CN112225373A

CN112225373A - Mine water treatment method and system

Info

Publication number: CN112225373A
Application number: CN202011015008.7A
Authority: CN
Inventors: 陈晓青; 艾山·玉素莆; 李道清
Original assignee: Shenzhen Delan Ecological Environment Co ltd
Current assignee: Shenzhen Delan Ecological Environment Co ltd
Priority date: 2020-09-24
Filing date: 2020-09-24
Publication date: 2021-01-15

Abstract

The invention provides a mine water treatment method and a system, which comprises the following steps: pretreatment: adding a magnesium agent and calcium oxide into mine water, adjusting the pH, adding PAM, PFS and PAC to remove silicon and hardness, and adjusting the pH again; concentration treatment: concentrating the filtered produced water; salt separation treatment: crystallizing the concentrated water obtained by concentration, and recovering salt. The treatment method disclosed by the invention is low in treatment cost, and can be used for recovering calcium sulfate, sodium chloride and sodium sulfate through evaporative crystallization salt separation treatment, so that the reduction of salt discharge and the maximization of resource recovery are realized.

Description

Mine water treatment method and system

Technical Field

The invention relates to the field of water treatment, in particular to a mine water treatment method and system.

Background

China is the largest coal producing country and consuming country in the world and one of a few countries in the world which take coal as main energy, a large amount of water needs to be poured into a coal mining space in the coal mining process, namely, the mine water is polluted underground water in the coal mining process. The mine water is also a water resource, and the loss of a large amount of mine water not only causes great waste of the water resource, but also pollutes farmlands and surface water systems around mining areas. The mine water is treated and utilized, so that water resource loss can be prevented, water environment pollution is avoided, and the method has important significance for relieving insufficient water supply in a mining area, improving the ecological environment of the mining area and meeting the requirements of production and domestic water to the maximum extent.

At present, a plurality of treatment methods for mine water exist, however, the existing mine water treatment methods have the following problems: the wastewater hardness removal operation cost is high, and the investment cost is high. In addition, the mixed salt obtained after the mine water is treated belongs to hazardous waste and still has harm to the environment.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The first purpose of the invention is to provide a mine water treatment method, which has low treatment cost, can recover calcium sulfate, sodium chloride and sodium sulfate through evaporative crystallization salt separation treatment, realizes reduction of salt discharge and maximization of resource recovery.

The second purpose of the invention is to provide a treatment system of the treatment method, which has the advantages of small scale, low cost and wide applicable water quality range.

In order to achieve the above purpose of the present invention, the following technical solutions are adopted:

the invention provides a mine water treatment method, which comprises the following steps:

pretreatment: adding a magnesium agent and calcium oxide into mine water, adjusting the pH, adding PAM, PFS and PAC to remove silicon and hardness, and adjusting the pH again;

concentration treatment: concentrating the filtered produced water;

salt separation treatment: crystallizing the concentrated water obtained by concentration, and recovering salt.

In the prior art, the method adopted in the hardness removal process is a double-alkali method, and a large amount of sodium carbonate is required to be added. In the hardness removal process, the carbonate and bicarbonate in the hard coating are removed only by adjusting the pH value and adding calcium oxide, sodium carbonate is not needed, and the reduction of the sodium carbonate greatly reduces the cost of hardness removal. In addition, the silicon removing process only uses a magnesium agent, so that the silicon removing cost is reduced. Calcium sulfate, sodium chloride and sodium sulfate can be recovered through subsequent reverse osmosis evaporation crystallization salt separation treatment, so that the low cost reduction of salt discharge and the maximization of resource recovery are realized.

Preferably, the addition amount of the magnesium reagent is 300-350mg/L on the basis of mine water. The magnesium agent is low in price, and the hardness removing cost can be greatly reduced by using the magnesium agent for silicon removal treatment.

Preferably, the addition amount of the calcium oxide is 60-70mg/L on the basis of mine water. Through throwing with calcium oxide, can react with carbonate and bicarbonate radical in the mineral product water, and then get rid of carbonate and bicarbonate radical in the aquatic. Compared with the conventional technology of adding sodium carbonate, the calcium oxide is used for hardness removal, so that the cost of hardness removal is greatly reduced.

