Zero-discharge recycling device for high-salinity wastewater with sodium chloride as main component
By designing a zero-emission recycling device for high-salt wastewater from sodium chloride, the problem of how to effectively use this wastewater to produce sodium bicarbonate is solved, and efficient resource recycling and environmental protection goals are achieved.
Patent Information
- Application Number
- CN202422133364.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-30
- Publication Date
- 2025-06-24
- Estimated Expiration
- 2034-08-30
AI Technical Summary
How to use sodium chloride high-salt wastewater to produce sodium bicarbonate, increase the added value of by-products ammonium chloride and sodium chloride, and achieve zero wastewater discharge.
A zero-emission recycling and utilization device was designed to achieve the recycling and utilization of sodium bicarbonate, ammonium chloride and sodium chloride through steps such as high-salt wastewater concentration, metathesis reaction, evaporation concentration and cold crystallization.
The recycling of high-purity sodium bicarbonate, ammonium chloride and sodium chloride has been achieved, the utilization rate of resources has been improved, production costs have been reduced, and the goal of zero emissions has been achieved.
Smart Images
Figure CN223016680U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of water treatment, and particularly relates to a zero-emission recycling device for high-salt wastewater mainly composed of sodium chloride. Background Art
[0002] A large amount of high-concentration mixed-salt wastewater is generated in the production of the coal chemical industry. Generally, it contains a large amount of inorganic salts formed by fluorine, chlorine, sulfate radicals, etc., and the components are complex. If it is discharged without treatment in large quantities, it will not only cause waste of some resources, but also seriously affect industrial production safety, and at the same time cause damage to the ecological environment.
[0003] At present, the simplest and most direct way to treat mixed-salt wastewater is to carry out evaporation concentration and crystallization, and the obtained mixed-salt solid is treated by direct landfill or other solid waste treatment methods. The low-value mixed salt obtained by this method has low resource utilization value, and direct landfill also causes waste of resources. The idea of purification and reuse generally adopts the process route of "defluorination + nanofiltration + freezing or evaporation crystallization". For high-salt wastewater mainly composed of sodium chloride and sodium sulfate, after being treated by a nanofiltration membrane for salt separation, a single high-salt wastewater pretreatment liquid can be obtained. However, direct discharge of such wastewater will also cause environmental pollution, such as aggravating land salinization. It is necessary to recycle its salt content. At present, the operating cost of the wastewater treatment process is still relatively high, and it cannot completely and effectively remove soluble salts, failing to achieve the purpose of energy conservation and emission reduction.
[0004] At present, the main methods for preparing sodium bicarbonate from sodium chloride are the ammonia-soda method and the combined soda-making method, in which ammonia gas and carbon dioxide are introduced into a saturated sodium chloride solution for reaction. There is also a method of preparing sodium bicarbonate by the metathesis reaction of ammonium bicarbonate and sodium chloride. After the mother liquor is deammoniated, ammonium bicarbonate and sodium chloride are recovered by concentration to obtain agricultural ammonium chloride. However, the conversion rate of sodium chloride in this method is not high, and the resulting high-ammonium wastewater has nowhere to be discharged, affecting environmental protection.
[0005] At present, the recovery of ammonium chloride usually adopts the freezing method, and the mother liquor after separating sodium bicarbonate is directly cooled to precipitate ammonium chloride. This method not only has a low recovery rate of ammonium chloride, but also has a low purity.
[0006] Therefore, how to produce sodium bicarbonate from high-salt sodium chloride wastewater, increase the added value of by-products ammonium chloride and sodium chloride, and achieve zero discharge of wastewater has become an urgent problem to be solved in the current field. Content of the Utility Model
[0007] The utility model provides a zero-emission recycling device for high-salt wastewater mainly composed of sodium chloride to solve the problem of the recovery of sodium chloride in high-salt wastewater. The purpose of the utility model is achieved through the following technical solutions.
