CN213037610U

CN213037610U - Resourceful treatment system of magnesium sulfate waste water

Info

Publication number: CN213037610U
Application number: CN202021748112.2U
Authority: CN
Inventors: 杨杰; 许亮; 王玉立; 霍健; 张洪彩; 智丹丹; 费娟娟
Original assignee: Jiangsu Maiande Energy Saving Evaporation Equipment Co ltd
Current assignee: Jiangsu Maiande Energy Saving Evaporation Equipment Co ltd
Priority date: 2020-08-20
Filing date: 2020-08-20
Publication date: 2021-04-23
Anticipated expiration: 2030-08-20

Abstract

The utility model relates to a resourceful processing system of magnesium sulfate waste water, including the charge pump, the export of charge pump links to each other with the feed inlet of two effect evaporation plant, two effect evaporation plant's discharge gate links to each other with the feed inlet of one effect evaporation plant through two effect rotary feed pump, one effect evaporation plant's discharge gate links to each other through the entry of one effect discharge pump with the crystallizer, the discharge gate of crystallizer passes through the crystallizer discharge pump and links to each other with the feed inlet of rotary crystal cooling crystallizer, the discharge gate of rotary crystal cooling crystallizer passes through the rotary crystal discharge pump and links to each other with the feed inlet of centrifuge, the liquid phase export of centrifuge links to each other with the entry of centrifuge mother liquor jar one, the bottom export of centrifuge mother liquor jar one passes through the feed inlet of plate frame charge pump with the plate frame filter press and links to each other, the liquid. The system can respectively extract magnesium sulfate, calcium sulfate and magnesium chloride from waste water containing mixed salt, and reaches the zero emission standard of pollutants.

Description

Resourceful treatment system of magnesium sulfate waste water

Technical Field

The utility model relates to a magnesium sulfate waste water's processing system especially relates to a magnesium sulfate waste water's resourceful treatment system, belongs to industrial waste liquid utilization technical field.

Background

Magnesium sulfate has various crystal salts in the production process, and magnesium sulfate monohydrate, magnesium sulfate dihydrate, magnesium sulfate trihydrate, magnesium sulfate pentahydrate, magnesium sulfate hexahydrate and magnesium sulfate heptahydrate can be generated, wherein the magnesium sulfate monohydrate and the magnesium sulfate heptahydrate are usually sold as industrial products.

At present, the treatment process of rare earth smelting magnesium sulfate wastewater at home and abroad is summarized mainly by an evaporation concentration method, an alkaline method, a lime method and the like. The evaporation concentration method has high steam consumption and highest treatment cost. The alkaline method can prepare magnesium hydroxide, but the formation of sodium sulfate mother liquor requires further treatment, the process is complex, and the mother liquor treatment cost is higher. The lime method is to add calcium oxide to react with the magnesium sulfate wastewater to generate magnesium hydroxide and calcium sulfate precipitates, the reaction yield is unstable, the granularity of the calcium sulfate is small, the calcium sulfate is too ideal, and the success in industrial application is difficult to achieve. The methods play a certain role in processing rare earth smelting, but have the defects of high energy consumption, high operating cost, unstable product, difficult maintenance and operation, large investment, large occupied area and poor sewage purification effect to different degrees, and only when the method is processed to reach the standard and discharged, secondary mother liquor can be formed, resources such as water and the like can not be recovered, and the final treatment can not be realized.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome the problem that exists among the prior art, provide a resourceful treatment system of magnesium sulfate waste water, can draw magnesium sulfate, calcium sulfate and magnesium chloride in the waste water solution that contains the mixed salt, changing waste into valuables, and realize the zero release.

In order to solve the technical problem, the utility model discloses a resourceful treatment system of magnesium sulfate waste water, including charge pump 2, the export of charge pump 2 links to each other with the feed inlet of two effect evaporation plant, two effect evaporation plant's discharge gate links to each other with one effect evaporation plant's feed inlet through two effect commentaries on classics material pump 9, one effect evaporation plant's discharge gate links to each other with the entry of crystallizer 19 through one effect discharge pump 14, the discharge gate of crystallizer 19 links to each other with the feed inlet of commentaries on classics brilliant cooling crystallizer 21 through crystallizer discharge pump 20, the discharge gate of commentaries on classics brilliant cooling crystallizer 21 links to each other with the feed inlet of centrifuge 25 through commentaries on classics brilliant discharge pump 24, centrifuge 25's solid phase outlet links to each other with; the liquid phase outlet of the centrifuge 25 is connected with the inlet of the first centrifuge mother liquor tank 26, the bottom outlet of the first centrifuge mother liquor tank 26 is connected with the feed inlet of the plate-and-frame filter press 30 through the plate-and-frame feed pump 29, and the liquid phase outlet of the plate-and-frame filter press 30 is connected with the inlet of the second centrifuge mother liquor tank 27.

