阅读说明：本技术 高碱度浓盐水零排放处理方法及系统 (High-alkalinity strong brine zero-discharge treatment method and system ) 是由 苏志峰 徐文军 杨权 周扬 林金平 刘圣平 于 2021-01-06 设计创作，主要内容包括：本发明公开了一种高碱度浓盐水零排放处理方法及系统,高碱度浓盐水零排放处理方法包括：S1、对浓盐水进行预热处理和蒸发浓缩处理,获得浓缩液；S2、对浓缩液进行一水碳酸钠蒸发结晶处理,得到一水碳酸钠母液和一水碳酸钠产品盐；S3、对一水碳酸钠母液进行冷冻结晶处理和热熔处理,得到冷冻母液和一水碳酸钠浆液；S4、对冷冻母液进行氯化钠蒸发结晶处理,获得氯化钠母液和氯化钠产品盐。本发明实现对高碱度浓盐水依次进行蒸发浓缩、一水碳酸钠蒸发结晶、十水碳酸钠冷冻结晶、氯化钠蒸发结晶处理,进而实现浓盐水的回收利用,并得到符合国家标准的一水碳酸钠和氯化钠,提高废水的水回收率,保护环境,结晶盐得到资源化利用,实现浓盐水零排放目标。(The invention discloses a high-alkalinity strong brine zero-discharge treatment method and a system, wherein the high-alkalinity strong brine zero-discharge treatment method comprises the following steps: s1, carrying out preheating treatment and evaporation concentration treatment on the strong brine to obtain a concentrated solution; s2, carrying out sodium carbonate monohydrate evaporative crystallization treatment on the concentrated solution to obtain sodium carbonate monohydrate mother liquor and sodium carbonate monohydrate product salt; s3, carrying out freezing crystallization treatment and hot melting treatment on the sodium carbonate monohydrate mother liquor to obtain a frozen mother liquor and sodium carbonate monohydrate slurry; s4, carrying out sodium chloride evaporation crystallization treatment on the frozen mother liquor to obtain sodium chloride mother liquor and sodium chloride product salt. The invention realizes the evaporation concentration, sodium carbonate monohydrate evaporation crystallization, sodium carbonate decahydrate freezing crystallization and sodium chloride evaporation crystallization treatment of the high alkalinity strong brine in sequence, thereby realizing the recycling of the strong brine, obtaining sodium carbonate monohydrate and sodium chloride which meet the national standard, improving the water recovery rate of wastewater, protecting the environment, recycling the crystallized salt and realizing the zero discharge target of the strong brine.)

1. The zero-emission treatment method of the high-alkalinity strong brine is used for zero-emission treatment of sodium carbonate and sodium chloride type strong brine, and is characterized by comprising the following steps of:

s1, sequentially carrying out preheating treatment and evaporation concentration treatment on the strong brine to obtain a concentrated solution;

s2, carrying out sodium carbonate monohydrate evaporative crystallization treatment on the concentrated solution to obtain sodium carbonate monohydrate mother liquor and sodium carbonate monohydrate product salt;

s3, carrying out freezing crystallization treatment and hot melting treatment on the sodium carbonate monohydrate mother liquor to obtain frozen mother liquor and hot-melted sodium carbonate monohydrate slurry;

s4, carrying out sodium chloride evaporation crystallization treatment on the frozen mother liquor to obtain sodium chloride mother liquor and sodium chloride product salt.

2. The high-alkalinity concentrated brine zero-emission treatment method according to claim 1, wherein the step S2 comprises: and (3) carrying out evaporative crystallization treatment on the concentrated solution to obtain sodium carbonate monohydrate slurry, and then sequentially carrying out thickening, centrifuging and drying treatment on the sodium carbonate monohydrate slurry to obtain sodium carbonate monohydrate product salt.

