Treatment method and treatment system for high-salinity mine water

Abstract

The invention provides a treatment method and a treatment system for high-salinity mine water, and belongs to the technical field of mine water treatment. The treatment method comprises the following steps: S1, filtering and separating the high-salinity mine water through a filtering unit to remove suspended matters, so as to obtain filtered produced water; s2, the filtered produced water is subjected to nanofiltration separation through a nanofiltration unit, and nanofiltration concentrated water rich in divalent salt and nanofiltration produced water rich in monovalent salt are obtained; s3, introducing the nanofiltration concentrated water into a first reactor, and adding an agent to remove magnesium ions in the nanofiltration concentrated water, so as to obtain first produced water containing calcium ions and sulfate ions; the medicament comprises a softening agent; s4, introducing the first produced water into a second reactor, and enabling calcium ions and sulfate ions in the first produced water to react to obtain second produced water and calcium sulfate dihydrate; and returning the second produced water to the filtering unit for continuous treatment. The technological process has the advantages of being easy and convenient to operate, small in occupied area, low in system operation cost and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of mine water treatment, and in particular relates to a treatment method and a treatment system for high-mineralization mine water. Background Art

[0002] High-mineralized mine water refers to the total dissolved solids (TDS) mass concentration ≥ 1000mg / L. If it is directly discharged into the environment without desalination treatment, the salt content in the river or lake water will increase, causing surface soil erosion, groundwater level rise, land salinization, vegetation withering, crop yield reduction, etc. With the increasingly severe environmental pressure, the country's environmental protection policies are gradually tightening. Environmental protection departments in many places have restricted the TDS discharged by mine water, and some areas require mine water to achieve zero discharge. Therefore, the development of zero-discharge treatment technology for high-mineralized mine water is imminent. At present, most of the zero-discharge processes for high-mineralized mine water require the removal of hardness in the mine water, which leads to a large dosage of dosing during the treatment process, high dosing costs, and high operating costs of zero-discharge processes. Therefore, it is necessary to carry out technical innovation and development in reducing the operating costs of the process system.

[0003] At present, the commonly used high-mineralization mine water softening processes at home and abroad are mainly sodium hydroxide, soda ash softening process, lime soda ash softening process, the process technology is mature, stable operation, and can remove all hardness in mine water. For example, Chinese patent application CN111635050A discloses a method and device for treating high-mineralization mine water, and its specific process steps are: adding a coagulant to the high-mineralization mine water to carry out a coagulation reaction, and the obtained wastewater is filtered using a solid-liquid separation membrane to remove suspended matter; the filtrate is subjected to a first reverse osmosis concentration treatment to increase the salt concentration; NaOH and Na are added to the first reverse osmosis concentrated water 2 CO 3 , so that the impurity cations are precipitated; then the second solid-liquid separation membrane is used for filtration to remove the solid suspended matter; the obtained filtrate is subjected to the second reverse osmosis concentration treatment; the second reverse osmosis concentrated water is treated by ion exchange to remove the impurity cations; the second reverse osmosis concentrated water is subjected to the third reverse osmosis concentration treatment, and then concentrated and crystallized to obtain the recovered Na 2 SO 4 The patent uses NaOH and Na 2 CO 3 Softening of high-mineralized mine water. Due to the high calcium and magnesium ions in high-mineralized mine water, NaOH and Na 2 CO 3 The usage increases; due to NaOH and Na 2 CO 3The market price is high, resulting in high processing costs for the process, which is difficult to be accepted by existing enterprises. In addition, the system has desalination units such as pretreatment, reverse osmosis and ion exchange, the process flow is complicated, and the mine water is not separated by salt, so the resource utilization rate is low.

[0004] In view of this, it is urgent to develop a low-cost, energy-saving and efficient high-mineralization mine water softening process. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method and system for treating high-mineralized mine water. The present invention couples a nanofiltration unit and a crystallization reaction unit (a first reactor and a second reactor) to separate monovalent salts and divalent salts in high-mineralized mine water, recover high-quality calcium sulfate dihydrate (gypsum) in the wastewater, and has a simple process flow and can realize efficient resource utilization of mine water.

