A new process for removing hardness from coal chemical wastewater by in-situ alkali production
By coupling the crystallization process section with the in-situ alkali production process section, the salt in the water is used to generate alkali to remove hardness, which solves the problems of equipment scaling and clogging and unstable water quality in coal chemical wastewater treatment, realizes stable equipment operation and resource utilization, and simplifies the process flow.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN DONGDAOER MEMBRANE TECH CO LTD
- Filing Date
- 2023-08-23
- Publication Date
- 2026-05-12
AI Technical Summary
Existing coal chemical wastewater treatment technologies suffer from problems such as equipment scaling and clogging, unstable water quality, high reagent costs, complex systems, and large footprints, making it difficult to achieve efficient and stable hardness removal.
The in-situ alkali production method couples the crystallization process section with the in-situ alkali production process section. It uses the salt in the water to produce the alkali required by the system. The crystallization process section removes suspended solids and hardness, while the alkali produced in the in-situ alkali production process section is used to remove hardness in the water. Excess salt in the system is recycled and reused, avoiding scaling and clogging of the equipment.
It has enabled long-term stable operation of the equipment, reduced maintenance complexity and cost, simplified the process flow, improved water quality stability and equipment automation, and avoided the addition of external reagents and the generation of waste liquid.
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Figure CN117383727B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment technology, and in particular to a novel process for removing hardness from coal chemical wastewater using an in-situ alkali production method. Background Technology
[0002] Wastewater from the coal chemical industry is a major headache in wastewater treatment due to its complex composition, high suspended solids content, high hardness, and severe scaling. How to achieve the resource utilization of coal chemical wastewater has become a pressing issue. Currently, the following processes are commonly used for hardness removal from coal chemical wastewater:
[0003] The dual-alkali process typically employs high-density tanks, high-efficiency sedimentation tanks, coagulation sedimentation tanks, and granulation for hardening removal. Its key features include the need to add excessive alkali and adjust the pH of the permeate. However, it places high demands on the accuracy of the system's dosing devices and analytical instruments. In actual production, there is a mismatch between the instantaneous dosing rate and the timely adjustment to water quality fluctuations, resulting in large fluctuations in the quality of the permeate, unstable effluent indicators, and a tendency to scale, which in turn affects the stable operation of subsequent equipment.
[0004] Electrochemical methods include electrocoagulation and electrostatic descaling, which can remove hardness. However, single-unit equipment has low processing capacity and low hardness removal efficiency. It requires the addition of alkali and other chemicals, the pH of the produced water needs to be adjusted, the quality of the effluent is unstable, the electrodes are prone to scaling, maintenance is complicated, and the cost of chemicals is high.
[0005] Ion exchange method: has high requirements for suspended solids, COD, water temperature, hardness and heavy metal ions in the influent. Pretreatment is required to prevent resin contamination and poisoning. At the same time, the wastewater needs to be cooled. Otherwise, it will affect the life of the resin or even cause resin damage. An acid and alkali storage system needs to be set up. At the same time, a large amount of high salt waste liquid is generated.
[0006] Membrane method: It can remove hardness, but the inlet water of the membrane device cannot exceed 45°C. It requires a heat exchange system, cooling water and a complete pretreatment system. Therefore, it has many supporting facilities, complex management, high investment in automation, large system footprint and low engineering reliability. Summary of the Invention
[0007] The purpose of this invention is to provide a new process for in-situ alkali production to remove hardness from coal chemical wastewater. This process utilizes the salt in the water to generate the alkali needed by the system, and then uses the produced alkali to remove the hardness in the water. The upstream and downstream systems are coupled and connected, working together to avoid scaling and clogging in the system while improving the stability and continuity of the equipment. Excess salt in the system can also be recycled and reused.
[0008] To achieve the above objectives, the technical solution of this application is: a new process for removing hardness from coal chemical wastewater by in-situ alkali production, comprising: a crystallization process section, an in-situ alkali production process section, and a water quality conditioning process section;
[0009] The raw water undergoes a crystallization process to remove suspended solids, turbidity, and hardness.
[0010] In the in-situ alkali production process, driven by an external electric field, the anode product is an acid solution, which serves as the acid source for the water quality conditioning process; the cathode product is an alkaline solution, which serves as the alkaline source for the crystallization process.
[0011] The water quality conditioning process section mixes the permeate from the crystallization process section with the acid solution from the in-situ alkali production process section to adjust the pH value of the raw water.
