Method for treating high-calcium hardness mine water

Abstract

This invention relates to the field of mine water treatment technology and discloses a method for treating high-calcium-hardness mine water. The method includes the following steps: (1) adjusting the chemical composition of the mine water so that the pH value 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 requirements: the concentration of bicarbonate ions is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions; (2) adding gypsum to the mine water obtained in step (1) to induce crystallization in the first stage to remove calcium ions from the mine water. The method provided by this invention can be used to treat high-calcium-hardness mine water, adapting to different influent water qualities and further improving the calcium ion removal rate. The method of this invention can effectively ensure the quality of the effluent water from the mine water. 2+ It not only meets the content standards but also reduces secondary environmental pollution and has low energy consumption.

Description

Technical Field

[0001] This invention relates to the field of mine water treatment technology, and specifically to a method for treating mine water with high calcium hardness. Background Technology

[0002] Hardness is an important indicator of mine water quality, mainly determined by the calcium content in the water. 2+ and Mg 2+ Caused by excessive Ca. 2+ This can lead to excessive hardness in mine water, not only exacerbating the impact on human health and the surrounding environment, but also damaging equipment and increasing operating costs. Typically, the calcium content in mine water is high. 2+ The content of Ca in mine water is very low (generally below 100 mg / L), but due to process requirements, the concentration of Ca in the mine water after ultrafiltration is high. 2+ The content of [acid / carbohydrate] will increase sharply (to around 1000 mg / L), seriously affecting the subsequent process operation. Therefore, the high concentration of Ca in the mine water after ultrafiltration concentration [is a concern]. 2+ How to remove it quickly and efficiently has become the focus.

[0003] Induced crystallization technology involves adding suitable carrier particles as external inducing substances to the crystallization reaction system. This causes the crystallization products generated during the crystallization reaction to form on the surface of the particles, changing the crystallization reaction system from homogeneous nucleation to heterogeneous nucleation, thereby accelerating the calcium carbonate crystallization process. This method has advantages such as small footprint, short treatment cycle, less sludge production, low water content, and benefits for subsequent treatment or recycling, and is widely used in treating calcium carbonate in mine water. 2+ However, due to the variable quality of the influent water and the inherent limitations of the technology, the efficiency of gypsum-induced calcium carbonate crystallization in removing high Ca hardness from mine water has remained between 60-70%, resulting in low Ca content in the effluent. 2+ The requirements cannot be met.

[0004] Therefore, improving the removal efficiency of high-calcium hardness mine water while maintaining stable operation is crucial to ensuring the quality of the effluent with high calcium content. 2+ The key to achieving the required content. Summary of the Invention

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

[0006] This invention relates to the removal of calcium hardness from mine water, and particularly to the removal of high concentrations of calcium carbonate from mine water by inducing calcium carbonate crystallization. 2+ How to solve the problem of low efficiency in a given scenario.

[0007] To achieve the above objectives, the present invention provides a method for treating high-calcium hardness mine water, wherein the method includes the following steps:

[0008] (1) Adjust the chemical composition 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 requirements: the concentration of carbonate ions required is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions.

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

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

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

[0012] (2) The method of the present invention can effectively ensure the Ca content of the mine water effluent. 2+ It not only meets the content standards but also reduces secondary environmental pollution and has low energy consumption. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] The first aspect of this invention provides a method for treating high-calcium hardness mine water, wherein the method includes the following steps:

[0015] (1) Adjust the chemical composition 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 requirements: the concentration of carbonate ions required is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions.

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

[0017] After the mine water undergoes ultrafiltration concentration treatment, Ca 2+The content of calcium carbonate will increase sharply, resulting in high-calcium hardness mine water. Existing technologies mostly use crystallization-induced calcium carbonate precipitation to remove high-calcium hardness. However, existing technologies have the following drawbacks: (1) Due to the wide range of sources and unstable water quality of mine water, the content of calcium carbonate will increase sharply. 2+ The content fluctuates greatly, thus affecting the removal rate of high Ca hardness; (2) the efficiency of inducing calcium carbonate crystallization to remove high calcium hardness from mine water is generally no higher than 70%, resulting in Ca 2+ (3) The concentration does not meet the effluent requirement of 100-150 mg / L; (4) It is highly energy-intensive, and a large amount of scale inhibitor needs to be added in the subsequent process to prevent hardness blockage.

