A method for processing sodium chloride recovered from glycerin sweet water

Abstract

A method for treating sodium chloride recovered from glycerin sweet water comprises: (1) dissolving recovered crude sodium chloride in water to prepare brine, and controlling the temperature of the brine; the crude sodium chloride contains fatty acids and a first water-soluble metal ion group, the first water-soluble metal ion group including a first oxidizable metal ion but not including sodium ions; (2) adding an oxidant to the brine to oxidize the first metal ion to a second metal ion and oxidize the unsaturated components in the fatty acid; (3) adjusting the pH value with an inorganic base, and reacting the inorganic base with the fatty acid and the water-soluble metal ions other than sodium ions to form a precipitate, the precipitate including fatty acid metal soap and / or metal hydroxide; (4) adding a physical adsorbent; and (5) removing the physical adsorbent and the precipitate to obtain a refined sodium chloride solution. The treatment method of the present application can significantly reduce the content of fatty acids and water-soluble metal ions other than sodium ions in the crude sodium chloride.

Description

Technical Field

[0001] The present application relates to, but is not limited to, soap-making wastewater treatment technology, and in particular to a method for treating sodium chloride recovered from glycerin sweet water. Background Art

[0002] At present, in the soap-making industry, a large amount of glycerin sweet water is produced during the hydrolysis of oils and the continuous saponification. The glycerin sweet water mainly contains water, glycerin, organic matter, and sodium chloride. In order to recycle the glycerin in the glycerin sweet water, the main process currently used is to first purify the glycerin sweet water, then evaporate and concentrate it to separate a large amount of sodium chloride, and then concentrate the crude glycerin to obtain the finished glycerin through distillation and bleaching. Among them, the purification of glycerin sweet water is a key step in controlling the quality of glycerin. Commonly used methods include lime milk method, ferric chloride method, barium hydroxide treatment method, and sodium metaaluminate treatment method. These treatment methods each have their own advantages and disadvantages, but they all inevitably leave some low-carbon fatty acid organic matter and metal ions other than sodium ions, such as iron, calcium, magnesium, barium, and aluminum, in the recovered sodium chloride.

[0003] If the recovered sodium chloride is directly discharged as waste residue or wastewater, its high salt content makes it difficult to treat using biological processes, membrane separation, electrodialysis separation, and capacitive adsorption separation. It may also cause severe corrosion to the treatment equipment, resulting in difficult and costly treatment. If the recovered sodium chloride is directly reused in the soap production process, as mentioned above, the metal ions and low-carbon fatty acids inevitably introduced during the glycerol sweetening water treatment will eventually accumulate in the separated sodium chloride solution. After reuse, fatty acid calcium and fatty acid iron will be generated during the soap-making reaction, significantly reducing the quality of the soap. For example, the whiteness will decrease, the odor will deteriorate, the washing effect will decrease, and the product stability will decrease.

[0004] Currently, there is no dedicated process for treating sodium chloride recovered from glycerin sweetened water. However, as a key raw material in industries such as soap making, sodium chloride has a high recycling value. Therefore, effectively treating sodium chloride recovered from glycerin sweetened water for its recovery and reuse is of great importance. Summary of the Invention

[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of protection of this application.

[0006] The present application embodiment provides a method for treating sodium chloride recovered from glycerin sweetened water, comprising:

[0007] (1) dissolving crude sodium chloride recovered from glycerin sweet water in water to prepare brine, and controlling the temperature of the brine; wherein the crude sodium chloride contains fatty acids and a first water-soluble metal ion group, wherein the first water-soluble metal ion group includes a first metal ion that can be oxidized but does not include sodium ions;

[0008] (2) adding an oxidant to the salt water to carry out an oxidation reaction, so that the first metal ion is oxidized to a second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute a second water-soluble metal ion group;

[0009] (3) adjusting the pH value of the system obtained in step (2) with an inorganic base, and reacting the inorganic base with the fatty acid in the system and the water-soluble metal ions in the second water-soluble metal ion group to form a precipitate, wherein the precipitate includes fatty acid metal soaps and / or metal hydroxides generated from the water-soluble metal ions in the second water-soluble metal ion group;

[0010] (4) adding a physical adsorbent to the system containing the precipitate obtained in step (3);

[0011] (5) removing the physical adsorbent and precipitate in the system obtained in step (4) to obtain a refined sodium chloride solution.

