Efficient treatment and recovery method of chlor-alkali salt mud

Abstract

The application discloses a kind of efficient treatment and recovery methods of chlor-alkali salt mud, belong to chlor-alkali salt mud resource technology field.A kind of efficient treatment and recovery methods of chlor-alkali salt mud, specifically includes four steps of gradient pretreatment, electrochemical synergistic oxidation treatment, dynamic electrode auxiliary filtration and resource utilization or safe disposal.By three-stage screening and air floatation reverse water washing, large particle impurities and water-soluble sodium chloride are effectively removed, an electrochemical reaction tank with titanium-based platinum or lead dioxide anode is used to synergistically oxidize and degrade organic impurities, then a dynamic electrode system with rotating anode structure is used to efficiently filter and dewater, and finally dry treatment and component diversion of salt mud are realized.The method has high desalination rate, complete impurity removal, significantly improved filtration efficiency, and the recovered product can be used for waste acid neutralization or building material filler, achieving waste resource utilization and recycling, suitable for chlor-alkali industry salt mud closed-loop treatment, with advantages of green environmental protection, low energy consumption, stable operation, etc.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chlor-alkali salt mud resource utilization, and more particularly to an efficient treatment and recovery method of chlor-alkali salt mud. BACKGROUND

[0002] A large amount of chlor-alkali salt mud is produced in the process of electrolysis and brine evaporation crystallization in the chlor-alkali industry, and the main components include sodium chloride, calcium carbonate, magnesium hydroxide, part of organic impurities and trace heavy metal ions. Due to the high salt content, complex impurity types and high water content in the salt mud, its disposal has been a key problem restricting the green production and clean discharge of enterprises. At present, the commonly used methods in industry include natural airing, incineration solidification or landfill disposal, but these methods have problems such as high energy consumption, low resource utilization rate, high risk of secondary pollution, etc., and it is difficult to meet the requirements of waste resource utilization and closed loop recycling.

[0003] In recent years, some studies have tried to extract salt by physical separation or agent conditioning, but there are problems such as unstable separation efficiency, high treatment cost, poor adaptability to subsequent resource utilization, etc. On the other hand, although clean treatment technologies such as electrochemical oxidation and membrane separation have high treatment capacity, they still face technical bottlenecks such as equipment blockage, dehydration difficulty, anode passivation, etc. when facing complex multiphase systems such as salt mud.

[0004] Therefore, there is an urgent need for a new chlor-alkali salt mud treatment process that has the capabilities of grading screening, efficient desalination, synergistic oxidation and resource utilization, in order to realize the deep reduction, harmless treatment and resource recovery of salt mud, and promote the green closed-loop development of the chlor-alkali industry. SUMMARY

[0005] The purpose of the present application is to provide an efficient treatment and recovery method of chlor-alkali salt mud, which has high desalination rate, complete impurity removal, significantly improved filtration efficiency, and the recovered product can be used for waste acid neutralization or building material filler, realizing waste resource utilization and recycling, suitable for salt mud closed-loop treatment in the chlor-alkali industry, with advantages of green environmental protection, low energy consumption, stable operation, etc.

[0006] An efficient treatment and recovery method of chlor-alkali salt mud, comprising the following steps:

[0007] S1, stepwise pretreatment: the chlor-alkali salt mud is sequentially subjected to stepwise pretreatment by grading screening and air flotation type reverse water washing device, to remove large particle impurities and preliminarily remove water-soluble sodium chloride and part of soluble impurities;

[0008] S2, electrochemical synergistic oxidation treatment: the washed salt mud slurry is introduced into an electrochemical reaction tank, and under the conditions of current density of 10-100 mA / cm2 and electrode spacing of 5-30 mm, electricity is passed to react, to degrade organic impurities by anodic oxidation and to strengthen the migration of soluble salts and trace metal ions in the salt mud;

[0009] S3, dynamic electrode auxiliary filtration: the salt slurry liquid after electrochemical treatment is introduced into a dynamic electrode auxiliary filtration system, the filtration efficiency is improved under the action of an electric field through a rotating electrode, meanwhile, membrane blockage and particle deposition are avoided, and efficient dewatering is realized;

[0010] S4, resource utilization or safe disposal: the treated dried salt slurry is divided into recyclable components and harmless components according to its composition, the recyclable components are used to prepare a waste acid neutralizer or a building material filler, and the remaining part is disposed according to environmental protection regulations.

