System for producing calcium sulfate whiskers in zinc hydrometallurgy

Abstract

The invention discloses a system for producing calcium sulfate whiskers in zinc hydrometallurgy, and the system comprises a slurry preparation device which is used for carrying out slurrying treatment on limestone to obtain a limestone suspension; the reaction device is used for mixing the limestone suspension with an acidic solution and carrying out a neutralization reaction to obtain a calcium sulfate suspension; a pneumatic stirring device is arranged in the reaction device; the solid-liquid separation device is used for carrying out solid-liquid separation treatment on the calcium sulfate suspension so as to obtain calcium sulfate dihydrate; the drying device is used for carrying out drying treatment on the calcium sulfate dihydrate to obtain the calcium sulfate whiskers, and the length-diameter ratio of the calcium sulfate whiskers is 10-200. Therefore, by means of the system, not only can the residual acid in the zinc hydrometallurgy process be consumed, but also the high-quality desulfurized gypsum can be produced, the additional value of the desulfurized gypsum can be increased, and the desulfurized gypsum has higher economic value.

Description

Technical Field

[0001] The present application relates to the field of metallurgy technology, and in particular to a system for producing calcium sulfate whiskers in hydrometallurgy of zinc. Background Art

[0002] System acid balance is the key prerequisite for the smooth progress of the hydrometallurgical zinc smelting process and is also the core link in technical management. If the system acidity is too high, it will have a profound impact on the entire production process. Excessive acidity will cause a large amount of impurities in the raw materials to dissolve, which will not only reduce the purity of the raw materials, but also affect the purification effect of the solution. In addition, high acidity may also cause problems such as pipeline crystallization and electrolytic plate burning, and may even cause the entire production line to stop production.

[0003] It should be noted that the above statements are only used to provide background technical information related to the present application and do not necessarily constitute prior art. Summary of the invention

[0004] In the first aspect of the present application, the present application provides a system for producing calcium sulfate whiskers in wet zinc smelting, the system comprising: a slurry preparation device, the slurry preparation device is used to slurry limestone to obtain a limestone suspension; a reaction device, the reaction device is used to mix the limestone suspension with an acidic solution, and neutralize the reaction to obtain a calcium sulfate suspension; a pneumatic stirring device is provided in the reaction device; a solid-liquid separation device, the solid-liquid separation device is used to perform solid-liquid separation on the calcium sulfate suspension to obtain calcium sulfate dihydrate; a drying device, the drying device is used to dry the calcium sulfate dihydrate to obtain calcium sulfate whiskers, wherein the aspect ratio of the calcium sulfate whiskers is 10-200. Therefore, the system of the present application can not only consume the residual acid in the wet zinc smelting process, but also produce high-quality desulfurized gypsum, thereby increasing the added value of the desulfurized gypsum and making it have higher economic value.

[0005] In some embodiments, the pneumatic stirring device includes a plurality of vertical air inlet pipes perpendicular to the bottom surface of the reaction device and evenly arranged along the inner wall of the reaction device, and an annular air inlet pipe parallel to the bottom surface of the reaction device and coaxial with the reaction device; the vertical air inlet pipe and the annular air inlet pipe are independently provided with a plurality of air jets, and the air jet direction of the air jets is toward the axis of the reaction device. Thus, the gas injected into the reaction device from different directions generates turbulence and eddy currents, which can increase the contact probability between the reactants, thereby increasing the rate of the neutralization reaction.

[0006] In some embodiments, a first nozzle is disposed on the jet port of the vertical air inlet pipe, a first angle is formed between the first nozzle and the vertical air inlet pipe, the opening direction of the first angle is toward the bottom surface of the reaction device, and the first angle is an acute angle. Thus, the gas flow can be optimized, thereby improving the stirring effect and the neutralization reaction rate.

[0007] In some embodiments, a second nozzle is disposed on the jet port of the annular air inlet pipe, and a second angle is formed between the second nozzle and the bottom surface of the reaction device, and the second angle is an acute angle, thereby optimizing the gas flow, thereby improving the stirring effect and the neutralization reaction rate.

[0008] In some embodiments, the first angle is 40°-50°.

[0009] In some embodiments, the second angle is 40°-50°.

[0010] In some embodiments, the limestone suspension is mixed with an acidic solution, and a neutralization reaction is performed to obtain carbon dioxide, the purity of which is greater than 99.5%; the carbon dioxide is compressed to obtain high-pressure gas, and the high-pressure gas is introduced into the pneumatic stirring device to become the gas source of the pneumatic stirring device. Thus, the carbon dioxide generated by the neutralization reaction can be reused.

