阅读说明：本技术 一种白钨矿的联合浸出剂及其处理方法 (Combined leaching agent for scheelite and treatment method thereof ) 是由 李江涛 赵中伟 陈星宇 刘旭恒 何利华 于 2019-10-14 设计创作，主要内容包括：本发明属于矿物冶炼技术领域,具体公开了一种白钨矿的联合浸出剂,为含有磷源和具有式1结构有机化合物的溶液；<Image he="114" wi="276" file="DDA0002232980330000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>本发明还提供了一种利用所述的联合浸出剂处理白钨矿的方法。本发明创新地提供了有机-无机浸出剂,通过所述的式1有机化合物与白钨矿中的钙和无机的磷源与白钨矿中的钨相互作用,可以有效保证钨的提取效果,本发明所述的联合浸出剂可以有效避免现有无机浸出剂存在的腐蚀、挥发、钙盐沉淀率不高等问题,此外,还有利于浸出液的钨的提纯。(The invention belongs to the technical field of mineral smelting, and particularly discloses a combined leaching agent for scheelite, which is a solution containing a phosphorus source and an organic compound with a structure shown in a formula 1; The invention also provides a method for treating scheelite by using the combined leaching agent. The invention innovatively provides an organic-inorganic leaching agent, and the organic compound shown in the formula 1 interacts with calcium and an inorganic phosphorus source in scheelite and tungsten in the scheelite, so that the organic-inorganic leaching agent can effectively protect the scheeliteaccording to the tungsten extraction effect, the combined leaching agent provided by the invention can effectively avoid the problems of corrosion, volatilization, low calcium salt precipitation rate and the like of the existing inorganic leaching agent, and is beneficial to purification of tungsten of the leaching solution.)

1. The combined leaching agent of scheelite is characterized by being a solution containing a phosphorus source and an organic compound with a structure shown in a formula 1;

2. the combined leaching agent for scheelite according to claim 1, wherein the phosphorus source is at least one of phosphoric acid or phosphorite.

3. The combined leaching agent for scheelite according to claim 2, wherein the molar ratio of the phosphorus in the phosphorus source to the elements of tungsten in the scheelite to be treated is 1:12 to 1: 2.

4. The combined leaching agent for scheelite according to any one of claims 1 to 3, wherein the molar concentration of the organic compound having the structure of formula 1 in the combined leaching agent is 0.5 to 3.0 mol/L.

5. a method for the treatment of scheelite, characterized in that leaching is carried out using a combined leaching agent according to any one of claims 1 to 4, obtaining a leachate enriched with calcium and tungsten.

6. the scheelite treatment method according to claim 5, wherein the temperature of the leaching process is 40 to 90 ℃;

The leaching time is preferably 0.5-4 h;

The liquid-solid ratio in the leaching process is preferably 5: 1-15: 1;

Preferably, the grade of the scheelite is WO₃10-70% and the particle size is less than or equal to 150 μm;

Preferably, the grade of associated wolframite in the scheelite is less than or equal to 5%, and the mass fraction of iron is less than or equal to 3%.

7. The method according to claim 5 or 6, wherein the tungsten in the leachate is extracted by extraction or ion exchange; collecting to obtain tungsten extract and calcium-containing extract mother liquor; wherein, the solution obtained by back extraction of the tungsten-loaded organic phase obtained by the extraction method is a tungsten extracting solution, and the raffinate is an extraction mother liquor containing calcium;

Ion exchange method to obtain ion exchange resin loaded with tungsten and exchanged liquid containing calcium ion; the desorption solution of the ion exchange resin loaded with tungsten is tungsten extracting solution; the exchanged liquid is the extraction mother liquor containing calcium;

The extraction steps are as follows: adopting primary amine extractant N₁₉₂₃Composition and body of organic phase for extraction

N with volume ratio of 10-20%₁₉₂₃20 percent of secondary octanol and 60 to 70 percent of kerosene; the O/A ratio is 1: 0.5-1: 3;

The ion exchange step comprises the following steps: extracting tungsten in the leachate by adopting macroporous weakly basic anion exchange resin D301, wherein the volume ratio of the resin to the leachate is 0.2: 1-2: 1.

8. The scheelite treating method according to claim 7, wherein the loaded tungsten organic phase obtained by the solvent extraction method is back-extracted by using 3-7mol/L ammonia water, and the ratio is 1: 1-3: 1;

desorbing the loaded tungsten ion exchange resin obtained by the ion exchange method by using 3-7mol/L ammonia water, wherein the volume ratio of the loaded tungsten ion exchange resin to the ammonia water is 1: 1-5: 1.

