A method for high-efficiency separation of tungsten and tin by low-grade tungsten-tin alkaline method

Abstract

This application provides a method for efficient alkaline separation of low-grade tungsten-tin ore, comprising: placing a mixture of sodium hydroxide solution and low-grade tungsten-tin ore in a high-pressure reactor for pressurized and heated leaching; after leaching, cooling and filtering to obtain detungsten-removed slag and leachate; performing countercurrent extraction of the leachate using an extractant, wherein the oil-water ratio of the leachate to the extractant is 1 / 10 to 1 / 1; and obtaining a loaded organic phase and raffinate after phase separation, wherein the extractant comprises: 10-40 wt% methyl carbonate quaternary ammonium salt, 5-15 wt%... Isooctyl alcohol or 2-octanol (wt%) was used as a phase modifier and kerosene as a diluent. The loaded organic phase was first washed countercurrently with 5-30 g / L sodium hydroxide solution, and after phase separation, the washed organic phase and washing solution were obtained. The washed organic phase was back-extracted with a mixed solution of 1-4 mol / L ammonium bicarbonate and 0.5-3 mol / L ammonia water to obtain a back-extraction solution, wherein the oil-water ratio was 10 / 1-30 / 1. The back-extraction solution was de-oiled using resin. The de-oiled back-extraction solution was directly evaporated and crystallized to obtain ammonium paratungstate product and crystallization mother liquor.

Description

Technical Field

[0001] This application relates to the field of metal extraction technology, and in particular to a method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten and tin. Background Technology

[0002] Tin and tungsten play indispensable roles as key elements in modern technology and manufacturing. Tungsten, an important strategic metal and a crucial component of high-tech new materials, is widely used in electronic optical materials, special alloys, functional materials, and organometallic compounds. It is applied in communications, computers, aerospace, medical, photosensitive, optoelectronic, energy, and catalyst fields, and is one of the nation's key resources. Tin, as a low-melting-point metal, is widely used in electronic equipment, packaging materials, and the welding industry. The increasing importance of tin and tungsten has prompted in-depth research and optimization of tin-tungsten ore beneficiation and smelting technologies. However, the complex mineral composition of tin-tungsten ores and other associated minerals make their beneficiation process exceptionally complex. How to efficiently recover tin and tungsten has become a common challenge for both scientific research and industry.

[0003] Due to the importance of these metals, although the content in low-grade tungsten-tin ore is far below the economically exploitable standard, it still has development potential and value, especially as high-grade resources gradually decrease. Tungsten ore extraction typically employs gravity separation, flotation, or a combination of both. However, for associated tungsten in complex and difficult-to-process tin concentrates, beneficiation methods are insufficient for separation. Therefore, smelting processes can be used to separate tungsten and tin from tungsten-tin ore, further improving tungsten and tin recovery rates and increasing economic benefits.

[0004] Patent CN201910159646.7 discloses a method for preparing ammonium paratungstate from tungsten ore using a combination of acid and alkali treatment: First, tungsten ore is mixed with hydrochloric acid and hydrogen peroxide to obtain solid tungstic acid and an acid decomposition mother liquor; then, the solid tungstic acid is dissolved with sodium carbonate and filtered to obtain a dissolving residue and a sodium tungstate solution; then, the sodium tungstate solution is neutralized with sulfuric acid to a specific pH to prepare a pre-exchange solution; tungsten is adsorbed using a macroporous weakly basic anion exchange resin, turning the pre-exchange solution into a post-exchange solution containing sodium sulfate, and the resin is washed; finally, the resin adsorbing the tungsten is desorbed with ammonia to obtain an ammonium tungstate eluent, which is then purified by evaporation and crystallization to obtain the ammonium paratungstate product. However, this method has the following problems: 1. Hydrogen peroxide is unstable and easily decomposes. If the decomposition rate is too fast during the reaction, it may lead to incomplete reaction, ultimately affecting the product yield and quality. 2. Ammonia is volatile and produces a pungent odor. Furthermore, if the desorption conditions (such as temperature, ammonia concentration, and desorption time) are not properly controlled, it may lead to incomplete desorption or an increase in the impurity content in the desorption solution, affecting the quality of ammonium paratungstate products.

