Full-resource utilization method for highly-mineralized mine water based on coal-electricity base

Abstract

The invention discloses a full-resource utilization method of highly mineralized mine water based on a coal-electricity base, which comprises the following steps: carrying out ultrafiltration and reverse osmosis treatment on highly mineralized mine water to obtain desalted water and strong brine A; the strong brine A is subjected to tubular microfiltration and bitter brine reverse osmosis treatment, and strong brine B and desalted water are obtained; performing tubular microfiltration and nanofiltration treatment on the strong brine B to obtain salt side brine and nitrate side brine; performing seawater reverse osmosis treatment on the salt side brine to obtain desalted water and strong brine C; the strong brine C enters electrolysis sodium hypochlorite preparation equipment for electrolysis to prepare a sodium hypochlorite sterilizing agent, and the sodium hypochlorite sterilizing agent is added into a circulating cooling water system of the power plant; the saltwater at the nitrate side enters a limestone slurry preparation water sump of a power plant, is mixed with limestone slurry preparation water and then is used for preparing limestone slurry, and then the limestone slurry enters a desulfurization system of the power plant. Based on a coal-electricity base, resource complementation between a coal mine and a power plant is utilized, and all utilization of water resources and salt resources of high-salinity mine water is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a method for fully resource-utilizing highly mineralized mine water based on a coal-fired power base. Background Art

[0002] Coal's fundamental role as the "ballast" and "stabilizer" of energy security will remain unchanged for some time to come. Coal mining inevitably leads to the discharge of mine water. Statistics show that my country's annual mine water discharge exceeds 8 billion tons, the majority of which is highly mineralized (with a total salt content ≥1000 mg / L). This highly mineralized mine water pollutes the surface environment, causing soil compaction and salinization, ultimately leading to a series of problems such as damage to surface ecosystems, impacts on agricultural production, and water resource pollution, as well as waste.

[0003] Currently, the primary treatment process for highly mineralized mine water involves a combination of pretreatment, multi-stage membrane concentration, and salt separation, evaporation, and crystallization. The multi-stage membrane concentration product and evaporation condensate are combined to form product water for reuse, with excess product water meeting discharge standards. Meanwhile, the sodium sulfate and sodium chloride crystals produced during the salt separation and crystallization process are sold, and a small amount of the mother liquor is dried into mixed salts and disposed of as hazardous waste in landfills. However, based on market prices for industrial salt, crystallized sodium sulfate sells for approximately 200-300 yuan per ton, while crystallized sodium chloride is practically given away for free. Overall, the sales value of the product salt is low. Mixed salts are essentially disposed of as hazardous waste in landfills, costing 4,000-6,000 yuan per ton, resulting in high disposal costs. Due to the high initial investment and operating costs associated with these treatment processes, especially the salt separation, evaporation, and crystallization units, operating costs are high, along with high energy consumption. This severely restricts the healthy and stable development of the coal industry and its ability to withstand market risks and shocks.

[0004] The Chinese patent application document with publication number CN111018230A discloses a method for achieving zero discharge and resource utilization of reverse osmosis concentrated water in coal chemical industry. The method first removes hardness and silicon from the reverse osmosis concentrated water, and the effluent is subjected to advanced oxidation to remove organic matter and then enters a nanofiltration system for salt separation to obtain sodium sulfate concentrated water and sodium chloride product water; the sodium sulfate concentrated water is concentrated by a concentrated water membrane, an oxidant is added, and the concentrated water enters a concentrated water thermal concentration treatment, and the effluent enters a potassium sulfate preparation treatment to obtain a potassium sulfate product and a sodium chloride solution; the sodium chloride product water is concentrated by a produced water membrane, and then enters a produced water thermal concentration treatment, and the effluent (30% NaCl) enters an ion membrane electrolysis unit to obtain H2, Cl2 and 30% NaOH solution, the H2 and part of the Cl2 are used to prepare a hydrochloric acid solution, and part of the Cl2 and NaOH solution enters a NaClO preparation unit to prepare NaClO; the reverse osmosis concentrated water is pretreated to prepare nearly saturated sodium chloride and sodium sulfate concentrated brine, without the need for a crystallization process, reducing processing costs, and finally the concentrated brine is prepared into acid and alkali with industrial value and potassium sulfate, achieving resource utilization. The target products of the above application documents are mainly potassium sulfate, 30% NaOH and hydrochloric acid, and NaClO is only a by-product of ion membrane electrolysis of 30% NaCl solution. Its technical process and products are basically consistent with those of the current chlor-alkali industry. It can be understood that a small-scale chlor-alkali industrial production facility has been built within a coal chemical enterprise. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to realize the full resource utilization of high-mineralization mine water.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] A method for fully utilizing highly mineralized mine water in a coal-fired power base comprises the following steps:

