Method for treating soluble calcium ions and chloride ions in supernate

Abstract

The invention discloses a method for treating soluble calcium ions and chloride ions in supernate, which comprises the following steps of: selecting sodium sulfate, dissolving the sodium sulfate in deionized water at 0 DEG C, stirring and dispersing into a uniform solution, taking 20ml of supernate by using a 50ml measuring cylinder, pouring the supernate into a 50ml beaker, and uniformly stirring to obtain the soluble calcium ions and chloride ions in the supernate. Adding one of sodium sulfate powder or sodium carbonate powder into the beaker, continuously stirring by using a glass rod to obtain a precipitate, separating by using a vacuum suction flask, taking a total sample, carrying out filter pressing, and measuring the content of calcium ions and sulfate ions in supernate. According to the method for treating the calcium ions and the chloride ions in the supernate for preparing the calcium sulfate or the calcium carbonate, the purpose of preparing calcium sulfate and brine products is achieved by controlling the pH value, measuring the concentration of the calcium ions, adding sodium sulfate powder and the calcium ions to react to generate calcium sulfate precipitates, and reacting sodium ions and the chloride ions to generate a sodium chloride solution.

Description

Technical Field

[0001] The invention relates to the technical field of supernatant ion content determination, and in particular to a method for treating soluble calcium ions and chloride ions in a supernatant. Background Art

[0002] The soda ash industry produces a certain amount of waste residue and waste liquid. The industry basically uses plate bed filter presses to achieve solid-liquid separation, while the supernatant mainly contains calcium ions and chloride ions that are not utilized. The preparation of supernatant of calcium sulfate or calcium carbonate can be achieved through a variety of methods, and the specific method depends on the required form of calcium sulfate and calcium carbonate and the specific requirements of the application. The treatment methods for calcium ions and chloride ions in the supernatant mainly include chemical precipitation, ion exchange, scale inhibition, and nanofiltration membrane.

[0003] Chemical precipitation is a commonly used treatment method. It uses sulfate and sodium carbonate to remove calcium from the mixed solution. By controlling the pH value of the solution and adding an appropriate amount of chemical reagents, calcium ions react with carbonate ions to form calcium carbonate precipitation, thereby achieving the purpose of removing calcium ions. This method can simultaneously remove ammonia nitrogen, and the product can be reused, but different water qualities require different parameters to ensure the treatment effect.

[0004] The ion exchange method has good treatment effect, large treatment capacity, and no secondary pollution to the environment, but the exchange resin needs to be replaced and regenerated, which is expensive and has strict requirements for the expected treatment. This method is suitable for situations with strict requirements on water quality, but the cost is relatively high.

[0005] The scale inhibition technology is simple, but there is little research on it. It may be a more economical treatment method, but further research and development is needed.

[0006] Nanofiltration membrane method has low energy consumption, small land occupation and simple maintenance, but the construction and operation costs are high. This method is suitable for situations with strict requirements on cost and energy consumption, but the investment cost is high.

[0007] In practical applications, the choice of treatment method depends on the specific treatment requirements, cost considerations and the characteristics of the wastewater. No matter which method is used, the removal rate cannot achieve complete removal. Therefore, a treatment method with a higher removal rate is needed. Summary of the invention

[0008] 1. Technical issues to be solved

[0009] In view of the deficiencies of the prior art, the present invention provides a method for utilizing soluble calcium ions and chloride ions in a supernatant.

[0010] (II) Technical solution

[0011] To achieve the above object, the present invention provides the following technical solution: a method for treating soluble calcium ions and chloride ions in a supernatant, comprising the following steps:

[0012] S1: Select sodium sulfate and dissolve it in deionized water at 0°C, stir and disperse it into a uniform solution, divide the uniform solution into three equal parts, and put them in beakers respectively;

[0013] S2: Use a 50ml measuring cylinder to take 20ml of the supernatant, then pour the supernatant into a 50ml beaker, add one of sodium sulfate powder or sodium carbonate powder into the beaker and stir with a glass rod to obtain a precipitate;

[0014] S3: Use a vacuum filtration bottle to separate the calcium sulfate precipitate from the supernatant, and take three samples, namely the total sample, the sample after filtration and the supernatant, to determine the content of calcium ions and sulfate ions therein.

