Crystal purification method of high-organic sodium chloride industrial salt

Abstract

The invention belongs to the technical field of resource recycling, and particularly relates to a crystal purification method of high-organic sodium chloride industrial salt. The method comprises the following steps: mixing high-organic sodium chloride industrial salt, a first mother solution and a detergent, and carrying out multi-stage countercurrent ultrasonic washing and multi-stage solid-liquid separation. The multi-stage countercurrent ultrasonic washing technology is adopted to perform crystal purification on the high-organic sodium chloride industrial salt, the cavitation effect of ultrasonic waves is utilized, the permeation effect of a detergent is promoted, organic impurities and salt crystals are effectively stripped, the organic impurities in the salt can be efficiently separated out in an energy-saving mode, the washing effect is improved, and the product quality is improved. The TOC content of the obtained sodium chloride purified crystal is reduced, the yield is improved, the requirement of chlor-alkali salt is met, the refining cost is reduced, and the operation cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of resource recycling, and in particular relates to a method for purifying a crystal of a high-organic sodium chloride industrial salt. Background Art

[0002] High-organic sodium chloride industrial salt is very common in chemical production and is produced in large quantities. The best way to deal with it is to recycle resources. The ideal way to recycle it is to return it to industrial raw materials to prepare chlor-alkali and soda ash. However, due to the high content of organic impurities in high-organic sodium chloride industrial salt, it requires a complex refining process to be processed, otherwise it will have a serious impact on the production process, which seriously restricts the feasibility of its recycling. The refining of a small amount of inorganic part in high-organic sodium chloride industrial salt usually adopts physical separation of thermal or freezing crystallization technology, membrane separation technology or chemical reaction precipitation, while the organic part is removed by incineration, pyrolysis, oxidation and other methods. However, due to factors such as oxidation efficiency and cost control, a single process often cannot achieve a good refining effect.

[0003] Existing refining technologies often use a variety of combined processes for refining. For organic industrial salts, high-energy consumption combined processes based on incineration or pyrolysis represent high energy consumption and high costs, and the final crystalline salt still contains trace amounts of difficult-to-decompose organic matter that cannot be completely treated; in processes based on physical separation, the adsorption process has the problem of poor adsorbent regeneration treatment effect, and oxidation and membrane separation have defects such as poor selectivity and limited separation efficiency. Compared with the above refining processes, the washing process is the most cost-effective refining process, but the conventional refining washing process generally only uses the addition of water and mixing and centrifugation as the main means, which cannot effectively remove organic impurities trapped between crystals or adsorbed on the surface. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for purifying crystals of high-organic sodium chloride industrial salt, which can improve the washing effect, reduce the TOC content of the obtained sodium chloride purified crystals, increase the yield, and reduce the refining cost.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for purifying a crystal of a high-organic sodium chloride industrial salt, comprising the following steps:

[0007] Mixing high-organic sodium chloride industrial salt, a first mother liquor and a detergent, and sequentially performing a first ultrasonic washing and a first solid-liquid separation to obtain a first separation mother liquor and a first separation crystal, respectively;

[0008] The first separated crystals and the second mother liquor are mixed, and a second ultrasonic washing and a second solid-liquid separation are sequentially performed to obtain a second separated mother liquor and a second separated crystal, respectively;

[0009] The second separated crystals and the third mother liquor are mixed, and a third ultrasonic washing and a third solid-liquid separation are sequentially performed to obtain a third separated mother liquor and a sodium chloride purified crystal, respectively;

[0010] The first separated mother liquor is reused as the first mother liquor; before the first separated mother liquor is generated, the first mother liquor is fresh washing water;

[0011] The second separated mother liquor is firstly recycled as the second mother liquor, and the remainder is recycled as the first mother liquor; before the second separated mother liquor is generated, the second mother liquor is fresh washing water;

[0012] The third separated mother liquor is first reused as the third mother liquor, and the remainder is reused as the second mother liquor and the first mother liquor in sequence; the third mother liquor includes supplemented fresh washing water and the third separated mother liquor; before the third separated mother liquor is generated, the third mother liquor is all fresh washing water.

[0013] Preferably, the ultrasonic frequency of the first ultrasonic washing is 20 to 28 kHz; the ultrasonic frequency of the second ultrasonic washing is 28 to 50 kHz; the ultrasonic frequency of the third ultrasonic washing is 50 to 80 kHz; the ultrasonic frequencies of the first ultrasonic washing and the second ultrasonic washing are not the same, and the ultrasonic frequencies of the second ultrasonic washing and the third ultrasonic washing are not the same.

[0014] Preferably, the detergent is an anionic surfactant.

[0015] Preferably, the concentration of the detergent in the mixed solution obtained by mixing the high-organic sodium chloride industrial salt, the first mother liquor and the detergent is 10 to 200 mg / L.

