System for circularly inducing crystallization, hardness removal and desalination of calcium sulfate in high-calcium-sulfate type wastewater

Abstract

The utility model discloses a system for calcium sulfate circulation induced crystallization, hardness removal and desalination of high calcium sulfate type wastewater, which is characterized in that a crystal inducing carrier mixing device is connected with an induced crystallization device; the crystal inducing carrier mixing device comprises a mixing tank body, and a first water outlet pipe is arranged at the top of the mixing tank body; the induced crystallization device comprises an outer cylinder; an inner cylinder, an inner circulating cylinder and a middle cylinder are coaxially arranged in the outer cylinder in sequence from inside to outside; the bottom of the inner circulating barrel is communicated with the inner end of a second water inlet pipe, the outer end of the second water inlet pipe is communicated with the first water outlet pipe, a water distributor is arranged at the bottom of the inner circulating barrel above the inner end of the second water inlet pipe, and the water distributor is positioned below the inner barrel; the side wall, located above the water distributor, of the inner circulation cylinder is communicated with the inner end of a second crystal inducing carrier adding pipe. The system disclosed by the utility model is good in softening and desalting effect, low in operation cost and small in occupied area, and high calcium sulfate type wastewater treatment technical equipment capable of realizing zero emission has a wide application prospect.

Description

Technical Field

[0001] The utility model belongs to the field of water treatment, relates to high-calcium sulfate type wastewater, and specifically relates to a system for removing hardness and desalting high-calcium sulfate type wastewater by calcium sulfate circulation induction crystallization. Background Art

[0002] The annual output of mine water in my country can reach 6.0×10 9 m 3 Of the above, 57% of the total amount is high-mineralized mine water with a total dissolved solids (TDS) greater than 1000 mg / L. Mine water with high sulfate and calcium salt content in the water is called high calcium sulfate mine water. The resource treatment of this type of water quality aims to remove hardness, sulfate and other inorganic ions in the water, and is usually treated by combining pretreatment and deep desalination. "Multi-stage membrane concentration + membrane thermal coupling desalination" is a process combination that is often used in mine water resource applications. In the treatment of this combined process, a certain amount of scale inhibitor will be added to the water before the multi-stage membrane concentration unit treatment. Under the action of the scale inhibitor and membrane concentration, the membrane concentrated water produced contains double the ion content. The ion content in this type of water quality is usually in an oversaturated state, such as Ca in the concentrated water. 2+ and SO4 2- Under the influence of scale inhibitors, the concentration of CaSO4 will be doubled to form water with supersaturated CaSO4 content. When this type of concentrated water is treated with traditional chemical precipitation methods, it usually suffers from low treatment efficiency, high chemical consumption, and high operation and maintenance costs. In actual operation, the high ion content in the water is prone to equipment clogging. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a system for the removal of hardness and salt by calcium sulfate circulation-induced crystallization of high-calcium sulfate type wastewater, so as to solve the technical problem that the treatment efficiency of the treatment system for high-calcium sulfate type wastewater in the existing technology needs to be further improved.

[0004] Another object of the present invention is to provide a system for removing hardness and salt from high-calcium sulfate type wastewater by calcium sulfate circulation-induced crystallization, so as to solve the technical problem in the prior art that the treatment economy of the treatment system for high-calcium sulfate type wastewater needs to be further improved.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A system for removing hardness and salt from high-calcium sulfate wastewater by calcium sulfate circulation induction crystallization, comprising a crystal induction carrier mixing device connected to an induction crystallization device;

[0007] The crystal-inducing carrier mixing device includes a mixing tank body, the bottom of the mixing tank body is connected to a first water inlet pipe, the side wall of the mixing tank body located above the first water inlet pipe is connected to the inner end of the first crystal-inducing carrier feeding pipe, and the top of the mixing tank body is provided with a first water outlet pipe;

[0008] The induced crystallization device includes an outer cylinder, which has a closed bottom and an open top. An inner cylinder, an inner circulation cylinder, and a middle cylinder are coaxially arranged in sequence from the inside to the outside of the outer cylinder. The top and bottom of the inner cylinder are both open. The bottom of the inner circulation cylinder is closed and the top is open. The top of the middle cylinder is closed and the bottom is open. The top of the inner cylinder is lower than the top of the inner circulation cylinder, the top of the inner circulation cylinder is lower than the top of the middle cylinder, and the top of the middle cylinder is higher than the top of the outer cylinder.