[0012] In an embodiment of the present application, the oxidant may be selected from any one or more of chlorine, hydrogen peroxide, hypochlorous acid, sodium hypochlorite and sodium percarbonate.

[0013] In an embodiment of the present application, the physical adsorbent may be selected from any one or more of diatomaceous earth, activated carbon, clay and molecular sieve.

[0014] In an embodiment of the present application, in step (3), an inorganic base can be used to adjust the pH value of the system obtained in step (2) to 9 to 11.

[0015] In an embodiment of the present application, the inorganic base may be sodium hydroxide.

[0016] In an embodiment of the present application, the amount of the oxidant used may be 0.2% to 10% of the mass of the crude sodium chloride product.

[0017] In an embodiment of the present application, the amount of the physical adsorbent used may be 0.2% to 10% of the mass of the crude sodium chloride product.

[0018] In an embodiment of the present application, the temperature of the brine can be controlled at 40°C to 80°C in step (1).

[0019] In an embodiment of the present application, step (1) may include: dissolving crude sodium chloride recovered from glycerin sweet water in hot water to prepare brine, and controlling the temperature of the brine by controlling the temperature of the hot water;

[0020] The hot water is obtained by heat exchanging condensed water from glycerin distillation with glycerin steam.

[0021] In an embodiment of the present application, the first water-soluble metal ion group may include Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Any one or more of .

[0022] In an embodiment of the present application, the treatment method may further include: recycling the refined sodium chloride solution into a soap production process.

[0023] The method for treating sodium chloride recovered from the glycerin sweet water in the embodiment of the present application uses an oxidant to oxidize the oxidizable low-valent first metal ions in the brine into high-valent second metal ions, and oxidizes the unsaturated components in the fatty acid organic matter in the brine, thereby destroying the structure of the unsaturated components in the fatty acid organic matter and significantly reducing the solubility of the unsaturated components in the fatty acid organic matter in the brine, so as to facilitate the processing in subsequent steps; at the same time, the fatty acids in the brine are reacted with water-soluble metal ions excluding sodium ions under alkaline conditions to generate fatty acid metal soaps (excluding sodium soaps) and / or metal hydroxides. The fatty acid metal soaps and metal hydroxides have low solubility in the brine and can form flocculent precipitates. The addition of a physical adsorbent can cause the flocculent precipitates to aggregate and settle as quickly as possible, which is conducive to the formation of more fatty acid metal soaps and / or metal hydroxides.

[0024] Therefore, the treatment method of sodium chloride recovered from the glycerin sweetened water of the embodiment of the present application can significantly reduce the content of fatty acids and water-soluble metal ions other than sodium ions in the crude sodium chloride product. For example, the concentration of water-soluble metal ions other than sodium ions in the brine can be reduced from more than 100 ppm to less than 2 ppm. The refined sodium chloride solution obtained after treatment can be directly reused in the front-end soap production process.

[0025] Moreover, the method for treating sodium chloride recovered from the glycerin sweetened water in the embodiment of the present application is simple in process, does not involve electrolysis, has low energy consumption, does not involve extraction, does not use organic solvents, has low processing cost, has little pollution to the environment, and is green and environmentally friendly.

[0026] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. Other advantages of the present application can be realized and obtained by the solutions described in the description. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions and advantages of this application more clear, the embodiments of this application will be described in detail below. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other in any way.

