阅读说明：本技术 一种采用锂辉石制备单水硫酸锂的方法 (Method for preparing lithium sulfate monohydrate by using spodumene ) 是由 李良彬 艾刚华 肖娇 郁兴国 高贵彦 周峰 卢敏 邢静波 熊得浩 宁朋 何文琪 于 2021-09-06 设计创作，主要内容包括：本发明提供一种采用锂辉石制备单水硫酸锂的方法。采用锂辉石制备单水硫酸锂的方法,制备方法包含以下步骤：步骤S1：锂辉石由硫酸法提锂制备硫酸锂粗液；步骤S2：对所述硫酸锂粗液进行除杂处理,除去溶液中的杂质离子得到硫酸锂净化液；步骤S3：取所述硫酸锂净化液蒸发浓缩,冷却结晶,过滤得到硫酸锂湿料；步骤S4：淋洗所述硫酸锂湿料,干燥得到单水硫酸锂产品。采用锂辉石制备单水硫酸锂的方法制备得到的单水硫酸锂纯度高,满足Li-(2)SO-(4)·H-(2)O≥99%,Na≤0.03%,K≤0.04%,工艺简单,成本较低,得到的产品杂质少。(The invention provides a method for preparing lithium sulfate monohydrate by using spodumene. The method for preparing the lithium sulfate monohydrate by adopting the spodumene comprises the following steps: step S1: extracting lithium from spodumene by a sulfuric acid method to prepare a crude lithium sulfate solution; step S2: removing impurities from the crude lithium sulfate solution to remove impurity ions in the solution to obtain purified lithium sulfate solution; step S3: evaporating and concentrating the lithium sulfate purified solution, cooling, crystallizing and filtering to obtain a lithium sulfate wet material; step S4: and leaching the wet lithium sulfate material, and drying to obtain a lithium sulfate monohydrate product. The lithium sulfate monohydrate prepared by the method for preparing the lithium sulfate monohydrate by using spodumene has high purity, and meets the requirement of Li 2 SO 4 ·H 2 More than or equal to 99 percent of O, less than or equal to 0.03 percent of Na and less than or equal to 0.04 percent of K, simple process, lower cost and less impurities of the obtained product.)

1. A method for preparing lithium sulfate monohydrate by using spodumene is characterized by comprising the following steps:

step S1: extracting lithium from spodumene by a sulfuric acid method to prepare a crude lithium sulfate solution;

step S2: removing impurities from the crude lithium sulfate solution to remove impurity ions in the solution to obtain purified lithium sulfate solution;

step S3: evaporating and concentrating the lithium sulfate purified solution, cooling, crystallizing and filtering to obtain a lithium sulfate wet material;

step S4: and leaching the wet lithium sulfate material, and drying to obtain a lithium sulfate monohydrate product.

2. The method for preparing lithium sulfate monohydrate with spodumene according to claim 1, wherein the impurity removal treatment of the step S2 comprises chemical precipitation impurity removal for removing Mg and Si impurity ions and resin adsorption impurity removal for removing Ca, K and Na ions.

3. The method for preparing lithium sulfate monohydrate using spodumene according to claim 2, wherein said step S2 is implemented to control the impurity content of the solution after impurity removal to be Na less than or equal to 1g/L, K less than or equal to 0.3g/L, Ca less than or equal to 0.005g/L, Mg less than or equal to 0.005g/L and Si less than or equal to 0.003 g/L.

4. The method for preparing lithium sulfate monohydrate using spodumene according to claim 3, wherein the purified solution of lithium sulfate in step S3 is evaporated and concentrated 3-6 times.

5. The method for preparing lithium sulfate monohydrate using spodumene according to claim 4, wherein the evaporation manner in step S3 is flash evaporation, the temperature is 95-100 ℃, and the pressure is 350-450 mmhg.

6. The method for preparing lithium sulfate monohydrate by using spodumene according to claim 5, wherein the wet lithium sulfate material in the step S4 is washed by pure water with the mass 1-1.5 times that of the wet lithium sulfate material, or washed by water for multiple times in a gradient manner, so as to remove soluble impurities in the lithium sulfate.

