WO2020125285A1

WO2020125285A1 - Salt extraction apparatus for high-salinity waste water and salt extraction method

Info

Publication number: WO2020125285A1
Application number: PCT/CN2019/118454
Authority: WO
Inventors: 陈建军; 张柯; 王慧丽
Original assignee: 苏州清然环保科技有限公司; 陕西创净环保科技有限责任公司
Priority date: 2018-12-18
Filing date: 2019-11-14
Publication date: 2020-06-25
Also published as: CN110590002A

Abstract

A salt extraction method for high-salinity waste water, which comprises: mixing high-salinity waste water and an organic solvent such that an inorganic salt which does not dissolve in an organic solvent is precipitated from the high-salinity waste water to form a solid-liquid mixture; performing solid-liquid separation on the solid-liquid mixture to obtain solid-phase inorganic salt and low-salinity waste water. The solid-liquid inorganic salt separated by using the present method is fluffy and does not harden and will not cause sewage blockage. Further disclosed is a salt extraction apparatus for high-salinity waste water.

Description

Salt precipitation device and salt precipitation method for high-salt wastewater

This application requires the priority of the Chinese patent application with the filing date of December 18, 2018, the application number of 201811549329.8, and the invention titled "Salt Separation Device and Salt Separation Method for High-Salt Wastewater", the entire contents of which are incorporated by reference in In this application.

Technical field

The invention belongs to the technical field of wastewater treatment, and relates to a salt precipitation device and a salt precipitation method for high-salt wastewater.

Background technique

The problem of water pollution is an environmental problem throughout the world. In order to improve the quality of the water environment, the country’s water environmental protection measures have been increasingly strengthened. "Zero discharge" has become one of the most important issues in wastewater treatment. The so-called "zero discharge" is usually It can be understood as reducing pollutant and resource emissions to zero to an infinite extent. For high-salt wastewater generated in industrial fields such as chemical industry, printing and dyeing, and medicine, effectively recovering a large amount of electrolyte resources in wastewater to obtain inorganic salt products is an important task to achieve "zero emissions."

At present, in the treatment of high-salt wastewater, common salt precipitation technologies include membrane technology and multi-effect evaporation technology. Among them: although the membrane technology can effectively separate the inorganic salt electrolyte in the wastewater, it has high energy consumption, easy fouling, and operation. Disadvantages such as large cost; multi-effect evaporation technology has the disadvantages of high energy consumption, easy fouling, and large operating cost, and for wastewater containing a variety of inorganic salt electrolytes with similar solubility, multi-effect evaporation technology is often difficult to achieve The inorganic salt electrolyte is effectively separated, and high-purity inorganic salt products cannot be obtained.

Summary of the invention

The object of the present invention is to provide a salt precipitation device and a salt precipitation method for high-salt wastewater to solve at least one of the problems of the existing salt precipitation technology, such as high energy consumption, easy fouling, and large operating costs.

To achieve one of the above objectives, an embodiment of the present invention provides a salt precipitation method for high-salt wastewater, the salt precipitation method includes a salt precipitation step and a separation step, wherein,

The salt precipitation step is: mixing high-salt wastewater and an organic solvent, so that inorganic salts insoluble in the organic solvent are precipitated from the high-salt wastewater to form a solid-liquid mixture;

The separation step is: the solid-liquid mixture is subjected to solid-liquid separation to obtain solid-phase inorganic salts and low-salt wastewater.

As a further improvement of an embodiment of the present invention, the organic solvent is an organic substance; for high-salt wastewater, several cycles are sequentially processed according to the salt-out step and the separation step, and any two cycles of the The organic solvent in the salt step is different.

As a further improvement of an embodiment of the present invention, the organic solvent is a mixture of two or more organic substances.

As a further improvement of an embodiment of the present invention, the organic substance is an alcohol-based organic substance or an amine-based organic substance.

As a further improvement of an embodiment of the present invention, in the separation step, any one of filtration, suction filtration, and centrifugation is used to separate the solid-liquid mixture.

As a further improvement of an embodiment of the present invention, in the salting-out step, the high-salt wastewater and the organic solvent are mixed evenly by stirring.

To achieve one of the above objectives, an embodiment of the present invention also provides a salting device for high-salt wastewater, the salting device includes a reaction kettle, and a mixing zone is arranged in the reaction kettle and is located below the mixing zone In the separation zone, the reaction kettle is provided with a water inlet capable of introducing high-salt wastewater and a liquid inlet capable of introducing an organic solvent in the mixing zone. The high-salt wastewater and the organic solvent are mixed in the mixing zone and A solid-liquid mixture is formed. The reaction kettle is provided with a salt discharge port below the separation zone, and the salt discharge port can discharge the solid-phase inorganic salt separated from the solid-liquid mixture out of the reaction kettle. The upper part of the kettle is also provided with a drain port.