[0005] Patent CN202010767997.9 discloses a two-step acid decomposition method for extracting tungsten. This method includes the following steps: (1) using a first acid with a controlled H+ concentration of 0.1-4.0 mol / L to decompose tungsten ore or a crude sodium tungstate solution to obtain crude tungstic acid; wherein polyethylene glycol is added during the acid decomposition process; (2) dissolving the crude tungstic acid in ammonia or ammonium carbonate solution to obtain a crude ammonium tungstate solution, then adding a second acid or introducing carbon dioxide for secondary acid decomposition to separate tungstic acid and ammonium salt solutions. The tungstic acid is then dissolved again in ammonia to obtain an ammonium tungstate solution, which is then evaporated and crystallized to obtain ammonium paratungstate. This method involves numerous steps, resulting in high production costs and long processing times. Furthermore, due to the multiple acid decomposition and dissolution steps, numerous intermediate products are generated, which can easily affect the purity and quality of the product.

[0006] Based on the existing difficulties in beneficiating low-grade tungsten-tin ore and the challenges in separating tungsten and tin, a smelting process using pressurized selective alkaline decomposition of tungsten in tungsten-tin ore is proposed. This process aims to improve the recovery rate of tungsten and tin in the tungsten-tin separation process of low-grade tungsten-tin ore beneficiation, reduce beneficiation costs, and directly extract tungsten from low-grade tungsten-tin ore, thus solving the problem of difficult tungsten-tin separation in beneficiation. Summary of the Invention

[0007] The purpose of this invention is to solve the above-mentioned problems and provide a method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten and tin.

[0008] The technical solution of this application is implemented as follows: This invention provides a method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten and tin, comprising the following steps: S1, Leaching of tungsten-tin ore: A mixture of sodium hydroxide solution and low-grade tungsten-tin ore is placed in a high-pressure reactor for pressurized and heated leaching. After leaching, the mixture is cooled and filtered to obtain tungsten-removed slag and leachate. S2, Extraction: The leachate is subjected to countercurrent extraction using an extractant, and the oil-water ratio of the leachate to the extractant is 1 / 10 to 1 / 1. After extraction, the phases are separated to obtain a loaded organic phase and a raffinate. The extractant includes: 10 to 40 wt% of methyl carbonate quaternary ammonium salt, 5 to 15 wt% of isooctanol or sec-octanol as a phase modifier, and kerosene as a diluent. S3, Washing: The supported organic phase is first washed countercurrently with 5~30g / L sodium hydroxide solution, with an oil-water ratio of 3 / 1~10 / 1 and 3~5 stages. After phase separation, the washed organic phase and washing liquid are obtained. S4, back-extraction: The washed organic phase is back-extracted with a mixed solution of 1~4 mol / L ammonium bicarbonate and 0.5~3 mol / L ammonia water to obtain a back-extraction solution, wherein the oil-water ratio is 10 / 1~30 / 1; S5, Degreasing: The back-extraction solution is degreased using resin; S6, Evaporation and Crystallization: The stripping solution after oil removal is directly evaporated and crystallized to obtain ammonium paratungstate product and crystallization mother liquor.

[0009] As a further improvement, in step S1, the specific parameters for placing the mixed slurry of sodium hydroxide solution and low-grade tungsten-tin ore in a high-pressure reactor for pressurization and heating leaching include: Sodium hydroxide concentration is 150~250 g / L, liquid-to-solid ratio is 1~4 m 3 / t, temperature 140~220℃, time 0.5~10h, pressure 0.3~1 MPa, leachate pH about 13~14.

[0010] As a further improvement, in step 2, the extractant comprises: 15-25 wt% methyl carbonate quaternary ammonium salt, 8-12 wt% isooctanol or sec-octanol as a phase modifier, and the remainder is kerosene.

[0011] As a further improvement, in step S2, the raffinate is replenished with sodium hydroxide solution and then returned to step S1.

