Refining system of lithium carbonate containing aluminum and fluorine

Abstract

The refining system comprises a dissolving tank, a dissolved acid storage tank, an alkali liquor storage tank, a first washing and filtering machine, a first resin exchange column, a pure sodium carbonate feeding pipe, a lithium carbonate precipitation tank, a second washing and filtering machine, a pulping tank, a centrifugal separator and a drying machine. The method has the advantages that aluminum in the aluminum-fluorine-containing coarse lithium carbonate is reasonably utilized, after the coarse lithium carbonate is dissolved in the dissolving tank, part of fluorine is precipitated into cryolite, then the alkaline solution is added, excessive aluminum generates active aluminum hydroxide which has a very strong adsorption effect on fluorine, the fluorine removal effect is achieved, and aluminum-fluorine residues are separated out by washing and filtering through the first washing and filtering machine. And mixing the low-sodium pure lithium solution from which the aluminum and fluorine residues are separated with pure sodium carbonate in a lithium carbonate precipitation tank to prepare lithium carbonate slurry, and sequentially filtering, washing, centrifugally dewatering and drying the lithium carbonate slurry to obtain a high-purity lithium carbonate product.

Description

Technical Field:

[0001] The utility model relates to the technical field of lithium carbonate refining, and particularly to a refining system for aluminum-containing lithium hexafluoroaluminate. Background Art:

[0002] The solid wastes produced by electrolytic aluminum plants mainly include overhaul slag, cathode carbon blocks, anode carbon blocks, crust blocks, and electrolytes. Among them, the main components of overhaul slag are Na 3 AlF 6 In addition to refractory bricks, the main components of cathode carbon blocks and anode carbon blocks are Na 3 AlF 6 In addition to carbon powder, the main component of crust blocks is Na 3 AlF 6 And metallic aluminum, and the main component of electrolytes is Na 3 AlF 6 . It can be seen that the solid wastes produced by electrolytic plants contain a large amount of cryolite and have high utilization value. At present, our company has developed a process for alkaline calcium leaching and recycling of cryolite-containing solid wastes in electrolytic plants. The solid wastes are mainly subjected to alkaline leaching with alkaline calcium, and sodium, potassium, and lithium are leached into the alkaline leaching solution, while aluminum and fluorine mainly remain in the alkaline leaching residue, and a small amount of aluminum and fluorine remain in the alkaline leaching solution. Then, the alkaline leaching solution and the alkaline leaching residue are respectively treated to recover the effective components therein. Among them, the alkaline leaching solution is mainly separated into sodium carbonate mother liquor and crude lithium carbonate through carbonization reaction and MVR evaporation and concentration, and aluminum and fluorine remain in the crude lithium carbonate.

[0003] At present, the common method for refining crude lithium carbonate is the hydrogenation method, that is, the crude lithium carbonate is first made into a low-concentration slurry, then hydrogenated with carbon dioxide in a carbonization tower, and the lithium bicarbonate solution is obtained by low-temperature filtration. Then, the lithium bicarbonate solution is heated to remove carbon to obtain lithium carbonate. This method can produce battery-grade lithium carbonate. If the above-mentioned aluminum- and fluorine-containing crude lithium carbonate is refined by the hydrogenation method, a small amount of aluminum enters the lithium bicarbonate solution during the hydrogenation process, and the solubility of fluorine is 0.01 mol / l. After heating and decomposition, sodium carbonate has serious problems of excessive aluminum and fluorine and cannot produce qualified lithium carbonate. Content of the Utility Model:

[0004] The purpose of the utility model is to provide a refining system for aluminum-containing lithium hexafluoroaluminate.