[0028] The present application embodiment provides a method for treating sodium chloride recovered from glycerin sweetened water, comprising:

[0029] (1) dissolving crude sodium chloride recovered from glycerin sweet water in water to prepare brine, and controlling the temperature of the brine; wherein the crude sodium chloride contains fatty acids and a first water-soluble metal ion group, wherein the first water-soluble metal ion group includes a first metal ion that can be oxidized but does not include sodium ions;

[0030] (2) adding an oxidant to the salt water to carry out an oxidation reaction, so that the first metal ion is oxidized to a second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute a second water-soluble metal ion group;

[0031] (3) adjusting the pH value of the system obtained in step (2) with an inorganic base, and reacting the inorganic base with the fatty acid in the system and the water-soluble metal ions in the second water-soluble metal ion group to form a precipitate, wherein the precipitate includes fatty acid metal soaps and / or metal hydroxides generated from the water-soluble metal ions in the second water-soluble metal ion group;

[0032] (4) adding a physical adsorbent to the system containing the precipitate obtained in step (3);

[0033] (5) removing the physical adsorbent and precipitate in the system obtained in step (4) to obtain a refined sodium chloride solution.

[0034] The method for treating sodium chloride recovered from the glycerin sweet water in the embodiment of the present application uses an oxidant to oxidize the oxidizable low-valent first metal ions in the brine into high-valent second metal ions, and oxidizes the unsaturated components in the fatty acid organic matter in the brine, thereby destroying the structure of the unsaturated components in the fatty acid organic matter and significantly reducing the solubility of the unsaturated components in the fatty acid organic matter in the brine, so as to facilitate the processing in subsequent steps; at the same time, the fatty acids in the brine are reacted with water-soluble metal ions excluding sodium ions under alkaline conditions to generate fatty acid metal soaps (excluding sodium soaps) and / or metal hydroxides. The fatty acid metal soaps and metal hydroxides have low solubility in the brine and can form flocculent precipitates. The addition of a physical adsorbent can cause the flocculent precipitates to aggregate and settle as quickly as possible, which is conducive to the formation of more fatty acid metal soaps and / or metal hydroxides.

[0035] Therefore, the treatment method of sodium chloride recovered from the glycerin sweetened water of the embodiment of the present application can significantly reduce the content of fatty acids and water-soluble metal ions other than sodium ions in the crude sodium chloride product. For example, the concentration of water-soluble metal ions other than sodium ions in the brine can be reduced from more than 100 ppm to less than 2 ppm. The refined sodium chloride solution obtained after treatment can be directly reused in the front-end soap production process.

[0036] Moreover, the method for treating sodium chloride recovered from the glycerin sweetened water in the embodiment of the present application is simple in process, does not involve electrolysis, has low energy consumption, does not involve extraction, does not use organic solvents, has low processing cost, has little pollution to the environment, and is green and environmentally friendly.

[0037] In an embodiment of the present application, the temperature of the brine can be controlled at 40°C to 80°C in step (1). For example, the temperature of the brine can be controlled at approximately 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C.

[0038] In an embodiment of the present application, step (1) may include: dissolving crude sodium chloride recovered from glycerin sweet water in hot water to prepare brine, and controlling the temperature of the brine by controlling the temperature of the hot water.

[0039] In an embodiment of the present application, the hot water can be obtained by heat exchanging condensed water from glycerin distillation with glycerin vapor. The temperature of the condensed water from glycerin distillation and the glycerin vapor can be raised to above 40°C to 80°C after heat exchange. Recycling this water as hot water for dissolving crude sodium chloride can reduce energy consumption in the sodium chloride treatment method of the present application.

[0040] In an embodiment of the present application, crude sodium chloride may be dissolved in water at room temperature, and the temperature of the brine may be controlled by heating.

[0041] In an embodiment of the present application, the mass fraction of the brine may be 10% to 22%, for example, 10%, 15%, 20%, 21% or 22%.

[0042] In an embodiment of the present application, the first water-soluble metal ion group may include Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Correspondingly, the second water-soluble metal ion group may include Fe 3+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+Any one or more of .

[0043] In an embodiment of the present application, the oxidant may be selected from any one or more of chlorine, hydrogen peroxide, hypochlorous acid, sodium hypochlorite and sodium percarbonate.

[0044] The amount of the oxidant can be determined based on the content of oxidizable metal ions and fatty acids in the brine. In an embodiment of the present application, the amount of the oxidant can be 0.2% to 10% of the mass of the crude sodium chloride product, for example, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0045] In an embodiment of the present application, an oxidant may be added to the brine under continuous stirring conditions.

