阅读说明：本技术 一种采用硝酸加压法处理锂云母生产多种锂产品的方法 (Method for producing various lithium products by processing lepidolite through nitric acid pressurization method ) 是由 赵林 何永 但勇 金长浩 高波 宋世杰 刘芸秀 于 2021-09-09 设计创作，主要内容包括：本发明公开一种采用硝酸加压法处理锂云母生产多种锂产品的方法,属于矿物资源综合回收利用技术领域。该方法以硝酸为溶剂介质,在加压条件下对锂云母煅烧物料进行浸出反应,并通过化学沉淀及蒸发结晶获得单水氢氧化锂产品；结晶母液经浓缩煅烧后的产物用于制备碳酸锂、氧化镁、硝酸和钾肥产品。本发明能够同时制备出单水氢氧化锂、碳酸锂两种锂产品及氧化镁附产品,突破了现有锂云母提锂工艺仅能生产单一锂产品的局限；并且,本发明实现了酸碱介质氧化镁和硝酸的循环利用,改善了传统锂云母处理工艺中存在的产渣量大的问题,降低了工艺生产成本,增大了产品附加值,最大程度实现了锂云母的资源化利用,同时,整体工艺简单高效,易于实现工业化生产。(The invention discloses a method for producing various lithium products by treating lepidolite through a nitric acid pressurization method, and belongs to the technical field of comprehensive recycling of mineral resources. The method takes nitric acid as a solvent medium, carries out leaching reaction on a lepidolite calcined material under a pressurized condition, and obtains a lithium hydroxide monohydrate product through chemical precipitation and evaporative crystallization; the product of the crystallization mother liquor after concentration and calcination is used for preparing lithium carbonate, magnesium oxide, nitric acid and potash fertilizer products. The method can simultaneously prepare two lithium products of lithium hydroxide monohydrate and lithium carbonate and a magnesium oxide byproduct, and breaks through the limitation that the existing lepidolite lithium extraction process can only produce a single lithium product; in addition, the recycling of acid and alkali media magnesium oxide and nitric acid is realized, the problem of large slag yield in the traditional lepidolite treatment process is solved, the process production cost is reduced, the added value of the product is increased, the resource utilization of the lepidolite is realized to the maximum extent, and meanwhile, the whole process is simple and efficient and is easy to realize industrial production.)

1. A method for producing various lithium products by processing lepidolite by a nitric acid pressurization method is characterized by comprising the following steps:

step S1: uniformly mixing the lepidolite with a proper amount of water, and calcining for 2-3h at the temperature of 900-1300 ℃;

step S2: crushing the calcined material obtained in the step S1, uniformly mixing the crushed material with a proper amount of water, then adding a proper amount of nitric acid, leaching for 2-6h under a pressurizing condition, and filtering and washing the obtained solid-liquid mixture after the reaction is finished to obtain a leaching solution and leaching residues;

step S3: adding MgO into the leachate obtained in the step S2, adjusting the pH value to 3.5-6.0, fully stirring at the temperature of 40-80 ℃, standing after the reaction is finished, and filtering to obtain filtrate I and filter residue I;

step S4: adding MgO into the filtrate I obtained in the step S3, adjusting the pH value to 10-14, fully stirring at the temperature of 40-80 ℃, standing after the reaction is finished, and filtering to obtain filtrate II and filter residue II;

step S5: evaporating and crystallizing the filtrate II obtained in the step S4 to obtain LiOH & H₂O product and crystallization mother liquor;

step S6: concentrating the crystallization mother liquor obtained in the step S5, calcining, washing the calcined product with water to obtain a mixed liquor containing LiOH and KOH and an MgO byproduct, and introducing CO into the mixed liquor₂Carrying out carbonization reaction, washing and filtering, and drying the obtained filter residue to obtain Li₂CO₃And (5) producing the product.

2. The method for producing a plurality of lithium products by processing lepidolite through a nitric acid pressurization method according to claim 1, wherein the liquid-solid ratio of the mixture of lepidolite and water in step S1 is 1: 0.1-0.5.

