A method for preparing lithium carbonate by using waste lithium isooctanoate catalyst

Abstract

The present invention provides a method for preparing lithium carbonate by using waste lithium isooctanoate catalyst, which comprises the following steps: grinding and sieving the waste lithium isooctanoate catalyst, mixing it with water, and adding concentrated hydrochloric acid for leaching reaction; filtering the leaching slurry, adding an adsorbent, filtering, adding HCl and FeCl3·6H2O and stirring, controlling the pH to be 1.0 - 1.5 to obtain an aqueous phase; mixing tributyl phosphate and sulfonated kerosene to obtain an organic phase; mixing the aqueous phase and the organic phase for extraction, and then adding hydrochloric acid to the extraction phase for back-extraction to obtain an extract; performing dialysis to separate hydrochloric acid from the extract, adding lithium carbonate to the dialysate, adjusting the pH to be 4.0 - 5.0, adding a flocculant, subjecting to sedimentation, separation, concentration, adding the flocculant again for sedimentation and separation to obtain a lithium chloride solution; dropping the lithium chloride solution into a sodium carbonate solution to synthesize lithium carbonate, and through washing, drying, crushing, sieving and iron removal, battery-grade lithium carbonate is obtained. The scheme of the present invention realizes resource recycling, and the prepared product has high quality and low cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium carbonate preparation, and particularly relates to a method for preparing lithium carbonate by using waste lithium isooctanoate catalyst. Background Art

[0002] Lithium carbonate is an important lithium salt with wide uses and strong market application value. At present, there are mainly two production processes for lithium carbonate in the market, and the raw material sources of the two processes are different. One is extraction from salt lake brine, and the other is extraction from ore. Nowadays, with the rapid development of the new energy industry, the shortage of lithium resources has become the key bottleneck restricting the development of the industry. At the same time, the growth rate of various lithium-containing wastes is relatively fast. How to recycle various lithium resources has become a key issue for the industry to solve the problem of lithium resource shortage. Summary of the Invention

[0003] In view of this, the present invention provides a method for preparing lithium carbonate by using waste lithium isooctanoate catalyst.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for preparing lithium carbonate by using waste lithium isooctanoate catalyst, comprising the following steps:

[0006] Grind and screen the waste lithium isooctanoate catalyst to obtain lithium isooctanoate powder;

[0007] Mix the lithium isooctanoate powder with water and then add concentrated hydrochloric acid for leaching reaction to obtain a leaching slurry;

[0008] Filter the leaching slurry to obtain a filtrate and a filter residue;

[0009] Add an adsorbent to the filtrate for adsorption and then filter, and then add HCl and FeCl 3 ·6H 2 O and stir, control the pH to be 1.0 - 1.5 to obtain an aqueous phase;

[0010] Mix tributyl phosphate and sulfonated kerosene evenly to obtain an organic phase;

[0011] Mix the aqueous phase and the organic phase for extraction, oscillation, standing, and separation to obtain an extraction phase I and a raffinate phase I;

[0012] Add hydrochloric acid to the extraction phase I for back-extraction, oscillate, stand, and separate to obtain an extraction phase II and a raffinate phase II;

[0013] Perform dialysis on the extraction phase II to obtain hydrochloric acid and a dialysate;

[0014] Add lithium carbonate to the above dialysate, adjust the pH to be 4.0 - 5.0, and add a flocculant for the first sedimentation and separation to obtain a lithium-containing solution;

[0015] Concentrate the above lithium-containing solution, add a flocculant for secondary sedimentation and separation to obtain a lithium chloride solution;

[0016] Dropwise add the above lithium chloride solution into the sodium carbonate solution, react at 85 - 90 °C to synthesize lithium carbonate, and then through washing, drying, crushing, screening, and iron removal, battery-grade lithium carbonate is obtained.

[0017] Furthermore, it also includes concentrating the raffinate phase I to a Li content of 6 - 10 g / L, then adding HCl and FeCl 3 ·6H 2 O, adjusting the pH to 1.0 - 1.5 to obtain an aqueous phase for recycling;

[0018] It also includes using the hydrochloric acid obtained by dialysis for the preparation of the aqueous phase and the back-extraction step to achieve recycling.

