A three-stage countercurrent water washing process and device for calcium carbonate based on gypsum conversion

Abstract

The present invention relates to a three-stage countercurrent water washing process and device for calcium carbonate based on gypsum conversion, including an automatic feeding centrifuge, a washing liquid pump, a water washing tank group, an upper water pipe, a lower water pipe, and a centrifuge stand; the automatic feeding centrifuge is located directly above the water washing tank group, the automatic feeding centrifuge is fixed by the centrifuge stand, the outlet of the automatic feeding centrifuge is connected to the inlet of the water washing tank group through the lower water pipe, and the outlet of the water washing tank group is connected to the inlet of the automatic feeding centrifuge through the washing liquid pump and the upper water pipe; the water washing tank group includes a first-stage washing liquid tank, a second-stage washing liquid tank, a third-stage washing liquid tank, a clear water tank, and a solid material tank, and the first-stage washing liquid tank, the second-stage washing liquid tank, the third-stage washing liquid tank, and the clear water tank are all annular columnar structures. The beneficial effects of the present invention are as follows: the water washing tank group of the present invention adopts an annular structure, and the automatic feeding centrifuge is located directly above the water washing tank group. The equipment structure is reasonable, the layout is compact, and the problems of washing water consumption and equipment floor area in the washing process are better solved.

Description

Technical Field

[0001] The present invention relates to a process for washing calcium carbonate solids, and particularly to a process for washing calcium carbonate solids as reaction products based on gypsum conversion. Background Art

[0002] Industrial by-product gypsum can react with other chemical substances (such as ammonium carbonate, sodium carbonate, ammonium bicarbonate, etc.) to form calcium carbonate and another compound, which is generally soluble. Therefore, the reaction mixture needs to be filtered to separate the products. The separated solid calcium carbonate will contain a certain amount of moisture, and this compound (such as ammonium sulfate, sodium sulfate, etc.) will be dissolved in the moisture. Therefore, to avoid other impurity components in calcium carbonate, it needs to be washed. The washing liquid after washing will flow into the separation liquid. To reduce the subsequent water treatment cost, the lower the amount of washing liquid used, the more beneficial it is. The conventional washing method is to directly wash the solid with clear water and perform multiple washes until the content of other components in the solid is reduced to a certain level. However, the disadvantage of this method is that the amount of washing water used is large, increasing the subsequent water treatment cost. The multi-stage washing method can reduce the amount of water used for washing, but the system is complex and occupies a large area. Summary of the Invention

[0003] The object of the present invention is to overcome the deficiencies in the prior art and provide a three-stage countercurrent water washing process and device for calcium carbonate based on gypsum conversion that can reduce the amount of washing water used and the equipment footprint at the same time. This process and device can be used for washing calcium carbonate. Similarly, this process and device can also be used for washing when other insoluble solids and soluble substances are mixed.

[0004] This three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion includes an automatic feeding centrifuge, a washing liquid pump, a water washing tank group, an upper water pipe, a lower water pipe, and a centrifuge stand. The automatic feeding centrifuge is located directly above the water washing tank group and is fixed by the centrifuge stand. The outlet of the automatic feeding centrifuge is connected to the inlet of the water washing tank group through the lower water pipe, and the outlet of the water washing tank group is connected to the inlet of the automatic feeding centrifuge through the washing liquid pump and the upper water pipe. The water washing tank group includes a first-stage washing liquid tank, a second-stage washing liquid tank, a third-stage washing liquid tank, a clear water tank, and a solid material tank. The first-stage washing liquid tank, the second-stage washing liquid tank, the third-stage washing liquid tank, and the clear water tank are all circular ring-shaped columns and are arranged in a 3 / 4 circular ring shape. The solid material tank is placed in the circular hole at the center of the circular ring. Liquid inlet pipelines are provided at the upper parts of the side walls of the first-stage washing liquid tank, the second-stage washing liquid tank, and the third-stage washing liquid tank, and liquid inlet valves are respectively equipped. The liquid inlet pipelines are connected to the lower water pipe. Liquid outlet pipelines are provided at the lower parts of the side walls of the second-stage washing liquid tank, the third-stage washing liquid tank, and the clear water tank, and liquid outlet valves are respectively equipped. After the liquid outlet pipelines are aggregated, they are connected to the washing liquid pump.