[0009] The bottom of the inner circulation drum is connected to the inner end of the second water inlet pipe, the outer end of the second water inlet pipe is connected to the first water outlet pipe, and a water distributor is provided at the bottom of the inner circulation drum above the inner end of the second water inlet pipe, and the water distributor is located below the inner drum;

[0010] The inner circulation cylinder is located on the side wall above the water distributor and is connected to the inner end of the second crystal inducing carrier feeding pipe;

[0011] A second water outlet pipe is provided on the top of the outer cylinder.

[0012] The utility model also has the following technical features:

[0013] The bottom of the outer cylinder is connected to one end of a crystal-inducing carrier discharge pipe, the other end of the crystal-inducing carrier discharge pipe is connected to a rotary drum mud-water separation device, the mud outlet end of the rotary drum mud-water separation device is connected to a crystal-inducing carrier storage barrel, and the crystal-inducing carrier storage barrel is connected to the outer end of a first crystal-inducing carrier feeding pipe through a crystal-inducing carrier conveying pump to realize wet external circulation of the crystal-inducing carrier; the crystal-inducing carrier storage barrel is connected to the outer end of a second crystal-inducing carrier feeding pipe through a screw conveyor to realize dry external circulation of the crystal-inducing carrier.

[0014] The inner circulation cylinder is a variable outer diameter structure. The outer diameter of the lower part of the inner circulation cylinder is the same as that of the inner cylinder, and the outer diameter of the upper part of the inner circulation cylinder is larger than that of the inner cylinder. The inner cylinder is located in the upper part of the inner circulation cylinder.

[0015] A mixing and stirring motor is provided on the top of the mixing tank body, and the mixing and stirring motor drives the mixing agitator located in the mixing tank body.

[0016] A top stirring motor is installed on the top of the middle cylinder, and the top stirring motor drives the upper stirrers located in the inner cylinder and the inner circulation cylinder.

[0017] A bottom stirring motor is installed at the outer bottom of the outer cylinder, and the bottom stirring motor drives a lower stirrer located at the inner bottom of the outer cylinder.

[0018] An annular water storage tank is provided on the inner wall of the top of the outer cylinder, and the annular water storage tank is connected to the second water outlet pipe.

[0019] The bottom of the inner circulation cylinder is connected with a crystal inducing carrier exhaust pipe.

[0020] The bottom of the mixing tank is provided with a first supporting base; the bottom of the outer cylinder is provided with a second supporting base.

[0021] Compared with the prior art, the present invention has the following technical effects:

[0022] (I) The system of the utility model is based on Ca in water 2+ and SO4 2- The induced crystallization is the mechanism, and the removal of Ca in water is achieved through the induction of the crystal carrier in the induced crystallization device. 2+ and SO4 2- For the purpose of this invention, compared with the known methods, the induced crystallization device in the utility model realizes the cyclic crystallization of the induced crystal carrier through structural optimization design, improves the utilization rate of the induced crystal carrier, and effectively reduces the processing cost.

[0023] (II) The system of the present invention can carry out various forms of external circulation of the crystal-inducing carrier, thus avoiding the scaling and clogging problems in the crystal-inducing device, further improving the utilization efficiency of the crystal-inducing carrier, and optimizing the continuous and stable operation effect of the system.

[0024] (III) The system of the utility model can optimize the treatment effect of high calcium sulfate wastewater of different types of water quality through different addition and reflux methods of crystal-inducing carriers, and has good adaptability to water quality.

