Method for preparing calcium sulfate hemihydrate whiskers from tungsten smelting calcium-containing high-acid waste liquid in one step

Abstract

The invention relates to a method for preparing calcium sulfate hemihydrate whiskers from tungsten smelting calcium-containing high-acid waste liquid in one step. The preparation method comprises the following steps: weighing a proper amount of the crystal form regulating agent, dissolving the crystal form regulating agent in the calcium-containing high-acid waste liquid, heating the calcium-containing high-acid waste liquid in a water bath to a set temperature, adding diluted sulfuric acid into the calcium-containing high-acid waste liquid in the water bath, simultaneously starting stirring, quickly filtering and washing after reacting for a certain time to obtain a precipitate, and drying the precipitate to obtain the calcium-containing high-acid waste liquid. And drying the obtained precipitate to obtain the calcium sulfate hemihydrate whisker. The high-value calcium sulfate hemihydrate crystal whisker product can be prepared from the calcium-containing high-acid waste liquid through the crystal form regulating agent and a one-step method for reasonably controlling reaction conditions, and meanwhile, the obtained regenerated hydrochloric acid can be returned to a decomposition procedure for recycling.

Description

Technical Field

[0001] The invention relates to the fields of nonferrous metal metallurgy, resource recycling and inorganic material technology, and in particular to a method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid in tungsten smelting in one step. Background Art

[0002] Tungsten has excellent physical and chemical properties and is widely used in civil, industrial, military and other fields. The main mineral raw materials for the production of tungsten are wolframite and scheelite. With the increasing depletion of wolframite resources, scheelite concentrate has become the main mineral raw material for the production of tungsten. 2 CO 3 Pressure cooking and NaOH pressure cooking are the mainstream processes for recovering tungsten from scheelite. 2 CO 3 / NaOH and CaWO 4 The reaction equilibrium constant is small, and efficient decomposition of scheelite requires a large amount of Na 2 CO 3 or NaOH, resulting in higher production costs. In order to reduce costs, the prior art proposes the use of HCl-H 2 SO 4 A new process for the synergistic decomposition of scheelite was developed and applied industrially.

[0003] Using HCl-H 2 SO 4 The synergistic decomposition of scheelite will produce a large amount of calcium-containing high-acid waste liquid. In order to achieve acid recovery of this calcium-containing high-acid waste liquid, it is necessary to add H 2 SO 4 Calcium precipitation obtains calcium sulfate dihydrate slag, and the acid leaching liquid after decalcification is circulated for decomposing scheelite for recycling, which will result in the generation of a large amount of calcium sulfate dihydrate slag solid waste. Therefore, how to remove calcium from the high calcium acid waste liquid and recycle it, and at the same time, how to make use of the produced calcium sulfate dihydrate as a resource has become a research problem. The calcium sulfate dihydrate slag obtained by analysis has a low impurity content, which is mainly calcium sulfate dihydrate. If calcium sulfate dihydrate can be prepared into calcium sulfate whiskers with higher value, the problem will be solved. Calcium sulfate whiskers have excellent physical and chemical properties such as high strength, high modulus, high toughness, high insulation, high temperature resistance, acid and alkali resistance, etc., and are widely used in papermaking, coatings, rubber, plastics, etc. It is an inorganic salt whisker material with high cost performance, wide application field and great development prospects.

[0004] Chinese patent CN108950674B discloses a method for preparing semi-hydrated and anhydrous calcium sulfate whiskers in one step by a hydrothermal method. The calcium nitrate solution, calcium chloride solution or mixed solution of calcium nitrate and calcium chloride produced in the smelting industry and electroplating process is used as raw material, sulfuric acid is used as a calcium ion precipitant, and by controlling the reaction conditions, semi-hydrated and anhydrous calcium sulfate whiskers are prepared in one step, and nitric acid solution, hydrochloric acid solution or mixed solution of nitric acid and hydrochloric acid are simultaneously produced, and returned to the aforementioned smelting or electroplating process. The calcium ion concentration in the calcium-containing solution that can be treated by this method is 5-25g / L, 40-60g / L, and the hydrothermal temperature is relatively high at 125-200℃.

