Use method of industrial waste sulfuric acid and calcium sulfate whisker preparation system

Abstract

The invention discloses a use method of industrial waste sulfuric acid and a calcium sulfate whisker preparation system, and solves the problem that the process of preparing calcium sulfate whiskers by using industrial waste sulfuric acid is complicated. Comprising the following steps: respectively obtaining an industrial waste sulfuric acid raw material and a calcium sulfate dihydrate powder raw material; detecting the concentration of the industrial waste sulfuric acid raw material, and taking the industrial waste sulfuric acid raw material as standby industrial waste sulfuric acid when the concentration detection value of the industrial waste sulfuric acid raw material meets a set condition; when the concentration detection value of the industrial waste sulfuric acid raw material does not meet the set condition, the concentration of the industrial waste sulfuric acid raw material is adjusted, and the industrial waste sulfuric acid raw material with the adjusted concentration meeting the set condition serves as standby industrial waste sulfuric acid; respectively adding the standby industrial waste sulfuric acid and the calcium sulfate dihydrate powder raw material into a reaction container according to a set addition amount to obtain crystallized calcium sulfate whiskers and used industrial waste sulfuric acid; and carrying out solid-liquid separation on the calcium sulfate whiskers and the used industrial waste sulfuric acid.

Description

Technical Field

[0001] The invention relates to a method for using industrial waste sulfuric acid and a system for preparing calcium sulfate whiskers. Background Art

[0002] Catalytic flue gas desulfurization technology is a desulfurization technology with great application prospects. Generally speaking, its basic principle is: sulfur dioxide, water, and oxygen in the flue gas are adsorbed on the catalyst and react to generate sulfuric acid under the catalytic action of the active components; when the sulfuric acid attached to the catalyst reaches a certain level, dilute sulfuric acid and / or water are used as regeneration liquid to circulate and spray the catalyst to remove the attached sulfuric acid and release the catalyst active sites (the above-mentioned cyclic spraying process is called catalyst regeneration); and the regeneration liquid (dilute sulfuric acid) after use is then used as a sulfuric acid by-product for subsequent utilization.

[0003] The applicant disclosed a method and device for treating sulfuric acid byproduct obtained by regenerating a desulfurization catalyst in the patent document of publication number CN109399668A, and proposed mixing the sulfuric acid byproduct obtained by regenerating a desulfurization catalyst (a kind of industrial waste sulfuric acid) with ammonia water and reacting to obtain a mixed solution containing ammonium sulfate solution and metal hydroxide precipitate, and then subjecting the mixed solution to solid-liquid separation treatment to obtain an ammonium sulfate solution and impurities containing metal hydroxides, respectively, so that the sulfuric acid byproduct obtained by regenerating a desulfurization catalyst can be converted into ammonium sulfate while the impurities such as iron and aluminum in the sulfuric acid can be effectively removed, and the obtained ammonium sulfate can be easily utilized. However, the solution of the patent document is applicable to occasions with an ammonium sulfate section, and the scope of use is limited.

[0004] The patent document with publication number CN211487179U discloses a system for flue gas desulfurization and preparation of gypsum whiskers, and proposes to use the regenerated liquid used in the catalytic flue gas desulfurization technology as a raw material for preparing gypsum whiskers to react with calcium chloride to prepare gypsum whisker products. One solution in the patent document requires the use of ammonia water as a regeneration liquid to wash the catalyst to achieve catalyst regeneration. Ammonia water is highly volatile and easily causes secondary environmental pollution; another solution in the patent document uses sulfuric acid solution as a regeneration liquid to wash the catalyst to achieve catalyst regeneration. The regeneration liquid needs to react with ammonia water to generate ammonium sulfate solution, and then the ammonium sulfate solution is reacted with calcium chloride to prepare gypsum whisker products, resulting in a cumbersome process. Summary of the invention

[0005] The present invention aims to provide a method for using industrial waste sulfuric acid and a system for preparing calcium sulfate whiskers, so as to solve the problem of complex process of preparing calcium sulfate whiskers using industrial waste sulfuric acid.