[0012] As a further improvement, in step S3, the washing solution is replenished with sodium hydroxide solution and then returned to step S1.

[0013] As a further improvement, in step S6, the crystallization mother liquor is replenished with ammonia and ammonium bicarbonate and then returned to step S4 for reuse.

[0014] As a further improvement, in step S2, the countercurrent extraction of the leachate using an extractant specifically includes: The leachate was subjected to 1 to 8 stages of countercurrent extraction using an extractant.

[0015] As a further improvement, the leachate is subjected to 5-6 stages of countercurrent extraction using an extractant.

[0016] The advantages or beneficial effects of the above technical solutions include at least the following: This invention utilizes high-concentration sodium hydroxide to decompose tungsten-containing minerals in low-grade tungsten-tin ore. After liquid-solid separation, tin remains in the solid phase and can be further refined into tin concentrate for sale. Tungsten enters the solution as sodium tungstate, which can be directly extracted with methyl carbonate quaternary ammonium salt extractant for tungsten-molybdenum extraction. The raffinate contains a high level of hydroxide ions, which can be used as a leaching agent in the direct sodium hydroxide leaching process. The loaded organic phase is washed with weakly alkaline sodium hydroxide, and the washing liquid can also be returned to the leaching process as a leaching agent. After washing, the loaded organic phase is eluted with ammonium bicarbonate and ammonia water. The elution solution is an ammonium tungstate solution, which can be evaporated and crystallized to obtain ammonium paratungstate product. This invention effectively reduces the cost of tungsten-tin separation from low-grade tungsten-tin ore, has a short process flow, and reduces wastewater discharge. Attached Figure Description

[0017] The accompanying drawings illustrate exemplary embodiments of the present application and, together with the description thereof, serve to explain the principles of the present application. These drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification.

[0018] Figure 1 A flowchart of a method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten and tin, provided in an embodiment of the present invention, is shown. Detailed Implementation

[0019] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While some embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this application. It should be understood that the drawings and embodiments of this application are for illustrative purposes only and are not intended to limit the scope of protection of this application.

[0020] It should be noted that, where there is no conflict, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] The names of the messages or information exchanged between multiple devices in the embodiments of this application are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0022] Reference Figure 1 This invention provides a method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten and tin, comprising the following steps: S1, Leaching of tungsten-tin ore: A mixture of sodium hydroxide solution and low-grade tungsten-tin ore is placed in a high-pressure reactor for pressurized and heated leaching. After leaching, the mixture is cooled and filtered to obtain tungsten-removed slag and leachate. S2, Extraction: The leachate is subjected to countercurrent extraction using an extractant, and the oil-water ratio of the leachate to the extractant is 1 / 10 to 1 / 1. After extraction, the phases are separated to obtain a loaded organic phase and a raffinate. The extractant includes: 10 to 40 wt% of methyl carbonate quaternary ammonium salt, 5 to 15 wt% of isooctanol or sec-octanol as a phase modifier, and kerosene as a diluent. S3, Washing: The supported organic phase is first washed countercurrently with 0.1~1 mol / L sodium hydroxide solution, with an oil-to-water ratio of 3 / 1~10 / 1 and 3~5 stages. After phase separation, the washed organic phase and washing solution are obtained. S4, back-extraction: The washed organic phase is back-extracted with a mixed solution of 1~4 mol / L ammonium bicarbonate and 0.5~3 mol / L ammonia water to obtain a back-extraction solution, wherein the oil-water ratio is 10 / 1~30 / 1; S5, Degreasing: The back-extraction solution is degreased using resin; S6, Evaporation and Crystallization: The stripping solution after oil removal is directly evaporated and crystallized to obtain ammonium paratungstate product and crystallization mother liquor.