As a further improvement of an embodiment of the present invention, the salt precipitation device further includes a stirring structure provided in the mixing zone; the water inlet is opened at the top of the mixing zone and the liquid inlet is opened in the The bottom of the mixing zone.

As a further improvement of an embodiment of the present invention, the inner wall of the reaction kettle is provided in a funnel shape in the separation zone.

As a further improvement of an embodiment of the present invention, a settling zone located above the mixing zone is also arranged in the reaction kettle, and the salt precipitation device further includes a three-phase separator disposed in the settling zone.

Compared with the prior art, the beneficial effects of the present invention are: mixing high-salt wastewater with an organic solvent, using organic solvent crystallization separation technology to perform salt precipitation treatment on high-salt wastewater, not only can effectively separate the inorganic salt electrolyte in the wastewater The solid inorganic salt separated is grit-shaped and fluffy without compaction, so it will not cause fouling, and has low energy consumption and low operating cost.

BRIEF DESCRIPTION

1 is a schematic structural diagram of a salt precipitation device for high-salt wastewater according to an embodiment of the present invention;

2 is a flowchart of a salting-out method of high-salt wastewater according to an embodiment of the present invention.

detailed description

The present invention will be described in detail below with reference to specific embodiments shown in the drawings. However, these embodiments do not limit the present invention, and structural, method, or functional changes made by those of ordinary skill in the art according to these embodiments are included in the protection scope of the present invention.

As shown in FIG. 1, an embodiment of the present invention provides a salt precipitation device 100 which is applied to a salt precipitation treatment project of high-salt waste water, and is also referred to as a salt precipitation device 100 of high-salt wastewater.

The salt precipitation device 100 includes a reactor 1 placed vertically, and a mixing zone 12 and a separation zone 13 are arranged in the reactor 1.

Among them, the reaction kettle 1 is provided with a water inlet 2 capable of introducing high-salt wastewater (that is, waste water to be treated) and a liquid inlet 3 capable of introducing organic solvent in the mixing zone 12, that is, the high-salt wastewater can pass through the water inlet 2 After passing through the side wall of the reaction kettle 1, it directly enters the mixing zone 12, and the organic solvent can directly enter the mixing zone 12 after passing through the side wall of the reaction kettle 1 through the liquid inlet 3. In this way, the high-salt wastewater and the organic solvent are mixed in the mixing zone 12 so that inorganic salts insoluble in the organic solvent are precipitated from the wastewater to form a solid-liquid mixture, thereby completing the salt precipitation step in the salt precipitation treatment process of the high-salt wastewater.

The separation zone 13 is located below the mixing zone 12 and can be used to separate solid phase inorganic salts from the solid-liquid mixture in the mixing zone 12. The reaction kettle 1 is provided with a salt discharge port 4 below the separation zone 13, and the salt discharge port 4 can discharge the solid phase inorganic salt out of the reaction kettle 1, that is, the solid phase inorganic salt passes through the salt discharge port 4 below the separation zone 13 Discharge. In this embodiment, the solid inorganic salt discharged from the salt discharge port 4 is in a wet salt state. After being discharged outside the reactor 1, the moisture and/or organic solvent on the wet salt can be removed by drying or other technical means . The upper part of the reaction kettle 1 is also provided with a drainage port 5, so that the liquid-phase low-salt wastewater in the solid-liquid mixture in the mixing zone 12 (that is, the mixture of the wastewater and the organic solvent after the precipitation of the inorganic salt) is discharged from the drainage port 5 for reaction Outside Kettle 1.

In this way, the salt precipitation device 100 of the present embodiment mixes the high-salt wastewater and the organic solvent in the mixing zone 12, uses the organic solvent crystallization separation technology to perform salt precipitation treatment on the high-salt wastewater, and provides the mixing zone 12 and In the separation zone 13, the salt precipitation step and the separation step can be completed in the same reaction kettle 1, which not only can effectively separate the inorganic salt electrolyte in the wastewater, the solid phase inorganic salt is separated into a gravel shape, and it is not fluffy. No salt clogging of the salt outlet 4 will be caused, and the equipment is simple and convenient to operate, low energy consumption, and low operating cost.

Wherein, the organic solvent may be an organic substance or a mixture of two or more organic substances according to production requirements.