[0006] An object of the present invention is to provide a method for treating high-mineralized mine water, the method comprising the following steps:

[0007] S1. Highly mineralized mine water is filtered and separated through a filtration unit to remove suspended solids and obtain filtered water;

[0008] S2, performing nanofiltration separation on the filtered water through a nanofiltration unit to obtain nanofiltration concentrated water rich in divalent salts and nanofiltration produced water rich in monovalent salts;

[0009] S3, passing the nanofiltration concentrated water into the first reactor, and adding a reagent to remove the magnesium ions therein, to obtain a first produced water containing calcium ions and sulfate ions; the reagent includes a softener;

[0010] S4, passing the first produced water into a second reactor, and reacting the calcium ions and sulfate ions in the first produced water to obtain second produced water and calcium sulfate dihydrate; returning the second produced water to the filtration unit for further treatment.

[0011] In some embodiments, the treatment method further comprises the following steps: S5, calcining the calcium sulfate dihydrate obtained in step S4 in a calcination unit to obtain calcium oxide and sulfur dioxide; in some preferred embodiments, the calcination temperature is 850° C.-1000° C.;

[0012] At least part of the calcium oxide obtained in step S5 is used as the softening agent required in step S3, or at least part of the calcium oxide obtained in step S5 is used to prepare the softening agent required in step S3.

[0013] In some embodiments, step S2 further includes: passing the nanofiltration product water into a concentration unit for concentration treatment to obtain concentrated concentrated water and third product water; and then passing the concentrated concentrated water into a solidification unit for solidification treatment to obtain sodium chloride.

[0014] In some embodiments, in step S1, the recovery rate of the filtered water is ≥90%, and the turbidity is ≤0.20NTU.

[0015] In some embodiments, in step S2, the nanofiltration unit has a retention rate of greater than 95% for sulfate ions and a retention rate of greater than 90% for calcium ions.

[0016] In some embodiments, in step S3, the softening agent is one or both of calcium hydroxide and calcium oxide;

[0017] In some preferred embodiments, the agent further comprises a flocculant. In some more preferred embodiments, the flocculant is PAM, and the flocculant is preferably added at a concentration of 1-3 ppm.

[0018] In some preferred embodiments, in step S3, the softener is added and the pH of the nanofiltration concentrated water is set to 11.2-11.5;

[0019] In some preferred embodiments, in step S3, the softener is added and the molar ratio of calcium ions to sulfate ions in the first produced water is made to be 1:0.8-1:1.2.

[0020] In some embodiments, in step S4, a scale inhibitor deactivator is added to the first produced water, and calcium sulfate seed crystals are added to induce crystallization;

[0021] In some preferred embodiments, the scale inhibitor deactivator is added at a concentration of 3-8 ppm, and the calcium sulfate seed crystal addition amount is 4-10 wt %; in some more preferred embodiments, the scale inhibitor deactivator is ferric chloride and / or polyferric chloride.

[0022] Another object of the present invention is to provide a treatment system for high-mineralization mine water, the treatment system comprising:

[0023] A filtration unit is used to filter and separate high-mineralization mine water to remove suspended matter and obtain filtered water;

[0024] A nanofiltration unit, used for performing nanofiltration separation on the filtered product water to obtain nanofiltration concentrated water rich in divalent salts and nanofiltration product water rich in monovalent salts;

[0025] A first reactor is used to receive the nanofiltration concentrated water and make it contact with a softener to react so as to remove magnesium ions in the nanofiltration concentrated water to obtain a first produced water containing calcium ions and sulfate ions;

[0026] A second reactor; used for receiving the first produced water and reacting the calcium ions and sulfate ions in the first produced water to obtain calcium sulfate dihydrate and second produced water;

[0027] The second reactor is connected to the filtering unit to return the second produced water to the filtering unit for further processing.