[0008] (1) treating the highly mineralized mine water by ultrafiltration and reverse osmosis to obtain desalted water and concentrated brine A;

[0009] (2) subjecting the concentrated brine A obtained in (1) to tubular microfiltration and reverse osmosis treatment of bitter brine to obtain concentrated brine B and desalted water;

[0010] (3) subjecting the concentrated brine B obtained in (2) to tubular microfiltration and nanofiltration to obtain salt-side brine and nitrate-side brine;

[0011] (4) subjecting the salt side brine to seawater reverse osmosis treatment to obtain desalted water and concentrated brine C; the concentrated brine C is fed into the electrolysis equipment for preparing sodium hypochlorite to electrolyze and prepare sodium hypochlorite sterilant, and the sodium hypochlorite sterilant is added to the circulating cooling water system of the power plant;

[0012] (5) The nitrate side brine in (3) enters the limestone slurry preparation water tank of the power plant, is mixed with the limestone slurry preparation water, and is used to prepare the limestone slurry, and then enters the desulfurization system of the power plant.

[0013] Preferably, the method further comprises using the desalted water obtained in (1), (2) and (4) in a circulating cooling water system of a power plant.

[0014] Preferably, in (4), the mass concentration of sodium chloride in the concentrated brine C is ≥9.5%.

[0015] Preferably, in (4), the mass concentration of sodium chloride in the concentrated brine C is 9.5-10.5%.

[0016] Preferably, in (4), the electrolysis equipment for producing sodium hypochlorite automatically dilutes the concentrated brine C to a sodium chloride mass fraction of 3%, and transports the diluted brine to a diaphragmless electrolytic cell for electrolysis.

[0017] Preferably, in (5), the sulfate in the nitrate side brine forms a gypsum slurry, which is dehydrated to obtain gypsum, and the chloride therein enters the desulfurization wastewater and is disposed of using the power plant's own desulfurization wastewater treatment device.

[0018] Preferably, the moisture content of gypsum is no more than 10%.

[0019] Preferably, in (1), the high-mineralization mine water is high-mineralization mine water from which suspended matter and chemical oxygen demand are removed.

[0020] Preferably, in (1), the desalination rate of the reverse osmosis treatment is ≥99% and the recovery rate is ≥80%.

[0021] Preferably, in (2), the desalination rate of the bitter brine reverse osmosis is ≥99%, and the recovery rate is ≥80%.

[0022] Preferably, in (3), the nanofiltration of SO4 2- The desalination rate is ≥99% and the recovery rate is ≥60%.

[0023] Preferably, in (4), the desalination rate of the seawater reverse osmosis is ≥99% and the recovery rate is ≥60%.

[0024] Preferably, in (4), the electrolysis equipment for producing sodium hypochlorite is an electrolysis equipment without an ion membrane.

[0025] Preferably, in (4), the electrolytic sodium hypochlorite production equipment uses a bipolar bipolar electrode, a power supply voltage of 220VAC, and an electrolysis current of 12.5A.

[0026] Aiming at the high-mineralization mine water produced by coal mines and other units, the present invention proposes a "RO+BWRO+NF+SWRO" combined process.