[0011] In some embodiments, the reaction device comprises a first reaction tank, a second reaction tank, and a third reaction tank, wherein the water outlet of the first reaction tank is connected to the water inlet of the second reaction tank, and the water outlet of the second reaction tank is connected to the water inlet of the third reaction tank, and the acidity of the first reaction tank, the second reaction tank, and the third reaction tank is controlled so that H + The concentration of H in the second reaction tank is 100g / L-130g / L. + The concentration of H in the third reaction tank is 50g / L-100g / L. + The concentration is 40g / L-50g / L. Therefore, the segmented continuous reaction process makes it easier for operators to monitor and adjust the entire reaction process to cope with fluctuations in the production process and promote stable reaction.

[0012] In some embodiments, the acidic solution includes spent electrolyte, and the concentration of H2SO4 in the spent electrolyte is 100 g / L-300 g / L.

[0013] In some embodiments, the limestone satisfies at least one of the following conditions: based on the total mass of the limestone, the mass fraction of the limestone after screening through a 200-mesh screen is 100%; based on the total mass of the limestone, the mass fraction of the limestone after screening through a 300-mesh screen is greater than or equal to 80%; based on the total mass of the limestone, the mass fraction of calcium carbonate in the limestone is greater than or equal to 97%. Thus, improving the fineness and uniformity of the limestone particles helps the limestone particles to contact the acidic solution more fully and more uniformly, thereby improving the efficiency of the neutralization reaction.

[0014] In some embodiments, the reaction temperature of the neutralization reaction is 70° C.-100° C., and the reaction time of the neutralization reaction is 3 h-10 h. Thus, selecting an appropriate reaction temperature and reaction time can accelerate the neutralization reaction rate.

[0015] In some embodiments, the drying temperature of the drying process is 150° C.-200° C., and the drying time of the drying process is 3 h-10 h. Thus, by selecting appropriate drying temperature and drying time, the drying rate can be increased.

[0016] In some embodiments, the calcium sulfate dihydrate is returned to the reaction device to become the seed crystal of the neutralization reaction, thereby inducing the nucleation and growth of new calcium sulfate crystals and increasing the neutralization reaction rate.

[0017] In some embodiments, the calcium sulfate whisker satisfies at least one of the following conditions: the whiteness of the calcium sulfate whisker is 90%-99%; the mass fraction of calcium sulfate in the calcium sulfate whisker is greater than or equal to 98%; the pH of the calcium sulfate whisker is 6.5-8.0. Thus, the present application can obtain high-quality calcium sulfate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0019] Figure 1 It is a schematic structural diagram of a system for producing calcium sulfate whiskers in hydrometallurgy of zinc in one embodiment of the present application.

[0020] Description of reference numerals:

[0021] 1. Slurry preparation tank; 11. Feed funnel; 12. Agitator; 13. Liquid pump; 2. Continuous reaction tank; 21. First reaction tank; 211. First liquid inlet pipe; 212. Vertical air inlet pipe; 213. Annular air inlet pipe; 22. Second reaction tank; 221. Second liquid inlet pipe; 23. Third reaction tank; 231. Third liquid inlet pipe; 24. Fourth reaction tank; 241. Fourth liquid inlet pipe; 3. Exhaust fan; 4. Electric demisting; 5. Drying tower; 6. Liquid carbon dioxide preparation tank; 7. Liquid carbon dioxide storage tank; 8. Compressor; 9. Gas storage tank; 91. Pressure reducing valve. DETAILED DESCRIPTION

[0022] Hereinafter, the embodiment of the system for producing calcium sulfate whiskers in the hydrometallurgical zinc smelting of the present application will be described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0023] " Scope " disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be to include end values ​​or not include end values, and can be combined arbitrarily, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a particular parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 listed, and if the maximum range values ​​3,4 and 5 are listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0024] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0025] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0026] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0027] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. "First feature" and "second feature" may include one or more of the features.

[0028] In the description of the present application, "A and / or B" may include the case of A alone, the case of B alone, or any of the cases of A and B, where A and B are only used for examples and may be any technical feature connected by "and / or" in the present application.

[0029] In order to maintain the acid balance of the system, lime or limestone is usually used to neutralize the residual acid during the wet zinc smelting process. This method can consume the excess acid in the system through neutralization reaction. However, a large amount of by-product desulfurization gypsum (calcium sulfate) will be produced in this process, and only about 20% of the desulfurization gypsum is effectively utilized. A large amount of desulfurization gypsum that does not meet the quality standards is mainly stored in piles. The abandoned desulfurization gypsum not only occupies a large amount of land resources, but also the harmful substances in the desulfurization gypsum will enter the groundwater system with rainwater, which can easily cause soil and water environment pollution. Therefore, improving the quality of desulfurization gypsum to increase its high added value has become an urgent problem to be solved.

[0030] In the first aspect of the present application, the present application provides a system for producing calcium sulfate whiskers in hydrometallurgy, the system comprising: a slurry preparation device, a reaction device, a solid-liquid separation device and a drying device. The slurry preparation device is used to slurry limestone to obtain a limestone suspension; the reaction device is used to mix the limestone suspension with an acidic solution, and neutralize the mixture to obtain a calcium sulfate suspension; a pneumatic stirring device is provided in the reaction device; the solid-liquid separation device is used to perform solid-liquid separation on the calcium sulfate suspension to obtain calcium sulfate dihydrate; and the drying device is used to dry the calcium sulfate dihydrate to obtain calcium sulfate whiskers.

