Comprehensive treatment method of scheelite

Abstract

The invention provides a comprehensive treatment method of scheelite, and relates to the technical field of mineral treatment. Specifically, the method comprises the following steps: preparing a dispersion liquid containing scheelite, hydrochloric acid and an adsorbent (including at least one of an extraction agent or adsorption resin); performing ultrasonic treatment or microwave treatment on the dispersion liquid at 60-80 DEG C to obtain a mixed phase; standing the mixed phase, and separating to obtain an inorganic precipitate and an organic phase; sequentially carrying out ammonia dissolution treatment, anion resin purification treatment and evaporative crystallization treatment on the inorganic precipitate to obtain ammonium paratungstate; the organic phase is sequentially subjected to one of reverse extraction treatment or analysis treatment, and then a calcium product is obtained through separation. According to the method, the tungsten extraction efficiency is effectively improved, the negative influence of a tungsten wrapping layer in scheelite on acid leaching is reduced, and effective recovery and reutilization of calcium resources are achieved; the scheelite treatment cost is reduced, the resource utilization rate is increased, and the environmental pollution is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral processing, and more particularly, to a comprehensive treatment method for scheelite. Background Art

[0002] The leaching of scheelite is an important step in the tungsten smelting process. The main purpose is to extract the tungsten element in scheelite through chemical reactions and convert it into a soluble tungstate solution for subsequent further purification and processing. The current scheelite leaching generally adopts two categories: alkali method and acid method. There are also methods such as soda sintering - water leaching method and fluoride salt leaching method, but they are not commonly used. Specifically, the commonly used leaching agents for alkali method leaching are NaOH and Na2CO3. Among them, the NaOH alkali pressure cooking process is widely used, and the leaching rate can reach 98% - 99% when treating scheelite concentrate. It has the advantages of short process and high leaching rate, but has the disadvantages of high energy consumption and high reagent dosage. Correspondingly, the commonly used leaching agents for acid method leaching are hydrochloric acid, nitric acid, sulfuric - phosphoric mixed acid, etc. The sulfuric - phosphoric mixed acid synergistic leaching technology has gradually increased its market share due to advantages such as low cost and environmental protection. The leaching effects of the above - mentioned acid method and alkali method are affected by factors such as ore properties, reagent concentration, temperature, etc. At the same time, existing technologies such as autoclave treatment and combined leaching agents can effectively increase the leaching rate of tungsten to a relatively high level, which is suitable for the treatment of low - grade complex ores or can further optimize cost and efficiency.

[0003] Furthermore, the traditional treatment process of scheelite usually includes the following processes: ball - milling of scheelite concentrate, acidolysis, filtration and washing, ammonia dissolution, impurity removal, crystallization and obtaining related products. The core reaction in the acidolysis stage (taking hydrochloric acid as an example) is: CaWO4 + 2HCl——H2WO4 + CaCl2, where H2WO4 precipitates out. However, the tungstic acid (H2WO4) generated by the above reaction often wraps on the surface of unreacted CaWO4, forming a diffusion barrier, resulting in a reduced reaction rate (≤85%). In addition, high - concentration hydrochloric acid (>5mol / L) and high - temperature conditions will exacerbate acid mist emissions, along with equipment corrosion and environmental pollution problems. Moreover, existing technologies only focus on the extraction of tungsten and do not effectively recover calcium resources. As an important component in scheelite, calcium enters the solution in ionic form during acid leaching and then is discharged with the waste liquid, causing resource waste and possibly having a certain impact on the environment.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The object of the present invention is to provide a comprehensive treatment method for scheelite, which is used to solve the technical defect that conventional scheelite cannot simultaneously meet the advantages of high leaching rate, low energy consumption, short process, low cost, and environmental friendliness during the acid leaching of tungsten, and at the same time, it can also solve the problem of the inability to effectively utilize calcium resources in the ore during the acid leaching of scheelite.