[0023] As a further improvement, in step S1, the specific parameters for placing the mixed slurry of sodium hydroxide solution and low-grade tungsten-tin ore in a high-pressure reactor for pressurization and heating leaching include:

[0024] Sodium hydroxide concentration is 150~250 g / L, liquid-to-solid ratio is 1~4 m 3 The process involves leaching at a temperature of 140–220°C for 0.5–10 hours, a pressure of 0.3–1 MPa, and a leachate pH of approximately 13–14. More preferably, the sodium hydroxide concentration is 150–250 g / L, and the liquid-to-solid ratio is 1–4 m³ / L. 3 / t, temperature 150~200℃, time 1~5h, pressure 0.4~0.7 MPa, leachate pH about 13~14.

[0025] The coupling of high-concentration NaOH (150–250 g / L) with temperatures of 140–220 °C causes tungsten minerals (scheelite, wolframite, and their associated tungstates) to preferentially transform thermodynamically into soluble Na₂WO₄, while cassiterite (SnO₂) hardly reacts under these strong alkaline-high-temperature conditions and remains in a solid phase. Furthermore, applying pressure of 0.3–1 MPa raises the boiling point of the solution, avoiding the sudden drop in alkali concentration caused by evaporation under normal pressure; simultaneously, the liquid-to-solid ratio is 1–4 m³ / L. 3 / t Ensure sufficient alkali content so that the particle surface is always in a state of free OH- - The supersaturated state eliminates solid-film diffusion resistance, achieving an equilibrium leaching rate of over 90% within 0.5 hours. Furthermore, impurities commonly found in low-grade ore (WO3), such as Ca, F, P, and As, remain in the slag or solution as Ca(OH)2, CaF2, Na3PO4, and Na3AsO4 respectively under high alkalinity (pH 13–14), preventing them from entering the subsequent organic phase and reducing the risk of emulsification in the extraction stage. Stable operation is still possible even for fine-grained slurries with a particle size <74μm accounting for more than 60%, requiring no additional roasting pretreatment. Finally, the strong alkaline environment inhibits the hydrolysis of silicates and aluminates, resulting in a SiO2 leaching rate <0.5% and Al2O3 <0.3%, thus ensuring a clean interface in the subsequent extraction stage. The phase separation time is shortened from the conventional 5–8 min to 1–2 min, and the organic phase loss is reduced by 60%.

[0026] As a further improvement, in step 2, the extractant comprises: 15-25 wt% methyl carbonate quaternary ammonium salt, 8-12 wt% isooctanol or sec-octanol as a phase modifier, and the remainder being kerosene. Preferably, 18-20 wt% methyl carbonate quaternary ammonium salt, 9-11 wt% isooctanol or sec-octanol as a phase modifier, and the remainder being kerosene.

[0027] The quaternary ammonium salt of methyl carbonate (QAC-COOCH3) possesses both a quaternary ammonium cation and a polar methyl ester group. In a strongly alkaline solution with a pH of 13-14, it can react with WO4. 2- It forms a 1:2 ion-pair complex with a saturation capacity of 22-25 g WO3 / L organic phase, which is more than 30% higher than that of traditional methyltrialkylammonium chloride. Therefore, even with an extremely low oil / water ratio of 1 / 1–1 / 10, a single extraction rate of ≥98% can still be achieved, reducing organic inventory by 40%. Furthermore, the steric hindrance of the ester group and the charge shielding effect of quaternary ammonium make Sn(OH)6... 2- AsO4 3- PO4 3- The partition coefficient of impurity anions is higher than that of WO4. 2- The WO3 / Sn mass ratio in the measured raffinate is reduced by 1–2 orders of magnitude; the measured WO3 / Sn mass ratio in the raffinate increases from 3–5 times that of the feed to over 200 times, and the As and P co-extraction rate is <1%, directly eliminating the need for the subsequent "tungsten-tin-arsenic" purification process. Furthermore, 8–12 wt% isooctol / sec-octanol, as a phase modifier, can reduce the viscosity of the organic phase from 6.5 mPa·s to 2.8 mPa·s and the interfacial tension to 8–10 mN / m, forming fine and stable droplets. Compared to the traditional 20% high-carbon alcohol system, the mass transfer coefficient k... La The efficiency is increased by 50%; over 98% of the theoretical extraction efficiency can be achieved with 5-6 stages of countercurrent extraction, thus reducing the equipment volume by 30%. Finally, the methyl ester group undergoes only <2% / month saponification under strong alkaline washing (0.1~1 mol / L NaOH), far lower than the 10% / month degradation rate of phosphate ester extractants; after 50 cycles, the saturation capacity of the organic phase decreases by <3%, and the interfacial tension changes by <5%, eliminating the need for frequent replacement or regeneration.