3. The high-alkalinity concentrated brine zero-emission treatment method according to claim 1, wherein the step S3 comprises: and (2) carrying out freezing crystallization treatment on the sodium carbonate monohydrate mother liquor to obtain sodium carbonate decahydrate slurry and freezing mother liquor, and sequentially carrying out thickening, centrifuging and hot melting treatment on the sodium carbonate decahydrate slurry to obtain the sodium carbonate monohydrate slurry.

4. The high-alkalinity concentrated brine zero-emission treatment method according to claim 3, wherein the step S3 further comprises: and sequentially thickening, centrifuging and drying the hot-melted sodium carbonate monohydrate slurry to obtain the sodium carbonate monohydrate product salt.

5. The high-alkalinity concentrated brine zero-emission treatment method according to claim 1, wherein the step S4 comprises: preheating the frozen mother liquor, evaporating and crystallizing to obtain sodium chloride mother liquor and sodium chloride slurry, and then sequentially thickening, centrifuging and drying the sodium chloride slurry to obtain sodium chloride product salt.

6. The high alkalinity concentrated brine zero emission treatment method according to any one of claims 1 to 5, further comprising the steps of:

s5, drying part or all of the sodium chloride mother liquor obtained in the step S4 to obtain mixed salt.

7. A high alkalinity strong brine zero discharge processing system is used for zero discharge processing of sodium carbonate and sodium chloride type strong brine, and is characterized in that the high alkalinity strong brine zero discharge processing system comprises an evaporation concentration device for preheating and concentrating strong brine, a sodium carbonate monohydrate evaporation crystallization device for extracting sodium carbonate monohydrate from a concentrated solution, a sodium carbonate decahydrate freezing crystallization device for freezing, crystallizing and hot-melting mother liquor produced by the sodium carbonate monohydrate evaporation crystallization device, and a sodium chloride evaporation crystallization device for extracting sodium chloride from the frozen mother liquor produced by the sodium carbonate decahydrate freezing crystallization device;

the evaporation concentration device, the sodium carbonate monohydrate evaporation crystallization device, the sodium carbonate decahydrate freezing crystallization device and the sodium chloride evaporation crystallization device are sequentially connected.

8. The high-alkalinity concentrated brine zero-emission treatment system according to claim 7, wherein the evaporation concentration device comprises an evaporation raw water pool, a first preheater and an evaporation concentration unit which are connected in sequence; the evaporation concentration unit is connected with the sodium carbonate monohydrate evaporation crystallization device;

the sodium carbonate monohydrate evaporative crystallization device comprises a sodium carbonate monohydrate evaporative crystallization tank, a first thickener, a first centrifuge and a first dryer which are sequentially connected; the sodium carbonate monohydrate evaporative crystallization tank is connected with the evaporative concentration device and receives concentrated solution from the evaporative concentration device.

9. The high-alkalinity concentrated brine zero-emission treatment system according to claim 8, wherein the sodium carbonate decahydrate freezing and crystallizing device comprises a freezing and crystallizing tank, a second thickener, a second centrifuge and a hot melting tank which are connected in sequence; the freezing crystallization tank is connected with the sodium carbonate monohydrate evaporation crystallization tank and receives mother liquor from the sodium carbonate monohydrate evaporation crystallization tank;

the sodium chloride evaporative crystallization device comprises a sodium chloride evaporative crystallization tank, a third thickener, a third centrifuge and a third dryer which are connected in sequence; the sodium chloride evaporation crystallizing tank is connected with the freezing crystallizing tank and receives the freezing mother liquor from the freezing crystallizing tank.

10. The high-alkalinity concentrated brine zero-emission treatment system according to any one of claims 7 to 9, further comprising a miscellaneous salt drying device for drying the mother liquor produced by the sodium chloride evaporation and crystallization device; the miscellaneous salt drying device is connected with the sodium chloride evaporation crystallization device.

Technical Field

The invention relates to the technical field of wastewater treatment, in particular to a high-alkalinity strong brine zero-discharge treatment method and system.