[0046] In an embodiment of the present application, in step (3), the pH value of the system obtained in step (2) can be adjusted to 9 to 11 using an inorganic base. For example, the pH value of the system can be adjusted to approximately 9, 9.5, 10, 10.5 or 11.

[0047] In an embodiment of the present application, the inorganic base may be sodium hydroxide, for example, sodium hydroxide solution.

[0048] In an embodiment of the present application, the mass fraction of the sodium hydroxide solution may be 5% to 15%.

[0049] In an embodiment of the present application, the physical adsorbent may be selected from any one or more of diatomaceous earth, activated carbon, clay and molecular sieve.

[0050] The amount of the physical adsorbent used can be determined based on the desired color of the refined sodium chloride solution. In an embodiment of the present application, the amount of the physical adsorbent used can be 0.2% to 10% of the mass of the crude sodium chloride product, for example, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0051] In an embodiment of the present application, after adding the physical adsorbent in step (4), stirring can be continued for 20 minutes to 60 minutes, and then allowed to stand for 10 minutes to 60 minutes to form more flocculent precipitates, and the flocculent precipitates can be aggregated and settled.

[0052] In an embodiment of the present application, step (5) can remove the physical adsorbent and precipitate in the system obtained in step (4) by filtering, and the filtering here can include:

[0053] (5-1) Coarse filtration: The system obtained in step (4) is filtered through a filter to remove the sediment and a portion of the physical adsorbent in the system;

[0054] (5-2) Fine filtration: The filtrate obtained in step (5-1) is passed through a safety filter to filter out the remaining physical adsorbent.

[0055] In an embodiment of the present application, the treatment method may further include: recycling the refined sodium chloride solution into a soap production process.

[0056] In an embodiment of the present application, the method for processing the sodium chloride recovered from the glycerin sweetened water may include:

[0057] (1) dissolving crude sodium chloride recovered from glycerin sweet water in hot water to prepare a brine having a mass fraction of 10% to 22%, and controlling the temperature of the brine to be between 40° C. and 80° C. by controlling the temperature of the hot water; wherein the crude sodium chloride contains fatty acids and a first water-soluble metal ion group, wherein the first water-soluble metal ion group includes a first metal ion capable of being oxidized but does not include sodium ions;

[0058] (2) adding an oxidant to the salt water under continuous stirring conditions to carry out an oxidation reaction, so that the first metal ion is oxidized to a second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute a second water-soluble metal ion group;

[0059] (3) adjusting the pH of the system obtained in step (2) to 9 to 11 using a sodium hydroxide solution having a mass fraction of 5% to 15%, and reacting the sodium hydroxide with the fatty acid in the system and the water-soluble metal ions in the second water-soluble metal ion group to form a precipitate, wherein the precipitate includes fatty acid metal soaps and / or metal hydroxides generated from the water-soluble metal ions in the second water-soluble metal ion group;

[0060] (4) adding a physical adsorbent to the system containing the precipitate obtained in step (3), continuously stirring for 20 to 60 minutes, and then allowing to stand for 10 to 60 minutes;

[0061] (5-1) Coarse filtration: The system obtained in step (4) is filtered through a filter to remove the sediment and a portion of the physical adsorbent in the system;

[0062] (5-2) Fine filtration: The filtrate obtained in step (5-1) is passed through a safety filter to filter out the remaining physical adsorbent to obtain a refined sodium chloride solution;

[0063] (6) recycling the refined sodium chloride solution into the soap production process;

[0064] Wherein, the oxidant can be selected from any one or more of chlorine, hydrogen peroxide, hypochlorous acid, sodium hypochlorite and sodium percarbonate; the amount of the oxidant can be 0.2% to 10% of the mass of the crude sodium chloride;

[0065] The physical adsorbent can be selected from any one or more of diatomaceous earth, activated carbon, clay and molecular sieve; the amount of the physical adsorbent can be 0.2% to 10% of the mass of the crude sodium chloride;

[0066] Example 1

[0067] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained by condensing the distillation of glycerol, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 70 ° C;

[0068] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 4.55 parts of sodium hypochlorite to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0069] (3) adjusting the pH to about 9 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0070] (4) Add 4.55 parts of diatomaceous earth to every 100 parts of crude sodium chloride, continue stirring for 30 minutes, and then let it stand for 60 minutes;

[0071] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0072] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the purified sodium chloride solution obtained in step (5) is ≈110ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈2ppm, and the metal ion removal rate reaches 98.2%, which can be directly reused in the front-end soap production process.

