Sodium-potassium separation system for potassium-containing sodium carbonate solution

Abstract

The utility model discloses a sodium-potassium separation system for a potassium-containing sodium carbonate solution. The sodium-potassium separation system comprises an MVR (mechanical vapor recompression) evaporator, a first centrifugal machine, a refrigerator, a second centrifugal machine, a carbonizer and a third centrifugal machine, the method has the advantages that the carbonic acid type sodium sylvite does not need to be transformed into strong acid type sodium sylvite, sodium salt can be separated out through evaporation and concentration, then potassium bicarbonate can be obtained through freezing and carbonization, the separated sodium carbonate and potassium bicarbonate do not need to be crystallized repeatedly, and the separation cost is higher; the obtained sodium carbonate and potassium bicarbonate reach the industrial grade, and have obvious economic value.

Description

Technical field:

[0001] The utility model relates to a sodium-potassium separation system of a carbonate system, in particular to a sodium-potassium separation system of a potassium-containing sodium carbonate solution. Background technology:

[0002] Aluminum electrolytic plants produce five main types of solid waste: overhaul slag, cathode carbon blocks, anode carbon blocks, shell blocks, and electrolyte. Overhaul slag, in addition to its primary component, Na₃AlF₂, consists of refractory bricks. Cathode and anode carbon blocks, in addition to their primary components, Na₃AlF₂, consist of carbon powder. Shell blocks are primarily composed of Na₃AlF₂ and metallic aluminum. The electrolyte is primarily composed of Na₃AlF₂. Therefore, the solid waste produced by electrolytic plants contains a significant amount of cryolite, which has high utilization value. However, existing electrolytic plant solid waste recovery primarily focuses on lithium, without effectively recovering aluminum, fluorine, and sodium, resulting in significant resource waste. Our company has developed an alkaline calcium leaching process for recovering cryolite-containing solid waste from electrolytic plants. This process involves leaching the solid waste with alkaline calcium. Sodium, potassium, and lithium are leached into the leaching solution, while aluminum and fluorine remain in the leaching residue. The leaching solution and residue are then processed separately to recover their active components. Among them, the alkaline leaching solution is mainly separated into sodium carbonate mother liquor and crude lithium carbonate through carbonization reaction and MVR evaporation concentration. The sodium carbonate mother liquor continues to undergo MVR evaporation crystallization and is then centrifuged to obtain sodium carbonate monohydrate. The mother liquor separated by centrifugation contains potassium ions with a potassium-sodium ratio of 1:20, that is, when the sodium ion in the sodium carbonate solution is 100g / l, the potassium ion reaches 5g / l. This solution is already a carbonate system, and the potassium salt produced when sodium carbonate is recovered is only potassium carbonate or potassium bicarbonate; common sodium-potassium salt separation systems are all strongly acidic hydrochloric acid solutions, that is, strong acid is added to the sodium-potassium salt to form a chloride system, sulfate-hydrochloric acid system or nitrate system, etc., and then separated. The separated sodium and potassium salts are of low purity and need to be recrystallized, which is costly, complex, and inefficient. Utility model content:

[0003] The purpose of the utility model is to provide a sodium-potassium separation system for potassium-containing sodium carbonate solution.

[0004] The utility model is implemented by the following technical scheme: a sodium-potassium separation system for a potassium-containing sodium carbonate solution, which includes an MVR evaporator, a first centrifuge, a refrigerator, a second centrifuge, a carbonizer and a third centrifuge, wherein a feed pipe is connected to the inlet of the MVR evaporator, the outlet of the MVR evaporator is connected to the inlet of the first centrifuge, and the solid phase outlet of the first centrifuge is connected to a sodium carbonate discharge pipe; the liquid phase outlet of the first centrifuge is connected to the inlet of the refrigerator, the outlet of the refrigerator is connected to the inlet of the second centrifuge, the liquid phase outlet of the second centrifuge is connected to the inlet of the carbonizer, the outlet of the carbonizer is connected to the inlet of the third centrifuge, and the solid phase outlet of the third centrifuge is connected to a potassium bicarbonate discharge pipe.

