CN106276988A - A kind of method preparing battery-level lithium carbonate for precipitant with potassium carbonate - Google Patents

Abstract

A method for preparing battery-grade lithium carbonate by using potassium carbonate as a precipitating agent, involving the technical field of chemical industry, which comprises the following steps: preparation of lye → impurity removal → ion exchange → evaporation and concentration → reaction aging → filtration and washing → drying → finished product The beneficial effect of the present invention is: the present invention prepares lithium carbonate with salt of wormwood as precipitating agent and lithium chloride reaction, and the mother liquor obtained at last is the higher potassium chloride solution of purity, and this mother liquor can be directly used in the production of potassium chloride or Potassium carbonate, no waste generation; the more serious wall sticking problem in the reaction process is solved by adding seed crystals and the reaction temperature; the combination of seed crystals, reaction temperature, stirring speed, and ultrasound avoids the aggregation of lithium carbonate crystals and wide particle size distribution question.

Description

A method for preparing battery-grade lithium carbonate with potassium carbonate as precipitant

1. Technical field

The invention relates to the technical field of chemical engineering, in particular to a method for preparing battery-grade lithium carbonate by using potassium carbonate as a precipitating agent.

2. Background technology

Lithium carbonate is the most basic lithium salt among lithium compounds, and is the main raw material for preparing other lithium compounds and lithium alloys. In recent years, as lithium carbonate has emerged in high-tech fields such as new energy and new materials, especially in the field of electric vehicles, it has shown attractive application prospects.

my country has abundant salt lake lithium resources. With the joint efforts of scientific and technological workers and the business community, a complete lithium industry chain integrating the development of lithium resources in Salt Lake, the production of lithium battery materials, lithium battery manufacturing, and the assembly of pure electric vehicles has gradually been formed. In recent years, salt lake enterprises such as Qinghai Salt Lake Industry Co., Ltd., Qinghai CITIC Guoan Technology Development Co., Ltd., and Qinghai Lithium Industry Co., Ltd. have adopted the adsorption method, calcination method and ion selective migration method to realize the industrialization of lithium extraction technology from salt lake brine with high magnesium-lithium ratio. Lithium carbonate is produced by reacting and precipitating (crystallizing) the extracted lithium chloride solution with sodium carbonate (soda ash).

At present, the preparation methods of battery grade lithium carbonate mainly include sulfuric acid method, carbonization method and electrodialysis method.

The sulfuric acid method is mainly used to extract lithium from lithium ores such as spodumene and lepidolite. The basic process is as follows: first, the lithium concentrate is transformed into roasted, acidified and roasted, and then leached with sulfuric acid to convert it into a lithium sulfate solution. After further separation of the metal After impurity ion, add sodium carbonate and carry out precipitation, make battery grade lithium carbonate (Xu Longquan, Zeng Zuliang, Liang Hu, Tu Mingjiang, Mi Maolong, sulfuric acid method produces battery grade lithium carbonate, CN1267636; Yang Chunhui, Wang Yunxu, Zhao Jiang , Zhang Xiaohong, Li Chaohong, A clean production method of battery-grade lithium carbonate, CN103086405A; Yao Kailin, Jinpeng, Huo Liming, Huang Chunlian, Tu Mingjiang, Liang Pingwu, Zhang Bingyuan, Zhao Wei, Method for producing low-magnesium battery-grade lithium carbonate from lithium sulfate solution CN101125668), the sulfuric acid method has problems such as dependence on imports of high-quality lithium concentrate, high energy consumption in the production process, difficult treatment of tailings and waste water, and serious pollution. Since 1996, lithium extraction from salt lake brine has gradually become the leading role in the global lithium industry. At present, 80% of the lithium carbonate products produced globally are extracted from salt lake brine.