[0016] Preferably, the aperture of the sieve used for the first solid-liquid separation is 100-300 μm; the aperture of the sieve used for the second solid-liquid separation is 50-120 μm; and the aperture of the sieve used for the third solid-liquid separation is 30-60 μm.

[0017] Preferably, the mass ratio of the first mother liquor to the high-organic sodium chloride industrial salt is (1-2):1; the mass ratio of the second mother liquor to the high-organic sodium chloride industrial salt is (1-2):1; the mass ratio of the third mother liquor to the high-organic sodium chloride industrial salt is (1-2):1; the mass ratio of the supplemented fresh washing water to the high-organic sodium chloride industrial salt is (0.5-1):1.

[0018] Preferably, the first ultrasonic cleaning, the second ultrasonic cleaning and the third ultrasonic cleaning are all carried out under stirring conditions; the stirring rate is independently 20 to 80 rpm.

[0019] Preferably, the time for the first ultrasonic cleaning, the second ultrasonic cleaning and the third ultrasonic cleaning is independently 15 to 60 minutes.

[0020] Preferably, the temperatures of the first ultrasonic cleaning, the second ultrasonic cleaning and the third ultrasonic cleaning are independently 35-60°C.

[0021] Preferably, the fresh washing water is one or more of condensed water recycling water, soft water and demineralized water; the TOC of the fresh washing water is less than 1 mg / L.

[0022] The invention provides a method for purifying a crystal of a high-organic sodium chloride industrial salt. The method comprises the following steps: mixing the high-organic sodium chloride industrial salt, a first mother liquor and a detergent, and sequentially performing a first ultrasonic washing and a first solid-liquid separation to obtain a first separated mother liquor and a first separated crystal respectively; mixing the first separated crystal and a second mother liquor, and sequentially performing a second ultrasonic washing and a second solid-liquid separation to obtain a second separated mother liquor and a second separated crystal respectively; mixing the second separated crystal and a third mother liquor, and sequentially performing a third ultrasonic washing and a third solid-liquid separation to obtain a third separated mother liquor and a sodium chloride purified crystal respectively; the first separated mother liquor is reused as the first mother liquor; before the first separated mother liquor is generated, the first mother liquor is fresh washing water; the second separated mother liquor is first reused as the second mother liquor, and the remainder is reused as the first mother liquor; before the second separated mother liquor is generated, the second mother liquor is fresh washing water; the third separated mother liquor is first reused as the third mother liquor, and the remainder is sequentially reused as the second mother liquor and the first mother liquor; the third mother liquor comprises supplemented fresh washing water and the third separated mother liquor; before the third separated mother liquor is generated, the third mother liquor is all fresh washing water.

[0023] The invention adopts a multi-stage countercurrent ultrasonic washing technology to purify the crystals of high-organic sodium chloride industrial salt, utilizes the cavitation effect of ultrasonic waves to promote the penetration of detergents, so that organic impurities are effectively stripped from salt crystals, can separate organic impurities in salt in an energy-saving and efficient manner, improve the washing effect, reduce the TOC content of the obtained sodium chloride purified crystals and improve the yield, so that the requirements for chlor-alkali salt are met, the refining cost is reduced, and the operating cost is reduced.

[0024] Furthermore, the present invention adopts a frequency-grading method for ultrasonic cleaning, first using low-frequency and high-energy-density ultrasonic waves for high-intensity auxiliary cleaning, aiming to break the state of polycrystalline agglomeration and then using high-frequency ultrasonic waves for refined cleaning to improve the cleaning effect.

[0025] Furthermore, the solid-liquid separation in the present invention adopts a graded centrifugal filtration design, mainly because as the salt crystal particle size gradually becomes smaller during the ultrasonic washing process, the accuracy of the separation filtration gradually decreases. The graded centrifugal method is used to best meet the balance between the crystal moisture content, the centrifugal salt leakage rate and the processing capacity, reduce the TOC content of the obtained sodium chloride purified crystals and improve the yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a flow chart of the method for purifying the crystals of high-organic sodium chloride industrial salt in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention provides a method for purifying a crystal of a high-organic sodium chloride industrial salt, comprising the following steps:

[0028] Mixing high-organic sodium chloride industrial salt, a first mother liquor and a detergent, and sequentially performing a first ultrasonic washing and a first solid-liquid separation to obtain a first separation mother liquor and a first separation crystal, respectively;

[0029] The first separated crystals and the second mother liquor are mixed, and a second ultrasonic washing and a second solid-liquid separation are sequentially performed to obtain a second separated mother liquor and a second separated crystal, respectively;

[0030] The second separated crystals and the third mother liquor are mixed, and a third ultrasonic washing and a third solid-liquid separation are sequentially performed to obtain a third separated mother liquor and a sodium chloride purified crystal, respectively;

[0031] The first separated mother liquor is reused as the first mother liquor; before the first separated mother liquor is generated, the first mother liquor is fresh washing water;

[0032] The second separated mother liquor is firstly recycled as the second mother liquor, and the remainder is recycled as the first mother liquor; before the second separated mother liquor is generated, the second mother liquor is fresh washing water;

[0033] The third separated mother liquor is first reused as the third mother liquor, and the remainder is reused as the second mother liquor and the first mother liquor in sequence; the third mother liquor includes supplemented fresh washing water and the third separated mother liquor; before the third separated mother liquor is generated, the third mother liquor is all fresh washing water.