[0005] The utility model is implemented by the following technical solutions: A refining system for lithium aluminum fluorocarbonate, characterized in that it includes a dissolution tank, a dissolved acid storage tank, an alkali solution storage tank, a first washing and filtering machine, a first resin exchange column, a pure sodium carbonate feed pipe, a lithium carbonate precipitation tank, a second washing and filtering machine, a pulping tank, a centrifugal separator, and a dryer. At the top of the dissolution tank, there are a crude lithium carbonate feeding port, an acid adding port, and an alkali adding port; the outlet of the dissolution tank is connected to the inlet of the first washing and filtering machine, and the filtrate outlet of the first washing and filtering machine is connected to the inlet of the first resin exchange column; the outlet of the first resin exchange column and the pure sodium carbonate feed pipe are both connected to the inlet of the lithium carbonate precipitation tank, the outlet of the lithium carbonate precipitation tank is connected to the inlet of the second washing and filtering machine, the slag discharge port of the second washing and filtering machine is connected to the inlet of the pulping tank, the outlet of the pulping tank is connected to the inlet of the centrifugal separator, the solid phase outlet of the centrifugal separator is connected to the inlet of the dryer, and the outlet of the dryer is connected to a lithium carbonate product discharge pipe.

[0006] Further, the washing water outlet of the first washing and filtering machine is connected to the inlet of the dissolution tank.

[0007] Further, the filtrate outlet of the second washing and filtering machine is connected to the inlet of a carbon dioxide discharge tank, and an acid solution feed pipe is connected to the side of the carbon dioxide discharge tank; the outlet of the carbon dioxide discharge tank is connected to the inlet of an MVR evaporation crystallizer, and a sodium salt product discharge pipe is connected to the crystal phase outlet of the MVR evaporation crystallizer.

[0008] Further, the mother liquor outlet of the MVR evaporation crystallizer is connected to the inlet of the dissolution tank.

[0009] Further, it further includes a sodium carbonate solution preparation tank, a filter, and a second resin exchange column connected in sequence, and the outlet of the second resin exchange column is connected to the inlet end of the pure sodium carbonate feed pipe.

[0010] Further, the washing water outlets of the second washing and filtering machine and the centrifugal separator are both connected to the inlet of the sodium carbonate solution preparation tank.

[0011] Advantages of the utility model: The aluminum in the crude lithium aluminum fluoride carbonate is reasonably utilized. After dissolving the crude lithium carbonate in the dissolution tank, part of the fluorine is precipitated as cryolite, and then an alkali solution is added to make the excessive aluminum generate active aluminum hydroxide, which has a strong adsorption effect on fluorine, achieving the effect of removing fluorine. After washing and filtering by the first washing and filtering machine, the aluminum fluoride slag is separated, and the aluminum fluoride slag and the small amount of lithium carried therein are recovered without lithium loss, improving the recovery rate of the effective components. The low-sodium pure lithium solution separated from the aluminum fluoride slag and pure sodium carbonate are mixed in the lithium carbonate precipitation tank to prepare a lithium carbonate slurry, and then the lithium carbonate slurry is filtered and washed, centrifugally dehydrated, and dried in sequence to obtain a high-purity lithium carbonate product. Description of the Drawings:

[0012] Figure 1 It is a schematic diagram of the overall structure of this embodiment.

[0013] Dissolution tank 1, crude lithium carbonate feeding port 101, acid adding port 2, alkali adding port 3, first washing and filtering machine 4, first resin exchange column 5, pure sodium carbonate feeding pipe 6, lithium carbonate precipitation tank 7, second washing and filtering machine 8, pulping tank 9, centrifugal separator 10, dryer 11, lithium carbonate product discharging pipe 12, carbon dioxide discharging tank 13, acid solution feeding pipe 14, MVR evaporation crystallizer 15, sodium salt product discharging pipe 16, sodium carbonate solution preparation tank 17, filter 18, second resin exchange column 19. Detailed Embodiments:

[0014] In the description of the present invention, it should be noted that when terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the present invention. In addition, when terms such as "first", "second", "third" appear, they are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0015] As Figure 1 shown, a refining system for lithium aluminum fluorocarbonate includes a dissolution tank 1, an acid adding port 3, an alkali adding port 3, a first washing and filtering machine 4, a first resin exchange column 5, a pure sodium carbonate feeding pipe 6, a lithium carbonate precipitation tank 7, a second washing and filtering machine 8, a pulping tank 9, a centrifugal separator 10, and a dryer 11.