[0025] (IV) The system of the utility model can realize the efficient softening and desalination treatment of high calcium sulfate type wastewater without adding any chemicals, thereby reducing the treatment cost and avoiding the influence of chemicals on the composition of the crystallized product. The only crystal formed during the treatment is calcium sulfate, which is effectively attached to the crystal-inducing carrier to form a high-purity gypsum product that can be recycled after dehydration, thus achieving zero emission.

[0026] (V) The system of the utility model has good softening and desalination effect, low operating cost, small footprint and can achieve "zero discharge" high calcium sulfate type wastewater treatment technology equipment and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the system for removing hardness and desalting high-calcium sulfate wastewater by calcium sulfate circulation-induced crystallization.

[0028] Figure 2 Schematic diagram of four different pathways for calcium sulfate circulation-induced crystallization desalination of high calcium sulfate wastewater.

[0029] The meanings of the numbers in the figure are: 1-crystallization-inducing carrier mixing device, 2-induced crystallization device, 3-high calcium sulfate type wastewater raw water storage tank.

[0030] 101 - mixing tank body, 102 - first water inlet pipe, 103 - first crystal-inducing carrier addition pipe, 104 - first water outlet pipe, 105 - mixing and stirring motor, 106 - mixing and stirring device, 107 - first supporting base.

[0031] 201-outer cylinder, 202-inner cylinder, 203-inner circulation cylinder, 204-middle cylinder, 205-second water inlet pipe, 206-water distributor, 207-second crystal-inducing carrier addition pipe, 208-second water outlet pipe, 209-crystal-inducing carrier discharge pipe, 210-rotary drum mud-water separation equipment, 211-crystal-inducing carrier storage barrel, 212-crystal-inducing carrier delivery pump, 213-screw conveyor, 214-top stirring motor, 215-upper agitator, 216-bottom stirring motor, 217-lower agitator, 218-annular water storage tank, 219-crystal-inducing carrier emptying pipe, 220-second support base.

[0032] The specific contents of the present invention are further explained in detail below with reference to the embodiments. DETAILED DESCRIPTION

[0033] It should be noted that, unless otherwise specified, all devices and components in the present invention are devices and components known in the prior art.

[0034] In the present invention, high calcium sulfate wastewater refers to water quality in which the calcium sulfate supersaturation is greater than 0.

[0035] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the scope of protection of the present invention.

[0036] Example 1:

[0037] This embodiment provides a system for removing hardness and salt from high calcium sulfate type wastewater by calcium sulfate circulation induction crystallization. Figure 1 As shown, it includes a crystal-inducing carrier mixing device 1, which is connected to an inducing crystallization device 2.

[0038] The crystal-inducing carrier mixing device 1 includes a mixing tank body 101, the bottom of the mixing tank body 101 is connected to a first water inlet pipe 102, the inner end of a first crystal-inducing carrier addition pipe 103 is connected to the side wall of the mixing tank body 101 above the first water inlet pipe 102, and a first water outlet pipe 104 is provided on the top of the mixing tank body 101.

[0039] The induced crystallization device 2 includes an outer cylinder 201, which has a closed bottom and an open top. An inner cylinder 202, an inner circulation cylinder 203, and a middle cylinder 204 are coaxially arranged in sequence from the inside to the outside in the outer cylinder 201. The top and bottom of the inner cylinder 202 are both open, the bottom of the inner circulation cylinder 203 is closed and the top is open, the top of the middle cylinder 204 is closed and the bottom is open, the top of the inner cylinder 202 is lower than the top of the inner circulation cylinder 203, the top of the inner circulation cylinder 203 is lower than the top of the middle cylinder 204, and the top of the middle cylinder 204 is higher than the top of the outer cylinder 201.