Technical Field

The invention relates to a chemical production technology of lithium sulfate monohydrate, belongs to the field of extraction of lithium from ores, and particularly relates to a method for preparing lithium sulfate monohydrate by using spodumene.

Background

The lithium sulfate monohydrate is colorless monoclinic crystal, lithium sulfate monohydrate, colorless monoclinic crystal, each part of lithium sulfate monohydrate is dissolved in 2.6 parts of water, the solution is neutral and almost insoluble in 80% ethanol, acetone or pyridine, and the crystal water is lost when the solution is heated to 130 ℃. It is mainly used for analytical reagent, separation of calcium and magnesium, pharmaceutical industry and other fields, and also used for making fireworks. The dehydrated lithium sulfate monohydrate can still be used for preparing a high-conductivity solid electrode at high temperature, can be used as an ion conductor in a high-temperature hydrogen-oxygen battery, can be widely used as a high-temperature heat storage material, and can be used as one of the common reference substances for correcting a thermal analyzer. These are sufficient to represent the wide range of uses and the large demand for lithium sulfate monohydrate. Meanwhile, due to the influence of market factors, the prices of lithium carbonate and lithium hydroxide products are gradually reduced; the lithium sulfate monohydrate has good application prospect and considerable profit, so that the technical process for preparing the lithium sulfate monohydrate in a large scale in production is concerned.

The common preparation methods of the lithium sulfate monohydrate mainly comprise two methods, one method is to produce the lithium sulfate by taking brine as a raw material, the method has complex process and large medicament consumption, and the purity of the obtained lithium sulfate product is low; in another common method, lithium carbonate or lithium hydroxide is acidified by sulfuric acid, and a wet lithium sulfate material is obtained through evaporation concentration, cooling crystallization and centrifugal separation, and then dried to obtain lithium sulfate monohydrate. The method for directly preparing lithium sulfate by taking spodumene as a raw material has few literature reports and patents at home and abroad at present.

Disclosure of Invention

Based on the above, the invention provides a method for preparing lithium sulfate monohydrate by using spodumene, which has the advantages of short technological process, low cost and high product purity, and the lithium sulfate monohydrate obtained by the method meets the requirement of Li₂SO₄·H₂More than or equal to 99 percent of O, less than or equal to 0.05 percent of Na, less than or equal to 0.05 percent of K, less than or equal to 0.03 percent of Ca, less than or equal to 0.001 percent of Fe, less than or equal to 0.005 percent of Mg, less than or equal to 0.001 percent of Pb, less than or equal to 0.005 percent of Cl, and less than or equal to 0.01 percent of water-insoluble substances.

The invention provides a method for preparing lithium sulfate monohydrate by using spodumene, which comprises the following steps:

s1 extracting lithium: extracting lithium from spodumene by a sulfuric acid method to prepare a crude lithium sulfate solution;

s2 impurity removal: removing impurities from the lithium sulfate solution to remove impurity ions such as Na, K, Ca, Mg, Si and the like in the solution to obtain a lithium sulfate purified solution;

s3 evaporative crystallization: evaporating and concentrating the lithium sulfate purified solution, cooling and crystallizing, and filtering to obtain a lithium sulfate wet material;

s4 washing and drying: and leaching the wet lithium sulfate material, and drying to obtain a lithium sulfate monohydrate product.

Further, the impurity removal processing in step S2 includes chemical precipitation impurity removal and resin adsorption impurity removal, where the chemical precipitation impurity removal mainly removes impurity ions such as Mg and Si, and the resin adsorption removes ions such as Ca, K, and Na.

Furthermore, in the step S2, the impurity content of the solution after impurity removal is controlled to be less than or equal to 1g/L, less than or equal to 0.3g/L, less than or equal to 0.01g/L of Ca, less than or equal to 0.01g/L of Mg, and less than or equal to 0.006g/L of Si.

Further, in the step S3, the lithium sulfate purified solution is evaporated and concentrated by 3 to 6 times.

Furthermore, in the step S3, the evaporation manner is flash evaporation, the temperature is generally controlled to be 95-100 ℃, and the corresponding pressure is 350-450 mmhg.

