CN101125668A - Method for producing low-magnesium battery-stage lithium carbonate from lithium sulfate solution - Google Patents

Abstract

The invention provides a method to produce a low-magnesium battery grade lithium carbonate from lithium sulfate solution. The method comprises the steps that: (1) purification treatment of lithium sulfate solution as following: lithium sulfate solution is co-precipitated to lower the impurities ions Fe3+, Mg2+, Al3+ and Ca2+, and condensed and filtered to further eliminate impurities, and obtain purification residues and a pure finish solution of lithium sulfate; (2) soda is dissolved and added with purification residues obtained from the purified lithium sulfate solution, and used for a filtering media to filter calcium and magnesium and obtain purified soda solution; (3) the purified soda solution is added with complexant EDTA, and stirred for complexation reaction, and slowly added with condensed and impurities eliminated pure finish solution of lithium sulfate, and a crude lithium carbonate is prepared; (4) the crude lithium carbonate is stirred, cleaned, dried and smashed, thus obtaining the low-magnesium battery grade lithium carbonate. The method of the invention has the advantages of simple production technique, stable product quality and low cost, and expertly employs the waste residues in the process, not only solves the difficulty of impurities elimination for soda, but also enhances the recycling ratio of lithium, which is suitable for the production application of the positive pole material of Li-ion battery.

Description

The method of producing low-magnesium battery-stage lithium carbonate from lithium sulfate solution

Technical field:

The present invention is relevant with the method that lithium sulfate solution prepares the low-magnesium battery level lithium carbonate.

Technical background:

Because lithium and lithium compound have special property, use more and more widely in the many fields of national economy.The lithium cell industry development is very fast in recent years, and the Quilonum Retard demand of producing anode material of lithium battery not only increases considerably, and Quilonum Retard is progressively replaced by battery-level lithium carbonate cheaply by initial pure Lithium Carbonate.Along with the extensive utilization of battery-level lithium carbonate, the magnesium in the product is had higher requirement again.Require in the past in the product Mg content be control less than 150PPm, now require Mg content less than 50PPm.

Existing positive electrode material is produced the production technique of the pure Lithium Carbonate of using: mainly be to utilize Quilonum Retard or lithium hydroxide to be raw material, by repeatedly hydrogenation decomposition or carbonization, stir to wash and form, its raw materials cost is very high, the while complex process, and the lithium rate of recovery is low.

Introduced in the concentrated brine that contains lithium about 6% during chemical industry mineral and processing " method of lithium is put forward in demagging in the bittern " (calendar year 2001) digest is wanted and at first magnesium has been removed with the form of magnesium hydroxide, add circulation lime treatment mother liquor then in the bittern after demagging, with the precipitation Quilonum Retard.

Chinese invention patent ZL011234792 " a kind of method of extracting Quilonum Retard from the high Mg/Li ratio salt lake saline " utilizes the solar evaporation pond that the salt lake intercrystalline bittern is carried out spontaneous evaporation to concentrate, fractional crystallizaton separates and adds precipitation agent, form difficulty soluble salt (magnesiumcarbonate or magnesium hydroxide) with magnesium ion, after the solid-liquid separation, feed liquid is through regulating the pH value, evaporation concentration, the NaCl crystallization is separated out, lithium chloride concentration should reach 100g/l, with soda ash is precipitation agent, the Quilonum Retard precipitation is separated out, through separating, drying makes lithium carbonate product.

Chemical industry tradition is removed magnesium method and is all adopted chemical coprecipitation, and magnesium is separated from liquid phase with forms such as magnesium hydroxide, magnesium oxalate or magnesiumcarbonate, and demagging is to add lime as soda industry, and magnesium is removed with magnesium hydroxide.

Mg content can not reach the requirement of producing the low-magnesium battery level lithium carbonate all above 50PPm in the product that above-mentioned each method is produced.

Summary of the invention:

Constant product quality, the method for the producing low-magnesium battery-stage lithium carbonate from lithium sulfate solution that cost is low are provided in order to provide a kind of production technique simple.

