Pyrolysis purification process for carnallite

Abstract

The invention discloses a carnallite pyrolysis purification process. The carnallite pyrolysis purification process comprises the following steps: S1, granulating; s2, drying; s3, performing pyrolysis; s4, screening; s5, oscillating; and S6, evaporative crystallization. The method has the advantages that the carnallite and the starch are mixed to prepare the pellets, then the pellets and the activated carbon particles are mixed and added into the pyrolysis device for pyrolysis, on one hand, the activated carbon particles belong to a wave-absorbing material, and the added activated carbon particles and the carnallite are jointly pyrolyzed, so that the heat and mass transfer effect can be improved, the carnallite heating time is shortened, and the microwave energy consumption is reduced; on the other hand, soluble starch is used as an adhesive for carnallite granulation, heat and raw materials can be fully mixed through pyrolysis after granulation, and the heating uniformity of the materials can be improved.

Description

Technical field:

[0001] The invention relates to the technical field of impure salt purification, in particular to an impure salt pyrolysis purification process. Background technology:

[0002] Trash salts are indirectly generated during the treatment of high-salt wastewater. These tramp salts have been oxidized and decomposed by organic matter in the pre-water treatment process, so the organic matter remaining in the tramp salts is mostly difficult to degrade and difficult to remove. The purification of tramp salts is the development trend of their treatment and disposal, and the removal of organic matter in tramp salts is the key to realizing resource utilization.

[0003] At present, one of the main technologies for purifying impure salts is microwave pyrolysis. When impure salts are subjected to high-temperature pyrolysis treatment under the action of microwaves, the removal rate of organic matter is high. However, the molten impure salts will adhere to the quartz glass or ceramic material tube of the pyrolysis equipment and are difficult to clean. Some components in the impure salts may even react chemically with the material tube, causing damage to the material tube. In addition, the microwave pyrolysis reaction device is easily affected by the accumulation of impure salts during the heating process, resulting in poor heat transfer performance. Microwave treatment will result in uneven heating, leading to local overheating that affects process stability, uneven carbonization of organic matter in the impure salts, and material compaction. In addition, the main components of impure salts are sodium chloride and sodium sulfate, which have weak microwave absorption capabilities, resulting in long heating time, slow rate, and high energy consumption in the microwave pyrolysis process. Summary of the invention:

[0004] The purpose of the present invention is to provide a process for pyrolysis and purification of impure salts.

[0005] The purpose of the present invention is implemented by the following technical scheme: a miscellaneous salt pyrolysis purification process, characterized in that it comprises the following steps:

[0006] S1 Granulation

[0007] Mix the miscellaneous salt and the soluble starch in a mass ratio of 0 to 2:98 and spray water to form wet pellets with a particle size of 1.5 cm to 3 cm;

[0008] S2 Drying

[0009] Drying the pellets obtained from S1 to obtain mixed salt pellets;

[0010] S3 Pyrolysis

[0011] The mixed salt pellets and activated carbon particles prepared from S2 are mixed in a mass ratio of 9:1 to 2.25 and then added to a pyrolysis device for pyrolysis to obtain a mixed material; the mixed salt can remove organic matter through pyrolysis, and the activated carbon particles are wave absorbing substances, which can shorten the heating time of the mixed salt and reduce energy consumption;

[0012] S4 Screening

[0013] The pyrolyzed mixed material is screened to separate the activated carbon particles to obtain purified pellets;

[0014] S5 shock

[0015] When the mixed salt pellets are pyrolyzed, the organic waste salt will gradually carbonize into stable pyrolytic carbon after pyrolysis, and the starch will be carbonized and converted into pyrolytic carbon; the purified pellets obtained by S4 are added with water and shaken, and then filtered to remove the pyrolytic carbon and obtain concentrated brine;

[0016] S6 Evaporation Crystallization

[0017] The concentrated brine obtained in S5 is evaporated and crystallized to obtain purified crystalline salt.