[0006] In a first aspect, a method for using industrial waste sulfuric acid is provided, comprising: obtaining an industrial waste sulfuric acid raw material and a calcium sulfate dihydrate powder raw material respectively; detecting the concentration of the industrial waste sulfuric acid raw material, and using the industrial waste sulfuric acid raw material as a standby industrial waste sulfuric acid when the concentration detection value of the industrial waste sulfuric acid raw material meets the set conditions, and adjusting the concentration of the industrial waste sulfuric acid raw material when the concentration detection value of the industrial waste sulfuric acid raw material does not meet the set conditions, and using the industrial waste sulfuric acid raw material whose adjusted concentration meets the set conditions as a standby industrial waste sulfuric acid; adding the standby industrial waste sulfuric acid and the calcium sulfate dihydrate powder raw material into a reaction container according to set addition amounts, and then fully stirring at 60°C-90°C to dissolve the calcium sulfate dihydrate powder raw material in the standby industrial waste sulfuric acid, and then cooling to obtain crystallized calcium sulfate whiskers and used industrial waste sulfuric acid; performing solid-liquid separation on the calcium sulfate whiskers and the used industrial waste sulfuric acid, and then utilizing the calcium sulfate whiskers and the used industrial waste sulfuric acid separately.

[0007] As an improvement and / or embodiment of the method for using industrial waste sulfuric acid in the first aspect, further: the calcium sulfate whiskers are output as a product.

[0008] As an improvement and / or instantiation of the method for using industrial waste sulfuric acid in the first aspect, further: the used industrial waste sulfuric acid is output as a product and / or returned to the industrial waste sulfuric acid raw material.

[0009] As an improvement and / or instantiation of the method for using industrial waste sulfuric acid in the first aspect mentioned above, further: the industrial waste sulfuric acid raw material is taken to the regeneration liquid storage tank of the catalytic flue gas desulfurization system.

[0010] As an improvement and / or instantiation of the method for using industrial waste sulfuric acid in the first aspect mentioned above, further: the concentration of the standby industrial waste sulfuric acid is 1 mol / L-3 mol / L by mole per liter; the ratio of the added amount of the standby industrial waste sulfuric acid to the added amount of the calcium sulfate dihydrate powder raw material is 50:1-80:1 by mole ratio.

[0011] As an improvement and / or instantiation of the method for using industrial waste sulfuric acid in the first aspect above, further: in addition to the spare industrial waste sulfuric acid and the calcium sulfate dihydrate powder raw material, cetyltrimethylammonium bromide and ethanol aqueous solution are added to the reaction container, and the ratio of the added amount of cetyltrimethylammonium bromide to the added amount of the spare industrial waste sulfuric acid is 0.003:1 to 0.005:1 in molar ratio, and the ethanol aqueous solution is used to promote the dispersion of the cetyltrimethylammonium bromide.

[0012] In a second aspect, a calcium sulfate whisker preparation system is provided, which is used to implement the method for using industrial waste sulfuric acid in the first aspect, comprising: an industrial waste sulfuric acid processing unit, comprising an industrial waste sulfuric acid storage tank and a sulfuric acid concentration analyzer, a sulfuric acid concentration regulating device and a sulfuric acid metering and outputting device arranged on the industrial waste sulfuric acid storage tank; a calcium sulfate dihydrate powder processing unit, comprising a calcium sulfate dihydrate powder storage tank and a calcium sulfate dihydrate powder metering and outputting device arranged on the calcium sulfate dihydrate powder storage tank; a reaction unit, comprising a reactor, wherein the feed port of the reactor is respectively connected to the sulfuric acid metering and outputting device and the calcium sulfate dihydrate powder metering and outputting device and has a temperature control device and a stirring device; a solid-liquid separation unit, comprising a solid-liquid separator, wherein the input port of the solid-liquid separator is connected to the output port of the reactor.

[0013] As an improvement and / or instantiation of the calcium sulfate whisker preparation system of the above-mentioned second aspect, further: the solid-liquid separator comprises a filter element and a filtered liquid pumping system connected to the filtered liquid output port of the filter element, the filter element is arranged in the reactor, and the filtered liquid pumping system is arranged outside the reactor.