[0034] Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used in the preparation, and commercially available products known to those skilled in the art can be used.

[0035] The invention mixes high-organic sodium chloride industrial salt, a first mother liquor and a detergent, and sequentially performs a first ultrasonic washing and a first solid-liquid separation to obtain a first separation mother liquor and a first separation crystal respectively.

[0036] As an embodiment, the first separated mother liquor is reused as the first mother liquor; before the first separated mother liquor is generated, the first mother liquor is fresh washing water.

[0037] As an implementation mode, the fresh washing water is one or more of condensed water recycling water, soft water and desalted water. As another implementation mode, it can be desalted water. In a specific embodiment, it can be desalted water.

[0038] As an embodiment, the TOC of the fresh washing water is less than 1 mg / L. As another embodiment, the TOC may be less than 0.5 mg / L.

[0039] As an embodiment, the detergent is an anionic surfactant.

[0040] As an embodiment, the anionic surfactant is sodium dodecyl sulfate (SDS) and / or fatty alcohol polyoxyethylene ether sulfate (AES). As another embodiment, it can be sodium dodecyl sulfate (SDS).

[0041] As an embodiment, the concentration of the detergent in the mixed solution obtained by mixing the high-organic sodium chloride industrial salt, the first mother liquor and the detergent is 10 to 200 mg / L, and as another embodiment, it can be 50 to 80 mg / L.

[0042] As an embodiment, the TOC of the high organic sodium chloride industrial salt is ≥1000 mg / kg, and as another embodiment, it can be 1000 mg / kg.

[0043] As an embodiment, the mass ratio of the first mother liquor to the high-organic sodium chloride industrial salt is (1-2):1, and as another embodiment, it can be (1.2-1.5):1.

[0044] As an embodiment, the ultrasonic frequency of the first ultrasonic washing is 20 to 28 kHz, and as another embodiment, it can be 25 kHz.

[0045] As an embodiment, the first ultrasonic cleaning time is 15 to 60 minutes, and as another embodiment, it can be 30 to 40 minutes.

[0046] As an embodiment, the temperature of the first ultrasonic cleaning is 35-60°C, and as another embodiment, it can be 40-50°C.

[0047] As an embodiment, the first ultrasonic cleaning is performed under stirring conditions.

[0048] As an embodiment, the stirring rate is 20 to 80 rpm, and as another embodiment, it can be 30 to 60 rpm.

[0049] As an embodiment, the equipment used for the first solid-liquid separation is a screen centrifuge.

[0050] As an embodiment, the aperture of the sieve used for the first solid-liquid separation is 100-300 μm, and as another embodiment, it can be 150-200 μm.

[0051] As an embodiment, the first solid-liquid separation is centrifugal filtration.

[0052] As an embodiment, the centrifugal speed of the centrifugal filtration is 600 to 2500 rpm, and as another embodiment, it can be 1200 to 1500 rpm.

[0053] As an embodiment, the equipment used for the first ultrasonic washing is a first slurry distribution tank, an ultrasonic vibration device and a temperature control system; the first separated mother liquor is temporarily stored in the first mother liquor tank; when the first separated mother liquor temporarily stored in the first mother liquor tank reaches the overflow level, the first separated mother liquor is transported to the evaporation crystallization system for evaporation and crystallization; ultrasonic vibration plates are installed around the inner wall of the first slurry distribution tank; the material of the ultrasonic vibration plate is duplex steel or titanium; the ultrasonic vibration device is a side vibration type.

[0054] After obtaining the first separated crystals, the present invention mixes the first separated crystals with a second mother liquor, and sequentially performs a second ultrasonic washing and a second solid-liquid separation to obtain a second separated mother liquor and a second separated crystal, respectively.

[0055] As an embodiment, the second separated mother liquor is firstly recycled as the second mother liquor, and the remainder is recycled as the first mother liquor.

[0056] As an embodiment, before the second separation mother liquor is generated, the second mother liquor is fresh washing water.

[0057] As an embodiment, the mass ratio of the second mother liquor to the high-organic sodium chloride industrial salt is (1-2):1, and as another embodiment, it can be (1.2-1.5):1.

[0058] As an embodiment, the ultrasonic frequency of the second ultrasonic washing is 28 to 50 kHz, and as another embodiment, it can be 30 to 40 kHz; the ultrasonic frequencies of the first ultrasonic washing and the second ultrasonic washing are not the same.