[0019] Furthermore, the leaching reaction conditions are: temperature 5 - 20 °C, time 60 - 120 min, total mass of water and concentrated hydrochloric acid: mass of lithium isooctanoate powder = (4 - 7):1;

[0020] Among them, the lithium concentration in the leaching slurry is 6 - 10 g / L, and the molar ratio of H + and Li + is = (1.03 - 1.2):1, and the pH is 1.7 - 2.5.

[0021] Furthermore, the sieve mesh for sieving is 80 - 150 meshes, the adsorbent is activated carbon, and the addition amount of activated carbon is 0.5 wt% - 2 wt% of the filtrate mass.

[0022] Furthermore, it is characterized in that the molar ratio of iron to lithium in the aqueous phase is (1.2 - 1.7):1, and the stirring time is 10 - 30 min.

[0023] Furthermore, the volume ratio of tributyl phosphate to sulfonated kerosene in the organic phase is 1:(1 - 2.5).

[0024] Furthermore, in the extraction step, the volume ratio of the organic phase to the aqueous phase is (1 - 3):1, and the shaking time is 5 - 20 min.

[0025] Furthermore, in the back-extraction step, the hydrochloric acid concentration is 4 - 6 mol / L, the addition amount is 1.5 - 3 times the volume of the extraction phase I, and the shaking time is 5 - 15 min.

[0026] Furthermore, the dialysis uses an anion membrane for natural dialysis, the dialysis time is 30 - 60 h, and the lithium concentration after concentrating the lithium-containing solution is 26 - 30 g / L.

[0027] Further, the flocculant is phosphate starch;

[0028] The addition amount of phosphate starch during the first sedimentation is 0.1-0.5% of the mass of the dialysis solution, and the sedimentation time is 20-30h;

[0029] The addition amount of phosphate starch during the second sedimentation is 0.3%-0.7% of the mass of the lithium-containing solution, and the sedimentation time is 20-30h.

[0030] Preferably, the addition amount of phosphate starch during the first sedimentation is 0.2-0.4% of the mass of the dialysis solution, and the sedimentation time is 22-26h;

[0031] Preferably, the addition amount of phosphate starch during the second sedimentation is 0.3%-0.5% of the mass of the lithium-containing solution, and the sedimentation time is 22-26h.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The present invention uses waste lithium isooctanoate catalyst to prepare lithium carbonate, develops a new preparation process, realizes the recycling of resources, solves the pollution problem, and makes the prepared lithium carbonate product have low cost and more competitiveness.

[0034] (2) In the solution of the present invention, the raffinate I in the intermediate step is concentrated and reused, and the hydrochloric acid obtained by dialysis is also recycled, which not only improves the product yield but also reduces the use of raw materials, further reducing the cost.

[0035] (3) The lithium carbonate product prepared by the solution of the present invention has excellent performance and meets the standard "YS / T582-2013 Lithium Carbonate for Batteries". Description of the Drawings

[0036] Figure 1 It is the process flow chart of the solution of the present invention. Detailed Embodiments

[0037] The following further detailed description of the present invention is provided in conjunction with specific embodiments, so that those skilled in the art can understand the present invention more clearly.

[0038] Sources and physicochemical parameters of key test materials:

[0039] The waste lithium isooctanoate catalyst comes from the scrapped and contaminated materials generated during the production process of lithium isooctanoate manufacturers, and its main components are as follows:

[0040] Table 1 Composition of waste lithium isooctanoate catalyst

[0041]

[0042] Example 1

[0043] 1. A method for preparing lithium carbonate using waste lithium isooctanoate catalyst, characterized by comprising the following steps:

[0044] S1. Put the waste lithium isooctanoate catalyst into a grinder, grind it for 10 min, and pass through a 100-mesh sieve to obtain lithium isooctanoate powder.

[0045] S2. Mix the lithium isooctanoate powder with water, then add concentrated hydrochloric acid for leaching reaction to obtain a leaching slurry; wherein, the reaction temperature is 10 °C, the reaction time is 100 min, the total mass of water and concentrated hydrochloric acid: the mass of lithium isooctanoate powder = 5:1, control the lithium concentration in the leaching slurry to be 8 g / L, and the molar ratio of H + , Li + is = 1.1:1, and the pH at the end of leaching is 2.0.