[0018] Furthermore, in S1, the moisture content of the wet pellets is 2% to 8%.

[0019] Furthermore, in S2, the drying time is 0.5h to 1.5h and the temperature is 80°C to 100°C.

[0020] Furthermore, in S3, the particle size of the activated carbon added is 0.5 cm.

[0021] Furthermore, in S3, the pyrolysis temperature is 350°C to 700°C, and the time is 1h to 3h.

[0022] Furthermore, in S5, the filtered pyrolytic carbon is filtered through a plate and frame filter press to obtain a pyrolytic carbon mud cake.

[0023] Advantages of the present invention: The present invention mixes the miscellaneous salt and starch to form pellets, and then mixes them with activated carbon particles and adds them to a pyrolysis device for pyrolysis. On the one hand, activated carbon particles are wave-absorbing materials. Adding activated carbon particles and pyrolyzing them together with the miscellaneous salt can improve the heat and mass transfer effect, shorten the heating time of the miscellaneous salt, and reduce microwave energy consumption; on the other hand, soluble starch is used as a binder for the granulation of the miscellaneous salt. After granulation, pyrolysis can fully mix the heat with the raw materials, improve the uniformity of the heating of the material, prevent the molten miscellaneous salt from adhering to the quartz glass or ceramic material tube of the pyrolysis equipment, and increase the service life of the material tube. In addition, after the pyrolysis of the mixed material is screened, the activated carbon particles therein can be recovered for recycling, and the remaining material can be dissolved in the water by adding water and shaking, and the waste salt can be separated from the pyrolysis carbon. The salt dissolved in the water can be recovered as sodium salt after being processed by the evaporation crystallization system. Description of the drawings:

[0024] Figure 1 It is a schematic diagram of the overall structure of this embodiment.

[0025] Miscellaneous salt storage tank 1, starch storage tank 2, mixing tank 3, granulator 4, activated carbon storage tank 5, dryer 6, oscillator 7, filter 8, evaporation crystallization system 9, plate and frame filter press 10, evaporation crystallizer 91, centrifuge 92, dryer 93, pyrolysis carbon silo 94, pyrolysis device 11, screening machine 12, buffer tank 13, water supply pipe 14. Specific implementation method:

[0026] In the description of the present invention, it should be noted that, if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, if the terms "first", "second", "third" appear, they are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0027] Example 1: Figure 1 As shown, a miscellaneous salt pyrolysis purification system includes a pyrolysis device 11, which also includes a miscellaneous salt storage tank 1, a starch storage tank 2, a stirring tank 3, a granulator 4, an activated carbon storage tank 5, a dryer 6, an oscillator 7, a filter 8 and an evaporation crystallization system 9, the outlets of the miscellaneous salt storage tank 1 and the starch storage tank 2 are connected to the inlet of the stirring tank 3, the outlet of the stirring tank 3 is connected to the inlet of the granulator 4, the outlet of the granulator 4 is connected to the inlet of the dryer 6, the outlet of the dryer 6 and the outlet of the activated carbon storage tank 5 are both connected to the inlet of the pyrolysis device 11; the outlet of the pyrolysis device 11 is connected to the inlet of the screening machine 12, the first outlet of the screening machine 12 is connected to the inlet of the activated carbon storage tank 5, the second outlet of the screening machine 12 is connected to the inlet of the buffer tank 13, the outlet of the buffer tank 13 and the water supply pipe 14 are both connected to the inlet of the oscillator 7, the outlet of the oscillator 7 is connected to the inlet of the filter 8, and the liquid phase outlet of the filter 8 is connected to the inlet of the evaporation crystallization system 9. The evaporation crystallization system 9 includes an evaporation crystallizer 91, a centrifuge 92, and a dryer 93 connected in sequence. The solid phase outlet of the filter 8 is connected to the inlet of the plate-frame filter press 10, and the outlet of the plate-frame filter press 10 is connected to the pyrolytic carbon silo 94.