[0059] As an embodiment, the second ultrasonic cleaning time is 15 to 60 minutes, and as another embodiment, it can be 30 to 40 minutes.

[0060] As an embodiment, the temperature of the second ultrasonic cleaning is 35-60°C, and as another embodiment, it can be 40-50°C.

[0061] As an embodiment, the second ultrasonic cleaning is performed under stirring conditions.

[0062] As an embodiment, the stirring rate is 20 to 80 rpm, and as another embodiment, it can be 30 to 60 rpm.

[0063] As an embodiment, the equipment used for the second solid-liquid separation is a screen centrifuge.

[0064] As an embodiment, the aperture of the sieve used for the second solid-liquid separation is 50 to 120 μm, and as another embodiment, it can be 60 to 100 μm.

[0065] As an embodiment, the second solid-liquid separation is centrifugal filtration.

[0066] As an embodiment, the centrifugal speed of the centrifugal filtration is 600 to 2500 rpm, and as another embodiment, it can be 1200 to 1500 rpm.

[0067] As an embodiment, the equipment used for the second ultrasonic washing is a second slurry mixing tank, an ultrasonic vibration device and a temperature control system; the second separated mother liquor is temporarily stored in the second mother liquor tank, and the remainder is temporarily stored in the first mother liquor tank; ultrasonic vibration plates are installed around the inner wall of the second slurry mixing tank; the material of the ultrasonic vibration plate is duplex steel or titanium; the ultrasonic vibration device is a side vibration type.

[0068] After obtaining the second separated crystals, the present invention mixes the second separated crystals with a third mother liquor, and sequentially performs a third ultrasonic washing and a third solid-liquid separation to obtain a third separated mother liquor and sodium chloride purified crystals, respectively.

[0069] As an embodiment, the third separated mother liquor is first reused as the third mother liquor, and the remainder is reused as the second mother liquor and the first mother liquor in sequence; the third mother liquor includes supplemented fresh washing water and the third separated mother liquor; before the third separated mother liquor is generated, the third mother liquor is entirely fresh washing water.

[0070] As an embodiment, the mass ratio of the third mother liquor to the high-organic sodium chloride industrial salt is (1-2):1, and as another embodiment, it can be (1.2-1.5):1.

[0071] As an embodiment, the mass ratio of the supplemented fresh washing water to the high-organic sodium chloride industrial salt is (0.5-1):1, and as another embodiment, it can be (0.6-0.9):1.

[0072] As an implementation manner, the ultrasonic frequency of the third ultrasonic washing is 50 to 80 kHz, and as another implementation manner it can be 60 to 70 kHz; the ultrasonic frequencies of the second ultrasonic washing and the third ultrasonic washing are not the same value.

[0073] As an embodiment, the third ultrasonic cleaning time is 15 to 60 minutes, and as another embodiment, it can be 30 to 40 minutes.

[0074] As an embodiment, the temperature of the third ultrasonic washing is 35-60°C, and as another embodiment, it can be 40-50°C.

[0075] As an embodiment, the third ultrasonic cleaning is performed under stirring conditions.

[0076] As an embodiment, the stirring rate is 20 to 80 rpm, and as another embodiment, it can be 30 to 60 rpm.

[0077] As an embodiment, the equipment used for the third solid-liquid separation is a screen centrifuge.

[0078] As an embodiment, the aperture of the sieve used for the third solid-liquid separation is 30 to 60 μm, and as another embodiment, it can be 40 to 50 μm.

[0079] As an embodiment, the third solid-liquid separation is centrifugal filtration.

[0080] As an embodiment, the centrifugal speed of the centrifugal filtration is 600 to 2500 rpm, and as another embodiment, it can be 1500 to 2000 rpm.

[0081] As an implementation mode, the equipment used for the third ultrasonic washing is a third slurry mixing tank, an ultrasonic vibration device and a temperature control system; the third separated mother liquor is temporarily stored in the third mother liquor tank, and the remainder is temporarily stored in the second mother liquor tank; ultrasonic vibration plates are installed around the inner wall of the third slurry mixing tank; the material of the ultrasonic vibration plate is duplex steel or titanium; the ultrasonic vibration device is a side vibration type.

[0082] As an embodiment, the TOC of the purified sodium chloride crystals is ≤200 mg / kg, and as another embodiment, it can be 122-182 mg / kg, and in specific embodiments, it is 122 mg / kg, 123 mg / kg, 138 mg / kg, 142 mg / kg, 150 mg / kg, 155 mg / kg, 158 mg / kg or 182 mg / kg.

[0083] As an embodiment, the yield of the purified sodium chloride crystals is ≥70%, and as another embodiment, it can be 70-79%, and in specific embodiments, it is 70%, 72%, 75%, 76%, 78% or 79%.