[0011] Preferably, the grading screening adopts a three-stage vibrating screen + rotary screen, the screen holes are 3 mm, 1 mm and 0.3 mm, the vibration frequency is 20-40 Hz, the screen plate adopts an anti-corrosion PU material, and a spraying system is provided with a pressure of 0.2-0.5 MPa.

[0012] Preferably, the air flotation reverse water washing device comprises a gas-liquid mixing pump, a Venturi tube and a reverse flow separation chamber, the reverse flow mechanism can improve the sodium chloride removal rate to more than 80%, and the circulation frequency is 1-3 times.

[0013] Preferably, the anode of the electrochemical reaction tank is titanium-based coated with platinum, iridium tantalum or lead dioxide, and the cathode is graphite or stainless steel, and no additional auxiliary electrolyte is needed.

[0014] Preferably, the water used by the spraying system in the gradient pretreatment step and the air flotation reverse water washing device is recycled and regenerated, and is reused after being purified by membrane treatment or flocculation sedimentation.

[0015] Preferably, the anode of the dynamic electrode auxiliary filtration system adopts conductive ceramic or coated titanium, the cathode is a stainless steel wire mesh, the electrode spacing is 2-10 mm, the anode is provided with a spiral flow channel structure to optimize the discharge of the filtrate, the anode rotation speed is 60-300 rpm, and the flow velocity of the filtration module is 0.3-1.5 m / s.

[0016] Preferably, an intermittent polarity reversal or pulse power supply strategy is adopted in the electrochemical treatment process to improve the treatment efficiency and the anode life.

[0017] Preferably, the recyclable components in the salt slurry are dried and then treated by superheated steam carbonization, the carbonization temperature is controlled at 400-560℃, and the temperature is maintained for 20-40 minutes, which is used to prepare a pH self-adaptive neutralizer, and the product pH adjustment capacity is 6-11.

[0018] Preferably, the method is suitable for chlor-alkali enterprises electrolysis or evaporation crystallization section generated chlorinated salt slurry, the main components include sodium chloride, calcium carbonate, magnesium hydroxide, organic impurities and trace heavy metal ions.

[0019] Preferably, the washing liquid and concentrated liquid generated in the gradient pretreatment, electrochemical synergistic oxidation treatment and dynamic electrode assisted filtration steps are recycled to the chlor-alkali production system after membrane separation or evaporation crystallization treatment, forming a closed loop circulation system.

[0020] Compared with the prior art, the advantages of the present application are:

[0021] (1) Multi-dimensional gradient purification of salt mud is realized, and the impurity removal efficiency is improved

[0022] The present application effectively removes large particle impurities and soluble sodium chloride through the synergistic gradient pretreatment technology of grading screening and air flotation reverse water washing, so that the impurities in the salt mud are more thoroughly removed, providing a low load and homogeneous slurry basis for subsequent treatment, and the sodium chloride removal rate can be improved to more than 80%.

[0023] (2) Efficient oxidation of electrochemical auxiliary electrolyte, strengthening ion migration and degradation function

[0024] The electrochemical synergistic oxidation treatment process adopted can realize efficient degradation of organic impurities through titanium-based noble metal oxidation anode and other materials without the need for additional auxiliary electrolyte, promote the migration of trace metal ions from the solid-liquid interface to the liquid phase, and improve the metal recovery efficiency and environmental safety.

[0025] (3) Dynamic electrode structure filtration dewatering, inhibiting deposition and strengthening treatment flux

[0026] The dynamic electrode assisted filtration system composed of a rotating anode with a spiral flow channel structure and a high conductivity cathode significantly improves the dewatering speed under the combined action of the rotating electric field, reduces membrane pollution and particle accumulation, realizes continuous and stable operation, and has high filtrate flux and high dry mud solid content.

[0027] (4) Water resource recycling and diversified utilization of products, building a green closed loop system

[0028] All the spray liquid and reverse washing liquid can be recycled through membrane separation or flocculation sedimentation, reducing water consumption; meanwhile, the recoverable components in the dried salt mud after treatment can be further carbonized for pH neutralizer or building material filler, realizing maximum utilization of resources and reduction of solid waste.