[0031] Thus, the slurry preparation device slurries the limestone into a limestone suspension, providing a uniform limestone suspension for the subsequent neutralization reaction; thereafter, in the reaction device, the limestone suspension and the acidic solution undergo a neutralization reaction to generate calcium sulfate, and while the neutralization reaction is ongoing, the use of a pneumatic stirring device can reduce the damage to the calcium sulfate crystal form, thereby promoting the growth of calcium sulfate crystals; then the solid-liquid separation device performs solid-liquid separation on the calcium sulfate suspension to obtain calcium sulfate dihydrate; finally, the drying device dries the calcium sulfate dihydrate, removes the water and crystallization water attached to the calcium sulfate dihydrate, and obtains calcium sulfate whiskers with an aspect ratio of 10-200. Therefore, the system of the present application can not only consume the residual acid in the hydrometallurgical zinc smelting process, but also produce high-quality desulfurized gypsum, thereby increasing the added value of the desulfurized gypsum and making it have higher economic value.

[0032] In some embodiments, reference Figure 1 The slurry preparation device includes a slurry preparation tank 1, and the slurry preparation tank 1 includes a feeding funnel 11 arranged on the top of the slurry preparation tank 1, and the feeding funnel 11 can add limestone and water into the slurry preparation tank 1.

[0033] In some embodiments, a stirrer 12 is disposed in the slurry preparation tank 1 , and the stirring action of the stirrer 12 can fully mix the limestone and water to form a uniform limestone suspension.

[0034] In some embodiments, the limestone satisfies at least one of the following conditions: based on the total mass of the limestone, the mass fraction of the limestone after being screened through a 200-mesh screen is 100%; based on the total mass of the limestone, the mass fraction of the limestone after being screened through a 300-mesh screen is greater than or equal to 80%. Thus, improving the fineness and uniformity of the limestone particles helps the limestone particles to contact the acidic solution more fully and more uniformly, thereby improving the efficiency of the neutralization reaction.

[0035] As an example, based on the total mass of the limestone, the mass fraction of the limestone after being sieved through a 300-mesh screen may be 80%, 85%, 90%, 95% or 100%.

[0036] In some embodiments, the mass fraction of calcium carbonate in the limestone is greater than or equal to 97% based on the total mass of the limestone, thereby improving the purity of the reactants and reducing the introduction of impurities to improve the purity and whiteness of the calcium sulfate whiskers.

[0037] As an example, the mass fraction of calcium carbonate in the limestone may be 97%, 98%, 99% or 100% based on the total mass of the limestone.

[0038] In some embodiments, the limestone satisfies the following conditions simultaneously: based on the total mass of the limestone, the mass fraction of the limestone after screening through a 200-mesh sieve is 100%; based on the total mass of the limestone, the mass fraction of the limestone after screening through a 300-mesh sieve is greater than or equal to 80%; based on the total mass of the limestone, the mass fraction of calcium carbonate in the limestone is greater than or equal to 97%.

[0039] In some embodiments, the reaction device includes continuous reaction tanks 2, and the number of the continuous reaction tanks 2 is greater than 3.

[0040] As an example, the number of the continuous reaction tanks 2 includes, but is not limited to, 4, 5, 6 or 7.

[0041] In some embodiments, reference Figure 1 The continuous reaction tank 2 includes a first reaction tank 21 , a second reaction tank 22 , a third reaction tank 23 , and a fourth reaction tank 24 .

[0042] Understandably, Figure 1 The solid lines between the devices are the flow pipelines of the liquid, and the arrows indicate the flow direction of the liquid.

[0043] In some embodiments, a first liquid inlet pipe 211 is provided in the first reaction tank 21, the first liquid inlet pipe 211 vertically penetrates into the first reaction tank 21, and the first liquid inlet pipe 211 is connected to the water outlet of the slurry preparation tank 1 through a pipeline; a second liquid inlet pipe 221 is provided in the second reaction tank 22, the second liquid inlet pipe 221 vertically penetrates into the second reaction tank 22, and the second liquid inlet pipe 221 is connected to the water outlet of the slurry preparation tank 1 through a pipeline; a third liquid inlet pipe 231 is provided in the third reaction tank 23, the third liquid inlet pipe 231 vertically penetrates into the third reaction tank 23, and the third liquid inlet pipe 231 is connected to the water outlet of the slurry preparation tank 1 through a pipeline; a fourth liquid inlet pipe 241 is provided in the fourth reaction tank 24, the fourth liquid inlet pipe 241 vertically penetrates into the fourth reaction tank 24, and the fourth liquid inlet pipe 241 is connected to the water outlet of the slurry preparation tank 1 through a pipeline. Thus, the limestone suspension in the slurry preparation tank 1 flows into the first reaction tank 21 through the first liquid inlet pipe 211, the limestone suspension in the slurry preparation tank 1 flows into the second reaction tank 22 through the second liquid inlet pipe 221, the limestone suspension in the slurry preparation tank 1 flows into the third reaction tank 23 through the third liquid inlet pipe 231, and the limestone suspension in the slurry preparation tank 1 flows into the fourth reaction tank 24 through the fourth liquid inlet pipe 241.