Background

In the production process of industries such as coal chemical industry, petrifaction, papermaking, metallurgy, mining and the like, a large amount of wastewater such as process system drainage, circulating water sewage, underground water burst in the mining process and the like is generated, the conventional process treatment technologies such as biochemical treatment, chemical dosing treatment, membrane treatment and the like are carried out on the wastewater, only 75% -85% of product water can be recovered from the wastewater, and the rest wastewater is discharged with high-salt-content strong brine to pollute peripheral water sources and ecological environment.

The zero-emission treatment process adopted at home and abroad at present mainly comprises the steps of removing scaling factors in water through a pretreatment unit, realizing concentration and reduction of the strong brine through a membrane concentration unit, and finally realizing separation and extraction of crystal salt in the wastewater through an evaporation crystallization unit to finally realize the aim of zero emission of the wastewater. However, in the production process of some industries, the produced strong brine is mainly sodium carbonate and sodium chloride, the existing zero-emission process can only remove scaling factors through pretreatment and realize concentration and decrement through membrane concentration, but evaporation and crystallization are difficult to realize the recycling of crystallized salt, so that the aim of recycling all wastewater cannot be achieved.

In order to solve the technical problems that the zero-discharge treatment of the strong brine, the zero-discharge treatment process and system adopted at home and abroad at present cannot treat or comprehensively consider the wastewater characteristics of various industries, and cannot realize the recycling treatment of sodium carbonate and sodium chloride type strong brine, a treatment process and system for separating and extracting sodium carbonate and sodium chloride from the strong brine are urgently needed to be found so as to realize the aim of zero discharge of wastewater.

Disclosure of Invention

The invention aims to solve the technical problem of providing a high-alkalinity strong brine zero-emission treatment method and a high-alkalinity strong brine zero-emission treatment system for separating and extracting sodium carbonate and sodium chloride from strong brine.

The technical scheme adopted by the invention for solving the technical problems is as follows: the high-alkalinity strong brine zero-discharge treatment method is used for zero-discharge treatment of sodium carbonate and sodium chloride type strong brine, and comprises the following steps:

s1, sequentially carrying out preheating treatment and evaporation concentration treatment on the strong brine to obtain a concentrated solution;

s2, carrying out sodium carbonate monohydrate evaporative crystallization treatment on the concentrated solution to obtain sodium carbonate monohydrate mother liquor and sodium carbonate monohydrate product salt;

s3, carrying out freezing crystallization treatment and hot melting treatment on the sodium carbonate monohydrate mother liquor to obtain frozen mother liquor and hot-melted sodium carbonate monohydrate slurry;

s4, carrying out sodium chloride evaporation crystallization treatment on the frozen mother liquor to obtain sodium chloride mother liquor and sodium chloride product salt.

Preferably, step S2 includes: and (3) carrying out evaporative crystallization treatment on the concentrated solution to obtain sodium carbonate monohydrate slurry, and then sequentially carrying out thickening, centrifuging and drying treatment on the sodium carbonate monohydrate slurry to obtain sodium carbonate monohydrate product salt.

Preferably, step S3 includes: and (2) carrying out freezing crystallization treatment on the sodium carbonate monohydrate mother liquor to obtain sodium carbonate decahydrate slurry and freezing mother liquor, and sequentially carrying out thickening, centrifuging and hot melting treatment on the sodium carbonate decahydrate slurry to obtain the sodium carbonate monohydrate slurry.

Preferably, step S3 further includes: and sequentially thickening, centrifuging and drying the hot-melted sodium carbonate monohydrate slurry to obtain the sodium carbonate monohydrate product salt.

Preferably, step S4 includes: preheating the frozen mother liquor, evaporating and crystallizing to obtain sodium chloride mother liquor and sodium chloride slurry, and then sequentially thickening, centrifuging and drying the sodium chloride slurry to obtain sodium chloride product salt.

Preferably, the high-alkalinity concentrated brine zero-emission treatment method further comprises the following steps of:

s5, drying part or all of the sodium chloride mother liquor obtained in the step S4 to obtain mixed salt.