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

[0019] This invention addresses the problem of low efficiency in removing high calcium hardness from mine water by inducing calcium carbonate crystallization. It achieves this by adjusting the hydrochemical composition of the mine water and using gypsum as a seed crystal, thereby increasing the calcium content in the mine water. 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, controlling the pH value at 8-10 makes the mine water alkaline, which helps calcium ions and carbonate ions to precipitate.

[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 this invention, sodium ions in the water undergo ion exchange with calcium ions adsorbed on the colloidal surface, allowing calcium ions to enter the water body and 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 ensures the content of dissolved substances in the 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 a pH range of 8-10, bicarbonate ions can be continuously hydrolyzed to carbonate ions, thus stably achieving the precipitation of calcium ions and carbonate ions.

[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 present invention, the TDS is 8000 mg / L.

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

[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 carried out under stirring conditions.

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

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

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

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

[0034] In this invention, calcium fluoride particles can further address scenarios where calcium removal efficiency is insufficient after gypsum induction. The solubility of calcium fluoride is significantly lower than that of gypsum and calcium carbonate, which helps to remove calcium more deeply.

[0035] In some embodiments of the present invention, the amount of calcium fluoride particles added 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, a second induced crystallization is carried out under stirring conditions.

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

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

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

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

[0042] (1) First, the Ca in the mine water was measured. 2+ CO3 2- and HCO3 - The content;

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

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

[0045] (4) Add KHCO3 to the mine water to ensure HCO3 - The concentration requirement is: the concentration of carbonate ions required is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions.

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

[0047] (6) Add CaF2 particles with an average particle size of less than 0.075 mm to the mine water at a standard of 0.2 g / L, and continue stirring at a speed of 300 rpm for 3-5 min, then continue stirring at a speed of 100 rpm for 5 min, and let stand for 10 min.

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

[0049] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0050] Example 1

[0051] This embodiment illustrates a method for treating high-calcium-hardness mine water.

[0052] (1) First, the Ca in the mine water was measured. 2+ The content is 900 mg / L, CO3 2- The content is 0 mg / L and HCO3 - The content is 930 mg / 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 Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 8000 mg / L;

[0055] (4) Add KHCO3 to the mine water to ensure HCO3 - The concentration requirement is: the concentration of carbonate ions required is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions.

[0056] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water according to the standard of 0.5 g / L, continue stirring at a speed of 300 rpm for 3 min, let stand for 10 min, and determine the Ca content. 2+ The concentration is 125.7 mg / L. Calculate Ca. 2+ The removal rate was 86.1%.

[0057] Example 2

[0058] This embodiment illustrates a method for treating high-calcium-hardness mine water.

[0059] (1) First, the Ca in the mine water was measured. 2+ The content is 900 mg / L, CO3 2- The content is 0 mg / L and HCO3 - The content is 930 mg / 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 Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 8000 mg / L;

[0062] (4) Add KHCO3 to the mine water to ensure HCO3 - The concentration requirement is: the concentration of carbonate ions required is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions.

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

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

[0065] Example 3

[0066] This embodiment illustrates a method for treating high-calcium-hardness mine water.

[0067] (1) First, the Ca in the mine water was measured. 2+ The content is 900 mg / L, CO3 2- The content is 0 mg / L and HCO3 - The content is 930 mg / 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 Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 8000 mg / L;

[0070] (4) Add KHCO3 to the mine water to ensure HCO3 - The concentration requirement is: the concentration of carbonate ions required is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions.

[0071] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water according to the standard of 0.5 g / L, stir at a speed of 300 rpm for 3 min, and let stand for 10 min.

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

[0073] Example 4

[0074] This embodiment illustrates a method for treating high-calcium-hardness mine water.