[0044] In some embodiments, a liquid pump 13 is further provided on the pipeline at the water outlet of the slurry preparation tank 1 , and the liquid pump 13 facilitates pumping the limestone suspension in the slurry preparation tank 1 into the continuous reaction tank 2 .

[0045] In some embodiments, the acidic solution flows into the first reaction tank 21 from the water inlet of the first reaction tank 21, the water outlet of the first reaction tank 21 is connected to the water inlet of the second reaction tank 22 through a pipeline, the water outlet of the second reaction tank 22 is connected to the water inlet of the third reaction tank 23 through a pipeline, and the water outlet of the third reaction tank 23 is connected to the water inlet of the fourth reaction tank 24 through a pipeline. Thus, the acidic solution first enters the first reaction tank 21, and as the system runs, the acidic solution overflows step by step and flows into the second reaction tank 22, the third reaction tank 23, and the fourth reaction tank 24 in sequence.

[0046] In some embodiments, the acidity of the first reaction tank 21, the second reaction tank 22, and the third reaction tank 23 is controlled so that H + The concentration of H in the second reaction tank 22 is 100g / L-130g / L. + The concentration of H in the third reaction tank 23 is 50 g / L-100 g / L. + The concentration is 40g / L-50g / L. Therefore, the segmented continuous reaction process makes it easier for operators to monitor and adjust the entire reaction process to cope with fluctuations in the production process and promote stable reaction.

[0047] As an example, H in the first reaction tank 21 + The concentration can be 100 g / L, 110 g / L, 120 g / L or 130 g / L.

[0048] As an example, H in the second reaction tank 22 + The concentration can be 50g / L, 60g / L, 70g / L, 80g / L, 90g / L or 100g / L.

[0049] As an example, H in the third reaction tank 23 + The concentration can be 40g / L, 42g / L, 44g / L, 46g / L, 48g / L or 50g / L.

[0050] In some embodiments, the acidic solution includes spent electrolyte, and the concentration of H2SO4 in the spent electrolyte is 100 g / L-300 g / L.

[0051] As an example, the concentration of H2SO4 in the spent electrolyte may be 100 g / L, 150 g / L, 200 g / L, 250 g / L or 300 g / L.

[0052] In some embodiments, the spent electrolyte further comprises Zn 2+ , Zn in the spent electrolyte 2+ The concentration is 10g / L-100g / L.

[0053] As an example, Zn in spent electrolyte2+ The concentration can be 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L or 100 g / L.

[0054] In some embodiments, the water outlet of the first reaction tank 21 is opened at a position of the tank wall of the first reaction tank 21 near the top of the first reaction tank 21; the water inlet of the second reaction tank 22 and the water outlet of the second reaction tank 22 are respectively opened at a position of the tank wall of the second reaction tank 22 near the top of the second reaction tank 22, and the water inlet of the second reaction tank 22 is opposite to the water outlet of the second reaction tank 22; the water inlet of the third reaction tank 23 and the water outlet of the third reaction tank 23 are respectively opened at a position of the tank wall of the third reaction tank 23 near the top of the third reaction tank 23, and the water inlet of the third reaction tank 23 is opposite to the water outlet of the third reaction tank 23. The water inlet of the fourth reaction tank 24 and the water outlet of the fourth reaction tank 24 are respectively opened at a position of the tank wall of the fourth reaction tank 24 near the top of the fourth reaction tank 24, and the water inlet of the fourth reaction tank 24 is opposite to the water outlet of the fourth reaction tank 24. Thus, it is helpful for the acidic solution to overflow backward step by step.

[0055] In some embodiments, a water outlet pipe is provided in the first reaction tank 21, which extends vertically into the bottom of the first reaction tank 21 and is connected to the water outlet of the first reaction tank 21. Thus, the calcium sulfate suspension generated in the first reaction tank 21 is facilitated to flow into the second reaction tank 22. The second reaction tank 22, the third reaction tank 23, and the fourth reaction tank 24 are independently provided with water outlet pipes with the same structure as that of the first reaction tank 21, so they are not described in detail.

[0056] In some embodiments, the reaction temperature of the neutralization reaction is 70° C.-100° C., and the reaction time of the neutralization reaction is 3 h-10 h. Thus, selecting an appropriate reaction temperature and reaction time can accelerate the neutralization reaction rate.

[0057] As an example, the reaction temperature of the neutralization reaction may be 70°C, 80°C, 90°C, or 100°C.

[0058] As an example, the reaction time of the neutralization reaction can be 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h.