Compared with the prior art, the utility model discloses following beneficial effect has been obtained: the magnesium sulfate production wastewater contains impurities such as magnesium chloride, calcium sulfate and the like, and is subjected to double-effect evaporation concentration, calcium sulfate saturated crystallization, magnesium chloride and magnesium sulfate concentration, and then is sent to a single-effect evaporation device through a double-effect transfer pump 9 to be subjected to single-effect evaporation, so that magnesium sulfate is saturated to generate crystallization, the magnesium chloride is further concentrated, a solution containing magnesium sulfate crystal slurry enters a crystallization tank 19 to be subjected to reduced pressure evaporation, the magnesium sulfate is further crystallized and then enters a crystal transfer cooling crystallizer 21 to be further cooled and crystallized, and then is sent to a centrifuge 25 through a crystal transfer discharge pump 24 to be subjected to centrifugal filtration to obtain magnesium sulfate heptahydrate with crystal water, and then is sent to a fluidized bed 53 to be dried to obtain magnesium sulfate monohydrate with the purity of more than 99%; and the liquid phase separated by the centrifuge 25 enters a centrifuge mother liquor tank I26 for sedimentation, calcium sulfate is precipitated to the bottom of the centrifuge mother liquor tank I26, is pumped out by a plate-and-frame feeding pump 29 and is sent to a plate-and-frame filter press 30 for filter pressing, and calcium sulfate solid is obtained. The utility model extracts magnesium sulfate heptahydrate from non-pure magnesium sulfate, removes and recovers other miscellaneous salts, and realizes zero discharge. The recovery rate of the magnesium sulfate heptahydrate can reach 94 percent, and other miscellaneous salts can be removed to realize zero emission.

As the improvement of the utility model, the overflow mouth of the centrifuge mother liquor tank II 27 is connected with the feed inlet of the single-effect evaporation device through the mother liquor pump 28, the discharge port of the single-effect evaporation device is connected with the feed inlet of the reaction kettle through the single-effect discharge pump 31, and the discharge port of the reaction kettle is connected with the inlet of the scraper 36 through the reaction kettle discharge pump. Pumping the mother liquor with most of the recovered magnesium sulfate out by a mother liquor pump 28, sending the mother liquor into a single-effect evaporation device for continuous evaporation, and then feeding the solution subjected to single-effect evaporation into a reaction kettle for heating evaporation to increase the concentration of magnesium chloride to 47% wt; because the boiling point of magnesium chloride is very high, pure evaporation can't obtain fashioned magnesium chloride hexahydrate, the utility model discloses send into high concentration magnesium chloride and cool off in the scraping machine 36, make magnesium chloride and sodium sulfate glue the wall, obtain the magnesium chloride bittern piece that contains the magnesium sulfate through the scraper scraping material, do not contain the mother liquor almost, can sell as the snow melt agent.

As the further improvement of the utility model, one imitate, two effect, single effect evaporation plant is respectively including the separator that connects gradually, the heating evaporimeter, circulating pump and reheat evaporimeter, two effect separator 10, the steam outlet of single effect separator 15 all links to each other with centrifugal compressor 52's inlet pipeline, one imitates heating evaporimeter 6, the heat medium entry of single effect heating evaporimeter 16 and single effect reheat evaporimeter 17 all links to each other with centrifugal compressor 52's outlet pipe, the steam outlet of one effect separator 5 links to each other with two effect heating evaporimeter 11 and the heat medium entry of two effect reheat evaporimeter 12. The MVR mixed evaporation process is adopted, secondary steam of the two-effect and the single-effect enters a centrifugal compressor, the first effect and the single-effect are heated after the centrifugal compressor works, the secondary steam generated by the first effect is used as a heat source of the two-effect evaporation device, the characteristic that the boiling point of material liquid changes along with the concentration is utilized, the multi-stage evaporation and the centrifugal compressor 52 compression mode is adopted, and the material liquid is sequentially evaporated and crystallized on evaporators of different stages. Compared with single-stage evaporation or two-stage evaporation, the method greatly saves energy consumption, reduces operation cost, ensures continuous operation of the system and improves production efficiency. Need a large amount of moisture of evaporation in the evaporation technology, need consume a large amount of energy and add hot water and produce steam, secondary steam's output is great, and contains a large amount of latent heats of vaporization, the utility model discloses retrieve it and utilize, two effect bodies and vapor compressor establish ties and form closed circuit and make steam cyclic utilization.

As a further improvement of the utility model, the export of charge pump 2 links to each other through one-level heat exchanger 3 and two effect evaporation plant's feed inlet, one imitates heating evaporator 6, two effect heating evaporator 11, the comdenstion water export of single effect heating evaporator 16 and single effect reheat evaporator 17 links to each other through the entry of comdenstion water delivery pipe with condensation water pitcher 39 respectively, the delivery port of condensation water pitcher 39 passes through a condensation water pump 38 and links to each other with one-level heat exchanger 3's heat medium entry, one-level heat exchanger 3's heat medium export links to each other with the comdenstion water recovery pipe. A large amount of condensed water is generated after the first-effect steam, the second-effect steam and the single-effect steam are subjected to heat exchange, and high-temperature condensed water has a high enthalpy value and is completely recycled in a first condensed water tank 39 to serve as a heat source for preheating feed liquid; magnesium sulfate waste water enters a primary heat exchanger 3 through a feeding pump 2, the temperature of the magnesium sulfate waste water is increased through heat exchange with condensed water, the heat inside the system is fully utilized, and the lower the temperature of the finally discharged condensed water is, the lower the energy unit consumption of the whole system is.