[0012] The crystallization process section is coupled to the in-situ alkali production process section. The water produced by the crystallization process section is a prerequisite for the water intake of the in-situ alkali production process section to avoid scaling and clogging of the equipment. The produced water is sent to the in-situ alkali production process section to produce acids and alkalis, and the generated alkali solution is sent back to the crystallization process section to remove hardness from the water.
[0013] Furthermore, the crystallization process section includes a first-stage column reaction process section containing crystal nucleus magnetic powder. Raw water enters the first-stage column reaction process section to remove suspended solids, turbidity, and hardness, and then reacts with NaOH solution and CO2 gas to remove hardness. The process product water is water with hardness removed.
[0014] Furthermore, the permeate from the crystallization process section is used as the raw material for the in-situ alkali production process section to produce acids and alkalis. The acid solution produced in the in-situ alkali production process section is sent to the water quality adjustment process section, and the alkali solution produced in the in-situ alkali production process section is sent back to the crystallization process section.
[0015] Furthermore, the crystallization process section further includes a first-stage columnar particle reaction process section, a second-stage columnar particle reaction process section, and a third-stage columnar particle reaction process section arranged sequentially. Each stage of the columnar particle reaction process section contains crystal nuclei magnetic powder. Raw water enters the first-stage columnar particle reaction process section and is added with Na2SO4 solution to generate CaSO4, which crystallizes on the magnetic powder to form particles. The product water from the first-stage columnar particle reaction process section enters the second-stage columnar particle reaction process section and reacts with NaOH solution to generate Mg(OH)2 crystals on the solid particles. The product water from the second-stage columnar particle reaction process section enters the third-stage columnar particle reaction process section and is added with NaOH solution and CO2 gas to generate CaCO3 crystals on the solid particles.
[0016] Furthermore, it also includes a concentration and separation process section. The concentration and separation process includes, but is not limited to, RO technology, electrodialysis technology, evaporation technology, etc. After the permeate from the crystallization process section passes through this concentration and separation process section, a monovalent salt solution and a divalent mixed salt solution are obtained. The monovalent salt solution is concentrated and used as the raw liquid for the in-situ alkali production process section, and the divalent mixed salt solution is used as the precipitant for the first-stage column particle reaction process section.
[0017] Furthermore, the crystallization process section includes a two-stage columnar particle reaction process section and a three-stage columnar particle reaction process section arranged sequentially. Each stage of the columnar particle reaction process section is filled with crystal nucleus magnetic powder. Raw water enters the two-stage columnar particle reaction process section and NaOH solution is added. The generated Mg(OH)2 crystallizes on the solid particles. The product water from the two-stage columnar particle reaction process section enters the three-stage columnar particle reaction process section. NaOH solution and CO2 gas are added to the three-stage columnar particle reaction process section, and the generated CaCO3 crystallizes on the solid particles.
[0018] Furthermore, the permeate from the three-stage column particle reaction process enters the water quality conditioning process, where hydrochloric acid solution is added. The permeate then enters the RO concentration process, and the concentrated salt solution serves as the raw material for the in-situ alkali production process, with the desalination solution being recycled.
[0019] Furthermore, part of the product water from the three-stage column particle reaction process enters the in-situ alkali production process, and the other part enters the water quality conditioning process. The water quality conditioning process adds hydrochloric acid solution, adjusts the pH value, and then recycles the product.
[0020] As a further step, the crystallization process section includes a multi-stage columnar crystallization microreactor.
[0021] As a further step, the salt concentration process is achieved through porous electrode ion membrane enrichment technology.
[0022] Furthermore, the in-situ alkali production process is achieved through porous electrode ion-exchange membrane alkali production technology.
[0023] Compared with existing high-density pool and electrochemical processes, this invention is innovative in that it is a coupled process, not a simple equipment integration. The sequence of its processes is advanced and interconnected. By coupling the crystallization process and the in-situ alkali production process in sequence, it achieves one-step hardness removal without adding ions to the water. This effectively solves the problem of scaling and clogging of equipment, enables long-term stable operation of the equipment, and utilizes the salt in the water to generate the alkali required by the system. The alkali produced by the system is used to remove the hardness in the water, and the excess salt in the system can be recycled and reused.
[0024] The crystallization process effectively removes hardness from the water, ensuring that the raw solution in the in-situ alkali production process is free of hardness. This meets the optimal influent conditions for the alkali production process, preventing scaling and clogging. Simultaneously, the alkali produced in the in-situ alkali production process acts as a precipitant in the crystallization process, further removing hardness. Both processes interact and work together to remove hardness. Its advantages are as follows:
[0025] 1. Solve the problem of precipitant source in the column-type crystallization microreactor of the crystallization process section. The precipitant comes from CO2 produced in industrial production and NaOH generated by the generator in the in-situ alkali production process section.