[0059] In some embodiments, taking the first reaction tank 21 as an example, refer to Figure 1The pneumatic stirring device includes a plurality of vertical air inlet pipes 212 which are perpendicular to the bottom surface of the first reaction tank 21 and are evenly arranged along the inner wall of the first reaction tank 21, and an annular air inlet pipe 213 which is parallel to the bottom surface of the first reaction tank 21 and coaxial with the first reaction tank 21; a plurality of jet ports are independently distributed on the vertical air inlet pipe 212 and the annular air inlet pipe 213, and the jetting direction of the jet ports is toward the axis of the first reaction tank 21. Thus, the gas injected into the first reaction tank 21 from different directions generates turbulence and eddy current, which can increase the contact probability between the reactants, thereby improving the rate of the neutralization reaction.

[0060] In some embodiments, a first nozzle is disposed on the jet port of the vertical air inlet pipe 212, and a first angle is formed between the first nozzle and the vertical air inlet pipe 212, and the opening direction of the first angle is toward the bottom surface of the first reaction tank 21, and the first angle is an acute angle. Thus, the gas flow can be optimized, thereby improving the stirring effect and the neutralization reaction rate.

[0061] In some embodiments, a second nozzle is disposed on the jet port of the annular air inlet pipe 213, and a second angle is formed between the second nozzle and the bottom surface of the first reaction tank 21, and the second angle is an acute angle, thereby optimizing the gas flow, thereby improving the stirring effect and the neutralization reaction rate.

[0062] In some embodiments, the first angle is 40°-50°. As an example, the first angle can be 40°, 42°, 44°, 46°, 48° or 50°.

[0063] In some embodiments, the second angle is 40°-50°. As an example, the second angle can be 40°, 42°, 44°, 46°, 48° or 50°.

[0064] The neutralization reaction generates carbon dioxide gas. In some embodiments, the system of the present application further includes a gas collection device, which is used to collect the carbon dioxide gas generated by the reaction device. Figure 1 The gas collecting device is an exhaust fan 3, and the air inlet of the exhaust fan 3 is independently connected to the first reaction tank 21, the second reaction tank 22, the third reaction tank 23, and the fourth reaction tank 24 through pipelines.

[0065] Understandably, Figure 1 The dotted lines between the devices are the flow pipelines of carbon dioxide, and the arrows indicate the flow direction of the carbon dioxide liquid.

[0066] In some embodiments, the system of the present application further comprises a purification system, and the purification system is used to purify impurities and moisture in the carbon dioxide gas. Figure 1The purification system includes an electric mist eliminator 4 and a drying tower 5. The air outlet of the exhaust fan 3 is connected to the air inlet of the electric mist eliminator 4 through a pipeline, and the air outlet of the electric mist eliminator 4 is connected to the air inlet of the drying tower 5 through a pipeline. After the carbon dioxide gas is impurities removed by the electric mist eliminator 4 and moisture is removed by the drying tower 5, pure carbon dioxide gas is obtained.

[0067] In some embodiments, the purity of the carbon dioxide is greater than 99.5%. As an example, the purity of the carbon dioxide can be 99.6%, 99.7%, 99.8%, 99.9% or 100%.

[0068] In some embodiments, the system of the present application further comprises a liquid carbon dioxide preparation tank 6 and a liquid carbon dioxide storage tank 7, thereby converting carbon dioxide from a gaseous state into a liquid state, facilitating the storage and transportation of carbon dioxide. Figure 1 The air inlet of the liquid carbon dioxide storage tank 7 is connected to the air outlet of the drying tower 5 through a pipeline, and the air inlet of the liquid carbon dioxide storage tank 7 is connected to the air outlet of the liquid carbon dioxide storage tank 7 through a pipeline.

[0069] In some embodiments, the system of the present application further comprises a gas compression device, which is used to compress the carbon dioxide gas to make it a high-pressure gas. Figure 1 The gas compression device includes a compressor 8, and the air inlet of the compressor 8 is connected to the pipeline between the drying tower 5 and the liquid carbon dioxide preparation tank 6.

[0070] In some embodiments, reference Figure 1 The system of the present application further includes an air storage tank 9, the air inlet of the air storage tank 9 is connected to the air outlet of the compressor 8 through a pipeline, so that the air storage tank 9 can store high-pressure gas. The air outlet of the air storage tank 9 is connected to the air inlets of the vertical air inlet pipe 212 and the annular air inlet pipe 213 through a pipeline, so that the high-pressure gas is introduced into the pneumatic stirring device to become the air source of the pneumatic stirring device.

[0071] In some embodiments, reference Figure 1 A pressure reducing valve 91 is provided on the pipeline between the gas storage tank 9 and the vertical air inlet pipe 212 or the annular air inlet pipe 213. The pressure reducing valve 91 reduces the high pressure gas to a pressure suitable for the pneumatic stirring device. Thus, the pure carbon dioxide gas can become the gas source of the pneumatic stirring device after passing through the compressor 8, the gas storage tank 9 and the pressure reducing valve 91.