[0028] Pyrolysis purification process:

[0029] S1 Granulation

[0030] The soluble starch in the starch storage tank 2 and the miscellaneous salt in the miscellaneous salt storage tank 1 are sent to the stirring tank 3 for mixing according to a mass ratio of 0 to 2:98, and then sent to the granulator 4, sprayed with water to form wet pellets with a particle size of 1.5 cm to 3 cm, and the moisture content of the wet pellets is 2% to 8%;

[0031] S2 Drying

[0032] The pellets obtained in S1 are sent to a dryer 6 for drying at a temperature of 80°C to 100°C for 0.5h to 1.5h to obtain mixed salt pellets with a moisture content of less than 2%;

[0033] S3 Pyrolysis

[0034] The mixed salt pellets obtained from S2 and the 0.5 cm activated carbon particles in the activated carbon storage tank 5 are mixed in a mass ratio of 9:1 to 2.25 and added to the pyrolysis device 11 for pyrolysis at a temperature of 350° C. to 700° C. for 1 h to 3 h to obtain a mixed material;

[0035] S4 Screening

[0036] The pyrolyzed mixed material is screened by a screener 12, and the activated carbon particles are separated and sent back to the activated carbon storage tank 5 for recycling to obtain purified pellets;

[0037] S5 shock

[0038] The purified pellets obtained in S4 are sent to the shaker 7 and water is added through the water supply pipe 14. After shaking, they are filtered through the filter 8 to remove the pyrolytic carbon and obtain concentrated brine. The removed pyrolytic carbon is filtered through the plate and frame filter press 10 to obtain a pyrolytic carbon mud cake, which is stored in the pyrolytic carbon silo 94 and can be reused as activated carbon after subsequent processing.

[0039] S6 Evaporation Crystallization

[0040] The concentrated brine obtained in S5 is evaporated and crystallized, and is sequentially passed through an evaporation crystallizer 91 for evaporation and crystallization, a centrifuge 92 for centrifugal separation, and a dryer 93 for drying to obtain purified crystalline salt.

[0041] Example 2: A process for pyrolysis purification of impure salts, comprising the following steps:

[0042] S1 Granulation

[0043] Soluble starch and miscellaneous salt are mixed in a mass ratio of 2:98 and sprayed with water to form wet pellets with a particle size of 1.5 cm and a moisture content of 8%;

[0044] S2 Drying

[0045] The pellets obtained by S1 are dried at a temperature of 100°C for 0.5 h to obtain mixed salt pellets;

[0046] S3 Pyrolysis

[0047] The mixed salt pellets prepared from S2 and the 0.5 cm activated carbon particles were mixed in a mass ratio of 9:2.25 and added into a pyrolysis device for pyrolysis at a temperature of 350°C for 3 hours to obtain a mixed material;

[0048] S4 Screening

[0049] The pyrolyzed mixed material is screened to separate the activated carbon particles to obtain purified pellets;

[0050] S5 shock

[0051] The purified pellets obtained in S4 are shaken with water and then filtered to remove the pyrolytic carbon to obtain concentrated brine; the filtered pyrolytic carbon is filtered through a plate and frame filter to obtain a pyrolytic carbon mud cake;

[0052] S6 Evaporation Crystallization

[0053] The concentrated brine obtained in S5 is evaporated and crystallized to obtain purified crystalline salt.