[0028] In some embodiments, the treatment system further comprises a calcination unit, which is used to calcine the calcium sulfate dihydrate to obtain sulfur dioxide and calcium oxide for providing the softening agent.

[0029] In some embodiments, the treatment system further comprises a concentration unit and a solidification unit;

[0030] The concentration unit is connected to the nanofiltration unit and is used to receive the nanofiltration product water and perform concentration treatment on it to obtain concentrated concentrated water and third product water;

[0031] The solidification unit is connected to the concentration unit and is used for receiving the concentrated water and solidifying it to obtain sodium chloride.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1) Compared with the existing high-mineralization mine water zero discharge process, the process of the present invention has the advantages of simple operation, small footprint, and low system operating cost;

[0034] 2) In some preferred embodiments, the present invention can recover monovalent salts and divalent salts in wastewater without adding additional softening agents, and the process operation cost and investment cost are low;

[0035] 3) In some preferred embodiments, the present invention induces crystallization of calcium ions and sulfate ions at room temperature, and recovers high-quality gypsum by adjusting the ratio of calcium ions to sulfate ions, thereby saving energy consumption for recovering divalent salts;

[0036] 4) In some preferred embodiments, the present invention calcines the recovered gypsum to generate calcium oxide, a pharmaceutical agent for system softening, and the byproduct sulfur dioxide can be used to make sulfuric acid, thereby improving the resource utilization rate of wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure is a schematic diagram of the structure of a treatment system for high-mineralization mine water in one embodiment of the present invention. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The experimental methods without specific conditions in the examples are usually carried out according to conventional conditions and conditions described in the manual, or according to conditions recommended by the manufacturer. The general equipment, materials, reagents, etc. used are all available from commercial channels unless otherwise specified.

[0040] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features.

[0041] In one aspect, the present invention provides a method for treating high-mineralization mine water, the method comprising the following steps:

[0042] S1. Highly mineralized mine water is filtered and separated through a filtration unit to remove suspended solids and obtain filtered water;

[0043] S2, performing nanofiltration separation on the filtered water through a nanofiltration unit to obtain nanofiltration concentrated water rich in divalent salts and nanofiltration produced water rich in monovalent salts;

[0044] S3, passing the nanofiltration concentrated water into the first reactor, and adding a reagent to remove the magnesium ions therein, to obtain a first produced water containing calcium ions and sulfate ions; the reagent includes a softener;

[0045] S4, passing the first produced water into a second reactor, and reacting the calcium ions and sulfate ions in the first produced water to obtain second produced water and calcium sulfate dihydrate; returning the second produced water to the filtration unit for further treatment.

[0046] In the treatment method of the present invention, firstly, the mine water (mainly containing K + , Ca 2+ , Na + ,Mg 2+ , Cl - , SO 4 2- Then, nanofiltration is used to separate the monovalent salt and the divalent salt to obtain a solution rich in divalent salt (Ca 2+ ,Mg 2+ , SO 4 2-plasma) and nanofiltration concentrates rich in monovalent salts (K + , Na + , Cl - The nanofiltration water produced by the nanofiltration of the concentrated water is used to remove the magnesium ions in the concentrated water to obtain the first produced water; the calcium ions and sulfate ions in the first produced water are reacted in the first reactor to obtain the second produced water and calcium sulfate dihydrate; the second produced water may contain some suspended matter and some unreacted ions, and the second produced water is returned to the upstream filtration unit for further treatment. The treatment method of the present invention is simple to operate, has a short process flow, a small footprint, and a low system operation cost.

[0047] In some embodiments, the treatment method further comprises the steps of:

[0048] S5, calcining the calcium sulfate dihydrate obtained in step S4 in a calcination unit to obtain calcium oxide and sulfur dioxide; preferably, the calcination temperature is 850° C.-1000° C.;

[0049] At least part of the calcium oxide obtained in step S5 is used as the softening agent required in step S3, or at least part of the calcium oxide obtained in step S5 is used to prepare the softening agent required in step S3.

