Treatment method of high-calcium-hardness mine water

Abstract

The invention relates to the technical field of mine water treatment, and discloses a treatment method of high-calcium-hardness mine water. The method comprises the following steps: (1) adjusting water chemical components of the mine water, so that the pH value of the mine water is 8-10, the mass ratio of sodium ions to calcium ions is 1: (4-8), the TDS is 7500-8000 mg / L, and the concentration of bicarbonate ions meets the following conditions: the required concentration of the carbonate ions is calculated according to the solubility product of calcium carbonate; the concentration of the bicarbonate ions is 90% twice the calculated concentration of the bicarbonate ions; and (2) adding gypsum into the mine water obtained in the step (1) to carry out first induced crystallization so as to remove calcium ions in the mine water. The method provided by the invention is used for treating the high-calcium-hardness mine water, can adapt to different inflow water qualities, and further improves the removal rate of calcium ions. The method provided by the invention can effectively ensure that the Ca < 2 + > content of the effluent quality of the mine water reaches the standard, can also reduce the secondary environmental pollution problem, and is low in energy consumption.

Description

Technical Field

[0001] The invention relates to the technical field of mine water treatment, and in particular to a method for treating mine water with high calcium hardness. Background Art

[0002] Hardness is an important indicator of mine water quality, mainly composed of Ca 2+ and Mg 2+ Caused by: Excessive Ca 2+ It will cause the hardness of mine water to exceed the standard, which will not only increase the impact on the human body and the surrounding environment, but also cause harm to equipment and increase operating costs. 2+ The content of Ca in mine water after ultrafiltration and concentration is very low (generally less than 100 mg / L), but due to process requirements, the Ca content in mine water after ultrafiltration and concentration treatment is 2+ The content of Ca in the mine water will increase sharply (about 1000 mg / L), which seriously affects the subsequent process operation. 2+ How to remove it quickly and efficiently becomes the focus.

[0003] The induced crystallization technology is to add suitable carrier particles as external inducing substances to the crystallization reaction system, so that the crystallization products produced by the crystallization reaction are generated on the surface of the particles, and the crystallization reaction system changes from homogeneous nucleation to heterogeneous nucleation, thereby accelerating the process of calcium carbonate crystallization reaction. This method has the advantages of small footprint, short treatment cycle, less precipitated sludge, low water content, and is conducive to subsequent treatment or recovery. It is widely used in treating Ca in mine water. 2+ However, due to the variable water quality of mine water and the defects of the technology itself, the efficiency of gypsum-induced calcium carbonate crystallization to remove high Ca hardness in mine water has been maintained at 60-70%, resulting in high Ca content in the effluent. 2+ Cannot meet the requirements.

[0004] Therefore, how to improve the removal efficiency of high calcium hardness mine water and ensure stable operation is the key to ensure the quality of effluent water. 2+ The key to reaching the content standard. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems existing in the prior art and provide a method for treating high calcium hardness mine water.

[0006] The present invention relates to removing calcium hardness from mine water, and in particular to inducing calcium carbonate crystallization to remove high concentration of Ca in mine water. 2+ A scenario where we discuss how to solve the problem of low efficiency.

[0007] In order to achieve the above object, the present invention provides a method for treating high calcium hardness mine water, wherein the method comprises the following steps:

[0008] (1) adjusting the water chemical composition of the mine water so that the pH value of the mine water is 8-10, the mass ratio of sodium ion to calcium ion is 1:4-8, the TDS is 7500-8000 mg / L, and the concentration of bicarbonate ion satisfies: the required carbonate ion concentration is calculated according to the solubility product of calcium carbonate, so that the concentration of bicarbonate ion is 90% of twice the calculated carbonate ion concentration;

[0009] (2) Adding gypsum to the mine water obtained in step (1) to carry out a first induced crystallization to remove calcium ions in the mine water.