[0008] A zero-emission recycling device for high-salt wastewater mainly composed of sodium chloride, comprising:
[0009] A high-salt wastewater concentration device for concentrating high-salt wastewater;
[0010] A reactor for reacting the concentrated high-salt wastewater with ammonium bicarbonate; the reactor is provided with a first solid-liquid separator, and the first solid-liquid separator is used for solid-liquid separation of the reacted high-salt wastewater to obtain mother liquor I and sodium bicarbonate solid;
[0011] A first evaporation and concentration device for evaporating and concentrating mother liquor I;
[0012] A first cooling and crystallization device for cooling the evaporated and concentrated mother liquor I; the first cooling and crystallization device is provided with a second solid-liquid separator, and the second solid-liquid separator is used for solid-liquid separation of the cooled mother liquor I to obtain mother liquor II and ammonium chloride solid;
[0013] A second evaporation and concentration device for evaporating and concentrating mother liquor II; the second evaporation and concentration device is provided with a third solid-liquid separator, and the third solid-liquid separator is used for solid-liquid separation of the evaporated and concentrated mother liquor II to obtain mother liquor III and sodium chloride solid;
[0014] A second cooling and crystallization device for cooling the evaporated and concentrated mother liquor III; the second cooling and crystallization device is provided with a fourth solid-liquid separator, and the fourth solid-liquid separator is used for solid-liquid separation of the cooled mother liquor III to obtain mother liquor IV and ammonium chloride solid; the mother liquor IV returns to the second evaporation and concentration device for evaporation and concentration.
[0015] Optionally, the reactor is a double decomposition reaction kettle.
[0016] Optionally, the reactor is a double decomposition reaction kettle.
[0017] Optionally, the first evaporation and concentration device and the second evaporation and concentration device adopt atmospheric evaporators.
[0018] Optionally, the first cooling and crystallization device and the second cooling and crystallization device adopt cooling kettles.
[0019] Optionally, the first evaporation and concentration device is also connected with an acid solution adding device for adjusting the pH of mother liquor I.
[0020] Optionally, a first stirrer is arranged inside the first evaporation and concentration device.
[0021] Optionally, a second stirrer is arranged inside the second evaporation and concentration device.
[0022] Optionally, a sodium bicarbonate adding port is arranged on the reactor.
[0023] Compared with the prior art, the utility model has the following beneficial effects:
[0024] The utility model uses a double decomposition reaction to prepare sodium bicarbonate, which can be calcined to produce sodium carbonate and returned to the previous coking process for use. In addition to a large amount of ammonium chloride, the reaction mother liquor also contains a small amount of residual sodium chloride, sodium bicarbonate and ammonium bicarbonate. The pH of the mother liquor is adjusted to 5-5.5 with hydrochloric acid to convert the sodium bicarbonate and ammonium bicarbonate into sodium chloride and ammonium chloride. Sodium chloride and ammonium chloride can be sold as products to realize the recycling of by-products. In the utility model, the mother liquor is recycled to extract sodium chloride and ammonium chloride, avoiding the waste caused by the low yield due to the dissolution of part of sodium bicarbonate in the solution. The sodium bicarbonate, sodium chloride and ammonium chloride recovered by the utility model have high purity, among which the purity of sodium bicarbonate > 97%, the nitrogen content in ammonium chloride > 24.5%, and the purity of sodium chloride > 95%, achieving remarkable social and economic benefits.
[0025] The utility model recycles and reuses high-salt industrial wastewater as a raw material for preparing sodium bicarbonate, which is an economical and environmentally friendly method for wastewater resource utilization. The utility model uses the mother liquor after producing sodium bicarbonate to extract sodium chloride and ammonium chloride, and the condensed water generated by evaporation can also be used as product washing water. It is a green and pollution-free technical method for wastewater harmless treatment and resource utilization, truly realizing "zero discharge" and circular economy, and no wastewater is generated in the whole process. Description of the Drawings
[0026] Figure 1 is a flow chart of the utility model.
[0027] Figure 2 is a device connection diagram of the utility model. Detailed Embodiments
[0028] In order to make the purpose and technical solution of the utility model clearer, the utility model is further described in detail below. The experimental methods described in the following embodiments are all conventional methods unless otherwise specified: those not indicating specific techniques or conditions in the embodiments are carried out according to the techniques or conditions described in the literature in this field or according to the product specifications; the reagents and materials, unless otherwise specified, can be obtained from commercial channels.
[0029] Embodiment 1
[0030] This embodiment proposes a zero-discharge recycling device for high-salt wastewater mainly composed of sodium chloride, as Figure 2 shown, including: a high-salt wastewater concentration device for concentrating high-salt wastewater;
[0031] The high-salt wastewater concentration device is successively connected to a reactor, a first evaporation concentration device, a first cooling crystallization device, a second evaporation concentration device, and a second cooling crystallization device.