[0014] As an improvement and / or instantiation of the calcium sulfate whisker preparation system of the second aspect, further: a reflux pipeline for conveying used industrial waste sulfuric acid is connected between the filtered liquid pumping system and the industrial waste sulfuric acid treatment unit.

[0015] As an improvement and / or instantiation of the calcium sulfate whisker preparation system of the second aspect mentioned above, further: the industrial waste sulfuric acid storage is connected to the regeneration liquid storage tank of the catalytic flue gas desulfurization system through an industrial waste sulfuric acid raw material transportation pipeline.

[0016] The method for using the above-mentioned industrial waste sulfuric acid and the system for preparing calcium sulfate whiskers provided by the present invention directly use industrial waste sulfuric acid and calcium sulfate dihydrate powder as raw materials to prepare calcium sulfate whiskers through an acid dissolution recrystallization method without the intermediate step of ammonium sulfate conversion. The process flow is simple, and the recycling of industrial waste sulfuric acid can be achieved, and calcium sulfate whisker products with economic value can be produced at the same time. This method not only solves the problem of industrial waste acid treatment, but also can create considerable economic benefits.

[0017] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be learned through practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of this specification are used to assist in understanding the present invention. The contents provided in the drawings and their related descriptions in this specification may be used to explain the present invention, but shall not constitute improper limitations on the present invention.

[0019] Figure 1 The present invention is a schematic diagram of the principle of a calcium sulfate whisker preparation system according to an embodiment of the present invention.

[0020] Figure 2 for Figure 1 The schematic diagram of the structure of the reactor in the calcium sulfate whisker preparation system is shown.

[0021] Figure 3 This is a microscopic photograph of the calcium sulfate whiskers prepared in Experimental Example 4 of this specification.

[0022] Figure 4 This is a microscopic photograph of the calcium sulfate whiskers prepared in Experimental Example 5 of this specification.

[0023] Figure 5 This is a product photo of calcium sulfate whiskers prepared by a method for using industrial waste sulfuric acid in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The present invention is described clearly and completely below in conjunction with the accompanying drawings. A person skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0025] The technical solutions and technical features provided in each section, including the following description, can be combined with each other without conflict. In addition, where possible, these technical solutions, technical features and related combinations can be assigned specific technical themes and protected by relevant patents.

[0026] The embodiments of the present invention involved in the following description are generally only a part of the embodiments rather than all the embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of patent protection.

[0027] Regarding the terms and units in this specification: The terms "include", "comprises", "have" and any variations thereof in this specification and the corresponding claims and related parts are intended to cover non-exclusive inclusions. In addition, other relevant terms and units can be reasonably interpreted based on the relevant content provided in this specification.

[0028] Figure 1 FIG. 1 is a schematic diagram of the principle of a calcium sulfate whisker preparation system according to an embodiment of the present invention. Figure 1As shown, a calcium sulfate whisker preparation system mainly includes four parts: an industrial waste sulfuric acid treatment unit 11, a calcium sulfate dihydrate powder treatment unit 12, a reaction unit 13 and a solid-liquid separation unit 14.

[0029] The industrial waste sulfuric acid treatment unit 11 includes an industrial waste sulfuric acid storage and a sulfuric acid concentration analyzer, a sulfuric acid concentration regulating device and a sulfuric acid metering output device arranged on the industrial waste sulfuric acid storage. The sulfuric acid concentration analyzer can specifically be an online sulfuric acid concentration analyzer. The sulfuric acid concentration regulating device can specifically use a peristaltic pump to accurately add acid or water to adjust the concentration. The sulfuric acid metering output device can specifically use a high-precision metering pump to measure and output sulfuric acid.