[0027] The present invention uses a TMF+NF salt separation process to separate the concentrated brine produced after two-stage membrane concentration into a salt-side brine (sodium chloride solution) and a nitrate-side brine (a mixed solution of sodium sulfate and sodium chloride). The salt-side brine is further concentrated through a SWRO process and used as a raw material for an electrolytic sodium hypochlorite production device. The generated sodium hypochlorite sterilant is directly used in the power plant's circulating cooling water. The nitrate-side brine enters the power plant's limestone slurry preparation water tank for preparing the power plant's limestone slurry and is solidified and disposed of using the power plant's existing desulfurization system.

[0028] The present invention achieves zero discharge of high-mineralization mine water by fully utilizing resources, and reduces the evaporation and crystallization process compared with traditional mine water zero discharge projects.

[0029] The sodium hypochlorite electrolysis equipment of the present invention adopts the electrolysis of concentrated brine, which innovates the traditional method of using refined sea salt as raw material for the sodium hypochlorite electrolysis equipment. The concentrated brine generated by deep treatment of high-mineralization mine water is directly electrolyzed, thereby reducing the process of solidifying the concentrated brine and the consumption of energy and resources.

[0030] NaClO solution has a short shelf life and needs to be prepared and used immediately in power plants. The electrolytically prepared NaClO solution can be directly used in power plants, solving the problem of NaClO solution being difficult to preserve.

[0031] In summary, the characteristics of the present invention are that it is based on a coal-fired power base, utilizes the resource complementarity between coal mines and power plants, and realizes the full utilization of water resources and salt resources of high-mineralization mine water.

[0032] For a processing capacity of 500m 3 / h of the mine unit, using pretreatment + multi-stage membrane concentration + salt evaporation crystallization combined treatment process, the one-time project estimated investment is about 180 million yuan, direct operating costs (including labor, power, chemicals, consumables, sludge disposal, etc.) is about 15 yuan / m 3 , with annual operating costs of approximately 66 million yuan. The one-time investment in salt evaporation and crystallization is calculated as 25% of the total investment, and operating costs are calculated as 30% of direct operating costs. This reduces the one-time construction investment by 45 million yuan and operating costs by 19.8 million yuan per year. This also saves energy consumption during the evaporation and crystallization process for NaCl solution, Na2SO4 solution, and their mother liquor, as well as the land occupied by the evaporation and crystallization plant, achieving energy conservation and carbon reduction, with significant economic and social and environmental benefits.

[0033] Currently, the cost of a sterilizing agent with 10% effective chlorine content on the market is approximately 800 yuan per ton. Electrolysis of sterilizing agents, however, uses concentrated brine produced from highly mineralized mine water through reverse osmosis and nanofiltration. This utilizes resources and is essentially cost-free, aside from transportation costs. Electrolyzing 1 kg of effective chlorine requires 4.5 kW·h of electricity. Based on the market price of 0.65 yuan / kW·h, the unit cost of producing sodium hypochlorite using concentrated NaCl solution derived from mine water is only 2.9 yuan per kg, approximately 36% of the cost of purchased finished sodium hypochlorite. If the electrolysis is powered by self-generated electricity from a power plant, the unit cost is further reduced.

[0034] Power plants use electrolysis to produce sterilizers, and can adjust the sterilizer addition method from impact addition to continuous addition to avoid problems such as large fluctuations in the effective chlorine concentration of the produced water due to impact addition, insufficiently sustained sterilization effect, and corrosion to equipment caused by high concentrations in a short period of time.

[0035] The method of the present invention can promote the cascade recycling of resources such as high-mineralization mine water in coal mines within coal-fired power bases and power plants, thereby achieving pollution reduction and carbon reduction and green development.

[0036] The present invention aims to solve the problems of existing methods using evaporation and crystallization to treat highly concentrated brine, which have large one-time investment, high energy consumption, high operating cost, low sales value of product salt, great pressure on environmental management of miscellaneous salts, and high miscellaneous salt disposal cost. It proposes a method for treating and resourcefully utilizing highly concentrated brine, which is suitable for deep treatment of highly mineralized mine water and a method for fully resourcefully utilizing associated highly concentrated brine, thereby realizing full resource utilization of highly mineralized mine water.