The object of the present invention is achieved like this:

The method of producing low-magnesium battery-stage lithium carbonate from lithium sulfate solution of the present invention, this method comprises the steps:

(1) purifying treatment of lithium sulfate solution: adopt the Fe in the chemical coprecipitation reduction lithium sulfate solution ³⁺, Mg ²⁺, Al ³⁺, Ca ²⁺Deng foreign ion, reconcentration filters further removes impurity, obtains to purify the intact only liquid of slag and Lithium Sulphate;

(2) the purification slag that soda ash dissolving, adding preparation lithium sulfate solution are obtained obtains the purification soda ash solution as the filtration medium that filters deliming, magnesium;

(3) complexing agent EDTA is joined in the purification soda ash solution, stir complex reaction, slowly add again, prepare the crude product Quilonum Retard through the intact only liquid of the Lithium Sulphate of concentrating and impurity removing;

(4) the crude product Quilonum Retard wash drying through stirring, pulverize the low-magnesium battery level lithium carbonate.

Above-mentioned method concrete steps are as follows:

(1) lithium sulfate solution purifying treatment:

(a) lithium sulfate solution is warming up to 70-90 ℃, regulates the pH value with NaOH and reach 9.0-11, reacted 10-15 minute, remove most Fe in the solution ²⁺, Fe ³⁺, Al ³⁺, Mg ²⁺Deng impurity metal ion;

Reaction principle: Al ³⁺+ OH ^-→ Al (OH) ₃↓

Fe ³⁺+OH ^-→Fe(OH) ₃↓

Mg ²⁺+OH ^-→Mg(OH) ₂↓

Fe ²⁺+OH ^-→Fe(OH) ₂↓

(b) according to Ca in the lithium sulfate solution ²⁺Concentration adds the yellow soda ash solid by theoretical amount excessive 4～6%, reacts 20-40 minute, detects its CO ₃ ^2-It is reaction end that content reaches 0.2-0.7g/L, to remove the Ca in the solution ²⁺, filter and be purified lithium sulfate solution and purification slag;

Reaction principle: Ca ²⁺+ CO ₃ ^2-→ CaCO ₃↓

(c) concentration: the scavenging solution evaporation concentration to 50-65g/L, is filtered and further removed Mg (OH) ₂, CaCO ₃Deng impurity, obtain the intact only liquid (Li of Lithium Sulphate ₂SO ₄Concentrated solution);

(2) soda ash dissolving, filtration deliming, magnesium:

Soda ash joined according to the concentration of 300 ± 10g/L in 80-90 ℃ the deionized water, be mixed with solution, then by the purification slag that adds the preceding operation of 30-60kg in every cubic metre of soda ash liquid, stir, left standstill 20-40 minute, filter, remove impurity such as most of residue calcium, magnesium, obtain to purify soda ash solution;

Contain a large amount of calcium, magnesium addition (general Ca in the soda ash solution in the soda ash solution ²⁺=0.04g/L, Mg ²⁺=0.06g/L), if directly be used for preparing Quilonum Retard, quality product can not reach requirement; Soda ash solution is weakly alkaline, and PH about 10, and wherein the existence form of calcium, magnesium addition is CaCO ₃, MgCO ₃, Mg (OH) ₂, but very tiny, even adopt mocromembrane filtration, microtubule filtration etc. all can't direct filtration to remove.In conjunction with the Ca in the lithium sulfate solution after the preceding operation lithium sulfate solution purifying treatment ²⁺, Mg ²⁺Very low, think by comparative analysis: the purification slag is the Al (OH) by the part colloidal ₃, Mg (OH) ₂, Fe (OH) ₃And CaCO ₃Deng composition, be a kind of have good polymerization and adsorbing filtration medium, can reunite effectively and adsorbent solution in MgCO ₃, CaCO ₃, Mg (OH) ₂Etc. fine impurities, thereby reach Ca in the lithium sulfate solution ²⁺, Mg ²⁺Very low.Therefore utilize polymerization and the characterization of adsorption that purifies slag, in soda ash solution, add the purification slag, thereby reach the Ca that reduces in the soda ash solution ²⁺, Mg ²⁺Impurity.And contain a large amount of Li in the purification slag ₂SO ₄,, can reclaim Li wherein by joining in the soda ash liquid ₂SO ₄

(3) complexing demagging, sinker:

(a) adding concentration earlier in the reactor is the purification soda ash solution of 300 ± 10g/L, adds complexing agent EDTA again, and EDTA presses 1-2Kg/m ³Alkali lye adds, and reaction 10-20min is to remove wherein Ca ²⁺, Mg ²⁺, Pb ²⁺Deng metal ion, simultaneously excessive in order to residual Mg in the intact only liquid of the Lithium Sulphate of removing down the operation adding ²⁺,