[0005] Preferably: The feeding port of the automatic feeding centrifuge corresponds to the solid material tank of the water washing tank group.

[0006] Preferably, the liquid inlet pipeline is annular, and is provided with liquid inlet pipeline branches respectively connected to the primary washing liquid tank, the secondary washing liquid tank and the tertiary washing liquid tank. The liquid inlet pipeline branches corresponding to the primary washing liquid tank, the secondary washing liquid tank and the tertiary washing liquid tank are respectively equipped with a primary washing liquid tank liquid inlet valve, a secondary washing liquid tank liquid inlet valve and a tertiary washing liquid tank liquid inlet valve.

[0007] Preferably, the liquid outlet pipeline is annular, and is provided with liquid outlet pipeline branches respectively connected to the secondary washing liquid tank, the tertiary washing liquid tank and the clean water tank. The liquid outlet pipeline branches corresponding to the secondary washing liquid tank, the tertiary washing liquid tank and the clean water tank are respectively equipped with a secondary washing liquid tank liquid outlet valve, a tertiary washing liquid tank liquid outlet valve and a clean water tank liquid outlet valve.

[0008] Preferably, a drain valve is provided at the drain outlet at the bottom of the primary washing liquid tank, and a water replenishing valve is provided at the water inlet at the top of the clean water tank.

[0009] Preferably, the lower part of the centrifuge stand is of a hollow structure, and a water washing tank group is placed in the hollow structure.

[0010] The water washing process of this three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion includes the following steps:

[0011] S1. The calcium carbonate suspension enters the automatic feeding centrifuge for the first solid-liquid separation. After working for 1 - 10 minutes at a rotation speed of 800 - 1500 r / min, the calcium carbonate solid remains on the separation equipment, the soluble substances dissolve in the washing liquid, the primary washing liquid tank liquid inlet valve is opened, and other valves are closed. The separated liquid enters the primary washing liquid tank;

[0012] S2. The secondary washing liquid tank liquid outlet valve is opened, other valves are closed, the washing liquid pump is started, and after running for a certain time, the washing liquid pump is closed. A certain amount of liquid is pumped from the secondary washing liquid tank into the centrifuge, and the centrifuge is kept rotating at 300 - 1000 r / min. At this time, the washing liquid nozzles of the centrifuge evenly spray the washing liquid on the solid filter layer, and then solid-liquid separation is carried out under the same conditions as in step S1. The calcium carbonate solid powder remains on the separation equipment, the soluble substances dissolve in the washing liquid, other valves are closed, the primary washing liquid tank liquid inlet valve is opened, and the separated liquid enters the primary washing liquid tank;

[0013] S3. The tertiary washing liquid tank liquid outlet valve is opened, other valves are closed, the washing liquid pump is started, and after running for a certain time, the washing liquid pump is closed. The same amount of liquid as in step S2 is pumped from the tertiary washing liquid tank into the centrifuge, and the centrifuge is kept rotating at 300 - 1000 r / min. At this time, the washing liquid nozzles of the centrifuge evenly spray the washing liquid on the solid filter layer, and then solid-liquid separation is carried out under the same conditions as in step S1. The calcium carbonate solid powder remains on the separation equipment, the soluble substances dissolve in the washing liquid, the secondary washing liquid tank liquid inlet valve is opened, other valves are closed, and the separated liquid enters the secondary washing liquid tank;

[0014] S4. Open the liquid outlet valve of the clean water tank, close other valves, turn on the washing liquid pump, run for a certain period of time and then turn off the washing liquid pump. Extract the same amount of liquid as in step S2 from the clean water tank into the centrifuge, keep the centrifuge rotating at 300 - 1000 r / min. At this time, the washing liquid spray head of the centrifuge evenly sprays the washing liquid on the solid filter layer, and then perform solid-liquid separation under the same conditions as in step S1. The calcium carbonate solid powder remains on the separation device, and the easily soluble substances dissolve in the washing liquid. Open the liquid inlet valve of the third-stage washing liquid tank, close other valves, and the separated liquid enters the third-stage washing liquid tank.