[0037] The present invention utilizes the technology of electrolyzing 3% NaCl solution in a diaphragm-free electrolytic cell, links regional coal-fired power plants, tap water plants, sewage treatment plants and other units that have demand for sterilizers, constructs an electrolysis and sodium hypochlorite generation facility on-site at the use terminal of the coal-fired power plants and other units, and uses the salt-side brine generated by membrane concentration and membrane separation of high-mineralized mine water as raw material for use by the above-mentioned units, thereby realizing the full resource utilization of regional water and salt resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of the method for full resource utilization of highly mineralized mine water based on a coal-fired power base proposed by the present invention. DETAILED DESCRIPTION

[0039] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0040] The test materials and reagents used in the following examples, and the like, can be obtained from commercial channels unless otherwise specified.

[0041] The specific techniques or conditions not specified in the examples can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0042] Embodiment 1

[0043] The present application proposes a high-mineralization mine water full-resource utilization method based on a coal power base, and a flow chart thereof is shown as follows: Figure 1

[0044] 1. Main components

[0045] 1 ultrafiltration + reverse osmosis (UF+RO), 2 tubular microfiltration + bitter brine reverse osmosis (TMF+BWRO), 3 tubular microfiltration + nanofiltration (TMF+NF), 4 seawater reverse osmosis (SWRO), 5 clean water bin, 6 limestone slurry preparation water bin, 7 power plant desulfurization system, 8 electrolytic sodium hypochlorite unit, 9 power plant circulating cooling water system.

[0046] 2. Use method

[0047] The high-mineralization mine water enters 1 ultrafiltration + reverse osmosis (UF+RO) for desalination, the desalted water enters 5 clean water bin, and the concentrated salt water enters 2 tubular microfiltration + bitter brine reverse osmosis (TMF+BWRO), which first removes F - , Ca 2+ , Mg 2+ , SiO2 and the like through tubular microfiltration (TMF), and then further desalination is carried out through bitter brine reverse osmosis (BWRO), the desalted water enters 5 clean water bin, and the concentrated salt water enters 3 tubular microfiltration + nanofiltration (TMF+NF), which further removes F - , Ca 2+ , Mg 2+ , SiO2 and the like through tubular microfiltration (TMF), and then salt separation treatment is carried out through nanofiltration (NF), respectively forming salt-side salt water (sodium chloride solution) and nitrate-side salt water (sodium sulfate and sodium chloride mixed solution).

[0048] ​The brine on the salt side enters 4 seawater reverse osmosis (SWRO) for reconcentration, and the desalted water enters 5 clear water tank. The concentrated brine is supplied to 8 electrolytic sodium hypochlorite unit by means of tank truck transportation and other means, and is used as the raw material for electrolytic sodium hypochlorite sterilant. The 8 electrolytic sodium hypochlorite unit uses the self-made pure water of the equipment to automatically configure the concentrated brine with a mass concentration of 10% sodium chloride into a sodium chloride solution with a mass concentration of 3%, and then enters the electrolysis unit of the equipment. The electrolysis unit does not need to be equipped with an ion membrane. The stirring effect of the hydrogen generated by electrolysis is used to promote the direct reaction of NaOH and chlorine in the electrolysis unit to generate NaClO with a mass concentration of 1%. The process no longer generates products such as NaOH and chlorine. The product with a mass concentration of 1% NaClO is directly put into the circulating cooling water system of the power plant 9 for use as a sterilant.

[0049] The nitrate side brine (mixed solution of sodium sulfate and sodium chloride) enters the 6 limestone slurry configuration water tank through tank trucks and other means, and is used as water for the desulfurization limestone configuration of the power plant, and finally forms limestone slurry and enters the desulfurization system of the 7 power plant.

[0050] 2.1 Ultrafiltration + Reverse Osmosis (UF+RO)

[0051] After the removal of suspended solids (SS) and chemical oxygen demand (COD), the highly mineralized mine water enters the ultrafiltration + reverse osmosis (UF + RO) process. The UF process first removes contaminants such as fine particles, colloids, and bacteria, while also protecting the RO process. The RO process, with a desalination rate of ≥99% and a recovery rate of ≥80%, desalinates the highly mineralized mine water. The desalted water enters the clear water tank, while the concentrated brine enters the tubular microfiltration + bitter brine reverse osmosis (TMF + BWRO) unit.