For example, the organic solvent is an organic substance, that is, the organic solvent has a single component, and when the high-salt wastewater contains only a single inorganic salt, or when the high-salt wastewater contains at least two inorganic salts, this can be used The specific inorganic salts insoluble in the organic matter in the high-salt wastewater are separated out and separated and discharged out of the reaction kettle 1 through the separation zone 13, thereby obtaining a high-purity solid-phase inorganic salt product. A specific example is used to illustrate. For example, when the high-salt wastewater contains inorganic salt A and inorganic salt B, two salt-out devices 100 may be provided. The drain port 5 of the previous salt-out device 100 communicates with the salt-out device 100 after Water inlet 2, the organic solvent introduced at the liquid inlet 3 of the previous salting-out device 100 is the first organic substance a, so that the inorganic salt A is precipitated in the previous salting-out device 100; The low-salt wastewater (containing wastewater and first organic matter a) discharged from the drain 5 continues to be introduced into the reaction kettle 1 of the latter salt-out device 100 as high-salt wastewater, and is introduced at the liquid inlet 3 of the latter salt-out device 100 The organic solvent is the second organic substance b, so that the inorganic salt B is precipitated in the latter salt-out device 100, so that the inorganic salt A and the inorganic salt B in the high-salt wastewater can be effectively separated.

For another example, when the high-salt wastewater contains only a single inorganic salt, or when the high-salt wastewater contains at least two inorganic salts without the need to separate different inorganic salts, the organic solvent is two or more organic substances The mixture is formed so that all/most of the inorganic salts in the high-salt wastewater are precipitated together and separated and discharged out of the reaction kettle 1 through the separation zone 13.

In addition, the organic substance may be an alcohol-based organic substance such as methanol or ethanol, or an amine-based organic substance.

Further, the salt precipitation device 100 further includes a stirring structure 6 provided in the mixing zone 12, so that the high-salt wastewater introduced from the water inlet 2 and the organic solvent introduced from the liquid inlet 3 can be fully mixed in the mixing zone 12, In order to facilitate the analysis of inorganic salts insoluble in organic solvents in high-salt wastewater. In this embodiment, the stirring structure 6 can be fixed on the wall of the reaction kettle 1 by a bracket and the effective stirring range of the stirring device 6 runs through the entire mixing zone 12.

Preferably, in this embodiment, the water inlet 2 is opened at the top of the mixing zone 12, that is, the wastewater directly enters the top of the mixing zone 12 through the water inlet 2, of course, by setting a control valve and/or a power pump to Control whether high-salt wastewater is introduced into the water inlet 2; the liquid inlet 3 is opened at the bottom of the mixing zone 12, that is, the organic solvent directly enters the bottom of the mixing zone 12 through the liquid inlet 3, of course, by setting a control valve and/ Or power pump to control whether the inlet 3 introduces organic solvent. In this way, due to the difference in density, the high-salt wastewater has a tendency to sink relative to the organic solvent. In other words, the organic solvent has an upward trend relative to the high-salt wastewater. The layout of the inlet 2 and the inlet 3 is beneficial to the high-salt wastewater Repeat contact with organic solvent and mix.

Among them, the top of the stirring structure 6 is higher than the water inlet 2, that is, the effective stirring range of the stirring structure 6 is higher than the water inlet 2; at the same time, the bottom end of the stirring structure 6 is lower than the liquid inlet 3, that is, the stirring structure The effective stirring range of 6 is lower than that of the liquid inlet 3, so that the mixing area 12 between the water inlet 2 and the liquid inlet 3 is covered by the effective stirring range of the stirring structure 6.

Further, in this embodiment, the salt precipitation device 100 realizes the filtration and separation of the solid-liquid mixture in the separation zone 13, that is, the inner wall of the reaction kettle 1 is provided with a funnel structure at the separation zone 13, and the salt discharge port 4 is formed The opening of the tip of the lower part of the funnel structure, so that after the solid-liquid mixture formed in the mixing zone 12 enters the separation zone 13 and loses the agitation of the stirring structure 6, the solid phase inorganic salt therein is deposited in the separation under the action of its own gravity Below the zone 13, it is discharged from the reactor 1 through the salt discharge port 4 to complete the filtration and separation. Of course, it is not limited to this. For example, in other embodiments, the salt precipitation device 100 may further include a suction filtration structure provided at the separation zone 13 to achieve suction filtration separation of the solid-liquid mixture, or include the separation zone 13 To achieve centrifugal separation of solid-liquid mixture.