[0015] Preferably, when the first-stage washing liquid tank in step S2 is full of water, the liquid is discharged from the drain valve; when the water volume in the clean water tank in step S4 is insufficient, water is fed in from the water replenishing valve.

[0016] Preferably, the washing liquid pump in steps S2 - S4 and each valve in steps S1 - S4 are automatically set for the start-stop sequence by the control system.

[0017] Preferably, each valve in steps S1 - S4 adopts a pneumatic valve.

[0018] The beneficial effects of the present invention are as follows: The washing water tank group of the present invention adopts an annular structure, and the automatic feeding centrifuge is located directly above the washing water tank group. The equipment structure is reasonable and the layout is compact, which better solves the problems of washing water consumption and equipment floor area during the washing process; and it adopts automatic control, greatly improving the working efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the front view of the device structure of the present invention;

[0020] Figure 2 It is the top view of the liquid inlet pipeline layer of the washing water tank group;

[0021] Figure 3 It is the top view of the liquid outlet pipeline layer of the washing water tank group.

[0022] Explanation of reference numerals in the drawings: Automatic feeding centrifuge 1, Washing liquid pump 2, Washing water tank group 3, Water supply pipe 4, Water discharge pipe 5, Centrifuge stand 6, First-stage washing liquid tank 7, Second-stage washing liquid tank 8, Third-stage washing liquid tank 9, Clean water tank 10, Solid material tank 11, First-stage washing liquid tank liquid inlet valve 12, Second-stage washing liquid tank liquid inlet valve 13, Third-stage washing liquid tank liquid inlet valve 14, Second-stage washing liquid tank liquid outlet valve 15, Third-stage washing liquid tank liquid outlet valve 16, Clean water tank liquid outlet valve 17, Drain valve 18, Water replenishing valve 19. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will be further described below in conjunction with embodiments. The description of the following embodiments is only for helping to understand the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0024] Embodiment 1

[0025] This embodiment provides a three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion, which includes an automatic feeding centrifuge 1, a washing liquid pump 2, a water washing tank group 3, a water supply pipe 4, a water discharge pipe 5, and a centrifuge stand 6. The automatic feeding centrifuge 1 is located directly above the water washing tank group 3, and the automatic feeding centrifuge 1 is fixed by the centrifuge stand 6. The outlet of the automatic feeding centrifuge 1 is connected to the inlet of the water washing tank group 3 through the water discharge pipe 5, and the outlet of the water washing tank group 3 is connected to the inlet of the automatic feeding centrifuge 1 through the washing liquid pump 2 and the water supply pipe 4. The separated liquid enters the water washing tank group 3 from the automatic feeding centrifuge 1 through the water discharge pipe 5 by gravity, and then the liquid is pumped back to the automatic feeding centrifuge 1 through the water supply pipe 4 by the washing liquid pump 2. The water washing tank group 3 includes a first-stage washing liquid tank 7, a second-stage washing liquid tank 8, a third-stage washing liquid tank 9, a clear water tank 10, and a solid material tank 11. The first-stage washing liquid tank 7, the second-stage washing liquid tank 8, the third-stage washing liquid tank 9, and the clear water tank 10 are all designed in the shape of an annular cylinder and are closely arranged in a 3 / 4 circular ring shape. A solid material tank 11 is placed in the circular hole at the center of the circular ring shape for receiving the solid material falling from the centrifuge, and its layout form is as Figure 2 , 3 shown. Liquid inlet pipes are provided at the upper parts of the side walls of the first-stage washing liquid tank 7, the second-stage washing liquid tank 8, and the third-stage washing liquid tank 9, and liquid inlet valves are respectively equipped. The liquid inlet pipes are connected to the water discharge pipe 5 for collecting the liquid generated during the water washing process. Liquid outlet pipes are provided at the lower parts of the side walls of the second-stage washing liquid tank 8, the third-stage washing liquid tank 9, and the clear water tank 10, and liquid outlet valves are respectively equipped. After the liquid outlet pipes are aggregated, they are connected to the washing liquid pump 2 and are pumped back to the centrifuge as solid washing liquid through the washing liquid pump 2.