9. The scheelite treatment method according to any one of claims 5 to 8, wherein the extraction mother liquor is subjected to a sulfuric acid decalcification treatment to obtain calcium sulfate;

In the process of decalcification of sulfuric acid: the molar ratio of the use amount of the sulfuric acid to the content of calcium in the extraction mother liquor is 0.9: 1-0.99: 1, the reaction temperature is 20-90 ℃, and the reaction time is 0.2-4 hours;

in the process of decalcification of sulfuric acid: seed crystals of at least one of dihydrate gypsum, semi-hydrated gypsum and anhydrous gypsum are added, and the addition amount of the seed crystals in 1L of extraction mother liquor is 0.5-5 g.

10. The method of treating scheelite according to claim 9, wherein the solution after decalcification of sulfuric acid is recycled to the leaching step.

Technical Field

The invention relates to a tungsten extraction process in the field of hydrometallurgy, in particular to a scheelite treatment method.

Background

the tungsten industry is the dominant industry in China, the world first of tungsten resource reserves in China, and the first of output and export.

At present, one of the mainstream processes in China still uses the processing technology of scheelite NaOH autoclaving to process scheelite. The process effectively decomposes scheelite under the strengthening conditions of high alkali concentration, high temperature and high pressure, and the slag contains WO₃Can be reduced to 1-3%. However, with the increasing strictness of the national environmental protection policy, the tungsten smelting production mode with high energy consumption and high alkali consumption will face more severe environmental protection pressure. The low-grade scheelite can be stably decomposed by adopting a soda-pressure boiling method for treating scheelite abroad, the tungsten content in slag is generally lower than 0.5 percent, but the dosage of reagents is too large and generally reaches 3 times of theoretical quantity, and laboratory studies in China even 5-6 times are needed. The operation temperature is as high as about 225 ℃, and the equipment pressure reaches 20 atm.

hydrochloric acid has also been used in the past to decompose scheelite concentrates, which have a high tendency to react thermodynamically. However, when hydrochloric acid is decomposed, tungstic acid is yellow colloid and wraps the surface of undecomposed scheelite, incomplete decomposition is easily caused, the problems of acid corrosion and volatilization of hydrochloric acid are serious, the working environment is severe, and finally a large amount of residual hydrochloric acid mother liquor is neutralized into CaCl by lime₂The solution is discharged and is basically abandoned at present. The tungsten can form soluble heteropoly acid (such as [ PW ] with the hetero-tungsten ratio of 1: 6-1: 12 with impurities such as phosphorus, arsenic, silicon and the like₁₂O₄₀]^3-) And a small amount of phosphorus can cause dispersion and loss of a large amount of tungsten in the hydrochloric acid decomposition process, so that the hydrochloric acid decomposition process mainly treats high-grade scheelite concentrate (low impurities such as phosphorus, arsenic and the like are required). However, a small amount of phosphoric acid is intentionally added during leaching to make tungsten into solution, so as to solve the problem that tungstic acid is wrapped to influence decomposition during hydrochloric acid decomposition (ZL201310414618.8), the corrosion and volatilization problems of hydrochloric acid are still a headache. In addition, due to Cl^-the complexing action of (A) promotes the impurity Fe in the mineral to be Fe (Cl)^-)₆]^3-、[Fe(Cl^-)₄]^2-The anion form leaching is carried out, the tungsten which is the complex anion is extracted together with the anion in the subsequent process (such as extracting tungsten by an ion exchange method or a solvent extraction method), and if ammonia water is adopted for carrying out back extraction and transformation to be ammonium tungstate solution, the hydroxide precipitation of iron can occur, so that the separation difficulty is increased. Research reports that a method for leaching scheelite by using nitric acid and phosphoric acid in a complexing manner (ZL201310218994.X) is adopted, but the nitric acid is also easy to volatilize, the nitric acid is easy to react with an organic flotation reagent in the scheelite to generate nitrogen dioxide harmful gas when the scheelite is decomposed, and a leachate contains high-concentration nitric acid, so that the leachate has strong oxidizing property and has a great destructive effect on an extractant or ion exchange resin in subsequent tungsten extraction. In addition, because the solubility of calcium nitrate in the nitric acid-phosphoric acid leaching solution is very high, when sulfuric acid is added into the mother liquor after tungsten extraction to regenerate nitric acid, the precipitation rate of calcium sulfate is not high. The literature (Zhengxian, research on the crystal form and solubility of calcium sulfate in nitric acid-phosphoric acid medium, Master academic thesis, 2010, university of Tai principle engineering) reports that calcium sulfate has a certain solubility in nitric acid-sulfuric acid system, and the precipitation rate of calcium sulfate decreases greatly with increasing nitric acid concentration, for example, the crystallization rate of calcium sulfate is only 75.22% at 20% nitric acid concentration.