Further, a settling zone 11 located above the mixing zone 12 is arranged in the reaction kettle 1, and a drain 5 is located at the top of the settling zone 11; the salt precipitation device 100 further includes a three-phase separator 7 disposed in the settling zone 11 and a drain 5 is located above the three-phase separator 7. During use, when the solid-liquid mixture entrained with particulate solid-phase inorganic material flows upward to the sedimentation zone 11, under the separation effect of the three-phase separator 7, the solid-phase inorganic substance falls back to the mixing zone 12, while the liquid phase Continue to ascend to the top of the settling zone 11 and drain out of the reactor 1 through the drain 5. Through the three-phase separator 7, it can be ensured that the low-salt wastewater discharged from the drain 5 does not contain solid-phase inorganic substances.

It can be understood that, in this embodiment, the settlement zone 11, the mixing zone 12, and the separation zone 13 are roughly divided according to the treatment effect achieved in the space of different height ranges in the reactor 1, for example, the mixing zone 12 is roughly a stirring structure 6 The height range covered by the separation zone 13 is roughly the height range of the funnel structure; in fact, the settlement zone 11, the mixing zone 12, and the separation zone 13 are connected to each other as a whole and between two adjacent (that is, settlement There is no obvious dividing line or barrier structure between the zone 11 and the mixing zone 12 and between the mixing zone 12 and the separation zone 13).

In addition, the salt precipitation device 100 may further include a recovery structure whose input port is connected to the drain port 5 for receiving low-salt wastewater from the drain port 5, and the recovery structure can be extracted from this by means of extraction, distillation, etc. The organic solvent is recovered from the low-salt wastewater, and the output port of the recovery structure is connected to the liquid inlet 3 to deliver the recovered organic solvent to the liquid inlet 3, thereby achieving the reuse of the organic solvent.

Further, referring to FIG. 2, an embodiment of the present invention also provides a salt precipitation method for high-salt wastewater. The salt precipitation method may be implemented using the salt precipitation device shown in FIG. 1. Specifically, the salt precipitation method includes Salt precipitation step and separation step. Wherein, the salt precipitation step is: mixing high-salt wastewater and an organic solvent, so that inorganic salts insoluble in the organic solvent are precipitated from the high salt wastewater to form a solid-liquid mixture; the separation step is: separating the solid-liquid The mixture is subjected to solid-liquid separation to obtain solid-phase inorganic salts and low-salt wastewater.

In this way, the salting-out method of the high-salt wastewater of the present embodiment mixes the high-salt wastewater with an organic solvent and uses the organic solvent crystallization separation technology to perform salting-out treatment on the high-salt wastewater, which not only can effectively separate the inorganics in the high-salt wastewater In the salt electrolyte, the solid inorganic salt separated is in the form of gravel, fluffy and not compacted, so that it will not cause fouling, and has low energy consumption and low operating cost.

Wherein, the organic solvent is an organic substance, that is, the organic solvent has a single component. In this way, the high-salt wastewater can be treated in a cycle according to the salt-out step and the separation step in order to make the high-salt wastewater The specific inorganic salts insoluble in the organic matter are precipitated out, thereby obtaining a high-purity solid-phase inorganic salt product.

If the organic solvent is an organic substance, high-salt wastewater can also be treated in sequence according to the salting step and the separating step for several cycles, and the organic solvent in the salting step for any two cycles is different At this time, for high-salt wastewater with several kinds of inorganic salts, high-purity solid-phase inorganic salt products can be obtained after each cycle is completed, thereby effectively separating several kinds of inorganic salts in high-salt wastewater. For example, when the high-salt wastewater contains inorganic salt A and inorganic salt B, the first cycle of the high-salt wastewater can be processed in sequence according to the salting step and the separation step, and the In the salt step, the first organic matter a is added to obtain the solid-phase inorganic salt A insoluble in the first organic matter a and the low-salt wastewater containing the first organic matter a; The separation step sequentially processes the second cycle, and the second organic substance b is added to the salt precipitation step of the second cycle to precipitate the inorganic salt B insoluble in the second organic substance b.

Of course, it is not limited to the embodiment in which the organic solvent is an organic substance, for example, when the high-salt wastewater contains only a single inorganic salt, or the high-salt wastewater contains at least two inorganic salts without the need to separate different inorganic salts At this time, the high-salt wastewater can only be processed in one cycle in accordance with the salt-out step and the separation step, and in this cycle, the organic solvent is a mixture of two or more organic substances to make the high-salt wastewater All/most of inorganic salts in the wastewater are precipitated together.

Further, in the salting-out step, the wastewater and the organic solvent are mixed evenly by stirring.