[0072] In some embodiments, the height of the air pipe of the compressor 8 should be higher than the tank surface height of the continuous reaction tank 2, thereby reducing the back suction of the solution.

[0073] In some embodiments, the solid-liquid separation device includes a thickener, which utilizes the difference in specific gravity of solid particles in the suspension to settle to the bottom of the tank by gravity to form a dense bed layer, and uses filter media (such as filter cloth, filter plate, etc.) to intercept solid particles and allow liquid to pass through, thereby achieving the purpose of solid-liquid separation. Figure 1 The thickener can be connected to the water outlet of the fourth reaction tank 24, and the thickener is used to perform solid-liquid separation on the calcium sulfate suspension to obtain a sedimentation underflow, which contains calcium sulfate dihydrate.

[0074] In some embodiments, the sedimentation underflow is returned to the reaction device to become a seed crystal for the neutralization reaction. Thus, the calcium sulfate dihydrate in the sedimentation underflow can induce the nucleation and growth of new calcium sulfate crystals, thereby increasing the neutralization reaction rate.

[0075] In some embodiments, the sedimentation underflow volume of the return reaction device is 10%-40% of the volume of the calcium sulfate suspension. As an example, the sedimentation underflow volume of the return reaction device can be 10%, 20%, 30% or 40% of the volume of the calcium sulfate suspension.

[0076] In some embodiments, the system of the present application further comprises a washing device, which comprises a washing tank, and the washing tank is used to wash impurities in the sedimentation underflow, so that the impurities attached to the surface of the calcium sulfate dihydrate are dissolved in water.

[0077] In some embodiments, the washing tank and the continuous reaction tank 2 have the same structure, and a pneumatic stirring device is provided in the washing tank. The gas source of the pneumatic stirring device may also be the carbon dioxide gas generated by the neutralization reaction.

[0078] In some embodiments, the system of the present application further comprises a centrifuge, the solution in the washing tank enters the centrifuge, and the centrifuge is used to separate calcium sulfate dihydrate and water.

[0079] In some embodiments, the drying device includes a drying kiln, and the drying kiln is used to dry calcium sulfate dihydrate to obtain calcium sulfate whiskers.

[0080] In some embodiments, the drying temperature of the drying process is 150° C.-200° C., and the drying time of the drying process is 3 h-10 h. Thus, by selecting appropriate drying temperature and drying time, the drying rate can be accelerated.

[0081] In some embodiments, the calcium sulfate whiskers meet at least one of the following conditions: the whiteness of the calcium sulfate whiskers is 90%-99%; the mass fraction of calcium sulfate in the calcium sulfate whiskers is greater than or equal to 98%; the pH of the calcium sulfate whiskers is 6.5-8.0. Thus, the present application can obtain high-quality calcium sulfate.

[0082] As an example, the calcium sulfate whiskers may have a whiteness of 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%.

[0083] As an example, the mass fraction of calcium sulfate in the calcium sulfate whiskers may be 98%, 99% or 100%.

[0084] As an example, the pH of the calcium sulfate whiskers may be 6.5, 7, 7.5, or 8.0.

[0085] In summary, the present application adopts the limestone neutralization method to maintain the acid balance of the wet zinc smelting system, and can produce high-quality calcium sulfate whiskers, realize the high-value utilization of desulfurized gypsum, and is beneficial to improving the economic benefits of the enterprise; at the same time, the reaction exhaust gas is efficiently recycled and utilized to realize the productization of carbon dioxide. There is no waste residue, wastewater, or waste gas output in the process, which meets the requirements of cleanliness, environmental protection, energy conservation, and emission reduction.

[0086] The scheme of the present application is described below by specific examples. It should be noted that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If no specific technology or conditions are specified in the examples, the technology or conditions described in the literature in this area or the product instructions are used. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained commercially.

[0087] Example 1

[0088] In this embodiment, five continuous reaction tanks 2 are provided, namely a first reaction tank 21 , a second reaction tank 22 , a third reaction tank 23 , a fourth reaction tank 24 , and a fifth reaction tank.

[0089] Take limestone powder (based on the total mass of limestone, the mass fraction of limestone after screening through a 200-mesh screen is 100%, the mass fraction of limestone after screening through a 300-mesh screen is 85.67%, and the mass fraction of calcium carbonate in the limestone is 98.5%), add it to the slurry preparation tank 1 to slurry into a limestone suspension; then add the limestone suspension to the first reaction tank 21, the second reaction tank 22, and the third reaction tank 23 respectively, and continuously add the waste electrolyte to the first reaction tank 21 (the concentration of H2SO4 in the waste electrolyte is 165.45 g / L, the concentration of Zn in the waste electrolyte is 165.45 g / L) 2+The concentration is 165.45g / L); after the continuous reaction tank 2 reacts at 93°C for 5h, the slurry in the fifth reaction tank enters the thickener for sedimentation treatment for 10h to obtain a sedimentation underflow containing calcium sulfate whiskers; 15% of the sedimentation underflow returns to the first reaction tank 21, and 85% of the sedimentation underflow enters the washing tank for two-stage countercurrent washing and then enters the drying kiln for calcination. The calcination temperature is controlled at 180°C. After calcination for 4h, calcium sulfate whiskers are obtained. The carbon dioxide gas generated in the continuous reaction tank 2 is successively led to the electric demisting 4 and the drying tower 5 by the exhaust fan 3, and the purity of the gas CO2 is 99.67%. The gas CO2 can be treated as liquid CO2, or it can be returned to the continuous reaction tank 2 as a gas source for neutralization reaction.