[0006] To achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0007] A comprehensive treatment method for scheelite includes the following steps:

[0008] (1) Prepare a dispersion liquid containing scheelite, hydrochloric acid and an adsorbent, where the adsorbent includes at least one of an extractant or an adsorption resin; perform ultrasonic treatment or microwave treatment on the dispersion liquid at 60°C to 80°C to obtain a mixed phase; after the mixed phase stands still, separate to obtain an inorganic precipitate and at least one of an organic phase or an adsorption resin;

[0009] (2) Perform ammoniacal dissolution treatment, anion resin purification treatment and evaporation crystallization treatment on the inorganic precipitate in sequence to obtain ammonium paratungstate;

[0010] (3) Perform back-extraction treatment or desorption treatment on at least one of the organic phase or the adsorption resin adsorbed with calcium with sulfuric acid, and then separate to obtain a calcium product.

[0011] In the present invention, first, the hydrochloric acid acid leaching method assisted by ultrasonic waves is adopted to break the coating layer of scheelite and accelerate the reaction kinetics. At the same time, calcium ions in the acid leaching solution are adsorbed and recovered through a cation exchange resin or an acidic extractant, promoting the continuous progress of the calcium dissolution reaction and improving the reaction efficiency; calcium tungstate in the solution after acidolysis further reacts with hydrochloric acid to form tungstic acid precipitate, and then is prepared into ammonium tungstate solution through ammoniacal dissolution method, and finally purified and evaporated and crystallized to obtain ammonium paratungstate (APT) product. In addition, calcium ions adsorbed on the adsorption resin or extractant can be obtained a high-quality calcium product through desorption / back-extraction.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] (1) In the present invention, the acid leaching process is strengthened by ultrasonic waves, effectively breaking the coating layer on the surface of scheelite, enabling calcium tungstate to fully react with hydrochloric acid, and the reaction rate constant is increased by 3 to 5 times, significantly improving the recovery rate of tungsten.

[0014] (2) In the present invention, an adsorbent is introduced to synchronously recover calcium resources, converting the originally waste calcium resources into calcium products, realizing the effective recovery and utilization of calcium resources; not only improving the resource utilization rate, but also reducing the waste liquid treatment cost and environmental pollution, with significant economic and environmental benefits.

[0015] (3) In the present invention, due to the more sufficient acid leaching reaction, the content of impurity ions such as calcium ions and iron ions in the obtained ammonium tungstate solution is reduced, so the purification step is simpler in the subsequent process of preparing APT product, and the quality of APT product is more stable.

[0016] (4) The present invention improves the acid leaching reaction rate and shortens the reaction time through the ultrasonic-enhanced acid leaching technology. Meanwhile, the recycling of calcium resources reduces the waste of raw materials and significantly lowers the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 A process flow diagram for treating scheelite of the present invention is provided. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. Conditions not specified in the examples are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0020] The present invention aims to provide a comprehensive treatment method for scheelite. There are also a large number of improved processes for leaching and extracting tungsten elements from scheelite in the prior art. For example, CN202211708659.3 discloses a method for efficiently decomposing complex low-grade scheelite at room temperature. It proposes to first ball-mill the complex low-grade scheelite and make it into a slurry, and reduce the thickness of the tungsten coating layer through ultrafine grinding, thereby improving the leaching efficiency and utilization rate of tungsten mineral resources. Another example is CN202510052364.2, which discloses a method for improving the leaching rate of low-grade scheelite. After roasting the low-grade scheelite, it is leached with sulfuric acid, and then phosphorus or ethanol is added to generate soluble heteropolyacid or dissolved tungstic acid, thereby improving the leaching rate of tungsten. For another example, CN202310396767.X discloses a method for leaching scheelite, using sulfuric acid or a mixed acid of nitric acid-hydrochloric acid for low-temperature leaching of scheelite and an acid leaching solution incomplete calcium precipitation regeneration and recycling technology, achieving more thorough leaching at low temperature and reducing environmental pollution, but having poor adaptability to raw materials. Further, CN202310396767.X also discloses a method for leaching scheelite, through processes such as ultrasonic mineralization flotation, micro-nano fine bubble beneficiation, and ultrasonic salt mixing decomposition, and cooperating with a combined inhibitor to achieve the efficient decomposition of scheelite, but this process method is complex and costly, and it is difficult to promote and apply.

