the target compound.

[0056] Furthermore, in step (2), the oil-water ratio of the back-extraction is controlled to be 10 / 1 to 20 / 1, which can be 10 / 1, 11 / 1, 12 / 1, 13 / 1, 14 / 1, 15 / 1, 16 / 1, 17 / 1, 18 / 1, 19 / 1, or 20 / 1.

[0057] Specifically, in step (2) above, the molybdenum-containing back-extraction solution can be evaporated and crystallized to obtain molybdic acid, which can then be calcined to obtain molybdenum trioxide.

[0058] It should be noted that the present invention can use a neutral extractant to extract tungsten from the tungsten-containing molybdenum extraction residue obtained in step (2).

[0059] Specifically, in step (3), the neutral extractant is tributyl phosphate (TBP), and the diluent is kerosene. The volume concentration of the neutral extractant solution is 20%-40%, preferably 25%-35%, and can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, or 40%, with the remainder being diluent.

[0060] Specifically, in step (3), the stripping agent is ammonia water with a concentration of 4-6 mol / L, and the concentration can be 4 mol / L, 5 mol / L, or 6 mol / L.

[0061] Specifically, in step (3), both extraction and back extraction are countercurrent extractions, and the number of extraction stages is 4-10, which can be 4, 5, 6, 7, 8, 9, or 10 stages.

[0062] Specifically, in order to improve the extraction efficiency of tungsten, in step (3), the present invention controls the oil-water ratio of the extraction to be 1 / 1 to 1 / 5, which can be 1 / 1, 1 / 2, 1 / 3, 1 / 4, or 1 / 5.

[0063] Furthermore, in step (3), the oil-water ratio of the back-extraction is controlled to be 5 / 1 to 20 / 1, which can be 5 / 1, 6 / 1, 7 / 1, 8 / 1, 9 / 1, 10 / 1, 11 / 1, 12 / 1, 13 / 1, 14 / 1, 15 / 1, 16 / 1, 17 / 1, 18 / 1, 19 / 1, or 20 / 1.

[0064] Specifically, in step (3) above, the tungsten-containing back-extraction solution can be evaporated and crystallized to obtain tungstic acid, and then calcined to obtain tungsten trioxide product.

[0065] It should be noted that, in order to improve the system's water utilization efficiency and reduce reagent consumption, after step (3), the remaining liquid after tungsten extraction is partially returned to step (1) for recycling, and partially opened into the wastewater treatment system.

[0066] It should be noted that, in order to improve the extraction efficiency of molybdenum and tungsten, save costs, and reduce actual environmental pollution, the organic solvents after back-extraction in steps (2) and (3) can be returned to the extraction step for recycling.

[0067] Specifically, the overall yield of molybdenum in the method of this invention is over 97%, and the overall yield of tungsten is over 97%.

[0068] The technical solution of the present invention will be further explained and illustrated below through specific embodiments.

[0069] Example 1

[0070] (1) Using low-grade tungsten-molybdenum ore as raw material, which contains various mineral phases such as calcium molybdate, calcium tungstate, calcium fluoride, calcium carbonate, and magnesium carbonate, the raw ore contains about 8% WO3 and about 6% Mo. Leaching is carried out with sulfuric acid, and the leachate and leaching residue are obtained by filtration and washing.

[0071] The initial concentration of sulfuric acid added to the low-grade tungsten-molybdenum ore was 117.6 g / L, the leaching liquid-to-solid ratio was 10 L / kg, the leaching temperature was 90℃, the leaching time was 3 h, and after leaching and filtration, the mass concentration of (Mo+WO3) in the leaching solution was measured to be 13.75 g / L, and the sulfuric acid concentration was 50 g / L; the leaching rates of tungsten and molybdenum were greater than 98%.

[0072] (2) Molybdenum is selectively extracted from the leachate obtained in step (1) using a cationic extractant to obtain a tungsten-containing molybdenum extraction residue and a negative molybdenum organic phase;

[0073] The cationic extractant was P204 with a concentration of 40%, the diluent was kerosene, the oil-water ratio was O / A = 1 / 2, countercurrent extraction was used, the number of extraction stages was 10, the extraction rate of molybdenum reached 95%, and the co-extraction rate of tungsten was 0.5%.

[0074] Molybdenum was back-extracted from the negative molybdenum organic phase using 15% hydrogen peroxide as the back-extraction agent. The back-extraction ratio was O / A = 10 / 1, and the number of back-extraction stages was 5. A back-extraction solution with a Mo content of 110 g / L was obtained, which was then evaporated and decomposed to obtain molybdic acid product.