[0005] The prior art discloses a method for preparing calcium sulfate hemihydrate whiskers with a high aspect ratio. Soluble inorganic calcium salt and inorganic sulfate are used as raw materials, first coprecipitated at 10-90°C, filtered and washed, activated at 40-150°C for 1-6h to obtain a precursor, the precursor is added to a hydrothermal medium with a crystal form control agent, hydrothermally insulated at 80-180°C for 2-10h, washed, filtered, and dried to obtain calcium sulfate hemihydrate whiskers with an aspect ratio of 50-1000, regular morphology, and uniform size. This method has many steps and a long process flow.

[0006] Although these methods can prepare calcium sulfate or hemihydrate calcium sulfate whiskers from calcium-containing solutions to a certain extent, they either have high hydrothermal temperatures, a narrow range of calcium ion concentrations, or long process flows, and are not suitable for treating calcium-containing high-acid wastewater from tungsten smelting.

[0007] In summary, the present application now proposes a method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step to solve the above-mentioned problems. Summary of the invention

[0008] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a method for preparing hemihydrate calcium sulfate whiskers from high calcium acid waste liquid in tungsten smelting in one step.

[0009] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0010] A method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step comprises the following steps:

[0011] S1, weighing an appropriate amount of crystal form regulator and dissolving it in the calcium-containing high-acid waste liquid, heating the calcium-containing high-acid waste liquid in a water bath to a set temperature, adding diluted sulfuric acid to the calcium-containing high-acid waste liquid in the water bath, and stirring at the same time, after reacting for a certain period of time, quickly filtering and washing to obtain a precipitate;

[0012] S2. Drying the precipitate obtained in step S1 to obtain calcium sulfate hemihydrate whiskers.

[0013] As a preferred embodiment of the method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step, in the step S1, the calcium ion concentration of the calcium-containing high-acid waste liquid is ≥60g / L, and the acid concentration is 1-7mol / L.

[0014] As a preferred embodiment of the method for preparing calcium sulfate hemihydrate whiskers from tungsten smelting calcium-containing high-acid waste liquid in one step according to the present invention, wherein: in step S1, the ratio of the amount of sulfuric acid added to the number of moles of calcium ions is 0.8:1 to 1.2:1.

[0015] As a preferred embodiment of the method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid of tungsten smelting in one step according to the present invention, wherein: in the step S1, the water bath temperature is 80-100°C.

[0016] As a preferred embodiment of the method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step according to the present invention, wherein: in the step S1, the crystal form regulator is a combination of one or more of hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, sodium oleate, and sodium citrate, and the dosage is 0.5 to 50 g / L.

[0017] As a preferred embodiment of the method for preparing calcium sulfate hemihydrate whiskers from tungsten smelting calcium-containing high-acid waste liquid in one step according to the present invention, wherein: in the step S1, the stirring speed is 50-400 r / min.

[0018] As a preferred embodiment of the method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step according to the present invention, wherein: in the step S1, the reaction time is 0.5 to 3 hours.

[0019] As a preferred embodiment of the method for preparing calcium sulfate hemihydrate whiskers from tungsten smelting calcium-containing high-acid waste liquid in one step according to the present invention, wherein: in the step S2, the drying temperature is 80-100°C.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The present invention can process raw materials containing a wide range of acid and calcium ion concentrations, does not require the preparation of precursors, and can prepare hemihydrate calcium sulfate whiskers in one step;

[0022] 2. The hydrothermal temperature of the present invention is lower than 100° C., the equipment is simple, and it is easy to industrialize production to obtain high-value hemihydrate calcium sulfate whisker products. At the same time, the regenerated hydrochloric acid obtained can be recycled for the decomposition process of scheelite. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0024] Figure 1 It is a process flow chart of the present invention.

[0025] Figure 2 This is a SEM image of the calcium sulfate hemihydrate whisker prepared in Example 1 of the present invention.

[0026] Figure 3 This is a SEM image of the calcium sulfate hemihydrate whiskers prepared in Example 2 of the present invention.