[0016] At the upper part of the dissolution tank 1, a crude lithium carbonate feeding port 101, an acid adding port 2, and an alkali adding port 3 are connected;

[0017] The outlet of the dissolution tank 1 is connected to the inlet of the first washing and filtering machine 4, and the filtrate outlet of the first washing and filtering machine 4 is connected to the inlet of the first resin exchange column 5;

[0018] The outlet of the first resin exchange column 5 and the pure sodium carbonate feeding pipe 6 are both connected to the inlet of the lithium carbonate precipitation tank 7. The outlet of the lithium carbonate precipitation tank 7 is connected to the inlet of the second washing and filtering machine 8. The slag discharging port of the second washing and filtering machine 8 is connected to the inlet of the pulping tank 9. The outlet of the pulping tank 9 is connected to the inlet of the centrifugal separator 10. The solid phase outlet of the centrifugal separator 10 is connected to the inlet of the dryer 11. The outlet of the dryer 11 is connected to a lithium carbonate product discharging pipe 12.

[0019] The washing water outlet of the first washing and filtering machine 4 is communicated with the inlet of the dissolving tank 1.

[0020] The filtrate outlet of the second washing and filtering machine 8 is communicated with the inlet of the carbon dioxide discharging tank 13, and an acid solution feeding pipe 14 is communicated with the side of the carbon dioxide discharging tank 13; the outlet of the carbon dioxide discharging tank 13 is communicated with the inlet of the MVR evaporation crystallizer 15, and a sodium salt product discharging pipe 16 is communicated with the crystal phase outlet of the MVR evaporation crystallizer 15.

[0021] The mother liquor outlet of the MVR evaporation crystallizer 15 is communicated with the inlet of the dissolving tank 1.

[0022] It further includes a sodium carbonate solution preparation tank 17, a filtering machine 18 and a second resin exchange column 19 which are connected in sequence, and the outlet of the second resin exchange column 19 is communicated with the inlet end of the pure sodium carbonate feeding pipe 6.

[0023] The washing water outlets of the second washing and filtering machine 8 and the centrifugal separator 10 are both communicated with the inlet of the sodium carbonate solution preparation tank 17.

[0024] Working principle:

[0025] The crude lithium carbonate containing aluminum and fluorine is put into the dissolving tank 1 from the crude lithium carbonate feeding port 101, and then hydrochloric acid is added into the dissolving tank 1 from the acid adding port 3 to dissolve and obtain a crude lithium chloride solution, and its pH is controlled at 1-3, wherein part of aluminum and fluorine are in the form of Na 3 AlF 6 precipitate (AlCl 3 +6NaF = Na 3 AlF 6 ↓ + 3NaCl);

[0026] After that, sodium hydroxide solution is added into the dissolving tank 1 from the alkali adding port 3 to adjust the pH to 5-8, and the remaining aluminum exists in the form of flocculent Al(OH) 3 and has an adsorption effect on fluoride ions;

[0027] Then, the slurry in the dissolving tank 1 is sent into the first washing and filtering machine 4 for washing and filtering to separate out solid-phase aluminum fluoride slag (which can be sent back to the alkali leaching process for cyclic treatment), impurity-containing lithium salt filtrate and washing water. The washing water separated by the first washing and filtering machine 4 can be sent back to the dissolving tank 1 for cyclic treatment, and the separated impurity-containing lithium salt filtrate is sent into the first resin exchange column 5 to remove soluble divalent and trivalent metals in the lithium solution to obtain a low-sodium pure lithium solution.