The raw materials used in the carbonization method mainly come from lithium carbonate containing certain impurities produced by salt lake enterprises. The basic process is as follows: firstly, lithium carbonate and water are prepared into a suspension, and then carbon dioxide is introduced to convert the insoluble lithium carbonate into carbonate with high solubility. Lithium hydrogen, filter to remove insoluble impurities, and then remove soluble impurities by ion exchange and other methods, and then obtain battery-grade lithium carbonate by thermal decomposition reaction or adding high-purity lithium hydroxide (Peng Qiuhua, Dai Yang, Xu Zhongji, deep carbonization method to treat carbonic acid Process for producing battery-grade lithium carbonate from salt-type lithium concentrate, CN102502720A; Su Kang, Du Hongwen, Xiang Dong, An industrial method for producing battery-grade lithium carbonate or high-purity lithium carbonate, CN102583453A; Tan Xiumin, Zhang Lizhen, Zhang Xiufeng, Li Qi, Zhao Hengqin , a method for preparing battery-grade lithium carbonate or high-purity lithium carbonate using industrial-grade lithium carbonate, CN103539169A; Li Weida, Yuan Aiwu, Zhou Guiyue, Zhang Junmei, a method for producing battery-grade lithium carbonate from lithium concentrate, CN103708505A), the carbonization method will be extended The technological process increases equipment investment, greatly increases production costs, and there are also problems such as engineering difficulties.

The electrodialysis method uses salt lake brine to separate Li+ and Mg2+ through electrodialysis to obtain lithium chloride, and then precipitates with sodium carbonate to obtain lithium carbonate. The magnesium ions and lithium ions in the raw brine are migrated. When the raw brine passes through the selective separation membrane, monovalent ions such as lithium and sodium pass through the membrane, and divalent ions such as magnesium and calcium are isolated. After separation, low-magnesium Lithium-rich brine with a low ratio of magnesium to lithium, deep removal of impurities such as Ca2+, Mg2, K+, S042- +, etc. And after three-effect evaporation and concentration, the concentrated lithium-rich brine is added with sodium carbonate to precipitate lithium at a certain temperature, then press-filtered, pulp washed, centrifuged and washed, and finally dried and cooled to obtain the battery-grade lithium carbonate product (Ma Peihua , Li Zengrong, Li Jian, Zhou Xiaojun, Liu Guowang, Zhao Ying, Tang Faman, Ma Jun, A method of using salt lake brine to produce battery-grade carbon dioxide, CN102976367; Ma Peihua, Guo Yongnan, Direct production of batteries from salt lake brine with high magnesium-lithium ratio Level lithium carbonate method, CN105540619A), the electrodialysis process is long, the water consumption and power consumption of multi-stage electrodialysis are high, and the production cost is too high.

There are also literature reports that lithium chloride is used as raw material to prepare battery-grade lithium carbonate by sodium carbonate precipitation (Li Liangbin, Hu Naigen, Huang Xuewu, Ge Niuwei, Zhu Shigui, Xiong Xunman, Ma Zhenqian, a lithium chloride solution is used to prepare battery-grade carbonic acid Methods of Lithium, CN101609888; Ma Jin, Ma Aijun, Xu Zhongji, He Guocai, Yi Chao, Lu Xingwu, Cheng Liang, Li Yuliang, Ji Wuren, Gong Dalei, Shao Chuanbing, Li Shourong, Zhang Enyu, Li Yu, Xue Yingying, a The preparation process of battery-grade lithium carbonate, CN103351010A), the disadvantage of this method is that the purity of the raw materials is very high, and the raw materials containing lithium carbonate cannot be processed.

In short, in the preparation of battery-grade lithium carbonate, the above patents all use sodium carbonate (soda ash) as a precipitant. However, the use of sodium carbonate as a precipitant has problems such as too wide particle size distribution (see Figure 1), and there is often a certain gap with the quality requirements of battery-grade lithium carbonate. In addition, the mother liquor obtained after producing lithium carbonate with sodium carbonate as a precipitant contains high concentration of sodium chloride, which has little recovery value (Qinghai Salt Lake has abundant high-quality sodium chloride resources), and returning to the salt lake will affect the elements of the salt lake Balance is not conducive to the sustainable development of Salt Lake enterprises.