As a further improvement of the utility model, the outlet of the single-effect discharge pump 31 is connected with the feed inlet of the first reaction kettle 32, the discharge outlet of the first reaction kettle 32 is connected with the feed inlet of the second reaction kettle 34 through the first reaction kettle discharge pump, and the discharge outlet of the second reaction kettle 34 is connected with the inlet of the second reaction kettle discharge pump 35; the heating medium inlets of the first reaction kettle 32 and the second reaction kettle 34 are connected with a steam generation pipe. The main component of the solution from which the calcium sulfate and most of the magnesium sulfate are separated is magnesium chloride, the magnesium chloride is evaporated and concentrated by a single-effect evaporation device, and then the magnesium chloride enters the first reaction kettle 32 to be continuously evaporated by steam heating, the evaporation intensity of the first reaction kettle 32 and the second reaction kettle 34 is higher, and the temperature of the feed liquid is higher, so that the raw steam with the temperature of 135 ℃ is used as a heat source for heating the jacket. After the concentration of the magnesium chloride is increased to 38% by weight by the first reaction kettle 32, the feed liquid is reacted into the second reaction kettle 34 and is continuously evaporated by steam heating, and the concentration of the magnesium chloride is increased to 47% by weight by the second reaction kettle 34 so as to enter a scraper 36 for scraping.

As the utility model discloses a further improvement, the circulation outlet of changeing brilliant cooling crystallizer 21 links to each other with the feed inlet of changeing brilliant cooling heat exchanger 22 through changeing brilliant circulating pump 23, and the discharge gate of changeing brilliant cooling heat exchanger 22 links to each other with the circulation entry of changeing brilliant cooling crystallizer 21, and the refrigerant export of changeing brilliant cooling crystallizer 21 links to each other with refrigerator 37's entry, and refrigerator 37's export links to each other with the refrigerant entry of changeing brilliant cooling crystallizer 21. The refrigerator 37 cools the refrigerant water with the temperature of 11 ℃ to 6 ℃, sends the refrigerant water to the shell pass of the crystal-transferring cooling heat exchanger 22, indirectly cools the feed liquid, reduces the temperature of the feed liquid to 35 ℃, further reduces the saturation temperature of the magnesium sulfate, and accelerates the crystallization of the magnesium sulfate.

Drawings

The invention will be described in further detail with reference to the drawings and the detailed description, which are provided for reference and illustration purposes only and are not intended to limit the invention.

FIG. 1 is a flow chart of a first embodiment of a recycling treatment system for magnesium sulfate production wastewater.

FIG. 2 is a flow chart of a second embodiment of the recycling treatment system for magnesium sulfate production wastewater of the present invention.

In the figure: 1. a feed buffer tank; 2. a feed pump; 3. a primary heat exchanger; 4. a secondary heat exchanger; 5. a first effect separator; 6. a first effect heating evaporator; 7. a one-effect reheat evaporator; 8. a one-effect circulation pump; 9. a two-effect material transfer pump; 10. a two-effect separator; 11. a dual-effect heating evaporator; 12. a two-effect reheat evaporator; 13. a two-effect circulating pump; 14. a first effect discharge pump; 15. a single effect separator; 16. a single effect heating evaporator; 17. a single effect reheat evaporator; 18. a single-effect circulation pump; 19. a crystallization tank; 20. a crystallizing tank discharge pump; 21. crystal transformation cooling crystallizer; 22. a crystal transformation cooling heat exchanger; 23. a crystal rotating circulating pump; 24. a crystal rotating discharge pump; 25. a centrifuge; 26. a centrifuge mother liquor tank I; 27. a centrifuge mother liquor tank II; 28. a mother liquor pump; 29. a plate frame feed pump; 30. a plate-and-frame filter press; 31. a single-effect discharge pump; 32. a first reaction kettle; 33. a first material transferring pump of the reaction kettle; 34. a second reaction kettle; 35. a second discharging pump of the reaction kettle; 36. a scraping machine; 37. a freezer; 38. a first condensate pump; 39. a first condensate tank; 40. a first surface cooler; 41. a first vacuum pump; 42. a water cooling tower; 43. a vacuum pump II; 44. a second surface cooler; 45. a vacuum pump III; 46. a third surface cooler; 47. a vacuum pump IV; 48. a second condensed water tank; 49. a second condensate pump; 50. a third condensate tank; 51. a third condensate pump; 52. a centrifugal compressor; 53. a fluidized bed; G1. a feed pipe; G2. a raw steam pipe.

Detailed Description

As shown in fig. 1, the utility model discloses a resourceful treatment system of magnesium sulfate waste water, including the feeding buffer tank 1 that links to each other with inlet pipe G1, the export of charge-in pump 2 links to each other with the feed inlet of two effect evaporation plant, two effect evaporation plant's discharge gate links to each other with one effect evaporation plant's feed inlet through two effect material transfer pump 9, one effect evaporation plant's discharge gate links to each other with the entry of crystallizer 19 through one effect discharge pump 14, the discharge gate of crystallizer 19 links to each other with the feed inlet of transcrystalline cooling 21 through crystallizer discharge pump 20, the discharge gate of transcrystalline cooling crystallizer 21 links to each other with the feed inlet of centrifuge 25 through transcrystalline discharge pump 24, the solid phase export of centrifuge 25 links to each other with the entry of fluidized bed 53; the liquid phase outlet of the centrifuge 25 is connected with the inlet of the first centrifuge mother liquor tank 26, the bottom outlet of the first centrifuge mother liquor tank 26 is connected with the feed inlet of the plate-and-frame filter press 30 through the plate-and-frame feed pump 29, and the liquid phase outlet of the plate-and-frame filter press 30 is connected with the inlet of the second centrifuge mother liquor tank 27.