[0021] To improve various defects in the above processes, the comprehensive treatment method for scheelite proposed by the present invention mainly includes the following steps (1) to (3) to achieve an efficient and environmentally friendly leaching process and solve the balance between calcium recovery and process economy; as Figure 1 shown, a simple schematic of the following steps of the present invention is given.

[0022] (1) Prepare a dispersion liquid containing scheelite, hydrochloric acid, and an adsorbent, where the adsorbent includes at least one of an extractant or an adsorption resin; perform ultrasonic treatment or microwave treatment on the dispersion liquid at 60°C to 80°C to obtain a mixed phase; after the mixed phase stands still, separate to obtain an inorganic precipitate and at least one of an organic phase or an adsorption resin. It can be understood that when using the extractant as the adsorbent, the corresponding organic phase is obtained; when using the adsorption resin as the adsorbent, the corresponding adsorption resin is obtained.

[0023] As a preferred embodiment, in the dispersion liquid, the concentration of the hydrochloric acid is 1 mol / L to 4 mol / L. It should be noted that in the present invention, the hydrochloric acid has irreplaceability. When using other common acids, such as sulfuric acid may produce precipitates with some metal ions, nitric acid has certain safety risks, phosphoric acid will cause water pollution, etc., and acids such as acetic acid and formic acid are far inferior to hydrochloric acid in terms of cost.

[0024] As a preferred embodiment, the solid-liquid ratio of scheelite, hydrochloric acid and the adsorbent is 1:(3 - 5):(3 - 5), and the unit is g / mL / mL.

[0025] As a preferred embodiment, the extractant includes at least one of P204, TBP, P507, P350 or naphthenic acid.

[0026] As a preferred embodiment, the concentration of the extractant is 5 vt.% - 20 vt.%; in some more preferred embodiments, the solvent of the extractant includes sulfonated kerosene.

[0027] As a preferred embodiment, the adsorption resin adopts a cation exchange resin. Specifically, the adsorption resin includes at least one of 001×7 resin, D001 resin, BK-001, ZGC-108 resin or S-9 resin.

[0028] As a preferred embodiment, the temperature of the ultrasonic treatment includes, but is not limited to, any one of 60, 62, 65, 68, 70, 72, 75, 78, 80 (°C) or any numerical range formed by any two of them.

[0029] As a preferred embodiment, the frequency of the ultrasonic treatment is 20 kHz - 40 kHz, the power density of the ultrasonic treatment is 50 W / L - 100 W / L, and the time of the ultrasonic treatment is 2 h - 6 h. In some alternative embodiments, the frequency of the ultrasonic state includes, but is not limited to, any one of 20, 22, 25, 28, 30, 32, 35, 38, 40 (kHz) or any numerical range formed by any two of them; the power density of the ultrasonic treatment includes, but is not limited to, any one of 50, 60, 70, 80, 90, 100 (W / L) or any numerical range formed by any two of them; the time of the ultrasonic treatment includes, but is not limited to, any one of 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 (h) or any numerical range formed by any two of them.

[0030] As a preferred embodiment, the power range of the microwave treatment is 100 W - 800 W, and the frequency of the microwave treatment is 2200 MHz - 2600 MHz or 800 MHz - 1200 MHz. In some more preferred embodiments, the frequency of the microwave treatment is 2450 MHz or 915 MHz.