[0075] (1) First, the Ca in the mine water was measured.2+ The content is 900 mg / L, CO3 2- The content is 0 mg / L and HCO3 - The content is 930 mg / 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 Na + :Ca 2+ The mass ratio is 1:8, and the TDS is 7500 mg / L;

[0078] (4) Add KHCO3 to the mine water to ensure HCO3 - The concentration requirement is: the concentration of carbonate ions required is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions.

[0079] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water according to the standard of 0.5 g / L, stir at a speed of 300 rpm for 3 min, and let stand for 10 min.

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

[0081] Example 5

[0082] This embodiment illustrates a method for treating high-calcium-hardness mine water.

[0083] (1) First, the Ca in the mine water was measured. 2+ The content is 900 mg / L, CO3 2- The content is 0 mg / L and HCO3 - The content is 930 mg / 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 Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 8000 mg / L;

[0086] (4) Add KHCO3 to the mine water to ensure HCO3- The concentration requirement is: the concentration of carbonate ions required is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions.

[0087] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water according to the standard of 0.8 g / L, stir at a speed of 300 rpm for 3 min, and let stand for 10 min.

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

[0089] Example 6

[0090] This embodiment illustrates a method for treating high-calcium-hardness mine water.

[0091] (1) First, the Ca in the mine water was measured. 2+ The content is 900 mg / L, CO3 2- The content is 0 mg / L and HCO3 - The content is 930 mg / 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 Na + :Ca 2+ The mass ratio is 1:4, and the TDS is 8000 mg / L;

[0094] (4) Add KHCO3 to the mine water to ensure HCO3 - The concentration requirement is: the concentration of carbonate ions required is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions.

[0095] (5) Add gypsum with an average particle size of less than 0.075 mm to the mine water according to the standard of 0.5 g / L, stir at a speed of 300 rpm for 3 min, and let stand for 10 min.

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

[0097] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for treating high-calcium hardness mine water, characterized in that, The method includes the following steps: (1) Adjust the chemical composition 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 requirements: the concentration of carbonate ions required is calculated based on the solubility product of calcium carbonate, and the concentration of bicarbonate ions is 90% of twice the calculated concentration of carbonate ions; (2) Add gypsum to the mine water obtained in step (1) to carry out the first induced crystallization in order to remove calcium ions from the mine water; (3) Add calcium fluoride particles to the mine water after the first induced crystallization is completed to carry out the second induced crystallization in order to further remove calcium ions from the mine water.

2. The method according to claim 1, wherein, KOH or HCl is added to the mine water to adjust the pH value; And / or, 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, wherein, KCl was used to adjust the TDS of mine water; And / or, add potassium bicarbonate to the mine water to adjust the concentration of bicarbonate ions.

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

4.

5. The method according to any one of claims 1-3, wherein, TDS was 8000 mg / L.

6. The method according to any one of claims 1-3, wherein, In step (2), the amount of gypsum added is 0.5-0.6 g / L; And / or, the average particle size of the gypsum is less than 0.075 mm.

7. The method according to any one of claims 1-3, wherein, The first induced crystallization was carried out under stirring conditions.

8. The method according to claim 7, wherein, The stirring conditions include: 200-300 rpm; time is 3-5 min; And / or, let stand for 5-10 minutes after stirring.

9. The method according to claim 8, wherein, The stirring conditions include: 300 rpm; time is 3 min; And / or, let stand for 10 minutes after stirring.

10. The method according to claim 1, wherein, In step (3), the dosage of calcium fluoride granules is 0.2-0.8 g / L; And / or, the average particle size of the calcium fluoride particles is less than 0.075 mm.

11. The method according to claim 1, wherein, Secondary induced crystallization was carried out under stirring conditions.

12. The method according to claim 11, wherein, The stirring procedure is as follows: first stir at a speed of 200-300 rpm for 3-5 minutes, then stir at a speed of 80-100 rpm for 5-10 minutes. And / or, let stand for 5-10 minutes after stirring.

13. The method according to claim 11, wherein, The stirring procedure is as follows: first stir at 300 rpm for 3 minutes, then stir at 100 rpm for 5 minutes. And / or, let stand for 10 minutes after stirring.