In order to overcome the problem of a hydrochloric acid or nitric acid complexing system in the method, the existing improved method adopts sulfuric acid-phosphoric acid as a leaching agent. However, when a large amount of sulfuric acid exists, the supersaturation degree of the solution to calcium sulfate is extremely high, which often leads to rapid nucleation of gypsum to form a large amount of fine crystals to cause coating, and thus the decomposition effect is not ideal. Therefore, patents ZL 201010605095.1, ZL201010605107.0, ZL 201410704909.5, ZL 201410706456.X, ZL201410705800.3 and the like provide a method for synergistic leaching of scheelite by sulfur and phosphorus mixed acid, the supersaturation degree of calcium sulfate in a solution during decomposition is reduced by improving the concentration of phosphoric acid, a dihydrate gypsum seed crystal is added to promote heterogeneous nucleation, measures such as homogeneous nucleation and the like are inhibited, and the problem of wrapping of a calcium sulfate solid film can be effectively solved by changing a feeding mode and designing special decomposition equipment to control crystallization of calcium sulfate. Further, gypsum, which is a decomposition product, contains impurities such as refractory gangue that do not react with the system, and is therefore generally used only as a base material for building materials. The industrial byproduct gypsum has low additional value, so researchers develop researches on preparing gypsum whiskers with high additional value by dissolving the byproduct gypsum.

The existing leaching agent of scheelite is an inorganic leaching agent, and can obtain a better leaching effect, but still has the defects of corrosivity, easy volatilization, poor working condition, high environmental protection pressure, low calcium salt precipitation rate and the like.

Disclosure of Invention

In order to solve the problems in the prior art, a first object of the present invention is to provide an organic-inorganic synergistic scheelite leaching agent, which aims to reduce the impurity co-extraction phenomenon in the tungsten extraction process of the leaching solution on the premise of realizing high recovery of tungsten and calcium.

The second purpose of the invention is to provide a scheelite treatment method, which can realize the atmospheric efficient leaching of the scheelite; the leaching agent can be recycled, so that the leaching cost and the wastewater discharge are greatly reduced, and in addition, the tungsten can be effectively purified.

A combined leaching agent of scheelite is a solution containing a phosphorus source and an organic compound with a structure shown in a formula 1;

The invention innovatively provides an organic-inorganic leaching agent, the extraction effect of tungsten can be effectively ensured through the interaction of the organic compound shown in the formula 1, calcium in scheelite, an inorganic phosphorus source and tungsten in scheelite, the combined leaching agent can effectively avoid the problems of corrosion, volatilization, low calcium salt precipitation rate and the like of the existing inorganic leaching agent, and in addition, the tungsten purification of the leaching solution is facilitated.

The combined leaching agent provided by the invention can effectively realize high-efficiency leaching of tungsten by means of interaction between S-O bonds of the organic compound with the structure shown in the formula 1, S ═ O and scheelite metal and the action of the phosphorus source, avoids the problem of film solidification in the leaching process, effectively improves the leaching rate of tungsten, and is beneficial to purification of tungsten and precipitation and recovery of calcium.

the combined leaching agent is an aqueous solution in which a phosphorus source and an organic compound with a structure shown in a formula 1 are dissolved. In the solution, the phosphorus source is at least one of phosphoric acid and phosphorite.

The element molar ratio of phosphorus in the phosphorus source to tungsten in the scheelite to be treated is 1: 12-1: 2.

Preferably, the molar concentration of the organic compound with the structure shown in the formula 1 in the combined leaching agent is 0.5-3.0 mol/L.

The invention also provides a method for treating scheelite, which utilizes the combined leaching agent to leach to obtain leachate enriched with calcium and tungsten.

The organic-inorganic synergistic leaching agent is innovatively used, the element leaching behavior of the scheelite can be regulated and controlled, and the tungsten and calcium are synchronously leached. Moreover, the existence of the compound shown in the formula 1 in the leaching solution can improve the selectivity of impurities and tungsten, and the co-extraction of the impurities is also obviously reduced on the premise of ensuring the extraction rate of the tungsten.