[0010] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0011] (1) The method provided by the present invention is used to treat high calcium hardness mine water, which can adapt to different water qualities and further improve the removal rate of calcium ions;

[0012] (2) The method of the present invention can effectively ensure the quality of mine water Ca 2+ It can not only meet the content standards, but also reduce secondary environmental pollution and have low energy consumption. DETAILED DESCRIPTION

[0013] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0014] A first aspect of the present invention provides a method for treating high calcium hardness mine water, wherein the method comprises the following steps:

[0015] (1) adjusting the water chemical composition of the mine water so that the pH value of the mine water is 8-10, the mass ratio of sodium ion to calcium ion is 1:4-8, the TDS is 7500-8000 mg / L, and the concentration of bicarbonate ion satisfies: the required carbonate ion concentration is calculated according to the solubility product of calcium carbonate, so that the concentration of bicarbonate ion is 90% of twice the calculated carbonate ion concentration;

[0016] (2) Adding gypsum to the mine water obtained in step (1) to carry out a first induced crystallization to remove calcium ions in the mine water.

[0017] When the mine water is treated with ultrafiltration and concentration, Ca 2+The content of calcium will increase sharply, becoming high calcium hardness mine water. The existing technology is mostly to remove high calcium hardness by crystallization-induced calcium carbonate precipitation. However, the existing technology has the following disadvantages: (1) Since the water quality of mine water comes from a wide range of sources and the water quality is unstable, Ca 2+ The content fluctuates greatly, thus affecting the removal rate of high calcium hardness; (2) The efficiency of inducing calcium carbonate crystallization to remove high calcium hardness in mine water is generally not higher than 70%, resulting in Ca 2+ The concentration does not meet the effluent requirement of 100-150 mg / L; (3) It is highly energy-consuming, and a large amount of scale inhibitors need to be added in the subsequent process to prevent hardness blockage.

[0018] If the mine water contains a certain amount of carbonate ions, the bicarbonate ion concentration will be calculated by subtracting the original carbonate ions from the carbonate ion concentration calculated based on the solubility product of calcium carbonate.

[0019] The present invention aims to solve the problem of low efficiency of inducing calcium carbonate crystallization to remove high calcium hardness of mine water, and improves the calcium hardness of mine water by adjusting the water chemical composition of mine water and using gypsum as a crystal seed. 2+ Removal rate.

[0020] In some embodiments of the present invention, KOH or HCl is added to the mine water to adjust the pH value. In the present invention, the pH value is controlled at 8-10, which can make the mine water alkaline and help the precipitation of calcium ions and carbonate ions.

[0021] In some embodiments of the present invention, sodium chloride is added to the mine water to adjust the mass ratio of sodium ions to calcium ions. In the present invention, sodium ions in the water exchange with calcium ions adsorbed on the surface of the colloid, allowing calcium ions to enter the water body, facilitating the precipitation of more calcium ions and carbonate ions.

[0022] In some embodiments of the present invention, KCl is used to adjust the TDS (total dissolved solids) of the mine water. In the present invention, TDS guarantees the content of dissolved matter in water.

[0023] In some embodiments of the present invention, potassium bicarbonate is added to the mine water to adjust the mass ratio of bicarbonate ions to calcium ions. In the present invention, within the pH range of 8-10, bicarbonate can be continuously hydrolyzed into carbonate, and calcium ions and carbonate precipitation can be stably achieved.

[0024] In some embodiments of the present invention, the pH value of the mine water in step (1) is 8.

[0025] In some embodiments of the present invention, the mass ratio of sodium ions to calcium ions is 1:4.

[0026] In some embodiments of the invention, the TDS is 8000 mg / L.

[0027] In some embodiments of the present invention, the dosage of gypsum in step (2) is 0.5-0.6 g / L, preferably 0.5 g / L. The function of gypsum is to provide precipitation seeds to induce the precipitation of calcium ions and carbonate ions.

[0028] In some embodiments of the present invention, the average particle size of the gypsum is less than 0.075 mm.

[0029] In some embodiments of the present invention, the first induced crystallization is performed under stirring conditions.

[0030] In some embodiments of the present invention, the stirring conditions include: 200-300 rpm, preferably 300 rpm; time is 3-5 min, preferably 3 min.

[0031] In some embodiments of the present invention, the stirring is then allowed to stand for 5-10 minutes, preferably 10 minutes.

[0032] In some embodiments of the present invention, the method further comprises:

[0033] (3) adding calcium fluoride particles to the mine water after the first induced crystallization is completed to carry out a second induced crystallization to further remove calcium ions in the mine water.

