A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio.

Abstract

This invention relates to a method for treating and utilizing high magnesium-to-sulfur ratio chlorine-containing wastewater, belonging to the field of environmental protection. This invention utilizes inexpensive calcium alkali to treat high magnesium-to-sulfur ratio chlorine-containing wastewater. During the treatment process, dilute hydrochloric acid is used as a circulation starter. Taking advantage of the difficult-to-remove chloride ions in the wastewater, the calcium alkali is used to generate calcium chloride solution, thereby continuously recovering sulfate ions from the high magnesium-to-sulfur ratio wastewater. Magnesium is converted into magnesium hydroxide, transforming into valuable by-products such as calcium chloride and gypsum, thus achieving resource utilization of waste. This method reduces the environmental impact of wastewater discharge, while also reducing treatment costs and achieving resource recycling. It is highly feasible for existing enterprises and has significant economic, social, and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection and relates to a method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio. Background Technology

[0002] In industrial production processes, especially in chemical and metallurgical industries, sulfuric acid and hydrochloric acid are commonly used acidic leaching agents. Hydrochloric acid is also a common detergent. Therefore, wastewater often contains high concentrations of sulfate and chloride ions. Sulfate ions can cause eutrophication, while chloride ions are extremely detrimental to the growth of aquatic organisms. The cations in wastewater are often potassium, sodium, aluminum, magnesium, calcium, copper, zinc, and iron ions. While potassium and sodium ions may require membrane technology for removal, other cations can be removed using various methods and have recycling value, such as neutralization, sulfidation, electrolysis, and resin adsorption.

[0003] Currently, the main methods for treating high magnesium-to-sulfur ratio chlorine-containing wastewater include chemical precipitation, ion exchange, and electrodialysis. Chemical precipitation is a commonly used method, involving the direct addition of soluble calcium salts such as calcium chloride or calcium nitrate to the wastewater to produce calcium sulfate and magnesium chloride solutions. Lime slurry is then added to produce magnesium hydroxide and calcium chloride solutions, which are then circulated back into the wastewater in a continuous cycle. This process significantly increases the volume of water, requiring concentration through evaporation or nanofiltration, resulting in high investment and operating costs. Ion exchange can remove heavy metals, but the ion exchange process has a specific order; for wastewater containing both sulfate and chloride ions, sulfate takes precedence over chloride, potentially requiring frequent replacement of the adsorption resin. Electrodialysis uses an electric field to remove ions from wastewater, achieving water purification, but it consumes a lot of energy, has high operating costs, and the electrodes and membranes are susceptible to fouling and damage, requiring regular maintenance and replacement. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a method for treating and utilizing high magnesium-sulfur ratio chlorine-containing wastewater, which can recycle sulfate, chloride, and magnesium ions in the wastewater, while simultaneously producing qualified gypsum products and magnesium hydroxide, thereby achieving the resource-based treatment of wastewater.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio, comprising the following specific steps:

[0007] (1) Calcium base was added to chlorine-containing wastewater with high magnesium-sulfur ratio for a stage of neutralization. After the reaction was completed, solid-liquid separation was carried out to obtain filter residue 1 and filtrate 1.

[0008] (2) Add hydrochloric acid to the filter residue 1 and stir. The pH of the whole system is 6-7. After the reaction is completed, a calcium chloride magnesium mixed solution and a high-quality gypsum product are obtained.

[0009] (3) Add calcium-based substances to the filtrate 1 for two-stage neutralization. After the reaction is completed, perform solid-liquid separation to obtain magnesium hydroxide product and filtrate 2.

[0010] (4) Add the high magnesium-to-sulfur ratio chlorine-containing wastewater to the filtrate 2. After the reaction is completed, magnesium chloride solution and high-quality gypsum product are obtained.

[0011] Further, the pH range of the high magnesium-sulfur ratio chlorine-containing wastewater in step (1) is 5 to 8, and its sources include, but are not limited to, high magnesium-sulfur ratio chlorine-containing wastewater generated in the flue gas desulfurization process and the neutralization and sulfidation treatment processes of metallurgical industrial wastewater. The magnesium-sulfur molar ratio in the high magnesium-sulfur ratio chlorine-containing wastewater is >1.2, and the sulfate concentration is <40g / L.