[0073] Example 2

[0074] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the precipitate (including sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained by condensing water from glycerol distillation, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 65 ° C;

[0075] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 6.82 parts of sodium hypochlorite to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0076] (3) adjusting the pH to about 10 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0077] (4) Add 4.55 parts of activated carbon to every 100 parts of crude sodium chloride, continue stirring for 30 minutes, and then let it stand for 60 minutes;

[0078] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0079] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the refined sodium chloride solution obtained in step (5) is ≈150ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions is ≈2ppm, and the removal rate of metal ions (excluding sodium ions) reaches 98.7%, which can be directly reused in the front-end soap production process.

[0080] Example 3

[0081] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (including sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained from the condensed water of glycerol distillation, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 80 ° C;

[0082] (2) keeping stirring constantly, after no obvious undissolved sodium chloride is found in the salt dissolving pool, adding 2.73 parts of sodium percarbonate to every 100 parts of the crude sodium chloride product, and continuing stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0083] (3) adjusting the pH to about 9 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0084] (4) Add 3.64 parts of diatomaceous earth to every 100 parts of crude sodium chloride, continue stirring for 30 minutes, and then let it stand for 60 minutes;

[0085] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0086] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the purified sodium chloride solution obtained in step (5) is ≈130ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈2ppm, and the metal ion removal rate reaches 98.5%, which can be directly reused in the front-end soap production process.

[0087] Example 4

[0088] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained from the condensed water of glycerol distillation, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 60 ° C;

[0089] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 4.55 parts of sodium hypochlorite to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0090] (3) adjusting the pH to about 9 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0091] (4) Add 6.82 parts of activated clay to every 100 parts of crude sodium chloride, stir continuously for 30 minutes, and then let it stand for 60 minutes;

[0092] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0093] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the refined sodium chloride solution obtained in step (5) is ≈120ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈5ppm, and the metal ion removal rate reaches 95.8%, which can be directly reused in the front-end soap production process.

[0094] Example 5

[0095] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained from the condensed water of glycerol distillation, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 60 ° C;

[0096] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 2.27 parts of sodium hypochlorite to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0097] (3) adjusting the pH to about 11 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0098] (4) Add 4.55 parts of diatomaceous earth to every 100 parts of crude sodium chloride, continue stirring for 30 minutes, and then let it stand for 60 minutes;

[0099] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0100] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the purified sodium chloride solution obtained in step (5) is ≈130ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈2ppm, and the metal ion removal rate reaches 98.5%, which can be directly reused in the front-end soap production process.

[0101] Example 6

[0102] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained from the condensed water of glycerol distillation, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 60 ° C;

[0103] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 1.36 parts of sodium hypochlorite to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0104] (3) adjusting the pH to about 11 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0105] (4) Add 2.27 parts of diatomaceous earth to every 100 parts of crude sodium chloride, continue stirring for 30 minutes, and then let it stand for 60 minutes;

[0106] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0107] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the purified sodium chloride solution obtained in step (5) is ≈100ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈5ppm, and the metal ion removal rate reaches 95%, which can be directly reused in the front-end soap production process.

[0108] Example 7

[0109] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained from the condensed water of glycerol distillation, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 60 ° C;

[0110] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 0.21 parts of sodium hypochlorite to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0111] (3) adjusting the pH to about 11 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0112] (4) Add 0.21 parts of diatomaceous earth to every 100 parts of crude sodium chloride, continue stirring for 30 minutes, and then let it stand for 60 minutes;

[0113] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0114] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the purified sodium chloride solution obtained in step (5) is ≈90ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+The concentration of metal ions (excluding sodium ions) is ≈8ppm, and the metal ion removal rate reaches 91%, which can be directly reused in the front-end soap production process.