[0027] Figure 4 This is a SEM image of the calcium sulfate hemihydrate whiskers prepared in Example 3 of the present invention.

[0028] Figure 5 This is a SEM image of the calcium sulfate hemihydrate whiskers prepared in Example 4 of the present invention.

[0029] Figure 6 This is a SEM image of the calcium sulfate hemihydrate whiskers prepared in Example 5 of the present invention.

[0030] Figure 7 This is a SEM image of the calcium sulfate hemihydrate whiskers prepared in Example 6 of the present invention.

[0031] Figure 8 XRD patterns of whisker products prepared in different embodiments of the present invention.

[0032] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0033] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] According to one aspect of the present invention, the present invention provides the following technical solution:

[0035] A method for preparing calcium sulfate hemihydrate whiskers from tungsten smelting calcium-containing high-acid waste liquid in one step, comprising the following steps:

[0036] S1, weighing an appropriate amount of crystal form regulator and dissolving it in the calcium-containing high-acid waste liquid, heating the calcium-containing high-acid waste liquid in a water bath to a set temperature, adding diluted sulfuric acid to the calcium-containing high-acid waste liquid in the water bath, and stirring at the same time, after reacting for a certain period of time, quickly filtering and washing to obtain a precipitate;

[0037] S2. Drying the precipitate obtained in step S1 to obtain calcium sulfate hemihydrate whiskers.

[0038] See also Figure 1 The present invention uses the calcium-containing high-acid waste liquid obtained by decomposing scheelite with hydrochloric acid in the tungsten smelting process as raw material, sulfate ions as precipitants, and appropriate crystal form regulators. By controlling the reaction conditions, hemihydrate calcium sulfate whiskers are prepared in one step, and the produced hydrochloric acid solution can be returned to the hydrochloric acid decomposition process of scheelite.

[0039] The present invention utilizes sulfuric acid to combine with calcium ions to generate calcium sulfate dihydrate. Usually, calcium sulfate dihydrate is dehydrated and converted into calcium sulfate hemihydrate or anhydrous calcium sulfate under high temperature conditions (125-200° C.). When the temperature is lower than 100° C., calcium sulfate hemihydrate cannot be prepared. However, due to the presence of a large amount of HCl in the solution, the activity of water in the system is reduced, thereby promoting the phase transformation of calcium sulfate dihydrate into calcium sulfate hemihydrate at a temperature lower than 100° C.

[0040] Preferably, in step S1, the calcium ion concentration of the calcium-containing high-acid waste liquid is ≥60 g / L, and the acid concentration is 1 to 7 mol / L. Specifically, the calcium ion concentration can be, for example, any one of 60 g / L, 100 g / L, 125 g / L, 150 g / L, 160 g / L, 175 g / L, 190 g / L, 200 g / L, or a range between any two thereof, and the acid concentration can be, for example, any one of 1 mol / L, 1.5 mol / L, 2 mol / L, 4 mol / L, 5 mol / L, 5.5 mol / L, 6.5 mol / L, or 7 mol / L, or a range between any two thereof.

[0041] Preferably, in step S1, the ratio of the amount of sulfuric acid added to the molar number of calcium ions is 0.8:1 to 1.2:1. Specifically, the amount of sulfuric acid added can be any one of 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, or a range between any two of them. Preferably, in step S1, the water bath temperature is 80 to 100°C. Specifically, the water bath temperature can be any one of 80°C, 85°C, 90°C, 95°C, 98°C, 100°C, or a range between any two of them.

[0042] The invention can prepare hemihydrate calcium sulfate whiskers at a temperature lower than 100° C. and normal pressure. Compared with the prior art in which the hydrothermal temperature is higher than 125° C., the invention does not generate steam pressure, brings convenience to the addition and operation of raw materials, and is easy for industrial production.

[0043] Preferably, in step S1, the crystal form regulator is a combination of one or more of hexadecyltrimethylammonium bromide, sodium dodecylsulfonate, sodium oleate, and sodium citrate, and the amount used is 0.5 to 50 g / L. Specifically, the amount of the crystal form regulator can be, for example, any one of 0.5 g / L, 1.5 g / L, 2.5 g / L, 3 g / L, 5 g / L, 10 g / L, 25 g / L, and 50 g / L, or the range between any two.