Mg+Y-→MgY

(b) in reactor, add the intact only liquid (Li of Lithium Sulphate equably ₂SO ₄Concentrated solution), 80-150 rev/min of control mixing speed, reinforced time 60-150 minute, stir while feeding in raw material, reinforced finishing reacts 30-60 minute again, and centrifugation obtains the crude product of Quilonum Retard then, centrifugation obtains the crude product of Quilonum Retard, complex compound such as magnesium, calcium impurity is dissolved among the mother liquor, thereby separates with Quilonum Retard

2Li ⁺+CO ₃ ^2-→Li ₂CO ₃↓

(4) stir wash, dry, pulverize: in the crude product of Quilonum Retard, add water, stir by solid-to-liquid ratio 1: 3-4 and be washed till less twice, stir at every turn and wash centrifugation after 10-20 minute; Dry again, be crushed to particle diameter＜6 μ m, make the low-magnesium battery level lithium carbonate.

The present invention by chemical precipitation method reduce Mg content in the lithium sulfate solution, the purification slag that utilizes the preparation lithium sulfate solution reduces wherein Mg as the filtration medium of soda ash filtering and impurity removing ²⁺Concentration, and adopt EDTA as complexing agent with in lithium sulfate solution and the soda ash solution not fully the magnesium hydroxide of filtering separation change into soluble complexes, realize the preparation of low-magnesium battery level lithium carbonate, thereby satisfy the individual demand in market.

It is simple that the present invention has production technique, constant product quality, and cost is low; The ingenious waste residue that utilizes in the flow process not only solves a soda ash removal of impurities difficult problem, improves the lithium rate of recovery simultaneously; And creatively adopt characteristics such as complexing demagging new technology.The production application of suitable anode material for lithium-ion batteries.

Description of drawings:

Fig. 1 is a production method process flow sheet of the present invention.

Embodiment:

Embodiment 1:

Present embodiment 1 method may further comprise the steps (referring to Fig. 1)

1. with Li ₂O content is the 6.0m of 20g/L ³Lithium sulfate solution is warming up to 70 ℃, adds 10kg sodium hydroxide, reacts 10 minutes, and the pH value reaches 10, adds Na then ₂CO ₃8kg reacted 30 minutes, detected CO ₃ ^2-Reach 0.5g/L, filter and be purified Lithium Sulphate liquid and purification slag, and record purification lithium sulfate solution Ca ²⁺=0.0025g/L, Fe ³⁺=0.0003g/L, Mg ²⁺=0.0018g/L; To purify the lithium sulfate solution evaporation concentration then to 60g/L, and filter and obtain the intact only liquid of Lithium Sulphate;

2. with 1.4m ³Water of condensation is warming up to 80 ℃, adds 420kg soda ash then, is stirred to dissolving fully, adds to purify slag 60kg again, leaves standstill filtration in 20 minutes, must purify soda ash solution, and record Na ₂CO ₃=298g/L, Ca ²⁺=0.003g/L, Mg ²⁺=0.004g/L (does not do to have polymerization and adsorbing filtration medium if do not add the purification slag, general Ca in soda ash solution during direct filtration ²⁺=0.04g/L, Mg ²⁺=0.06g/L);

3. will purify soda ash solution and add in the reactor, be warming up to 95 ℃, add complexing agent EDTA1.4kg, react 10 minutes, begin to add the intact only liquid of Lithium Sulphate then, the intact only about 1.9m of liquid measure ³, 80 rev/mins of control mixing speed, the reinforced 60 minutes time, stir while feeding in raw material, reinforced finishing reacts 30-60 minute again, and centrifugation obtains the crude product of Quilonum Retard then;

4. add 1m in the crude product of Quilonum Retard ³Water of condensation is warming up to more than 95 ℃, stir wash 10 minutes after, centrifugation repeats to stir again and washes once, at 250 ℃ of following baking 30min, is crushed to median size＜6 μ m with micronizer mill more then, puts in storage after the clean packaging, produces qualified low magnesium lithium carbonate product.