[0040] The bottom of the inner circulation cylinder 203 is connected to the inner end of the second water inlet pipe 205, and the outer end of the second water inlet pipe 205 is connected to the first water outlet pipe 104. A water distributor 206 is provided at the bottom of the inner circulation cylinder 203 above the inner end of the second water inlet pipe 205, and the water distributor 206 is located below the inner cylinder 202.

[0041] The inner end of the second crystal inducer carrier dosing pipe 207 is connected to the side wall of the inner circulation cylinder 203 located above the water distributor 206 .

[0042] A second water outlet pipe 208 is provided at the top of the outer cylinder 201 .

[0043] As a preferred solution of this embodiment, the bottom of the outer cylinder 201 is connected to one end of the crystal-inducing carrier discharge pipe 209, the other end of the crystal-inducing carrier discharge pipe 209 is connected to the rotary drum mud-water separation equipment 210, the mud outlet end of the rotary drum mud-water separation equipment 210 is connected to the crystal-inducing carrier storage barrel 211, the crystal-inducing carrier storage barrel 211 is connected to the outer end of the first crystal-inducing carrier addition pipe 103 through the crystal-inducing carrier conveying pump 212 to realize the wet external circulation of the crystal-inducing carrier; the crystal-inducing carrier storage barrel 211 is connected to the outer end of the second crystal-inducing carrier addition pipe 207 through the screw conveyor 213 to realize the dry external circulation of the crystal-inducing carrier.

[0044] As a preferred solution of this embodiment, the inner circulation cylinder 203 has a variable outer diameter structure, the lower outer diameter of the inner circulation cylinder 203 is the same as that of the inner cylinder 202, the upper outer diameter of the inner circulation cylinder 203 is larger than the outer diameter of the inner cylinder 202, and the inner cylinder 202 is located in the upper part of the inner circulation cylinder 203.

[0045] As a preferred solution of this embodiment, a mixing motor 105 is provided on the top of the mixing tank body 101 , and the mixing motor 105 drives a mixing agitator 106 located in the mixing tank body 101 .

[0046] As a preferred solution of this embodiment, a top stirring motor 214 is installed on the top of the middle cylinder 204, and the top stirring motor 214 drives the upper stirrer 215 located in the inner cylinder 202 and the inner circulation cylinder 203; the upper stirrer 215 is used to improve the mixing state of the raw water and the crystal-inducing carrier when the water inlet flow rate is small.

[0047] As a preferred solution of this embodiment, a bottom stirring motor 216 is installed at the outer bottom of the outer cylinder 201, and the bottom stirring motor 216 drives the lower stirrer 217 located at the inner bottom of the outer cylinder 201; the lower stirrer 217 is mainly used to prevent the crystal-inducing carrier deposited at the bottom of the outer cylinder 201 from scaling, and ensure that the crystal-inducing carrier can be smoothly discharged from the crystal-inducing carrier discharge pipe 209.

[0048] As a preferred solution of this embodiment, an annular water storage tank 218 is provided on the top inner wall of the outer cylinder 201 , and the annular water storage tank 218 is connected to the second water outlet pipe 208 .

[0049] As a preferred solution of this embodiment, the bottom of the inner circulation cylinder 203 is connected to a crystal-inducing carrier exhaust pipe 219 .

[0050] As a preferred solution of this embodiment, a first support base 107 is provided at the bottom of the mixing tank body 101 ; a second support base 220 is provided at the bottom of the outer cylinder 201 .

[0051] In this embodiment, the bottom of the outer cylinder 201 is a conical structure or an arc-shaped structure; the bottom of the inner circulation cylinder 203 is a conical structure or an arc-shaped structure.

[0052] In this embodiment, the inner cylinder 202, the inner circulation cylinder 203, the middle cylinder 204 and the outer cylinder 201 are all connected and fixed by ribs.

[0053] In this embodiment, valves and flow meters are provided in the auxiliary pipelines of the crystal-inducing carrier mixing device 1 and the crystal-inducing device 2 as needed.