The invention also provides a high-alkalinity strong brine zero-discharge treatment system which is used for zero-discharge treatment of sodium carbonate and sodium chloride type strong brine, and comprises an evaporation concentration device for preheating and concentrating the strong brine, a sodium carbonate monohydrate evaporation crystallization device for extracting sodium carbonate monohydrate from the concentrated solution, a sodium carbonate decahydrate freezing crystallization device for freezing, crystallizing and hot-melting the mother solution produced by the sodium carbonate monohydrate evaporation crystallization device, and a sodium chloride evaporation crystallization device for extracting sodium chloride from the frozen mother solution produced by the sodium carbonate decahydrate freezing crystallization device;

the evaporation concentration device, the sodium carbonate monohydrate evaporation crystallization device, the sodium carbonate decahydrate freezing crystallization device and the sodium chloride evaporation crystallization device are sequentially connected.

Preferably, the evaporation concentration device comprises an evaporation raw water pool, a first preheater and an evaporation concentration unit which are connected in sequence; the evaporation concentration unit is connected with the sodium carbonate monohydrate evaporation crystallization device;

the sodium carbonate monohydrate evaporative crystallization device comprises a sodium carbonate monohydrate evaporative crystallization tank, a first thickener, a first centrifuge and a first dryer which are sequentially connected; the sodium carbonate monohydrate evaporative crystallization tank is connected with the evaporative concentration device and receives concentrated solution from the evaporative concentration device.

Preferably, the sodium carbonate decahydrate freezing and crystallizing device comprises a freezing and crystallizing tank, a second thickener, a second centrifuge and a hot melting tank which are connected in sequence; the freezing crystallization tank is connected with the sodium carbonate monohydrate evaporation crystallization tank and receives mother liquor from the sodium carbonate monohydrate evaporation crystallization tank;

the sodium chloride evaporative crystallization device comprises a sodium chloride evaporative crystallization tank, a third thickener, a third centrifuge and a third dryer which are connected in sequence; the sodium chloride evaporation crystallizing tank is connected with the freezing crystallizing tank and receives the freezing mother liquor from the freezing crystallizing tank.

Preferably, the high-alkalinity strong brine zero-emission treatment system further comprises a miscellaneous salt drying device for drying the mother liquor produced by the sodium chloride evaporation and crystallization device; the miscellaneous salt drying device is connected with the sodium chloride evaporation crystallization device.

The invention has the beneficial effects that: the method realizes the evaporation concentration, sodium carbonate monohydrate evaporation crystallization, sodium carbonate decahydrate freezing crystallization and sodium chloride evaporation crystallization treatment of sodium carbonate and sodium chloride type strong brine in sequence, further realizes the recycling of the strong brine, and obtains sodium carbonate monohydrate and sodium chloride which accord with the national standard, thereby not only greatly improving the water recovery rate of wastewater, protecting the environment, but also realizing the resource utilization of the crystallized salt, and really realizing the zero discharge target of the strong brine.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a connection block diagram of a high alkalinity concentrated brine zero emission treatment system according to an embodiment of the present invention;

fig. 2 is a flow chart of a high alkalinity concentrated brine zero emission treatment method according to an embodiment of the present invention.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

As shown in fig. 1, the system for zero-emission treatment of high-alkalinity concentrated brine according to an embodiment of the present invention is used for zero-emission treatment of sodium carbonate and sodium chloride type concentrated brine, and may include an evaporation concentration device 10, a sodium carbonate monohydrate evaporation crystallization device 20, a sodium carbonate decahydrate freezing crystallization device 30, a sodium chloride evaporation crystallization device 40, and a miscellaneous salt drying device 50, which are connected in sequence.