[0012] Further, the calcium alkali mentioned in step (1) is calcium oxide, calcium hydroxide, or one or more of the following: carbide slag, acetylene purification waste residue, white mud, green mud, and lime slag, with calcium oxide or calcium hydroxide as the main components, wherein the active calcium oxide content is not less than 60%; the calcium alkali is added in powder form, and the particle size of the calcium alkali is 200-400 mesh, which can absorb water and achieve the effect of concentrating wastewater and preventing the system from overflowing.

[0013] Further, in step (1), the amount of calcium alkali added in the first-stage neutralization reaction is defined as the ratio of calcium oxide content in the calcium alkali to sulfate molar ratio in the wastewater as 1 to 1.2, the stirring speed is 500 to 600 r / min, and the reaction is carried out at room temperature for 30 to 60 min.

[0014] Further, the filter residue 1 in step (1) is a mixture of calcium sulfate, magnesium hydroxide and unreacted calcium alkali; the filtrate 1 is a magnesium chloride solution.

[0015] Furthermore, the concentration of hydrochloric acid in step (2) is 1 mol / L, and the stirring speed is 200 r / min.

[0016] Furthermore, in step (3), the amount of calcium and alkali used in the two-stage neutralization reaction is defined by the pH value of the system reaction endpoint being between 10.5 and 11.0, the stirring speed is 200 to 400 r / min, and the reaction is carried out at room temperature for 60 to 90 min.

[0017] Furthermore, the purity of the magnesium hydroxide product in step (3) is not less than 85%, and the impurities are a small amount of unreacted calcium-alkali mixture; the main component of the filtrate 2 is calcium chloride.

[0018] Furthermore, the product of the sulfur enrichment process in step (4) is calcium sulfate, i.e. gypsum, which also enriches chloride and magnesium ions in the wastewater.

[0019] Furthermore, the sulfur enrichment and collection process in step (4) is carried out at a stirring speed of 150-200 r / min and at room temperature for 15-30 min.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention first utilizes calcium alkali to recover magnesium and sulfate ions from chlorine-containing wastewater with a high magnesium-to-sulfur ratio. Then, it uses the obtained filter residue for acidification, separation, and sulfur enrichment to further obtain magnesium hydroxide and gypsum products, and produces magnesium chloride solution that can be reused in production.

[0022] This invention utilizes inexpensive calcium alkali to treat high magnesium-to-sulfur ratio chlorine-containing wastewater. The treatment process uses dilute hydrochloric acid as a circulation starter. Taking advantage of the persistent chloride ions in the wastewater, the calcium alkali generates a calcium chloride solution, continuously recovering sulfate ions from the high magnesium-to-sulfur ratio wastewater. Magnesium is converted into magnesium hydroxide, transforming into valuable byproducts such as calcium chloride and gypsum, thus achieving resource utilization of waste and improving economic efficiency. The addition of calcium alkali powder concentrates the wastewater. Furthermore, the addition of calcium alkali increases the temperature and causes some water evaporation, preventing the system from overflowing.

[0023] This invention is simple to operate, achieves high magnesium and sulfur recovery rates, and produces high-purity products. The method reduces the environmental impact of wastewater discharge, lowers treatment costs, and enables resource recycling. It is highly feasible for existing enterprises and offers significant economic, social, and environmental benefits. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for resource-based treatment of chlorine-containing wastewater with a high magnesium-to-sulfur ratio according to the present invention. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0026] Example 1

[0027] A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio, such as... Figure 1 As shown, the specific steps are as follows:

[0028] (1) Calcium-alkali neutralization in one step: In this example, the high magnesium-sulfur ratio chlorine-containing wastewater has a pH of 8, a sulfate content of 20 g / L, and a magnesium-sulfur molar ratio of 1.3. 19.44 g of calcium oxide-containing waste residue powder with a content of 60% and a particle size of 200 mesh is added to 1 L of wastewater. The mixture reacts together for 60 min at a stirring speed of 550 r / min. After the reaction is complete, the residue is filtered to obtain filter residue 1 and filtrate 1.