[0030] The industrial waste sulfuric acid treatment unit 11 can realize the temporary storage of industrial waste sulfuric acid raw materials and detect the concentration of the temporarily stored industrial waste sulfuric acid raw materials. When the concentration of the industrial waste sulfuric acid raw materials meets the set conditions, the industrial waste sulfuric acid raw materials are used as standby industrial waste sulfuric acid. When the concentration of the industrial waste sulfuric acid raw materials does not meet the set conditions, the concentration of the industrial waste sulfuric acid raw materials is adjusted and the industrial waste sulfuric acid raw materials whose adjusted concentration meets the set conditions are used as standby industrial waste sulfuric acid. The sulfuric acid metering output device of the industrial waste sulfuric acid treatment unit 11 can add the standby industrial waste sulfuric acid stored in the industrial waste sulfuric acid storage to the reaction container (in this embodiment, the reaction container is equivalent to the reactor in the reaction unit 13, the same below) according to the set addition amount.

[0031] In this embodiment, the industrial waste sulfuric acid storage is connected to the regeneration liquid storage tank of the catalytic flue gas desulfurization system 2 through the industrial waste sulfuric acid raw material delivery pipeline. Generally, the catalytic flue gas desulfurization system 2 has 3-4 regeneration liquid storage tanks, and these regeneration liquid storage tanks respectively store dilute sulfuric acid of different concentrations, and the concentration (mass percentage) of the most concentrated dilute sulfuric acid stored in these regeneration liquid storage tanks is about 15%-20%.

[0032] The calcium sulfate dihydrate powder processing unit 12 comprises a calcium sulfate dihydrate powder storage tank and a calcium sulfate dihydrate powder metering and outputting device arranged on the calcium sulfate dihydrate powder storage tank. The calcium sulfate dihydrate powder storage tank can specifically use a powder silo. The calcium sulfate dihydrate powder metering and outputting device can specifically use a loss-in-weight feeder.

[0033] The calcium sulfate dihydrate powder processing unit 12 can realize temporary storage of calcium sulfate dihydrate powder raw materials. The calcium sulfate dihydrate powder metering and output device of the calcium sulfate dihydrate powder processing unit 12 can add the calcium sulfate dihydrate powder raw materials stored in the calcium sulfate dihydrate powder storage device to the reaction container according to the set addition amount.

[0034] The reaction unit 13 comprises a reactor, the feed port of which is connected to the sulfuric acid metering output device and the calcium sulfate dihydrate powder metering output device respectively and has a temperature control device and a stirring device. During operation, the spare industrial waste sulfuric acid and the calcium sulfate dihydrate powder raw material are added to the reactor according to the set addition amount respectively, and the calcium sulfate dihydrate powder raw material can be fully stirred at 60°C-90°C through the temperature control device and stirring device of the reactor to dissolve the calcium sulfate dihydrate powder raw material in the spare industrial waste sulfuric acid, and then cooled to obtain crystallized calcium sulfate whiskers and used industrial waste sulfuric acid.

[0035] The solid-liquid separation unit 14 can perform solid-liquid separation on the calcium sulfate whiskers and the used industrial waste sulfuric acid, thereby obtaining the calcium sulfate whiskers and the used industrial waste sulfuric acid respectively. The solid-liquid separation unit 14 comprises a solid-liquid separator, and the input port of the solid-liquid separator is connected to the output port of the reactor.

[0036] The calcium sulfate whiskers can be output as a product. The used industrial waste sulfuric acid can be output as a product and / or returned to the industrial waste sulfuric acid raw material.

[0037] The calcium sulfate whisker preparation system directly uses industrial waste sulfuric acid and calcium sulfate dihydrate powder as raw materials to prepare calcium sulfate whiskers through acid dissolution and recrystallization, without the intermediate step of ammonium sulfate conversion. The process is simple, and the recycling of industrial waste sulfuric acid can be realized, and calcium sulfate whisker products with economic value can be produced. It not only solves the problem of industrial waste acid treatment, but also creates considerable economic benefits.