[0115] Example 8

[0116] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained from the condensed water of glycerol distillation, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 60 ° C;

[0117] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 0.21 parts of sodium hypochlorite to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0118] (3) adjusting the pH to about 11 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0119] (4) Add 10 parts of diatomaceous earth to every 100 parts of crude sodium chloride, stir continuously for 30 minutes, and then let it stand for 60 minutes;

[0120] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0121] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the purified sodium chloride solution obtained in step (5) is ≈110ppm. 3+ 、Fe2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈7ppm, and the metal ion removal rate reaches 93%, which can be directly reused in the front-end soap production process.

[0122] Example 9

[0123] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained from the condensed water of glycerol distillation, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 60 ° C;

[0124] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 10 parts of sodium hypochlorite to every 100 parts of crude sodium chloride, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than sodium ions in the obtained system constitute a second water-soluble metal ion group;

[0125] (3) adjusting the pH to about 11 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0126] (4) Add 10 parts of diatomaceous earth to every 100 parts of crude sodium chloride, stir continuously for 30 minutes, and then let it stand for 60 minutes;

[0127] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0128] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba2+ and Al 3+ The concentration of Fe in the purified sodium chloride solution obtained in step (5) is ≈140ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈2ppm, and the metal ion removal rate reaches 98%, which can be directly reused in the front-end soap production process.

[0129] Example 10

[0130] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained from the condensed water of glycerol distillation, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 60 ° C;

[0131] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 10 parts of sodium percarbonate to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0132] (3) adjusting the pH to about 11 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0133] (4) Add 10 parts of diatomaceous earth to every 100 parts of crude sodium chloride, stir continuously for 30 minutes, and then let it stand for 60 minutes;

[0134] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0135] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the refined sodium chloride solution obtained in step (5) is ≈145ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈3ppm, and the metal ion removal rate reaches 97%, which can be directly reused in the front-end soap production process.

[0136] Comparative Example 1

[0137] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained by condensing the distillation of glycerol, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 70 ° C;

[0138] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 0.1 parts of sodium hypochlorite to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0139] (3) adjusting the pH to about 9 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0140] (4) Add 4.55 parts of diatomaceous earth to every 100 parts of crude sodium chloride, continue stirring for 30 minutes, and then let it stand for 60 minutes;

[0141] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0142] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the purified sodium chloride solution obtained in step (5) is ≈110ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈70 ppm, and the metal ion removal rate is only 36.3%, which does not meet the conditions for recycling to the front-end soap production process.

[0143] Comparative Example 2

[0144] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained by condensing the distillation of glycerol, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 70 ° C;

[0145] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 4.55 parts of sodium hypochlorite to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0146] (3) adjusting the pH to about 9 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0147] (4) Add 0.1 parts of diatomaceous earth to every 100 parts of crude sodium chloride, stir continuously for 30 minutes, and then let it stand for 60 minutes;

[0148] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0149] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the purified sodium chloride solution obtained in step (5) is ≈110ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈50ppm, and the metal ion removal rate is only 54.5%, which does not meet the conditions for recycling to the front-end soap production process.

[0150] Comparative Example 3

[0151] (1) 500 kg of crude sodium chloride recovered from glycerol sweet water (containing the first water-soluble metal ion group, where the first water-soluble metal ion group includes the first metal ion (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ Pour the condensed water (such as sodium ions, etc.) into the salt dissolving pool, add 1800 kg of hot water obtained by condensing the distillation of glycerol, start stirring for 1 hour, and prepare a brine with a mass fraction of about 22%, and control the temperature of the brine at 70 ° C;

[0152] (2) Keep stirring constantly, and after no obvious undissolved sodium chloride is found in the salt dissolving pool, add 4.55 parts of sodium hypochlorite to every 100 parts of the crude sodium chloride product, and continue stirring for 1 hour, so that the first metal ion is oxidized to the second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than the sodium ion in the obtained system constitute the second water-soluble metal ion group;