[0028] The low-sodium pure lithium solution discharged from the first resin exchange column 5 and the pure sodium carbonate fed by the pure sodium carbonate feed pipe 6 are sent into the lithium carbonate precipitation tank 7 together to be mixed to prepare a lithium carbonate slurry. Then, the lithium carbonate slurry is successively sent into a second washing and filtering machine, a centrifugal separator, and a dryer for filtration and washing, centrifugal dehydration, and drying to obtain a lithium carbonate product, which is discharged from the system through the lithium carbonate product discharge pipe 12. Among them, the pure sodium carbonate supplied by the pure sodium carbonate feed pipe 6 is made from high-quality industrial sodium carbonate. Specifically, it is put into the sodium carbonate solution preparation tank 17 and then filtered and purified through a filter 18 and a second resin exchange column 19 to obtain pure sodium carbonate. The washing water discharged from the second washing and filtering machine 8 and the washing water discharged from the centrifugal separator 10 are sent back to the sodium carbonate solution preparation tank 17 for cyclic treatment.

[0029] The filtrate discharged from the second washing and filtering machine 8 is mainly a sodium salt solution. First, it is sent into a carbon dioxide discharge tank 13, where hydrochloric acid, sulfuric acid, or nitric acid is added to react with the excess sodium carbonate in the solution to discharge carbon dioxide. The solution discharged from the carbon dioxide discharge tank 13 is then sent into an MVR evaporation crystallizer 15 for evaporation crystallization to obtain the corresponding sodium chloride, sodium sulfate, or sodium nitrate salt; the mother liquor discharged from the MVR evaporation crystallizer 15 contains a high concentration of lithium and is sent back to the dissolution tank 1 for cyclic treatment.

[0030] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A refining system containing lithium aluminum fluorocarbonate, characterized in that: It includes a dissolving tank, a dissolving acid storage tank, an alkali solution storage tank, a first washing filter, a first resin exchange column, a pure sodium carbonate feeding pipe, a lithium carbonate precipitation tank, a second washing filter, a pulping tank, a centrifugal separator, and a dryer. A crude lithium carbonate feeding port, an acid adding port, and an alkali adding port are arranged on the top of the dissolving tank. The outlet of the dissolving tank is connected to the inlet of the first washing filter, and the filtrate outlet of the first washing filter is connected to the inlet of the first resin exchange column; the outlet of the first resin exchange column and the pure sodium carbonate feeding pipe are both connected to the inlet of the lithium carbonate precipitation tank, the outlet of the lithium carbonate precipitation tank is connected to the inlet of the second washing filter, the slag discharge port of the second washing filter is connected to the inlet of the pulping tank, the outlet of the pulping tank is connected to the inlet of the centrifugal separator, the solid phase outlet of the centrifugal separator is connected to the inlet of the dryer, and the outlet of the dryer is connected to a lithium carbonate product discharge pipe.

2. A refining system for lithium aluminum fluorocarbonate according to claim 1, characterized in that: The washing water outlet of the first washing filter is communicated with the inlet of the dissolving tank.

3. A refining system for lithium aluminum fluorocarbonate according to claim 1, characterized in that: The filtrate outlet of the second washing filter is connected to the inlet of the carbon dioxide exhaust tank, and the side of the carbon dioxide exhaust tank is connected to an acid liquid feeding pipe; the outlet of the carbon dioxide exhaust tank is connected to the inlet of the MVR evaporation crystallizer, and the crystal phase outlet of the MVR evaporation crystallizer is connected to a sodium salt product discharge pipe.

4. A refining system for lithium aluminum fluorocarbonate according to claim 3, characterized in that: The mother liquor outlet of the MVR evaporation crystallizer is communicated with the inlet of the dissolving tank.

5. A refining system for lithium aluminum fluorocarbonate according to any one of claims 1 to 4, characterized in that: It also includes a sodium carbonate solution preparation tank, a filter and a second resin exchange column which are connected in sequence, and the outlet of the second resin exchange column is communicated with the inlet end of the pure sodium carbonate feeding pipe.

6. A refining system for lithium aluminum fluorocarbonate according to claim 5, characterized in that: The washing water outlet of the second washing filter and the washing water outlet of the centrifugal separator are both communicated with the inlet of the sodium carbonate solution preparation tank.

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