[0038] Figure 2 for Figure 1 The schematic diagram of the structure of the reactor in the calcium sulfate whisker preparation system is shown in FIG. Figure 2 As shown, the reactor has a tank body 131, and the outside of the tank body 131 is wrapped with a temperature control jacket 132. When working, the temperature control jacket 132 is passed through a heat exchange medium (such as hot water) to control the reaction temperature inside the tank body 131. A stirring device 133 (including a vertically arranged stirring shaft and blades distributed on the stirring shaft) is provided in the tank body 131, and the stirring shaft is driven by a motor 1331 arranged on the top of the tank body 131. A feed port 1311 (for inputting the spare industrial waste sulfuric acid and the calcium sulfate dihydrate powder raw material) is distributed on the top of the tank body 131, and an output port 1312 (the output port passes downward through the temperature control jacket 132) is provided at the bottom center of the tank body 131.

[0039] The key innovation of the reactor is that a filter element 141 is provided inside the tank body 131, and the filter element 141 serves as the filter element of the solid-liquid separator. Since the filter element of the solid-liquid separator is built into the tank body 131, the reactor and the solid-liquid separator are integrated.

[0040] Generally speaking, the filtered liquid output port of the filter element 141 is connected to a filtered liquid pumping system disposed outside the reactor to achieve filtering by the filter element 141 .

[0041] A return pipeline for conveying used industrial waste sulfuric acid can be connected between the filtered liquid pumping system and the industrial waste sulfuric acid treatment unit 11 (see Figure 1 ).

[0042] This integrated design can produce the following effects in the present invention: first, it simplifies the structure of the entire calcium sulfate whisker preparation system, reduces the material transfer link between equipment, thereby reducing energy consumption and material loss, and improving production efficiency. More importantly, this design ensures the environmental consistency of the reaction crystallization process: since acid dissolution, crystallization and separation are all carried out in the same closed system, key parameters such as temperature and stirring speed can be accurately controlled, so that the environmental conditions of the whole process remain stable and consistent. This environmental consistency is very important for producing high-quality, uniform calcium sulfate whiskers, and can improve the quality stability and batch consistency of the product. In addition, it saves space, reduces equipment investment costs, and reduces the risk of operators contacting hazardous chemicals by reducing the material transfer steps, thereby improving production safety.

[0043] As a specific solution for arranging the filter element 141 inside the tank body 131, Figure 2 As shown, multiple filter tubes (the filter tubes are directly commercially available) are arranged at intervals along the circumferential direction on the bottom edge of the tank body 131. Specifically, multiple bosses 134 (these bosses are directly welded to the bottom of the tank body 131) are arranged at intervals along the circumferential direction on the bottom edge of the tank body 131, and each boss 134 is provided with a filter element installation interface, and the lower end joint of the corresponding filter tube (i.e., the filtered liquid output port of the filter tube) is docked and installed on the corresponding filter element installation interface, and the filtrate output channel at the bottom of each filter element installation interface passes downward through the tank body 131 and then communicates with the guide tube 135 (the guide tube 135 is annularly arranged in this embodiment) arranged on the outer side of the bottom of the tank body 131, and the outlet of the guide tube 135 passes through the temperature control jacket 132.

[0044] The characteristics of the above specific scheme are: 1) Multiple filter tubes arranged vertically are arranged at intervals along the circumferential direction on the bottom edge of the tank body 131. When filtering through the filter tubes, the liquid level in the tank body 131 drops. As long as the liquid level in the tank body 131 is not lower than the bottom of the filter tubes, these filter tubes can still filter, thus ensuring the concentration efficiency of the solid-liquid separator. 2) The filter element 141 is installed through multiple bosses 134 arranged at intervals along the circumferential direction on the bottom edge of the tank body 131, and the guide tube 135 is arranged on the outside of the bottom of the tank body 131. This avoids the need to set a complex filter element installation guide structure inside the tank body 131, and can also prevent solid phase matter from accumulating and scaling at the bottom of the filter element 141, and can greatly facilitate the manufacturing and construction of the guide tube 135.