[0084] As an embodiment, the present invention uses the purified sodium chloride crystals for salt conversion or enters a deep treatment process; as an embodiment, the deep treatment process includes one or more of membrane separation, recrystallization and advanced oxidation, and as another embodiment, it can be membrane separation.

[0085] Figure 1 Flow chart of the method for purifying the crystal of high organic sodium chloride industrial salt in the embodiment of the present invention. Figure 1 As shown, the present invention mixes high-organic sodium chloride industrial salt and detergent and sequentially performs a first ultrasonic washing and a first solid-liquid separation, the obtained separated liquid is reused as a first mother liquor in the first ultrasonic washing, the obtained separated crystals are sequentially subjected to a second ultrasonic washing and a second solid-liquid separation, the obtained separated liquid is reused as a second mother liquor in the second and first ultrasonic washings, the excess separated liquid is evaporated and crystallized to obtain impure salt crystals, the obtained crystals are mixed with fresh washing water, and sequentially perform a third ultrasonic washing and a third solid-liquid separation, the obtained separated liquid is reused as a third mother liquor in the third, second, and first ultrasonic washings, and the obtained sodium chloride purified crystals are used for salt treatment.

[0086] The invention adopts a multi-stage countercurrent ultrasonic washing technology to purify the crystals of high-organic sodium chloride industrial salt, utilizes the cavitation effect of ultrasonic waves to promote the penetration of detergents, so that organic impurities are effectively stripped from salt crystals, can separate organic impurities in salt in an energy-saving and efficient manner, improve the washing effect, reduce the TOC content of the obtained sodium chloride purified crystals and improve the yield, so that the requirements for chlor-alkali salt are met, the refining cost is reduced, and the operating cost is reduced.

[0087] Furthermore, the present invention adopts a frequency-grading method for ultrasonic cleaning, first using low-frequency and high-energy-density ultrasonic waves for high-intensity auxiliary cleaning, aiming to break the state of polycrystalline agglomeration and then using high-frequency ultrasonic waves for refined cleaning to improve the cleaning effect.

[0088] Furthermore, the solid-liquid separation in the present invention adopts a graded centrifugal filtration design, mainly because as the salt crystal particle size gradually becomes smaller during the ultrasonic washing process, the accuracy of the separation filtration gradually decreases. The graded centrifugal method is used to best meet the balance between the crystal moisture content, the centrifugal salt leakage rate and the processing capacity, reduce the TOC content of the obtained sodium chloride purified crystals and improve the yield.

[0089] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0090] Example 1

[0091] (1) adding high-organic sodium chloride industrial salt (TOC content of 1000 mg / kg) to the first slurry preparation tank, and continuing to add the first mother liquor (initial fresh washing water, deionized water, TOC < 0.5 mg / L) and detergent (sodium dodecyl sulfate) with a mass of 1 times the mass of the high-organic sodium chloride industrial salt, and the concentration of the detergent in the obtained mixed solution is 50 mg / L; turning on the stirring and ultrasonic vibration device of the first slurry preparation tank, turning on the temperature control system, and performing the first ultrasonic washing for 30 minutes under the conditions of 25 kHz, 60 rpm, and 50° C., and then performing the first solid-liquid separation, that is, using a screen centrifuge for centrifugal filtration, the centrifugal speed is 800 rpm, and the aperture of the screen is 200 μm, to obtain a first separation mother liquor and a first separation crystal, respectively. The first separation mother liquor enters the first mother liquor tank and is reused as the first mother liquor, and the overflowing excess first separation mother liquor is transported to the evaporation crystallization system for evaporation crystallization;

[0092] (2) The first separated crystals are fed into a first slurry preparation tank, and a second mother liquor (initial fresh washing water, deionized water, TOC < 0.5 mg / L) with a mass of 1 times that of high-organic sodium chloride industrial salt is added. The stirring and ultrasonic vibration devices of the second slurry preparation tank are turned on, and the temperature control system is turned on. After a second ultrasonic washing for 30 minutes at 40 kHz, 60 rpm, and 50° C., a second solid-liquid separation is performed, i.e., centrifugal filtration is performed using a screen centrifuge, the centrifugal speed is 1200 rpm, and the aperture of the screen is 100 μm, to obtain a second separated mother liquor and a second separated crystal, respectively; the second separated mother liquor is temporarily stored in the second mother liquor tank, and the remainder is temporarily stored in the first mother liquor tank, and is reused as the second mother liquor and the first mother liquor in turn;

[0093] (3) The second separated crystals are sent into the first slurry preparation tank, and the third mother liquor (including the supplemented fresh washing water and the third separation mother liquor) with a mass of 1 times that of the high-organic sodium chloride industrial salt is added. Before the third separation mother liquor is produced, the third mother liquor is all fresh washing water, and the supplemented fresh washing water is 0.6 times the mass of the high-organic sodium chloride industrial salt, deionized water, TOC < 0.5 mg / L) is added. The stirring and ultrasonic vibration devices of the third slurry preparation tank are turned on, and the temperature control system is turned on. After the third ultrasonic washing is carried out at 60 kHz, 60 rpm, and 50°C for 30 minutes, the third solid-liquid separation is carried out, that is, centrifugal filtration is carried out using a screen centrifuge, the centrifugal speed is 1900 rpm, and the aperture of the screen is 50 μm, and the third separation mother liquor and sodium chloride purified crystals (TOC content is 155 mg / kg, and the yield is 78%) are obtained respectively; the third separation mother liquor is temporarily stored in the third mother liquor tank, and the remainder is temporarily stored in the second mother liquor tank, and is reused as the third mother liquor and the second mother liquor in turn.