[0034] In the present invention, calcium fluoride particles can further achieve the scenario where calcium removal efficiency is insufficient after gypsum induction. The dissolution product of calcium fluoride is significantly lower than that of gypsum and calcium carbonate, which is conducive to deep calcium removal.

[0035] In some embodiments of the present invention, the dosage of calcium fluoride particles in step (3) is 0.2-0.8 g / L, preferably 0.2 g / L.

[0036] In some embodiments of the present invention, the average particle size of the calcium fluoride particles is less than 0.075 mm.

[0037] In some embodiments of the present invention, the second induced crystallization is performed under stirring conditions.

[0038] In some embodiments of the present invention, the stirring procedure is as follows: first stirring at a rotation speed of 200-300 rpm for 3-5 min, and then stirring at a rotation speed of 80-100 rpm for 5-10 min.

[0039] In some embodiments of the present invention, the stirring procedure is as follows: first stirring at a rotation speed of 300 rpm for 3 min, and then stirring at a rotation speed of 100 rpm for 5 min.

[0040] In some embodiments of the present invention, the stirring is then allowed to stand for 5-10 minutes, preferably 10 minutes.

[0041] According to a particularly preferred embodiment of the present invention, a method for treating high calcium hardness mine water comprises the following steps:

[0042] (1) First, determine the Ca in mine water 2+ 、CO3 2- and HCO3 - Content;

[0043] (2) Add KOH or HCl to adjust the pH of mine water to 8-9;

[0044] (3) Add NaCl to the mine water to ensure that Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 7500-8000mg / L;

[0045] (4) Add KHCO3 to the mine water to ensure HCO3 - Concentration satisfies: the required carbonate ion concentration is calculated based on the solubility product of calcium carbonate, so that the bicarbonate ion concentration is 90% of twice the calculated carbonate ion concentration;

[0046] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water at a standard amount of 0.5 g / L, continue stirring at a speed of 300 rpm for 3-5 minutes, and then let it stand for 10 minutes;

[0047] (6) CaF2 particles with an average particle size of less than 0.075 mm were added to the mine water at a standard of 0.2 g / L, and the mixture was stirred at a speed of 300 rpm for 3-5 minutes, and then stirred at a speed of 100 rpm for 5 minutes, and then allowed to stand for 10 minutes.

[0048] The present invention will be described in detail below through examples.

[0049] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be obtained through commercial channels.

[0050] Example 1

[0051] This example is used to illustrate the treatment method of high calcium hardness mine water.

[0052] (1) First, determine the Ca in mine water 2+ Content is 900mg / L, CO3 2- The content is 0mg / L and HCO3 - The content is 930mg / L;

[0053] (2) Add KOH or HCl to adjust the pH of the mine water to 8;

[0054] (3) Add NaCl to the mine water to ensure that Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 8000mg / L;

[0055] (4) Add KHCO3 to the mine water to ensure HCO3 - Concentration satisfies: the required carbonate ion concentration is calculated based on the solubility product of calcium carbonate, so that the bicarbonate ion concentration is 90% of twice the calculated carbonate ion concentration;

[0056] (5) According to the standard of 0.5 g / L, gypsum with an average particle size of less than 0.075 mm was added to the mine water, stirred at a speed of 300 rpm for 3 min, and then allowed to stand for 10 min to measure Ca 2+ The concentration of Ca is 125.7 mg / L. 2+ The removal rate is 86.1%.

[0057] Example 2

[0058] This example is used to illustrate the treatment method of high calcium hardness mine water.

[0059] (1) First, determine the Ca in mine water 2+ Content is 900mg / L, CO3 2- The content is 0mg / L and HCO3 - The content is 930mg / L;

[0060] (2) Add KOH or HCl to adjust the pH of the mine water to 8;

[0061] (3) Add NaCl to the mine water to ensure that Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 8000mg / L;

[0062] (4) Add KHCO3 to the mine water to ensure HCO3 - Concentration satisfies: the required carbonate ion concentration is calculated based on the solubility product of calcium carbonate, so that the bicarbonate ion concentration is 90% of twice the calculated carbonate ion concentration;

[0063] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water at a standard of 0.5 g / L, continue stirring at a speed of 300 rpm for 5 min, and then let it stand for 10 min;

[0064] (6) CaF2 particles with an average particle size of less than 0.075 mm were added to the mine water at a standard of 0.2 g / L, and stirred at a speed of 300 rpm for 3 min, then stirred at a speed of 100 rpm for 5 min, and then allowed to stand for 10 min to measure the Ca 2+ The concentration of Ca is 75.2 mg / L. 2+ The removal rate is 91.5%.