[0015] Preferably, the analytical purity of the sodium sulfate in S1 is ≥99.0%, and the supernatant c(Ca 2+ ) is 37.25g / L.

[0016] Preferably, the supernatant in S2 is poured into a 50 ml beaker and stirred continuously for 5 minutes and then allowed to stand for 10 minutes.

[0017] Preferably, the method for determining the calcium ion content comprises the following steps:

[0018] S1: Weigh 20g of sample, accurate to 0.0002g, place in a 250mL beaker, add water to dissolve, transfer all to a 1000mL volumetric flask, mix well, dilute with water to the scale and shake well. This solution is test solution A, for calcium chloride content;

[0019] S2: Pipette 10mL of test solution A into a 250mL conical flask, adjust the pH to 3-5 with hydrochloric acid solution, add water to about 50mL, add 5mL of triethanolamine solution, 2mL of sodium hydroxide solution, and about 0.1g of calcium reagent carboxylic acid sodium salt indicator, and titrate with disodium ethylenediaminetetraacetic acid standard titration solution. The end point is when the solution changes from red to pure blue;

[0020] S3: Perform a blank test at the same time. Except for not adding test sample, all other reagents added in the blank test are the same as those in the test solution.

[0021] Preferably, the method for determining the sulfate content comprises the following steps:

[0022] S1: Take a certain volume of sample solution, place it in a 400mL beaker, add water to 150mL, add 2 drops of methyl red indicator, add hydrochloric acid solution until the solution turns red, heat to near boiling, quickly add 40mL of hot barium chloride solution, stir vigorously for 2 minutes, and cool to room temperature;

[0023] S2: Add a little barium chloride solution to check whether the precipitation is complete, and filter it with a glass crucible that has been dried and weighed at 120°C in advance. Pour the upper clear liquid into the crucible first, wash the precipitate in the beaker with water several times, and then transfer all the precipitate in the beaker to the crucible;

[0024] S3: Continue washing the precipitate with water several times until the filtrate contains no chloride ions;

[0025] S4: After rinsing the outer wall of the crucible with a small amount of water, dry it in a constant temperature drying oven at 120℃±2℃ for 1h, take it out and weigh it. Then weigh it every 30min of drying until the difference between the two weighings does not exceed 0.0002g. Finally, calculate the sulfate content using the formula.

[0026] (III) Beneficial effects

[0027] Compared with the prior art, the present invention provides a method for utilizing soluble calcium ions and chloride ions in a supernatant, which has the following beneficial effects:

[0028] 1. The method for treating calcium ions in a supernatant for preparing calcium sulfate or calcium carbonate comprises the following steps: controlling the pH value, determining the calcium ion concentration, and then adding sodium sulfate powder or sodium carbonate powder to make the calcium ions react with sulfate ions or carbonate ions to generate calcium sulfate precipitates or calcium carbonate precipitates, thereby achieving the purpose of removing calcium ions, and the removal rate of calcium ions can be close to 100%.

[0029] 2. The method for treating supernatant calcium ions for preparing calcium sulfate, in the process of preparing calcium sulfate, by adding a sodium sulfate powder, the produced calcium sulfate precipitate or calcium carbonate precipitate can be used for producing gypsum board, and the produced brine (NaCl solution) can be used for industrial production. In the case of adding only one raw material, two raw materials are obtained, thereby achieving the purpose of preparing calcium sulfate or calcium carbonate products and brine, and both can be used for industrial production, and have good application prospects in the actual industrial field. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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.

