阅读说明：本技术 一种利用混酸分解白钨精矿短流程高效制备氧化钨的方法 (Short-process efficient preparation method of tungsten oxide by decomposing scheelite concentrate with mixed acid ) 是由 刘庆生 程华金 钟春明 曹蒙 于 2020-08-13 设计创作，主要内容包括：一种利用混酸分解白钨精矿短流程高效制备氧化钨的方法：先用草酸和硫酸的混酸溶液将白钨精矿分解,得到以络合物(H<Sub>2</Sub>[WO<Sub>3</Sub>(C<Sub>2</Sub>O<Sub>4</Sub>)H<Sub>2</Sub>O])为主的分解液和以硫酸钙为主的分解渣,再对上一步得到的分解液进行加热处理,进一步得到以草酸为主的分解液和以钨酸为主的分解渣,最后,通过对以钨酸为主的分解渣进行煅烧处理,以制得氧化钨；本发明利用混酸对白钨精矿进行分解,可使钨的浸出率达99.0％以上,且能有效避免非挥发性磷元素等杂质的引入；此外,本发明还利用了络合物(H<Sub>2</Sub>[WO<Sub>3</Sub>(C<Sub>2</Sub>O<Sub>4</Sub>)H<Sub>2</Sub>O])受热易分解得到草酸和钨酸这一性质,简化了由白钨精矿制备氧化钨的工艺流程；并且,本发明也实现了对草酸的循环回用；综上,本发明具有经济节约,流程精短,绿色环保和高质高效的特点。(A short-process high-efficiency preparation method of tungsten oxide by decomposing scheelite concentrate with mixed acid comprises the following steps: decomposing scheelite concentrate with mixed acid solution of oxalic acid and sulfuric acid to obtain complex (H) 2 [WO 3 (C 2 O 4 )H 2 O]) Heating the decomposition liquid obtained in the last step to further obtain decomposition liquid mainly containing oxalic acid and decomposition slag mainly containing tungstic acid, and finally calcining the decomposition slag mainly containing tungstic acid to obtain tungsten oxide; according to the method, the scheelite concentrate is decomposed by using the mixed acid, so that the leaching rate of tungsten can reach more than 99.0%, and the introduction of impurities such as non-volatile phosphorus elements can be effectively avoided; in addition, the invention also utilizes a complex (H) 2 [WO 3 (C 2 O 4 )H 2 O]) The property of oxalic acid and tungstic acid which are easily decomposed by heating simplifies the process flow of preparing tungsten oxide by the white tungsten concentrate; in addition, the invention also realizes the recycling of oxalic acid; in conclusion, the method has the characteristics of economy, saving, short flow, environmental protection, high quality and high efficiency.)

1. A short-flow high-efficiency preparation method of tungsten oxide by decomposing scheelite concentrate with mixed acid is characterized by mainly comprising the following steps: (1) mixed acid decomposition: adding the scheelite concentrate powder into a mixed acid solution of oxalic acid and sulfuric acid to carry out a decomposition reaction of the scheelite concentrate;

(2) and (3) filtering: filtering the solid-liquid mixture obtained by decomposition in the step (1) to obtain calcium sulfate (CaSO)₄) Decomposed slag mainly, and complex (H)₂[WO₃(C₂O₄)H₂O]) Mainly decomposing the liquid, and then separating the decomposed liquidCollecting for later use;

(3) heating and decomposing: heating and decomposing the decomposition liquid collected in the step (2);

(4) and (3) filtering: filtering the solid-liquid mixture obtained in the step (3) through heating decomposition to respectively obtain oxalic acid H₂C₂O₄Mainly decomposed liquid, and tungstic acid (H)₂WO₄) Mainly decomposed slag;

(5) preparing tungsten oxide: and (4) calcining the decomposition slag to be used in the step (4) to prepare the tungsten oxide.

2. The method of claim 1, wherein (1) the mixed acid decomposes: according to the following steps of 1: (10-20) g/ml solid-to-liquid ratio requirement, the particle size is not more than 200 mu m, and the grade is 30-70% (by WO)₃Calculated) adding the scheelite concentrate powder into a mixed acid solution of oxalic acid and sulfuric acid to perform a decomposition reaction of the scheelite concentrate, wherein the concentration of the added oxalic acid solution is 0.5-1.5mol/L, the concentration of the sulfuric acid solution is 1.0-2.0mol/L, the reaction temperature is maintained at 20-100 ℃, and the reaction time is 1-5 hours.

