Method for preparing lithium hydroxide from lithium salt

Abstract

The invention relates to the technical field of lithium hydroxide preparation, in particular to a method for preparing lithium hydroxide from lithium salt, which comprises the following steps: mixing lithium carbonate, quicklime and water into slurry; putting the slurry into a reactor for heating and stirring, and obtaining lithium hydroxide slurry after the reaction is finished; filtering and separating the lithium hydroxide slurry to obtain causticized calcium carbonate filter residues and lithium hydroxide mother liquor; evaporating, crystallizing and drying the lithium hydroxide mother liquor to obtain a lithium hydroxide product; calcining and decomposing the calcium carbonate filter residues to obtain quick lime, and recycling the quick lime. The method for preparing the lithium hydroxide from the lithium salt is simple in technological process, the materials can be recycled, the utilization rate of the materials is effectively increased, the cost is saved, and in addition, the yield of the lithium hydroxide can be effectively increased and the impurity content can be effectively reduced by controlling the proportion and the concentration of the raw materials and various parameters in the reaction process.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium hydroxide preparation, in particular to a method for preparing lithium hydroxide from a lithium salt. Background Art

[0002] Currently, the main method for producing lithium hydroxide is the fire refining method. This involves mixing spodumene concentrate (generally containing 6% lithium oxide) with limestone, grinding it, and sintering it at 1150-1250°C to produce lithium aluminate and calcium silicate. The mixture is then wet-milled and pulverized, and the lithium hydroxide is leached with a washing solution. The solution is then filtered and evaporated to form a finished product of lithium hydroxide monohydrate. The industrial lithium hydroxide is then dissolved in cold water with stirring, and the insoluble matter is filtered off. The filtrate is heated and evaporated until crystals appear, cooled, and dried to produce a lithium hydroxide monohydrate reagent. Anhydrous lithium hydroxide can be obtained by drying lithium hydroxide monohydrate in a desiccator filled with phosphorus pentoxide for several days. Alternatively, lithium hydroxide monohydrate can be produced by slowly heating the lithium hydroxide monohydrate to 140°C in a hydrogen stream for dehydration. This method not only has the characteristics of a long process, multiple equipment, and high energy consumption, but also has high production costs, making it unsuitable for industrial production.

[0003] To this end, the present invention proposes a method for preparing lithium hydroxide from a lithium salt to achieve improvements on the above-mentioned problems. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing lithium hydroxide from lithium salts, so as to solve the problems mentioned in the above background technology that the existing fire refining method for preparing lithium hydroxide has the characteristics of long process, multiple equipment, high consumption, high production cost, and is not conducive to industrial production.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing lithium hydroxide from a lithium salt, comprising the following steps:

[0006] S1. Mix lithium carbonate, quicklime and water into slurry.

[0007] S2, adding the slurry to a reactor for heating and stirring, and completing the reaction to obtain lithium hydroxide slurry;

[0008] S3, filtering and separating the lithium hydroxide slurry to obtain causticized calcium carbonate filter residue and lithium hydroxide mother liquor;

[0009] S4, evaporating, crystallizing and drying the lithium hydroxide mother liquor to obtain a lithium hydroxide product;

[0010] S5. Calcining and decomposing the calcium carbonate filter residue to obtain quicklime, which is recycled again.

[0011] The present invention is further configured such that the mass ratio of the lithium carbonate to quicklime is 1:1.5-1.8, and the solid-liquid ratio of the slurry is 1:8.

[0012] The present invention is further configured such that the reaction temperature of the reactor is 85-110°C.

[0013] The present invention is further configured such that the slurry is stirred in the reactor for 4-5 hours at a stirring speed of 350-500 rpm.

[0014] The present invention also provides lithium hydroxide prepared by the method.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The method for preparing lithium hydroxide from lithium salts proposed in the present invention has a simple process flow, and the materials can be recycled, effectively improving the utilization rate of materials and saving costs. In addition, by controlling the ratio and concentration of raw materials and various parameters during the reaction process, the yield of lithium hydroxide can be effectively increased and the impurity content can be reduced.