[0028] As a further improvement, in step S2, the countercurrent extraction of the leachate using an extractant specifically includes: The leachate was subjected to 1 to 8 stages of countercurrent extraction using an extractant.

[0029] As a further improvement, the leachate is subjected to 5-6 stages of countercurrent extraction using an extractant.

[0030] As a further improvement, in step S2, the raffinate is replenished with sodium hydroxide solution and then returned to step S1.

[0031] As a further improvement, in step S3, preferably, the supported organic phase is first countercurrently washed with a 10-20 g / L sodium hydroxide solution at an oil-to-water ratio of 5 / 1-10 / 1, with 3-5 washing stages. After phase separation, the washed organic phase and washing liquid are obtained. This low-concentration alkaline solution only provides OH... - Concentration gradient without disrupting WO4 2- Quaternary ammonium salt ion-paired compounds; however, for co-extracted Sn(OH)6 2- ,HAsO4 2- PO4 3- SiO4 4- Impurity anions, because their binding affinity to quaternary ammonium salts is weaker than that of WO4. 2- In 3–5 stages of backwashing, tin is selectively displaced. Furthermore, tin in the organic phase is represented as Sn(OH)6. 2- With weak coordination and a high O / A ratio of ≥3 / 1, 80-90% of the co-extracted tin can be backwashed into the aqueous phase, preventing tin from entering the APT along with tungsten in the subsequent back-extraction stage, thus completely solving the problem of Sn content >30 ppm in APT products. Furthermore, the low alkali concentration avoids ester saponification, the interfacial tension of the organic phase is maintained at 8-10 mN / m, the phase separation time is 30-60 s, and there is no emulsification or third phase. After 30 days of continuous operation, the viscosity of the organic phase increases by <5%, requiring no phase modifier.

[0032] As a further improvement, in step S3, the washing solution is replenished with sodium hydroxide solution and then returned to step S1. The WO3 and NaOH contained in the washing solution are directly returned to the high-pressure leaching section, which not only recovers trace amounts of tungsten but also utilizes the residual alkali, achieving integrated "washing-leaching" with zero discharge of washing solution.

[0033] As a further improvement, in step S3, the washed organic phase is back-extracted using a mixed solution of 2-4 mol / L ammonium bicarbonate and 1-2 mol / L ammonia water to obtain a back-extraction solution, wherein the oil-to-water ratio is 5 / 1 to 10 / 1.

[0034] The ammonium bicarbonate-ammonia conjugate buffer system maintains a stable free NH3 concentration of 0.5–1.5 mol / L within the pH range of 9.2–9.8, undergoing transient ion exchange with (R4N)2WO4 in the supported organic phase, with an apparent back-extraction rate constant k ≥ 0.35 min. -1This method improves efficiency by 40% compared to a single ammonia-water system; the back-extraction rate can be ≥99% with 1-2 stages of countercurrent at 25-40℃, and the residual WO3 in the organic phase is <0.1 g / L. Furthermore, the high oil-water ratio (10 / 1-30 / 1) makes the volume of the aqueous phase only 3-10% of the organic phase, with a density difference Δρ ≥0.25 g / cm³. 3 With a viscosity difference Δμ ≥ 1.5 mPa·s, a "thin water layer - thick oil layer" state is formed, and the centrifugal phase separation time is ≤ 45 s, with no entrainment or emulsification, eliminating the need for a coalescer. Furthermore, ammonium bicarbonate chemically binds ammonia (NH4+). + NH3+ H + This reduces the partial pressure of free ammonia by 60%; under normal operating conditions at 40℃, the NH3 concentration at the exhaust port is <15mg / m³. 3 It is 20 mg / m³ lower than the secondary limit of the "Odor Pollutant Emission Standard" (GB 14554-93). 3 There was no pungent odor on site, eliminating the need for an ammonia scrubbing tower. Finally, after 50 cycles, the cumulative tungsten loss in the organic phase was less than 1%, and the direct recovery rate of WO3 throughout the process was 5–7 percentage points higher than that of the traditional acid-base combined process.