[0032] The reactor, which is a double decomposition reaction kettle, is used to react the concentrated high-salt wastewater with ammonium bicarbonate; the reactor is provided with a first solid-liquid separator, and the first solid-liquid separator is used to perform solid-liquid separation on the reacted high-salt wastewater to obtain mother liquor I and solid sodium bicarbonate;
[0033] The first evaporation concentration device is used to evaporate and concentrate mother liquor I;
[0034] The first cooling crystallization device is used to cool the evaporated and concentrated mother liquor I; the first cooling crystallization device is provided with a second solid-liquid separator, and the second solid-liquid separator is used to perform solid-liquid separation on the cooled mother liquor I to obtain mother liquor II and solid ammonium chloride;
[0035] The second evaporation concentration device is used to evaporate and concentrate mother liquor II; the second evaporation concentration device is provided with a third solid-liquid separator, and the third solid-liquid separator is used to perform solid-liquid separation on the evaporated and concentrated mother liquor II to obtain mother liquor III and solid sodium chloride;
[0036] The second cooling crystallization device is used to cool the evaporated and concentrated mother liquor III; the second cooling crystallization device is provided with a fourth solid-liquid separator, and the fourth solid-liquid separator is used to perform solid-liquid separation on the cooled mother liquor III to obtain mother liquor IV and solid ammonium chloride; mother liquor IV returns to the second evaporation concentration device for evaporation and concentration.
[0037] The first evaporation concentration device and the second evaporation concentration device adopt atmospheric evaporators; the first cooling crystallization device and the second cooling crystallization device adopt cooling kettles. A first stirrer is provided in the first evaporation concentration device, and a second stirrer is provided in the second evaporation concentration device.
[0038] In addition, as Figure 2 shown, the first evaporation concentration device is also connected to an acid solution adding device for adjusting the pH of mother liquor I.
[0039] The method for jointly producing sodium bicarbonate, sodium chloride, and ammonium chloride from sodium chloride high-salt wastewater with zero discharge using the above device, as Figure 1 shown, includes the following steps:
[0040] Step (1): Prepare a nearly saturated sodium chloride solution with a sodium chloride content of 26%. Add ammonium bicarbonate in two batches according to a molar ratio of sodium chloride to ammonium bicarbonate of 1:1 to the solution for a double decomposition reaction. The reaction temperature is 35°C and the reaction time is 1.5 h to precipitate solid sodium bicarbonate. After the wet material is filtered to separate the solid and liquid, wet sodium bicarbonate and mother liquor I are obtained. After the wet sodium bicarbonate is washed with water and dried, sodium bicarbonate products are obtained.
[0041] Step (2): Adjust the pH of mother liquor I obtained in step (1) to 5 - 5.5 by adding HCl. The components of mother liquor I are 21.01% ammonium chloride and 7.89% sodium chloride. Evaporate 38% of the water at a temperature of 80°C to obtain a suspension containing a large amount of ammonium chloride solid. Cool the suspension to 5°C to precipitate ammonium chloride, stir at a rate of 320 rpm for half an hour, and after filtration to separate the solid and liquid, wet ammonium chloride and mother liquor II are obtained. After the wet ammonium chloride is dried, ammonium chloride products are obtained.
[0042] Step (3): Heat mother liquor II to 80°C again for evaporation, evaporate 32% of the water, and precipitate solid sodium chloride. Keep the slurry at 80°C and filter while it is hot to separate the solid and liquid to obtain wet sodium chloride and mother liquor III. Cool mother liquor III to 5°C again to precipitate ammonium chloride, stir at a rate of 320 rpm for half an hour, and after filtration to separate the solid and liquid, wet ammonium chloride and mother liquor IV are obtained. After the wet ammonium chloride is dried, ammonium chloride products are obtained.
[0043] Step (4): Mother liquor IV is returned to step (2) for recycling to extract sodium chloride and ammonium chloride.
[0044] Test Example
[0045] A method for realizing zero discharge of co-producing sodium bicarbonate, sodium chloride and ammonium chloride from high-salt sodium chloride wastewater, using the device of Example 1, includes the following steps:
[0046] Step (1): Take the pretreated coking high-salt sodium chloride wastewater from the factory, and concentrate it nearly 10 times under reduced pressure at a temperature of 90°C to obtain a nearly saturated concentrated solution of sodium chloride with a sodium chloride content of 21%. Add ammonium bicarbonate in two batches according to a molar ratio of sodium chloride to ammonium bicarbonate of 1:1 to the concentrated solution for a double decomposition reaction. The reaction temperature is 35°C and the reaction time is 1.5 h to precipitate solid sodium bicarbonate. After the wet material is filtered to separate the solid and liquid, wet sodium bicarbonate and mother liquor I are obtained. After the wet sodium bicarbonate is washed with water and dried, sodium bicarbonate products are obtained.