[0052] 2.2 Tubular Microfiltration + Bitter Brine Reverse Osmosis (TMF+BWRO)

[0053] The concentrated brine after RO concentration enters the tubular microfiltration + bitter brine reverse osmosis (TMF + BWRO), firstly removes F - , Ca 2+ Mg 2+ , SiO2 and other pollutants, and plays a protective role for reverse osmosis (BWRO); the desalination rate of BWRO is ≥99%, and the recovery rate is ≥80%. The brine is further desalted and concentrated under the action of BWRO, and its desalted water enters the clear water tank, and its brine enters the tubular microfiltration + nanofiltration (TMF+NF) unit.

[0054] 2.3 Tubular Microfiltration + Nanofiltration (TMF+NF)

[0055] The concentrated brine after reverse osmosis concentration of bitter brine enters tubular microfiltration + nanofiltration (TMF + NF), and its ion composition is mainly Na+ 、Cl - 、SO4 2- Tubular microfiltration (TMF) can remove Ca in brine (influent) 2+ Mg 2+ , SiO2, fine particles, colloids, bacteria and other pollutants are further removed, and it plays a protective role in nanofiltration (NF); the desalination rate of NF (for SO4 2- )≥99%, recovery rate≥60% (can be adjusted according to the salt content of the influent), the concentrated brine under the action of NF, the ions in the brine on the salt side are mainly Na + 、Cl - The ions in the nitrate brine are mainly Na + 、SO4 2- 、Cl - The Cl was removed by nanofiltration (NF). - and SO4 2- Separation of SO4 2- further enrichment.

[0056] 2.4 Seawater Reverse Osmosis (SWRO)

[0057] The brine from the salt side of the tubular microfiltration + nanofiltration (TMF+NF) process serves as the feed for seawater reverse osmosis (SWRO). After extensive SWRO treatment, the effluent, desalinated water, enters the clean water tank; the brine is collected in the NaCl concentrate tank. The SWRO desalination rate is ≥99%, and the recovery rate is ≥60%. The recovery rate can be adjusted based on the salinity of the feed water, but a NaCl concentration greater than 9% is recommended to reduce the brine volume, facilitate transport, and facilitate the preparation of dilute brine for electrolytic production of sodium hypochlorite.

[0058] 2.5 Clear water tank

[0059] It is used to store desalted water after RO, BWRO and SWRO deep treatment. Its water quality meets the requirements of the "Industrial Circulating Cooling Water Treatment Design Code" (GB / T 50050) and other standards, and can be directly used for various industrial water.

[0060] 2.6 Limestone slurry water tank

[0061] The water storage tank in the power plant is used to prepare limestone slurry, providing the required water for the preparation of limestone slurry, ensuring that limestone powder can be mixed with water in a certain proportion to produce limestone slurry that meets the requirements.

[0062] 2.7 Power Plant Desulfurization System

[0063] Desulfurization facilities use alkaline solutions such as limestone / lime as desulfurizers to absorb sulfur dioxide and sulfur trioxide in flue gas. Currently, most power plants use purchased limestone powder as the desulfurizer. This powder is delivered to the plant by tanker trucks and unloaded into a limestone powder silo for storage. The limestone powder is then fed into a limestone slurry tank via a screw conveyor, creating a qualified limestone slurry with a solids content of approximately 20% to 30%. This slurry pump then replenishes the absorber as needed.

[0064] Using nitrate-side brine as limestone slurry preparation water is an important resource for repurposing the concentrated sodium sulfate and sodium chloride solutions formed through deep mine water treatment. The nitrate-side brine is pumped into the limestone slurry preparation tank via tank trucks, mixed with the limestone slurry preparation water, and used to prepare the limestone slurry, which then enters the power plant's desulfurization system. The sulfates in the brine ultimately form gypsum slurry, which is pumped out of the slurry pool below the absorption tower and then sent to the gypsum cyclone station for primary dehydration. The gypsum slurry, with a mass concentration of 50%, flows by low gravity into a vacuum belt dehydrator for secondary dehydration, resulting in gypsum with a moisture content of no more than 10%. The chlorides in the gypsum slurry enter the desulfurization wastewater and are disposed of using the power plant's own desulfurization wastewater treatment equipment.