[0054] When the system of this embodiment is in use, the raw water of high calcium sulfate type wastewater and the crystal-inducing carrier enter the mixing tank 201 and are evenly mixed with water through stirring, and the formed mixed liquid flows out from the first outlet pipe 104 at the top.

[0055] The mixed liquid enters the inner circulation tube 203 through the second water inlet pipe 205 and is evenly distributed through the water distributor 206. Then, the mixed liquid enters the inner tube 202 from the bottom to induce crystallization reaction. The Ca in the raw water of high calcium sulfate type wastewater is reduced. 2+ and SO4 2- Under the induction of the crystal-inducing carrier, a chemical reaction quickly occurs to generate CaSO4 microcrystals which adhere to the surface of the crystal-inducing carrier, thus achieving the purpose of softening and desalination.

[0056] The mixed liquid formed by the reacted water and the crystal-inducing carrier rises to the top of the inner cylinder 202, and then a part of the carrier with larger particle size sinks into the inner circulation cylinder 203 to form an internal circulation of the crystal-inducing carrier. The other part of the particles with smaller particle size rises with the water flow to the top of the inner cylinder 202 and then enters the middle cylinder 204 to continue the solid-liquid separation process. The liquid after solid-liquid separation rises from the bottom of the outer cylinder 201 to the annular water storage tank 218 at the top for convergence, and then flows out of the induced crystallization device 2 through the second water outlet pipe 208.

[0057] After solid-liquid separation, the crystallization carrier is deposited at the bottom of the outer cylinder 201 and discharged through the crystallization carrier discharge pipe 209 for external circulation. This external circulation is divided into dry and wet types. The crystallization carrier enters the crystallization device 2 through the dry type, while the crystallization carrier enters the crystallization carrier mixing device 1 through the wet type.

[0058] Example 2:

[0059] This embodiment provides a method for removing hardness and salt from high-calcium sulfate type wastewater by calcium sulfate circulation-induced crystallization. The method adopts the system for removing hardness and salt from high-calcium sulfate type wastewater provided in Example 1 by calcium sulfate circulation-induced crystallization.

[0060] In this embodiment, the calcium sulfate circulation-induced crystallization desalination system can flexibly adjust the system operating conditions to form different process paths according to the water quality of the raw water to be treated, the treatment requirements, and the land requirements.

[0061] like Figure 2 As shown, the method includes the following four paths:

[0062] Path one: the raw water of high calcium sulfate type wastewater directly enters the induced crystallization device 2 for treatment. Before the induced crystallization device 2 starts to operate, all the crystal-inducing carriers are added to the inner circulation drum 203. During the operation, the crystal-inducing carriers are directly refluxed without passing through the crystal-inducing carrier mixing device 1 when they are circulated externally.

[0063] Path two, the raw water of high calcium sulfate type wastewater directly enters the induced crystallization device 2 for treatment. Before the induced crystallization device 2 starts to operate, all the crystal-inducing carriers are added to the inner circulation drum 203. During the operation, the crystal-inducing carriers are first discharged into the crystal-inducing carrier mixing device 1 when they circulate externally, and then reflux after being evenly mixed with the raw water.

[0064] Path three, the raw water of high calcium sulfate type wastewater first enters the crystal-inducing carrier mixing device 1 to be mixed with the crystal-inducing carrier, and after being evenly mixed, it enters the crystal-inducing device 2 for continuous operation. During the operation, the crystal-inducing carrier circulates externally without passing through the crystal-inducing carrier mixing device 1 and directly refluxes.

[0065] Path four, the raw water of high calcium sulfate type wastewater first enters the crystal-inducing carrier mixing device 1 to be mixed with the crystal-inducing carrier, and then enters the crystal-inducing carrier 2 for continuous operation after being evenly mixed. During the operation, the crystal-inducing carrier is first discharged into the crystal-inducing carrier mixing device 1 when it is circulated externally, and then refluxed after being evenly mixed with the raw water.