[0094] Example 2

[0095] The difference from Example 1 is that the mass of the first mother liquor is 1.2 times the mass of the high-organic sodium chloride industrial salt, the mass of the second mother liquor is 1.2 times the mass of the high-organic sodium chloride industrial salt, the mass of the third mother liquor is 1.2 times the mass of the high-organic sodium chloride industrial salt (including the supplemented fresh washing water and the third separated mother liquor, before the third separated mother liquor is produced, the third mother liquor is all fresh washing water, the supplemented fresh washing water is 0.7 times the mass of the high-organic sodium chloride industrial salt, deionized water, TOC <0.5mg / L), the ultrasonic frequency of the first ultrasonic washing is 28k Hz, the ultrasonic frequency of the second ultrasonic washing is 40kHz, the ultrasonic frequency of the third ultrasonic washing is 60kHz, the mesh aperture of the first solid-liquid separation is 200μm, the mesh aperture of the second solid-liquid separation is 100μm, the mesh aperture of the third solid-liquid separation is 50μm, the temperature of the first ultrasonic washing, the second ultrasonic washing and the third ultrasonic washing are all 50°C, the stirring rate is 60rpm, the time is 40min, and the TOC content of the finally obtained sodium chloride purified crystals is 142mg / kg, and the yield is 75%.

[0096] Example 3

[0097] The difference from Example 1 is that the mass of the first mother liquor is 1.5 times the mass of the high-organic sodium chloride industrial salt, the mass of the second mother liquor is 1.5 times the mass of the high-organic sodium chloride industrial salt, the mass of the third mother liquor is 1.5 times the mass of the high-organic sodium chloride industrial salt (including the supplemented fresh washing water and the third separated mother liquor. Before the third separated mother liquor is produced, the third mother liquor is all fresh washing water, and the supplemented fresh washing water is 0.5 times the mass of the high-organic sodium chloride industrial salt, deionized water, TOC <0.5 mg / L), and the ultrasonic frequency of the first ultrasonic washing is 28 kHz, the ultrasonic frequency of the second ultrasonic washing is 40kHz, the ultrasonic frequency of the third ultrasonic washing is 80kHz, the aperture of the sieve used for the first solid-liquid separation is 100μm, the aperture of the sieve used for the second solid-liquid separation is 50μm, the aperture of the sieve used for the third solid-liquid separation is 30μm, the temperatures of the first ultrasonic washing, the second ultrasonic washing and the third ultrasonic washing are all 45°C, the stirring speed is all 50rpm, the time is all 60min, and the TOC content of the finally obtained sodium chloride purified crystals is 182mg / kg, and the yield is 79%.

[0098] Example 4

[0099] The difference from Example 1 is that the mass of the first mother liquor is twice the mass of the high-organic sodium chloride industrial salt, the mass of the second mother liquor is twice the mass of the high-organic sodium chloride industrial salt, the mass of the third mother liquor is twice the mass of the high-organic sodium chloride industrial salt (including the supplemented fresh washing water and the third separated mother liquor. Before the third separated mother liquor is produced, the third mother liquor is all fresh washing water, and the supplemented fresh washing water is 0.9 times the mass of the high-organic sodium chloride industrial salt, deionized water, TOC < 0.5 mg / L), the ultrasonic frequency of the first ultrasonic washing is 25 kHz, The ultrasonic frequency of the second ultrasonic washing is 28 kHz, the ultrasonic frequency of the third ultrasonic washing is 60 kHz, the mesh aperture of the first solid-liquid separation is 200 μm, the mesh aperture of the second solid-liquid separation is 100 μm, and the mesh aperture of the third solid-liquid separation is 50 μm. The temperatures of the first ultrasonic washing, the second ultrasonic washing and the third ultrasonic washing are all 55°C, the stirring rates are all 50 rpm, and the times are all 40 min. The TOC content of the finally obtained purified sodium chloride crystals is 122 mg / kg, and the yield is 70%.