Preferably, the dosage of the PAM is 0.1-0.3mg/L on the basis of mine water. PAM can adsorb the suspended particles in water, plays the effect of chain link bridge between the granule, makes the fine particle form bigger wadding group to the speed of sediment has been accelerated, has greatly improved the efficiency of getting rid of the suspended solid.

Preferably, the PAC is added in an amount of 10-30mg/L based on mine water. PAC is the flocculating agent, can condense aquatic suspended solid, is convenient for subsequent filtration treatment.

Preferably, the PFS is added in an amount of 10-20mg/L based on mine water. PFS coagulation speed is fast, and the formation alum floc is thick, and the settlement is fast, and the effluent turbidity is low, can effectively remove suspended matters in water.

Preferably, after the pH is adjusted again, the reverse osmosis evaporation crystallization salt separation treatment is carried out after the filtration is carried out through a filtration process. Furthermore, the filtering process is a valveless filtering pool and ultrafiltration combined filtering process. Through filtration treatment, can effectively get rid of the solid suspended solid in water.

Preferably, a special scale inhibitor for calcium sulfate needs to be added to the produced water after the filtration process in the reverse osmosis process to prevent calcium sulfate scale from depositing and blocking the membrane. Further, the amount of the special scale inhibitor for calcium sulfate is 1-3 mg/L. Because carbonate and bicarbonate radical are basically removed in the hardness removing process and the solubility product constant of calcium sulfate is higher, a small amount of special scale inhibitor for calcium sulfate is added into the reverse osmosis system, and the scale inhibitor also has certain scale inhibition performance on calcium carbonate. Because only the special scale inhibitor for calcium sulfate needs to be added, the descaling cost is effectively reduced.

Preferably, after the reverse osmosis is finished, normal-temperature crystallization treatment is firstly carried out, and then evaporative crystallization salt separation treatment is carried out. Furthermore, in the normal temperature crystallization treatment process, 1-3mg/L of a destroying agent is required to be added for destroying the scale inhibition performance of the special scale inhibitor for calcium sulfate. Through normal temperature crystallization treatment and by using a destructive agent to destroy the scale inhibition performance of the scale inhibitor, calcium sulfate can be precipitated, and then the calcium sulfate is recovered.

The invention also provides a mine water treatment system, which comprises a pretreatment unit, a concentration unit and a salt separation unit which are sequentially connected; the pretreatment unit comprises a silicon removal tank, a valveless filter and a super filter; the concentration unit is a reverse osmosis system.

Preferably, the salt separating unit comprises a normal-temperature crystallization device and an evaporative crystallization salt separating system.

Preferably, the evaporative crystallization salt separation system comprises a sodium chloride evaporative crystallization device, a sodium sulfate freezing crystallization and evaporative dehydration device and a mother liquor drying device.

Compared with the prior art, the treatment method has low treatment cost, and can recover calcium sulfate, sodium chloride and sodium sulfate through evaporative crystallization salt separation treatment, thereby realizing the reduction of salt discharge and the maximization of resource recovery.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a process flow diagram of a mine water treatment method in embodiment 2 of the invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1

Pretreatment: discharging mine water into a silicon removal pool, adding 300mg/L magnesium agent and 60mg/L calcium oxide, adjusting the pH to be about 10, and then sequentially adding 0.1mg/L PAM, 10mg/L PAC and 10mg/L PFS to remove silicon, magnesium, carbonate and bicarbonate in the water; after the silicon and hardness are removed, the pH value of the produced water is adjusted to 6, and then the produced water is filtered by a combined filtering process of a valveless filtering pool and ultrafiltration.

Concentration treatment: and (3) concentrating the filtered produced water in a reverse osmosis system, adding 1mg/L of calcium sulfate special scale inhibitor in the reverse osmosis process, and obtaining reverse osmosis produced water and reverse osmosis concentrated water after the reverse osmosis is finished. And recovering the reverse osmosis produced water.

Salt separation treatment: pouring the reverse osmosis concentrated water into a normal-temperature crystallization system, adding 1mg/L of a destructive agent into the system, and performing normal-temperature crystallization treatment on the reverse osmosis concentrated water; and discharging the produced water after normal temperature crystallization into an evaporative crystallization salt separation system, wherein the system comprises a sodium chloride evaporative crystallization device, a sodium sulfate freezing crystallization and evaporative dehydration device and a mother liquor drying device, and recovering sodium chloride and sodium sulfate after passing through the evaporative crystallization salt separation system.