[0050] The present invention calcines the recovered calcium sulfate dihydrate to obtain calcium oxide and sulfur dioxide, wherein part of the calcium oxide is directly reused as a softener or used to make lime milk for reuse as a softener, and the sulfur dioxide is used to make sulfuric acid. In the present invention, there is no need to add additional softening agents, and the monovalent salt and divalent salt in the wastewater can be recovered, and the process operation cost and investment cost are low.

[0051] In some embodiments, step S2 further includes: passing the nanofiltration product water into a concentration unit for concentration treatment to obtain concentrated concentrated water and third product water; and then passing the concentrated concentrated water into a solidification unit for solidification treatment to obtain sodium chloride.

[0052] The third produced water in the present invention can meet the reuse water standard and be returned to the plant for reuse; at the same time, the concentrated water enters the solidification unit, such as the MVR evaporator, to evaporate and obtain high-quality recyclable sodium chloride product salt, and the condensed water can be used as reuse water in the plant.

[0053] In some embodiments, in step S1, the recovery rate of the filtered water is ≥90%, and the turbidity is ≤0.20NTU.

[0054] The present invention removes impurities such as suspended matter in mine water by filtering and separating, so that the obtained filtered water meets the water quality requirements of the subsequent separation system.

[0055] In some embodiments, in step S2, the nanofiltration unit has a retention rate of greater than 95% for sulfate ions and a retention rate of greater than 90% for calcium ions.

[0056] The present invention improves the separation effect of monovalent salt and divalent salt through nanofiltration separation.

[0057] In some embodiments, in step S3, the softening agent is one or more of calcium hydroxide and calcium oxide;

[0058] Preferably, the agent further comprises a flocculant, more preferably, the flocculant is PAM, and its added concentration is preferably 1-3 ppm;

[0059] Preferably, in step S3, the softener is added and the pH of the nanofiltration concentrated water is set to 11.2-11.5;

[0060] Preferably, in step S3, the softener is added so that the molar ratio of calcium ions to sulfate ions in the first produced water is 1:0.8-1:1.2.

[0061] Specifically, after adding the softener, by adjusting the pH value of the nanofiltration concentrated water to 11.2-11.5, most of the magnesium ions are precipitated, and the magnesium ion concentration in the obtained first produced water is ≤24 mg / L. In the present invention, no additional softener is required, and the generated calcium oxide part can be reused as a softener, and can also be used to make lime milk, and the lime milk is further reused as a softener, thereby reducing the cost of adding agents. In addition, by controlling the molar ratio of calcium ions and sulfate ions to be close to 1, the calcium ions and sulfate ions in the first produced water are fully reacted, which is conducive to the crystallization of calcium sulfate to obtain gypsum, and will not cause the enrichment of calcium ions and sulfate ions in the first produced water.

[0062] In some embodiments, in step S4, a scale inhibitor deactivator is added to the first produced water, and calcium sulfate seed crystals are added to induce crystallization;

[0063] Preferably, the scale inhibitor deactivator is added at a concentration of 3-8 ppm, and the calcium sulfate seed crystal addition amount is 4-10 wt %; more preferably, the scale inhibitor deactivator is ferric chloride and / or polyferric chloride.

[0064] In the present invention, a scale inhibitor deactivator is added to make calcium ions and sulfate ions react, and calcium sulfate seed crystals are added to induce crystallization under normal temperature conditions to obtain gypsum.

[0065] On the other hand, see Figure 1 The present invention also provides a treatment system for high-mineralization mine water.

[0066] The processing system comprises:

[0067] A filtration unit is used to filter and separate high-mineralization mine water to remove suspended matter and obtain filtered water;

[0068] A nanofiltration unit, used for performing nanofiltration separation on the filtered product water to obtain nanofiltration concentrated water rich in divalent salts and nanofiltration product water rich in monovalent salts;

[0069] A first reactor is used to receive the nanofiltration concentrated water and make it contact with a softener to react so as to remove magnesium ions in the nanofiltration concentrated water to obtain a first produced water containing calcium ions and sulfate ions;

[0070] A second reactor; used for receiving the first produced water and reacting the calcium ions and sulfate ions in the first produced water to obtain calcium sulfate dihydrate and second produced water;

[0071] The second reactor is connected to the filtering unit to return the second produced water to the filtering unit for further processing.