[0026] As a preferred embodiment, for the automatic feeding centrifuge 1, the solid is fed into the water washing tank group from the hollow position below the centrifuge, and the liquid enters the water washing tank group from the side water discharge pipe 5. The feeding port of the automatic feeding centrifuge 1 corresponds to the solid material tank 11 of the water washing tank group.

[0027] As a preferred embodiment, the liquid inlet pipes are in a circular ring shape, and multiple liquid inlet pipe branches are provided and respectively connected to the first-stage washing liquid tank 7, the second-stage washing liquid tank 8, and the third-stage washing liquid tank 9. A first-stage washing liquid tank liquid inlet valve 12, a second-stage washing liquid tank liquid inlet valve 13, and a third-stage washing liquid tank liquid inlet valve 14 are respectively equipped on the liquid inlet pipe branches corresponding to the first-stage washing liquid tank 7, the second-stage washing liquid tank 8, and the third-stage washing liquid tank 9.

[0028] As a preferred embodiment, the liquid outlet pipeline is circular, and is provided with a plurality of liquid outlet pipeline branches respectively connected to the secondary washing liquid tank 8, the tertiary washing liquid tank 9 and the clean water tank 10. Secondary washing liquid tank outlet valves 15, tertiary washing liquid tank outlet valves 16 and clean water tank outlet valves 17 are respectively equipped on the liquid outlet pipeline branches corresponding to the secondary washing liquid tank 8, the tertiary washing liquid tank 9 and the clean water tank 10. After the washing liquid pipelines are aggregated, they are pumped back to the centrifuge through the washing liquid pump 2 as solid washing liquid.

[0029] As a preferred embodiment, a drain valve 18 is provided at the drain outlet at the bottom of the primary washing liquid tank 7, and a water replenishing valve 19 is provided at the water inlet at the top of the clean water tank 10.

[0030] As a preferred embodiment, the centrifuge stand 6 is mainly used to fix the centrifuge. The lower part of the centrifuge stand 6 is a hollow structure to facilitate the placement of the water washing tank group 3.

[0031] Embodiment 2

[0032] This embodiment provides a process for water washing using a three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion, including the following steps:

[0033] S1. The calcium carbonate suspension enters the automatic feeding centrifuge 1 for the first solid-liquid separation. After working for 1 - 10 minutes at a rotational speed of 800 - 1500 r / min, the calcium carbonate solid remains on the separation equipment, and the easily soluble substances dissolve in the washing liquid. The primary washing liquid tank inlet valve 12 is opened, and other valves are closed. The separated liquid (the liquid separated from the solid-liquid) enters the primary washing liquid tank 7.

[0034] S2. The secondary washing liquid tank outlet valve 15 is opened, and other valves are closed. The washing liquid pump 2 is started and runs for a certain time and then is closed. A certain amount of liquid is extracted from the secondary washing liquid tank 8 and enters the centrifuge. The centrifuge is kept rotating at a high speed of 300 - 1000 r / min. At this time, the washing liquid nozzles of the centrifuge evenly spray the washing liquid on the solid filter layer, and then solid-liquid separation is carried out under the same conditions as in step S1. The calcium carbonate solid powder remains on the separation equipment, and the easily soluble substances dissolve in the washing liquid. Other valves are closed, and the primary washing liquid tank inlet valve 12 is opened. The separated liquid enters the primary washing liquid tank 7.

