Waste salt electrochemical treatment system

Abstract

The utility model discloses a waste salt electrochemical treatment system which comprises a salt dissolving tank, a regulating tank, an electric flocculation device, a sedimentation tank, an electrocatalytic oxidation device, an MVR (mechanical vapor recompression) evaporator, a centrifugal machine and a drying box which are sequentially connected in series, the salt dissolving tank is provided with a waste salt inlet and is further connected to the MVR evaporator, the regulating tank is further provided with an acid liquor and alkali liquor inlet, and the centrifugal machine is further connected to the drying box. Based on the advantages and characteristics of the electrochemical catalytic oxidation reaction, the high-efficiency degradation of organic matters in waste salt is realized, different current conditions can be changed according to the concentration of the organic matters, the waste salt can be recycled, and the treatment efficiency is improved. And long-period stable operation can be achieved, and good economic benefits and environmental protection benefits are achieved.

Description

Technical Field

[0001] The utility model discloses a waste salt electrochemical treatment system and a device, and relates to the field of resource utilization, treatment and disposal of industrial waste salt. Background Art

[0002] Industrial waste salt mainly comes from industrial waste salt containing organic matter and other toxic salt-containing waste liquids and solids generated in the production processes of chemical, pharmaceutical, agrochemical and coal chemical industries. The main salt production links include reaction salts produced by mother liquor (process wastewater), neutralization salts from acid-base chemical reactions, salting-out salts, and salt sludge produced by distillation residues.

[0003] At present, there are few technically and economically feasible disposal routes for waste salt. The commonly used disposal technologies for removing organic matter from waste salt are physical and chemical methods and high-temperature treatment methods. The physical and chemical methods are mainly divided into recrystallization, salt washing, extraction and advanced oxidation methods with the addition of oxidants. They have certain limitations in treating waste salt with complex components and high organic content. The treatment process is complicated and easily causes secondary pollution. The high-temperature treatment method is divided into high-temperature oxidation treatment, pyrolysis treatment and high-temperature melting treatment. A large amount of waste gas is generated during the treatment process of this method, which requires waste gas treatment, and there are problems such as melting, ringing and agglomeration, which cause equipment blockage and corrosion. At the same time, industrial waste salt is also an important chemical raw material. If the chemical by-product waste salt can be recycled and used as industrial raw material salt, it can not only eliminate its pollution to the environment, but also make full use of salt resources to realize the resource utilization and recycling of by-product salt. The premise of resource utilization is to remove the organic matter in the waste salt.

[0004] The high-salt organic wastewater produced after the dissolution of organic waste salt has the characteristic of high electrical conductivity. Electrochemical technology has unique advantages in the treatment of this type of wastewater. Electrocatalytic oxidation technology uses external electrodes to oxidize and degrade organic matter by utilizing the electron transfer between electrodes and organic matter or the hydroxyl radicals generated during the electrolysis process. Summary of the invention

[0005] Purpose of the invention: In view of the above-mentioned prior art, a waste salt electrochemical treatment system is proposed;

[0006] Technical solution: A waste salt electrochemical treatment system, including a salt dissolving tank, a regulating tank, an electric flocculation device, a sedimentation tank, an electrocatalytic oxidation device, an MVR evaporator, a centrifuge, and a drying box connected in series:

[0007] The salt dissolving pool is provided with a waste salt inlet, the salt dissolving pool is also connected to the MVR evaporator, the regulating tank is also provided with acid and alkali inlets, the sedimentation tank is provided with a slag discharge port, the centrifuge is also connected to the electrocatalytic oxidation device, and the drying box is provided with a recovered salt outlet.

[0008] Preferably, the anode of the electrocoagulation device is an aluminum electrode, the cathode is a graphite electrode, and the current density is 25-30 mA / cm 2 .

[0009] Preferably, the electrocatalytic oxidation device includes an electrolytic cell, which includes an electrolytic cell inlet 1, an electrode plate group 2, an electrode plate group partition plate 3, an electrolytic cell outlet 4, and a gas exhaust port 5; the electrode plate group 2 includes a positive electrode plate 6, a negative electrode plate 7, a positive plate connecting rod 8, a negative plate connecting rod 9, a sealing plate 10 and a handle 11, the electrolytic cell inlet 1 is connected to the upper salt solution of the sedimentation tank, the electrolytic cell outlet 4 is connected to the MVR evaporator, the gas exhaust port 5 is connected to the flue gas treatment system, the positive plate connecting rod 8 is connected to the positive electrode of the electrolytic power supply, the negative electrode connecting rod 9 is connected to the negative electrode of the electrolytic power supply, the sealing plate 10 is connected to the top of the electrolytic cell, and the handle 11 is connected to the top of the sealing plate 10.

[0010] Preferably, the electrolysis power supply adopts a variable frequency pulse power supply.

[0011] Preferably, the positive electrode plate 6 is a boron-doped diamond electrode, and the negative electrode plate 7 is a stainless steel electrode.