[0044] Preferably, in step S1, the stirring speed is 50 to 400 r / min. Specifically, the stirring speed may be, for example, any one of 50 r / min, 100 r / min, 150 r / min, 200 r / min, 250 r / min, 350 r / min, 400 r / min, or a range between any two thereof.

[0045] Preferably, in step S1, the reaction time is 0.5 to 3 hours. Specifically, the reaction time can be, for example, any one of 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, or any range between two thereof.

[0046] Preferably, in step S2, the drying temperature is 80-100° C. Specifically, the drying temperature may be, for example, any one of 80° C., 85° C., 90° C., 95° C., 100° C., or a range between any two thereof.

[0047] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0048] The calcium-containing high-acid waste liquid produced by tungsten smelting is used as raw material, and its composition is shown in Table 1:

[0049] Table 1 Composition analysis results of calcium-containing high-acid wastewater (g / L)

[0050]

[0051] Example 1

[0052] A method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step, specifically comprising: measuring 100 mL of calcium-containing high-acid waste liquid and pouring it into a conical flask, weighing 2.5 g of hexadecyltrimethylammonium bromide (CTAB), adding it to the conical flask and stirring to dissolve it, measuring the corresponding amount of concentrated sulfuric acid according to the ratio of sulfuric acid addition to the molar number of calcium ions of 1.2:1, diluting it according to the volume ratio of concentrated sulfuric acid to water of 1:1, putting the conical flask into a water bath, heating and stirring, and setting the hydrothermal temperature of 98°C and the speed of 150r / min, after the water bath temperature reaches the set value, slowly adding the diluted sulfuric acid solution into the conical flask, keeping the temperature for reaction for 2 hours, filtering it, quickly washing it with boiling water, and then putting it into a 90°C oven to bake to constant weight to obtain calcium sulfate hemihydrate whiskers.

[0053] Example 2

[0054] A method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step, specifically comprising: measuring 100 mL of high-calcium acid waste liquid and pouring it into a conical flask, weighing 3.5 g of hexadecyltrimethylammonium bromide (CTAB), adding it to the conical flask and stirring to dissolve it, measuring a corresponding amount of concentrated sulfuric acid according to a ratio of sulfuric acid addition to calcium ion molar number of 0.8:1, and diluting it according to a volume ratio of concentrated sulfuric acid to water of 1:1, placing the conical flask in a water bath, heating and stirring, and setting the hydrothermal temperature to 92°C and the rotation speed to 150 r / min, after the water bath temperature reaches the set value, slowly adding the diluted sulfuric acid solution into the conical flask, keeping the temperature for reaction for 2 hours, filtering it, quickly washing it with boiling water, and then placing it in a 90°C oven to bake to constant weight to obtain calcium sulfate hemihydrate whiskers.

[0055] Example 3

[0056] A method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step, specifically comprising: measuring 100 mL of high-calcium acid waste liquid and pouring it into a conical flask, weighing 3.5 g of hexadecyltrimethylammonium bromide (CTAB), adding it to the conical flask and stirring to dissolve, measuring a corresponding amount of concentrated sulfuric acid according to a ratio of sulfuric acid addition to the molar number of calcium ions of 1:1, and diluting it according to a volume ratio of concentrated sulfuric acid to water of 1:1, placing the conical flask in a water bath, heating and stirring, and setting the hydrothermal temperature to 98°C and the rotation speed to 150 r / min, after the water bath temperature reaches the set value, slowly adding the diluted sulfuric acid solution into the conical flask, keeping the temperature for reaction for 2 hours, filtering it, quickly washing it with boiling water, and then placing it in a 90°C oven to bake to constant weight to obtain calcium sulfate hemihydrate whiskers.