[0066] Path 1 is applicable to high calcium sulfate type wastewater with calcium sulfate supersaturation greater than or equal to 1.2, and Ca 2+ Content greater than or equal to 1800mg / L, SO4 2- Desalination and hardness removal of water with a content greater than or equal to 14000mg / L.

[0067] Path 2 is applicable to high calcium sulfate type wastewater with calcium sulfate supersaturation greater than 0.9 and less than 1.2, and Ca 2+ Content greater than 1500 mg / L and less than 1800 mg / L, SO4 2- Desalination and hardness removal of water with a content greater than 11000mg / L and less than 14000mg / L.

[0068] Path 3 is applicable to high calcium sulfate type wastewater with calcium sulfate supersaturation greater than 0.6 and less than or equal to 0.9 in the raw water, and Ca 2+ Content greater than 1200 mg / L and less than or equal to 1500 mg / L, SO4 2- Desalination and hardness removal of water with a content greater than 8000mg / L and less than or equal to 11000mg / L.

[0069] Path 4 is applicable to high calcium sulfate type wastewater with calcium sulfate supersaturation less than or equal to 0.6 in the raw water, and Ca 2+ Content is less than or equal to 1200mg / L, SO4 2- De-hardening and desalination treatment of water with a content of less than or equal to 8000mg / L.

[0070] Specifically, in this embodiment, the raw water of high calcium sulfate type wastewater has Ca 2+ The content is 1430mg / L, SO4 2- The content is 10013mg / L. After simulating and calculating the raw water of high calcium sulfate wastewater, its supersaturation index ( SI ) is 0.62, which determines that the raw water has a low supersaturation index and high ion content, and is treated using Path 3.

[0071] Specifically, in this embodiment, the crystal-inducing carrier is industrial-grade gypsum crystal particles.

[0072] Specifically in this embodiment, the water inlet flow rate of the induced crystallization device 2 is controlled to be 1m 3 / h, the speed of the upper agitator 215 is controlled at 9r / min, and the speed of the lower agitator 217 is controlled at 4r / min. During the continuous and stable operation of the system, the crystal-inducing carrier at the bottom of the outer cylinder 201 is connected to the outer end of the first crystal-inducing carrier addition pipe 103 through the crystal-inducing carrier delivery pump 212 to realize the wet external circulation of the crystal-inducing carrier, and then flows back to the crystal-inducing carrier mixing device 1 to mix with the raw water and then reflux.

[0073] Specifically in this embodiment, during the continuous and stable operation of the system, Ca 2+ The removal rate can reach 45%~53%.

Claims

1. A system for removing hardness and salt from high calcium sulfate type wastewater by calcium sulfate circulation induced crystallization, characterized in that: The invention comprises a crystal-inducing carrier mixing device (1), wherein the crystal-inducing carrier mixing device (1) is connected to an inducing crystallization device (2); The crystal-inducing carrier mixing device (1) comprises a mixing tank body (101), the bottom of the mixing tank body (101) is connected to a first water inlet pipe (102), the side wall of the mixing tank body (101) above the first water inlet pipe (102) is connected to the inner end of a first crystal-inducing carrier dosing pipe (103), and the top of the mixing tank body (101) is provided with a first water outlet pipe (104); The induced crystallization device (2) includes an outer cylinder (201), the bottom of the outer cylinder (201) is closed and the top is open, the inner cylinder (202), the inner circulation cylinder (203), and the middle cylinder (204) are coaxially arranged in sequence from the inside to the outside of the outer cylinder (201), the top and bottom of the inner cylinder (202) are both open, the bottom of the inner circulation cylinder (203) is closed and the top is open, the top of the middle cylinder (204) is closed and the bottom is open, the top of the inner cylinder (202) is lower than the top of the inner circulation cylinder (203), the top of the inner circulation cylinder (203) is lower than the top of the middle cylinder (204), and the top of the middle cylinder (204) is higher than the top of the outer cylinder (201); The bottom of the inner circulation cylinder (203) is connected to the inner end of the second water inlet pipe (205), the outer end of the second water inlet pipe (205) is connected to the first water outlet pipe (104), and a water distributor (206) is provided at the bottom of the inner circulation cylinder (203) above the inner end of the second water inlet pipe (205), and the water distributor (206) is located below the inner cylinder (202); The inner circulation cylinder (203) is located on a side wall above the water distributor (206) and is connected to the inner end of the second crystal-inducing carrier dosing pipe (207); A second water outlet pipe (208) is provided at the top of the outer cylinder (201).