[0031] In the present invention, either ultrasonic treatment or microwave treatment is adopted; wherein, the ultrasonic treatment utilizes ultrasonic waves to generate strong ultrasonic cavitation in the reaction dispersion liquid, effectively destroying the coating layer formed on the surface of scheelite, enabling the acid solution to fully contact with calcium tungstate, so as to improve the leaching reaction rate of tungsten. Correspondingly, when the microwave treatment is adopted, high energy is provided by microwaves to promote the progress of the leaching reaction; however, compared with the ultrasonic treatment, the equipment cost of the microwave treatment is higher.

[0032] Furthermore, on the basis of the above ultrasonic treatment or microwave treatment, the present invention combines the processes of acid leaching and adsorption; after leaching from calcareous scheelite, the calcium ions in the dispersion liquid are adsorbed into the extractant or adsorption resin by means of extraction or resin adsorption, promoting the continuous dissolution of calcium tungstate from scheelite. By adjusting conditions such as the acidity of the dispersion liquid, the reaction temperature, and the dosage ratio of the adsorbent, the adsorption effect of calcium ions is optimized, and the adsorption rate of calcium ions in the acid leaching solution can reach more than 95%.

[0033] As a preferred embodiment, as Figure 1 shown, after the mixed phase is allowed to stand, the mixed phase includes: the inorganic precipitate (corresponding to Figure 1 the "tungstic acid precipitate" in Figure 1 ), the aqueous phase (corresponding to Figure 1 the "acid leaching solution" in

[0034] ), and at least one of the organic phase or the adsorption resin (corresponding to Figure 1 the "loaded organic phase" or "loaded resin" in

[0034] ).

[0035] (2) The inorganic precipitate is successively subjected to ammonolysis treatment, anion resin purification treatment, and evaporation crystallization treatment to obtain ammonium paratungstate.

[0036] As a preferred embodiment, the inorganic precipitate is washed before performing the operations of this step.

[0037] As a preferred embodiment, the ammonolysis treatment includes the following steps: adding the inorganic precipitate (main component: tungstic acid precipitate) to an ammonia water solution and reacting at 60°C to 100°C to obtain an ammonium tungstate solution.

[0038] As a more preferred embodiment, the concentration of the aqueous ammonia solution is 20 vt.% to 50 vt.%.

[0039] As a more preferred embodiment, the liquid-solid ratio of the aqueous ammonia solution to the inorganic precipitate is 2.5 to 5:1, with the unit of mL / g.

[0040] When performing the ammonia dissolution treatment based on the above two preferred embodiments, in a further preferred embodiment, the concentration of the ammonium tungstate solution obtained is 180 g / L to 300 g / L.

[0041] As a preferred embodiment, the resin for the anion resin purification treatment includes at least one of D201, 201×7, D314, Amberlite 4200C, or Amberlite 400C.

[0042] As a preferred embodiment, the temperature for evaporation crystallization is 90°C to 100°C.

[0043] As a preferred embodiment, the purity of the ammonium paratungstate (APT) is ≥88.5%.

[0044] (3) Subject at least one of the organic phase adsorbed with calcium or the adsorption resin to back-extraction treatment or desorption treatment with sulfuric acid, and then separate to obtain a calcium product.

[0045] In the present invention, when the adsorbent in step (1) uses the extractant, the corresponding organic phase is obtained, and in this step (3), the corresponding back-extraction treatment is used; while when the adsorbent in step (1) uses the adsorption resin, the corresponding adsorption resin is obtained, and in this step (3), the corresponding desorption treatment is used, which conforms to the substantial naming corresponding to the operations in the art.

[0046] As a preferred embodiment, the back-extraction treatment or the desorption treatment includes the following steps: Pass a sulfuric acid reagent into the organic phase or the adsorption resin, allow the organic phase or the adsorption resin to fully contact with the sulfuric acid, so that calcium ions dissolve into the sulfuric acid solution and thus separate from the organic phase or the adsorption resin.

[0047] As a preferred embodiment, the temperature of the back-extraction treatment or the desorption treatment is 25°C to 45°C.