3. The method of claim 1, wherein (3) pyrolysis: the heating temperature is set to be 50-100 ℃ in the heating decomposition process, the normal pressure is realized, and the heating time is 1-3 h.

4. The method of claim 1, wherein (4) filtering: the obtained oxalic acid (H)₂C₂O₄) Collecting the main decomposition liquid for reuse, washing the obtained decomposition residue, and drying for later use; wherein oxalic acid (H)₂C₂O₄) The main decomposition liquid can be recycled to the step of decomposing the mixed acid of the scheelite concentrate.

5. The method of claim 1, wherein (5) preparing a tungsten oxide: the calcining temperature is set to be 600-800 ℃, and the calcining time is 1-4 h.

6. The method according to claim 2, wherein in step (1), the solid-to-liquid ratio is preferably 1: 15g/ml, the concentration of the oxalic acid solution is preferably 1mol/L, the concentration of the sulfuric acid solution is preferably 1.5mol/L, the reaction temperature is preferably maintained at 70 ℃, and the reaction time is preferably 2.5 h.

7. The method according to claim 3, wherein in step (3), the heating temperature is preferably 85 ℃ and the heating time is preferably 2 h.

8. The method according to claim 5, characterized in that the calcination temperature is preferably 700 ℃ and the calcination time is preferably 3 h.

Technical Field

The invention belongs to the field of hydrometallurgy and extraction of metal tungsten, and particularly relates to a short-flow high-efficiency preparation method of tungsten oxide by decomposing scheelite concentrate with mixed acid.

Background

At present, 80% of scheelite mined in the world is used for smelting high-quality steel, 15% of scheelite mined in the world is used for producing hard steel, and 5% of scheelite mined in the world is used for other purposes. Tungsten can be used for manufacturing nozzles of firearms and rocket propellers and cutting metal, and is a metal with wide application. At present, the main consumed resource for tungsten smelting in China is wolframite, the basic reserve of the wolframite resource is only about 49.13 ten thousand tons, and the wolframite resource is consumed in several years, and in addition, newly discovered tungsten resources are mostly complex scheelite resources, so the situation that the scheelite occupies absolute advantages is presented. Therefore, the development of the white tungsten resource to replace the black tungsten is a strategic rule for sustainable development of the tungsten industry in China.

According to the literature, the industrial methods for processing scheelite can be roughly divided into the following three types:

firstly, an alkaline leaching process: the alkaline leaching process is based on the generation of insoluble calcium salts, which are also classified as Na₂CO₃A high pressure leaching process and a NaOH leaching process. Na (Na)₂CO₃The high-pressure leaching process is suitable for treating scheelite concentrate and scheelite and wolframite mixed middlings, is mature at present, and becomes a common method for treating scheelite at present. Na (Na)₂CO₃The high-pressure leaching process is completed in a high-pressure kettle, the reaction temperature is 190-230 ℃, the corresponding pressure is 1.2-2.6 MPa, and the high-pressure leaching process has the advantages of strong adaptability to tungsten mineral raw materials, high leaching rate (generally reaching about 99%), low leaching effect on main impurities (such As P, As and Si) and the like. However, Na is also present in the process₂CO₃An excessively high initial concentration of the leaching agent leads to an "abnormal phenomenon" in which the leaching rate is reduced, and therefore Na cannot be used in a high concentration₂CO₃The leaching agent thermodynamically and kinetically enhances the leaching process. The solution is mainly to enhance the thermodynamics and kinetics of the leaching reaction by increasing the reaction temperature, but not only increases the energy consumption, but also increases the equipment of the reaction kettleThe material and the operation safety put forward more strict requirements. The other is NaOH leaching process, and the essence of NaOH leaching scheelite is to leach WO in tungsten minerals₃Conversion to Na₂WO₄Into aqueous solution, and calcium is dissolved in Ca (OH) which is difficult to dissolve₂The slag phase is separated from the tungsten. In recent years, domestic tungsten metallurgy workers have successfully developed an alkali pressure cooking leaching process, a hot ball mill-alkali leaching process, a reaction extrusion method-alkali leaching process and the like, and can be applied to leaching of various tungsten mineral raw materials including black tungsten concentrate, white tungsten concentrate and black and white tungsten mixed middlings.