[0046] S3. Filter the leaching slurry to obtain a filtrate and a filter residue; at this time, the filtrate mainly contains lithium chloride and a small amount of organic matter, and the filter residue is mainly isooctanoic acid (isooctanoic acid is slightly soluble in cold water, and its water solubility at 20 °C is 2 g / L). Analyze the lithium content in the filtrate, and the leaching rate of lithium is 92.24%; add 1 wt% of activated carbon based on the mass of the filtrate to the filtrate for adsorption and then filter, and then add HCl and FeCl 3 ·6H 2 O and stir for 20 min to obtain an aqueous phase; wherein, control the pH of the aqueous phase to be 1.2, and the molar ratio of iron to lithium is 1.5:1.

[0047] In this step, the activated carbon is mainly used to adsorb the organic matter contained in the filtrate; and the added HCl and FeCl 3 ·6H 2 O undergoes the following reaction: FeCl 3 + Cl- = FeCl 4 -.

[0048] S4. Mix tributyl phosphate (TBP) and sulfonated kerosene evenly according to a volume ratio of 1:2 to obtain an organic phase.

[0049] S5. Mix the above organic phase and aqueous phase according to a volume ratio of 2:1, shake and extract for 10 min, stand still, and separate to obtain extraction phase I and raffinate phase I. Among them, the obtained raffinate phase I is concentrated to a Li content of 8 g / L and then returned to step S3 to be prepared into an aqueous phase to achieve the purpose of recycling.

[0050] In this step, the following reaction occurs during the shaking extraction: 2TBP + Li + + FeCl 4 - = LiFeCl 4 ·2TBP.

[0051] S6. Add hydrochloric acid with a concentration of 5 mol / L and a volume twice that of the extraction phase I to the above extraction phase I, mix, shake for extraction for 10 min, let stand, and separate to obtain extraction phase II and raffinate phase II. At this time, the extraction phase II mainly contains a mixture of LiCl and HCl. Analyze the lithium content in the solution, and the extraction rate of lithium is 91.79%.

[0052] The following reaction occurs during the shaking extraction in this step: LiFeCl 4 ·2TBP + HCl = HFeCl 4 ·2TBP + LiCl.

[0053] S7. Perform dialysis on the above extraction phase II for 45 h using an anion membrane natural dialysis method to obtain hydrochloric acid and a dialysate. At this time, the separated hydrochloric acid can be used for the preparation of the aqueous phase in step S3 and the back-extraction step in step S6, achieving recycling.

[0054] The specific dialysis principle and steps are as follows: The dialysis cell is divided into two equal-sized left and right chambers by an anion exchange membrane. Place the extraction phase II in the left chamber and the same volume of clear water in the right chamber. Control the same stirring intensity on both sides. Driven by the concentration difference between the two chambers, H + , Cl - , and Li + in the left chamber all tend to enter the right chamber through the pores of the membrane. However, because the inner pore wall of the anion exchange membrane has a positive electric field, the anion Cl - in the left chamber preferentially passes through the membrane into the clear water in the right chamber over the cations H + and Li + . While Cl - diffuses and migrates, to maintain the electrical neutrality of the solution, it necessarily carries a stoichiometric amount of the cation H + or Li + through the membrane into the right chamber, increasing the ion concentration in the right chamber. Since the H + concentration in the extraction phase II is much greater than the Li + concentration, more H + will reach the right chamber, thus achieving the separation of hydrochloric acid.

[0055] S8. Add lithium carbonate to the above dialysate and control the pH to 4.5 to remove the excess H + in the dialysate and precipitate Fe and Al. Then add phosphate starch at 0.3% of the solution mass for sedimentation for 24 h, separate to obtain a lithium-containing solution.

[0056] S9. Concentrate the above lithium-containing solution to a lithium concentration of 28 g / L, and then add phosphate starch at 0.4% of the concentrated solution mass for sedimentation for 24 h, separate to obtain a lithium chloride solution.

[0057] S10. Add the above lithium chloride solution dropwise to the sodium carbonate solution, react at 85 - 90 °C to synthesize lithium carbonate, and then obtain battery-grade lithium carbonate through washing, drying, crushing, screening, and iron removal.