[0065] Example 3

[0066] This example is used to illustrate the treatment method of high calcium hardness mine water.

[0067] (1) First, determine the Ca in mine water 2+ Content is 900mg / L, CO3 2- The content is 0mg / L and HCO3 - The content is 930mg / L;

[0068] (2) Add KOH or HCl to adjust the pH of the mine water to 10;

[0069] (3) Add NaCl to the mine water to ensure that Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 8000mg / L;

[0070] (4) Add KHCO3 to the mine water to ensure HCO3 - Concentration satisfies: the required carbonate ion concentration is calculated based on the solubility product of calcium carbonate, so that the bicarbonate ion concentration is 90% of twice the calculated carbonate ion concentration;

[0071] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water at a standard of 0.5 g / L, continue stirring at a speed of 300 rpm for 3 minutes, and then let it stand for 10 minutes;

[0072] (6) CaF2 particles with an average particle size of less than 0.075 mm were added to the mine water at a standard of 0.2 g / L, and stirred at a speed of 300 rpm for 3 min, then stirred at a speed of 100 rpm for 5 min, and then allowed to stand for 10 min to measure the Ca 2+ The concentration of Ca is 132.2 mg / L. 2+ The removal rate is 85.4%.

[0073] Example 4

[0074] This example is used to illustrate the treatment method of high calcium hardness mine water.

[0075] (1) First, determine the Ca in mine water2+ Content is 900mg / L, CO3 2- The content is 0mg / L and HCO3 - The content is 930mg / L;

[0076] (2) Add KOH or HCl to adjust the pH of the mine water to 8;

[0077] (3) Add NaCl to the mine water to ensure that Na + :Ca 2+ The mass ratio is 1:8, and the TDS is 7500mg / L;

[0078] (4) Add KHCO3 to the mine water to ensure HCO3 - Concentration satisfies: the required carbonate ion concentration is calculated based on the solubility product of calcium carbonate, so that the bicarbonate ion concentration is 90% of twice the calculated carbonate ion concentration;

[0079] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water at a standard of 0.5 g / L, continue stirring at a speed of 300 rpm for 3 minutes, and then let it stand for 10 minutes;

[0080] (6) CaF2 particles with an average particle size of less than 0.075 mm were added to the mine water at a standard of 0.2 g / L, and stirred at a speed of 300 rpm for 3 min, then stirred at a speed of 100 rpm for 5 min, and then allowed to stand for 10 min to measure the Ca 2+ The concentration of Ca is 170.4 mg / L. 2+ The removal rate is 81.1%.

[0081] Example 5

[0082] This example is used to illustrate the treatment method of high calcium hardness mine water.

[0083] (1) First, determine the Ca in mine water 2+ Content is 900mg / L, CO3 2- The content is 0mg / L and HCO3 - The content is 930mg / L;

[0084] (2) Add KOH or HCl to adjust the pH of the mine water to 8;

[0085] (3) Add NaCl to the mine water to ensure that Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 8000mg / L;

[0086] (4) Add KHCO3 to the mine water to ensure HCO3- Concentration satisfies: the required carbonate ion concentration is calculated based on the solubility product of calcium carbonate, so that the bicarbonate ion concentration is 90% of twice the calculated carbonate ion concentration;

[0087] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water at a standard of 0.8 g / L, continue stirring at a speed of 300 rpm for 3 minutes, and then let it stand for 10 minutes;

[0088] (6) CaF2 particles with an average particle size of less than 0.075 mm were added to the mine water at a standard of 0.2 g / L, and stirred at a speed of 300 rpm for 3 min, then stirred at a speed of 100 rpm for 5 min, and then allowed to stand for 10 min to measure the Ca 2+ The concentration of Ca is 286.3 mg / L. 2+ The removal rate is 69.2%.