Secondly, an acid leaching process: acid leaching has been the primary method of treating standard scheelite concentrate in the traditional tungsten leaching process. The process has the advantages of short flow, low cost and the like, but has the outstanding defects that the acid waste liquid has serious pollution to the environment, and simultaneously has serious corrosion to plants and equipment, and the difficulty of further improving the product quality is high. Therefore, the main process for treating the standard white tungsten concentrate is eliminated, but certain reference value is still provided when certain special materials or certain intermediate products are treated, and the process can be used for decomposing artificial white tungsten. The scheelite acid leaching process mainly comprises a hydrochloric acid (HCl) leaching process and nitric acid (HNO)₃) And (4) leaching.

Thirdly, other processes: in addition to the above-mentioned several conventional industrial white tungsten leaching processes, other leaching methods mainly include leaching processes based on stable coordination compounds that generate calcium and on isopoly (or heteropoly) acids or heteropoly acids that generate stable tungsten in an acidic solution.

Heretofore, many researchers have conducted studies on the decomposition of scheelite with an acid, for example: in patent document 1(CN201810331443, a method for decomposing scheelite under pressure by using mixed phosphoric and sulfur acid), a method for decomposing scheelite by using mixed phosphoric and sulfur acid is mentioned, and researches show that when scheelite is treated by using mixed phosphoric and sulfur acid, the method has the advantages of high decomposition speed and high leaching rate, but inevitably brings non-volatile phosphorus element impurities and other problems in the treatment process; patent document 1(CN201610527576, a method and a system for decomposing scheelite concentrate) discloses a method for decomposing scheelite concentrate by oxalic acid, and then extracting, back-extracting, evaporating and crystallizing to obtain APT product, but experiments show that when the scheelite concentrate is decomposed by oxalic acid, the consumption of oxalic acid is high, the decomposition rate is slow, and the leaching rate is low.

At present, although there are many methods and processes for treating scheelite, these methods and processes have more or less problems, such as high energy consumption, high cost, serious pollution, etc. Therefore, in order to further utilize scheelite resources, the invention provides a new process for preparing tungsten oxide in an efficient and environment-friendly manner without introducing non-volatile impurities such as phosphorus and the like, and a short flow is ensured, so that contribution to sustainable development of tungsten industrial resources in China is hopefully made.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a short-flow high-efficiency method for preparing tungsten oxide by decomposing scheelite concentrate by using mixed acid.

A method for preparing tungsten oxide by decomposing scheelite concentrate with mixed acid mainly comprises the following steps: (1) mixed acid decomposition: adding the scheelite concentrate powder into a mixed acid solution of oxalic acid and sulfuric acid to carry out a decomposition reaction of the scheelite concentrate;

(2) and (3) filtering: filtering the solid-liquid mixture obtained by decomposition in the step (1) to obtain calcium sulfate (CaSO)₄) Decomposed slag mainly, and complex (H)₂[WO₃(C₂O₄)H₂O]) Mainly decomposing liquid, and collecting the decomposition liquid for later use;

(3) heating and decomposing: heating and decomposing the decomposition liquid collected in the step (2);

(4) and (3) filtering: filtering the solid-liquid mixture obtained in the step (3) through heating decomposition to respectively obtain oxalic acid (H)₂C₂O₄) Mainly decomposed liquid, and tungstic acid (H)₂WO₄) Mainly decomposed slag;

(5) preparing tungsten oxide: and (4) calcining the decomposition slag to be used in the step (4) to prepare the tungsten oxide.

The further concrete scheme is as follows:

(1) mixed acid decomposition: according to the following steps of 1: (10-20) the solid-to-liquid ratio of g/ml is required, the particle size is not more than 200 mu m, and the grade is 30-70% (based on WO)₃Calculated) adding the scheelite concentrate powder into a mixed acid solution of oxalic acid and sulfuric acid to carry out the decomposition reaction of the scheelite concentrate, wherein the concentration of the added oxalic acid solution is 0.5-1.5mol/L, the concentration of the sulfuric acid solution is 1.0-2.0mol/L, the reaction temperature is maintained at 20-100 ℃, and the reaction time is 1-5 hours;