[0048] As a more preferred embodiment, the concentration of the sulfuric acid is 1 mol / L to 3 mol / L.

[0049] As a preferred embodiment, after the stripping treatment or the resolution treatment, it further includes: washing the calcium product to remove impurity ions, and drying to obtain the calcium product; the main component of the calcium product includes calcium sulfate dihydrate crystals, and in some embodiments, the purity of calcium sulfate in the calcium product is ≥ 95%.

[0050] As a more preferred embodiment, the washing is carried out by repeatedly washing the precipitate with hot water (such as washing 3 times with hot water), and the drying temperature is 40°C to 80°C.

[0051] Example 1

[0052] The scheelite used in this example has the chemical composition shown in Table 1 below.

[0053] Table 1

[0054]

[0055] S1. Pretreatment: The scheelite is crushed and subdivided. The scheelite is put into a ball mill and ball milled to 200 meshes to obtain the finely ground scheelite powder.

[0056] S2. Enhanced acid leaching: Prepare a hydrochloric acid solution with a concentration of 2.5 mol / L; prepare a P204 solution with a concentration of 20 vt.% (the solvent is sulfonated kerosene) as an adsorbent; input the hydrochloric acid solution, the adsorbent, and the scheelite into the reaction kettle for mixing according to the liquid-solid ratio of 5 mL:4 mL:1 g, stir at 1000 rpm until fully mixed, and then stop stirring; set the temperature of the reaction kettle to 75°C, install an ultrasonic device outside the reaction kettle, set the ultrasonic frequency to 30 kHz, the ultrasonic power to 75 W / L, and time for continuous reaction for 4 h.

[0057] S3. Separation: After the reaction is completed, pour the pulp into a centrifugal device and carry out solid-liquid separation with a centrifuge. The centrifugal speed is 3600 r / min and the centrifugal time is 15 min. After separation, a liquid phase of a loaded organic phase and an acid leaching solution, and tungstic acid precipitate are obtained.

[0058] S4. APT preparation: After washing the tungstic acid precipitate with deionized water, it is mixed in an ammonia water solution under the conditions of an ammonia water concentration of 40% (v / v), a temperature of 80°C, and a liquid-solid ratio of 4:1 to obtain an ammonium tungstate solution. The crude ammonium tungstate solution is purified by ion exchange with an anion resin D201 and evaporated and crystallized to obtain the APT product of this example, which meets the national standard of APT-0 after detection.

[0059] S5. Calcium product preparation: Using a 2 mol / L sulfuric acid solution as a stripping agent, carry out stripping at 35°C and a phase ratio O / A = 1:5 to obtain calcium sulfate precipitate; after washing 3 times with deionized water and drying, obtain the calcium sulfate product of this example.

[0060] Example 2

[0061] It is basically the same as Example 1, except that:

[0062] In step S2, the ultrasonic device is replaced with a microwave device, the microwave power is 680 W, and the frequency is 2450 MHz.

[0063] Example 3

[0064] It is basically the same as Example 1, except that:

[0065] In step S2, the ultrasonic frequency is set to 20 kHz, the ultrasonic power is 50 W / L, and the timing continues to react for 6 h.

[0066] Example 4

[0067] It is basically the same as Example 1, except that:

[0068] In step S2, the ultrasonic frequency is set to 40 kHz, the ultrasonic power is 100 W / L, and the timing continues to react for 2 h.

[0069] Example 5

[0070] It is basically the same as Example 1, except that:

[0071] In step S2, the adsorbent is replaced with 001×7 type resin.

[0072] Record the purities of the APT products and calcium sulfate products obtained in S4 and S5 in each example; and refer to the scheelite element composition in Table 1 to calculate the recovery rates of tungsten and calcium. The results are recorded in Table 2 below. As can be seen from Table 2, the comprehensive treatment method of the present invention has good recovery rates of tungsten and calcium, and both have relatively high purities, showing good economic benefits.