3. The method for producing a plurality of lithium products by processing lepidolite using a nitric acid pressing method according to claim 1, wherein the calcined material is pulverized to have a maximum particle size of less than 48 μm in step S2; the liquid-solid ratio of the crushed materials to the water is 2.5-6: 1.

4. The method for producing a plurality of lithium products by processing lepidolite through a nitric acid pressurization method as claimed in claim 1, wherein the nitric acid in step S2 is concentrated nitric acid with a mass concentration of more than 60%, the addition amount of the nitric acid is calculated by 100-150% of the theoretical amount required by the reaction of the nitric acid and the elements Fe, Mn, Al and Li in the lepidolite, the temperature of the leaching reaction is 130-180 ℃, and the pressure of the leaching reaction is 0.2-1.2 Mpa.

5. The method for producing a plurality of lithium products by processing lepidolite through a nitric acid pressurization method according to claim 1, wherein the stirring time in step S3 is 0.5 to 4 hours.

6. The method for producing a plurality of lithium products by processing lepidolite through a nitric acid pressurization method according to claim 1, wherein the stirring time in step S4 is 0.5 to 4 hours.

7. The method for producing various lithium products by processing lepidolite through a nitric acid pressing method according to claim 1, wherein the crystallization temperature in step S5 is 30-60 ℃.

8. The method for producing a plurality of lithium products by processing lepidolite through a nitric acid pressurization method as claimed in claim 1, wherein the calcination temperature in step S6 is 400-600 ℃; the calcined product comprises K₂O, MgO and Li₂O solid mixture and NO₂。

9. The method for producing a plurality of lithium products by processing lepidolite through a nitric acid pressurization method according to claim 1, wherein the filtrate obtained through the filtration in the step S6 is a KOH solution.

10. The method for producing a plurality of lithium products by processing lepidolite through a nitric acid pressing method according to claim 1, wherein step S6 further comprises calcining NO obtained from the product₂The nitric acid is used for preparing nitric acid, and the prepared nitric acid is returned to the step S2 for recycling; the MgO obtained in the calcined product returns to the step S3 and the step S4 for recycling; filtering to obtain KOH filtrate for preparing potash fertilizer products.

Technical Field

The invention belongs to the technical field of comprehensive recycling of mineral resources, and particularly relates to a method for producing various lithium products by treating lepidolite through a nitric acid pressurization method.

Background

At present, lithium resources are the most important raw materials in strategic fields of new energy automobiles, energy storage, controlled thermonuclear reaction, electronic information and the like, wherein lithium carbonate and lithium hydroxide are very important lithium resources, and the rest lithium resources are basically derivatives thereof. In 2019, China has become the first lithium resource consuming country in the world, but lithium resources mainly depend on imports. Although lithium resources obtained from salt lakes have become popular sources around the world due to their relatively low cost, the magnesium-lithium content in salt lakes in our country is relatively high, and the difficulty factor for extracting lithium from salt lakes is relatively high. In China, most lithium products are made of lithium minerals. Therefore, it is very important to research the lithium resource obtained from lithium ore to reduce the dependence of China on imported lithium resources.

The lepidolite is one of important lithia resources, not only contains abundant lithium elements, but also contains various valuable metal and nonmetal elements such as potassium, sodium, aluminum and the like, so that the comprehensive development of lepidolite for extracting lithium to prepare a series of lithium products has extremely high economic value.

The existing lithium extraction process of lepidolite mainly comprises a sulfuric acid method, a sulfate roasting method, a chloride roasting method, a limestone roasting method and a pressure boiling method. However, the processes have a series of problems that the raw materials for leaching the lepidolite cannot be recycled, the slag yield is large, the single lithium product is produced in a heavier way, the comprehensive utilization rate of the raw materials is low, and the like.