(2) and (3) filtering: filtering the solid-liquid mixture obtained by decomposition in the step (1) to obtain calcium sulfate (CaSO)₄) Decomposed slag mainly, and complex (H)₂[WO₃(C₂O₄)H₂O]) Collecting the decomposition liquid as the main decomposition liquid for later use;

(3) heating and decomposing: heating and decomposing the decomposition liquid collected in the step (2), wherein the heating temperature is set to be 50-100 ℃ in the heating and decomposing process, the normal pressure is kept, and the heating time is 1-3 h;

(4) and (3) filtering: filtering the solid-liquid mixture obtained in the step (3) through heating decomposition to respectively obtain oxalic acid (H)₂C₂O₄) Mainly decomposed liquid, and tungstic acid (H)₂WO₄) Mainly decomposed slag; wherein, the obtained decomposition liquid needs to be collected for reuse, and the obtained decomposition slag is washed clean and dried for later use; with oxalic acid (H)₂C₂O₄) The main decomposition liquid can be circularly used in the step of decomposing the mixed acid of the scheelite concentrate;

(5) preparing tungsten oxide: and (4) calcining the decomposition slag to be used in the step (4) to prepare the tungsten oxide. In the calcining process for preparing the tungsten oxide, the calcining temperature is set to be 600-800 ℃, and the calcining time is 1-4 h.

Further, in the step (1), the solid-to-liquid ratio is preferably 1: 15g/ml, the concentration of the oxalic acid solution is preferably 1mol/L, the concentration of the sulfuric acid solution is preferably 1.5mol/L, the reaction temperature is preferably maintained at 70 ℃, and the reaction time is preferably 2.5 h.

Further, in the step (3), the heating temperature is preferably 85 ℃ and the heating time is preferably 2 hours.

Further, in the step (5), the calcination temperature is preferably 700 ℃ and the calcination time is preferably 3 hours.

The reaction equation for decomposing the scheelite concentrate by the mixed acid of oxalic acid and sulfuric acid is as follows:

CaWO₄+H₂C₂O₄+H₂SO₄→CaSO₄+H₂[WO₃(C₂O₄)H₂O]

by using the method for decomposing the mixed acid, the leaching rate of tungsten can reach more than 99 percent, the introduction of impurity elements such as non-volatile phosphorus and the like is effectively avoided, and the quality of tungsten oxide products is further ensured; meanwhile, the present invention utilizes complex (H)₂[WO₃(C₂O₄)H₂O]) Is easily decomposed by heating to obtain oxalic acid (H)₂C₂O₄) And tungstic acid (H)₂WO₄) This property is obtained by heating complex (H) obtained after decomposing scheelite concentrate with mixed acid₂[WO₃(C₂O₄)H₂O]) The main decomposition liquid is treated, and the reaction equation is (under heating condition):

H₂[WO₃(C₂O₄)H₂O]→H₂C₂O₄+H₂WO₄

tungstic acid (H) from which tungsten oxide can be decomposed by heating₂WO₄) Calcining to obtain the catalyst, wherein the reaction equation is as follows:

H₂WO₄→WO₃+H₂O

the whole process flow is precise and short, has high quality and high efficiency, has the characteristics of environmental protection, economy and economy, and is a method for preparing tungsten oxide with short flow and high efficiency;

the method has the following beneficial effects:

a. the method utilizes the mixed acid of oxalic acid and sulfuric acid to decompose the scheelite concentrate, so that the leaching rate of tungsten can reach more than 99 percent;

b. according to the method, the scheelite concentrate is decomposed by using the mixed acid of oxalic acid and sulfuric acid, so that the problems of introduction of impurity elements such as non-volatile phosphorus and the like are effectively avoided, and the quality of a tungsten oxide product is further ensured;

c. the invention can realize the recycling of oxalic acid, greatly reduces the consumption of oxalic acid, and is a new green, environment-friendly, economic and economical process;

d. the present invention utilizes a complex (H)₂[WO₃(C₂O₄)H₂O]) Easily decomposed into oxalic acid (H) by heating₂C₂O₄) And tungstic acid (H)₂WO₄) The property of the method ensures that the tungsten oxide prepared by the scheelite only needs to be subjected to three steps of scheelite leaching (including filtration) → complex heating decomposition (including filtration) → tungstic acid calcination to prepare the tungsten oxide, and the method is a new process with a short flow, economy and economy.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.