[0058] Example 2

[0059] S1. Put the waste lithium isooctanoate catalyst into a grinder, grind it for 15 min, and pass through a 150-mesh sieve to obtain lithium isooctanoate powder.

[0060] S2. Mix the lithium isooctanoate powder with water, add concentrated hydrochloric acid for leaching reaction to obtain a leaching slurry; among them, the reaction temperature is 5 °C, the reaction time is 120 min, the total mass of water and concentrated hydrochloric acid: the mass of lithium isooctanoate powder = 4:1, control the lithium concentration in the leaching slurry to be 10 g / L, and the molar ratio of H + , Li + is = 1.2:1, and the pH at the end of leaching is 1.7.

[0061] S3. Filter the leaching slurry to obtain a filtrate and a filter residue; at this time, the filtrate mainly contains lithium chloride and a small amount of isooctanoic acid, and the filter residue is mainly isooctanoic acid (isooctanoic acid is slightly soluble in cold water, and its water solubility at 20 °C is 2 g / L); add 0.5 wt% activated carbon based on the mass of the filtrate to the filtrate for adsorption and then filter, and then add HCl and FeCl 3 ·6H 2 O and stir for 10 min to obtain an aqueous phase; among them, control the pH of the aqueous phase to be 1.0, and the molar ratio of iron to lithium is 1.2:1.

[0062] S4. Mix tributyl phosphate and sulfonated kerosene evenly according to a volume ratio of 1:1 to obtain an organic phase.

[0063] S5. Mix the above organic phase and aqueous phase according to a volume ratio of 1:1, shake and extract for 5 min, stand still, and separate to obtain extraction phase I and raffinate phase I. Among them, the obtained raffinate phase I is concentrated to a Li content of 10 g / L and then returned to step S3 to prepare an aqueous phase to achieve the purpose of recycling.

[0064] S6. Add hydrochloric acid with a concentration of 4 mol / L and a volume 3 times that of extraction phase I to the above extraction phase I, mix, shake and extract for 5 min, stand still, and separate to obtain extraction phase II and raffinate phase II; at this time, extraction phase II mainly contains a mixture of LiCl and HCl. Analyze the lithium content in the solution, and the extraction rate of lithium is 92.15%.

[0065] S7. Dialyze the above extraction phase II by anion membrane natural dialysis for 60 h to obtain hydrochloric acid and a dialysate; at this time, the separated hydrochloric acid can be used for the preparation of the aqueous phase in the above step S3 and the back-extraction step in the above step S6 to achieve recycling.

[0066] S8. Add lithium carbonate to the above dialysis solution and control the pH to 5.0 to remove the excess H in the dialysis solution + and precipitate Fe and Al. Then, add 0.1% of phosphated starch based on the solution mass for sedimentation for 20 h, and separate to obtain a lithium-containing solution.

[0067] S9. Concentrate the above lithium-containing solution to make the lithium concentration 26 g / L. Then, add 0.3% of phosphated starch based on the concentrated solution mass for sedimentation for 20 h, and separate to obtain a lithium chloride solution.

[0068] S10. Dropwise add the above lithium chloride solution to a sodium carbonate solution and react at 85 - 90 °C to synthesize lithium carbonate. Then, through washing, drying, crushing, screening, and iron removal, battery-grade lithium carbonate is obtained.

[0069] Example 3

[0070] S1. Put the waste lithium isooctanoate catalyst into a grinder, grind for 5 min, and pass through an 80-mesh sieve to obtain lithium isooctanoate powder.

[0071] S2. Mix the lithium isooctanoate powder with water, add concentrated hydrochloric acid for leaching reaction to obtain a leaching slurry. Among them, the reaction temperature is 20 °C, the reaction time is 60 min, the total mass of water and concentrated hydrochloric acid: the mass of lithium isooctanoate powder = 7:1, control the lithium concentration in the leaching slurry to be 6 g / L, and the molar ratio of H + , Li + is = 1.03:1, and the pH at the end of leaching is 2.5.