The evaporation concentration device 10 performs preheating concentration treatment on the strong brine to obtain a concentrated solution. The sodium carbonate monohydrate evaporation crystallization device 20 performs sodium carbonate monohydrate extraction on the concentrated solution to obtain sodium carbonate monohydrate mother liquor and sodium carbonate monohydrate product salt. The sodium carbonate decahydrate freezing and crystallizing device 30 performs freezing crystallization and hot melting treatment on the sodium carbonate monohydrate mother liquor to obtain frozen mother liquor and hot-melted sodium carbonate monohydrate slurry. And the sodium chloride evaporation crystallization device 40 is used for extracting sodium chloride from the frozen mother liquor to obtain sodium chloride mother liquor and sodium chloride product salt. The mixed salt drying device 50 is used for drying the mother liquor (part or all) produced by the sodium chloride evaporative crystallization device 40 to obtain mixed salt.

Wherein, the evaporation concentration device 10 can comprise an evaporation raw water pool 11, a first preheater 12 and an evaporation concentration unit 13 which are connected in sequence; the evaporation concentration device 10 is connected with a sodium carbonate monohydrate evaporation crystallization device 20 through an evaporation concentration unit 13. The raw water evaporation pool 11 is used for receiving and storing strong brine, the strong brine is conveyed from the raw water evaporation pool 11 to the first preheater 12 for preheating treatment, and the preheated strong brine is conveyed to the evaporation concentration unit 13 for evaporation concentration treatment to obtain concentrated solution of high-concentration sodium carbonate and sodium chloride. The concentrate has dissolved solids (TDS) of no less than 220000 mg/L.

The heat source for the first preheater 12 may be primarily from condensed water in the process system, with a small amount from the low pressure saturated steam at the plant area. The condensed water comprises the evaporated condensed water generated by the evaporative concentration unit 13, the sodium carbonate monohydrate evaporative crystallization device 20 and the sodium chloride evaporative crystallization device 40, and is guided to the preheating treatment, so that the heat is recycled, and the energy consumption is reduced. The evaporation concentration unit 13 can adopt a mechanical compression evaporation (MVR) falling film evaporation concentration tank or a multi-effect evaporation (MED) forced circulation concentration tank.

The sodium carbonate monohydrate evaporative crystallization device 20 comprises a sodium carbonate monohydrate evaporative crystallization tank 21, a first thickener 22, a first centrifuge 23 and a first dryer 24 which are connected in sequence. The sodium carbonate monohydrate evaporative crystallization tank 21 is connected with the evaporative concentration unit 13 of the evaporative concentration device 10 and receives the concentrated solution from the evaporative concentration device 10. The concentrated solution is processed by evaporation and crystallization at 90-100 ℃ in a sodium carbonate monohydrate evaporation and crystallization tank 21 to form sodium carbonate monohydrate mother liquor and sodium carbonate monohydrate slurry. The sodium carbonate monohydrate slurry is subjected to thickening treatment by a first thickener 22, centrifugal treatment by a first centrifuge 23 and drying treatment by a first dryer 24 in sequence to obtain sodium carbonate monohydrate product salt.

The sodium carbonate monohydrate evaporative crystallization apparatus 20 may further include a first packaging machine 25 for packaging the dried sodium carbonate monohydrate product salt, as necessary.

The sodium carbonate decahydrate freezing and crystallizing device 30 receives sodium carbonate monohydrate mother liquor from the sodium carbonate monohydrate evaporative crystallizing tank 21, and carries out freezing crystallization and hot melting treatment on the sodium carbonate monohydrate mother liquor. Specifically, the sodium carbonate decahydrate freezing and crystallizing device 30 comprises a freezing and crystallizing tank 31, a second thickener 32, a second centrifuge 33 and a hot melting tank 34 which are connected in sequence. The freezing and crystallizing tank 31 is connected with the sodium carbonate monohydrate evaporative crystallizing tank 21 and receives mother liquor (namely the sodium carbonate monohydrate mother liquor) from the sodium carbonate monohydrate evaporative crystallizing tank 21, and the sodium carbonate monohydrate mother liquor is frozen and crystallized at the temperature of-2-0 ℃ to form freezing mother liquor and sodium carbonate decahydrate slurry. The sodium carbonate decahydrate slurry is subjected to thickening and crystal growth treatment by the second thickener 32 and centrifugal separation by the second centrifuge 33 in this order to obtain a sodium carbonate decahydrate slurry. And then the sodium carbonate decahydrate slurry is conveyed into a hot melting tank 34 for hot melting treatment to obtain sodium carbonate monohydrate slurry.

