阅读说明：本技术 一种高效连续电子级氟化锂生产工艺 (Efficient continuous electronic-grade lithium fluoride production process ) 是由 徐铭 王志鹏 段志强 康文鹏 胡伟伟 陈虎 栾紫翔 周川 于 2020-03-27 设计创作，主要内容包括：本发明提供了一种高效连续电子级氟化锂生产工艺,包括以下步骤：(1)碳化过滤；(2)离子交换；(3)重结晶；(4)高纯碳化；(5)合成；(6)干燥；(7)冷却包装。本发明生产工艺有效降低了产品中杂质的含量,保证了氟化锂产品的品质；提升了氟化锂的产能,满足六氟磷酸锂生产原料指标与原料供应,同时降低了生产的人工成本；工艺过程为循环体系,原料利用率高,并且环保。(The invention provides a high-efficiency continuous electronic-grade lithium fluoride production process, which comprises the following steps: (1) carbonizing and filtering; (2) ion exchange; (3) recrystallizing; (4) carbonizing at high purity; (5) synthesizing; (6) drying; (7) and (6) cooling and packaging. The production process effectively reduces the content of impurities in the product and ensures the quality of the lithium fluoride product; the productivity of lithium fluoride is improved, the raw material indexes and raw material supply of lithium hexafluorophosphate production are met, and the labor cost of production is reduced; the process is a circulating system, the utilization rate of raw materials is high, and the environment is protected.)

1. A high-efficiency continuous electronic-grade lithium fluoride production process is characterized by comprising the following steps:

(1) carbonizing and filtering: adding industrial-grade lithium carbonate into a carbonization kettle filled with ultrapure water, mixing to prepare lithium carbonate slurry, introducing carbon dioxide into the lithium carbonate slurry for reaction, obtaining a lithium bicarbonate solution after the reaction is completed, and filtering to obtain a pure lithium bicarbonate solution;

(2) ion exchange: pumping the pure lithium bicarbonate solution obtained in the step (1) into an ion exchange system to remove cations such as calcium, magnesium and the like in the lithium bicarbonate solution;

(3) and (3) recrystallization: pumping the lithium bicarbonate solution with the cations removed in the step (2) into a reaction kettle for recrystallization, crystallizing a lithium bicarbonate liquid by adopting a steam coil heating mode to generate a lithium carbonate solid, filtering residues by a vibrating screen, centrifuging to obtain a high-purity lithium carbonate ointment, cooling the lithium carbonate mother liquor generated after centrifuging by two stages of cooling circulating water, and refluxing to the carbonization stage in the step (1) for recycling;

(4) high-purity carbonization: conveying the high-purity lithium carbonate ointment obtained in the step (3) to a high-purity carbonization tank filled with ultrapure water, mixing to obtain lithium carbonate slurry, introducing carbon dioxide for carbonization, converting lithium carbonate into lithium bicarbonate, filtering, and cooling to obtain a high-purity lithium bicarbonate solution;

(5) synthesizing: pumping the high-purity lithium bicarbonate solution obtained in the step (4) into a synthesis kettle, simultaneously adding aqueous hydrofluoric acid for reaction to obtain lithium fluoride slurry after the reaction is finished, filtering and washing to obtain high-purity lithium fluoride ointment, and refluxing lithium fluoride mother liquor generated by filtering for high-purity carbonization;

(6) and (3) drying: heating and drying the lithium fluoride ointment generated in the step (5) by using steam by using a vacuum dryer to obtain dried lithium fluoride;

(7) cooling and packaging: and (4) cooling the lithium fluoride dried in the step (6) in a cooler, screening, discharging and packaging to obtain the electronic-grade lithium fluoride product.

2. The efficient continuous electronic-grade lithium fluoride production process according to claim 1, wherein in the step (1), the lithium carbonate slurry ratio is 25: 1-35: 1, the carbon dioxide introducing speed is 10-60 Nm/h, the reaction temperature is 25-35 ℃, and the reaction time is 1.5-2.5 h.

3. The efficient continuous electronic-grade lithium fluoride production process according to claim 1, wherein in the step (2), the pumping speed of the lithium bicarbonate solution is 10-15 m for carrying out dry distillation/h; the content of calcium, magnesium and other ions after ion exchange is 0.02-0.2 ppm.