Preferably, the grade of the scheelite is WO₃10-70% and the particle size is less than or equal to 150 μm.

Preferably, the grade of associated wolframite in the scheelite is less than or equal to 5%, and the mass fraction of iron is less than or equal to 3%.

Preferably, the temperature of the leaching process is 40-90 ℃.

preferably, the leaching time is 0.5h to 4 h.

preferably, the liquid-solid ratio in the leaching process is 5: 1-15: 1.

preferably, the tungsten in the leaching solution is extracted by extraction or ion exchange; collecting the tungsten extract and the extraction mother liquor containing calcium. Wherein, the solution obtained by back extraction of the tungsten-loaded organic phase obtained by the extraction method is a tungsten extracting solution, and the raffinate is an extraction mother liquor containing calcium. Ion exchange method to obtain ion exchange resin loaded with tungsten and exchanged liquid containing calcium ion; the desorption solution of the ion exchange resin loaded with tungsten is tungsten extracting solution; the exchanged solution is the extraction mother liquor containing calcium.

The extraction steps are as follows: adopting primary amine extractant N₁₉₂₃The components of the organic phase for extraction and the volume ratio of N are 10 to 20 percent₁₉₂₃20 percent of secondary octanol and 60 to 70 percent of kerosene. The temperature is 20-40 ℃. The O/A ratio is 1: 0.5-1: 3. and extracting tungsten in the leaching solution after 5-15 min of mixing time.

And (3) carrying out back extraction on the tungsten-loaded organic phase obtained by the solvent extraction method by using 3-7mol/L ammonia water, wherein the ratio (O/A) is 1: 1-3: 1, the back extraction temperature is 40-60 ℃, the back extraction time is 5-20 min, and the ammonium tungstate solution is obtained after the back extraction is finished.

The ion exchange step comprises the following steps: extracting tungsten in the leachate by adopting macroporous weakly basic anion exchange resin D301, wherein the volume ratio of the resin to the solution is 0.2: 1-2: 1. the temperature is 20-40 ℃, and the stirring contact time is 0.5-2 h.

Desorbing the loaded tungsten ion exchange resin obtained by the ion exchange method by using 3-7mol/L ammonia water, wherein the volume ratio of the loaded tungsten ion exchange resin to the ammonia water is 1: 1-5: 1. and (3) desorbing at the temperature of 40-60 ℃ for 0.5-2h to obtain the ammonium tungstate solution after the desorption is finished.

Preferably, the extraction mother liquor is subjected to a sulfuric acid decalcification treatment to obtain calcium sulfate.

Preferably, in the sulfuric acid decalcification process: the molar ratio of the use amount of the sulfuric acid to the content of calcium in the extraction mother liquor is 0.9: 1-0.99: 1, the reaction temperature is 20-90 ℃, and the reaction time is 0.2-4 hours.

Preferably, in the sulfuric acid decalcification process: seed crystals of at least one of dihydrate gypsum, semi-hydrated gypsum and anhydrous gypsum are added, and the addition amount of the seed crystals in 1L of extraction mother liquor is 0.5-5 g.

Preferably, the solution after the decalcification of the sulfuric acid is recycled to the leaching step.

The invention has the advantages that:

(1) the organic-inorganic leaching agent can ensure the efficient leaching of tungsten and calcium through the interaction of the organic compound shown in the formula 1 and calcium in the scheelite, an inorganic phosphorus source and tungsten in the scheelite; in addition, on the premise of realizing high-efficiency tungsten extraction, impurity co-extraction can be effectively reduced, extraction of tungsten is facilitated, and precipitation of calcium is facilitated;

(2) The leaching process can essentially solve the problem that leaching is influenced by solid film wrapping, and the efficient leaching of the scheelite is realized;

(3) High-quality gypsum whiskers are generated in the decalcification process, so that the additional value of the product is greatly improved;

(4) The treatment equipment is simple, the operation is convenient, and the industrialization is easy to realize.

Drawings

FIG. 1 is an XRD pattern of calcium sulfate crystals obtained in example 1;

FIG. 2 is a photograph of the apparent color of the calcium sulfate crystals obtained in example 1;

Fig. 3 is an SEM image of the calcium sulfate crystals obtained in example 1.

Detailed Description

The following examples are presented to further illustrate the invention and are not intended to limit the invention further.

In the following cases, the said ratios refer to the volume ratio of the organic phase and the aqueous phase (O/A), unless otherwise stated;