The hot melt tank 34 is also connected with the first thickener 22, so that the hot-melted sodium carbonate monohydrate slurry is conveyed to the first thickener 22, and then thickening, centrifuging and drying treatment are carried out to form sodium carbonate monohydrate product salt.

The sodium chloride evaporative crystallization apparatus 40 receives the frozen mother liquor from the freezing crystallization tank 31 and extracts sodium chloride from the frozen mother liquor. The sodium chloride evaporative crystallization apparatus 40 may include a sodium chloride evaporative crystallization tank 41, a third thickener 42, a third centrifuge 43, and a third dryer 44, which are connected in sequence. The sodium chloride evaporative crystallization tank 41 is connected to the freezing crystallization tank 31 and receives the frozen mother liquor from the freezing crystallization tank 31.

The frozen mother liquor is preferably preheated and then is subjected to evaporative crystallization at 25-40 ℃ in a sodium chloride evaporative crystallization tank 41 to obtain sodium chloride mother liquor and sodium chloride slurry. The sodium chloride slurry is subjected to thickening and crystal growth treatment by a third thickener 42, centrifugal separation treatment by a third centrifuge 43 and drying treatment by a third dryer 44 in sequence to obtain sodium chloride product salt.

In order to realize the preheating treatment of the freezing mother liquor, the sodium carbonate decahydrate freezing and crystallizing device 30 can further comprise a second preheater 35 connected between the freezing and crystallizing tank 31 and the sodium chloride evaporating and crystallizing tank 41, and the freezing mother liquor output from the freezing and crystallizing tank 31 enters the sodium chloride evaporating and crystallizing tank 41 after being preheated by the second preheater 35.

The sodium chloride evaporative crystallization apparatus 40 may further include a second packaging machine 45 for packaging the dried sodium chloride product salt, as necessary.

The mixed salt drying device 50 is connected with the sodium chloride evaporation crystallizing tank 41 of the sodium chloride evaporation crystallizing device 40, receives partial or all sodium chloride mother liquor, and then carries out drying treatment on the sodium chloride mother liquor to obtain mixed salt with mixed components.

Preferably, the sodium chloride evaporative crystallization device 40 is further connected to the raw water evaporation tank 11, so that most of the sodium chloride mother liquor is refluxed to the raw water evaporation tank 11, and a small part of the sodium chloride mother liquor is sent to the miscellaneous salt drying device 50 for drying treatment.

The salt drying device 50 may comprise a drum dryer or a rake dryer.

With reference to fig. 1 and 2, the high-alkalinity strong brine zero-discharge treatment method of the present invention is implemented by using the high-alkalinity strong brine zero-discharge treatment system, and the high-alkalinity strong brine zero-discharge treatment method may include the following steps:

s1, sequentially carrying out preheating treatment and evaporation concentration treatment on the concentrated brine to obtain concentrated solution of high-concentration sodium carbonate and sodium chloride.

This step S1 is performed in the evaporation concentration apparatus 10. In the evaporation concentration device 10, the strong brine is firstly stored in the evaporation raw water tank 11, the strong brine is conveyed from the evaporation raw water tank 11 to the first preheater 12, preheating treatment is carried out in the first preheater 12, and the preheated strong brine is conveyed to the evaporation concentration unit 13 for evaporation concentration treatment, so that concentrated solution of high-concentration sodium carbonate and sodium chloride is obtained. The concentrate has dissolved solids (TDS) of no less than 220000 mg/L.