[0029] (5) Strong process adaptability, compatible with multiple types of chlor-alkali waste, promoting industrial clean production

[0030] The method is suitable for typical chlorinated salt mud produced in the electrolysis, evaporation crystallization and other sections of the chlor-alkali industry, and is compatible with sodium, calcium, magnesium and other complex inorganic substances and trace organic impurities and heavy metals, and an integrated process path of "gradient separation-electrochemical synergy-high efficiency dewatering-resource utilization" is constructed, which has good popularization value and industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A process flow chart of a high-efficiency treatment and recovery method for chlor-alkali salt mud. DETAILED DESCRIPTION

[0032] To achieve the above object, the present application provides the following specific embodiments and examples: a high-efficiency treatment and recovery method for chlor-alkali salt mud, the steps of the high-efficiency treatment and recovery method for chlor-alkali salt mud being as follows:

[0033] S1, stepwise pretreatment: the chlor-alkali salt mud is sequentially subjected to stepwise pretreatment by grading screening and air flotation reverse water washing device, the grading screening adopts a three-section vibrating screen + rotary screen, the screen holes are 3 mm, 1 mm and 0.3 mm, the vibration frequency is 20-40 Hz, the screen plate adopts corrosion-resistant PU material, and a spraying system is provided, the pressure is 0.2-0.5 MPa, the air flotation reverse water washing device includes a gas-liquid mixing pump, a Venturi tube and a reverse flow separation chamber, the reverse flow mechanism can make the sodium chloride removal rate increase to more than 80%, the circulation number is 1-3 times, and the large-particle impurities are removed, and the water-soluble sodium chloride and part of the soluble impurities are preliminarily removed;

[0034] S2, electrochemical synergistic oxidation treatment: the washed salt mud slurry is introduced into an electrochemical reaction tank, the anode of the electrochemical reaction tank is titanium-based coated with platinum, iridium tantalum or lead dioxide, the cathode is graphite or stainless steel, and no additional auxiliary electrolyte is needed, and the electric current is turned on under the condition that the current density is 10-100 mA / cm 2 , the electrode spacing is 5-30 mm, the anodic oxidation is used to degrade the organic impurities, and the migration of the soluble salts and trace metal ions in the salt mud is strengthened;

[0035] S3, dynamic electrode assisted filtration: the salt mud slurry after the electrochemical treatment is introduced into a dynamic electrode assisted filtration system, the anode of the dynamic electrode assisted filtration system adopts conductive ceramic or coated titanium, the cathode is a stainless steel wire mesh, the electrode spacing is 2-10 mm, the anode is provided with a spiral flow channel structure to optimize the discharge of the filtrate, the anode rotation speed is 60-300 rpm, and the flow speed of the filtration module is 0.3-1.5 m / s, the filtration efficiency is improved under the action of the electric field by rotating the electrode, the membrane clogging and particle deposition are avoided, and efficient dewatering is realized;

[0036] S4, resource utilization or safe disposal: the treated dry salt mud is divided into recyclable components and harmless components according to the components, the recyclable components in the salt mud are dried and subjected to superheated steam carbonization treatment, the carbonization temperature is controlled at 400-560 DEG C, and the temperature is kept for 20-40 minutes, the pH self-adaptive neutralizing agent is prepared, the product pH adjustment capacity is 6-11, the harmless components are disposed according to the environmental protection regulations, and the building material filler is prepared;

[0037] The water used by the spraying system and the air floatation reverse water washing device in the gradient pretreatment step is recycled and regenerated for use, and is reused after being purified by membrane treatment or flocculation and sedimentation;

[0038] The intermittent polarity reversal or pulse power supply strategy is adopted in the electrochemical treatment process to improve the treatment efficiency and the anode life;

[0039] The method is suitable for chlor-alkali enterprise electrolysis or evaporation crystallization section generated chlorinated salt mud, the main components include sodium chloride, calcium carbonate, magnesium hydroxide, organic impurities and trace heavy metal ions;

[0040] The washing liquid and concentrated liquid generated in the gradient pretreatment, electrochemical synergistic oxidation treatment and dynamic electrode assisted filtration steps are recycled and reused for chlor-alkali production system after being treated by membrane separation or evaporation crystallization, forming a closed loop system.