[0035] As a further improvement, in step S6, the crystallization mother liquor is replenished with ammonia and ammonium bicarbonate and then returned to step S4 for reuse. The crystallization mother liquor can be returned to the back-extraction section by adding a small amount of solid NH4HCO3 and ammonia, achieving 100% reuse of the ammonia-carbonate system; the system discharges no ammonia-containing wastewater, and ammonia consumption is reduced from the traditional 0.25 t NH3 / t APT to 0.05 t NH3 / t APT.

[0036] Example 1: Taking a certain tungsten-tin mine as an example, the tungsten trioxide content in the ore is 6.27%, and the tin content is 4.21%.

[0037] Weigh 500g of tin ore of the original particle size, add 2L of 200 g / L sodium hydroxide solution, heat to 200℃ in a pressure cooker, keep warm and stir for 5 h, and maintain the pressure at 0.6MPa. After liquid-solid separation, obtain tin slag and sodium tungstate leachate. The pH of the leachate is about 13.5.

[0038] The tin dross was washed and weighed, with a weight of 431.25g, of which tungsten trioxide content was 0.42% and tin content was 4.88%.

[0039] The extractant composition is 20% methyl carbonate quaternary ammonium salt + 10% isooctyl alcohol + 70% kerosene. It can be directly used to extract sodium tungstate solution without conversion. The oil-water ratio is 1 / 5, the extraction stage is 6, and the pH of the raffinate is 13.56.

[0040] Washing: The above-mentioned loaded organic material was first washed with 20 g / L sodium hydroxide solution, with an oil-to-water ratio of 5:1 and a washing stage of 3, and then washed with pure water, with an oil-to-water ratio of 5:1 and a washing stage of 2.

[0041] Back-extraction: After washing, the organic material is back-extracted using a mixed solution of 3 mol / L ammonium bicarbonate and 1 mol / L ammonia water, with an oil-to-water ratio of 5 / 1 and 5 extraction stages.

[0042] After the back-extraction solution was degreased through a resin, it was directly evaporated and crystallized to obtain 30.41g of ammonium paratungstate.

[0043] Add 130g of sodium hydroxide to the raffinate, weigh out 500g of tungsten-tin ore of the original particle size, add raffinate to 2L, heat to 200℃ in a pressure cooker, keep warm and stir for 5 hours, and obtain tin slag and sodium tungstate leachate by liquid-solid separation.

[0044] The tin dross was washed and weighed, with a weight of 428.52g, of which tungsten trioxide content was 0.41% and tin content was 4.91%.

[0045] This invention achieves the following effects by using high-concentration sodium hydroxide to decompose tungsten-containing minerals in low-grade tungsten-tin ore: Firstly, low-grade tungsten-tin ore is often enriched through beneficiation processes, and tungsten and tin are usually separated by flotation or gravity separation. However, the separation efficiency and recovery rate of tungsten and tin are low. This invention extracts tungsten from low-grade tungsten-tin ore through smelting processes, which can further improve the tin grade. At the same time, the tungsten-containing solution can be directly used to produce tungsten products, reducing the number of processes involved in beneficiation and smelting of tungsten and tin, improving the overall recovery rate of tungsten and tin in low-grade tungsten-tin ore, and reducing costs.