[0153] (3) adjusting the pH to about 8 with a 10% by mass sodium hydroxide solution, and continuing stirring for 1 hour to allow the fatty acids in the brine, the water-soluble metal ions in the second water-soluble metal ion group, and the sodium hydroxide to react to form fatty acid metal soaps and metal hydroxides, which form flocculent precipitates;

[0154] (4) Add 4.55 parts of diatomaceous earth to every 100 parts of crude sodium chloride, continue stirring for 30 minutes, and then let it stand for 60 minutes;

[0155] (5) The solution obtained in step (4) is filtered through a filter. The filtrate is then filtered through a safety filter to remove a small amount of adsorbent and then stored in a brine tank. The treated brine can be directly reused in the front-end soap production process.

[0156] The water-soluble metal ions (Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of Fe in the purified sodium chloride solution obtained in step (5) is ≈110ppm. 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ The concentration of metal ions (excluding sodium ions) is ≈55ppm, and the metal ion removal rate is only 50%, which does not meet the conditions for recycling to the front-end soap production process.

[0157] Although the embodiments disclosed in this application are as described above, the contents described are merely embodiments adopted to facilitate understanding of this application and are not intended to limit this application. Any person skilled in the art to which this application belongs may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application, but the scope of protection of this application shall still be based on the scope defined by the attached claims.

Claims

1. A method for treating sodium chloride recovered from glycerin sweetened water, characterized in that: include: (1) dissolving crude sodium chloride recovered from glycerin sweet water in water to prepare brine, and controlling the temperature of the brine to be between 40° C. and 80° C.; wherein the crude sodium chloride contains fatty acids and a first water-soluble metal ion group, wherein the first water-soluble metal ion group includes a first metal ion capable of being oxidized but does not include sodium ions; (2) adding an oxidant to the salt water to carry out an oxidation reaction, so that the first metal ion is oxidized to a second metal ion, and the unsaturated components in the fatty acid are oxidized, and the water-soluble metal ions other than sodium ions in the obtained system constitute a second water-soluble metal ion group; wherein the amount of the oxidant used is 0.2% to 10% of the mass of the crude sodium chloride product; (3) adjusting the pH of the system obtained in step (2) to 9 to 11 with an inorganic base, and reacting the inorganic base with the fatty acid in the system and the water-soluble metal ions in the second water-soluble metal ion group to form a precipitate, wherein the precipitate includes fatty acid metal soaps and / or metal hydroxides generated from the water-soluble metal ions in the second water-soluble metal ion group; (4) adding a physical adsorbent to the system containing the precipitate obtained in step (3); wherein the amount of the physical adsorbent is 0.2% to 10% of the mass of the crude sodium chloride product; (5) Removing the physical adsorbent and precipitate from the system obtained in step (4) to obtain a refined sodium chloride solution.

2. The processing method according to claim 1, wherein The oxidant is selected from any one or more of chlorine, hydrogen peroxide, hypochlorous acid, sodium hypochlorite and sodium percarbonate.

3. The processing method according to claim 1, wherein: The physical adsorbent is selected from any one or more of diatomaceous earth, activated carbon, clay and molecular sieve.

4. The processing method according to claim 1, wherein: The inorganic base in step (3) is sodium hydroxide.

5. The processing method according to claim 1, wherein: Step (1) comprises: dissolving crude sodium chloride recovered from glycerin sweet water in hot water to prepare brine, and controlling the temperature of the brine by controlling the temperature of the hot water; The hot water is obtained by heat exchanging condensed water from glycerin distillation with glycerin steam.

6. The processing method according to claim 1, wherein: The first water-soluble metal ion group includes Fe 2+ .

7. The processing method according to claim 1, wherein: The first water-soluble metal ion group includes Fe 3+ 、Fe 2+ , Ca 2+ Mg 2+ 、Ba 2+ and Al 3+ .

8. The processing method according to claim 1, further comprising: The refined sodium chloride solution is recycled into the soap production process.