[0041] Example 1: conventional chlor-alkali salt mud treatment example

[0042] S1, gradient pretreatment: the chlor-alkali salt mud is pretreated by gradient screening and air floatation reverse water washing device, the gradient screening adopts three-stage vibration screen + rotary screen, the screen hole is 3mm, 1mm, 0.3mm, the vibration frequency is 35Hz, the screen plate adopts corrosion-resistant PU material, with a spraying system, the pressure is 0.4MPa, the air floatation reverse water washing device includes gas-liquid mixing pump, venturi tube and reverse flow separation chamber, the circulation times is 2 times, the large particle impurities are removed and the water-soluble sodium chloride and part of the soluble impurities are preliminarily removed;

[0043] S2, electrochemical synergistic oxidation treatment: the washed salt mud slurry is introduced into the electrochemical reaction tank, the anode of the electrochemical reaction tank is iridium tantalum titanium mesh, the cathode is stainless steel, and no additional auxiliary electrolyte is needed, the power supply is under the condition of current density 50mA / cm 2 , electrode spacing 15mm, the anode oxidation is used to degrade organic impurities, and the migration of soluble salts and trace metal ions in the salt mud is strengthened;

[0044] S3, dynamic electrode assisted filtration: the salt mud slurry after electrochemical treatment is introduced into the dynamic electrode assisted filtration system, the anode of the dynamic electrode assisted filtration system adopts conductive ceramic, the cathode is stainless steel mesh, the electrode spacing is 5mm, the anode is provided with a spiral flow channel structure to optimize the discharge of filtrate, the anode rotation speed is 200rpm, the flow velocity of the filtration module is 1m / s, the rotation of the electrode under the action of electric field improves the filtration efficiency, at the same time avoids membrane clogging and particle deposition, and realizes high efficiency dehydration;

[0045] S4, resource utilization: the dried salt mud after treatment is treated by superheated steam carbonization, the carbonization temperature is controlled at 500℃, and the temperature is kept for 30 minutes, which is used for preparing pH self-adaptive neutralizer;

[0046] The water used by the spraying system and the air floatation reverse water washing device in the gradient pretreatment step is recycled and regenerated for use, and is reused after being treated and purified by a membrane;

[0047] The pulse power supply strategy is adopted in the electrochemical treatment process to improve the treatment efficiency and the anode life;

[0048] The method is suitable for chlor-alkali enterprise electrolysis or evaporation crystallization section generated chlorinated salt mud, the main components include sodium chloride, calcium carbonate, magnesium hydroxide, organic impurities and trace heavy metal ions;

[0049] The washing liquid and the concentrated liquid generated in the gradient pretreatment, electrochemical synergistic oxidation treatment and dynamic electrode auxiliary filtration steps are treated by evaporation crystallization and then reused in the chlor-alkali production system to form a closed loop system.

[0050] Example 2: Strengthening desalination + pulse electrolysis combined process

[0051] S1, Gradient pretreatment: The chlor-alkali salt mud is sequentially subjected to gradient pretreatment by grading screening and air floatation reverse water washing device, the grading screening adopts three-stage vibrating screen + rotary screen, the screen holes are 3mm, 1mm and 0.3mm, the vibration frequency is 40Hz, the screen plate adopts corrosion-resistant PU material, and the spraying system has a pressure of 0.5MPa, the air floatation reverse water washing device includes a gas-liquid mixing pump, a Venturi tube and a reverse flow separation chamber, the reverse flow mechanism can improve the sodium chloride removal rate to more than 80%, the cycle number is 3 times, and the large particle impurities are removed and the water-soluble sodium chloride and part of the soluble impurities are preliminarily removed;

[0052] S2, Electrochemical synergistic oxidation treatment: the washed salt mud slurry is introduced into the electrochemical reaction tank, the anode of the electrochemical reaction tank is iridium tantalum titanium mesh, the cathode is stainless steel, and no additional auxiliary electrolyte is needed, and the power is turned on under the condition that the current density is 80mA / cm 2 , the electrode spacing is 10mm, the anode oxidation is used to degrade the organic impurities, and the migration of the soluble salts and trace metal ions in the salt mud is strengthened;