[0072] S3. Filter the leaching slurry to obtain a filtrate and a filter residue. At this time, the filtrate mainly contains lithium chloride and a small amount of organic matter, and the filter residue is mainly isooctanoic acid (isooctanoic acid is slightly soluble in cold water, and the water solubility at 20 °C is 2 g / L); add 2 wt% of activated carbon based on the filtrate mass to the filtrate for adsorption and then filter, and then add HCl and FeCl 3 ·6H 2 O and stir for 30 min to obtain an aqueous phase. Among them, control the pH of the aqueous phase to be 1.5, and the molar ratio of iron to lithium is 1.7:1.

[0073] S4. Mix tributyl phosphate and sulfonated kerosene evenly according to a volume ratio of 1:2.5 to obtain an organic phase.

[0074] S5. Mix the above organic phase and aqueous phase according to a volume ratio of 3:1, shake and extract for 20 min, stand still, and separate to obtain an extraction phase I and a raffinate phase I. Among them, the obtained raffinate phase I is also concentrated to a Li content of 6 g / L and then returned to step S3 to prepare an aqueous phase to achieve the purpose of recycling.

[0075] S6. Add hydrochloric acid with a concentration of 6 mol / L and a volume 1.5 times that of the above extraction phase I to the above extraction phase I, mix, shake and extract for 15 min, let stand, and separate to obtain extraction phase II and raffinate phase II; at this time, the extraction phase II is mainly a mixture of LiCl and HCl. Analyze the lithium content in the solution, and the extraction rate of lithium is 92.47%.

[0076] S7. Perform dialysis on the above extraction phase II by the method of natural dialysis with an anion membrane for 30 h to obtain hydrochloric acid and dialysis solution; at this time, the separated hydrochloric acid can be used for the preparation of the aqueous phase in the above step S3 and the back-extraction step in the above step S6 to achieve recycling.

[0077] S8. Add lithium carbonate to the above dialysis solution and control the pH to 4.0 to remove the excess H + in the dialysis solution and precipitate Fe and Al, and then add phosphate starch accounting for 0.5% of the solution mass to settle for 30 h, and separate to obtain a lithium-containing solution.

[0078] S9. Concentrate the above lithium-containing solution to make the lithium concentration 30 g / L, and then add phosphate starch accounting for 0.7% of the concentrated solution mass to settle for 30 h, and separate to obtain a lithium chloride solution.

[0079] S10. Drop the above lithium chloride solution into the sodium carbonate solution and react at 85 - 90 °C to synthesize lithium carbonate, and then through washing, drying, crushing, screening, and iron removal, battery-grade lithium carbonate is obtained.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing lithium carbonate using waste lithium isooctanoate catalyst. Its raw materials and methods are basically the same as those in Example 1, except that: in step S2, the total mass of water and concentrated hydrochloric acid: the mass of lithium isooctanoate powder = 2:1.

[0082] The leaching rate of lithium in the final waste lithium isooctanoate catalyst is 61.24%.

[0083] Comparative Example 2

[0084] This comparative example provides a method for preparing lithium carbonate using waste lithium isooctanoate catalyst. Its raw materials and methods are basically the same as those in Example 1, except that: in step S6, the concentration of hydrochloric acid is 2 mol / L.

[0085] The extraction rate of lithium in the final back-extraction process is 24.33%.

[0086] Comparative Example 3

[0087] This comparative example provides a method for preparing lithium carbonate using waste lithium isooctanoate catalyst. Its raw materials and methods are basically the same as those in Example 1, except that: in step S9, the settling time is 40 h.

[0088] Finally, it leads to a decrease in the adsorption capacity of phosphate starch, an increase in impurity ions in the solution, and some impurity elements in the synthesized lithium carbonate exceeding the scope of "YS / T 582-2013 Lithium Carbonate for Battery Grade". When using the phosphate starch flocculant, with the prolongation of the flocculation time, the flocculation effect increases accordingly. However, after exceeding the optimal sedimentation time, due to the hydrophilic effect of some phosphate starch, the adsorption capacity at the end of the chain segment decreases, causing the already adsorbed impurity ions to be suspended again, thus reducing the flocculation effect.