[0026] 2. Solve the problems of raw liquid source and scaling and clogging in the generator of the in-situ alkali production process. The raw liquid comes from the salt in the raw water and is the liquid after hardening is removed by the column-type crystallization microreactor.
[0027] 3. The column-type crystallization microreactor utilizes the alkalinity of the raw water to remove calcium and magnesium ions, forming solid particles. At the same time, it uses the adsorption and filtration effect of crystal nuclei to reduce the turbidity of the water, thus eliminating the need for pretreatment equipment. It has the advantages of being less prone to clogging, low cost, simple maintenance, short process flow, and small footprint. The process is simple and the operation is stable, replacing traditional high-density tanks, reaction tanks, filter presses and other equipment.
[0028] 4. The in-situ alkali production process utilizes the enriched salt to produce acid and alkali under the action of microbubble porous electrodes, which can then be used in other process sections. No external reagents are required, the electrodes are not prone to scaling, resulting in stable operation, high degree of automation, and convenient inspection and maintenance.
[0029] 5. No analytical device is required. The salts in the solution generate acids and bases. The generated bases can remove the hardness of the original water, and the generated acids act as pH adjusters to ensure water neutrality. No waste liquid is generated.
[0030] 6. The solid residue discharge system does not require complex processes such as filter presses, making the system simple and ensuring stable water quality. Attached Figure Description
[0031] Figure 1 This is a flow chart of the process used in Example 1 to treat low-hardness, calcium-containing, magnesium-free wastewater.
[0032] Figure 2 This is a flow chart of Example 2 showing the treatment of high-hardness, high-magnesium, and high-sulfate saline wastewater using this process;
[0033] Figure 3 This is a flow chart of the process used in Example 3 to treat low-hardness, low-salt magnesium-containing wastewater.
[0034] Figure 4 The flowchart for Example 4 shows the process of treating high-hardness, high-magnesium, and high-salt wastewater using this technology. Detailed Implementation
[0035] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the equipment and reagents used in the present invention are commercially available products conventional in this technical field.
[0036] This invention discloses a novel in-situ alkali production process for hardening removal in coal chemical wastewater. The process flow is "precipitant crystallization for hardening removal + in-situ alkali production + pH adjustment." The main core technologies include: 1) utilizing salts in the water to produce acids and alkalis; 2) using the produced alkalis to remove hardness from the water; 3) extraction technologies for calcium sulfate, magnesium hydroxide, and calcium carbonate; and 4) separation and purification technologies for sodium chloride and sodium sulfate. The core process equipment includes a column-type crystallization microreactor, an in-situ alkali generator, and a salt concentration device. This coupled process of column-type crystallization microreactor and in-situ alkali production is applied to the field of coal chemical wastewater treatment. Compared to the high-density tank process in the dual-alkali method, it eliminates the need for a filter press; compared to the electrochemical method, it avoids clogging and scaling; compared to the ion exchange method, it eliminates the need for acid and alkali storage equipment, acid and alkali analysis devices, and the generation of analysis waste liquid; and compared to membrane methods, it eliminates the need for complex pretreatment and offers stable operation.
[0037] Example 1
[0038] A coal chemical production enterprise's raw water is low-hardness wastewater containing calcium but no magnesium. For example, its hardness is 550 mg / L, its salt content is 1200 mg / L, its COD is 690 mg / L, its ammonia nitrogen is 350 mg / L, and its suspended solids content is 62 mg / L. The wastewater is treated using a mixed-salt in-situ alkali production process, including:
[0039] The S1.1 stage column-particle reaction process section can be filled with 60-80 mesh magnetic powder. Raw water passes through a single-stage column-particle crystallization microreactor to remove suspended solids, turbidity, and hardness, reducing the suspended solids level to 7.5 mg / L. Simultaneously, 1% NaOH is added (approximately one-third of the raw water volume), and CO2 gas is introduced. Once the pH is controlled at 9-10, the CO2 gas introduction is stopped. This yields an alkaline solution with a hardness of 60-80 mg / L and a pH of 9-10.