[0100] Example 5

[0101] The difference from Example 1 is that the mass of the first mother liquor is twice the mass of the high-organic sodium chloride industrial salt, the mass of the second mother liquor is twice the mass of the high-organic sodium chloride industrial salt, the mass of the third mother liquor is twice the mass of the high-organic sodium chloride industrial salt (including the supplemented fresh washing water and the third separated mother liquor. Before the third separated mother liquor is produced, the third mother liquor is all fresh washing water, and the supplemented fresh washing water is 0.6 times the mass of the high-organic sodium chloride industrial salt, deionized water, TOC < 0.5 mg / L), the ultrasonic frequency of the first ultrasonic washing is 25 kHz, The ultrasonic frequency of the second ultrasonic washing is 28 kHz, the ultrasonic frequency of the third ultrasonic washing is 40 kHz, the mesh aperture of the first solid-liquid separation is 200 μm, the mesh aperture of the second solid-liquid separation is 100 μm, and the mesh aperture of the third solid-liquid separation is 50 μm. The temperatures of the first ultrasonic washing, the second ultrasonic washing, and the third ultrasonic washing are all 55° C., the stirring rates are all 50 rpm, and the times are all 40 min. The TOC content of the finally obtained purified sodium chloride crystals is 150 mg / kg, and the yield is 76%.

[0102] Example 6

[0103] The difference from Example 1 is that the mass of the first mother liquor is 1.5 times the mass of the high-organic sodium chloride industrial salt, the mass of the second mother liquor is 1.5 times the mass of the high-organic sodium chloride industrial salt, the mass of the third mother liquor is 1.5 times the mass of the high-organic sodium chloride industrial salt (including the supplemented fresh washing water and the third separated mother liquor, before the third separated mother liquor is produced, the third mother liquor is all fresh washing water, the supplemented fresh washing water is 0.8 times the mass of the high-organic sodium chloride industrial salt, deionized water, TOC <0.5mg / L), the ultrasonic frequency of the first ultrasonic washing is 20k Hz, the ultrasonic frequency of the second ultrasonic washing is 28kHz, the ultrasonic frequency of the third ultrasonic washing is 60kHz, the mesh aperture of the first solid-liquid separation is 200μm, the mesh aperture of the second solid-liquid separation is 100μm, the mesh aperture of the third solid-liquid separation is 50μm, the temperature of the first ultrasonic washing, the second ultrasonic washing and the third ultrasonic washing are all 50°C, the stirring rate is 50rpm, the time is 40min, and the TOC content of the finally obtained sodium chloride purified crystals is 123mg / kg, and the yield is 72%.

[0104] Example 7

[0105] The difference from Example 1 is that the mass of the first mother liquor is twice the mass of the high-organic sodium chloride industrial salt, the mass of the second mother liquor is twice the mass of the high-organic sodium chloride industrial salt, the mass of the third mother liquor is twice the mass of the high-organic sodium chloride industrial salt (including the supplemented fresh washing water and the third separated mother liquor. Before the third separated mother liquor is produced, the third mother liquor is all fresh washing water, and the supplemented fresh washing water is 0.6 times the mass of the high-organic sodium chloride industrial salt, deionized water, TOC < 0.5 mg / L), the ultrasonic frequency of the first ultrasonic washing is 25 kHz, The ultrasonic frequency of the second ultrasonic washing is 28 kHz, the ultrasonic frequency of the third ultrasonic washing is 50 kHz, the mesh aperture of the first solid-liquid separation is 200 μm, the mesh aperture of the second solid-liquid separation is 100 μm, and the mesh aperture of the third solid-liquid separation is 50 μm. The temperatures of the first ultrasonic washing, the second ultrasonic washing, and the third ultrasonic washing are all 55° C., the stirring rates are all 50 rpm, and the times are all 40 min. The TOC content of the finally obtained purified sodium chloride crystals is 158 mg / kg, and the yield is 78%.

[0106] Example 8

[0107] The difference from Example 1 is that the mass of the first mother liquor is 1.5 times the mass of the high-organic sodium chloride industrial salt, the mass of the second mother liquor is 1.5 times the mass of the high-organic sodium chloride industrial salt, the mass of the third mother liquor is 1.5 times the mass of the high-organic sodium chloride industrial salt (including the supplemented fresh washing water and the third separated mother liquor, before the third separated mother liquor is produced, the third mother liquor is all fresh washing water, the supplemented fresh washing water is 0.7 times the mass of the high-organic sodium chloride industrial salt, deionized water, TOC <0.5mg / L), the ultrasonic frequency of the first ultrasonic washing is 25k Hz, the ultrasonic frequency of the second ultrasonic washing is 40kHz, the ultrasonic frequency of the third ultrasonic washing is 60kHz, the mesh aperture of the first solid-liquid separation is 200μm, the mesh aperture of the second solid-liquid separation is 100μm, the mesh aperture of the third solid-liquid separation is 50μm, the temperatures of the first ultrasonic washing, the second ultrasonic washing and the third ultrasonic washing are all 60°C, the stirring rates are all 60rpm, the times are all 60min, and the TOC content of the finally obtained purified sodium chloride crystals is 138mg / kg, and the yield is 75%.