Embodiment 2:

Present embodiment 2 methods may further comprise the steps (referring to Fig. 1):

1. with Li ₂O content is the 5.65m of 25g/L ³Lithium sulfate solution is warming up to 80 ℃, adds 12kg sodium hydroxide, reacts 15 minutes, regulates the pH value and reaches 11, adds Na ₂CO ₃10kg reacted 30 minutes, detected CO ₃ ^2-Reach 0.4g/L, filter and be purified Lithium Sulphate liquid and purification slag, and record purification Lithium Sulphate liquid Ca ²⁺=0.001g/L, Fe ³⁺=0.00025g/L, Mg ²⁺=0.0015g/L; To purify Lithium Sulphate liquid evaporation concentration then to 55g/L, and filter and obtain the intact only liquid of Lithium Sulphate;

2. with 1.65m ³Water of condensation is warming up to 85 ℃, adds 500kg soda ash then, is stirred to fully dissolving, adds to purify slag 30kg again, leave standstill 30min (minute) filter, must purify soda ash solution, and record Na ₂CO ₃=305g/L, Ca ²⁺=0.0035g/L, Mg ²⁺=0.0028g/L (does not do to have polymerization and adsorbing filtration medium if do not add the purification slag, general Ca in soda ash solution during direct filtration ²⁺=0.04g/L, Mg ²⁺=0.06g/L);

3. soda ash solution is added in the reactor, be warming up to 95 ℃, add complexing agent EDTA 2.5kg, reacted 15 minutes, begin to add the intact only liquid of Lithium Sulphate then, the intact only about 2.45m of liquid measure ³, 120 rev/mins of control mixing speed, the reinforced 120 minutes time, stir while feeding in raw material, reinforced finishing reacts 30-60 minute again, and centrifugation obtains the crude product of Quilonum Retard then;

4. add 1.2m in the crude product of Quilonum Retard ³Water of condensation is warming up to more than 95 ℃, stir wash 15 minutes after, centrifugation repeats to stir again and washes once, at 200 ℃ of following baking 40min, is crushed to median size＜6 μ m with micronizer mill more then, puts in storage after the clean packaging, produces qualified low magnesium lithium carbonate product.

Embodiment 3:

Present embodiment may further comprise the steps (referring to Fig. 1):

1. with Li ₂O content is the 4.05m of 27g/L ³Lithium sulfate solution is warming up to 90 ℃, adds 9kg sodium hydroxide, reacts 12 minutes, regulates the pH value and reaches 9, adds Na ₂CO ₃6kg reacted 30 minutes, detected CO ₃ ^2-Reach 0.3g/L, filter and be purified lithium sulfate solution and purification slag, and record purification lithium sulfate solution Ca ²⁺=0.0036g/L, Fe ³⁺=0.00035g/L, Mg ²⁺=0.004g/L; To purify the lithium sulfate solution evaporation concentration then to 65g/L, and filter and obtain the intact only liquid of Lithium Sulphate;

2. with 1.35m ³Water of condensation is warming up to 90 ℃, adds 400kg soda ash then, is stirred to dissolving fully, adds to purify slag 45kg again, leaves standstill filtration in 40min minute, must purify soda ash solution, and record Na ₂CO ₃=295g/L, Ca ²⁺=0.0025g/L, Mg ²⁺=0.0034g/L (does not do to have polymerization and adsorbing filtration medium if do not add the purification slag, general Ca in soda ash solution during direct filtration ²⁺=0.04g/L, Mg ²⁺=0.06g/L);

3. soda ash solution is added in the reactor, be warming up to 95 ℃, add complexing agent EDTA 2.7kg, reacted 20 minutes, begin to add the intact only liquid of Lithium Sulphate then, the intact only about 1.6m of liquid measure ³, 150 rev/mins of control mixing speed, the reinforced 150 minutes time, stir while feeding in raw material, reinforced finishing reacts 30-60 minute again, and centrifugation obtains the crude product of Quilonum Retard then, carries out the crude product that centrifugation obtains Quilonum Retard;

4. add 0.9m in the crude product of Quilonum Retard ³Water of condensation is warming up to more than 95 ℃, stir wash 20 minutes after, centrifugation repeats to stir again and washes once, at 220 ℃ of following baking 40min, is crushed to median size＜6 μ m with micronizer mill more then, puts in storage after the clean packaging, produces qualified low magnesium lithium carbonate product.

Lithium sulfate solution in the various embodiments described above is by the make the transition solution of roasting, acidizing fired, leaching preparation of lithium concentrate.The qualified low magnesium lithium carbonate product quality that the various embodiments described above method is produced sees Table 1:

The foregoing description is that foregoing of the present invention is further described, but this should be interpreted as that the scope of the above-mentioned theme of the present invention only limits to the foregoing description.All technology that realizes based on foregoing all belong to scope of the present invention.