4. The efficient continuous electronic-grade lithium fluoride production process according to claim 1, wherein in the step (3), the pumping speed of the lithium bicarbonate solution is 10-15 m for each year, the recrystallization temperature is 70-100 ℃, and the recrystallization time is 1.5-2 hours.

5. The efficient continuous electronic-grade lithium fluoride production process according to claim 1, wherein in the step (3), the lithium carbonate mother liquor concentration is 9.5-13.5 g/L, and the temperature of the lithium carbonate mother liquor after cooling is 20-35 ℃.

6. The efficient continuous electronic-grade lithium fluoride production process according to claim 1, wherein in the step (4), the lithium carbonate slurry ratio is 25: 1-35: 1, the carbon dioxide introducing speed is 10-60 Nm/h, the carbonization temperature is 25-35 ℃, and the carbonization time is 2.5-3.5 h.

7. The efficient continuous electronic-grade lithium fluoride production process according to claim 1, wherein in the step (5), the mass percent of the aqueous hydrofluoric acid is 30-40%, the reaction temperature is 40-50 ℃, the reaction time is 2.5-3.5 h, the adding speed of the high-purity lithium bicarbonate solution is 6-10 m/h, the adding speed of the aqueous hydrofluoric acid is 250-300L/h, and the pH at the synthesis end is 2-6.

8. The high-efficiency continuous electronic-grade lithium fluoride production process according to claim 1, wherein in the step (6), the drying is to dry the lithium fluoride to the moisture content of less than 100ppm, and the drying time is controlled to be 8-12 h.

Technical Field

The invention relates to a production process of chemical products, in particular to a high-efficiency continuous electronic-grade lithium fluoride production process.

Background

Lithium hexafluorophosphate is currently the most predominant electrolyte lithium salt used in commercial lithium ion batteries, and no electrolyte has been found to completely replace lithium hexafluorophosphate, and is expected to remain the only electrolyte salt used on a large scale in the next decade. The research work of lithium batteries in China is carried out later, most of the work is concentrated on the preparation of electrode materials and the research of battery systems, and few reports are made on the research work of the preparation of electrolyte materials such as lithium hexafluorophosphate and the like. Only a few domestic companies can prepare a small amount of lithium hexafluorophosphate, the process has the defects of high equipment requirement, high acid value of the product, unstable quality and the like, and the quality is still far from the foreign countries. Lithium hexafluorophosphate required by lithium battery production in China basically depends on import.

The battery grade lithium fluoride is one of necessary raw materials for producing the commonly used electrolyte lithium hexafluorophosphate of the lithium ion battery. Lithium fluoride produced by the conventional lithium fluoride production process is used as a raw material for preparing electrolyte lithium hexafluorophosphate, the production requirements of lithium hexafluorophosphate on quality and yield cannot be met, the production requirements of lithium fluoride on the environment are high, the production environment is a dust-free environment, and in the conventional lithium fluoride production, on one hand, the factors of human intervention are large, so that the produced product often has high impurity contents such as silicon, calcium, magnesium, sulfate radical and the like, and the raw material indexes of lithium hexafluorophosphate production cannot be met. On the other hand, due to the improvement of the productivity of lithium hexafluorophosphate, the productivity of lithium fluoride can not meet the production requirement of lithium hexafluorophosphate.

Disclosure of Invention

In view of the above technical problems, the present invention aims to provide a high-efficiency continuous production process of electronic-grade lithium fluoride.

The invention relates to a high-efficiency continuous electronic-grade lithium fluoride production process, which comprises the following steps:

(1) carbonizing and filtering: adding industrial-grade lithium carbonate into a carbonization kettle filled with ultrapure water, mixing to prepare lithium carbonate slurry, introducing carbon dioxide into the lithium carbonate slurry for reaction, obtaining a lithium bicarbonate solution after the reaction is completed, and filtering to obtain a pure lithium bicarbonate solution;

(2) ion exchange: pumping the pure lithium bicarbonate solution obtained in the step (1) into an ion exchange system to remove cations such as calcium, magnesium and the like in the lithium bicarbonate solution;

(3) and (3) recrystallization: pumping the lithium bicarbonate solution with the cations removed in the step (2) into a reaction kettle for recrystallization, crystallizing a lithium bicarbonate liquid by adopting a steam coil heating mode to generate a lithium carbonate solid, filtering residues by a vibrating screen, centrifuging to obtain a high-purity lithium carbonate ointment, cooling the lithium carbonate mother liquor generated after centrifuging by two stages of cooling circulating water, and refluxing to the carbonization stage in the step (1) for recycling;