S2, carrying out sodium carbonate monohydrate evaporation crystallization treatment on the concentrated solution to obtain sodium carbonate monohydrate mother liquor and sodium carbonate monohydrate product salt.

The concentrated solution obtained in step S1 is sent to the sodium carbonate monohydrate evaporative crystallization device 20. In a sodium carbonate monohydrate evaporation crystallization device 20, the concentrated solution is subjected to evaporation crystallization treatment at 90-100 ℃ in a sodium carbonate monohydrate evaporation crystallization tank 21 to form a sodium carbonate monohydrate mother solution and a sodium carbonate monohydrate slurry; the sodium carbonate monohydrate slurry is subjected to thickening treatment by a first thickener 22, centrifugal treatment by a first centrifuge 23 and drying treatment by a first dryer 24 in sequence to obtain sodium carbonate monohydrate product salt.

The sodium carbonate monohydrate product salt may be further packaged by a first packaging machine 25.

S3, carrying out freezing crystallization treatment and hot melting treatment on the sodium carbonate monohydrate mother liquor to obtain frozen mother liquor and hot-melted sodium carbonate monohydrate slurry.

Specifically, the mother liquor of sodium carbonate monohydrate is transferred from the sodium carbonate monohydrate evaporative crystallization tank 21 to the sodium carbonate decahydrate freeze crystallization device 30. The freezing crystallization tank 31 of the sodium carbonate decahydrate freezing crystallization device 30 receives sodium carbonate monohydrate mother liquor from the sodium carbonate monohydrate evaporation crystallization tank 21, and the sodium carbonate monohydrate mother liquor is frozen and crystallized at the temperature of-2-0 ℃ to form freezing mother liquor and sodium carbonate decahydrate slurry. The sodium carbonate decahydrate slurry is subjected to thickening and crystal growth treatment by the second thickener 32 and centrifugal separation by the second centrifuge 33 in this order to obtain a sodium carbonate decahydrate slurry. And then the sodium carbonate decahydrate slurry is conveyed into a hot melting tank 34 for hot melting treatment to obtain sodium carbonate monohydrate slurry.

The hot melted sodium carbonate monohydrate slurry is then transferred to the first thickener 22 for further thickening, centrifugation and drying in sequence to form the sodium carbonate monohydrate product salt.

S4, carrying out sodium chloride evaporation crystallization treatment on the frozen mother liquor to obtain sodium chloride mother liquor and sodium chloride product salt.

Wherein, the sodium chloride evaporative crystallization device 40 receives the frozen mother liquor from the freezing crystallization tank 31. And (3) carrying out evaporative crystallization at 25-40 ℃ on the frozen mother liquor in a sodium chloride evaporative crystallization tank 41 of a sodium chloride evaporative crystallization device 40 to obtain sodium chloride mother liquor and sodium chloride slurry. The sodium chloride slurry is subjected to thickening and crystal growth treatment by a third thickener 42, centrifugal separation treatment by a third centrifuge 43 and drying treatment by a third dryer 44 in sequence to obtain sodium chloride product salt. The sodium chloride product salt may then be packaged in a second packaging machine 45.

The frozen mother liquor is preheated by the second preheater 35 before entering the sodium chloride evaporative crystallization tank 41.

S5, drying part or all of the sodium chloride mother liquor obtained in the step S4 to obtain mixed salt.

Preferably, a small amount of sodium chloride mother liquor is dried, and most of the sodium chloride mother liquor is returned to the raw water evaporation tank 11. The drying treatment is realized by a miscellaneous salt drying device 50, and the miscellaneous salt drying device 50 can comprise a roller dryer or a rake dryer.

In conclusion, after the strong brine is treated by the treatment system or the treatment method, the strong brine can be recycled, sodium carbonate monohydrate and sodium chloride which meet the national standard are obtained, the water recovery rate of the wastewater is greatly improved, the environment is protected, the crystallized salt is recycled, and the zero emission target of the strong brine is really realized.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.