[0075] The organic relative leachate after back-extraction is recycled for selective extraction of molybdenum.

[0076] (3) Tungsten was extracted from the molybdenum extraction residue containing tungsten using a neutral extractant to obtain the tungsten extraction residue and the negative tungsten organic phase;

[0077] The neutral extractant was TBP with a concentration of 20%, the diluent was kerosene, the oil-water ratio was O / A = 1 / 3, countercurrent extraction was used, the number of extraction stages was 10, and the extraction rates of tungsten and residual molybdenum both reached over 99%.

[0078] Tungsten was back-extracted from the negative tungsten organic phase using 5 mol / L ammonia water as the back-extraction agent. The back-extraction ratio was O / A = 8 / 1, and the number of back-extraction stages was 5. The back-extraction solution containing 190 g / L WO3 and 7.2 g / L Mo was obtained. After deep removal of molybdenum by traditional selective precipitation, the product was obtained by evaporation and crystallization.

[0079] The organic phase after back-extraction is recycled to extract tungsten from the tungsten-containing molybdenum extraction residue;

[0080] (4) Part of the tungsten extraction residue from step (3) is returned to step (1) for recycling, and part of it is opened into the wastewater treatment system.

[0081] Example 2

[0082] (1) Using low-grade tungsten-molybdenum ore as raw material, containing multiple mineral phases such as calcium molybdate, calcium tungstate, calcium fluoride, calcium carbonate, and magnesium carbonate, among which WO3 is about 8% and Mo is about 6%. Leaching is carried out with sulfuric acid, and the leachate and leaching residue are obtained by filtration and washing.

[0083] The initial concentration of sulfuric acid added to the low-grade tungsten-molybdenum ore was 98.1 g / L, the leaching liquid-to-solid ratio was 15 L / kg, the leaching temperature was 95℃, the leaching time was 4 h, and after leaching and filtration, the mass concentration of (Mo+WO3) in the leaching liquid was measured to be 9.2 g / L, the sulfuric acid concentration was 48 g / L, and the leaching rates of tungsten and molybdenum were both above 99%.

[0084] (2) Molybdenum is selectively extracted from the leachate obtained in step (1) using a cationic extractant to obtain a tungsten-containing molybdenum extraction residue and a negative molybdenum organic phase;

[0085] The cationic extractant was P204 with a concentration of 40%, the diluent was kerosene, the oil-water ratio was O / A = 1 / 2, countercurrent extraction was used, the number of extraction stages was 10, the extraction rate of molybdenum reached 93%, and the co-extraction of tungsten was less than 0.5%.

[0086] Molybdenum was back-extracted from the negative molybdenum organic phase using 15% hydrogen peroxide as the back-extraction agent. The back-extraction ratio was O / A = 15 / 1, and the number of back-extraction stages was 5. A back-extraction solution with a Mo content of 110 g / L was obtained, which was then evaporated and decomposed to obtain molybdic acid product.

[0087] The organic relative leachate after back-extraction is recycled for selective extraction of molybdenum.

[0088] (3) Tungsten was extracted from the molybdenum extraction residue containing tungsten using a neutral extractant to obtain the tungsten extraction residue and the negative tungsten organic phase;

[0089] The neutral extractant was tributyl phosphate with a concentration of 20%, the diluent was kerosene, the oil-water ratio was O / A = 1 / 4, countercurrent extraction was used, the number of extraction stages was 5, and the extraction rate of tungsten and residual molybdenum reached 98%.

[0090] Tungsten was back-extracted from the negative tungsten organic phase using 4 mol / L ammonia water as the back-extraction agent. The back-extraction ratio was O / A = 10 / 1, and the number of back-extraction stages was 5. The back-extraction solution with WO3 content of 200 g / L and Mo content of 10 g / L was obtained. After molybdenum was removed by selective precipitation, the product was obtained by evaporation and crystallization.

[0091] The organic phase after back-extraction is recycled to extract tungsten from the tungsten-containing molybdenum extraction residue;

[0092] (4) Part of the tungsten extraction residue from step (3) is returned to step (1) for recycling, and part of it is opened into the wastewater treatment system.

[0093] Example 3

[0094] (1) Low-grade tungsten-molybdenum ore was used as raw material. The raw ore contained about 12% WO3 and about 10% Mo. Sulfuric acid was used for leaching, and the leachate and leaching residue were obtained by filtration and washing.