[0108] Comparative Example 1

[0109] High organic sodium chloride industrial salt with a TOC content of 1000 mg / kg was added with fresh washing water of 1 times its mass and stirred at 60 rpm for 60 min. It was filtered using a 200 μm pore size mesh centrifuge. The TOC content of the finally obtained crystalline salt was 403 mg / kg, and the yield was 68%.

[0110] Comparative Example 2

[0111] Add fresh washing water of 1 times the mass of high organic sodium chloride industrial salt with a TOC content of 1000 mg / kg, stir at 60 rpm for 60 min, and filter with a mesh centrifuge with a pore size of 200 μm. Add fresh washing water of 1 times the mass of high organic sodium chloride industrial salt to the obtained first separated crystals, stir at 60 rpm for 60 min, and filter with a mesh centrifuge with a pore size of 200 μm. Add fresh washing water of 0.6 times the mass of high organic sodium chloride industrial salt to the obtained second centrifugal crystals, stir at 60 rpm for 60 min, and filter with a mesh centrifuge with a pore size of 200 μm. The final crystalline salt has a TOC content of 335 mg / kg and a yield of 65%.

[0112] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for purifying a crystal of a high-organic sodium chloride industrial salt, characterized in that: The following steps are involved: Mixing high-organic sodium chloride industrial salt, a first mother liquor and a detergent, and sequentially performing a first ultrasonic washing and a first solid-liquid separation to obtain a first separation mother liquor and a first separation crystal, respectively; The first separated crystals and the second mother liquor are mixed, and a second ultrasonic washing and a second solid-liquid separation are sequentially performed to obtain a second separated mother liquor and a second separated crystal, respectively; The second separated crystals and the third mother liquor are mixed, and a third ultrasonic washing and a third solid-liquid separation are sequentially performed to obtain a third separated mother liquor and a sodium chloride purified crystal, respectively; The first separated mother liquor is reused as the first mother liquor; Before the first separation mother liquor is generated, the first mother liquor is fresh washing water; The second separated mother liquor is firstly recycled as the second mother liquor, and the remainder is recycled as the first mother liquor; Before the second separation mother liquor is generated, the second mother liquor is fresh washing water; The third separated mother liquor is first reused as the third mother liquor, and the remainder is reused as the second mother liquor and the first mother liquor in sequence; the third mother liquor includes supplemented fresh washing water and the third separated mother liquor; before the third separated mother liquor is generated, the third mother liquor is all fresh washing water.

2. The crystal purification method according to claim 1, characterized in that The ultrasonic frequency of the first ultrasonic washing is 20-28 kHz; the ultrasonic frequency of the second ultrasonic washing is 28-50 kHz; the ultrasonic frequency of the third ultrasonic washing is 50-80 kHz; the ultrasonic frequencies of the first ultrasonic washing and the second ultrasonic washing are not the same, and the ultrasonic frequencies of the second ultrasonic washing and the third ultrasonic washing are not the same.

3. The crystal purification method according to claim 1, characterized in that The detergent is an anionic surfactant.

4. The crystal purification method according to claim 1 or 3, characterized in that: The concentration of the detergent in the mixed solution obtained by mixing the high-organic sodium chloride industrial salt, the first mother liquor and the detergent is 10-200 mg / L.

5. The crystal purification method according to claim 1, characterized in that The aperture of the screen used for the first solid-liquid separation is 100-300 μm; the aperture of the screen used for the second solid-liquid separation is 50-120 μm; the aperture of the screen used for the third solid-liquid separation is 30-60 μm.

6. The crystal purification method according to claim 1, characterized in that: The mass ratio of the first mother liquor to the high-organic sodium chloride industrial salt is (1-2):1; the mass ratio of the second mother liquor to the high-organic sodium chloride industrial salt is (1-2):1; the mass ratio of the third mother liquor to the high-organic sodium chloride industrial salt is (1-2):1; the mass ratio of the supplemented fresh washing water to the high-organic sodium chloride industrial salt is (0.5-1):

1.

7. The crystal purification method according to claim 1, characterized in that The first ultrasonic cleaning, the second ultrasonic cleaning and the third ultrasonic cleaning are all carried out under stirring conditions; the stirring rate is independently 20 to 80 rpm.

8. The crystal purification method according to claim 1 or 7, characterized in that: The time of the first ultrasonic cleaning, the second ultrasonic cleaning and the third ultrasonic cleaning is independently 15 to 60 minutes.

9. The crystal purification method according to claim 1 or 7, characterized in that: The temperatures of the first ultrasonic cleaning, the second ultrasonic cleaning and the third ultrasonic cleaning are independently 35 to 60°C.

10. The crystal purification method according to claim 1, characterized in that: The fresh washing water is one or more of condensed water recycling water, soft water and demineralized water; the TOC of the fresh washing water is less than 1 mg / L.

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