[0040] S2. The in-situ alkali production process section is achieved through a microbubble porous electrode generator. Each electrode group consumes approximately 0.1kW of energy and operates at 5V. A portion of the product water from the first-stage column-particle reaction process section serves as the raw solution for the in-situ alkali production process section. Driven by an external electric field, the anode product is a 1% acid solution, which serves as the acid source for the water quality conditioning process section. The cathode product is a 1% NaOH solution, which serves as the alkali source for the first-stage column-particle reaction process section.
[0041] S3. Water quality conditioning process section, which is achieved through porous electrode ion membrane alkali production technology. Another part of the product water from the first-stage column particle reaction process section passes through this water quality conditioning process section, and acid solution produced by the in-situ alkali production process section is added to adjust the pH value of the water and reduce the COD index. The product water is a neutral solution with pH=7-8, COD index is 560mg / L, and turbidity is 7.5mg / L.
[0042] Example 2
[0043] A coal chemical plant's raw water is saline wastewater with high hardness, high magnesium, and high sulfate content. For example, its hardness is 15000 mg / L, salt content is 3500 mg / L, magnesium ion content is 900 mg / L, sulfate content is 650 mg / L, COD is 350 mg / L, ammonia nitrogen is 390 mg / L, and suspended solids content is 80 mg / L. A salt separation and in-situ alkali production process is used, where sodium sulfate removes calcium ions from the water, and then alkalinity generated by an in-situ alkali generator removes the remaining hardness. This process combines salt separation crystallization for hardness removal with in-situ alkali production, including:
[0044] The S1.1 stage column-particle reaction process section can be filled with 60-80 mesh magnetic powder, which is achieved through a first-stage column-particle crystallization microreactor. When the raw water passes through the first-stage column-particle reaction process section, a 3% Na2SO4 solution is added to generate CaSO4, which crystallizes on the magnetic powder to form particles. The magnetic powder particles can also remove suspended solids and reduce turbidity in the water. The resulting product water with suspended solids of 4.2 mg / L and hardness of approximately 1900 mg / L enters the second-stage column-particle reaction process section.
[0045] The S2.2 stage column particle reaction process section can be loaded with 60-80 mesh magnetic powder, which is achieved through a 2-stage column particle crystallization microreactor; in this process section, an 8%-10% NaOH solution is added, and the generated Mg(OH)2 crystals on the solid particles to obtain product water with a pH of about 11.5-11.8 and a hardness of about 1650 mg / L, which then enters the 3-stage column particle reaction process section;
[0046] The S3.3-stage column-particle reaction process section can be filled with 60-80 mesh magnetic powder, which is achieved through a 3-stage column-particle crystallization microreactor. In this process section, an 8%-10% NaOH solution and CO2 gas are added. When the pH is controlled at 9-10, the CO2 gas is stopped. The generated CaCO3 crystals on the solid particles, resulting in product water with a pH of about 9-10 and a hardness of about 80 mg / L. Part of the product water enters the salt concentration process section, and the other part enters the water quality conditioning process section.
[0047] S4. Salt Separation and Concentration Section: The permeate from the three-stage column-particle reactor process is concentrated to obtain a 4% monovalent NaCl solution and a 3% divalent Na₂SO₄ mixed salt solution. The monovalent NaCl solution is concentrated to 8%-10% and used as the feed liquid for the in-situ alkali production process. The divalent Na₂SO₄ solution is used as the dosing solution for the first-stage column-particle reactor process. This section serves two purposes: firstly, to concentrate the salts, thereby reducing the scale of subsequent in-situ alkali production equipment and improving efficiency; secondly, to separate the divalent and monovalent salts.
[0048] S5. In the in-situ alkali production process section, the monovalent salt solution from the salt concentration process section is used as the raw liquid for in-situ alkali production. Under the drive of an external electric field, the anode product is a 5% acid solution, which is used as the acid solution for the water quality adjustment process section; the cathode product is a 5% NaOH solution, which is used as the alkali solution for the second-stage column particle reaction process section and the third-stage column particle reaction process section.
[0049] S6. Water quality conditioning process section: After the permeate from the 3-stage column-type crystallization microreactor passes through this water quality conditioning process section, an acid solution produced by in-situ alkali production is added to adjust the pH value of the water and reduce the COD index. The permeate is a neutral solution with pH=7-8, COD index of 560mg / L, and turbidity of 7.5mg / L.
[0050] Calcium and magnesium ions in wastewater are extracted by particle encapsulation and adsorption, and the acid and alkali produced by the in-situ alkali production process are cleverly used to supply each process stage; no pretreatment process is required, no external reagents are needed, no waste liquid is generated, and the cost is low.