[0095] The initial concentration of sulfuric acid added to the low-grade tungsten-molybdenum ore was 88.2 g / L, the leaching solution-to-solid ratio was 12 L / kg, the leaching temperature was 95℃, the leaching time was 6 h, and after leaching and filtration, the mass concentration of (Mo+WO3) in the leaching solution was measured to be 18.33 g / L, and the sulfuric acid concentration was 30 g / L; the leaching rate of tungsten and molybdenum was approximately 98.5%.

[0096] (2) Molybdenum is selectively extracted from the leachate obtained in step (1) using a cationic extractant to obtain a tungsten-containing molybdenum extraction residue and a negative molybdenum organic phase;

[0097] The cationic extractant was P507 with a concentration of 30%, the diluent was kerosene, the oil-water ratio was O / A = 2 / 3, countercurrent extraction was used, the number of extraction stages was 8, the extraction rate of molybdenum reached 96%, and the co-extraction rate of tungsten was 0.3%.

[0098] Molybdenum was back-extracted from the negative molybdenum organic phase using 15% hydrogen peroxide as the back-extraction agent. The back-extraction ratio was O / A = 10 / 1, and the number of back-extraction stages was 4. A back-extraction solution with a Mo content of 115 g / L was obtained, which was then evaporated and decomposed to obtain molybdic acid product.

[0099] The organic relative leachate after back-extraction is recycled for selective extraction of molybdenum.

[0100] (3) Tungsten was extracted from the molybdenum extraction residue containing tungsten using a neutral extractant to obtain the tungsten extraction residue and the negative tungsten organic phase;

[0101] The neutral extractant was TBP with a concentration of 30%, the diluent was kerosene, the oil-water ratio was O / A = 2 / 3, countercurrent extraction was used, the number of extraction stages was 10, and the extraction rates of tungsten and residual molybdenum both reached over 99%.

[0102] Using 5 mol / L ammonia water as the stripping agent, tungsten was stripped from the negative tungsten organic phase. The stripping ratio was O / A = 15 / 1, and the number of stripping stages was 5. The stripping solution with WO3 content of 150 g / L and Mo content of 7.5 g / L was obtained. After deep removal of molybdenum by traditional selective precipitation method, ammonium paratungstate product was obtained by evaporation and crystallization.

[0103] The organic phase after back-extraction is recycled to extract tungsten from the tungsten-containing molybdenum extraction residue;

[0104] (4) Part of the tungsten extraction residue from step (3) is returned to step (1) for recycling, and part of it is opened into the wastewater treatment system.

[0105] Example 4

[0106] (1) Low-grade tungsten-molybdenum ore was used as raw material. The raw ore contained approximately 13% WO3 and approximately 15% Mo. Sulfuric acid was used for leaching, and the leachate and leaching residue were obtained after filtration and washing.

[0107] The initial concentration of sulfuric acid added to the low-grade tungsten-molybdenum ore was 88.2 g / L, the leaching solution-to-solid ratio was 15 L / kg, the leaching temperature was 98℃, the leaching time was 4 h, and after leaching and filtration, the mass concentration of (Mo+WO3) in the leaching solution was measured to be 18.53 g / L, and the sulfuric acid concentration was 48 g / L; the leaching rate of tungsten and molybdenum was approximately 99.2%.

[0108] (2) Molybdenum is selectively extracted from the leachate obtained in step (1) using a cationic extractant to obtain a tungsten-containing molybdenum extraction residue and a negative molybdenum organic phase;

[0109] The cationic extractant was Cyanex272 with a concentration of 35%, the diluent was kerosene, the oil-water ratio was O / A = 1 / 2, countercurrent extraction was used, the number of extraction stages was 8, the extraction rate of molybdenum reached 97%, and the co-extraction rate of tungsten was 0.5%.

[0110] Molybdenum was back-extracted from the negative molybdenum organic phase using 15% hydrogen peroxide as the back-extraction agent. The back-extraction ratio was O / A = 10 / 1, and the number of back-extraction stages was 4. A back-extraction solution with a Mo content of 190 g / L was obtained, which was then evaporated and decomposed to obtain molybdic acid product.

[0111] The organic relative leachate after back-extraction is recycled for selective extraction of molybdenum.