[0029] (2) Acidification separation: Add 1 mol / L hydrochloric acid to the filter residue 1 obtained in step (1), adjust the pH of the system to 6, and stir at 200 r / min. After the reaction is completed, a calcium chloride magnesium mixed solution and high-quality gypsum product are obtained.

[0030] (3) Two-stage neutralization of calcium and alkali: Add calcium-containing waste residue powder with a lime content of 60% to the filtrate 1 obtained in step (1) for two-stage neutralization. React together for 70 min with a stirring speed of 280 r / min. After the reaction is completed, the pH of the system reaches 10.7 and then solid-liquid separation is performed to obtain magnesium hydroxide product and filtrate 2.

[0031] (4) Sulfur enrichment: Add high magnesium-to-sulfur ratio chlorine-containing wastewater to the filtrate 2 obtained in step (2), stir at 160 r / min, react at room temperature for 25 min, and after the reaction is completed, magnesium chloride solution and high-quality gypsum product are obtained with a gypsum purity of 98%.

[0032] Example 2

[0033] A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio, comprising the following specific steps:

[0034] (1) Calcium-alkali neutralization in one step: In this example, the high magnesium-sulfur ratio chlorine-containing wastewater has a pH of 7.5, a sulfate content of 25 g / L, and a magnesium-sulfur molar ratio of 1.4. 24.31 g of calcium-containing waste residue powder with a calcium oxide content of 60% and a particle size of 250 mesh is added to 1 L of wastewater. The mixture is reacted together for 50 min at a stirring speed of 600 r / min. After the reaction is complete, the residue is filtered to obtain filter residue 1 and filtrate 1.

[0035] (2) Acidification separation: Add 1 mol / L hydrochloric acid to the filter residue 1 obtained in step (1), adjust the pH of the system to 6.2, and stir at 200 r / min. After the reaction is completed, a calcium chloride magnesium mixed solution and a high-quality gypsum product are obtained.

[0036] (3) Two-stage neutralization of calcium and alkali: Add calcium-containing waste residue powder with a lime content of 60% to the filtrate 1 obtained in step (1) for two-stage neutralization. React together for 80 min with a stirring speed of 300 r / min. After the reaction is completed, the pH of the system reaches 10.5 and then solid-liquid separation is performed to obtain magnesium hydroxide product and filtrate 2.

[0037] (4) Sulfur enrichment: Add high magnesium-to-sulfur ratio chlorine-containing wastewater to the filtrate 2 obtained in step (2), stir at 180 r / min, react at room temperature for 20 min, and after the reaction is completed, magnesium chloride solution and high-quality gypsum product are obtained with gypsum purity of 99%.

[0038] Example 3

[0039] A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio, comprising the following specific steps:

[0040] (1) Calcium-alkali neutralization: In this example, the high magnesium-sulfur ratio chlorine-containing wastewater has a pH of 8, a sulfate content of 21 g / L, and a magnesium-sulfur molar ratio of 1.5. 20.42 g of calcium oxide-containing waste residue powder with a content of 60% and a particle size of 300 mesh is added to 1 L of wastewater. The mixture reacts together for 55 min at a stirring speed of 510 r / min. After the reaction is complete, the residue is filtered to obtain filter residue 1 and filtrate 1.

[0041] (2) Acidification separation: Add 1 mol / L hydrochloric acid to the filter residue 1 obtained in step (1), adjust the pH of the system to 6.3, and stir at 200 r / min. After the reaction is completed, a calcium chloride magnesium mixed solution and high-quality gypsum product are obtained.

[0042] (3) Two-stage neutralization of calcium and alkali: Add calcium-containing waste residue powder with a lime content of 60% to the filtrate 1 obtained in step (1) for two-stage neutralization. React together for 80 min with a stirring speed of 290 r / min. After the reaction is completed, the pH of the system reaches 10.8 and then solid-liquid separation is performed to obtain magnesium hydroxide product and filtrate 2.