The magnesium sulfate production wastewater contains impurities such as magnesium chloride, calcium sulfate and the like, and is subjected to double-effect evaporation concentration, calcium sulfate saturated crystallization, magnesium chloride and magnesium sulfate concentration, and then is sent to a single-effect evaporation device through a double-effect transfer pump 9 to be subjected to single-effect evaporation, so that magnesium sulfate is saturated to generate crystallization, the magnesium chloride is further concentrated, a solution containing magnesium sulfate crystal slurry enters a crystallization tank 19 to be subjected to reduced pressure evaporation, the magnesium sulfate is further crystallized and then enters a crystal transfer cooling crystallizer 21 to be further cooled and crystallized, and then is sent to a centrifuge 25 through a crystal transfer discharge pump 24 to be subjected to centrifugal filtration to obtain magnesium sulfate heptahydrate with crystal water, and then is sent to a fluidized bed 53 to be dried to obtain magnesium sulfate monohydrate with the purity of more than 99%; and the liquid phase separated by the centrifuge 25 enters a centrifuge mother liquor tank I26 for sedimentation, calcium sulfate is precipitated to the bottom of the centrifuge mother liquor tank I26, is pumped out by a plate-and-frame feeding pump 29 and is sent to a plate-and-frame filter press 30 for filter pressing, and calcium sulfate solid is obtained. The utility model extracts magnesium sulfate heptahydrate from non-pure magnesium sulfate, removes and recovers other miscellaneous salts, and realizes zero discharge. The recovery rate of the magnesium sulfate heptahydrate can reach 94 percent, and other miscellaneous salts can be removed to realize zero emission.

The overflow port of the second centrifuge mother liquor tank 27 is connected with the feed inlet of the single-effect evaporation device through a mother liquor pump 28, the discharge port of the single-effect evaporation device is connected with the feed inlet of the reaction kettle through a single-effect discharge pump 31, and the discharge port of the reaction kettle is connected with the inlet of a scraper 36 through a reaction kettle discharge pump. Pumping the mother liquor with most of the recovered magnesium sulfate out by a mother liquor pump 28, sending the mother liquor into a single-effect evaporation device for continuous evaporation, and then feeding the solution subjected to single-effect evaporation into a reaction kettle for heating evaporation to increase the concentration of magnesium chloride to 47% wt; because the boiling point of magnesium chloride is very high, pure evaporation can't obtain fashioned magnesium chloride hexahydrate, the utility model discloses send into high concentration magnesium chloride and cool off in the scraping machine 36, make magnesium chloride and sodium sulfate glue the wall, obtain the magnesium chloride bittern piece that contains the magnesium sulfate through the scraper scraping material, do not contain the mother liquor almost, can sell as the snow melt agent.

The first-effect, second-effect and single-effect evaporation devices respectively comprise separators, heating evaporators, circulating pumps and reheating evaporators which are sequentially connected, steam outlets of the second-effect separator 10 and the single-effect separator 15 are connected with an inlet pipeline of a centrifugal compressor 52, heat medium inlets of the first-effect heating evaporators 6, the single-effect heating evaporators 16 and the single-effect reheating evaporators 17 are connected with an outlet pipe of the centrifugal compressor 52, and a steam outlet of the first-effect separator 5 is connected with heat medium inlets of the second-effect heating evaporators 11 and the second-effect reheating evaporators 12.

The MVR mixed evaporation process is adopted, the secondary steam temperature of the two-effect evaporator and the single-effect evaporator is 85 ℃, the secondary steam enters a centrifugal compressor, the compressed steam temperature at the outlet of the centrifugal compressor 52 is 105 ℃, the primary steam and the single-effect evaporator are heated, the secondary steam temperature generated by the primary steam is 93 ℃, the secondary steam serves as a heat source of the two-effect evaporation device, the characteristic that the boiling point of the material liquid changes along with the concentration is utilized, the multi-stage evaporation and centrifugal compressor 52 compression mode is adopted, and the material liquid is sequentially subjected to evaporation crystallization on different stages of evaporators. Compared with single-stage evaporation or two-stage evaporation, the method greatly saves energy consumption, reduces operation cost, ensures continuous operation of the system and improves production efficiency. Need a large amount of moisture of evaporation in the evaporation technology, need consume a large amount of energy and add hot water and produce steam, secondary steam's output is great, and contains a large amount of latent heats of vaporization, the utility model discloses retrieve it and utilize, two effect bodies and vapor compressor establish ties and form closed circuit and make steam cyclic utilization.