[0051] Example 3
[0052] A coal chemical plant uses low-hardness, low-salt, magnesium-containing wastewater as its raw water source. For example: salt content: 650 mg / L, TDS: 1500 mg / L, total hardness: 500 mg / L, magnesium content: less than 200 mg / L, COD: 250 mg / L, ammonia nitrogen: 290 mg / L, suspended solids: 75 mg / L. The plant employs an in-situ concentration alkali production process. The concentration equipment is not limited to RO, electrodialysis, or evaporation. First, RO is used to concentrate the salt in the water. Then, the concentrated RO water is sent to the generator in the in-situ alkali production process section, where the generated alkalinity removes the hardness from the water. This includes:
[0053] The S1.2 stage column particle reaction process section can be loaded with 60-80 mesh magnetic powder, which is achieved through a 2-stage column particle crystallization microreactor; in this process section, an 8-10% NaOH solution is added, and the generated Mg(OH)2 crystals on the solid particles, resulting in product water with a pH of about 11.5-11.8 and a hardness of about 350 mg / L, which then enters the 3-stage column particle reaction process section.
[0054] The S2.3 stage column particle reaction process section can be filled with 60-80 mesh magnetic powder, which is achieved through a 3-stage column particle crystallization microreactor. In this process section, 8-10% NaOH solution and CO2 gas are added. When the pH is controlled at 9-10, the CO2 gas is stopped. The generated CaCO3 crystals on the solid particles, resulting in product water with a pH of about 9-10 and a hardness of about 20 mg / L. This product water then enters the water quality conditioning process section.
[0055] S3. Water Conditioning Section: After the permeate from the 3-stage column-type crystallization microreactor passes through this water conditioning section, a 5% hydrochloric acid solution is added to adjust its pH to 7-8, approximately neutral. This neutral solution then proceeds to the RO concentration section.
[0056] The S4.RO concentration process section concentrates the neutral solution, and the concentrated solution, which is an 8%-10% brine solution, is used as the feed liquid for the in-situ alkali production process section, and the desalination liquid is recycled.
[0057] S5. The raw liquid in the in-situ alkali production process is a concentrated solution. Under the drive of an external electric field, the anode product is a 5% acid solution, which is used as the acid solution in the water quality conditioning process; the cathode product is a 5% NaOH solution, which is used as the alkali solution in the second-stage column particle reaction process and the third-stage column particle reaction process.
[0058] Example 4
[0059] A coal chemical plant's raw water is high-hardness, high-magnesium, and high-salt wastewater, for example: TDS: 12000 mg / L, hardness: 2200 mg / L, magnesium ion: 700 mg / L; COD: 220 mg / L, ammonia nitrogen: 270 mg / L, suspended solids: 72 mg / L. The plant uses the salt in the water to produce alkali to remove magnesium ions, and then uses the remaining alkalinity to remove calcium ions. The product water is then blended with the de-hardened water, and after meeting the standards, it is sent out. This includes:
[0060] The S1.2 stage column particle reaction process section can be loaded with 60-80 mesh magnetic powder, which is achieved through a 2-stage column particle crystallization microreactor; a 1% NaOH solution is added to this process section, and the generated Mg(OH)2 crystals on the solid particles to obtain product water with a pH of about 11.5-11.8 and a hardness of about 1550 mg / L, which then enters the 3-stage column particle reaction process section;
[0061] The S2.3-stage column-particle reaction process section can be filled with 60-80 mesh magnetic powder, which is achieved through a 3-stage column-particle crystallization microreactor. In this process section, a 1% NaOH solution and CO2 gas are added. When the pH is controlled at 9-10, the CO2 gas is stopped. The generated CaCO3 crystals on the solid particles, resulting in product water with a pH of about 9-10 and a hardness of about 25 mg / L. Part of the product water enters the in-situ alkali production process section, and the other part enters the water quality conditioning process section.
[0062] S3. The raw liquid in the in-situ alkali production process section is the output liquid of the three-stage column particle reaction process section. Under the drive of an external electric field, the anode product is a 1% acid solution, which is used as the acid solution in the water quality adjustment process section; the cathode product is a 1% NaOH solution, which is used as the alkali solution in the two-stage column particle reaction process section and the three-stage column particle reaction process section.
[0063] S4. Water quality conditioning process section: After the permeate from the 3-stage column-type crystallization microreactor passes through this water quality conditioning process section, a 1% hydrochloric acid solution is added to adjust the pH value of the solution to 7-8, approximately neutral. The neutral solution is then recycled.