[0065] 2.8 Electrolysis of sodium hypochlorite equipment

[0066] The equipment can automatically dilute the sodium chloride solution to a sodium chloride electrolyte with a mass concentration of about 3%, and then prepare it into a sodium hypochlorite sterilant by electrolyzing the sodium chloride electrolyte. The sodium hypochlorite dosage can be adjusted as needed (according to the "Industrial Circulating Cooling Water Treatment Design Code" (GB / T 50050), the concentration of the continuous addition of the sterilant should be 0.1-0.5 mg / L, corresponding to the circulating water volume of 120,000 t / h of 600MW×2 coal-fired units, the effective chlorine dosage acceleration range is 12kg / h-60kg / h). It is added to the circulating cooling water system of the power plant to achieve the purpose of killing bacteria and microorganisms.

[0067] Using concentrated sodium chloride solution as raw material for electrolytic sodium hypochlorite equipment is an important way to recycle the concentrated sodium chloride solution formed by deep treatment of mine water. Electrolytic sodium hypochlorite equipment consumes about 3200g of NaCl for every 1000g of available chlorine produced. According to the "Design Specifications for Industrial Circulating Cooling Water Treatment", the range of available chlorine added to power plant circulating cooling water is 0.1mg / L to 0.5mg / L. For a single 600MW coal-fired unit, the circulating water volume is about 60,000m 3 / h, it is calculated that the dosage range of effective chlorine is 6kg / h~30kg / h, and the annual consumption of effective chlorine is 52.6t / a~262.8t / a, which corresponds to the consumption of sodium chloride of 168.3t / a~841.0t / a.

[0068] 2.9 Power plant circulating cooling water system

[0069] The circulating cooling water system of a power plant is one of the important auxiliary systems of a power plant. It is mainly used to cool equipment such as generator sets. It is usually composed of a cooling tower, circulating water pumps, condensers, piping systems, and make-up water systems.

[0070] 3. Working Principle

[0071] The present invention is aimed at the zero-discharge process of high-mineralized mine water, and adopts salt separation evaporation crystallization technology to treat the problems of large one-time investment, high energy consumption, high operating cost, low sales value of product salt, high pressure on environmental protection management of miscellaneous salt, and high disposal cost. The invention proposes a technical process based on coal-fired power base, suitable for high-mineralized mine water treatment and full resource utilization.

[0072] After high-mineralization mine water is treated through two-stage reverse osmosis, the desalted water produced is directly supplied to the power plant for use. The tubular microfiltration + nanofiltration (TMF+NF) process is then used to separate the brine into salt-side brine (sodium chloride solution) and nitrate-side brine (a mixed solution of sodium sulfate and sodium chloride). Based on the main components of each brine, appropriate treatment and resource utilization methods are given.

[0073] The resource utilization approach for salt-side brine is electrolysis to produce sodium hypochlorite. The salt-side brine (sodium chloride solution) is re-concentrated through SWRO to further reduce the volume and increase the concentration. When the mass fraction of NaCl in the brine reaches about 10% (the sodium chloride brine is produced in coal mines and utilized in power plants, and the high concentration facilitates storage and transportation; considering the reverse osmosis concentration process combination provided by this method, the sodium chloride concentration after concentration and salt separation is about 10%, for example, 9.5-10.5%), it is used as a raw material for electrolysis of sodium hypochlorite equipment. The equipment can automatically dilute it to a NaCl electrolyte with a concentration of about 3%. The NaCl electrolyte is then electrolyzed to prepare a sodium hypochlorite sterilant, which is added to the circulating cooling water to kill bacteria and microorganisms, thereby realizing the resource utilization of the salt-side brine.