[0073] Table 2

[0074] APT purity Tungsten recovery rate Calcium sulfate purity Calcium recovery rate Example 1 ＞88.5％ 90％ ≥95.0％ 89％ Example 2 ＞88.5％ 92％ ≥95.0％ 92％ Example 3 ＞88.5％ 85％ ≥95.0％ 84％ Example 4 ＞88.5％ 89％ ≥95.0％ 88％ Example 5 ＞88.5％ 90％ ≥95.0％ 90％

[0075] Although the present invention has been illustrated and described with reference to specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; those of ordinary skill in the art should understand that: without departing from the spirit and scope of the present invention, the technical solutions described in the foregoing embodiments can be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A comprehensive treatment method for scheelite, characterized in that, It includes the following steps: (1) Prepare a dispersion liquid containing scheelite, hydrochloric acid and an adsorbent, where the adsorbent includes at least one of an extractant or an adsorption resin; perform ultrasonic treatment or microwave treatment on the dispersion liquid at 60°C to 80°C to obtain a mixed phase; after the mixed phase stands still, separate to obtain an inorganic precipitate and at least one of an organic phase or an adsorption resin; (2) Sequentially perform ammonolysis treatment, anion resin purification treatment and evaporation crystallization treatment on the inorganic precipitate to obtain ammonium paratungstate; (3) Perform back-extraction treatment or desorption treatment on at least one of the organic phase or the adsorption resin adsorbed with calcium with sulfuric acid, and then separate to obtain a calcium product.

2. The integrated treatment method of scheelite according to claim 1, wherein, In step (1), the solid-liquid ratio of the scheelite, the hydrochloric acid and the adsorbent is 1:(3 - 5):(3 - 5), with the unit of g / mL / mL.

3. The integrated treatment method of scheelite according to claim 2, characterized in that In step (1), the concentration of the hydrochloric acid is 1 mol / L to 4 mol / L; and / or, the concentration of the extractant is 5 vt.% to 20 vt.%.

4. The integrated treatment method of scheelite according to claim 1, characterized in that, In step (1), the extractant includes at least one of P204, TBP, P507, P350 or naphthenic acid; and / or, the adsorption resin includes at least one of 001×7 type resin, D001 resin, BK-001, ZGC-108 type resin or S-9 type resin.

5. The integrated treatment method of scheelite according to claim 1, characterized in that, In step (1), the frequency of the ultrasonic treatment is 20 kHz to 40 kHz, the power density of the ultrasonic treatment is 50 W / L to 100 W / L, and the time of the ultrasonic treatment is 2 h to 6 h.

6. The comprehensive treatment method of scheelite according to claim 1, characterized in that, In step (1), the power of the microwave treatment is 100 W to 800 W, and the frequency of the microwave treatment is 2200 MHz to 2600 MHz or 800 MHz to 1200 MHz.

7. The integrated treatment method of scheelite according to claim 1, characterized in that, In step (2), the ammonolysis treatment includes the following steps: Add the inorganic precipitate into an ammonia water solution and react at 60°C to 100°C to obtain an ammonium tungstate solution; Preferably, the concentration of the ammonia water solution is 20 vt.% to 50 vt.%; preferably, the liquid-solid ratio of the ammonia water solution to the inorganic precipitate is 2.5 - 5:1, in mL / g.

8. The comprehensive treatment method of scheelite according to claim 1, characterized in that In step (2), the resin for the anion resin purification treatment includes at least one of D201, 201×7, D314, Amberlite 4200C or Amberlite 400C.

9. The integrated treatment method of scheelite according to claim 1, characterized in that, In step (3), the temperature of the back-extraction treatment or the desorption treatment is 25°C to 45°C; and / or, the concentration of the sulfuric acid is 1 mol / L to 3 mol / L.

10. The comprehensive treatment method of scheelite according to claim 1, characterized in that, The purity of the ammonium paratungstate ≥ 88.5%; and / or, the purity of calcium sulfate in the calcium product ≥ 95%.

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