The outlet of the feed pump 2 is connected with the feed inlet of the double-effect evaporator through the primary heat exchanger 3, the condensed water outlets of the first-effect heating evaporator 6, the double-effect heating evaporator 11, the single-effect heating evaporator 16 and the single-effect reheating evaporator 17 are respectively connected with the inlet of a condensed water tank I39 through condensed water discharge pipes, the water outlet of the condensed water tank I39 is connected with the heat medium inlet of the primary heat exchanger 3 through a condensed water pump I38, and the heat medium outlet of the primary heat exchanger 3 is connected with a condensed water recovery pipe. A large amount of condensed water is generated after the first-effect steam, the second-effect steam and the single-effect steam are subjected to heat exchange, and high-temperature condensed water has a high enthalpy value and is completely recycled in a first condensed water tank 39 to serve as a heat source for preheating feed liquid; magnesium sulfate waste water enters a primary heat exchanger 3 through a feeding pump 2, the temperature of the magnesium sulfate waste water is increased through heat exchange with condensed water, the heat inside the system is fully utilized, and the lower the temperature of the finally discharged condensed water is, the lower the energy unit consumption of the whole system is.

As shown in fig. 2, the exhaust ports of the first-effect heating evaporator 6, the second-effect heating evaporator 11, the single-effect heating evaporator 16 and the single-effect reheating evaporator 17 are connected with the air inlet of a first surface air cooler 40, and the exhaust port of the first surface air cooler 40 is connected with the inlet of a first vacuum pump 41; a discharge port of the primary heat exchanger 3 is connected with a feed port of the surface cooler I40, a discharge port of the surface cooler I40 is connected with a feed port of the secondary heat exchanger 4, and a discharge port of the secondary heat exchanger 4 is connected with a feed port of the secondary evaporation device; a heating medium inlet of the secondary heat exchanger 4 is connected with the raw steam pipe G2, and a condensed water outlet of the secondary heat exchanger 4 is connected with an inlet of the condensed water tank I39. And the magnesium sulfate wastewater after primary temperature rise enters a surface cooler I40 to continue temperature rise, then enters a secondary heat exchanger 4, the temperature of the magnesium sulfate wastewater is heated to 87.4 ℃ through raw steam at 135 ℃, the energy consumption of the system is reduced, condensed water generated by preheating of the secondary heat exchanger 4 is recycled to a condensed water tank I39, and the energy consumption is further reduced.

The top exhaust port of the crystallizing tank 19 is connected with the inlet of a water cooling tower 42, and the outlet of the water cooling tower 42 is connected with the inlet of a second vacuum pump 43. Under the suction action of the second vacuum pump 43, the flash steam of the crystallization tank 19 enters the water cooling tower 42 for condensation, and the water cooling tower 42 utilizes water as a refrigerant, so that not only is the heat of the system absorbed, but also the pressure of the inner cavity of the crystallization tank 19 is reduced, the evaporation temperature of the crystallization tank is greatly reduced, the temperature of the feed liquid is rapidly reduced, and the precipitation of magnesium sulfate is facilitated.

The outlet of the single-effect discharge pump 31 is connected with the feed inlet of the first reaction kettle 32, the discharge outlet of the first reaction kettle 32 is connected with the feed inlet of the second reaction kettle 34 through the first reaction kettle discharge pump, and the discharge outlet of the second reaction kettle 34 is connected with the inlet of the second reaction kettle discharge pump 35; the exhaust port of the first reaction kettle 32 is connected with the air inlet of the second surface cooler 44, and the exhaust port of the second surface cooler 44 is connected with the inlet of the third vacuum pump 45; the exhaust port of the second reaction kettle 34 is connected with the air inlet of the third surface cooler 46, and the exhaust port of the third surface cooler 46 is connected with the inlet of the fourth vacuum pump 47; and the condensed water outlets of the second surface air cooler 44 and the third surface air cooler 46 are respectively connected with the inlet of a second condensed water tank 48, and the water outlet of the second condensed water tank 48 is connected with a condensed water recovery pipe through a second condensed water pump 49.

The main component of the solution from which the calcium sulfate and most of the magnesium sulfate are separated is magnesium chloride, the solution is evaporated and concentrated by a single-effect evaporation device, the solution enters a first reaction kettle 32 to be continuously evaporated through steam heating, non-condensable gas in the first reaction kettle 32 is discharged under the suction action of a third vacuum pump 45, secondary steam generated by evaporation enters a second surface air cooler 44 to exchange heat, and condensed water enters a second condensed water tank 48 to be collected; after the concentration of magnesium chloride is increased to 38% by weight by the first reaction kettle 32, the feed liquid is reversely fed into the second reaction kettle 34 to be continuously evaporated through steam heating, under the suction action of a fourth vacuum pump 47, non-condensable gas in the second reaction kettle 34 is discharged, secondary steam generated by evaporation is fed into a third surface air cooler 46 to exchange heat, condensed water is also fed into a second condensed water tank 48 to be collected, and then is fed into a condensed water recycling pipe through a second condensed water pump 49 to utilize waste heat; the second reaction kettle 34 increases the concentration of the magnesium chloride to 47 wt% so as to enter a scraper 36 for scraping.

Heating medium inlets of the first reaction kettle 32 and the second reaction kettle 34 are connected with a raw steam pipe G2, condensed water outlets of the first reaction kettle 32 and the second reaction kettle 34 are respectively connected with an inlet of a third condensed water tank 50 through a condensed water discharge pipe, and a water outlet of the third condensed water tank 50 is connected with a condensed water recovery pipe through a third condensed water pump 51. The evaporation intensity of the first reaction kettle 32 and the second reaction kettle 34 is relatively high, and the temperature of the material liquid is relatively high, so that raw steam with the temperature of 135 ℃ is used as a heat source for heating the jacket, high-temperature condensed water discharged by the jacket enters the third condensed water tank 50 for collection, and then is sent to a condensed water recycling pipe by the third condensed water pump 51 for recycling waste heat.