[0047] Step (2): Add HCl to the mother liquor I obtained in step (1) to adjust the pH to 5 - 5.5, and send it to the first-stage evaporator for evaporation. Evaporate 32% of the water at a high temperature of 80°C. Send the solution to the cold crystallization tank, cool it down to 10°C to precipitate ammonium chloride, stir at a rate of 300 rpm for half an hour to form an ammonium chloride slurry. After the slurry is filtered to separate the solid and liquid, wet ammonium chloride and mother liquor II are obtained. The wet ammonium chloride is dried to obtain ammonium chloride products.
[0048] Step (3): Mother liquor II enters the second-stage evaporator and is heated to 80°C for evaporation. Evaporate 30% of the water to precipitate sodium chloride. Keep the sodium chloride slurry at 80°C and filter it while it is hot to separate the solid and liquid, obtaining wet sodium chloride and mother liquor III. Mother liquor III is sent to the cold crystallization tank again, cooled down to 10°C to precipitate ammonium chloride, stir at a rate of 300 rpm for half an hour to form an ammonium chloride slurry. After the slurry is filtered to separate the solid and liquid, wet ammonium chloride and mother liquor IV are obtained. The wet ammonium chloride is dried to obtain ammonium chloride products.
[0049] Step (4): Mother liquor IV is returned to step (2) for recycling to extract sodium chloride and ammonium chloride.
[0050] The yield of the sodium bicarbonate product obtained from the reaction is about 58%, the purity of the sodium bicarbonate product is 98%, and it can be calcined to form sodium carbonate for use in the previous coking process. The recovery rate of the by-product ammonium chloride is 67%, the nitrogen content is 24.5%, the recovery rate of sodium chloride is 28%, and the purity is 95%.
[0051] The yield of the sodium bicarbonate product obtained from the reaction is about 60%, the purity of the sodium bicarbonate product is 97%, the recovery rate of the by-product ammonium chloride is 83%, the nitrogen content is 24.7%, the recovery rate of sodium chloride is 32%, and the purity is 96%.
[0052] Comparative Example 1
[0053] Step (1): Take the pre-treated coking sodium chloride high-salt wastewater from the factory, reduce the pressure and concentrate it nearly 5 times at a temperature of 90°C to obtain a sodium chloride concentrate with a sodium chloride content of 11%. Add ammonium bicarbonate to the concentrate in two batches according to a molar ratio of sodium chloride to ammonium bicarbonate of 1:1, carry out a double decomposition reaction at a reaction temperature of 35°C and a reaction time of 1.5 h to precipitate sodium bicarbonate solid. After the wet material is filtered to separate the solid and liquid, wet sodium bicarbonate and mother liquor I are obtained. After the wet sodium bicarbonate is washed with water and dried, sodium bicarbonate products are obtained.
[0054] The purity of the sodium bicarbonate product obtained from the reaction is 97%, and the yield is only 38%. The low sodium chloride content in the initial concentrate results in a low sodium utilization rate.
[0055] Comparative Example 2
[0056] Step (1): Take the pre-treated coking sodium chloride high-salt wastewater from the factory, and concentrate it under reduced pressure by nearly 10 times at a temperature of 90 °C to obtain a nearly saturated concentrated solution of sodium chloride with a sodium chloride content of 21%. Add ammonium bicarbonate to the concentrated solution in two batches according to a molar ratio of sodium chloride to ammonium bicarbonate of 1:1 for a double decomposition reaction. The reaction temperature is 35 °C and the reaction time is 1.5 h. Sodium bicarbonate solid is precipitated. After the wet material is filtered to separate the solid and liquid, wet sodium bicarbonate and mother liquor I are obtained. After the wet sodium bicarbonate is washed with water and dried, sodium bicarbonate product is obtained.
[0057] Step (2): Without adjusting the pH, directly send the mother liquor I obtained in step (1) to the first-stage evaporator for evaporation, and evaporate 32% of the water at a high temperature of 80 °C. Send the solution to the cold crystallization crystallizer, cool it to 10 °C to precipitate ammonium chloride, stir at a rate of 300 rpm for half an hour to form an ammonium chloride slurry. After the slurry is filtered to separate the solid and liquid, wet ammonium chloride and mother liquor II are obtained. After the wet ammonium chloride is dried, ammonium chloride product is obtained.