[0005] Furthermore, the solid phase outlet of the second centrifuge is communicated with the inlet of the MVR evaporator.

[0006] Furthermore, a heating stirring tank is provided between the solid phase outlet of the second centrifuge and the inlet of the MVR evaporator, the solid phase outlet of the second centrifuge is communicated with the inlet of the heating stirring tank, and the outlet of the heating stirring tank is communicated with the inlet of the MVR evaporator.

[0007] Furthermore, the liquid phase outlet of the third centrifuge is connected to the inlet of the refrigerator.

[0008] Furthermore, a concentrator is provided between the liquid phase outlet of the third centrifuge and the inlet of the refrigerator, the liquid phase outlet of the third centrifuge is communicated with the inlet of the concentrator, and the outlet of the concentrator is communicated with the inlet of the refrigerator.

[0009] The utility model has the following advantages: carbonate-type sodium potassium salt does not need to be transformed into strong acid-type sodium potassium salt, and the sodium salt can be separated out through evaporation and concentration, and then potassium bicarbonate can be obtained through freezing and carbonization. The separated sodium carbonate and potassium bicarbonate do not need to be repeatedly crystallized, and the separation cost is more advantageous; the obtained sodium carbonate and potassium bicarbonate both reach industrial grade and have obvious economic value. Description of the drawings:

[0010] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0011] MVR evaporator 1, first centrifuge 2, refrigerator 3, second centrifuge 4, carbonizer 5, third centrifuge 6, potassium bicarbonate discharge pipe 7, heating and stirring tank 8, concentrator 9, sodium carbonate discharge pipe 10. Specific implementation method:

[0012] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like indicate positions or locations based on those shown in the accompanying drawings. These terms are intended solely to facilitate the description of this utility model and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used solely for descriptive purposes and should not be construed as indicating or implying relative importance.

[0013] like Figure 1 As shown, a sodium-potassium separation system for potassium-containing sodium carbonate solution includes an MVR evaporator 1, a first centrifuge 2, a refrigerator 3, a second centrifuge 4, a carbonizer 5 and a third centrifuge 6. The feed pipe is connected to the inlet of the MVR evaporator 1, the outlet of the MVR evaporator 1 is connected to the inlet of the first centrifuge 2, and the solid phase outlet of the first centrifuge 2 is connected to a sodium carbonate discharge pipe 10; the liquid phase outlet of the first centrifuge 2 is connected to the inlet of the refrigerator 3, the outlet of the refrigerator 3 is connected to the inlet of the second centrifuge 4, the liquid phase outlet of the second centrifuge 4 is connected to the inlet of the carbonizer 5, the solid phase outlet of the second centrifuge 4 is connected to the inlet of the MVR evaporator 1, and a heating stirring tank 8 is provided between the solid phase outlet of the second centrifuge 4 and the inlet of the MVR evaporator 1. The solid phase outlet of the second centrifuge 4 is connected to the inlet of the heating stirring tank 8, and the outlet of the heating stirring tank 8 is connected to the inlet of the MVR evaporator 1.

[0014] The outlet of the carbonizer 5 is connected to the inlet of the third centrifuge 6, and the solid phase outlet of the third centrifuge 6 is connected to a potassium bicarbonate discharge pipe 7. The liquid phase outlet of the third centrifuge 6 is connected to the inlet of the refrigerator 3. Specifically, a concentrator 9 is provided between the liquid phase outlet of the third centrifuge 6 and the inlet of the refrigerator 3. The liquid phase outlet of the third centrifuge 6 is connected to the inlet of the concentrator 9, and the outlet of the concentrator 9 is connected to the inlet of the refrigerator 3.