[0074] The resource utilization of nitrate side brine is to transport it into limestone slurry water tank through tank trucks and use it as water for desulfurization limestone in power plants. According to the Technical Supervision Guidelines for Desulfurization Equipment in Thermal Power Plants (DL / T1477), the chloride ions (Cl -) content should be controlled within 10,000 mg / L, and the pH value should be controlled between 5.0 and 6.0. The nitrate-side brine should be used to prepare the limestone slurry without affecting the performance of the limestone slurry before entering the power plant's desulfurization system. The sulfates eventually form gypsum slurry, which is pumped out from the slurry pool at the bottom of the absorption tower and then sent to the gypsum cyclone station for primary dehydration. The gypsum slurry with a mass concentration of 50% flows by low gravity into a vacuum belt dehydrator for secondary dehydration, resulting in gypsum with a moisture content of no more than 10%. Chlorides enter the desulfurization wastewater and are disposed of using the power plant's own desulfurization wastewater treatment equipment.

[0075] The water quality of highly mineralized mine water in a coal mine is shown in Table 1, and the treatment steps are as follows.

[0076] Table 1 Water quality index of high mineralization mine water

[0077]

[0078] Step (1): Highly mineralized mine water first enters an ultrafiltration + reverse osmosis (UF+RO) unit (recovery rate 80%, desalination rate 99%). After ultrafiltration and reverse osmosis filtration and concentration, the quality of the desalted water and brine is shown in Table 2. The desalted water enters the clear water tank and is used by the power plant (as circulating cooling water), while the brine enters step (2).

[0079] Table 2 Water quality indicators after UF+RO treatment

[0080]

[0081] Step (2): The concentrated brine in step (1) enters the tubular microfiltration + bitter brine reverse osmosis (TMF + BWRO) unit (recovery rate 80%, desalination rate 99%), and first removes F by tubular microfiltration (TMF). - , Ca 2+ Mg 2+ , SiO2 and other pollutants, and then enters BWRO for further desalination and concentration. The water quality of desalted water and concentrated brine is shown in Table 3. The desalted water enters the clear water tank and is used by the power plant (used as circulating cooling water in the power plant), and the concentrated brine enters step (3).

[0082] Table 3 Water quality indicators after TMF+BWRO treatment

[0083]

[0084] Step (3): The concentrated brine in step (2) enters the tubular microfiltration + nanofiltration (TMF + NF) unit (recovery rate 60%, sulfate desalination rate 99.9%, chloride desalination rate 1%), and the F is removed by tubular microfiltration (TMF). - , Ca 2+ Mg2+ , SiO2 and other pollutants, and then enter the NF to separate into salt side brine and nitrate side brine, completing the Cl - and SO4 2- The water quality of the salt side brine and the nitrate side brine is shown in Table 4.

[0085] Table 4 Water quality indicators after TMF+NF treatment

[0086]

[0087] Step (4): The salt side brine from step (3) enters a seawater reverse osmosis (SWRO) unit (recovery rate 80%, desalination rate 99%) for further desalination and concentration. The water quality of the desalted water and the concentrated brine is shown in Table 5. The desalted water enters the clean water tank and is used by the power plant (as circulating cooling water), while the concentrated brine enters step (5).

[0088] Table 5 Water quality indicators after SWRO treatment

[0089]

[0090] Step (5): The concentrated brine from step (4) is a sodium chloride solution with a mass concentration of 9.97%. It enters the sodium hypochlorite electrolysis unit. The sodium hypochlorite electrolysis equipment uses pure water produced by the equipment to automatically dilute the 9.97% sodium chloride solution to a sodium chloride electrolyte with a mass concentration of approximately 3%. The solution is then transferred to a diaphragmless electrolytic cell to be prepared into a sodium hypochlorite sterilant. The sterilant is then added to the power plant's circulating cooling water system to kill bacteria and microorganisms. The sodium hypochlorite electrolysis equipment uses bipolar bipolar electrodes, a power supply voltage of 220VAC, and an electrolysis current of 12.5A.