[0090] After the system ran continuously for 24 hours, the calcium sulfate whiskers were sampled and tested. The calcium sulfate whiskers appeared as needle-shaped fibers under a microscope. The average length of the calcium sulfate whiskers was 10μm-80μm, the average diameter was 1μm-4μm, the mass fraction of calcium sulfate whiskers with an aspect ratio of 20-80 was 92.84%, the whiteness was 93%, the purity was 98.9%, and the pH was 6.8.

[0091] Example 2

[0092] In this embodiment, four continuous reaction tanks 2 are provided, namely a first reaction tank 21 , a second reaction tank 22 , a third reaction tank 23 , and a fourth reaction tank 24 .

[0093] Take limestone powder (based on the total mass of limestone, the mass fraction of limestone after screening through a 200-mesh screen is 100%, the mass fraction of limestone after screening through a 300-mesh screen is 90.65%, and the mass fraction of calcium carbonate in the limestone is 97.8%), add it to the slurry preparation tank 1 to slurry into a limestone suspension; then add the limestone suspension to the first reaction tank 21, the second reaction tank 22, and the third reaction tank 23 respectively, and continuously add the waste electrolyte to the first reaction tank 21 (the concentration of H2SO4 in the waste electrolyte is 170.84 g / L, the concentration of Zn in the waste electrolyte is 170.84 g / L) 2+ The concentration is 48.70g / L); after the continuous reaction tank 2 reacts at 86°C for 3h, the slurry in the fourth reaction tank 24 enters the thickener for sedimentation treatment for 10h to obtain a sedimentation underflow containing calcium sulfate whiskers; 20% of the sedimentation underflow returns to the first reaction tank 21, 10% of the sedimentation underflow returns to the second reaction tank 22, and 70% of the sedimentation underflow enters the washing tank for three-stage countercurrent washing and then enters the drying kiln for calcination. The calcination temperature is controlled at 165°C. After calcination for 4h, calcium sulfate whiskers are obtained. The carbon dioxide gas generated in the continuous reaction tank 2 is successively led to the electric demisting 4 and the drying tower 5 by the exhaust fan 3, and the purity of the gas CO2 is 99.81%. The gas CO2 can be treated as liquid CO2, or it can be returned to the continuous reaction tank 2 as a gas source for neutralization reaction.

[0094] After the system ran continuously for 24 hours, the calcium sulfate whiskers were sampled and tested. The calcium sulfate whiskers appeared as needle-shaped fibers under a microscope. The average length of the calcium sulfate whiskers was 30μm-100μm, the average diameter was 1μm-3μm, the mass fraction of calcium sulfate whiskers with an aspect ratio of 30-100 was 95.63%, the whiteness was 92%, the purity was 98.22%, and the pH was 7.5.

[0095] Example 3

[0096] In this embodiment, six continuous reaction tanks 2 are provided, namely a first reaction tank 21, a second reaction tank 22, a third reaction tank 23, a fourth reaction tank 24, a fifth reaction tank, and a sixth reaction tank.

[0097] Take limestone powder (based on the total mass of limestone, the mass fraction of limestone after screening through a 200-mesh sieve is 100%, the mass fraction of limestone after screening through a 300-mesh sieve is 95.34%, and the mass fraction of calcium carbonate in limestone is 98.05%), add it to the slurry preparation tank 1 to slurry into a limestone suspension; then add the limestone suspension to the first reaction tank 21, the second reaction tank 22, and the third reaction tank 23 respectively, and continuously add the waste electrolyte to the first reaction tank 21 (the concentration of H2SO4 in the waste electrolyte is 200.45 g / L, the concentration of Zn in the waste electrolyte is 200.45 g / L); 2+ The concentration is 50.64g / L); after the continuous reaction tank 2 reacts at 98°C for 8h, the slurry in the sixth reaction tank enters the thickener for sedimentation treatment for 10h to obtain a sedimentation underflow containing calcium sulfate whiskers; 20% of the sedimentation underflow returns to the first reaction tank 21, 10% of the sedimentation underflow returns to the second reaction tank 22, 10% of the sedimentation underflow returns to the third reaction tank 23, and 60% of the sedimentation underflow enters the washing tank for three-stage countercurrent washing and then enters the drying kiln for calcination. The calcination temperature is controlled at 190°C. After calcination for 4h, calcium sulfate whiskers are obtained. The carbon dioxide gas generated in the continuous reaction tank 2 is successively led to the electric demisting 4 and the drying tower 5 by the exhaust fan 3, and the purity of the gas CO2 is 99.82%. The gas CO2 can be treated as liquid CO2, or it can be returned to the continuous reaction tank 2 as a gas source for neutralization reaction.