(4) high-purity carbonization: conveying the high-purity lithium carbonate ointment obtained in the step (3) to a high-purity carbonization tank filled with ultrapure water, mixing to obtain lithium carbonate slurry, introducing carbon dioxide for carbonization, converting lithium carbonate into lithium bicarbonate, filtering, and cooling to obtain a high-purity lithium bicarbonate solution;

(5) synthesizing: pumping the high-purity lithium bicarbonate solution obtained in the step (4) into a synthesis kettle, simultaneously adding aqueous hydrofluoric acid for reaction to obtain lithium fluoride slurry after the reaction is finished, filtering and washing to obtain high-purity lithium fluoride ointment, and refluxing lithium fluoride mother liquor generated by filtering for high-purity carbonization;

(6) and (3) drying: heating and drying the lithium fluoride ointment generated in the step (5) by using steam by using a vacuum dryer to obtain dried lithium fluoride;

(7) cooling and packaging: and (4) cooling the lithium fluoride dried in the step (6) in a cooler, screening, discharging and packaging to obtain the electronic-grade lithium fluoride product.

Further, in the step (1), the ratio of the lithium carbonate slurry is 25: 1-35: 1, the carbon dioxide introduction speed is 10-60 Nm/h, the reaction temperature is 25-35 ℃, and the reaction time is 1.5-2.5 h.

Further, in the step (2), pumping the lithium bicarbonate solution into the high-speed dry bottom high-; the content of calcium, magnesium and other ions after ion exchange is 0.02-0.2 ppm.

Further, in the step (3), the pumping speed of the lithium bicarbonate solution is 10-15 m for carrying out the dry distillation/h, the recrystallization temperature is 70-100 ℃, and the recrystallization time is 1.5-2 h;

further, in the step (3), the concentration of the lithium carbonate mother liquor is 9.5-13.5 g/L, and the temperature of the lithium carbonate mother liquor after cooling is 20-35 ℃.

Further, in the step (4), the ratio of the lithium carbonate slurry is 25: 1-35: 1, the carbon dioxide introduction speed is 10-60 Nm year/h, the carbonization temperature is 25-35 ℃, and the carbonization time is 2.5-3.5 h.

Further, in the step (5), the mass percent of the hydrofluoric acid with water is 30-40%, the reaction temperature is 40-50 ℃, the reaction time is 2.5-3.5 hours, the adding speed of the high-purity lithium bicarbonate solution is 6-10 m/h, the adding speed of the hydrofluoric acid with water is 250-300L/h, and the pH at the synthesis end point is controlled to be 2-6.

Further, in the step (6), the drying is to dry the lithium fluoride to the moisture content of less than 100ppm, and the drying time is controlled to be 8-12 h.

The invention has the following effects:

1. the impurity elements are main factors influencing the quality of lithium hexafluorophosphate products, in the process, an ion exchange system removes cations such as calcium, magnesium and the like in process liquid lithium bicarbonate, the impurity content is reduced in the primary stage of the process, a recrystallization system separates impurities such as silicon, sulfate radicals, chloride ions and the like in the process liquid lithium bicarbonate through heating and evaporation, and simultaneously liquid materials are converted into solid materials, so that the quality of the lithium fluoride products is ensured.

2. The process breaks through the traditional intermittent monomer production process, all systems are connected to form a continuous production process, the intermittent time of monomer production is avoided, and the production yield is greatly improved through the continuity of the process. In addition, the process can avoid the influence of human intervention on the product quality in the process of producing the lithium fluoride, reduce the impurity content, further improve the productivity of the lithium fluoride, meet the raw material indexes and raw material supply of lithium hexafluorophosphate production, and simultaneously reduce the labor cost of production.

3. The lithium carbonate mother liquor and the lithium fluoride mother liquor in the process are recycled, the water consumption is reduced, the discharge of the standard wastewater of the process is reduced, and the process does not generate industrial waste gas and waste residue and is beneficial to environmental protection.

Drawings

FIG. 1 is a flow chart of the production process of the present invention.

Detailed Description

The production process of the present invention is further illustrated by the following specific examples.