Disclosure of Invention

Aiming at the technical problems of large slag yield, production of single lithium product, low comprehensive utilization rate of raw materials and the like in the traditional lepidolite lithium extraction process, the invention provides a method for producing various lithium products by treating lepidolite by a nitric acid pressurization method. The method takes nitric acid as a solvent medium, carries out leaching reaction on a lepidolite calcined material under a pressurized condition, and obtains a lithium hydroxide monohydrate product through chemical precipitation and evaporative crystallization; the product of the crystallization mother liquor after concentration and calcination is used for preparing lithium carbonate, magnesium oxide, nitric acid and potash fertilizer products. The method disclosed by the invention realizes the recycling of acid-base medium magnesium oxide and nitric acid, solves the problem of large slag yield in the traditional lepidolite treatment process, reduces the process production cost, increases the product additional value, realizes the resource utilization of lepidolite to the maximum extent, and simultaneously has simple and efficient integral process and easy realization of industrial production.

In order to solve the technical problems, the invention provides the following technical scheme:

a method for producing various lithium products by processing lepidolite by a nitric acid pressurization method comprises the following steps:

step S1: uniformly mixing the lepidolite with a proper amount of water, and calcining for 2-3h at the temperature of 900-1300 ℃;

step S2: crushing the calcined material obtained in the step S1, uniformly mixing the crushed material with a proper amount of water, then adding a proper amount of nitric acid, leaching for 2-6h under a pressurizing condition, and filtering and washing the obtained solid-liquid mixture after the reaction is finished to obtain a leaching solution and leaching residues;

step S3: adding MgO into the leachate obtained in the step S2, adjusting the pH value to 3.5-6.0, fully stirring at the temperature of 40-80 ℃, standing after the reaction is finished, and filtering to obtain filtrate I and filter residue I;

step S4: adding MgO into the filtrate I obtained in the step S3, adjusting the pH value to 10-14, fully stirring at the temperature of 40-80 ℃, standing after the reaction is finished, and filtering to obtain filtrate II and filter residue II;

step S5: evaporating and crystallizing the filtrate II obtained in the step S4 to obtain LiOH & H₂O product and crystallization mother liquor;

step S6: concentrating the crystallization mother liquor obtained in the step S5, calcining, washing the calcined product with water to obtain a mixed liquor containing LiOH and KOH and an MgO byproduct, and introducing CO into the mixed liquor₂Carrying out carbonization reaction, washing and filtering, and drying the obtained filter residue to obtain Li₂CO₃And (5) producing the product.

Further, the liquid-solid ratio of the mixture of the lepidolite and the water in the step S1 is 1: 0.1-0.5.

In the step, water participates in the chemical reaction generated in the calcining process, so that fluorine in the lepidolite is volatilized in the form of hydrogen fluoride, and the lepidolite is convenient to recycle.

Further, the calcined material is pulverized to have a maximum particle size of less than 48 μm in step S2; the liquid-solid ratio of the crushed materials to the water is 2.5-6: 1.

Further, in the step S2, the nitric acid is concentrated nitric acid with a mass concentration of more than 60%, the adding amount of the nitric acid is calculated by 100-150% of the theoretical amount required by the reaction of the nitric acid and Fe, Mn, Al and Li elements in the lepidolite, the temperature of the leaching reaction is 130-180 ℃, and the pressure of the leaching reaction is 0.2-1.2 MPa.

In the step, the nitric acid is used for pressure leaching, so that the reaction speed is higher, the reaction of the main element lithium is more thorough, and the leaching rate and the yield of lithium can be further improved. The main component of the leaching residue produced in the process is insoluble silicate.

Further, the stirring time in step S3 is 0.5 to 4 hours.

In the step, the main components of the filtrate I are lithium nitrate, potassium nitrate, manganese nitrate, magnesium nitrate and the like, and the main components of the filter residue I are ferric hydroxide, aluminum hydroxide, silicate and the like

Further, the stirring time in step S4 is 0.5 to 4 hours.

In the step, the main components of the filtrate II are lithium nitrate, potassium nitrate, magnesium nitrate and the like, and the main components of the filter residue II are manganese hydroxide, other trace insoluble hydroxides, phosphates, silicates and the like.

Further, the crystallization temperature in step S5 is 30-60 ℃.