[0045] Using the calcium sulfate whisker preparation system, the present invention also provides a method for using industrial waste sulfuric acid. The method comprises:

[0046] 1. Obtain industrial waste sulfuric acid raw material and calcium sulfate dihydrate powder raw material respectively;

[0047] 2. Detecting the concentration of the industrial waste sulfuric acid raw material, and using the industrial waste sulfuric acid raw material as a backup industrial waste sulfuric acid when the concentration of the industrial waste sulfuric acid raw material meets the set conditions; and adjusting the concentration of the industrial waste sulfuric acid raw material when the concentration does not meet the set conditions and using the industrial waste sulfuric acid raw material whose adjusted concentration meets the set conditions as a backup industrial waste sulfuric acid;

[0048] 3. Adding the spare industrial waste sulfuric acid and the calcium sulfate dihydrate powder raw material into the reaction container according to the set addition amount, and then fully stirring at 60° C.-90° C. to dissolve the calcium sulfate dihydrate powder raw material in the spare industrial waste sulfuric acid, and then cooling to obtain crystallized calcium sulfate whiskers and used industrial waste sulfuric acid;

[0049] Fourth, the calcium sulfate whiskers and the used industrial waste sulfuric acid are separated into solid and liquid, and then the calcium sulfate whiskers and the used industrial waste sulfuric acid are respectively used for subsequent utilization.

[0050] Wherein, the subsequent utilization of the calcium sulfate whiskers may be: outputting the calcium sulfate whiskers as a product.

[0051] The subsequent utilization of the used industrial waste sulfuric acid may include: outputting the used industrial waste sulfuric acid as a product and / or returning the used industrial waste sulfuric acid to the industrial waste sulfuric acid raw material.

[0052] Experimental example

[0053] 1. Acid dissolution and recrystallization experiment of calcium sulfate whiskers.

[0054] I. Raw materials:

[0055] Calcium sulfate dihydrate, also known as raw gypsum, refers to natural dihydrate gypsum, white monoclinic crystals or crystalline powder. It is slightly soluble in acid and will crystallize out after being dissolved in sulfuric acid and cooled.

[0056] Hexadecyltrimethylammonium bromide (CTAB): Hexadecyltrimethylammonium bromide is a quaternary ammonium salt that is stable in acidic solutions. CTAB is a white powder that acts as a surfactant in this experiment, inhibiting the lateral growth of calcium sulfate whiskers, thereby preparing calcium sulfate whiskers with smaller diameters and uniformity.

[0057] II. Experimental Procedure:

[0058] Experimental Example 1: Weigh a certain amount of calcium sulfate dihydrate powder into a conical flask, and then weigh 500 ml of 1.455 mol / L dilute sulfuric acid and add it to the conical flask. Place the conical flask in a heat-collecting constant temperature heating magnetic stirrer at 80°C, stir at a stirring rate of 600 r / min for 1 hour, then take it out and place it at room temperature to cool naturally, and let it stand at room temperature for 20 hours until it is completely crystallized. The calcium sulfate whiskers obtained by standing are filtered under reduced pressure with medium-speed qualitative filter paper (pore size of 30-50 μm) and washed to neutrality, and finally the filter cake is dried in an oven at 60°C for 2 hours to obtain sample 1.

[0059] Experimental Example 2: Weigh a certain amount of calcium sulfate dihydrate powder into a conical flask, and then weigh 500 ml of 1.455 mol / L dilute sulfuric acid and add it to the conical flask. Place the conical flask in a heat-collecting constant temperature heating magnetic stirrer at 80°C, stir at a stirring rate of 600 r / min for 1 hour, then take it out and place it at room temperature to cool naturally, and let it stand at room temperature for 20 hours until it is completely crystallized. The calcium sulfate whiskers obtained by standing are filtered under reduced pressure with medium-speed qualitative filter paper (pore size of 30-50 μm) and washed until neutral, and finally the filter cake is dried in an oven at 60°C for 2 hours to obtain sample 2.

[0060] Experimental Example 3: Weigh a certain amount of calcium sulfate dihydrate powder into a conical flask, and then weigh 500 ml of 1.625 mol / L dilute sulfuric acid and add it to the conical flask. Place the conical flask in a heat-collecting constant temperature heating magnetic stirrer at 80°C, stir at a stirring rate of 600 r / min for 1 hour, then take it out and place it at room temperature to cool naturally, and let it stand at room temperature for 20 hours until it is completely crystallized. Filter the calcium sulfate whiskers obtained by standing under reduced pressure with medium-speed qualitative filter paper and wash them until they are neutral, and finally dry the filter cake in a 60°C oven for 2 hours to obtain sample 3.