[0043] (4) Sulfur enrichment: Add high magnesium-sulfur ratio chlorine-containing wastewater to the filtrate 2 obtained in step (2), stir at 175 r / min, react at room temperature for 30 min, and after the reaction is completed, magnesium chloride solution and high-quality gypsum product are obtained with a gypsum purity of 97%.

[0044] Example 4

[0045] A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio, comprising the following specific steps:

[0046] (1) Calcium-alkali neutralization: In this example, the high magnesium-sulfur ratio chlorine-containing wastewater has a pH of 7.8, a sulfate content of 24 g / L, and a magnesium-sulfur molar ratio of 1.4. 23.33 g of calcium-containing waste residue powder with a calcium oxide content of 60% and a particle size of 350 mesh is added to 1 L of wastewater. The mixture reacts together for 45 min at a stirring speed of 580 r / min. After the reaction is complete, the residue is filtered to obtain filter residue 1 and filtrate 1.

[0047] (2) Acidification separation: Add 1 mol / L hydrochloric acid to the filter residue 1 obtained in step (1), adjust the pH of the system to 6.1, and stir at 200 r / min. After the reaction is completed, a calcium chloride magnesium mixed solution and high-quality gypsum product are obtained.

[0048] (3) Two-stage neutralization of calcium and alkali: Add calcium-containing waste residue powder with a lime content of 60% to the filtrate 1 obtained in step (1) for two-stage neutralization. React together for 85 min with a stirring speed of 320 r / min. After the reaction is completed, the pH of the system reaches 10.6 and then solid-liquid separation is performed to obtain magnesium hydroxide product and filtrate 2.

[0049] (4) Sulfur enrichment: Add high magnesium-sulfur ratio chlorine-containing wastewater to the filtrate 2 obtained in step (2), stir at 160 r / min, react at room temperature for 25 min, and after the reaction is completed, magnesium chloride solution and high-quality gypsum product are obtained with a gypsum purity of 96%.

[0050] Example 5

[0051] A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio, comprising the following specific steps:

[0052] (1) Calcium-alkali neutralization: In this example, the high magnesium-sulfur ratio chlorine-containing wastewater has a pH of 8, a sulfate content of 22 g / L, and a magnesium-sulfur molar ratio of 1.6. 21.39 g of calcium-containing waste residue powder with a calcium oxide content of 60% and a particle size of 400 mesh is added to 1 L of wastewater. The mixture reacts together for 30 min at a stirring speed of 590 r / min. After the reaction is complete, the residue is filtered to obtain filter residue 1 and filtrate 1.

[0053] (2) Acidification separation: Add 1 mol / L hydrochloric acid to the filter residue 1 obtained in step (1), adjust the pH of the system to 6.8, and stir at 200 r / min. After the reaction is completed, a calcium chloride magnesium mixed solution and high-quality gypsum product are obtained.

[0054] (3) Two-stage neutralization of calcium and alkali: Add calcium-containing waste residue powder with a lime content of 60% to the filtrate 1 obtained in step (1) for two-stage neutralization. React together for 65 min with a stirring speed of 400 r / min. After the reaction is completed, the pH of the system reaches 10.9 and then solid-liquid separation is performed to obtain magnesium hydroxide product and filtrate 2.

[0055] (4) Sulfur enrichment: Add high magnesium-sulfur ratio chlorine-containing wastewater to the filtrate 2 obtained in step (2), stir at 170 r / min, react at room temperature for 25 min, and after the reaction is completed, magnesium chloride solution and high-quality gypsum product are obtained with gypsum purity of 95%.

[0056] Example 6

[0057] A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio, comprising the following specific steps:

[0058] (1) Calcium-alkali neutralization: In this example, the high magnesium-sulfur ratio chlorine-containing wastewater has a pH of 7.5, a sulfate content of 26 g / L, and a magnesium-sulfur molar ratio of 1.7. 25.28 g of calcium-containing waste residue powder with a calcium oxide content of 60% and a particle size of 200 mesh is added to 1 L of wastewater. The mixture reacts together for 60 min at a stirring speed of 550 r / min. After the reaction is complete, the residue is filtered to obtain filter residue 1 and filtrate 1.