Table 1: low-magnesium battery-stage lithium carbonate product quality table

Component target	Embodiment 1	Embodiment 2	Embodiment 3
				Li 2CO 3％≥	99.62	99.57	99.71
Na％≤	0.02	0.015	0.018
				K％≤	0.0002	0.0005	0.0006
Ca％≤	0.0004	0.0006	0.0008
				Cu％≤	0.0015	0.0019	0.0023
Pb％≤	0.0001	0.00018	0.0016
				Mg％≤	0.0013	0.0015	0.0025
Ni％≤	0.0025	0.0023	0.0021
				Mn％≤	0.00073	0.00082	0.00065
Zn％≤	0.00083	0.00095	0.00072
				Al％≤	0.0078	0.0009	0.0014
Si％≤	0.0016	0.0015	0.0023
				Cl -％≤	0.0015	0.0018	0.0016
SO 4 2-％≤	0.067	0.072	0.057
				H 2O％≤	0.25	0.32	0.30
Mean particle size (μ m)	5.6	4.5	5.3

Claims (2)

1. the method for producing low-magnesium battery-stage lithium carbonate from lithium sulfate solution, this method comprises the steps:

(1) purifying treatment of lithium sulfate solution: adopt chemical coprecipitation to reduce Fe in the lithium sulfate solution ³⁺, Mg ²⁺, Al ³⁺, Ca ²⁺Foreign ion, reconcentration filter further to remove impurity, obtain to purify the intact only liquid of slag and Lithium Sulphate;

(2) the purification slag that soda ash dissolving, adding are purified the lithium sulfate solution acquisition filters acquisition and purifies soda ash solution as the filtration medium that filters deliming, magnesium;

(3) complexing agent EDTA is joined in the purification soda ash solution, stir complex reaction, slowly add again, prepare the crude product Quilonum Retard through the intact only liquid of the Lithium Sulphate of concentrating and impurity removing;

(4) the crude product Quilonum Retard wash drying through stirring, pulverize the low-magnesium battery level lithium carbonate.

2. the method for producing low-magnesium battery-stage lithium carbonate from lithium sulfate solution as claimed in claim 1 is characterized in that comprising the steps:

(1) purifying treatment of lithium sulfate solution:

(a) lithium sulfate solution is warming up to 70-90 ℃, regulates the pH value with NaOH and reach 9.0-11, reacted 10-15 minute, remove most Fe in the solution ²⁺, Fe ³⁺, Al ³⁺, Mg ²⁺Impurity metal ion;

(b) according to Ca in the lithium sulfate solution ²⁺Concentration adds the yellow soda ash solid by theoretical amount excessive 4～6%, reacts 20-40 minute, detects its CO ₃ ^2-It is reaction end that content reaches 0.2-0.7g/L, to remove the Ca in the solution ²⁺, filter and be purified liquid and purification slag;

(c) concentration: the scavenging solution evaporation concentration to 50-65g/L, is filtered and further removed Mg (OH) ₂, CaCO ₃Impurity obtains the intact only liquid of Lithium Sulphate;

(2) soda ash dissolving, filtration deliming, magnesium:

Soda ash joined according to the concentration of 300 ± 10g/L in 80-90 ℃ the deionized water, be mixed with solution, then by the purification slag that adds the preceding operation of 30-60kg in every cubic metre of soda ash liquid, stir, left standstill 20-40 minute, filter, remove most of residue calcium, magnesium addition, be purified soda ash solution;

(3) complexing demagging, sinker:

(a) adding concentration earlier in the reactor is the purification soda ash solution of 300 ± 10g/L, adds complexing agent EDTA again, and EDTA presses 1-2Kg/m ³Alkali lye adds, and reaction 10-20min is to remove wherein Ca ²⁺, Mg ²⁺, Pb ²⁺Metal ion, simultaneously excessive in residual Mg in the intact only liquid of the Lithium Sulphate of removing down the operation adding ²⁺

(b) in reactor, add the intact only liquid of Lithium Sulphate equably, 80-150 rev/min of control mixing speed, reinforced time 60-150 minute, stir while feeding in raw material, reinforced finishing reacts 30-60 minute again, centrifugation obtains the crude product of Quilonum Retard then, and magnesium, calcium complex impurity are dissolved among the mother liquor, thereby separate with Quilonum Retard;

(4) stir wash, dry, pulverize: in the crude product of Quilonum Retard, add water, stir by solid-to-liquid ratio 1: 3-4 and be washed till fewly twice, stir at every turn and wash centrifugation after 10-20 minute, again drying, be crushed to particle diameter＜6 μ m, make the low-magnesium battery level lithium carbonate.

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