[0091] Step (6): The nitrate side brine from step (3) enters the limestone slurry preparation water tank of the power plant, and is mixed with the limestone slurry preparation water to prepare the limestone slurry. According to the Technical Supervision Guidelines for Desulfurization Equipment in Thermal Power Plants (DL / T1477), the chloride ions (Cl - ) content should be controlled within 10,000 mg / L. Therefore, the amount of water used in the preparation of limestone slurry only needs to be 3 times the volume of the nitrate-side brine or more to meet the standard requirements, that is, the normal amount of water used in the preparation of limestone slurry is 3 times or more than the nitrate-side brine. The prepared limestone slurry enters the desulfurization system of the power plant, and the sulfate therein eventually forms gypsum slurry which is pumped out from the slurry pool at the bottom of the absorption tower and then sent to the gypsum cyclone station for primary dehydration. The gypsum slurry with a mass concentration of 50% flows by gravity at a low flow rate into the vacuum belt dehydrator for secondary dehydration to obtain gypsum with a moisture content of no more than 10%. The chloride therein enters the desulfurization wastewater and is disposed of using the power plant's own desulfurization wastewater treatment equipment.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for fully utilizing highly mineralized mine water in a coal-fired power base, characterized by: The following steps are involved: (1) treating the highly mineralized mine water by ultrafiltration and reverse osmosis to obtain desalted water and concentrated brine A; (2) subjecting the concentrated brine A obtained in (1) to tubular microfiltration and reverse osmosis treatment of bitter brine to obtain concentrated brine B and desalted water; (3) subjecting the concentrated brine B obtained in (2) to tubular microfiltration and nanofiltration to obtain salt-side brine and nitrate-side brine; (4) subjecting the salt side brine to seawater reverse osmosis treatment to obtain desalted water and concentrated brine C; the concentrated brine C is fed into the electrolysis equipment for preparing sodium hypochlorite to electrolyze and prepare sodium hypochlorite sterilant, and the sodium hypochlorite sterilant is added to the circulating cooling water system of the power plant; (5) The nitrate side brine in (3) enters the limestone slurry preparation water tank of the power plant, is mixed with the limestone slurry preparation water, and is used to prepare the limestone slurry, and then enters the desulfurization system of the power plant.

2. The method for fully utilizing highly mineralized mine water based on a coal-fired power base according to claim 1 is characterized by: The method also includes using the desalted water obtained in (1), (2) and (4) in a circulating cooling water system of a power plant.

3. The method for fully utilizing highly mineralized mine water based on a coal-fired power base according to claim 1 is characterized in that: In (4), the mass concentration of sodium chloride in the concentrated brine C is ≥9.5%.

4. The method for fully utilizing highly mineralized mine water based on a coal-fired power base according to claim 1 is characterized in that: In (4), the electrolytic sodium hypochlorite production equipment automatically dilutes the concentrated brine C to a sodium chloride mass fraction of 3%, and transports it to the diaphragmless electrolytic cell for electrolysis.

5. The method for fully utilizing highly mineralized mine water based on a coal-fired power base according to claim 1 is characterized in that: In (5), the sulfate in the nitrate side brine forms gypsum slurry, which is dehydrated to obtain gypsum. The chloride in it enters the desulfurization wastewater and is disposed of using the power plant's own desulfurization wastewater treatment equipment.

6. The method for fully utilizing highly mineralized mine water based on a coal-fired power base according to claim 1 is characterized in that: In (1), the high-mineralization mine water is high-mineralization mine water after the suspended matter and chemical oxygen demand are removed.

7. The method for fully utilizing highly mineralized mine water based on a coal-fired power base according to claim 1 is characterized by: In (1), the desalination rate of the reverse osmosis treatment is ≥99% and the recovery rate is ≥80%.

8. The method for fully utilizing highly mineralized mine water based on a coal-fired power base according to claim 1 is characterized by: In (2), the desalination rate of the bitter brine reverse osmosis is ≥99%, and the recovery rate is ≥80%.

9. The method for fully utilizing highly mineralized mine water based on a coal-fired power base according to claim 1, characterized in that: In (3), the nanofiltration of SO4 2- The desalination rate is ≥99% and the recovery rate is ≥60%.

10. The method for fully utilizing highly mineralized mine water based on a coal-fired power base according to claim 1, characterized in that: In (4), the seawater reverse osmosis has a desalination rate of ≥99% and a recovery rate of ≥60%.

Images