[0061] Experimental Example 4: Weigh a certain amount of calcium sulfate dihydrate powder into a conical flask, and then weigh 500 ml of 1.625 mol / L dilute sulfuric acid and add it to the conical flask. Place the conical flask in a heat-collecting constant temperature heating magnetic stirrer at 80°C, stir at a stirring rate of 600 r / min for 1 hour, then take it out and place it at room temperature to cool naturally, and let it stand at room temperature for 20 hours until it is completely crystallized. The calcium sulfate whiskers obtained by standing are filtered under reduced pressure with medium-speed qualitative filter paper and washed until neutral, and finally the filter cake is dried in an oven at 60°C for 2 hours to obtain sample 4.

[0062] Experimental Example 5: Take an appropriate amount of calcium sulfate dihydrate powder and 0.020g of hexadecyltrimethylammonium bromide (CTAB) in a conical flask, then add 150ml of ethanol-water solution (2:1) to the conical flask, and then add 700ml of sulfuric acid (1.455mol / L). Place the conical flask in a heat-collecting constant temperature heating magnetic stirrer at 80°C, stir magnetically at a stirring rate of 600r / min for 1h, then take it out and place it at room temperature to cool and crystallize naturally. After 20h of crystallization, the calcium sulfate whisker is filtered under reduced pressure with medium-speed qualitative filter paper and washed to neutrality, and finally the filter cake is dried in an oven at 60°C for 2h to obtain sample 5. The role of the ethanol-water solution is to promote the dispersion of hexadecyltrimethylammonium bromide.

[0063] III. Experimental results:

[0064] See Table 1.

[0065] Table 1: Calcium sulfate whisker yields for each experimental example

[0066]

[0067] IV. Conclusion:

[0068] 1) The preferred conditions for the acid-soluble recrystallization of calcium sulfate whiskers in the present invention are: the sulfuric acid concentration is 1mol / L-3mol / L by mole per liter; the ratio of the addition of sulfuric acid to the addition of the calcium sulfate dihydrate is 50:1-80:1 by mole ratio (after calculation, the ratio of the addition of sulfuric acid to the addition of the calcium sulfate dihydrate in Experimental Example 1 is 35.66:1 by mole ratio, 51.23:1 in Experiment 2, 39.83:1 in Experiment 3, 55.65:1 in Experiment 4, and 71.72:1 in Experiment 5).

[0069] 2) The use of hexadecyltrimethylammonium bromide can inhibit the lateral growth of calcium sulfate whiskers, thereby preparing calcium sulfate whiskers with smaller diameter and uniformity (such as Figure 3 and Figure 4 As shown, the whisker length of sample 5 is about 20%-50% longer than that of sample 4).

[0070] 2. Pilot test of the method for using industrial waste sulfuric acid of the present invention.

[0071] The calcium sulfate whisker preparation system of the above embodiment is used, and the process conditions are referred to the above experimental example 4. The prepared calcium sulfate whisker product is as follows: Figure 5 The purity of the calcium sulfate whisker product was detected to be 99.4167%.

[0072] The above is a description of the relevant contents of the present invention. A person skilled in the art will be able to implement the present invention based on these descriptions. Based on the above contents of this specification, all other embodiments obtained by a person skilled in the art without making any creative work shall fall within the scope of patent protection.