[0035] S3. The tertiary washing liquid tank outlet valve 16 is opened, and other valves are closed. The washing liquid pump 2 is started and runs for a certain time and then is closed. The same amount of liquid as in step S2 is extracted from the tertiary washing liquid tank 9 and enters the centrifuge. The centrifuge is kept rotating at a high speed of 300 - 1000 r / min. At this time, the washing liquid nozzles of the centrifuge evenly spray the washing liquid on the solid filter layer, and then solid-liquid separation is carried out under the same conditions as in step S1. The calcium carbonate solid powder remains on the separation equipment, and the easily soluble substances dissolve in the washing liquid. The secondary washing liquid tank inlet valve 13 is opened, and other valves are closed. The separated liquid enters the secondary washing liquid tank 8.

[0036] S4. Open the liquid outlet valve 17 of the clean water tank, close other valves, turn on the washing liquid pump 2, run for a certain period of time and then turn off the washing liquid pump 2. Draw the same amount of liquid as in step S2 from the clean water tank 10 into the centrifuge, and keep the centrifuge rotating at a high speed of 300 - 1000 r / min. At this time, the washing liquid spray head of the centrifuge evenly sprays the washing liquid on the solid filter layer, and then perform solid-liquid separation under the same conditions as in step S1. The calcium carbonate solid powder remains on the separation device, and the easily soluble substances dissolve in the washing liquid. Open the liquid inlet valve 14 of the tertiary washing liquid tank, close other valves, and the separated liquid enters the tertiary washing liquid tank 9.

[0037] As a preferred embodiment, when each step is run for the first time, there is initial clean water in the primary washing liquid tank 7, secondary washing liquid tank 8, tertiary washing liquid tank 9 and clean water tank 10. During operation, both the secondary washing liquid tank 8 and the tertiary washing liquid tank 9 have both water inlet and outlet to form a water washing cycle. After running multiple times, when the primary washing liquid tank 7 is full of water, the liquid is discharged from the drain valve 18. When the water volume in the clean water tank 10 is insufficient, water is inlet from the water replenishing valve 19.

[0038] As a preferred embodiment, in each step, the solid-liquid separation device adopts an automatic discharging centrifuge. Compared with other solid-liquid separation devices, the centrifuge can obtain a lower water content of the calcium carbonate solid, and the automatic discharging improves the working intensity.

[0039] As a preferred embodiment, to achieve automated continuous operation, in each step, the washing liquid pump and each valve are automatically set for the on-off start-stop sequence by the control system.

[0040] As a preferred embodiment, the valves adopted in each step are preferably but not limited to pneumatic valves.

[0041] In each step, since the process conditions of the centrifuge equipment and the calcium carbonate solid substance remain unchanged, the residual water content in the calcium carbonate remains unchanged after each filtration, and the residual mass remains unchanged; and each stage of the washing liquid has the same mass, so the mass of the washing liquid discharged at each stage is the same and is consistent with the mass of the inhaled washing liquid, that is, a certain amount of clean water performs three-stage countercurrent washing on the calcium carbonate solid, and finally an equal amount of washed liquid is discharged.

[0042] Example Three

[0043] This example provides a three-stage countercurrent water washing process for calcium carbonate based on gypsum conversion, including the following steps:

[0044] S1. A mixture of 30 kg of calcium carbonate, 20 kg of ammonium sulfate and 50 kg of water suspension first enters the centrifuge and works at a speed of 1500 r / min for 3 min. 30 kg of calcium carbonate solid adsorbs on the centrifuge wall. At this time, the solid contains 2.5 kg of water and 1 kg of ammonium sulfate.