[0089] The indicators of the lithium carbonate prepared in Examples 1-3 and Comparative Example 3 were detected according to the standard "YS / T582-2013 Lithium Carbonate for Battery Grade", and the results are shown in the following table:

[0090] Table 2 Chemical Composition of Lithium Carbonate

[0091]

[0092] In the present invention, if no specific raw materials are described, they are all existing substances and can be directly purchased from the market.

[0093] The above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing lithium carbonate using waste lithium isooctanoate catalyst, characterized in that, it includes the following steps: Grind and sieve the waste lithium isooctanoate catalyst to obtain lithium isooctanoate powder; Mix the lithium isooctanoate powder with water and then add concentrated hydrochloric acid for leaching reaction to obtain a leaching slurry; Filter the leaching slurry, add an adsorbent to the filtrate for adsorption and then filter it, and then add HCl and FeCl 3 •6H 2 O and stir, control the pH to be 1.0 - 1.5 to obtain an aqueous phase; Mix tributyl phosphate and sulfonated kerosene evenly to obtain an organic phase; Mix the aqueous phase and the organic phase for extraction, shaking, standing, and separation to obtain extraction phase I and raffinate phase I; Add hydrochloric acid to extraction phase I for back-extraction, shake, stand, and separate to obtain extraction phase II and raffinate phase II; Perform dialysis on extraction phase II to obtain hydrochloric acid and a dialysate; Add lithium carbonate to the above dialysate, adjust the pH to 4.0 - 5.0, and add a flocculant for the first sedimentation, separation, to obtain a lithium-containing solution; Concentrate the above lithium-containing solution, add a flocculant for the second sedimentation, separation, to obtain a lithium chloride solution; Dropwise add the above lithium chloride solution to a sodium carbonate solution, react at 85 - 90 °C to synthesize lithium carbonate, and then through washing, drying, crushing, screening, and iron removal, battery-grade lithium carbonate is obtained; The sedimentation time of the second sedimentation is 20 - 30 h.

2. The method according to claim 1, characterized in that, It also includes concentrating the raffinate phase I until the Li content reaches 6 - 10 g / L, then adding HCl and FeCl 3 •6H 2 O, adjusting the pH to 1.0 - 1.5 to obtain an aqueous phase for recycling; it further includes using the hydrochloric acid obtained by dialysis for the preparation of the aqueous phase and the back-extraction step to achieve recycling.

3. The method according to claim 1 or 2, characterized in that, the leaching reaction conditions: temperature 5 - 20 °C, time 60 - 120 min, total mass of water and concentrated hydrochloric acid: mass of lithium isooctanoate powder = (4 - 7):1; Among them, the lithium concentration in the leaching slurry is 6-10 g / L, H + and Li + The molar ratio is =(1.03-1.2):1, and the pH is 1.7-2.

5.

4. The method according to claim 1 or 2, characterized in that, the sieve mesh for screening is 80 - 150 meshes, the adsorbent is activated carbon, and the addition amount of activated carbon is 0.5 wt% - 2 wt% of the filtrate mass.

5. The method according to claim 1 or 2, characterized in that, the molar ratio of iron to lithium in the aqueous phase is (1.2 - 1.7):

1.

6. The method according to claim 1 or 2, characterized in that, the volume ratio of tributyl phosphate to sulfonated kerosene in the organic phase is 1:(1 - 2.5).

7. The method according to claim 1 or 2, characterized in that, the volume ratio of the organic phase to the aqueous phase in the extraction step is (1 - 3):

1.

8. The method according to claim 1 or 2, characterized in that, the hydrochloric acid concentration in the back-extraction step is 4 - 6 mol / L, and the addition amount is 1.5 - 3 times the volume of extraction phase I.

9. The method according to claim 1 or 2, characterized in that, the dialysis uses an anion membrane for natural dialysis, the dialysis time is 30 - 60 h, and the lithium concentration after concentrating the lithium-containing solution is 26 - 30 g / L.

10. The method according to claim 1 or 2, characterized in that, the flocculant is phosphate starch; the addition amount of phosphate starch during the first sedimentation is 0.1 - 0.5% of the dialysate mass, and the sedimentation time is 20 - 30 h; the addition amount of phosphate starch during the second sedimentation is 0.3% - 0.7% of the lithium-containing solution mass, and the sedimentation time is 24 h.

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