Claims

1. A method for using industrial waste sulfuric acid, characterized in that: include: Respectively obtaining industrial waste sulfuric acid raw material and calcium sulfate dihydrate powder raw material; The concentration of the industrial waste sulfuric acid raw material is detected, and when the concentration of the industrial waste sulfuric acid raw material meets the set conditions, the industrial waste sulfuric acid raw material is used as a backup industrial waste sulfuric acid; when the concentration of the industrial waste sulfuric acid raw material does not meet the set conditions, the concentration of the industrial waste sulfuric acid raw material is adjusted and the industrial waste sulfuric acid raw material whose adjusted concentration meets the set conditions is used as the backup industrial waste sulfuric acid; The spare industrial waste sulfuric acid and the calcium sulfate dihydrate powder raw material are added into a reaction container according to set addition amounts, and then the calcium sulfate dihydrate powder raw material is fully stirred at 60° C.-90° C. to dissolve in the spare industrial waste sulfuric acid, and then cooled to obtain crystallized calcium sulfate whiskers and used industrial waste sulfuric acid; The calcium sulfate whiskers and the used industrial waste sulfuric acid are separated into solid and liquid, and then the calcium sulfate whiskers and the used industrial waste sulfuric acid are respectively used for subsequent utilization.

2. The method for using industrial waste sulfuric acid according to claim 1, characterized in that: The calcium sulfate whiskers are output as products.

3. The method for using industrial waste sulfuric acid according to claim 1, characterized in that: The used industrial waste sulfuric acid is output as a product and / or returned to the industrial waste sulfuric acid raw material.

4. The method for using industrial waste sulfuric acid according to any one of claims 1 to 3, characterized in that: The industrial waste sulfuric acid raw material is taken to the regeneration liquid storage tank of the catalytic flue gas desulfurization system.

5. The method for using industrial waste sulfuric acid according to any one of claims 1 to 3, characterized in that: The concentration of the spare industrial waste sulfuric acid is 1 mol / L-3 mol / L by mole per liter; the ratio of the added amount of the spare industrial waste sulfuric acid to the added amount of the calcium sulfate dihydrate powder raw material is 50:1-80:1 by mole ratio.

6. The method for using industrial waste sulfuric acid according to claim 5, characterized in that: In addition to the spare industrial waste sulfuric acid and the calcium sulfate dihydrate powder raw material, cetyltrimethylammonium bromide and ethanol aqueous solution are also added to the reaction container, and the ratio of the added amount of cetyltrimethylammonium bromide to the added amount of the spare industrial waste sulfuric acid is 0.003:1 to 0.005:1 in molar ratio, and the ethanol aqueous solution is used to promote the dispersion of the cetyltrimethylammonium bromide.

7. A calcium sulfate whisker preparation system, for implementing the method for using industrial waste sulfuric acid as claimed in any one of claims 1 to 6, characterized in that: include: An industrial waste sulfuric acid treatment unit comprises an industrial waste sulfuric acid storage tank and a sulfuric acid concentration analyzer, a sulfuric acid concentration regulating device and a sulfuric acid metering output device arranged on the industrial waste sulfuric acid storage tank; A calcium sulfate dihydrate powder processing unit comprises a calcium sulfate dihydrate powder storage tank and a calcium sulfate dihydrate powder metering and outputting device arranged on the calcium sulfate dihydrate powder storage tank; A reaction unit comprises a reactor, wherein the feed port of the reactor is respectively connected to the sulfuric acid metering output device and the calcium sulfate dihydrate powder metering output device and is provided with a temperature control device and a stirring device; The solid-liquid separation unit comprises a solid-liquid separator, wherein the input port of the solid-liquid separator is connected to the output port of the reactor.

8. The calcium sulfate whisker preparation system as claimed in claim 7, characterized in that: The solid-liquid separator comprises a filter element and a filtered liquid pumping system connected to a filtered liquid output port of the filter element. The filter element is arranged in the reactor, and the filtered liquid pumping system is arranged outside the reactor.

9. The calcium sulfate whisker preparation system as claimed in claim 8, characterized in that: A reflux pipeline for conveying used industrial waste sulfuric acid is connected between the filtered liquid pumping system and the industrial waste sulfuric acid treatment unit.

10. The calcium sulfate whisker preparation system as claimed in claim 7, characterized in that: The industrial waste sulfuric acid storage device is connected to the regeneration liquid storage tank of the catalytic flue gas desulfurization system through an industrial waste sulfuric acid raw material conveying pipeline.

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