[0112] (3) Tungsten was extracted from the molybdenum extraction residue containing tungsten using a neutral extractant to obtain the tungsten extraction residue and the negative tungsten organic phase;

[0113] The neutral extractant was TBP with a concentration of 40%, the diluent was kerosene, the oil-water ratio was O / A = 1 / 2, countercurrent extraction was used, the number of extraction stages was 10, and the extraction rates of tungsten and residual molybdenum both reached over 99%.

[0114] Tungsten was back-extracted from the negative tungsten organic phase using 6 mol / L ammonia water as the back-extraction agent. The back-extraction ratio was O / A = 8 / 1, and the number of back-extraction stages was 5. The back-extraction solution with WO3 content of 205 g / L and Mo content of 4.7 g / L was obtained. After deep removal of molybdenum by traditional selective precipitation method, the product was obtained by evaporation and crystallization.

[0115] The organic phase after back-extraction is recycled to extract tungsten from the tungsten-containing molybdenum extraction residue;

[0116] (4) Part of the tungsten extraction residue from step (3) is returned to step (1) for recycling, and part of it is opened into the wastewater treatment system.

[0117] Comparative Example 1

[0118] Low-grade tungsten-molybdenum ore was used as raw material. The raw ore contained approximately 10% WO3 and 3% Mo. Sulfuric acid leaching was employed, and the leachate and leaching residue were obtained after filtration and washing.

[0119] The initial sulfuric acid concentration was 0.9 mol / L, the leaching liquid-to-solid ratio was 15 L / kg, the leaching temperature was 98℃, and the leaching time was 4 hours. The leaching was followed by filtration. Due to insufficient molybdenum content to achieve complex leaching of tungsten, the tungsten leaching rate was only 25%.

[0120] 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 tungsten and molybdenum from low-grade tungsten-molybdenum ore, characterized in that, The method includes: (1) Low-grade tungsten-molybdenum ore was leached with sulfuric acid, and the leaching solution and leaching residue were obtained by solid-liquid separation; (2) Molybdenum is extracted from the leachate using a cationic extractant to obtain a molybdenum-containing residual liquid containing tungsten and a negative molybdenum organic phase; molybdenum is back-extracted from the negative molybdenum organic phase using a back-extractant to obtain a molybdenum-containing back-extractant; (3) Tungsten is extracted from the tungsten-containing molybdenum extraction residue using a neutral extractant to obtain a tungsten extraction residue and a negative tungsten organic phase; tungsten is back-extracted from the negative tungsten organic phase using a back-extractant to obtain a tungsten-containing back-extractant; The low-grade tungsten-molybdenum ore contains 5%-30% Mo+WO3; the mass ratio of Mo / WO3 in the low-grade tungsten-molybdenum ore is greater than 2 / 3. The leaching is atmospheric pressure leaching, and the molybdenum in the low-grade tungsten-molybdenum ore undergoes complexation with tungsten to generate molybdenum isopolyacids or tungsten-molybdenum heteropolyacids. In the leachate, the mass concentration of Mo+WO3 is not higher than 30 g / L, and the sulfuric acid concentration is 20-50 g / L; The stripping agent used for stripping tungsten from the negative tungsten organic phase is ammonia.

2. The method according to claim 1, characterized in that, The percentage content of Mo+WO3 in the low-grade tungsten-molybdenum ore is 10%-30%.

3. The method according to claim 1, characterized in that, The low-grade tungsten-molybdenum ore has a Mo / WO3 mass percentage greater than 1 / 1.

4. The method according to claim 1, characterized in that, The low-grade tungsten-molybdenum ore contains calcium molybdate, calcium tungstate, calcium fluoride, calcium carbonate, and magnesium carbonate.

5. The method according to claim 1, characterized in that, In step (1), the leaching liquid-to-solid ratio is 10L / kg-30L / kg.

6. The method according to claim 1, characterized in that, In step (1), the leaching temperature is 80-100℃ and the time is 2-6h.

7. The method according to claim 1, characterized in that, In step (1), the mass concentration of Mo+WO3 in the leachate is 5~30g / L and the concentration of sulfuric acid is 30-50g / L.

8. The method according to claim 1, characterized in that, In step (2), the cationic extractant is one or more of P204, P507 and Cyanex272, and the diluent is kerosene. The volume concentration of the cationic extractant solution is 20%-40%.

9. The method according to claim 1, characterized in that, In step (3), the neutral extractant is tributyl phosphate and the diluent is kerosene, wherein the volume concentration of the neutral extractant solution is 20%-40%.

10. The method according to claim 1, characterized in that, The method also includes recycling the organic phase obtained after back-extraction back to the extraction step.

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