[0015] Separation process:

[0016] S1 Concentration

[0017] The potassium-containing sodium carbonate raw solution is sent to MVR evaporator 1 for concentration until sodium saturation and sodium carbonate monohydrate is crystallized to obtain a crystal slurry containing sodium carbonate monohydrate;

[0018] S2 primary solid-liquid separation

[0019] The crystal slurry obtained in S1 is sent to the first centrifuge 2 for solid-liquid separation to separate sodium carbonate monohydrate solid and high sodium and high potassium potassium carbonate solution;

[0020] S3 Freeze Crystallization

[0021] The high sodium and high potassium potassium carbonate solution separated by the first centrifuge 2 is fed into a freezer 3 for freezing until sodium carbonate decahydrate is crystallized to obtain a crystal slurry containing sodium carbonate decahydrate;

[0022] S4 Secondary solid-liquid separation

[0023] The crystal slurry obtained in S3 is sent to the second centrifuge 4 for secondary solid-liquid separation to separate the sodium carbonate decahydrate solid and the low sodium high potassium potassium carbonate solution;

[0024] S5 carbonization reaction

[0025] The solid phase separated by the second centrifuge 4 is sent to the heating stirring tank 8 for melting and then sent back to the MVR evaporator 1 for recycling treatment;

[0026] The low sodium and high potassium potassium carbonate solution obtained in S4 is fed into a carbonizer 5, and carbon dioxide is introduced at the same time to convert the potassium carbonate into potassium bicarbonate to obtain a crystal slurry of potassium bicarbonate crystals and a hydrogenation mother liquor containing sodium carbonate;

[0027] S6 three-stage solid-liquid separation

[0028] The crystal slurry obtained in S5 is sent to the third centrifuge 6 for solid-liquid separation to separate potassium bicarbonate solid and hydrogenation mother liquor containing sodium carbonate; the potassium bicarbonate solid is discharged from the potassium bicarbonate discharge pipe 7, and the liquid phase separated by the third centrifuge 6 is sent to the concentrator 9 for concentration and then returned to the refrigerator 3 for recycling treatment.

[0029] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sodium-potassium separation system for potassium-containing sodium carbonate solution, characterized in that: The invention comprises an MVR evaporator, a first centrifuge, a refrigerator, a second centrifuge, a carbonizer and a third centrifuge, wherein the feed pipe is connected to the inlet of the MVR evaporator, the outlet of the MVR evaporator is connected to the inlet of the first centrifuge, and the solid phase outlet of the first centrifuge is connected to a sodium carbonate discharge pipe; the liquid phase outlet of the first centrifuge is connected to the inlet of the refrigerator, the outlet of the refrigerator is connected to the inlet of the second centrifuge, the liquid phase outlet of the second centrifuge is connected to the inlet of the carbonizer, the outlet of the carbonizer is connected to the inlet of the third centrifuge, and the solid phase outlet of the third centrifuge is connected to a potassium bicarbonate discharge pipe.

2. The potassium-containing sodium carbonate solution sodium-potassium separation system according to claim 1, characterized in that: The solid phase outlet of the second centrifuge is communicated with the inlet of the MVR evaporator.

3. The potassium-containing sodium carbonate solution sodium-potassium separation system according to claim 2, characterized in that: A heating stirring tank is provided between the solid phase outlet of the second centrifuge and the inlet of the MVR evaporator. The solid phase outlet of the second centrifuge is communicated with the inlet of the heating stirring tank, and the outlet of the heating stirring tank is communicated with the inlet of the MVR evaporator.

4. The sodium-potassium separation system of potassium-containing sodium carbonate solution according to claim 1, characterized in that: The liquid phase outlet of the third centrifuge is communicated with the inlet of the refrigerator.

5. The sodium-potassium separation system of potassium-containing sodium carbonate solution according to claim 4, characterized in that: A concentrator is provided between the liquid phase outlet of the third centrifuge and the inlet of the refrigerator. The liquid phase outlet of the third centrifuge is communicated with the inlet of the concentrator, and the outlet of the concentrator is communicated with the inlet of the refrigerator.

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