[0045] S2. Then, pump in 10 kg of secondary wash liquid through a water pump. This wash liquid contains approximately 0.311 kg of ammonium sulfate and 9.689 kg of water. After the first water wash, 30 kg of calcium carbonate solid adheres to the centrifuge wall. At this time, the solid contains 3.160 kg of water and 0.340 kg of ammonium sulfate.

[0046] S3. At this time, pump in 10 kg of tertiary wash liquid through a water pump. This wash liquid contains approximately 0.081 kg of ammonium sulfate and 9.919 kg of water. After the second water wash, 30 kg of calcium carbonate solid adheres to the centrifuge wall. At this time, the solid contains 3.371 kg of water and 0.109 kg of ammonium sulfate.

[0047] S4. At this time, pump in 10 kg of clean water through a water pump. The clean water contains 0 kg of ammonium sulfate and 10 kg of water. After the third water wash, 30 kg of calcium carbonate solid adheres to the centrifuge wall. At this time, the solid contains 3.467 kg of water and 0.028 kg of ammonium sulfate.

[0048] After three-stage countercurrent washing, 10 kg of clean water achieves a cleaning efficiency of approximately 97.2%. Under the same cleaning efficiency, single washing requires 125 kg of water, and three-stage countercurrent washing can save 92% of water.

Claims

1. A three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion, characterized in that: It includes an automatic feeding centrifuge (1), a washing liquid pump (2), a water washing tank group (3), an upper water pipe (4), a lower water pipe (5) and a centrifuge stand (6); the automatic feeding centrifuge (1) is located directly above the water washing tank group (3), the automatic feeding centrifuge (1) is fixed by the centrifuge stand (6), the outlet of the automatic feeding centrifuge (1) is connected to the inlet of the water washing tank group (3) through the lower water pipe (5), and the outlet of the water washing tank group (3) is connected to the inlet of the automatic feeding centrifuge (1) through the washing liquid pump (2) and the upper water pipe (4); the water washing tank group (3) includes a primary washing liquid tank (7), a secondary washing liquid tank (8), a tertiary washing liquid tank (9), a clean water tank (10) and a solid material tank (11), the primary washing liquid tank (7), the secondary washing liquid tank (8), the tertiary washing liquid tank (9) and the clean water tank (10) are all circular columnar structures and are arranged in a 3 / 4 circular ring shape, and the solid material tank (11) is placed in the circular hole at the center of the circular ring; the upper parts of the side walls of the primary washing liquid tank (7), the secondary washing liquid tank (8) and the tertiary washing liquid tank (9) are all provided with liquid inlet pipelines and are respectively equipped with liquid inlet valves, and the liquid inlet pipelines are connected to the lower water pipe (5); the lower parts of the side walls of the secondary washing liquid tank (8), the tertiary washing liquid tank (9) and the clean water tank (10) are all provided with liquid outlet pipelines and are respectively equipped with liquid outlet valves, and after the liquid outlet pipelines are aggregated, they are connected to the washing liquid pump (2); the feeding port of the automatic feeding centrifuge (1) corresponds to the solid material tank (11) of the water washing tank group; the liquid inlet pipeline is circular, and there are liquid inlet pipeline branches respectively connected to the primary washing liquid tank (7), the secondary washing liquid tank (8) and the tertiary washing liquid tank (9), and the primary washing liquid tank inlet valve (12), the secondary washing liquid tank inlet valve (13) and the tertiary washing liquid tank inlet valve (14) are respectively equipped on the corresponding liquid inlet pipeline branches of the primary washing liquid tank (7), the secondary washing liquid tank (8) and the tertiary washing liquid tank (9).

2. The three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion according to claim 1, characterized in that: The liquid outlet pipeline is circular, and there are liquid outlet pipeline branches respectively connected to the secondary washing liquid tank (8), the tertiary washing liquid tank (9) and the clean water tank (10), and the secondary washing liquid tank outlet valve (15), the tertiary washing liquid tank outlet valve (16) and the clean water tank outlet valve (17) are respectively equipped on the corresponding liquid outlet pipeline branches of the secondary washing liquid tank (8), the tertiary washing liquid tank (9) and the clean water tank (10).