[0057] Example 4

[0058] A method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step, specifically comprising: measuring 100 mL of high-acid high-calcium waste liquid and pouring it into a conical flask, weighing 3.5 g of hexadecyltrimethylammonium bromide (CTAB), adding it to the conical flask and stirring to dissolve, measuring a corresponding amount of concentrated sulfuric acid according to a ratio of sulfuric acid addition to calcium ion molar number of 1.2:1, and diluting it according to a volume ratio of concentrated sulfuric acid to water of 1:1, placing the conical flask in a water bath, heating and stirring, and setting the hydrothermal temperature to 98°C and the rotation speed to 150 r / min, after the water bath temperature reaches the set value, slowly adding the diluted sulfuric acid solution into the conical flask, keeping the temperature for reaction for 0.5 h, filtering it, quickly washing it with boiling water, and then placing it in a 90°C oven to bake to constant weight to obtain calcium sulfate hemihydrate whiskers.

[0059] Example 5

[0060] A method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step, specifically comprising: measuring 100 mL of high-acid high-calcium waste liquid and pouring it into a conical flask, weighing 3 g of hexadecyltrimethylammonium bromide (CTAB), adding it to the conical flask and stirring to dissolve, measuring a corresponding amount of concentrated sulfuric acid according to a ratio of sulfuric acid addition to calcium ion molar number of 1.2:1, and diluting it according to a volume ratio of concentrated sulfuric acid to water of 1:1, placing the conical flask in a water bath, heating and stirring, and setting a hydrothermal temperature of 98°C and a rotation speed of 200 r / min, after the water bath temperature reaches the set value, slowly adding the diluted sulfuric acid solution into the conical flask, keeping the temperature for reaction for 2 hours, filtering it, quickly washing it with boiling water, and then placing it in a 90°C oven to bake to constant weight to obtain calcium sulfate hemihydrate whiskers.

[0061] Example 6

[0062] Table 2 Component analysis results of calcium-containing high-acid wastewater

[0063]

[0064] A method for preparing calcium sulfate hemihydrate whiskers from tungsten smelting calcium-containing high-acid waste liquid in one step, specifically comprising: taking tungsten smelting waste water with a calcium ion concentration of 60 g / L and an acid concentration of 1.92 mol / L in Table 2 as a raw material, measuring 100 mL of the waste liquid and pouring it into a conical flask, measuring a corresponding amount of concentrated sulfuric acid according to a ratio of sulfuric acid addition to the molar number of calcium ions of 1.2:1, and diluting it according to a volume ratio of concentrated sulfuric acid to water of 1:1, placing the conical flask in a water bath, heating and stirring, and setting a hydrothermal temperature of 98°C and a rotation speed of 200 r / min, after the water bath temperature reaches the set value, slowly adding the diluted sulfuric acid solution into the conical flask, keeping the temperature for reaction for 2 hours, filtering, quickly washing with boiling water, and then placing it in a 90°C oven to dry to constant weight, to obtain calcium sulfate hemihydrate whiskers.

[0065] Comparative Example 1

[0066] Taking tungsten smelting wastewater with a calcium ion concentration of 149.6 g / L and an acid concentration of 5.52 mol / L in Table 1 as raw material, 100 mL of calcium-containing high-acid waste liquid was measured and poured into a conical flask, 3 g of hexadecyltrimethylammonium bromide (CTAB) was weighed and added to the conical flask and stirred to dissolve, and the corresponding amount of concentrated sulfuric acid was measured according to the ratio of sulfuric acid addition to the molar number of calcium ions of 2:1, and diluted according to the volume ratio of concentrated sulfuric acid to water of 1:1, the conical flask was placed in a water bath for heating and stirring, and the hydrothermal temperature was set to 98°C and the speed was set to 200 r / min. After the water bath temperature reached the set value, the diluted sulfuric acid solution was slowly added to the conical flask, and after the reaction was kept warm for 2 hours, it was filtered and quickly washed with boiling water, and then placed in a 90°C oven to be dried to constant weight. The product did not obtain hemihydrate calcium sulfate whiskers, but anhydrous calcium sulfate.