[0059] (2) Acidification separation: Add 1 mol / L hydrochloric acid to the filter residue 1 obtained in step (1), adjust the pH of the system to 6.2, and stir at 200 r / min. After the reaction is completed, a calcium chloride magnesium mixed solution and a high-quality gypsum product are obtained.

[0060] (3) Two-stage neutralization of calcium and alkali: Add calcium-containing waste residue powder with a lime content of 60% to the filtrate 1 obtained in step (1) for two-stage neutralization. React together for 70 min with a stirring speed of 280 r / min. After the reaction is completed, the pH of the system reaches 11.0 and then solid-liquid separation is performed to obtain magnesium hydroxide product and filtrate 2.

[0061] (4) Sulfur enrichment: Add high magnesium-sulfur ratio chlorine-containing wastewater to the filtrate 2 obtained in step (2), stir at 160 r / min, react at room temperature for 25 min, and after the reaction is completed, magnesium chloride solution and high-quality gypsum product are obtained with a gypsum purity of 97%.

[0062] Example 7

[0063] A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio, comprising the following specific steps:

[0064] (1) Calcium-alkali neutralization in one step: In this example, the high magnesium-sulfur ratio chlorine-containing wastewater has a pH of 6, a sulfate content of 30 g / L, and a magnesium-sulfur molar ratio of 1.3. 29.17 g of calcium-containing waste residue powder with a calcium oxide content of 60% and a particle size of 300 mesh is added to 1 L of wastewater. The mixture reacts together for 40 min at a stirring speed of 530 r / min. After the reaction is complete, the residue is filtered to obtain filter residue 1 and filtrate 1.

[0065] (2) Acidification separation: Add 1 mol / L hydrochloric acid to the filter residue 1 obtained in step (1), adjust the pH of the system to 6.6, and stir at 200 r / min. After the reaction is completed, a calcium chloride magnesium mixed solution and high-quality gypsum product are obtained.

[0066] (3) Two-stage neutralization of calcium and alkali: Add calcium-containing waste residue powder with a lime content of 60% to the filtrate 1 obtained in step (1) for two-stage neutralization. React together for 75 min with a stirring speed of 350 r / min. After the reaction is completed, the pH of the system reaches 11.0 and then solid-liquid separation is performed to obtain magnesium hydroxide product and filtrate 2.

[0067] (4) Sulfur enrichment: Add high magnesium-sulfur ratio chlorine-containing wastewater to the filtrate 2 obtained in step (2), stir at 160 r / min, react at room temperature for 28 min, and after the reaction is completed, magnesium chloride solution and high-quality gypsum product are obtained with gypsum purity of 98%.

[0068] Example 8

[0069] A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio, comprising the following specific steps:

[0070] (1) Calcium-alkali neutralization: In this example, the high magnesium-sulfur ratio chlorine-containing wastewater has a pH of 5, a sulfate content of 32 g / L, and a magnesium-sulfur molar ratio of 1.8. 31.11 g of calcium-containing waste residue powder with a calcium oxide content of 60% and a particle size of 200 mesh will be added to 1 L of wastewater. The mixture will react together for 60 min at a stirring speed of 560 r / min. After the reaction is complete, the mixture will be filtered to obtain filter residue 1 and filtrate 1.

[0071] (2) Acidification separation: Add 1 mol / L hydrochloric acid to the filter residue 1 obtained in step (1), adjust the pH of the system to 6.5, and stir at 200 r / min. After the reaction is completed, a calcium chloride magnesium mixed solution and high-quality gypsum product are obtained.

[0072] (3) Two-stage neutralization of calcium and alkali: Add calcium-containing waste residue powder with a lime content of 60% to the filtrate 1 obtained in step (1) for two-stage neutralization. React together for 75 min with a stirring speed of 290 r / min. After the reaction is completed, the pH of the system reaches 10.5 and then solid-liquid separation is performed to obtain magnesium hydroxide product and filtrate 2.

[0073] (4) Sulfur enrichment: Add high magnesium-sulfur ratio chlorine-containing wastewater to the filtrate 2 obtained in step (2), stir at 165 r / min, react at room temperature for 20 min, and after the reaction is completed, magnesium chloride solution and high-quality gypsum product are obtained with gypsum purity of 99%.