Furthermore, in the step S4, soluble impurities in the lithium sulfate can be removed after the wet lithium sulfate is washed, and the wet lithium sulfate is usually washed once with pure water 1-1.5 times the mass of the wet lithium sulfate, or washed for multiple times in steps, so as to reduce the water consumption under the condition of ensuring the experimental effect.

Compared with other lithium salt preparation methods, the method for preparing lithium sulfate monohydrate by using spodumene has the following characteristics: the lithium sulfate monohydrate obtained by the method has high purity and meets the requirement of Li₂SO₄·H₂More than or equal to 99 percent of O, less than or equal to 0.03 percent of Na and less than or equal to 0.04 percent of K. Compared with the traditional preparation method of lithium sulfate monohydrate, namely a method for preparing the lithium sulfate monohydrate by acidifying lithium carbonate or lithium hydroxide with sulfuric acid, evaporating, concentrating, cooling, crystallizing, centrifugally separating and drying, the method has the advantages of simple process, low cost of reaction raw materials, low impurity content of products, continuous and large-scale production and great advantage.

Drawings

FIG. 1 is a process flow diagram of a method of preparing lithium sulfate monohydrate using spodumene in accordance with the present invention.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

The invention provides a method for preparing lithium sulfate monohydrate by using spodumene, which comprises the following steps:

step S1 extracting lithium: extracting lithium from spodumene by a sulfuric acid method to prepare a crude lithium sulfate solution;

step S2 impurity removal: removing impurities from the crude lithium sulfate solution to remove impurity ions such as Na, K, Ca, Mg, Si and the like in the solution to obtain purified lithium sulfate solution;

step S3 evaporative crystallization: evaporating and concentrating the lithium sulfate purified solution, cooling, crystallizing and filtering to obtain a lithium sulfate wet material;

step S4 washing and drying: and leaching the wet lithium sulfate material, and drying to obtain a lithium sulfate monohydrate product.

Further, the impurity removal processing of the step S2 includes chemical precipitation impurity removal for removing Mg and Si impurity ions and resin adsorption impurity removal for removing Ca, K, and Na ions.

Furthermore, in the step S2, the impurity content Na, K, Ca and Mg of the solution after impurity removal is controlled to be less than or equal to 1g/L, 0.3g/L, 0.005g/L and 0.003g/L respectively.

Further, in the step S3, the lithium sulfate purified solution is evaporated and concentrated by 3 to 6 times.

Further, the evaporation mode in the step S3 is flash evaporation, the temperature is 95-100 ℃, and the pressure is 350-450 mmhg.

Further, in the step S4, the wet lithium sulfate material is washed to remove soluble impurities in the lithium sulfate, and the washing manner of the wet lithium sulfate material is to wash the wet lithium sulfate material once with pure water 1-1.5 times the mass of the wet lithium sulfate material, or wash the wet lithium sulfate material for multiple times in a gradient manner, so as to reduce the water consumption under the condition of ensuring the experimental effect.

The method for preparing the lithium sulfate monohydrate by using the spodumene mainly comprises two stages, wherein the first stage is to convert the spodumene to prepare the lithium sulfate purified liquid with low impurity content, and the second stage is to prepare the lithium sulfate monohydrate product by using the lithium sulfate purified liquid. The staged embodiment example is as follows:

first stage conversion of spodumene to produce low impurity content Li₂SO₄The process of purifying the liquid is as follows: mixing RIM spodumene (Li)₂O: 6.12%) at 1000 deg.C for 30min, and transforming to obtain beta-spodumene. Adding 22% concentrated sulfuric acid according to the material-to-acid ratio, roasting at 250 deg.C for 40min, cooling, adding calcium carbonate, neutralizing, leaching and concentrating to obtain crude lithium sulfate solution, removing impurities by chemical precipitation and resin adsorption to obtain purified lithium sulfate solution (containing Li 20.32g/L, SO₄ ^2-：145.3 g/L，Ca：0.004g/L，Mg：0.002 g/L，Si：0.0016 g/L，Al：0.002 g/L。）

The second stage adopts the lithium sulfate purifying solution to prepare the lithium sulfate monohydrate by the following steps:

in one embodiment, 2L of the purified lithium sulfate solution is accurately measured in each 2L beaker, heated and concentrated 4 times, evaporated and concentrated, cooled and crystallized, filtered to obtain lithium sulfate crystals, then added with pure water, stirred and washed, then filtered, added with pure water for leaching to obtain a wet lithium sulfate material, and then placed in a drying oven for drying to obtain lithium sulfate monohydrate, which is labeled as example 1.