[0072] Specifically, the filtration unit is provided with a water inlet for receiving high-mineralization mine water, and the water production port of the filtration unit is connected to the water inlet of the nanofiltration unit; the concentrate outlet of the nanofiltration unit is connected to the water inlet of the first reactor; the first reactor is also provided with a feeding port, and the water production port of the first reactor is connected to the water inlet of the second reactor, the second reactor is also provided with a feeding port, and the water production port of the second reactor is connected to the water inlet of the filtration unit.

[0073] After the high-mineralization mine water enters the filtration unit to remove suspended matter and other impurities, the filtered water obtained enters the nanofiltration unit and performs nanofiltration separation on the monovalent salt and divalent salt therein to obtain nanofiltration concentrated water rich in divalent salt and nanofiltration produced water rich in monovalent salt; the nanofiltration concentrated water enters the first reactor, and at the same time, a softener (preferably a flocculant) is added to the first reactor to remove magnesium ions in the concentrated water to obtain the first produced water; the first produced water enters the second reactor, and at the same time, a scale inhibitor deactivator and calcium sulfate seeds are added to the second reactor to induce crystallization at room temperature to obtain the second produced water and calcium sulfate dihydrate; the second produced water continues to enter the filtration unit to remove suspended matter and other impurities, and then undergoes subsequent treatment. The entire device is simple and has low operating costs.

[0074] In some embodiments, the treatment system further comprises a calcination unit, which is used to calcine the calcium sulfate dihydrate to obtain sulfur dioxide and calcium oxide for providing the softening agent.

[0075] Among them, calcium oxide is recycled as a softener, which can further reduce the cost of adding chemicals, and sulfur dioxide is used to make sulfuric acid to obtain products with added value.

[0076] In some embodiments, in order to maximize the resource utilization of monovalent salts in wastewater, the treatment system further includes a concentration unit and a solidification unit;

[0077] The concentration unit is connected to the nanofiltration unit, and is used to receive the nanofiltration produced water and perform concentration treatment on it to obtain concentrated concentrated water and third produced water, wherein the third produced water can meet the reuse water standard and be returned to the plant for reuse;

[0078] The solidification unit is connected to the concentration unit and is used for receiving the concentrated water and solidifying it to obtain sodium chloride. The condensed water can be used as recycled water in the plant.

[0079] Specifically, the water inlet of the concentration unit is communicated with the water outlet of the nanofiltration unit, and the water outlet of the concentration unit is communicated with the water inlet of the solidification unit.

[0080] The method and system for treating high-mineralized mine water provided by the present invention are described in detail below in conjunction with specific embodiments.

[0081] The contents of various ions in high mineralization mine water are shown in Table 1 below:

[0082] Table 1 Contents of various ions in high mineralization mine water

[0083]

[0084] Example 1

[0085] Highly mineralized mine water enters the filtration unit at a flow rate of 10 t / h, and the system operating pressure is set to 0.10 MPa. The suspended matter and other impurities in the mine water are removed by the filtration unit, and the recovery rate of the filtered water is 90%, and the turbidity is 0.10 NTU; the filtered water enters the nanofiltration unit at a flow rate of 16.52 t / h, and the nanofiltration system operating pressure is 0.75 MPa, and the retention rate of sulfate ions is 96%, and the retention rate of calcium ions is 91%, and nanofiltration concentrated water rich in divalent salts and nanofiltration produced water rich in monovalent salts are obtained;