Further, the calcination temperature in step S6 is 400-600 ℃; the calcined product comprises K₂O, MgO and Li₂O solid mixture and NO₂。

Further, the filtrate obtained by the filtration in step S6 is a KOH solution.

Further, step S6 includes calcining the NO obtained from the product₂The nitric acid is used for preparing nitric acid, and the prepared nitric acid is returned to the step S2 for recycling; the MgO obtained in the calcined product returns to the step S3 and the step S4 for recycling; filtering to obtain KOH filtrate for preparing potash fertilizer products.

Compared with the prior art, the technical scheme of the invention has the beneficial effects that:

(1) according to the invention, lepidolite is treated by a nitric acid pressurization method, the high leaching rate of lithium is ensured, and meanwhile, acid and alkali media (magnesium oxide and nitric acid) used in the process can be regenerated and recycled;

(2) the method can simultaneously prepare two lithium products of lithium hydroxide monohydrate and lithium carbonate and the byproduct magnesium oxide, wherein about 70 percent of the lithium hydroxide monohydrate and about 30 percent of the lithium carbonate are lithium carbonate products, and the byproduct magnesium oxide is recycled, so that the limitation that the existing lepidolite lithium extraction process can only produce a single lithium product is broken through;

(3) the invention also produces a byproduct potassium fertilizer product at the same time, and realizes the resource utilization of the lepidolite to the maximum extent;

(4) the materials used in the invention are common industrial products, are easy to purchase and have low price, and the whole process flow is simple, so that large-scale production can be realized.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a process flow diagram of the method for producing various lithium products by treating lepidolite with a nitric acid pressurization method according to the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

The results of analyzing the chemical element composition of the lepidolite raw materials treated in examples 1 to 3 are shown in table 1.

TABLE 1 analysis results of chemical element composition of lepidolite

Example 1

The method for producing various lithium products by treating lepidolite through nitric acid pressure leaching specifically comprises the following steps:

step 1: uniformly mixing the lepidolite with water according to the mass ratio of 1:0.3, and calcining for 3 hours at 900 ℃.

Step 2: crushing the calcined material obtained in the step 1, controlling the maximum particle size of the calcined material to be less than 48 microns, mixing and stirring water and the calcined material uniformly according to the liquid-solid mass ratio of 3:1, then adding nitric acid with the theoretical amount of 110%, carrying out pressure leaching reaction for 3 hours at the temperature of 150 ℃, wherein the leaching reaction pressure is 0.8Mpa, and filtering and washing a solid-liquid mixture after the reaction to obtain a leaching solution and leaching residues.

And step 3: adding MgO into the leachate obtained by filtering in the step 2, adjusting the pH value of the leachate to 3.5, stirring for 1h at the reaction temperature of 60 ℃, and then filtering and washing to obtain filtrate I and filter residue I.

And 4, step 4: and (3) continuously adding MgO into the filtrate I obtained in the step (3), adjusting the pH value of the filtrate I to 12, stirring for 1h at the reaction temperature of 60 ℃, and then filtering and washing to obtain a filtrate II and filter residues II, wherein the filtrate II is used for preparing various lithium products, potassium fertilizers and nitric acid.

And 5: at a temperature of 50 ℃, the stepsEvaporating and crystallizing the filtrate II obtained in the step 4 to obtain LiOH & H₂O products and crystallization mother liquor.

Step S6: concentrating the crystallization mother liquor obtained in the step S5, calcining at 500 ℃, washing the calcined product with water to obtain a mixed liquor containing LiOH and KOH and an MgO byproduct, and introducing CO into the mixed liquor₂Carrying out carbonization reaction, filtering and washing, and drying the obtained filter residue to obtain Li₂CO₃And (5) producing the product. NO produced during calcination₂For the preparation of HNO₃The carbonized mother liquor is KOH solution and can be used for preparing potassium fertilizer or other potassium products.