3. Contents of the invention

In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a kind of method with potassium carbonate as precipitant to prepare battery-grade lithium carbonate, it is characterized in that: it has the following steps to complete, lye preparation→impurity removal→ion exchange→evaporation Concentration→reaction aging→filtering and washing→drying→finished product; the process steps of the lye preparation process: preparing a potassium hydroxide solution with a mass percentage of 10-35%, preparing a potassium carbonate solution with a concentration of 1-3mol/L, and pressing The mass ratio of potassium hydroxide: potassium carbonate is 10~50:1 and the two solutions are mixed for later use;

The process steps of the impurity removal process: take the salt lake brine and put it in the reactor, add potassium hydroxide and potassium carbonate mixed solution, adjust the pH of the salt lake brine to 10~14, and stir at a stirring speed of 10~200 rpm. 0.5~3h, the reaction temperature of the solution is kept at 10~90°C, the magnesium ions in the brine of the salt lake react with potassium hydroxide to form magnesium hydroxide precipitates, and the calcium ions react with potassium carbonate to form calcium carbonate precipitates, and the magnesium hydroxide and carbonate The calcium precipitate is separated from the lithium chloride, and the lithium chloride solution is used for standby;

The process steps of the ion exchange process: the spare lithium chloride solution is continuously passed through an ion exchange column filled with a cation exchange resin to obtain a refined lithium chloride solution for standby use;

The process steps of the evaporation and concentration process: evaporate and concentrate the refined lithium chloride solution, control the concentration of lithium ions at 1.5~3.5mol/L, evaporate and concentrate the lithium chloride solution, and cool it for later use;

The process steps of the reaction aging process: adding lithium carbonate seed crystals to the spare lithium chloride solution, the amount of lithium carbonate seed crystals added is 1.0-30g per liter of lithium chloride solution, and then slowly added at a concentration of 1-3mol/L Potassium carbonate solution, the feeding rate of potassium carbonate is 1mL/min~200mL/min, the reaction temperature is controlled at 10℃~95℃, the stirring speed is controlled at 100rpm~1000rpm, and the ultrasonic wave is turned on while adding potassium carbonate solution. Device, ultrasonic power 5w~2000w/L solution, ultrasonic frequency 50KHZ~1MHZ, ultrasonic time 0~2h;

After potassium carbonate solution feeding is finished, carry out the aging of lithium carbonate crystal, aging time 0～2h; The lithium carbonate suspension is standby after aging;

The process steps of the filtering and washing process: filter the above-mentioned aged lithium carbonate suspension with medium-speed filter paper at room temperature, and wash the filter cake obtained by filtering with 70°C-90°C deionized water for more than 3 times for standby;

The technical steps of the drying process: drying the above spare filter cake in an oven, the drying temperature is 50°C-120°C, and the drying time is 4h-16h, and the battery-grade lithium carbonate product is obtained after drying. When storing finished battery grade lithium carbonate products, care should be taken to avoid direct sunlight and storage under high humidity conditions.

The beneficial effect of the present invention is: the present invention uses potassium carbonate as precipitating agent and lithium chloride reaction to prepare lithium carbonate, and the mother liquor obtained at last is potassium chloride solution with higher purity, and this mother liquor can be directly used to produce potassium chloride or carbonate Potassium, no waste generation; the more serious wall sticking problem in the reaction process is solved by adding seed crystals and the reaction temperature; the combination of seed crystals, reaction temperature, stirring speed, and ultrasound avoids the influence of lithium carbonate crystal aggregation and wide particle size distribution The quality of battery grade lithium carbonate products. The lithium carbonate crystal morphology that obtains under this condition is better, and product quality is stable.