[0017] Specifically, lithium carbonate, quicklime, and water are mixed into a slurry. The slurry is placed in a reactor and heated and stirred until the reaction is complete to obtain lithium hydroxide slurry. The lithium hydroxide slurry is filtered and separated to obtain causticized calcium carbonate residue and lithium hydroxide mother liquor. The lithium hydroxide mother liquor is evaporated, crystallized, and dried to obtain a lithium hydroxide product. The calcium carbonate residue is calcined and decomposed to obtain quicklime, which is recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0020] Example

[0021] See also Figure 1 , in the figure: This embodiment is a preferred embodiment of the present technical solution, a method for preparing lithium hydroxide from a lithium salt, comprising the following steps:

[0022] S1. Mix lithium carbonate, quicklime and water into slurry.

[0023] S2, adding the slurry to a reactor for heating and stirring, and completing the reaction to obtain lithium hydroxide slurry;

[0024] S3, filtering and separating the lithium hydroxide slurry to obtain causticized calcium carbonate filter residue and lithium hydroxide mother liquor;

[0025] S4, evaporating, crystallizing and drying the lithium hydroxide mother liquor to obtain a lithium hydroxide product;

[0026] S5. Calcining and decomposing the calcium carbonate filter residue to obtain quicklime, which is recycled again.

[0027] The mass ratio of lithium carbonate to quicklime is 1:1.5-1.8, the solid-liquid ratio of the slurry is 1:8, the reaction temperature of the reactor is 85-110°C, the stirring time of the slurry in the reactor is 4-5 hours, and the stirring speed is 350-500rpm.

[0028] In the above method, lithium carbonate, quicklime, and water are first subjected to a causticization reaction in a lithium carbonate to quicklime mass ratio of 1:1.5-1.8 and a solid-liquid ratio of 1:8 to obtain a lithium hydroxide slurry. In the causticization reaction, the reaction temperature of the reactor is 85-110°C, and the slurry is stirred in the reactor for 4-5 hours at a stirring speed of 350-500 rpm. The reaction temperature of the reactor is 85-110°C, and the slurry is stirred in the reactor for 4-5 hours at a stirring speed of 350-500 rpm. The lithium hydroxide slurry after the reaction is separated by filtration to obtain a causticized calcium carbonate filter residue and a lithium hydroxide mother liquor. The lithium hydroxide mother liquor is evaporated, crystallized, and dried to obtain a lithium hydroxide product, and the filtered calcium carbonate filter residue is calcined and decomposed to obtain quicklime, which is recycled again. Lithium hydroxide is prepared in the above manner, has a simple process flow, and the materials can be recycled, effectively improving the utilization rate of the materials and saving costs. In addition, by controlling the raw material ratio, concentration, and various parameters during the reaction, the yield of lithium hydroxide can be effectively improved and the impurity content can be reduced.

[0029] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0030] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing lithium hydroxide from a lithium salt, characterized in that: The following steps are involved: S1. Mix lithium carbonate, quicklime and water into slurry. S2, adding the slurry to a reactor for heating and stirring, and completing the reaction to obtain lithium hydroxide slurry; S3, filtering and separating the lithium hydroxide slurry to obtain causticized calcium carbonate filter residue and lithium hydroxide mother liquor; S4, evaporating, crystallizing and drying the lithium hydroxide mother liquor to obtain a lithium hydroxide product; S5. Calcining and decomposing the calcium carbonate filter residue to obtain quicklime, which is recycled again.

2. The method for preparing lithium hydroxide from a lithium salt according to claim 1, wherein: The mass ratio of the lithium carbonate to quicklime is 1:1.5-1.8, and the solid-liquid ratio of the slurry is 1:

8.

3. The method for preparing lithium hydroxide from a lithium salt according to claim 1, wherein: The reaction temperature of the reactor is 85-110°C.

4. The method for preparing lithium hydroxide from a lithium salt according to claim 1, wherein: The slurry is stirred in the reactor for 4-5 hours at a stirring speed of 350-500 rpm.

5. prepare lithium hydroxide according to the method described in claim 1.

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