[0098] After the system ran continuously for 24 hours, the calcium sulfate whiskers were sampled and tested. The calcium sulfate whiskers appeared as needle-shaped fibers under a microscope. The average length of the calcium sulfate whiskers was 30μm-200μm, the average diameter was 1μm-6μm, the mass fraction of the calcium sulfate whiskers with an aspect ratio of 40-180 was 93.57%, the whiteness was 95%, the purity was 98.76%, and the pH was 8.0.

[0099] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A system for producing calcium sulfate whiskers in hydrometallurgy of zinc, characterized in that: The system comprises: A slurry preparation device, wherein the slurry preparation device is used to slurry the limestone to obtain a limestone suspension; A reaction device, the reaction device is used to mix the limestone suspension with an acidic solution and neutralize it to obtain a calcium sulfate suspension; the reaction device is provided with a pneumatic stirring device; A solid-liquid separation device, which is used to perform solid-liquid separation on the calcium sulfate suspension to obtain calcium sulfate dihydrate; A drying device is used to dry the calcium sulfate dihydrate to obtain calcium sulfate whiskers, wherein the aspect ratio of the calcium sulfate whiskers is 10-200.

2. The system according to claim 1, characterized in that The pneumatic stirring device includes a plurality of vertical air inlet pipes perpendicular to the bottom surface of the reaction device and evenly arranged along the inner wall of the reaction device, and an annular air inlet pipe parallel to the bottom surface of the reaction device and coaxial with the reaction device; a plurality of jet ports are independently distributed on the vertical air inlet pipe and the annular air inlet pipe, and the jet direction of the jet port is toward the axis of the reaction device.

3. The system according to claim 2, characterized in that A first nozzle is provided on the jet port of the vertical air inlet pipe, a first angle is formed between the first nozzle and the vertical air inlet pipe, the opening direction of the first angle is toward the bottom surface of the reaction device, and the first angle is an acute angle; and / or, A second nozzle is arranged on the air injection port of the annular air inlet pipe, and a second angle is formed between the second nozzle and the bottom surface of the reaction device, and the second angle is an acute angle.

4. The system according to claim 3, characterized in that The first angle is 40°-50°; and / or, The second angle is 40°-50°.

5. The system according to any one of claims 1 to 4, characterized in that: The limestone suspension is mixed with an acidic solution and subjected to a neutralization reaction to obtain carbon dioxide, the purity of which is greater than 99.5%; the carbon dioxide is compressed to obtain high-pressure gas, which is introduced into the pneumatic stirring device to become the gas source of the pneumatic stirring device.

6. The system according to claim 1, characterized in that The reaction device comprises a first reaction tank, a second reaction tank, and a third reaction tank, wherein the water outlet of the first reaction tank is connected to the water inlet of the second reaction tank, and the water outlet of the second reaction tank is connected to the water inlet of the third reaction tank, and the acidity of the first reaction tank, the second reaction tank, and the third reaction tank is controlled so that H + The concentration of H in the second reaction tank is 100g / L-130g / L. + The concentration of H in the third reaction tank is 50g / L-100g / L. + The concentration is 40g / L-50g / L.

7. The system according to claim 6, characterized in that The acidic solution includes waste electrolyte, and the concentration of H2SO4 in the waste electrolyte is 100g / L-300g / L.

8. The system according to claim 1, characterized in that The limestone satisfies at least one of the following conditions: Based on the total mass of the limestone, the mass fraction of the limestone after sieving through a 200-mesh sieve is 100%; Based on the total mass of the limestone, the mass fraction of the limestone after sieving through a 300-mesh sieve is greater than or equal to 80%; Based on the total mass of the limestone, the mass fraction of calcium carbonate in the limestone is greater than or equal to 97%.

9. The system according to claim 1, characterized in that The reaction temperature of the neutralization reaction is 70°C-100°C, and the reaction time of the neutralization reaction is 3h-10h; and / or, The drying temperature of the drying treatment is 150° C.-200° C., and the drying time of the drying treatment is 3 h-10 h; and / or, The calcium sulfate dihydrate is returned to the reaction device to become the seed crystal of the neutralization reaction.

10. The system according to claim 1, characterized in that The calcium sulfate whiskers meet at least one of the following conditions: The whiteness of the calcium sulfate whiskers is 90%-99%; The mass fraction of calcium sulfate in the calcium sulfate whiskers is greater than or equal to 98%; The pH of the calcium sulfate whisker is 6.5-8.0.

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