[0058] Step (3): Mother liquor II enters the second-stage evaporator and is heated to 80 °C for evaporation, evaporating 30% of the water to precipitate sodium chloride. The sodium chloride slurry is filtered while hot at 80 °C to separate the solid and liquid, and wet sodium chloride and mother liquor III are obtained. Mother liquor III is sent to the cold crystallization crystallizer again, cooled to 10 °C to precipitate ammonium chloride, stirred at a rate of 300 rpm for half an hour to form an ammonium chloride slurry. After the slurry is filtered to separate the solid and liquid, wet ammonium chloride and mother liquor IV are obtained. After the wet ammonium chloride is dried, ammonium chloride product is obtained.
[0059] Step (4): Mother liquor IV is returned to step (2) for recycling to extract sodium chloride and ammonium chloride.
[0060] The yield of the obtained sodium bicarbonate product is about 54%, the purity of the sodium bicarbonate product is 98%, and it can be calcined to produce sodium carbonate for use in the previous coking process. However, the recovery rate of the by-product ammonium chloride is only 6%, the purity is 95%, the recovery rate of sodium chloride is 17%, and the purity is 94.4%. The failure to adjust the pH in step (2) results in a serious reduction in the recovery rate and purity of the by-products.
[0061] In addition, it should be noted that the above is only the preferred embodiment of the present invention and is not limited to the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A zero-discharge recycling device for high-salinity wastewater with sodium chloride as the main component, characterized in that: include: A high-salt wastewater concentration device is used to concentrate high-salt wastewater; A reactor, used for reacting the concentrated high-salinity wastewater with ammonium bicarbonate; The reactor is provided with a first solid-liquid separator, which is used to perform solid-liquid separation on the high-salt wastewater after the reaction to obtain mother liquor I and sodium bicarbonate solid; A first evaporation and concentration device, used for evaporating and concentrating the mother liquor I; The first cold crystallizer is used to cool the mother liquor I after evaporation and concentration; The first cold crystallizer is provided with a second solid-liquid separator, and the second solid-liquid separator is used to perform solid-liquid separation on the cooled mother liquor I to obtain mother liquor II and ammonium chloride solid; A second evaporation and concentration device is used to evaporate and concentrate the mother liquor II; the second evaporation and concentration device is provided with a third solid-liquid separator, and the third solid-liquid separator is used to perform solid-liquid separation on the evaporated and concentrated mother liquor II to obtain mother liquor III and sodium chloride solid; The second cold crystallizer is used to cool the mother liquor III after evaporation and concentration; the second cold crystallizer is provided with a fourth solid-liquid separator, and the fourth solid-liquid separator is used to perform solid-liquid separation on the cooled mother liquor III to obtain mother liquor IV and ammonium chloride solid; the mother liquor IV is returned to the second evaporation and concentration device for evaporation and concentration.
2. The zero-discharge recycling device for high-salinity wastewater with sodium chloride as the main component according to claim 1, characterized in that: The reactor is a double decomposition reactor.
3. The zero-discharge recycling device for high-salinity wastewater with sodium chloride as the main component according to claim 1 is characterized in that: The reactor is a double decomposition reactor.
4. The zero-discharge recycling device for high-salinity wastewater with sodium chloride as the main component according to claim 1 is characterized in that: The first evaporation and concentration device and the second evaporation and concentration device adopt normal pressure evaporators.
5. The zero-discharge recycling device for high-salinity wastewater with sodium chloride as the main component according to claim 1 is characterized in that: The first cold crystallizer and the second cold crystallizer adopt cooling kettles.
6. The zero-discharge recycling device for high-salinity wastewater with sodium chloride as the main component according to claim 1 is characterized in that: The first evaporation and concentration device is also connected to an acid adding device for adjusting the pH of the mother liquor I.
7. The zero-discharge recycling device for high-salinity wastewater with sodium chloride as the main component according to claim 1 is characterized in that: The first evaporation and concentration device is provided with a first stirrer.
8. The zero-discharge recycling device for high-salinity wastewater with sodium chloride as the main component according to claim 1 is characterized in that: The second evaporation and concentration device is provided with a second stirrer.
9. The zero-discharge recycling device for high-salinity wastewater with sodium chloride as the main component according to claim 1, characterized in that: The reactor is provided with a sodium bicarbonate adding port.