3. The three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion according to claim 1, characterized in that: A drain valve (18) is provided at the drain outlet at the bottom of the primary washing liquid tank (7), and a water replenishing valve (19) is provided at the water inlet at the top of the clean water tank (10).

4. The three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion according to claim 1, characterized in that: The lower part of the centrifuge stand (6) is a hollow structure, and the water washing tank group (3) is placed in the hollow structure.

5. A water washing process for a three-stage countercurrent water washing device of calcium carbonate based on gypsum conversion as described in claim 1, characterized in that, It includes the following steps: S1. The calcium carbonate suspension enters the automatic feeding centrifuge (1) for the first solid-liquid separation. After working for 1 - 10 minutes at a rotation speed of 800 - 1500 r / min, the calcium carbonate solid remains on the separation device, the easily soluble substances dissolve in the washing liquid, the primary washing liquid tank inlet valve (12) is opened, and other valves are closed, and the separated liquid enters the primary washing liquid tank (7). S2. Open the liquid outlet valve (15) of the secondary washing liquid tank, close other valves, start the washing liquid pump (2), run for a certain period of time and then turn off the washing liquid pump (2). Extract a certain amount of liquid from the secondary washing liquid tank (8) into the centrifuge, and keep the centrifuge rotating at 300 - 1000 r / min. At this time, the washing liquid spray head of the centrifuge evenly sprays the washing liquid on the solid filter layer, and then perform solid-liquid separation under the same conditions as in step S1. The calcium carbonate solid powder remains on the separation equipment, the soluble substances dissolve in the washing liquid, close other valves, open the liquid inlet valve (12) of the primary washing liquid tank, and the separated liquid enters the primary washing liquid tank (7); S3. Open the liquid outlet valve (16) of the tertiary washing liquid tank, close other valves, start the washing liquid pump (2), run for a certain period of time and then turn off the washing liquid pump (2). Extract the same amount of liquid as in step S2 from the tertiary washing liquid tank (9) into the centrifuge, and keep the centrifuge rotating at 300 - 1000 r / min. At this time, the washing liquid spray head of the centrifuge evenly sprays the washing liquid on the solid filter layer, and then perform solid-liquid separation under the same conditions as in step S1. The calcium carbonate solid powder remains on the separation equipment, the soluble substances dissolve in the washing liquid, open the liquid inlet valve (13) of the secondary washing liquid tank, close other valves, and the separated liquid enters the secondary washing liquid tank (8); S4. Open the liquid outlet valve (17) of the clean water tank, close other valves, start the washing liquid pump (2), run for a certain period of time and then turn off the washing liquid pump (2). Extract the same amount of liquid as in step S2 from the clean water tank (10) into the centrifuge, and keep the centrifuge rotating at 300 - 1000 r / min. At this time, the washing liquid spray head of the centrifuge evenly sprays the washing liquid on the solid filter layer, and then perform solid-liquid separation under the same conditions as in step S1. The calcium carbonate solid powder remains on the separation equipment, the soluble substances dissolve in the washing liquid, open the liquid inlet valve (14) of the tertiary washing liquid tank, close other valves, and the separated liquid enters the tertiary washing liquid tank (9).

6. The water washing process of the three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion according to claim 5, characterized in that: When the primary washing liquid tank (7) is full in step S2, the liquid is discharged from the drain valve (18); when the water volume in the clean water tank (10) is insufficient in step S4, water is inlet from the water replenishing valve (19).

7. The water washing process of the three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion according to claim 5, characterized in that: The washing liquid pump (2) in steps S2 - S4 and the valves in steps S1 - S4 are automatically set for the start-stop sequence of opening and closing by the control system.

8. The water washing process of the three-stage countercurrent water washing device for calcium carbonate based on gypsum conversion according to claim 5, characterized in that: All the valves in steps S1 - S4 adopt pneumatic valves.

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