The circulating outlet of the crystal transfer cooling crystallizer 21 is connected with the feeding hole of the crystal transfer cooling heat exchanger 22 through a crystal transfer circulating pump 23, the discharging hole of the crystal transfer cooling heat exchanger 22 is connected with the circulating inlet of the crystal transfer cooling crystallizer 21, the refrigerant outlet of the crystal transfer cooling crystallizer 21 is connected with the inlet of a refrigerator 37, and the outlet of the refrigerator 37 is connected with the refrigerant inlet of the crystal transfer cooling crystallizer 21. The refrigerator 37 cools the refrigerant water with the temperature of 11 ℃ to 6 ℃, sends the refrigerant water to the shell pass of the crystal-transferring cooling heat exchanger 22, indirectly cools the feed liquid, reduces the temperature of the feed liquid to 35 ℃, further reduces the saturation temperature of the magnesium sulfate, and accelerates the crystallization of the magnesium sulfate.

The working process of the magnesium sulfate production wastewater zero-discharge recycling treatment system sequentially comprises the following steps of 1: magnesium sulfate production wastewater contains 1.25 wt% of magnesium chloride, 12.5 wt% of magnesium sulfate and 0.2 wt% of calcium sulfate, the magnesium sulfate production wastewater is pumped out from a feeding buffer tank 1 by a feeding pump 2, is sequentially preheated by a first-stage heat exchanger 3 for the first time, is heated by a surface cooler for the first 40 time and is heated by a second-stage heat exchanger for the third 4 times, a raw material solution is heated to 87.4 ℃, the material circulation temperature of a second-effect separator 10 is also 87.4 ℃, and the raw material solution and the discharge material from the second-effect heating evaporator 11 are jointly sent into a second-effect reheating evaporator 12 by a second-effect circulating pump 13 for reheating, then enter the second-effect separator 10 for double-effect evaporation, and a salt-containing solution enters the second-effect reheating evaporator 11 for heating and is maintained to circulate by the second-effect circulating pump 13; after the double-effect evaporation and concentration, the solution contains 2.06 wt% of magnesium chloride and 20.6 wt% of magnesium sulfate, and calcium sulfate is crystallized; the two-effect steam discharged from the top of the two-effect separator 10 is compressed by a centrifugal compressor 52 and then is used as a heat source of a one-effect heating evaporator 6, a one-effect reheating evaporator 7, a single-effect heating evaporator 16 and a single-effect reheating evaporator 17;

step 2: part of discharged materials of the two-effect circulating pump 13 are pumped out by a two-effect material transfer pump 9, the discharged materials and the first-effect materials from the first-effect heating evaporator 6 are sent into the first-effect reheating evaporator 7 by the first-effect circulating pump 8 to be reheated, and then enter the first-effect separator 5 to be subjected to one-effect evaporation, the first-effect solution enters the first-effect heating evaporator 6 to be heated and is maintained to circulate by the first-effect circulating pump 8, the material circulating temperature of the first-effect separator 5 is 101 ℃, after the first-effect evaporation is continued to be concentrated, part of magnesium sulfate is crystallized, and the solution containing magnesium sulfate crystal slurry discharged by the first-effect separator 5 contains 14.4 wt% of magnesium chloride and 14 wt% of magnesium sulfate; the first-effect steam discharged from the top of the first-effect separator 5 is used as a heat source of the second-effect heating evaporator 11 and the second-effect reheating evaporator 12;

and step 3: the discharge of the primary effect separator 5 is sent into a crystallizing tank 19 by a primary effect discharge pump 14 for decompression and evaporation, the discharge temperature of the crystallizing tank 19 is 55 ℃, and after the magnesium sulfate is further crystallized, the solution contains 16 wt% of magnesium chloride and 11 wt% of magnesium sulfate; under the suction action of a second vacuum pump 43, the exhaust gas at the top of the crystallization tank 19 is condensed by a water cooling tower 42 and then discharged; the discharge of the crystallizing tank 19 is pumped out by a crystallizing tank discharge pump 20, and is sent into a crystal transfer cooling heat exchanger 22 by a crystal transfer circulating pump 23 together with overflow materials from the crystal transfer cooling crystallizer 21 to be cooled to 35 ℃, and then is returned to the crystal transfer cooling crystallizer 21 for circulation, after the magnesium sulfate is further crystallized, the solution contains 19 wt% of magnesium chloride and 5 wt% of magnesium sulfate;

and 4, step 4: the bottom discharge of the crystal transfer cooling crystallizer 21 is sent into a centrifuge 25 by a crystal transfer discharge pump 24 for centrifugal filtration to obtain magnesium sulfate heptahydrate with crystal water, and then sent into a fluidized bed 53 for drying to obtain magnesium sulfate monohydrate with the purity of more than 99 percent; the liquid phase separated by the centrifuge 25 enters a centrifuge mother liquor tank I26 for sedimentation, calcium sulfate is precipitated to the bottom of the centrifuge mother liquor tank I26, is pumped out by a plate-and-frame feeding pump 29 and is sent to a plate-and-frame filter press 30 for filter pressing to obtain calcium sulfate solid, and filter pressing clear liquid enters a centrifuge mother liquor tank II 27;