Claims

1. A method for treating and utilizing chlorine-containing wastewater with a high magnesium-to-sulfur ratio, characterized in that, The specific steps are as follows: (1) Calcium base was added to the chlorine-containing wastewater with a high magnesium-to-sulfur ratio for a stage of neutralization. After the reaction was completed, solid-liquid separation was carried out to obtain filter residue 1 and filtrate 1. (2) Add 1 mol / L hydrochloric acid to the filter residue 1, stir at 200 r / min, adjust the pH of the system to 6~7, and after the reaction is completed, obtain calcium chloride magnesium mixed solution and high-quality gypsum product; (3) Add calcium base to the filtrate 1 for two-stage neutralization. After the reaction is completed, perform solid-liquid separation to obtain magnesium hydroxide product and filtrate 2. (4) Add the high magnesium-to-sulfur ratio chlorine-containing wastewater to the filtrate 2. After the reaction is completed, magnesium chloride solution and high-quality gypsum product are obtained. The pH range of the high magnesium-sulfur ratio chlorine-containing wastewater in step (1) is 5~8. Its sources include, but are not limited to, high magnesium-sulfur ratio chlorine-containing wastewater generated by the flue gas desulfurization process and the neutralization and sulfidation treatment processes of metallurgical industrial wastewater. The magnesium-sulfur molar ratio in the high magnesium-sulfur ratio chlorine-containing wastewater is >1.2 and the sulfate concentration is <40 g / L. The calcium alkali mentioned in step (1) is calcium oxide, calcium hydroxide, or one or more of the following: calcium carbide slag, acetylene purification waste residue, white mud, green mud, lime slag, etc., with calcium oxide or calcium hydroxide as the main components, wherein the active calcium oxide content is not less than 60%; the calcium alkali is added in powder form, and the particle size of the calcium alkali is 200~400 mesh, which can absorb water, achieve the effect of concentrating wastewater, and prevent the system from overflowing.

2. The method for treating and utilizing high magnesium-to-sulfur ratio chlorine-containing wastewater according to claim 1, characterized in that, In step (1), the amount of calcium alkali added is defined by the ratio of calcium oxide content in the calcium alkali to sulfate molar ratio in the wastewater as 1 to 1.

2. The stirring speed is 500 to 600 r / min, and the reaction is carried out at room temperature for 30 to 60 min.

3. The method for treating and utilizing high magnesium-to-sulfur ratio chlorine-containing wastewater according to claim 1, characterized in that, The filter residue 1 in step (1) is a mixture of calcium sulfate, magnesium hydroxide and unreacted calcium alkali; the filtrate 1 is a magnesium chloride solution.

4. The method for treating and utilizing high magnesium-to-sulfur ratio chlorine-containing wastewater according to claim 1, characterized in that, The concentration of hydrochloric acid in step (2) is 1 mol / L, and the stirring speed is 200 r / min.

5. The method for treating and utilizing high magnesium-to-sulfur ratio chlorine-containing wastewater according to claim 1, characterized in that, In step (3), the amount of calcium and alkali used in the two-stage neutralization reaction is defined by the pH value of the system reaction endpoint being between 10.5 and 11.

0. The stirring speed is 200 to 400 r / min, and the reaction is carried out at room temperature for 60 to 90 min.

6. The method for treating and utilizing high magnesium-to-sulfur ratio chlorine-containing wastewater according to claim 1, characterized in that, The purity of the magnesium hydroxide product in step (3) is not less than 85%, and the impurities are a small amount of unreacted calcium-alkali mixture; the main component of the filtrate 2 is calcium chloride.

7. The method for treating and utilizing high magnesium-to-sulfur ratio chlorine-containing wastewater according to claim 1, characterized in that, Step (4) enriches the sulfur recovery process product, which is calcium sulfate, i.e. gypsum, while also enriching chloride and magnesium ions in the wastewater.

8. The method for treating and utilizing high magnesium-to-sulfur ratio chlorine-containing wastewater according to claim 1, characterized in that, Step (4) The sulfur enrichment and collection process involves stirring at a speed of 150~200 r / min and reacting at room temperature for 15~30 min.

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