[0012] Preferably, 2-5 groups of electrode plate groups 2 are arranged in the electrolytic cell, and each group of electrode plate groups 2 is independently divided by electrode plate group partition plates 3; the electrolytic cell is cast as a whole.

[0013] Preferably, in the electrode plate group 2 , 15-20 positive electrode plates 6 and negative electrode plates 7 are alternately arranged, and there is one more negative electrode plate 7 than the positive electrode plate 6 .

[0014] Beneficial Effects: The utility model targets organic waste salt with TOC (total organic carbon) content ranging from 800 mg / L to 20,000 mg / L, adopts an electric flocculation device to remove SO42-, Mg2+, and Ca2+, and uses electrocatalytic oxidation technology to carry out oxidation-reduction treatment of organic pollutants in the waste salt. At the same time, it is combined with MVR evaporation technology, which has a wide range of applications, is easy to operate, and can realize automatic control, providing better technology and equipment for the resource utilization of waste salt. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a process flow of a waste salt electrochemical treatment system of the utility model;

[0016] Figure 2 A schematic diagram of an electrolytic cell corresponding to a waste salt electrochemical device of the utility model;

[0017] Figure 3 It is a schematic diagram of an electrode plate of an electrolytic cell in a waste salt electrochemical treatment device of the utility model;

[0018] In the figure: 1-electrolyzer sample inlet, 2-electrode plate group, 3-electrode plate group partition plate, 4-electrolyzer sample outlet, 5-electrolyzer gas discharge port, 6-positive electrode plate, 7-negative electrode plate, 8-positive plate connecting rod, 9-negative plate connecting rod, 10-sealing plate, 11-handle. DETAILED DESCRIPTION

[0019] The utility model is further explained below in conjunction with the accompanying drawings.

[0020] See also Figure 1 The utility model provides a waste salt electrochemical treatment system, the steps are as follows: the system includes the following steps: 1) adding the waste salt raw material into the salt dissolving pool to be configured into a saturated salt solution; 2) adjusting the pH value of the waste salt solution to 6-10 in the regulating pool; 3) the adjusted salt solution enters the electrocoagulation device for treatment; 4) when calcium, magnesium and other substances form insoluble matter in the electrocoagulation system, it enters the sedimentation tank for standing and discharges the sediment; 5) the upper salt solution enters the electrocatalytic oxidation device, and at the same time, the MVR evaporation centrifugal concentrated liquid is set to flow back to the electrocatalytic device for mixing and electrocatalytic oxidation treatment to remove organic pollutants and other pollutants. The parameter setting of the electrocatalytic oxidation device can be adjusted according to the different pollutant concentrations; 6) the upper clear liquid after the electrocatalytic oxidation treatment enters the MVR evaporator for evaporation and concentration, and the evaporated aqueous solution enters the salt dissolving pool for recycling; 7) the concentrated crude salt passes through the centrifugal-drying operation unit, and the salt is dried to obtain the recovered product salt;

[0021] The waste salt is waste salt or waste salt solution containing organic matter, with a TOC (total organic carbon) concentration of 800mg / L to 20000mg / L, and a total dissolved solid content (TDS) of 6000-10000mg / L after the salt dissolving pool is prepared; the electric flocculation device can better remove SO4 2- Mg 2+ , Ca 2+ Preferably, the anode is an aluminum electrode, the cathode is a graphite electrode, and the current density is 25-30 mA / cm 2 , reaction time 40-80min, electrocoagulation in situ produces Al 3+ As an aluminum source, the cathode provides OH - , forming ettringite precipitation; the electrocoagulation device, the calcium source is added in a distributed manner, that is, the electrocoagulation anode is first used to produce Al 3+ , react for 40-60 minutes, and then add Ca(OH)2 to form calcium sulfate precipitation for better effect. The electrocatalytic oxidation device sets the direction of the electrode plate in the tank parallel to the water flow direction, and according to the pollutant situation, 1-3 groups of electrolytic cells can be set in series for use, with a current density of 40-70mA / cm 2, staying in the electrochemical reaction tank for 40-120 min;

[0022] See also Figure 2 , Figure 3 The waste salt electrochemical treatment device comprises an electrolytic cell sample inlet (1), an electrode plate group (2), an electrode plate group partition plate (3), an electrolytic cell outlet (4), and a gas discharge port (5); the electrochemical device sample inlet (1) is connected to the upper salt solution after electrocoagulation, the electrolytic cell sample outlet (4) is connected to the rear end evaporation and salt separation process section, the gas discharge port (5) is connected to the flue gas treatment system, and the positive and negative electrode connecting rods are connected to the positive and negative electrodes of the electrolytic power supply. The electrolytic power supply adopts a variable frequency pulse power supply, which is more power-saving when adjusting the electrolytic intensity of the organic waste salt in the electrolytic cell. The electrode plate group (2) comprises a positive electrode plate (6), a negative electrode plate (7), a positive plate connecting rod (8), and a negative plate connecting rod (9); preferably, the positive electrode plate (6) is a boron-doped diamond (BDD) electrode, and the negative electrode plate (7) is a stainless steel electrode; preferably, three groups of electrode plate groups are arranged in the electrolytic cell, each group of electrode plate groups is independently divided by a partition, and 2-5 groups can be arranged accordingly according to demand; the electrolytic cell is cast as a whole to ensure the stability and waterproofness of the cell body; preferably, the anode plates and cathode plates in the electrode plate group (2) can be alternately arranged in 15-20 pieces, and the cathode plate has one more piece than the anode plate;