[0054] Embodiment 3: A process for pyrolysis purification of impurities comprising the following steps:

[0055] S1 Granulation

[0056] When the organic matter content in the salt is greater than 1500 mg / kg, the salt can be directly sprayed with water to form wet pellets with a particle size of 3 cm and a moisture content of 2%;

[0057] S2 Drying

[0058] The pellets prepared in S1 were dried at 80°C for 1.5 h to obtain mixed salt pellets;

[0059] S3 Pyrolysis

[0060] The mixed salt pellets prepared from S2 and the 0.5 cm activated carbon particles were mixed in a mass ratio of 9:1 and added into a pyrolysis device for pyrolysis at a temperature of 700°C for 1 h to obtain a mixed material;

[0061] S4 Screening

[0062] The pyrolyzed mixed material is screened to separate the activated carbon particles to obtain purified pellets;

[0063] S5 shock

[0064] The purified pellets obtained in S4 are shaken with water and then filtered to remove the pyrolytic carbon to obtain concentrated brine; the filtered pyrolytic carbon is filtered through a plate and frame filter to obtain a pyrolytic carbon mud cake;

[0065] S6 Evaporation Crystallization

[0066] The concentrated brine obtained in S5 is evaporated and crystallized to obtain purified crystalline salt.

[0067] Example 4: A process for pyrolysis purification of impurities comprising the following steps:

[0068] S1 Granulation

[0069] Soluble starch and miscellaneous salts were mixed in a mass ratio of 1:98 and sprayed with water to form wet pellets with a particle size of 2 cm and a moisture content of 5%.

[0070] S2 Drying

[0071] The pellets prepared by S1 were dried at 90°C for 1 h to obtain mixed salt pellets;

[0072] S3 Pyrolysis

[0073] The mixed salt pellets prepared from S2 and the 0.5 cm activated carbon particles were mixed in a mass ratio of 9:1.625 and added into a pyrolysis device for pyrolysis at a temperature of 600°C for 2 h to obtain a mixed material;

[0074] S4 Screening

[0075] The pyrolyzed mixed material is screened to separate the activated carbon particles to obtain purified pellets;

[0076] S5 shock

[0077] The purified pellets obtained in S4 are shaken with water and then filtered to remove the pyrolytic carbon to obtain concentrated brine; the filtered pyrolytic carbon is filtered through a plate and frame filter to obtain a pyrolytic carbon mud cake;

[0078] S6 Evaporation Crystallization

[0079] The concentrated brine obtained in S5 is evaporated and crystallized to obtain purified crystalline salt.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for pyrolysis and purification of miscellaneous salts, characterized in that: It includes the following steps: S1 Granulation Soluble starch and miscellaneous salt are mixed in a mass ratio of 0 to 2:98 and sprayed with water to form wet pellets with a particle size of 1.5 cm to 3 cm; S2 Drying Drying the pellets obtained from S1 to obtain mixed salt pellets; S3 Pyrolysis The mixed salt pellets and activated carbon particles prepared from S2 are mixed in a mass ratio of 9:1 to 2.25 and added into a pyrolysis device for pyrolysis to obtain a mixed material; S4 Screening The pyrolyzed mixed material is screened to separate the activated carbon particles to obtain purified pellets; S5 shock The purified pellets obtained in S4 are shaken with water and then filtered to remove the pyrolytic carbon to obtain a concentrated brine; S6 Evaporation Crystallization The concentrated brine obtained in S5 is evaporated and crystallized to obtain purified crystalline salt.

2. A miscellaneous salt pyrolysis purification process according to claim 1, characterized in that: In the above S1, the moisture content of the wet pellets is 2% to 8%.

3. A miscellaneous salt pyrolysis purification process according to claim 1, characterized in that: In S2, the drying time is 0.5h to 1.5h and the temperature is 80°C to 100°C.

4. A miscellaneous salt pyrolysis purification process according to claim 1, characterized in that: In the S3, the particle size of the activated carbon added is 0.5 cm.

5. A miscellaneous salt pyrolysis purification process according to claim 1, characterized in that: In S3, the pyrolysis temperature is 350°C to 700°C, and the time is 1h to 3h.

6. A miscellaneous salt pyrolysis purification process according to claim 1, characterized in that: In S5, the filtered pyrolytic carbon is filtered through a plate and frame filter press to obtain a pyrolytic carbon mud cake.

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