and 5: the overflow mother liquor of the centrifuge mother liquor tank II 27 is pumped out by a mother liquor pump 28, and is sent into a single-effect reheating evaporator 17 by a single-effect circulating pump 18 together with the discharge from the single-effect heating evaporator 16 for reheating, then the overflow mother liquor enters a single-effect separator 15 for single-effect evaporation, the single-effect solution enters the single-effect heating evaporator 16 for heating and is maintained to circulate by the single-effect circulating pump 18, the material circulation and discharge temperature of the single-effect separator 15 is 98 ℃, and the single-effect discharged solution contains 25 wt% of magnesium chloride and 6.58 wt% of magnesium sulfate; the single-effect steam discharged from the top of the single-effect separator 15 is also compressed in the centrifugal compressor 52;

step 6: the discharging material of the single-effect separator 15 is sent into a first reaction kettle 32 by a single-effect discharging pump 31 to be heated to 100 ℃, and is stirred and evaporated, the discharging material of the first reaction kettle 32 enables the concentration of magnesium chloride to be increased to 38% wt, and the concentration of magnesium sulfate to be increased to 10% wt; and (3) feeding the mixture into a second reaction kettle 34 through a first reaction kettle material transferring pump 33, continuously heating the mixture to 110 ℃, stirring and evaporating the mixture, discharging the mixture from the second reaction kettle 34 to improve the concentration of magnesium chloride to 47 wt% and the concentration of magnesium sulfate to 12.4 wt%, feeding the mixture into a second reaction kettle material discharging pump 35 to a scraper 36 to cool the sticky wall, and scraping the mixture through a scraper to obtain the magnesium chloride halogen slice containing the magnesium sulfate.

The hot side of the secondary heat exchanger 4 adopts raw steam as a heat source, condensed water at the hot sides of the secondary heat exchanger 4, the first-effect heating evaporator 6, the first-effect reheating evaporator 7, the second-effect heating evaporator 11, the second-effect reheating evaporator 12, the single-effect heating evaporator 16 and the single-effect reheating evaporator 17 is respectively discharged into a first condensed water tank 39, a first condensed water pump 38 sends high-temperature condensed water in the first condensed water tank 39 into the hot side of the primary heat exchanger 3 as the heat source, and the condensed water discharged at the hot side of the primary heat exchanger 3 enters a condensed water recovery pipe for recovery; under the suction action of the first vacuum pump 41, the flash steam of the first condensate water tank 39 enters the first surface cooler 40 for heat exchange, and the condensate water also enters the first condensate water tank 39.

The hot sides of the first reaction kettle 32 and the second reaction kettle 34 adopt raw steam as a heat source for heating the jackets, condensed water discharged from the jackets of the first reaction kettle 32 and the second reaction kettle 34 enters a third condensed water tank 50 for temporary storage, and then is pumped out by a third condensed water pump 51 and sent into a condensed water recovery pipe for recovery; under the suction of a third vacuum pump 45, the flash steam discharged from the top of the first reaction kettle 32 enters a second surface air cooler 44 for condensation, and the condensed water enters a second condensed water tank 48 for temporary storage; under the suction of a vacuum pump IV 47, flash steam discharged from the top of the second reaction kettle 34 enters a surface air cooler III 46 for condensation, condensed water also enters a condensed water tank II 48 for temporary storage, and then is pumped out by a condensed water pump II 49 and sent into a condensed water recovery pipe for recovery.

Magnesium sulfate waste water is earlier through two-effect evaporative concentration, and the magnesium chloride concentration in two-effect is only 2.06% wt, and 20.6% wt's magnesium sulfate does not reach its saturated concentration 30% wt, consequently only calcium sulfate at first reaches the saturated crystallization, because the granule of calcium sulfate is little, can't separate through centrifuge, the utility model discloses take to stay the calcium sulfate in two-effect solution earlier, get into one and imitate continuous evaporative concentration.

Through one-effect evaporation, the concentration of magnesium chloride reaches 14.4 percent by weight, the saturated concentration of magnesium sulfate is reduced to 14 percent by weight, a large amount of magnesium sulfate is crystallized, the solution containing magnesium sulfate crystal slurry enters a crystallizing tank 19 for decompression and evaporation, then enters a crystal rotating cooling crystallizer 21 for further cooling and crystallization, then 93.5 percent of magnesium sulfate heptahydrate is separated out through a centrifuge 25, and after drying through a fluidized bed 53, high-purity magnesium sulfate monohydrate with the purity of more than 99 percent is obtained and can be directly sold as an industrial finished product.

Because the calcium sulfate particles are small, the calcium sulfate particles enter a centrifuge mother liquor tank I26 to be precipitated and are filtered out through a plate-and-frame filter press 30. At this time, the amount of the solution is greatly reduced and the content of calcium sulfate is small, so that the plate-and-frame filter press 30 is lightly loaded.