[0053] S3, Dynamic electrode auxiliary filtration: the salt mud slurry treated by the electrochemical treatment is introduced into the dynamic electrode auxiliary filtration system, the anode of the dynamic electrode auxiliary filtration system adopts coated titanium, the cathode is stainless steel mesh, the electrode spacing is 5mm, the anode is provided with a spiral flow channel structure to optimize the discharge of the filtrate, the anode rotation speed is 300rpm, and the flow speed of the filtration module is 1.5m / s, the rotation of the electrode under the action of the electric field improves the filtration efficiency, avoids the membrane blockage and particle deposition, and realizes efficient dewatering;

[0054] S4, resource utilization or safe disposal: the treated dry salt sludge is divided into recyclable components and harmless components according to its composition, the recyclable components in the salt sludge are dried and treated by superheated steam carbonization, the carbonization temperature is controlled at 500 DEG C, and the temperature is kept for 30 minutes, which is used for preparing pH self-adaptive neutralizer, the harmless components are disposed according to environmental protection regulations, which is used for preparing building material filler;

[0055] The water used in the spraying system and the air floatation reverse water washing device in the step is recycled and regenerated after flocculation and sedimentation purification and then reused;

[0056] The intermittent polarity reversal and pulse power supply (on:off = 10s:5s) are used in the electrochemical treatment process to improve the treatment efficiency and the anode life;

[0057] The method is suitable for chlor-alkali enterprises electrolysis or evaporation crystallization section produced chlorinated salt sludge, the main components include sodium chloride, calcium carbonate, magnesium hydroxide, organic impurities and trace heavy metal ions;

[0058] The washing liquid and concentrated liquid generated in the steps of the step-by-step pretreatment, electrochemical synergistic oxidation treatment and dynamic electrode auxiliary filtration are recycled and used in the chlor-alkali production system after evaporation crystallization treatment, forming a closed loop system.

[0059] Example 3: salt sludge building material filler scheme

[0060] S1, step-by-step pretreatment: the chlor-alkali salt sludge is sequentially treated by step-by-step screening and air floatation reverse water washing device, the step-by-step screening adopts three-stage vibrating screen + rotary screen, the screen holes are 3mm, 1mm and 0.3mm, the vibration frequency is 20Hz, the screen plate adopts corrosion-resistant PU material, and the spraying system has a pressure of 0.3MPa, the air floatation reverse water washing device includes gas-liquid mixing pump, venturi tube and reverse flow separation chamber, the reverse flow mechanism can make the removal rate of sodium chloride reach more than 80%, the cycle number is 2 times, and the water-soluble sodium chloride and part of the soluble impurities are removed;

[0061] S2, electrochemical synergistic oxidation treatment: the washed salt sludge slurry is introduced into the electrochemical reaction tank, the anode of the electrochemical reaction tank is iridium tantalum titanium mesh, the cathode is stainless steel, and no additional auxiliary electrolyte is needed, the power supply is under the condition of current density 40mA / cm 2 , electrode spacing 25mm, the anode oxidation is used to degrade organic impurities, and the migration of soluble salts and trace metal ions in the salt sludge is strengthened;

[0062] S3, dynamic electrode auxiliary filtration: the salt slurry liquid after electrochemical treatment is introduced into the dynamic electrode auxiliary filtration system, the anode of the dynamic electrode auxiliary filtration system uses conductive ceramic, the cathode is stainless steel mesh, the electrode spacing is 6mm, the anode is provided with a spiral flow channel structure to optimize the discharge of filtrate, the anode rotates at 100rpm, the flow velocity of the filtration module is 0.5m / s, the rotation of the electrode under the action of the electric field improves the filtration efficiency, at the same time avoids membrane blockage and particle deposition, and realizes efficient dewatering;

[0063] S4, resource utilization or safe disposal: the treated dry salt mud is directly ground and refined to a particle size of <75um, and is mixed into a cement-based composite material to replace part of the mineral powder, the proportion is 15% (mass ratio);

[0064] The water used in the spray system and the air flotation reverse water washing device in the step of the cascade pretreatment is recycled and regenerated after being treated and purified by a membrane;

[0065] The pulse power supply strategy is used in the electrochemical treatment process to improve the treatment efficiency and the service life of the anode;

[0066] The method is suitable for chlor-alkali enterprises electrolysis or evaporation crystallization section produced chlorinated salt mud, the main components include sodium chloride, calcium carbonate, magnesium hydroxide, organic impurities and trace heavy metal ions;

[0067] The washing liquid and concentrated liquid generated in the steps of the cascade pretreatment, electrochemical synergistic oxidation treatment and dynamic electrode auxiliary filtration are recycled and used in the chlor-alkali production system after evaporation crystallization treatment, forming a closed loop system.