[0023] The above shows and describes the basic principles, main features and advantages of the utility model patent. The technicians in this industry should understand that the above implementation cases do not limit the utility model patent in any form, and all technical solutions obtained by equivalent replacement or equivalent transformation fall within the protection scope of the utility model patent.

[0024] Example 1: Take industrial waste salt from a pharmaceutical factory and determine the main components of the salt as shown in the following table:

[0025] Table 1 Main component data of waste salt from pharmaceutical factories (mg / g)

[0026]

[0027] After the waste salt is adjusted by dissolving salt, it enters the electrocoagulation device for treatment; the current density is set at 25mA / cm 2 The reaction time is 60 minutes. When a large amount of calcium, magnesium and other substances in the system are found to form insoluble matter after 50 minutes of reaction, the reaction is continued for 60 minutes to discharge the sediment; the upper salt solution of the electro-flocculation enters the electro-catalytic oxidation device, and the electro-catalytic oxidation current density is set to 45mA / cm 2, reaction time 40min, after sufficient reaction, the data of the supernatant salt solution are measured as shown in Table 2. The salt solution treated by the electrocatalytic device enters the MVR evaporator for evaporation and crystallization. After centrifugal separation, water washing and refining, and drying and crystallization unit treatment, the parameters of the finished salt are shown in Table 3.

[0028] Table 2 Data after electrocatalytic oxidation treatment

[0029]

[0030] Table 3 Finished salt data

[0031]

[0032] From the above results, it can be seen that the organic pollutants (TOC) in the waste salt have a good degradation effect in the electro-oxidation process, with a removal rate of more than 95%. The sodium chloride content, calcium and magnesium content, and sulfate content in the recovered finished salt also meet the reuse standards of industrial salt.

[0033] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A waste salt electrochemical treatment system, characterized in that: It includes salt dissolving tank, regulating tank, electric flocculation device, sedimentation tank, electrocatalytic oxidation device, MVR evaporator, centrifuge and drying box connected in series: The salt dissolving pool is provided with a waste salt inlet, the salt dissolving pool is also connected to the MVR evaporator, the regulating tank is also provided with acid and alkali inlets, the sedimentation tank is provided with a slag discharge port, the centrifuge is also connected to the electrocatalytic oxidation device, and the drying box is provided with a recovered salt outlet.

2. A waste salt electrochemical treatment system according to claim 1, characterized in that: The anode of the electrocoagulation device is an aluminum electrode, the cathode is a graphite electrode, and the current density is 25-30 mA / cm 2 .

3. A waste salt electrochemical treatment system according to claim 1, characterized in that: The electrocatalytic oxidation device comprises an electrolytic cell, wherein the electrolytic cell comprises an electrolytic cell sampling port (1), an electrode plate group (2), an electrode plate group partition plate (3), an electrolytic cell outlet (4), and a gas discharge port (5); the electrode plate group (2) comprises a positive electrode plate (6), a negative electrode plate (7), a positive plate connecting rod (8), a negative plate connecting rod (9), a sealing plate (10), and a handle (11); the electrolytic cell sampling port (1) is connected to the upper salt solution of the sedimentation tank; the electrolytic cell outlet (4) is connected to the MVR evaporator; the gas discharge port (5) is connected to the flue gas treatment system; the positive plate connecting rod (8) is connected to the positive electrode of the electrolytic power supply; the negative plate connecting rod (9) is connected to the negative electrode of the electrolytic power supply; the sealing plate (10) is connected to the top of the electrolytic cell; and the handle (11) is connected to the top of the sealing plate (10).

4. A waste salt electrochemical treatment system according to claim 3, characterized in that: The electrolysis power supply adopts a variable frequency pulse power supply.

5. A waste salt electrochemical treatment system according to claim 3, characterized in that: The electrolytic cell is provided with 2-5 groups of electrode plate groups (2), each group of electrode plate groups (2) is independently divided by an electrode plate group partition plate (3); the electrolytic cell is cast in one piece.

6. A waste salt electrochemical treatment system according to claim 3, characterized in that: In the electrode plate group (2), 15 to 20 positive electrode plates (6) and negative electrode plates (7) are alternately arranged, and the number of negative electrode plates (7) is one more than that of positive electrode plates (6).

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