2. The system for calcium sulfate circulation induced crystallization and desalination of high calcium sulfate type wastewater as claimed in claim 1, wherein the bottom of the outer cylinder (201) is connected to one end of the crystal inducing carrier discharge pipe (209), the other end of the crystal inducing carrier discharge pipe (209) is connected to the rotary drum mud and water separation equipment (210), the mud outlet end of the rotary drum mud and water separation equipment (210) is connected to the crystal inducing carrier storage barrel (211), the crystal inducing carrier storage barrel (211) is connected to the outer end of the first crystal inducing carrier feeding pipe (103) through the crystal inducing carrier conveying pump (212) to realize the wet external circulation of the crystal inducing carrier; the crystal inducing carrier storage barrel (211) is connected to the outer end of the second crystal inducing carrier feeding pipe (207) through the screw conveyor (213) to realize the dry external circulation of the crystal inducing carrier.

3. The system for removing hardness and salt from high-calcium sulfate type wastewater by calcium sulfate circulation-induced crystallization as described in claim 1, wherein the inner circulation cylinder (203) is a variable outer diameter structure, the lower outer diameter of the inner circulation cylinder (203) is the same as that of the inner cylinder (202), the upper outer diameter of the inner circulation cylinder (203) is larger than the outer diameter of the inner cylinder (202), and the inner cylinder (202) is located in the upper part of the inner circulation cylinder (203).

4. The system for removing hardness and salt from high-calcium sulfate type wastewater by calcium sulfate circulation-induced crystallization as claimed in claim 1, wherein a mixing motor (105) is provided on the top of the mixing tank (101), and the mixing motor (105) drives a mixing agitator (106) located in the mixing tank (101).

5. The system for removing hardness and salt from high-calcium sulfate type wastewater by calcium sulfate circulation-induced crystallization as claimed in claim 1, wherein a top stirring motor (214) is installed on the top of the middle cylinder (204), and the top stirring motor (214) drives the upper stirrer (215) located in the inner cylinder (202) and the inner circulation cylinder (203).

6. The system for removing hardness and salt from high-calcium sulfate type wastewater by calcium sulfate circulation-induced crystallization as claimed in claim 1, wherein a bottom stirring motor (216) is installed at the outer bottom of the outer cylinder (201), and the bottom stirring motor (216) drives a lower stirrer (217) located at the inner bottom of the outer cylinder (201).

7. The system for removing hardness and salt from high-calcium sulfate type wastewater by calcium sulfate circulation-induced crystallization as claimed in claim 1, wherein an annular water storage tank (218) is provided on the top inner wall of the outer cylinder (201), and the annular water storage tank (218) is connected to the second water outlet pipe (208).

8. The system for removing hardness and salt by calcium sulfate circulation-induced crystallization of high-calcium sulfate type wastewater as claimed in claim 1, wherein the bottom of the inner circulation cylinder (203) is connected to a crystal-inducing carrier emptying pipe (219).

9. The system for removing hardness and salt from high-calcium sulfate type wastewater by calcium sulfate circulation-induced crystallization as claimed in claim 1, wherein a first support base (107) is provided at the bottom of the mixing tank (101); and a second support base (220) is provided at the bottom of the outer cylinder (201).

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