[0068] Example 4: Conductive ceramic electrode test

[0069] S1, cascade pretreatment: the chlor-alkali salt mud is sequentially treated by cascade screening and air flotation reverse water washing device, the cascade screening adopts three-stage vibration screen + rotary screen, the screen holes are 3mm, 1mm and 0.3mm, the vibration frequency is 35Hz, the screen plate is made of corrosion-resistant PU material, and the spray system is provided with a pressure of 0.4MPa, the air flotation reverse water washing device includes a gas-liquid mixing pump, a venturi tube and a reverse flow separation chamber, the reverse flow mechanism can make the removal rate of sodium chloride reach more than 80%, the cycle number is 1, and the large particle impurities are removed, and the water-soluble sodium chloride and part of the soluble impurities are preliminarily removed;

[0070] S2, electrochemical synergistic oxidation treatment: the washed salt mud slurry is introduced into the electrochemical reaction tank, the anode of the electrochemical reaction tank is a titanium-based platinum-coated ceramic rod, the cathode is stainless steel, and no additional auxiliary electrolyte is needed, the current density is 60mA / cm 2Under the condition of 20mm electrode spacing, the electric current is applied to the reaction, the anodic oxidation is used to degrade the organic impurities, and the migration of soluble salts and trace metal ions in the salt sludge is strengthened;

[0071] S3, dynamic electrode assisted filtration: the salt slurry after electrochemical treatment is introduced into the dynamic electrode assisted filtration system, the anode of the dynamic electrode assisted filtration system is coated titanium, the cathode is stainless steel mesh, the electrode spacing is 8mm, the anode is provided with a spiral flow channel structure to optimize the discharge of filtrate, the anode rotation speed is 250rpm, the flow velocity of the filtration module is 1.1m / s, the rotation electrode is used to improve the filtration efficiency under the action of electric field, and the membrane clogging and particle deposition are avoided, so that high efficiency dewatering is realized;

[0072] S4, resource utilization or safe disposal: the treated dry salt sludge is divided into recyclable components and harmless components according to its composition, the recyclable components in the salt sludge are dried and treated by superheated steam carbonization, the carbonization temperature is controlled at 480℃, and the temperature is kept for 25 minutes, which is used for preparing pH self-adaptive neutralizer, the harmless components are disposed according to environmental protection regulations, which is used for preparing building material filler;

[0073] The water used in the spray system and the air flotation reverse water washing device in the step of gradient pretreatment is recycled and regenerated after flocculation and sedimentation purification;

[0074] The intermittent polarity reversal or pulse power supply strategy is used in the electrochemical treatment process to improve the treatment efficiency and the anode life;

[0075] The method is suitable for chlor-alkali enterprises electrolysis or evaporation crystallization section produced chlorinated salt sludge, the main components include sodium chloride, calcium carbonate, magnesium hydroxide, organic impurities and trace heavy metal ions;

[0076] The washing liquid and concentrated liquid generated in the steps of gradient pretreatment, electrochemical synergistic oxidation treatment and dynamic electrode assisted filtration are recycled and used in the chlor-alkali production system after evaporation crystallization treatment, forming a closed loop circulation system.

[0077] Example 5: Small test device verifies closed loop circulation

[0078] S1, gradient pretreatment: the chlor-alkali salt sludge is sequentially treated by gradient screening and air flotation reverse water washing device, the gradient screening adopts three-stage vibration screen + rotary screen, the screen hole is 3mm, 1mm and 0.3mm, the vibration frequency is 40Hz, the screen plate is made of corrosion-resistant PU material, and the spray system is provided, the pressure is 0.5MPa, the air flotation reverse water washing device includes gas-liquid mixing pump, venturi tube and reverse flow separation chamber, the reverse flow mechanism can make the removal rate of sodium chloride reach more than 80%, the cycle number is 3 times, the large particle impurities are removed, and the water-soluble sodium chloride and part of the soluble impurities are preliminarily removed;