[0046] Secondly, the conversion of sodium tungstate solution to ammonium tungstate is often achieved using strongly alkaline anion exchange resins. However, the pre-exchange solution requires a sodium hydroxide concentration of less than 10 g / L, a WO3 concentration of 15-20 g / L, and a chloride ion concentration of less than 0.8 g / L. However, low-grade tungsten-tin ore is leached with sodium hydroxide, resulting in a high sodium hydroxide content and low tungsten content in the solution. If hydrochloric acid is used to adjust the pH, the excessively high chloride ion content will compete with tungsten for adsorption during the adsorption process, preventing the tungsten in the solution from being converted through the resin. Using methyl carbonate quaternary ammonium salt extractant can extract tungsten from the solution under strongly alkaline conditions. Simultaneously, excess hydroxide ions in the raffinate can be recycled as a leaching reagent after adding sodium hydroxide, further reducing the amount of reagents used in the process. This process generates virtually no wastewater; both ammonia-containing and hydroxide-containing solutions are returned to the process as intermediate products.

[0047] Those skilled in the art should understand that the above embodiments are merely for illustrative purposes and are not intended to limit the scope of this application. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of this application.

Claims

1. A method for high efficient separation of tungsten and tin from low-grade tungsten-tin alkali method, characterized in that, Includes the following steps: S1, Leaching of tungsten-tin ore: A mixture of sodium hydroxide solution and low-grade tungsten-tin ore is placed in a high-pressure reactor for pressurized and heated leaching. After leaching, the mixture is cooled and filtered to obtain tungsten-removed slag and leachate. S2, Extraction: The leachate is subjected to countercurrent extraction using an extractant, and the oil-water ratio of the leachate to the extractant is 1 / 10 to 1 / 1. After extraction, the phases are separated to obtain a loaded organic phase and a raffinate. The extractant includes: 10 to 40 wt% of methyl carbonate quaternary ammonium salt, 5 to 15 wt% of isooctanol or sec-octanol as a phase modifier, and kerosene as a diluent. S3, Washing: The supported organic phase is first washed countercurrently with 5~30g / L sodium hydroxide solution, with an oil-water ratio of 3 / 1~10 / 1 and 3~5 stages. After phase separation, the washed organic phase and washing liquid are obtained. S4, back-extraction: The washed organic phase is back-extracted with a mixed solution of 1~4 mol / L ammonium bicarbonate and 0.5~3 mol / L ammonia water to obtain a back-extraction solution, wherein the oil-water ratio is 10 / 1~30 / 1; S5, Degreasing: The back-extraction solution is degreased using resin; S6, Evaporation and Crystallization: The stripping solution after oil removal is directly evaporated and crystallized to obtain ammonium paratungstate product and crystallization mother liquor.

2. The method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten-tin according to claim 1, characterized in that, In step S1, the specific parameters for placing the mixed slurry of sodium hydroxide solution and low-grade tungsten-tin ore in a high-pressure reactor for pressurization and heating leaching include: The concentration of sodium hydroxide is 150-250 g / L, and the liquid-solid ratio is 1-4 m 3 The temperature is 140-220℃, the time is 0.5-10h, the pressure is 0.3-1 MPa, and the pH of the leaching solution is about 13-14.

3. The method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten-tin according to claim 1, characterized in that, In step 2, the extractant comprises: 15-25 wt% methyl carbonate quaternary ammonium salt, 8-12 wt% isooctanol or sec-octanol as a phase modifier, and the remainder is kerosene.

4. The method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten-tin according to claim 1, characterized in that, In step S2, the raffinate is replenished with sodium hydroxide solution and then returned to step S1.

5. The method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten-tin according to claim 1, characterized in that, In step S3, the washing solution is replenished with sodium hydroxide solution and then returned to step S1.

6. The method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten-tin according to claim 1, characterized in that, In step S6, the crystallization mother liquor is replenished with ammonia and ammonium bicarbonate and then returned to step S4 for reuse.

7. The method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten-tin according to claim 1, characterized in that, In step S2, the countercurrent extraction of the leachate using an extractant specifically includes: The leachate was subjected to 1 to 8 stages of countercurrent extraction using an extractant.

8. The method for efficient separation of tungsten and tin using an alkaline process for low-grade tungsten-tin according to claim 7, characterized in that, The leachate was subjected to 5-6 stages of countercurrent extraction using an extractant.

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