In one embodiment, a 5L beaker is taken, and 5L of the above purified lithium sulfate solution is accurately measured, heated and concentrated by 3 times, evaporated and concentrated, cooled and crystallized, filtered to obtain lithium sulfate crystals, then added with pure water, stirred and washed, then filtered, added with pure water for leaching to obtain a wet lithium sulfate material, and the wet lithium sulfate material is put into a drying oven for drying to obtain lithium sulfate monohydrate, which is labeled as example 2.

In one embodiment, a 5L beaker is taken, and 5L of the above purified lithium sulfate solution is accurately measured, heated and concentrated 4 times, evaporated and concentrated, cooled and crystallized, filtered to obtain lithium sulfate crystals, then pure water is added, stirred and washed, then filtered, added with pure water for leaching to obtain a wet lithium sulfate material, and the wet lithium sulfate material is put into a drying oven for drying to obtain lithium sulfate monohydrate, which is labeled as example 3.

In one embodiment, a 5L beaker is taken, and 5L of the above purified lithium sulfate solution is accurately measured, heated and concentrated by 6 times, evaporated and concentrated, cooled and crystallized, filtered to obtain lithium sulfate crystals, then added with pure water, stirred and washed, then filtered, added with pure water for leaching to obtain a wet lithium sulfate material, and the wet lithium sulfate material is put into a drying oven for drying to obtain lithium sulfate monohydrate, which is labeled as example 4.

Comparative example: adding pure water to dilute a proper amount of concentrated sulfuric acid, then acidifying the battery-grade lithium carbonate, filtering the solution, evaporating and concentrating, cooling and crystallizing, filtering to obtain lithium sulfate crystals, then adding pure water, stirring and washing, filtering, then adding pure water for leaching to obtain a wet lithium sulfate material, and drying in a drying oven to obtain lithium sulfate monohydrate, wherein the label is example 5.

The results of the component analysis obtained in the above examples 1 to 5 are shown in Table 1 below:

sample numbering	Li2SO4	Na	K	Ca
					Example 1	99.05%	0.027%	0.021%	0.030%
Example 2	99.11%	0.031%	0.019%	0.028%
					Example 3	99.09%	0.043%	0.022%	0.025%
Example 4	99.12%	0.036%	0.018%	0.027%
					Example 5	99.20%	0.018%	0.009%	0.013%

The comparison of the results in table 1 shows that the main content and the impurity content of the products obtained by the two methods are not greatly different, but the evaporation input production cost of the sulfuric acid acidification battery level lithium carbonate of the control group is obviously higher, and the cost for preparing the product by taking spodumene as the raw material of the experimental group is lower, so that the method can better embody the great advantages of the method in the actual production and is suitable for industrial and adolescent factories to produce lithium sulfate monohydrate in a large batch.

Compared with other lithium salt preparation methods, the method for preparing lithium sulfate monohydrate by using spodumene has the following characteristics: the lithium sulfate monohydrate obtained by the method has high purity and meets the requirement of Li₂SO₄·H₂More than or equal to 99 percent of O, less than or equal to 0.03 percent of Na and less than or equal to 0.04 percent of K. Compared with the traditional preparation method of lithium sulfate monohydrate, namely a method for preparing the lithium sulfate monohydrate by acidifying lithium carbonate or lithium hydroxide with sulfuric acid, evaporating, concentrating, cooling, crystallizing, centrifugally separating and drying, the method has the advantages of simple process, low cost of reaction raw materials, low impurity content of products, continuous and large-scale production and great advantage.

The above description is only for the purpose of illustrating the technical solutions of the present invention and not for the purpose of limiting the same, and other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention should be covered within the scope of the claims of the present invention without departing from the spirit and scope of the technical solutions of the present invention.