Example 2

Pretreatment: discharging mine water into a silicon removal pool, adding 325mg/L magnesium agent and 65mg/L calcium oxide, adjusting the pH to be about 11, and then sequentially adding 0.2mg/L PAM, 20mg/L PAC and 15mg/L PFS to remove silicon, magnesium, carbonate and bicarbonate in the water; after the silicon and hardness are removed, the pH value of the produced water is adjusted to 7, and then the produced water is filtered by a combined filtering process of a valveless filtering pool and ultrafiltration.

Concentration treatment: and (3) concentrating the filtered produced water in a reverse osmosis system, adding 2mg/L of a special calcium sulfate scale inhibitor in the reverse osmosis process, and obtaining reverse osmosis produced water and reverse osmosis concentrated water after the reverse osmosis is finished. And recovering the reverse osmosis produced water.

Salt separation treatment: pouring the reverse osmosis concentrated water into a normal-temperature crystallization system, adding 2mg/L of a destructive agent into the system, and performing normal-temperature crystallization treatment on the reverse osmosis concentrated water; discharging the water after normal temperature crystallization into an evaporative crystallization salt separation system, wherein the system comprises a sodium chloride evaporative crystallization device, a sodium sulfate freezing crystallization and evaporative dehydration device and a mother liquor drying device, and recovering sodium chloride and sodium sulfate after passing through the evaporative crystallization salt separation system, and the specific process flow is shown in figure 1.

Example 3

Pretreatment: discharging mine water into a silicon removal pool, adding 350mg/L magnesium agent and 70mg/L calcium oxide, adjusting the pH to be about 12, and then sequentially adding 0.3mg/L PAM, 30mg/L PAC and 20mg/L PFS to remove silicon, magnesium, carbonate and bicarbonate in the water; after the silicon and hardness are removed, the pH value of the produced water is adjusted to 8, and then the produced water is filtered by a combined filtering process of a valveless filtering pool and ultrafiltration.

Concentration treatment: and (3) concentrating the filtered produced water in a reverse osmosis system, adding 3mg/L of a special calcium sulfate scale inhibitor in the reverse osmosis process, and obtaining reverse osmosis produced water and reverse osmosis concentrated water after the reverse osmosis is finished. And recovering the reverse osmosis produced water.

Salt separation treatment: pouring the reverse osmosis concentrated water into a normal-temperature crystallization system, adding 3mg/L of a destructive agent into the system, and performing normal-temperature crystallization treatment on the reverse osmosis concentrated water; and discharging the produced water after normal temperature crystallization into an evaporative crystallization salt separation system, wherein the system comprises a sodium chloride evaporative crystallization device, a sodium sulfate freezing crystallization and evaporative dehydration device and a mother liquor drying device, and recovering sodium chloride and sodium sulfate after passing through the evaporative crystallization salt separation system.

Example 4

The specific procedure was identical to that of example 2, except that the amount of magnesium added was 250 mg/L.

Example 5

The specific procedure was identical to that of example 2, except that the amount of magnesium added was 380 mg/L.

Example 6

The specific procedure was identical to that of example 2, except that the amount of calcium oxide added was 50 mg/L.

Example 7

The specific procedure was identical to that of example 2, except that the amount of calcium oxide added was 80 mg/L.

Example 8

The specific procedure was identical to that of example 2, except that PAM was added in an amount of 0.5 mg/L.

Example 9

The specific procedure was identical to example 2 except that the amount of PAC added was 5 mg/L.

Example 10

The specific procedure was identical to example 2 except that the amount of PAC added was 35 mg/L.

Example 11

The specific procedure was in accordance with example 2, except that the amount of PFS added was 5 mg/L.

Example 12

The specific procedure was in accordance with example 2, except that the amount of PFS added was 25 mg/L.

Comparative example 1

The specific procedure was identical to that of example 2, except that no magnesium reagent was added.

Comparative example 2

The specific procedure was identical to that of example 2, except that no calcium oxide was added.

Comparative example 3

The specific procedure was identical to that of example 2, except that no PAM was added.

Comparative example 4

The specific procedure was identical to example 2 except that no PAC was added.

Comparative example 5

The specific procedure is identical to example 2 except that no PFS is added.