[0067] Comparative Example 2

[0068] Taking tungsten smelting wastewater with a calcium ion concentration of 149.6 g / L and an acid concentration of 5.52 mol / L in Table 1 as raw material, 100 mL of calcium-containing high-acid waste liquid was measured and poured into a conical flask, 3 g of hexadecyltrimethylammonium bromide (CTAB) was weighed and added to the conical flask and stirred to dissolve, and the corresponding amount of concentrated sulfuric acid was measured according to the ratio of sulfuric acid addition to the molar number of calcium ions of 1.6:1, and diluted according to the volume ratio of concentrated sulfuric acid to water of 1:1, the conical flask was placed in a water bath for heating and stirring, and the hydrothermal temperature was set to 98°C and the speed was set to 200 r / min. After the water bath temperature reached the set value, the diluted sulfuric acid solution was slowly added to the conical flask, and after the reaction was kept warm for 2 hours, it was filtered and quickly washed with boiling water, and then placed in a 90°C oven to be dried to constant weight. The product did not obtain hemihydrate calcium sulfate whiskers, but anhydrous calcium sulfate.

[0069] See also Figure 2 to Figure 7 , which is the SEM image of the calcium sulfate hemihydrate whiskers prepared in Examples 1 to 6 of the present invention, the prepared products are needle-shaped, fibrous single crystals with uniform cross-section, complete appearance, and perfect internal structure.

[0070] Figure 8 1-3 and 1-2 are XRD diagrams of whisker products under different sulfuric acid dosages. It can be seen that calcium sulfate hemihydrate whiskers are obtained in Example 1-3, and anhydrous calcium sulfate is obtained in Comparative Example 1-2.

[0071] It can be seen from the above embodiments and comparative examples that the present invention uses the calcium-containing high-acid waste liquid obtained by hydrochloric acid decomposition of scheelite in the tungsten smelting process as a raw material, sulfate ions as a precipitant, and an appropriate crystal form regulator. By reasonably controlling the reaction conditions, a high-value calcium sulfate hemihydrate whisker product is prepared in one step, and the produced hydrochloric acid solution can be returned to the hydrochloric acid decomposition process of scheelite for recycling. The present invention utilizes sulfuric acid to combine with calcium ions to generate calcium sulfate dihydrate. Due to the presence of a large amount of HCl in the high-calcium acid waste liquid solution, the relative activity of water in the system is reduced, thereby prompting calcium sulfate dihydrate to achieve phase transformation into calcium sulfate hemihydrate at a temperature below 100°C.

[0072] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step, characterized in that: The steps include: S1, weighing an appropriate amount of crystal form regulator and dissolving it in the calcium-containing high-acid waste liquid, heating the calcium-containing high-acid waste liquid in a water bath to a set temperature, adding diluted sulfuric acid to the calcium-containing high-acid waste liquid in the water bath, and stirring at the same time, after reacting for a certain period of time, quickly filtering and washing to obtain a precipitate; S2. Drying the precipitate obtained in step S1 to obtain calcium sulfate hemihydrate whiskers.

2. The method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step according to claim 1, characterized in that: In step S1, the calcium ion concentration of the calcium-containing high-acid waste liquid is ≥60 g / L, and the acid concentration is 1-7 mol / L.

3. The method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step according to claim 2, characterized in that: In the step S1, the ratio of the amount of sulfuric acid added to the molar number of calcium ions is 0.5:1 to 1.2:

1.

4. The method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step according to claim 2, characterized in that: In the step S1, the water bath temperature is 80-100°C.

5. The method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step according to claim 1, characterized in that: In the step S1, the crystal form regulator is a combination of one or more of hexadecyltrimethylammonium bromide, sodium dodecylsulfonate, sodium oleate, and sodium citrate, and the amount used is 0.5 to 50 g / L.

6. The method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step according to claim 1, characterized in that: In the step S1, the stirring speed is 50-400 r / min.

7. The method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step according to claim 1, characterized in that: In the step S1, the reaction time is 0.5 to 3 hours.

8. The method for preparing calcium sulfate hemihydrate whiskers from calcium-containing high-acid waste liquid from tungsten smelting in one step according to claim 1, characterized in that: In step S2, the drying temperature is 80-100°C.

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