[0079] S2, electrochemical synergistic oxidation treatment: the water-washed salt slurry is introduced into an electrochemical reaction tank, the anode of the electrochemical reaction tank is a titanium-based platinum-coated ceramic rod, the cathode is stainless steel, and no additional auxiliary electrolyte is needed, and under the conditions of a current density of 100 mA / cm 2 , an electrode spacing of 30 mm, and power supply, the anodic oxidation is used to degrade organic impurities, and the migration of soluble salts and trace metal ions in the salt slurry is strengthened;

[0080] S3, dynamic electrode-assisted filtration: the electrochemically treated salt slurry is introduced into a dynamic electrode-assisted filtration system, the anode of the dynamic electrode-assisted filtration system is a conductive ceramic, the cathode is a stainless steel mesh, the electrode spacing is 10 mm, the anode is provided with a spiral flow channel structure to optimize the discharge of the filtrate, the anode rotates at a speed of 300 rpm, and the flow velocity of the filtration module is 1.5 m / s, so that the filtration efficiency is improved under the action of the electric field by rotating the electrode, and membrane clogging and particle deposition are avoided, and efficient dewatering is achieved;

[0081] S4, resource utilization or safe disposal: the treated dry salt slurry is divided into recyclable components and harmless components according to its composition, the recyclable components in the salt slurry are dried and treated by superheated steam carbonization at a carbonization temperature of 560°C for 40 minutes, and are used to prepare a pH self-adaptive neutralizing agent, and the harmless components are disposed of according to environmental protection regulations and are used to prepare building material fillers;

[0082] The water used in the spray system and the air flotation reverse washing device in the step of the cascade pretreatment is recycled and regenerated after being treated and purified by a membrane;

[0083] An intermittent polarity reversal or pulse power supply strategy is used in the electrochemical treatment process to improve the treatment efficiency and the anode life;

[0084] The method is suitable for chlor-alkali enterprise electrolysis or evaporation crystallization section produced chlorinated salt slurry, and the main components include sodium chloride, calcium carbonate, magnesium hydroxide, organic impurities and trace heavy metal ions;

[0085] The washing liquid and the concentrated liquid generated in the steps of the cascade pretreatment, the electrochemical synergistic oxidation treatment and the dynamic electrode-assisted filtration are treated by a membrane separation (nanofiltration + reverse osmosis) and are used in the chlor-alkali production system to form a closed loop circulation system.

[0086] Performance test

[0087] Sodium chloride removal rate

[0088] 50 g of dry salt slurry sample was mixed and divided into 5 parts, which were treated according to Examples 1-5, and the products were tested for sodium chloride removal rate, and the test equipment was Thermo iCAP 7000 inductively coupled plasma optical spectrum ICP-OES, and the method was to measure Na after dilution+ Concentration, test conditions and steps: sample before and after initial water washing to measure Na + Removal rate calculated by ratio, the following table is the test results:

[0089]

[0090] Dehydration rate of salt sludge (reduction of moisture content)

[0091] Take 50g of dried salt sludge sample, mix well and divide into 5 parts, and process according to Examples 1-5 respectively. Test the product for salt sludge dehydration rate. Test equipment: DHG-9140A electric heating air drying oven. Method: weight method. Test conditions and steps: dry at 105°C until constant weight. Compare the change in moisture content. The following table shows the test results:

[0092]

[0093] Removal rate of organic impurities (characterized by COD)

[0094] Take 50g of dried salt sludge sample, mix well and divide into 5 parts, and process according to Examples 1-5 respectively. Test the product. Test equipment: HACH DRB200+DR3900 rapid digestion spectrophotometer. Method: potassium dichromate oxidation method. Test conditions and steps: compare the concentration of COD before and after electrolysis. The following table shows the test results:

[0095]

[0096] Heavy metal migration efficiency (such as Cu 2+ , Zn 2+ )

[0097] Take 50g of dried salt sludge sample, mix well and divide into 5 parts, and process according to Examples 1-5 respectively. Test the product. Test equipment: AA240FS atomic absorption spectrometer. Method: measure the content of Cu and Zn in the filtrate. Test conditions and steps: measure the concentration change after acidification of the sample solution. The following table shows the test results:

[0098]

[0099] Performance evaluation of neutralizing agent / building material filler (pH adjustment ability, physical strength)