Results of the experiment

Examples 1 to 12 and comparative examples 1 to 5 were tested, and the results are shown in tables 1 and 2.

The mine water used in the embodiment and the comparative examples is a certain mine water in the Xinjiang Tokyo economic technology development area, and the raw water quality is as follows: the concentration of solid suspended matter is 320mg/L, the hardness (calculated by calcium carbonate) is 4112mg/L, the total silicon is 114mg/L, and the total alkalinity is 236mg/L (calculated by calcium carbonate).

TABLE 1

From the above table, it can be seen that the treatment method of mineral water of the present invention effectively reduces the suspended solid concentration, silicon concentration, hardness and total alkalinity. By comparison, the embodiment of example 2 is the best embodiment. In addition, after the treatment by the treatment method, the recovery rate of system water reaches more than 99.1%, the recovery rate of calcium sulfate reaches more than 80%, the purity of sodium chloride reaches more than 96%, and the purity of sodium sulfate reaches more than 99%.

Comparing example 2 in table 1 with comparative example 1, it can be seen that the decrease in the silicon concentration is small without adding the magnesium agent, which indicates that the magnesium agent is indispensable in the present treatment method. Comparing example 2 with examples 4-5, it was found that when the magnesium addition was too large or too small, the silicon concentration was also adversely affected. Therefore, the amount of the magnesium agent added in the embodiment needs to be controlled within a reasonable range to ensure good silicon removal effect.

Comparing example 2 in table 1 with comparative example 2, it can be seen that the hardness of the produced water obtained without addition of calcium oxide is much higher than that obtained with addition of calcium oxide, which indicates that calcium oxide is indispensable in the present treatment method. Comparing example 2 with examples 6-7, it was found that when the calcium oxide is added in an amount too large or too small, the hardness of the produced water is also adversely affected. It can be seen that the amount of calcium oxide added in the examples needs to be controlled within a reasonable range to ensure good hardness removal.

Comparing example 2 in table 1 with comparative examples 3-5, it can be seen that the absence of any of PAC, PAM and PFS results in an excessively high concentration of immobilized suspension, indicating that PAC, PAM and PFS are all indispensable in the present treatment process. Comparing example 2 with examples 8-12, it can be seen that when the PAC, PAM and PFS are added too much or too little, the removal of the solid suspension is not favored. It can be seen that the amounts of PAC, PAM and PFS added in the examples need to be controlled within reasonable ranges to effectively remove the suspended solids.

In a word, the treatment method disclosed by the invention is low in treatment cost, and can be used for recovering calcium sulfate, sodium chloride and sodium sulfate through evaporative crystallization salt separation treatment, so that the reduction of salt discharge and the maximization of resource recovery are realized.

While particular embodiments of the present invention have been illustrated and described, it would be obvious that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

1. A mine water treatment method is characterized by comprising the following steps:

concentration treatment: concentrating the filtered produced water;

2. The mine water treatment method as claimed in claim 1, characterized in that the addition amount of the magnesium reagent is 300-350mg/L based on the mine water.

3. The mine water treatment method according to claim 1, characterized in that the addition amount of the calcium oxide is 60-70mg/L based on mine water.

4. The mine water treatment method according to claim 1, characterized in that the addition amount of PAM is 0.1-0.3mg/L based on mine water.

5. The mine water treatment method according to claim 1, characterized in that the PAC is added in an amount of 10-30mg/L based on mine water.

6. The mine water treatment method according to claim 1, characterized in that the PFS is added in an amount of 10-20mg/L based on mine water.

7. The mine water treatment method according to claim 1, characterized in that after the pH is adjusted again, the salt separation treatment is performed after the reverse osmosis evaporation crystallization after the filtration process.

8. A treatment system according to the method of any one of claims 1 to 7, comprising a pretreatment unit, a concentration unit and a salt separation unit connected in series; the pretreatment unit comprises a silicon removal tank, a valveless filter and a super filter; the concentration unit is a reverse osmosis system.

9. The treatment system of claim 8, wherein the salt separation unit comprises an ambient temperature crystallization device and an evaporative crystallization salt separation system.

10. The processing system as claimed in claim 9, wherein the evaporative crystallization salt separation system comprises a sodium chloride evaporative crystallization device, a sodium sulfate freezing crystallization and evaporative dehydration device and a mother liquor drying device.