Example 2

The method for producing various lithium products by treating lepidolite through nitric acid pressure leaching specifically comprises the following steps:

step 1: uniformly mixing the lepidolite with water according to the mass ratio of 1:0.1, and calcining for 2 hours at 1300 ℃.

Step 2: crushing the calcined material obtained in the step 1, controlling the maximum particle size of the calcined material to be less than 48 microns, mixing and stirring water and the calcined material uniformly according to the liquid-solid mass ratio of 2.5:1, then adding nitric acid with the theoretical amount of 100%, carrying out pressure leaching reaction at the temperature of 130 ℃ for 6 hours at the leaching reaction pressure of 1.2Mpa, and filtering and washing the solid-liquid mixture after the reaction to obtain leachate and leaching residues.

And step 3: adding MgO into the leachate obtained by filtering in the step 2, adjusting the pH value of the leachate to 6.0, stirring for 0.5h at the reaction temperature of 40 ℃, and then filtering and washing to obtain filtrate I and filter residue I.

And 4, step 4: and (3) continuously adding MgO into the filtrate I obtained in the step (3), adjusting the pH value of the filtrate I to 14, stirring for 0.5h at the reaction temperature of 40 ℃, and then filtering and washing to obtain a filtrate II and filter residues II, wherein the filtrate II is used for preparing various lithium products, potassium fertilizers and nitric acid.

And 5: evaporating and crystallizing the filtrate II obtained in the step 4 at the temperature of 30 ℃ to obtain LiOH & H₂O products and crystallization mother liquor.

Step S6: concentrating the crystallization mother liquor obtained in the step S5, and calcining at 600 DEG CBurning, washing the calcined product with water to obtain a mixed solution containing LiOH and KOH and an MgO byproduct, and introducing CO into the mixed solution₂Carrying out carbonization reaction, filtering and washing, and drying the obtained filter residue to obtain Li₂CO₃And (5) producing the product. NO produced during calcination₂For the preparation of HNO₃The carbonized mother liquor is KOH solution and can be used for preparing potassium fertilizer or other potassium products.

Example 3

The method for producing various lithium products by treating lepidolite through nitric acid pressure leaching specifically comprises the following steps:

step 1: uniformly mixing the lepidolite with water according to the mass ratio of 1:0.5, and calcining for 2 hours at 1100 ℃.

Step 2: crushing the calcined material obtained in the step 1, controlling the maximum particle size of the calcined material to be less than 48 microns, mixing and stirring water and the calcined material uniformly according to the liquid-solid mass ratio of 6:1, then adding nitric acid with the theoretical quantity of 150%, carrying out pressure leaching reaction for 2 hours at the temperature of 180 ℃, wherein the leaching reaction pressure is 0.2Mpa, and filtering and washing a solid-liquid mixture after the reaction to obtain a leaching solution and leaching residues.

And step 3: adding MgO into the leachate obtained by filtering in the step 2, adjusting the pH value of the leachate to 5.0, stirring for 4 hours at the reaction temperature of 80 ℃, and then filtering and washing to obtain filtrate I and filter residue I.

And 4, step 4: and (3) continuously adding MgO into the filtrate I obtained in the step (3), adjusting the pH value of the filtrate I to 10, stirring for 4 hours at the reaction temperature of 80 ℃, and then filtering and washing to obtain a filtrate II and filter residue II, wherein the filtrate II is used for preparing various lithium products, potassium fertilizers and nitric acid.

And 5: evaporating and crystallizing the filtrate II obtained in the step 4 at the temperature of 60 ℃ to obtain LiOH & H₂O products and crystallization mother liquor.

Step S6: concentrating the crystallization mother liquor obtained in the step S5, calcining at 400 ℃, washing the calcined product with water to obtain a mixed liquor containing LiOH and KOH and an MgO byproduct, and introducing CO into the mixed liquor₂Carrying out carbonization reaction, filtering and washing, and drying the obtained filter residue to obtain Li₂CO₃And (5) producing the product. NO produced during calcination₂For the preparation of HNO₃The carbonized mother liquor is KOH solution and can be used for preparing potassium fertilizer or other potassium products.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.