Further, in the separation step, the solid-liquid mixture is subjected to solid-liquid separation by any one of filtration, suction filtration, and centrifugation.

In addition, the salting-out method further includes a recycling step, and the recycling step includes: recycling and reusing organic solvent of the low-salt wastewater obtained in the separation step. It is understandable that the low-salt wastewater obtained in the separation step includes wastewater and organic solvents, and the organic solvent can be recovered from the low-salt wastewater obtained in the separation step through distillation, extraction and other processes, and the organic solvent is reused In the salting-out step.

In the following, the salt precipitation method of the present invention is introduced through specific experimental examples.

Example 1

In this embodiment, for the production wastewater of a petrochemical enterprise, the wastewater has a salt content of 30%-60% before treatment, and the wastewater is treated by the salt precipitation method: the wastewater and the alcohol organic matter are stirred While mixing, a solid-liquid mixture is obtained; the solid-liquid mixture is centrifuged to obtain a solid-phase inorganic salt and effluent.

Through testing, the salt content of the effluent is less than 1%. It can be seen that the salt precipitation method of the present invention can effectively precipitate the inorganic salts in the wastewater, and has low energy consumption, no pollution and operating costs small.

Example 2

In this embodiment, for the production wastewater of a pesticide company, the wastewater has a salt content of 20%-40% before treatment, and the wastewater is treated by the salt precipitation method: the wastewater and the alcohol organic matter are stirred While mixing, a solid-liquid mixture is obtained; the solid-liquid mixture is centrifuged to obtain a solid-phase inorganic salt and effluent.

It should be understood that although this specification is described according to embodiments, not every embodiment includes only an independent technical solution. This description of the specification is for clarity only, and those skilled in the art should treat the specification as a whole, each The technical solutions in the embodiments may also be combined appropriately to form other embodiments that can be understood by those skilled in the art.

The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention, they are not intended to limit the scope of protection of the present invention, and equivalent embodiments or technical equivalents made without departing from the technical spirit of the present invention Changes should be included in the protection scope of the present invention.

Claims

A salt precipitation method for high-salt wastewater, characterized in that the salt precipitation method includes a salt precipitation step and a separation step, wherein,

The salt precipitation step is: mixing high-salt wastewater and an organic solvent, so that inorganic salts insoluble in the organic solvent are precipitated from the high-salt wastewater to form a solid-liquid mixture;

The separation step is: the solid-liquid mixture is subjected to solid-liquid separation to obtain solid-phase inorganic salts and low-salt wastewater.
The salting-out method of high-salt wastewater according to claim 1, characterized in that the organic solvent is an organic substance; for high-salt wastewater, several cycles are sequentially processed according to the salting-out step and the separating step, And the organic solvent in the salting-out step of any two cycles is different.
The salting-out method of high-salt wastewater according to claim 1, wherein the organic solvent is a mixture of two or more organic substances.
The salting-out method of high-salt wastewater according to claim 2, wherein the organic substance is an alcohol-based organic substance or an amine-based organic substance.
The salt precipitation method for high-salt wastewater according to claim 1, wherein in the separation step, any one of filtration, suction filtration, and centrifugation is used to separate the solid-liquid mixture.
The salting-out method of high-salt wastewater according to claim 1, wherein in the salting-out step, the high-salt wastewater and the organic solvent are uniformly mixed by stirring.
A salt precipitation device for high-salt wastewater, characterized in that the salt precipitation device includes a reaction kettle, and a mixing zone and a separation zone located below the mixing zone are arranged in the reaction kettle. The mixing zone is provided with a water inlet capable of introducing high-salt wastewater and a liquid inlet capable of introducing an organic solvent. The high-salt wastewater and the organic solvent are mixed in the mixing zone to form a solid-liquid mixture. A salt discharge port is opened below the separation zone, and the salt discharge port can discharge the solid-phase inorganic salt separated from the solid-liquid mixture out of the reaction kettle, and a drain port is also opened in the upper part of the reaction kettle.
The salt precipitation device for high-salt wastewater according to claim 7, characterized in that the salt precipitation device further comprises a stirring structure provided in the mixing zone; the water inlet is opened at the top of the mixing zone and The liquid inlet is opened at the bottom of the mixing zone.
The salt precipitation device for high-salt wastewater according to claim 7, wherein the inner wall of the reaction kettle is provided in a funnel shape in the separation zone.
The salt precipitation device for high-salt wastewater according to claim 7, wherein a sedimentation zone located above the mixing zone is further arranged in the reaction kettle, and the salt precipitation device further includes a sedimentation zone disposed in the sedimentation zone Three-phase separator.