[0031] Embodiment 1:

[0032] A method for treating soluble calcium ions and chloride ions in a supernatant, comprising the following steps:

[0033] S1: To ensure that the prepared solution does not crystallize and precipitate under different temperature conditions, sodium sulfate is selected and dissolved in deionized water at 0°C, and stirred to disperse into a uniform solution. The uniform solution is divided into three equal parts and placed in beakers respectively;

[0034] S2: Use a 50ml measuring cylinder to take 20ml of the supernatant, then pour the supernatant into a 50ml beaker, add sodium sulfate powder into the beaker and stir with a glass rod to obtain a precipitate;

[0035] S3: Use a vacuum filtration bottle to separate the calcium sulfate or calcium carbonate precipitate from the supernatant, and take three samples, namely the total sample, the sample after filtration and the supernatant, to determine the content of calcium ions and sulfate ions therein.

[0036] The analytical purity of the sodium sulfate in S1 is ≥99.0%, and the supernatant c(Ca 2+ ) is 37.25 g / L. The supernatant in S2 was poured into a 50 ml beaker and stirred for 5 min and then allowed to stand for 10 min.

[0037] The method for determining the calcium ion content comprises the following steps:

[0038] S1: Weigh 20g of sample, accurate to 0.0002g, place in a 250mL beaker, add water to dissolve, transfer all to a 1000mL volumetric flask, mix well, dilute with water to the scale and shake well. This solution is test solution A, for calcium chloride content;

[0039] S2: Pipette 10mL of test solution A into a 250mL conical flask, adjust the pH to 3-5 with hydrochloric acid solution, add water to about 50mL, add 5mL of triethanolamine solution, 2mL of sodium hydroxide solution, and about 0.1g of calcium reagent carboxylate sodium salt indicator, and titrate with disodium ethylenediaminetetraacetic acid standard titration solution. The end point is when the solution changes from red to pure blue;

[0040] S3: Perform a blank test at the same time. Except for not adding test sample, all other reagents added in the blank test are the same as those in the test solution.

[0041] The method for determining the sulfate ion content comprises the following steps:

[0042] S1: Take a certain volume of sample solution, place it in a 400mL beaker, add water to 150mL, add 2 drops of methyl red indicator, add hydrochloric acid solution until the solution turns red, heat to near boiling, quickly add 40mL of hot barium chloride solution, stir vigorously for 2 minutes, and cool to room temperature;

[0043] S2: Add a little barium chloride solution to check whether the precipitation is complete, and filter it with a glass crucible that has been dried and weighed at 120°C in advance. Pour the upper clear liquid into the crucible first, wash the precipitate in the beaker with water several times, and then transfer all the precipitate in the beaker to the crucible;

[0044] S3: Continue washing the precipitate with water several times until the filtrate contains no chloride ions;

[0045] S4: After rinsing the outer wall of the crucible with a small amount of water, dry it in a constant temperature drying oven at 120℃±2℃ for 1h, take it out and weigh it. Then weigh it every 30min of drying until the difference between the two weighings does not exceed 0.0002g. Finally, calculate the sulfate ion content using the formula.

[0046] Solubility of sodium sulfate at different temperatures (unit: g / 100g water)

[0047]

[0048] Theoretical calculations

[0049] The following table shows the Cl content of three samples obtained by experimental determination. - , Ca 2+ Mg 2+ and SO4 2- The content of four ions. It can be seen that c(Ca 2+ )=37.25g / L, that is, c(Ca 2+ )=0.9305mol / L.

[0050] Determination of ion content of three samples

[0051]

[0052] The chemical reactions involved are shown below.

[0053] CaCl2+Na2SO4→CaSO4+2NaCl

[0054] CaCl2+Na2CO3→CaCO3+2NaCl

[0055] Take 20ml of sample as the sample to be precipitated. Then:

[0056] n(Ca 2+ )=0.9305mol / L×0.02L=0.01861mol

[0057] n(Na2SO4)=n(Ca 2+ )=n(CaSO4)=0.01861mol

[0058] The mass of Na2SO4 required is:

[0059] m(Na2SO4)=0.01861mol×142.04g / mol=2.6434g

[0060] Therefore, the raw materials and amounts required for the experiment are shown in the following table.