[0086] The nanofiltration concentrated water enters the first reactor at a flow rate of 6.61 t / h. At the same time, calcium hydroxide (softener) and a PAM flocculant with a concentration of 2 ppm are added to the first reactor respectively. The pH value of the nanofiltration concentrated water is adjusted to 11.3 by controlling the amount of calcium hydroxide added, so that most of the magnesium ions are precipitated, and the magnesium ion concentration in the obtained first produced water is 18 mg / L, and the molar ratio of calcium ions to sulfate ions in the first produced water is 1:1.1; the first produced water enters the second reactor at a flow rate of 6.60 t / h, and ferric chloride with a mass concentration of 5 ppm is added to the second reactor to react the calcium ions and sulfate ions in the first produced water, and then calcium sulfate seeds with a mass concentration of 5% are added to the second reactor. Gypsum is generated under the induction of the calcium sulfate seeds, and the gypsum generation amount is 83 kg / h, and the second produced water is obtained at the same time; the second produced water returns to the filtration unit at a flow rate of 6.52 t / h;

[0087] The nanofiltration water enters the concentration unit at a flow rate of 9.91 t / h, and the monovalent salt therein is highly concentrated to 110 g / L, and the tertiary water is obtained at the same time. The tertiary water (salt concentration 0.40 g / L) can be reused as recycled water at a flow rate of 9.11 t / h; the concentrated water enters the solidification unit at a flow rate of 0.80 t / h, and the MVR crystallization solidification system is used to obtain high-quality sodium chloride with a yield of 84.3 kg / h and high-quality condensed water with a flow rate of 0.71 t / h. The condensed water can be used as recycled water in the plant;

[0088] The gypsum obtained from the second reactor enters the roasting unit at a yield of 83kg / h for calcination at a temperature of 1000°C to generate calcium oxide and sulfur dioxide. Part of the calcium oxide is used for softening agent dosing in the first reactor, and the by-product sulfur dioxide can be used to make sulfuric acid.

[0089] The changes in ion composition of high-mineralized mine water during the specific treatment process are shown in Table 2 below:

[0090] Table 2 Results of changes in ion content in high-mineralized mine water during specific treatment

[0091]

[0092] From the results in the table, it can be seen that the high-mineralized mine water is filtered through the nanofiltration system to obtain nanofiltration water, and the calcium and magnesium ion concentrations of the nanofiltration water are reduced to below 1mmol / L, meeting the water quality requirements of the subsequent concentration unit; the calcium and magnesium ions in the mine water are enriched in the nanofiltration concentrated water, exceeding the solubility of calcium sulfate. After the first and second reactors, the calcium, magnesium and sulfate ions in the nanofiltration concentrated water are greatly reduced and resource products are generated for recycling. The raw water is separated by the nanofiltration unit, which effectively reduces the processing volume of the first and second reactors, thereby reducing the investment cost of the system. The first and second reactors are both operated at room temperature, reducing the energy consumption of the system. The resource products generated by the second reactor can be returned to the system for use, reducing the system's reagent addition cost.

[0093] Example 2

[0094] Highly mineralized mine water enters the filtration unit at a flow rate of 10 t / h, and the system operating pressure is set to 0.14 MPa. The suspended matter and other impurities in the mine water are removed by the filtration unit, and the recovery rate of the filtered water is 90%, and the turbidity is 0.16 NTU; the filtered water enters the nanofiltration unit at a flow rate of 16.52 t / h, and the nanofiltration system operating pressure is 0.80 MPa, and the retention rate of sulfate ions is 97%, and the retention rate of calcium ions is 92%, and nanofiltration concentrated water rich in divalent salts and nanofiltration produced water rich in monovalent salts are obtained;

[0095] The nanofiltration concentrated water enters the first reactor at a flow rate of 6.61 t / h. At the same time, calcium hydroxide (softener) and a PAM flocculant with a concentration of 2 ppm are added to the first reactor respectively. The pH value of the nanofiltration concentrated water is adjusted to 11.2 by controlling the amount of calcium hydroxide added, so that most of the magnesium ions are precipitated, and the magnesium ion concentration in the obtained first produced water is 20 mg / L, and the molar ratio of calcium ions to sulfate ions in the first produced water is 1:1; the first produced water enters the second reactor at a flow rate of 6.60 t / h, and polyferric chloride with a mass concentration of 6 ppm is added to the second reactor to react the calcium ions and sulfate ions in the first produced water, and then calcium sulfate seeds with a mass concentration of 5% are added to the second reactor. Gypsum is generated under the induction of the calcium sulfate seeds, and the gypsum generation amount is 83 kg / h, and the second produced water is obtained at the same time; the second produced water returns to the filtration unit at a flow rate of 6.52 t / h;