[0089] Example 6

[0090] This example is used to illustrate the treatment method of high calcium hardness mine water.

[0091] (1) First, determine the Ca in mine water 2+ Content is 900mg / L, CO3 2- The content is 0mg / L and HCO3 - The content is 930mg / L;

[0092] (2) Add KOH or HCl to adjust the pH of the mine water to 8;

[0093] (3) Add NaCl to the mine water to ensure that Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 8000mg / L;

[0094] (4) Add KHCO3 to the mine water to ensure HCO3 - Concentration satisfies: the required carbonate ion concentration is calculated based on the solubility product of calcium carbonate, so that the bicarbonate ion concentration is 90% of twice the calculated carbonate ion concentration;

[0095] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water at a standard of 0.5 g / L, continue stirring at a speed of 300 rpm for 3 minutes, and then let it stand for 10 minutes;

[0096] (6) CaF2 particles with an average particle size of less than 0.075 mm were added to the mine water at a standard of 0.5 g / L, and stirred at a speed of 300 rpm for 3 min, then stirred at a speed of 100 rpm for 5 min, and then allowed to stand for 10 min to measure the Ca 2+ The concentration of Ca is 186.6 mg / L. 2+ The removal rate is 79.3%.

[0097] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for treating high calcium hardness mine water, characterized in that: The method comprises the following steps: (1) adjusting the water chemical composition of the mine water so that the pH value of the mine water is 8-10, the mass ratio of sodium ion to calcium ion is 1:4-8, the TDS is 7500-8000 mg / L, and the concentration of bicarbonate ion satisfies: the required carbonate ion concentration is calculated according to the solubility product of calcium carbonate, so that the concentration of bicarbonate ion is 90% of twice the calculated carbonate ion concentration; (2) Adding gypsum to the mine water obtained in step (1) to carry out a first induced crystallization to remove calcium ions in the mine water.

2. The method according to claim 1, wherein: Add KOH or HCl to mine water to adjust pH; Preferably, sodium chloride is added to the mine water to adjust the mass ratio of sodium ions to calcium ions.

3. The method according to claim 1 or 2, wherein: Use KCl to adjust the TDS of mine water; Preferably, potassium bicarbonate is added to the mine water to adjust the concentration of bicarbonate ions.

4. The method according to any one of claims 1 to 3, wherein: The pH value of the mine water in step (1) is 8; Preferably, the mass ratio of sodium ions to calcium ions is 1:

4.

5. The method according to any one of claims 1 to 4, wherein: TDS is 8000mg / L.

6. The method according to any one of claims 1 to 5, wherein: In step (2), the dosage of gypsum is 0.5-0.6 g / L, preferably 0.5 g / L; Preferably, the average particle size of the gypsum is less than 0.075 mm.

7. The method according to any one of claims 1 to 6, wherein: Carrying out the first induced crystallization under stirring conditions; Preferably, the stirring conditions include: 200-300 rpm, preferably 300 rpm; time is 3-5 min, preferably 3 min; Preferably, the mixture is allowed to stand for 5-10 minutes, preferably 10 minutes, after the stirring is completed.

8. The method according to any one of claims 1 to 7, wherein: The method further comprises: (3) adding calcium fluoride particles to the mine water after the first induced crystallization is completed to carry out a second induced crystallization to further remove calcium ions in the mine water.

9. The method according to claim 8, wherein: In step (3), the dosage of calcium fluoride particles is 0.2-0.8 g / L, preferably 0.2 g / L; Preferably, the average particle size of the calcium fluoride particles is less than 0.075 mm.

10. The method according to claim 8 or 9, wherein: Conducting a second induced crystallization under stirring conditions; Preferably, the stirring procedure is as follows: first stirring at a speed of 200-300 rpm for 3-5 min, then stirring at a speed of 80-100 rpm for 5-10 min; Preferably, the stirring procedure is as follows: first stirring at a speed of 300 rpm for 3 min, then stirring at a speed of 100 rpm for 5 min; Preferably, the mixture is allowed to stand for 5-10 minutes, preferably 10 minutes, after the stirring is completed.