[0061] Raw material dosage

[0062]

[0063] During the preparation process, samples were taken twice for analysis. The results of the first sampling analysis are as follows:

[0064] Serial number sample Sampling volume Consumption of 3% hydrochloric acid result 1 1# Total Sample 1000 ml 9.0 ml pH about 8.0 2 2# Filter Press 1000 ml 49.0 ml pH about 8.0 3 3# Clarification 1000 ml 50.0 ml pH about 8.0

[0065] The results of the second sampling analysis are as follows:

[0066] Serial number sample Sampling volume Consumption of 3% hydrochloric acid result 1 1# Total Sample 1000 ml 10.5 ml pH about 8.0 2 2# Filter Press 1000 ml 50.6 ml pH about 8.0 3 3# Clarification 1000 ml 51.7 ml pH about 8.0

[0067] Embodiment 2:

[0068] The sodium sulfate powder in step S2 is replaced with sodium carbonate powder, and the remaining steps are the same.

[0069] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating soluble calcium ions and chloride ions in a supernatant, characterized in that: The following steps are involved: S1: Select sodium sulfate and dissolve it in deionized water at 0°C, stir and disperse it into a uniform solution, divide the uniform solution into three equal parts, and put them in beakers respectively; S2: Use a 50ml measuring cylinder to take 20ml of the supernatant, then pour the supernatant into a 50ml beaker, add one of sodium sulfate powder or sodium carbonate powder into the beaker and stir with a glass rod to obtain a precipitate; S3: Use a vacuum filtration bottle to separate the calcium sulfate precipitate from the supernatant, and take three samples, namely the total sample, the sample after filtration and the supernatant, to determine the content of calcium ions and sulfate ions therein.

2. The method for treating soluble calcium ions and chloride ions in a supernatant according to claim 1, characterized in that: The analytical purity of the sodium sulfate in S1 is ≥99.0%, and the supernatant c(Ca 2+ ) is 37.25g / L.

3. The method for treating soluble calcium ions and chloride ions in a supernatant according to claim 1, characterized in that: The supernatant in S2 was poured into a 50 ml beaker and stirred for 5 min and then allowed to stand for 10 min.

4. The method for treating soluble calcium ions and chloride ions in a supernatant according to claim 1, characterized in that: The method for determining the calcium ion content comprises the following steps: S1: Weigh 20g of sample, accurate to 0.0002g, place in a 250mL beaker, add water to dissolve, transfer all to a 1000mL volumetric flask, mix well, dilute with water to the scale and shake well. This solution is test solution A, for calcium chloride content; S2: Pipette 10mL of test solution A into a 250mL conical flask, adjust the pH to 3-5 with hydrochloric acid solution, add water to about 50mL, add 5mL of triethanolamine solution, 2mL of sodium hydroxide solution, and about 0.1g of calcium reagent carboxylate sodium salt indicator, and titrate with disodium ethylenediaminetetraacetic acid standard titration solution. The end point is when the solution changes from red to pure blue; S3: Perform a blank test at the same time. Except for not adding test sample, all other reagents added in the blank test are the same as those in the test solution.

5. The method for treating soluble calcium ions and chloride ions in a supernatant according to claim 1, characterized in that: The method for determining the sulfate ion content comprises the following steps: S1: Take a certain volume of sample solution, place it in a 400mL beaker, add water to 150mL, add 2 drops of methyl red indicator, add hydrochloric acid solution until the solution turns red, heat to near boiling, quickly add 40mL of hot barium chloride solution, stir vigorously for 2 minutes, and cool to room temperature; S2: Add a little barium chloride solution to check whether the precipitation is complete, and filter it with a glass crucible that has been dried and weighed at 120°C in advance. Pour the upper clear liquid into the crucible first, wash the precipitate in the beaker with water several times, and then transfer all the precipitate in the beaker to the crucible; S3: Continue washing the precipitate with water several times until the filtrate contains no chloride ions; S4: After rinsing the outer wall of the crucible with a small amount of water, dry it in a constant temperature drying oven at 120℃±2℃ for 1h, take it out and weigh it. Then weigh it every 30min of drying until the difference between the two weighings does not exceed 0.0002g. Finally, calculate the sulfate ion content using the formula.

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