[0096] The nanofiltration water enters the concentration unit at a flow rate of 9.91t / h, and the monovalent salt therein is highly concentrated to 120g / L, and the tertiary water is obtained at the same time. The tertiary water (salt concentration 0.42g / L) can be reused as recycled water at a flow rate of 9.15t / h; the concentrated water enters the solidification unit at a flow rate of 0.76t / h, and the MVR crystallization solidification system is used to obtain high-quality sodium chloride with a yield of 84.3kg / h and high-quality condensed water with a flow rate of 0.64t / h. The condensed water can be used as recycled water in the plant;

[0097] The gypsum obtained from the second reactor enters the roasting unit at a yield of 83kg / h for calcination at a temperature of 980°C to generate calcium oxide and sulfur dioxide. Part of the calcium oxide is used for softening agent dosing in the first reactor, and the by-product sulfur dioxide can be used to make sulfuric acid.

[0098] The changes in ion composition of high-mineralized mine water during the specific treatment process are shown in Table 3 below:

[0099] Table 3 Results of changes in ion content in high-mineralized mine water during specific treatment

[0100]

[0101] From the results in the table, it can be seen that the high-mineralized mine water is filtered through the nanofiltration system to obtain nanofiltration water, and the calcium and magnesium ion concentrations of the nanofiltration water are reduced to below 1mmol / L, meeting the water quality requirements of the subsequent concentration unit; the calcium and magnesium ions in the mine water are enriched in the nanofiltration concentrated water, exceeding the solubility of calcium sulfate. After the first and second reactors, the calcium, magnesium and sulfate ions in the nanofiltration concentrated water are greatly reduced and resource products are generated for recycling. The raw water is separated by the nanofiltration unit, which effectively reduces the processing volume of the first and second reactors, thereby reducing the investment cost of the system. The first and second reactors are both operated at room temperature, reducing the energy consumption of the system. The resource products generated by the second reactor can be returned to the system for use, reducing the system's reagent addition cost.

[0102] In summary, the present invention first pre-treats the high-mineralization mine water, removes impurities such as suspended matter in the wastewater through a filtration unit, and then uses a nanofiltration unit to separate monovalent salt and divalent salt. The divalent salt-rich nanofiltration concentrated water enters the first reactor to remove magnesium ions in the wastewater, and then enters the second reactor to recover the divalent salt calcium sulfate (gypsum) at room temperature. The gypsum enters the roasting furnace for calcination to generate calcium oxide and sulfur dioxide. The calcium oxide is used to make lime milk or reused as a softener, and the sulfur dioxide is used to make sulfuric acid, thereby realizing the resource utilization of divalent salt in the wastewater; the monovalent salt-rich nanofiltration water is concentrated and solidified to generate high-purity monovalent salt sodium chloride and recycled water; the calcium hydroxide added by the system is generated inside the system, and no additional agent is required to remove hardness, the system has a small amount of drug addition, and the zero-emission treatment cost is low.

[0103] The above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention.

Claims

1. A method for treating high-mineralization mine water, characterized in that: The steps include: S1. Highly mineralized mine water is filtered and separated through a filtration unit to remove suspended solids and obtain filtered water; S2, performing nanofiltration separation on the filtered water through a nanofiltration unit to obtain nanofiltration concentrated water rich in divalent salts and nanofiltration produced water rich in monovalent salts; S3, passing the nanofiltration concentrated water into the first reactor, and adding a reagent to remove the magnesium ions therein, to obtain a first produced water containing calcium ions and sulfate ions; the reagent includes a softener; S4, passing the first produced water into a second reactor, and reacting the calcium ions and sulfate ions in the first produced water to obtain second produced water and calcium sulfate dihydrate; returning the second produced water to the filtration unit for further treatment.