[0100] Take 50 g of dried salt mud sample, mix well and divide into 5 parts, and then process according to Examples 1-5 respectively, and test the product, the pH adjustment capacity test equipment is METTLER Toledo SevenExcellence pH meter, the method is acid-base titration, and the test conditions and steps are as follows: simulate adjustment of different pH acid, test dosage and pH response, the physical strength test equipment is YAW-300B cement compression tester, the method is: sample preparation by mixing cement mortar, 28d compression test, and the following table is the test results:

[0101]

Claims

1. A high-efficiency treatment and recovery method of chlor-alkali salt mud, characterized in that, It comprises the following steps: S1, step-by-step pretreatment: the chlor-alkali salt mud is sequentially subjected to step-by-step screening and air flotation reverse water washing device for step-by-step pretreatment, to remove large particle impurities and preliminarily remove water-soluble sodium chloride and part of soluble impurities; S2, electrochemical synergistic oxidation treatment: the water washed salt slurry is introduced into an electrochemical reaction tank, and under the condition that the current density is 10-100 mA / cm 2 , the electrode spacing is 5-30 mm, and the power is turned on to react, the anodic oxidation is used to degrade the organic impurities, and the migration of the soluble salts and trace metal ions in the salt slurry is strengthened. S3, dynamic electrode assisted filtration: the salt mud slurry after electrochemical treatment is introduced into a dynamic electrode assisted filtration system, the filtration efficiency is improved under the action of an electric field through rotating electrodes, meanwhile, membrane clogging and particle deposition are avoided, and efficient dewatering is realized; S4, resource utilization or safe disposal: the treated dry salt mud is divided into recyclable components and harmless components according to its composition, the recyclable components are used to prepare waste acid neutralizer or building material filler, and the rest is disposed according to environmental protection regulations; The air flotation reverse water washing device comprises a gas-liquid mixing pump, a Venturi tube and a reverse flow separation chamber, the reverse fluid mechanism can improve the sodium chloride removal rate to more than 80%, and the cycle number is 1-3 times; The dynamic electrode assisted filtration system uses conductive ceramic or coated titanium for the anode, stainless steel wire mesh for the cathode, the electrode spacing is 2-10 mm, the anode is provided with a spiral flow channel structure to optimize the discharge of filtrate, the anode rotating speed is 60-300 rpm, and the flow velocity of the filtration module is 0.3-1.5 m / s; The intermittent polarity reversal or pulse power supply strategy is adopted in the electrochemical treatment process to improve the treatment efficiency and anode life.

2. The method according to claim 1, characterized in that: The step-by-step screening adopts a three-stage vibrating screen + rotary screen, the screen holes are 3 mm, 1 mm and 0.3 mm, the vibration frequency is 20-40 Hz, the screen plate is made of corrosion-resistant PU material, and a spraying system is provided, and the pressure is 0.2-0.5 MPa.

3. The method according to claim 1, wherein the method is characterized by: The anode of the electrochemical reaction tank is titanium-based platinum-coated, iridium tantalum or lead dioxide, and the cathode is graphite or stainless steel, and no additional auxiliary electrolyte is needed.

4. The method according to claim 1, wherein the method is characterized by: The spraying system in the step-by-step pretreatment step and the water used by the air flotation reverse water washing device are recycled and regenerated, and are reused after membrane treatment or flocculation sedimentation purification.

5. The method of claim 1, wherein the method is characterized by: The recyclable components in the salt mud are dried and treated by superheated steam carbonization, the carbonization temperature is controlled at 400-560℃, and the temperature is maintained for 20-40 minutes, to prepare a pH self-adaptive neutralizer, and the product pH adjustment capacity is 6-11.

6. The method of claim 1, wherein the method is characterized by: The method is suitable for chlor-alkali enterprises electrolysis or evaporation crystallization section produced chlor-alkali salt mud, the main components include sodium chloride, calcium carbonate, magnesium hydroxide, organic impurities and trace heavy metal ions.

7. The method according to claim 1, wherein the method is characterized by: The washing liquid and concentrated liquid generated in the step-by-step pretreatment, electrochemical synergistic oxidation treatment and dynamic electrode assisted filtration steps are reused in the chlor-alkali production system after membrane separation or evaporation crystallization treatment, to form a closed loop circulation system.

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