4. Attached drawings

Figure 1 is the particle size distribution of lithium carbonate using sodium carbonate as precipitant (without ultrasound)

Figure 2 is the particle size distribution of lithium carbonate using potassium carbonate as precipitant (without ultrasound)

Figure 3 is the SEM image of lithium carbonate crystals prepared by conventional methods (without ultrasound)

Figure 4 is the SEM image of lithium carbonate crystals prepared by this method (with ultrasound)

5. Specific implementation

Case 1

Take 1000mL lithium chloride solution, which contains lithium ions 2.16 mol/L, magnesium ions 0.09 mol/L, calcium ions 0.012 mol/L, potassium ions 0.076 mol, sodium ions 0.26 mol/L, add 30% hydrogen The pH of the potassium oxide solution was adjusted to 12, the temperature was controlled at 70°C, the stirring speed was 100 rpm, and the reaction time was 2 hours. After filtration, a lithium chloride solution was obtained for separating magnesium ions and calcium ions. The lithium chloride solution is filled with D751 chelating ion exchange resin, and the absorbed lithium chloride solution is concentrated, and the final lithium ion content is 3.01mol/L. Take 350 mL of LiCl solution and add it to a 1000 mL reaction kettle, add 2 g of lithium carbonate seed crystals, and then add 1.5 mol/L potassium carbonate solution, the feeding speed is 10 mL/min, the reaction temperature is 90 ° C, and the stirring speed is 300 rpm. Turn on the ultrasonic device, ultrasonic power 1000w solution, ultrasonic time 35min. After the addition of the potassium carbonate solution was completed, the lithium carbonate crystals were aged for 1 h. Then the lithium carbonate suspension was filtered and washed 3 times with pure water. Finally, dry at 70°C.

Case 2

Take 1000mL lithium chloride solution, which contains lithium ions 2.16 mol/L, magnesium ions 0.09 mol/L, calcium ions 0.012 mol/L, potassium ions 0.076 mol, sodium ions 0.26 mol/L, add 30% hydrogen The pH of the potassium oxide solution was adjusted to 11, the temperature was controlled at 70° C., the reaction time was 2 hours, and the stirring speed was 200 rpm. After filtration, a lithium chloride solution for separating magnesium ions was obtained. The lithium chloride solution is filled with D751 chelating ion exchange resin, and the absorbed lithium chloride solution is concentrated, and the final lithium ion content is 3.01mol/L. Take 350 mL of LiCl solution and add it to a 1000 mL reaction kettle, add 2 g of lithium carbonate seed crystals, and then add 1.5 mol/L potassium carbonate solution, the feeding speed is 10 mL/min, the reaction temperature is 80 ° C, and the stirring speed is 400 rpm. Turn on the ultrasonic device, the ultrasonic power is 800w solution, and the ultrasonic time is 35min. After the addition of the potassium carbonate solution was completed, the lithium carbonate crystals were aged for 1 h. Then the lithium carbonate suspension was filtered and washed 3 times with pure water. Finally, dry at 70°C.

Case 3

Take 1000mL lithium chloride solution, which contains lithium ions 2.16 mol/L, magnesium ions 0.09 mol/L, calcium ions 0.012 mol/L, potassium ions 0.076 mol, sodium ions 0.26 mol/L, add 30% hydrogen The pH of the potassium oxide solution was adjusted to 11, the temperature was controlled at 70° C., the reaction time was 2 hours, and the stirring speed was 200 rpm. After filtration, a lithium chloride solution for separating magnesium ions was obtained. The lithium chloride solution is filled with D751 chelating ion exchange resin, and the absorbed lithium chloride solution is concentrated, and the final lithium ion content is 3.01mol/L. Take 350 mL of LiCl solution and add it to a 1000 mL reaction kettle, add 3 g of lithium carbonate seed crystals, and then add 1.5 mol/L potassium carbonate solution, the feeding speed is 20 mL/min, the reaction temperature is 80 ° C, and the stirring speed is 400 rpm. Turn on the ultrasonic device, ultrasonic power 800w solution, ultrasonic time 25min. After the addition of the potassium carbonate solution was completed, the lithium carbonate crystals were aged for 2 hours. Then the lithium carbonate suspension was filtered and washed 3 times with pure water. Finally, dry at 70°C.

Rights request:

(1) The magnesium ions and calcium ions in the lithium chloride solution are removed by reactive precipitation of potassium hydroxide and potassium carbonate, and the ratio of potassium hydroxide and potassium carbonate is 10~50:1 by mass.