2. The method for treating high-mineralization mine water according to claim 1, characterized in that: The following steps are also included: S5, calcining the calcium sulfate dihydrate obtained in step S4 in a calcination unit to obtain calcium oxide and sulfur dioxide; preferably, the calcination temperature is 850° C.-1000° C.; At least part of the calcium oxide obtained in step S5 is used as the softening agent required in step S3, or at least part of the calcium oxide obtained in step S5 is used to prepare the softening agent required in step S3.

3. The method for treating high-mineralized mine water according to claim 1, characterized in that: Step S2 also includes: passing the nanofiltration product water into a concentration unit for concentration treatment to obtain concentrated concentrated water and third product water; and then passing the concentrated concentrated water into a solidification unit for solidification treatment to obtain sodium chloride.

4. The method for treating high-mineralized mine water according to any one of claims 1 to 3, characterized in that: In step S1, the recovery rate of the filtered water is ≥90%, and the turbidity is ≤0.20NTU.

5. The method for treating high-mineralized mine water according to any one of claims 1 to 3, characterized in that: In step S2, the nanofiltration unit has a retention rate of more than 95% for sulfate ions and more than 90% for calcium ions.

6. The method for treating high-mineralized mine water according to any one of claims 1 to 3, characterized in that: In step S3, the softening agent is one or both of calcium hydroxide and calcium oxide; Preferably, the agent further comprises a flocculant, more preferably, the flocculant is PAM, and preferably the added concentration of the flocculant is 1-3 ppm; Preferably, in step S3, the softener is added and the pH of the nanofiltration concentrated water is set to 11.2-11.5; Preferably, in step S3, the softener is added and the molar ratio of calcium ions to sulfate ions in the first produced water is 1:0.8-1:1.

2.

7. The method for treating high-mineralized mine water according to any one of claims 1 to 3, characterized in that: In step S4, a scale inhibitor deactivator is added to the first produced water, and calcium sulfate seed crystals are added to induce crystallization; Preferably, the scale inhibitor deactivator is added at a concentration of 3-8 ppm, and the calcium sulfate seed crystal addition amount is 4-10 wt %; more preferably, the scale inhibitor deactivator is ferric chloride and / or polyferric chloride.

8. A system for treating high-mineralized mine water capable of implementing the treatment method according to any one of claims 1 to 7, characterized in that: include: A filtration unit is used to filter and separate high-mineralization mine water to remove suspended matter and obtain filtered water; A nanofiltration unit, used for performing nanofiltration separation on the filtered product water to obtain nanofiltration concentrated water rich in divalent salts and nanofiltration product water rich in monovalent salts; A first reactor is used to receive the nanofiltration concentrated water and make it contact with a softener to react so as to remove magnesium ions in the nanofiltration concentrated water to obtain a first produced water containing calcium ions and sulfate ions; A second reactor; used for receiving the first produced water and reacting the calcium ions and sulfate ions in the first produced water to obtain calcium sulfate dihydrate and second produced water; The second reactor is connected to the filtering unit to return the second produced water to the filtering unit for further processing.

9. The system for treating high-mineralized mine water according to claim 8, characterized in that: The invention also comprises a calcining unit, wherein the calcining unit is used for calcining the calcium sulfate dihydrate to obtain sulfur dioxide and calcium oxide for providing the softening agent.

10. The high-mineralization mine water treatment system according to claim 8, characterized in that: It also includes a concentration unit and a solidification unit; The concentration unit is connected to the nanofiltration unit and is used to receive the nanofiltration product water and perform concentration treatment on it to obtain concentrated concentrated water and third product water; The solidification unit is connected to the concentration unit and is used for receiving the concentrated water and solidifying it to obtain sodium chloride.

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