The main components of the separated residual solution of magnesium sulfate and calcium sulfate are magnesium chloride and a small amount of residual magnesium sulfate, the solution amount is further reduced, the magnesium chloride and the small amount of residual magnesium sulfate are sent to a single-effect evaporation device for further concentration, then the evaporation concentration is continued through a first reaction kettle 32 and a second reaction kettle 34, aiming at the characteristic that the boiling point of magnesium chloride is very high, high-concentration magnesium chloride is sent to a scraping machine 36 for cooling, the magnesium chloride and sodium sulfate are adhered to the wall, a magnesium chloride halogen sheet containing magnesium sulfate is obtained by scraping materials through a scraper, and the magnesium chloride halogen sheet almost does not contain mother liquor and can be sold as a snow melting agent.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention. In addition to the above embodiments, the present invention can also have other embodiments, and all technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope of the present invention. The undescribed technical features of the present invention can be realized by or using the prior art, and are not described herein again.

Claims

1. The utility model provides a resourceful treatment system of magnesium sulfate waste water, includes charge pump (2), its characterized in that: the outlet of the feed pump (2) is connected with the feed inlet of the double-effect evaporation device, the discharge outlet of the double-effect evaporation device is connected with the feed inlet of the first-effect evaporation device through a double-effect material transferring pump (9), the discharge outlet of the first-effect evaporation device is connected with the inlet of a crystallizing tank (19) through a first-effect discharge pump (14), the discharge outlet of the crystallizing tank (19) is connected with the feed inlet of a crystal transferring cooling crystallizer (21) through a crystallizing tank discharge pump (20), the discharge outlet of the crystal transferring cooling crystallizer (21) is connected with the feed inlet of a centrifugal machine (25) through a crystal transferring discharge pump (24), and the solid phase outlet of the centrifugal machine (25) is connected with the inlet of a fluidized bed (53); the liquid phase outlet of the centrifuge (25) is connected with the inlet of a first centrifuge mother liquor tank (26), the bottom outlet of the first centrifuge mother liquor tank (26) is connected with the feed inlet of a plate-and-frame filter press (30) through a plate-and-frame feed pump (29), and the liquid phase outlet of the plate-and-frame filter press (30) is connected with the inlet of a second centrifuge mother liquor tank (27).

2. The magnesium sulfate production wastewater recycling treatment system according to claim 1, characterized in that: the overflow port of the centrifuge mother liquor tank II (27) is connected with the feed inlet of the single-effect evaporation device through a mother liquor pump (28), the discharge port of the single-effect evaporation device is connected with the feed inlet of the reaction kettle through a single-effect discharge pump (31), and the discharge port of the reaction kettle is connected with the inlet of a scraping machine (36) through the reaction kettle discharge pump.

3. The magnesium sulfate production wastewater recycling treatment system according to claim 2, characterized in that: the single-effect evaporator comprises a separator, a heating evaporator, a circulating pump and a reheating evaporator which are sequentially connected, steam outlets of the two-effect separator (10) and the single-effect separator (15) are connected with an inlet pipeline of a centrifugal compressor (52), heat medium inlets of the single-effect heating evaporator (6), the single-effect heating evaporator (16) and the single-effect reheating evaporator (17) are connected with an outlet pipe of the centrifugal compressor (52), and a steam outlet of the single-effect separator (5) is connected with heat medium inlets of the two-effect heating evaporator (11) and the two-effect reheating evaporator (12).

4. The magnesium sulfate production wastewater recycling treatment system according to claim 3, characterized in that: the outlet of the feed pump (2) is connected with the feed inlet of the double-effect evaporator through the first-stage heat exchanger (3), the condensed water outlets of the first-effect heating evaporator (6), the double-effect heating evaporator (11), the single-effect heating evaporator (16) and the single-effect reheating evaporator (17) are respectively connected with the inlet of a condensed water tank I (39) through a condensed water discharge pipe, the water outlet of the condensed water tank I (39) is connected with the heat medium inlet of the first-stage heat exchanger (3) through a condensed water pump I (38), and the heat medium outlet of the first-stage heat exchanger (3) is connected with a condensed water recovery pipe.

5. The magnesium sulfate production wastewater recycling treatment system according to claim 2, characterized in that: the outlet of the single-effect discharge pump (31) is connected with the feed inlet of the first reaction kettle (32), the discharge outlet of the first reaction kettle (32) is connected with the feed inlet of the second reaction kettle (34) through the first reaction kettle discharge pump, the discharge outlet of the second reaction kettle (34) is connected with the inlet of the second reaction kettle discharge pump (35), and the heat medium inlets of the first reaction kettle (32) and the second reaction kettle (34) are connected with the steam generation pipe.

6. The magnesium sulfate production wastewater recycling treatment system according to claim 1, characterized in that: the circulating outlet of the crystal transformation cooling crystallizer (21) is connected with the feeding hole of the crystal transformation cooling heat exchanger (22) through a crystal transformation circulating pump (23), the discharging hole of the crystal transformation cooling heat exchanger (22) is connected with the circulating inlet of the crystal transformation cooling crystallizer (21), the refrigerant outlet of the crystal transformation cooling crystallizer (21) is connected with the inlet of a refrigerator (37), and the outlet of the refrigerator (37) is connected with the refrigerant inlet of the crystal transformation cooling crystallizer (21).