[0064] The chemical reactions involved in the above embodiments include:
[0065] SO4 2- +Ca 2+ =CaSO4↓ (1)
[0066] Mg 2+ +2OH - +=Mg(OH)2↓ (2)
[0067] HCO3 - +OH - +Ca 2+ =CaCO3↓+H2O (3)
[0068] NaCl + H₂O = NaOH (anion) + HCl (cation) (4)
[0069] This invention presents an innovative coupled process of "precipitant crystallization for hardness removal + in-situ alkali production + pH adjustment," which effectively solves the problem of equipment scaling and clogging, achieving one-step hardness removal. Its innovation lies in: utilizing alkali in the water to remove hardness, and utilizing salt in the water to generate the alkali required by the system; excess salt in the system can also be recycled. The in-situ alkali production process has certain requirements for hardness; low-hardness feed solution helps the continuous and stable operation of the alkali production process and avoids scaling. The alkali produced by the in-situ alkali generator is used to remove hardness from the columnar crystallization microreactor. The coupling of these two processes utilizes the hardness removal function of the columnar crystallization microreactor to meet the optimal influent conditions for in-situ alkali production, while also utilizing the alkali produced by the in-situ alkali generator for hardness removal. They are mutually dependent and complementary, achieving optimal process coupling and maximizing the performance of each.
[0070] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made to the invention. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.
Claims
1. A novel process for in-situ alkali production to remove hardness from coal chemical wastewater, characterized in that, include: Crystallization process section, in-situ alkali production process section, water quality conditioning process section; The raw water undergoes a crystallization process to remove suspended solids, turbidity, and hardness. In the in-situ alkali production process, driven by an external electric field, the anode product is an acid solution, which serves as the acid source for the water quality conditioning process. The cathode product is an alkaline solution, which serves as the source of alkali solution for the crystallization process. The water quality conditioning process section mixes the permeate from the crystallization process section with the acid solution from the in-situ alkali production process section to adjust the pH value of the raw water. The crystallization process section is coupled to the in-situ alkali production process section. The water produced by the crystallization process section is a prerequisite for the water intake of the in-situ alkali production process section. The produced water is sent to the in-situ alkali production process section to produce acid and alkali, and the generated alkali solution is sent back to the crystallization process section to remove hardness from the water. The crystallization process section includes a first-stage columnar particle reaction section, a second-stage columnar particle reaction section, and a third-stage columnar particle reaction section arranged sequentially. Each stage of the columnar particle reaction section contains 60-80 mesh magnetic powder for crystal nuclei. Raw water enters the first-stage columnar particle reaction section and is added with Na2SO4 solution to generate CaSO4, which crystallizes on the magnetic powder to form particles. The permeate from the first-stage columnar particle reaction section enters the second-stage columnar particle reaction section and reacts with NaOH solution to generate Mg(OH)2 crystals on the solid particles. The permeate from the second-stage columnar particle reaction section enters the third-stage columnar particle reaction section and is added with NaOH solution and CO2 gas to generate CaCO3 crystals on the solid particles. The third-stage columnar particle reaction section... Part of the produced water enters the salt concentration process section, and the other part enters the water quality conditioning process section. The permeate from the three-stage column-particle reaction process is concentrated to obtain a monovalent salt solution and a divalent salt solution. The monovalent salt solution is used as the raw material for the in-situ alkali production process, and the divalent salt solution is used as the dosing solution for the first-stage column-particle reaction process.
2. The novel process for in-situ alkali production to remove hardness from coal chemical wastewater according to claim 1, characterized in that, The salt concentration process section includes RO technology, electrodialysis technology, and evaporation technology. After the permeate from the crystallization process section passes through this salt concentration process section, a monovalent salt solution and a divalent mixed salt solution are obtained. The monovalent salt solution is concentrated and used as the raw liquid for the in-situ alkali production process section, and the divalent mixed salt solution is used as the precipitant for the first-stage column particle reaction process section.
3. The novel process for in-situ alkali production to remove hardness from coal chemical wastewater according to claim 1, characterized in that, The crystallization process section includes a multi-stage columnar crystallization microreactor.
4. A novel process for in-situ alkali production to remove hardness from coal chemical wastewater according to claim 1, characterized in that, The salt concentration process is achieved through porous electrode ion membrane enrichment technology.
5. A novel process for in-situ alkali production to remove hardness from coal chemical wastewater according to claim 1, characterized in that, The in-situ alkali production process is achieved through porous electrode ion membrane alkali production technology.