(2) Add potassium hydroxide solution to the lithium chloride solution to adjust the pH to 10~14, react at 10°C~90°C for 0.5~3h, stir at 10~200 rpm, adjust the pH to 11, and control the temperature 70°C, reaction time 2h.

(3) Potassium carbonate is used as the precipitating agent for the lithium chloride solution, and the concentration of potassium carbonate is controlled at 1mol/L~3mol/L.

(4) Lithium carbonate seed crystals are added to the lithium chloride solution, and the amount of seed crystals added is 1.0~30g/L lithium chloride solution.

(5) The feeding rate of potassium carbonate solution is 1mL/min~200mL/min, the reaction temperature is controlled at 10℃~95℃, and the stirring speed is controlled at 100rpm~1000rpm.

(6) Turn on the ultrasonic device while adding the potassium carbonate solution, the ultrasonic power is 5w~2000w/L solution, the ultrasonic frequency is 50KHZ~1MHZ, and the ultrasonic time is 0~2h.

(7) After the potassium carbonate solution is fed, the lithium carbonate crystals are aged for 0-2 hours.

Claims (1)

1. the method preparing battery-level lithium carbonate for precipitant with potassium carbonate, it is characterised in that: it has following steps to complete, Alkali liquid compounding → remove impurity → ion exchange → evaporation and concentration → reaction aging → filtration washing → be dried → finished product；Alkali liquid compounding work The processing step of sequence: preparation mass percent is the potassium hydroxide solution of 10～35%, and compound concentration is the carbonic acid of 1～3mol/L Potassium solution, and potassium hydroxide in mass ratio: potassium carbonate is that 10 ~ 50:1 is by two kinds of solution mixing for standby use；

The processing step of remove impurity operation: take salt lake bittern and be placed in reactor and add potassium hydroxide and potassium carbonate mixed solution, The PH of salt lake bittern is adjusted to 10 ~ 14, and stirs, 10 ~ 200 turns/min of mixing speed, react 0.5 ~ 3h, solution reaction temperature is protected Holding at 10～90 DEG C, the magnesium ion in salt lake bittern and potassium hydroxide react generation magnesium hydrate precipitate, calcium ion and potassium carbonate Reaction generates precipitation of calcium carbonate, is separated with lithium chloride with precipitation of calcium carbonate by magnesium hydroxide by filtering, and lithium chloride solution is standby；

The processing step of ion-exchange process: standby lithium chloride solution is continued through the ion being filled with cation exchange resin Exchange column, the lithium chloride solution obtaining refining is standby；

The processing step of evaporation and concentration operation: the lithium chloride solution evaporation and concentration after refining, the concentration of lithium ion controls 1.5 ~ 3.5mol/L, the cooling of lithium chloride solution evaporation and concentration is standby；

The processing step of reaction aging operation: add lithium carbonate crystal seed, lithium carbonate Seed charge at standby lithium chloride solution For adding 1.0～30g in every liter of lithium chloride solution, being then slowly added into the solution of potassium carbonate that concentration is 1～3mol/L, potassium carbonate adds Material speed 1mL/min～200mL/min, reaction temperature controls at 10 DEG C～95 DEG C, speed of agitator control 100 turns/min ~ 1000 turns/min, while adding solution of potassium carbonate, open Vltrasonic device, ultrasonic power 5w～2000w/L solution, supersonic frequency Rate 50KHZ～1MHZ, ultrasonic time 0～2h；

After solution of potassium carbonate has fed, carry out the ageing of lithium carbonate crystal, digestion time 0 ~ 2h；After the ageing of lithium carbonate suspension Standby；

The processing step of filter and cleaning process: lithium carbonate suspension standby for above-mentioned ageing is at room temperature used Medium speed filter paper mistake Filter, the filter cake being filtrated to get is standby with 70 DEG C～90 DEG C of deionized water wash more than 3 times；

The processing step of drying process: baking temperature is 50 DEG C～120 DEG C, and drying time is 4h～16h, obtains electricity after being dried Pond level lithium carbonate finished product, battery-level lithium carbonate finished product stores it should be noted that avoid direct sunlight, avoid storing under conditions of high humidity.