WO2020057042A1

WO2020057042A1 - Method for extracting lithium from amblygonite and preparing iron-containing phosphate

Info

Publication number: WO2020057042A1
Application number: PCT/CN2019/073871
Authority: WO
Inventors: 孔令涌; 尚伟丽; 李洁凤; 黄少真
Original assignee: 深圳市德方纳米科技股份有限公司
Priority date: 2018-09-21
Filing date: 2019-01-30
Publication date: 2020-03-26
Also published as: CN108862227A; CN108862227B

Abstract

Provided is a method for extracting lithium from amblygonite and preparing iron-containing phosphate, comprising the following steps: (1) processing amblygonite to dissolve lithium to obtain the dissolution; (2) performing solid-liquid separation on the dissolution in step (1) to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate; and (3) leaching the aluminum phosphate-containing precipitate in step (2) by using an acidic solution, adding an iron source to a leach solution, adding an alkaline substance for adjusting the pH, and then performing solid-liquid separation to obtain the iron-containing phosphate.

Description

Method for extracting lithium from hepatite and preparing iron-containing phosphate

Technical field

The present application belongs to the technical field of metal extraction and separation, and relates to a method for extracting lithium, for example, a method for extracting lithium from hepatite and preparing an iron-containing phosphate.

Background technique

Lithium is one of the lightest metals. Lithium metal and its alloys and compounds have been used in nuclear power generation, light high-strength alloys, metallurgy, aluminum smelting, high-energy batteries, medicine, glass, ceramics, greases, petroleum, chemicals, organic It is widely used in many fields such as synthesis, welding of light metals, surface modification of non-metallic minerals and production of daily necessities. In recent decades, the United States, Britain, Germany, France, Japan, Russia and other countries have invested a lot of capital and manpower and material resources to conduct research and development of aluminum-lithium alloys, magnesium-lithium alloys, and in-depth development and application of lithium resources. The remarkable achievements and success have promoted the development, application, production, consumption and trade of lithium resources in the world, and have played an important role in the development of the world lithium industry.

The world is rich in lithium resources. Lithium resources are mainly distributed in South, North America, Asia, Australia and Africa. In Bolivia only Pooh salt basin of Li ₂ O reserves, which amounts to 19,135,000 t; Nevada Silver Peak (Silver Peak) and both California Sylvan Lake Li ₂ O reserves of over 10 million t; police of Qinghai The Erhan Salt Lake and Chaidan Salt Lake, as well as many brines in Sichuan Province, have estimated lithium resource reserves of about 10 million tons. Lithium reserves of the brine brine deposits in Catabaca Province, Argentina are also considerable, and its Li ₂ O reserves are estimated to reach millions of tons. Reserves based on Li ₂ O in pegmatite lithium deposits are 6.348 million tons in the United States, 4.26 million tons in Chile, 6.6 million tons in Canada, and 6 million tons of Li ₂ O reserves in the Greenbushes spodumene mine in western Australia. Lithium-phosphite Li ₂ O reserves are also relatively large in Zimbabwe and Namibia. Lithium mica reserves in deposits such as Cocotohai, Xinjiang, Spodumene in northwestern Sichuan, and Yichun tantalum-niobium-lithium-cesium polymetallic deposits in Jiangxi are also very large rich.

There have been many reports on the lithium extraction methods of spodumene, diabase feldspar, and lithium mica, but little research has been done on the lithium extraction of hectorite.

CN107188205A discloses a process for extracting lithium sulfate from lithium apatite by an acidification method. The process includes the following steps: (1) grinding of raw materials: grinding of raw materials in lithium apatite; (2) ingredients: Step (1) mixing the ground lithium phospatite and concentrated sulfuric acid; (3) roasting: roasting the mixed material in step (2); (4) slurry leaching: placing the clinker in step (3) Add water to the reactor for heating and stirring; (5) Purify and remove impurities: remove impurities such as aluminum or calcium from the solution leached in step (4); (6) evaporate the solution after the reaction is completed in step (5) concentrate.

CN107162024A discloses a process for extracting lithium carbonate from lithium apatite by an acidification method. The process includes the following steps: grinding the raw materials → batching → mixing the ground lithium aluminite and concentrated sulfuric acid → roasting → slurry leaching → Purification and removal of impurities → Removal of impurities such as aluminum or calcium → Evaporation and concentration → Sinking lithium once> Single washing → Second stirring> Drying to obtain lithium carbonate products.

CN107200338A discloses a process for extracting lithium hydroxide from lithium apatite by an acidification method. The process route is as follows: the lithium apatite is ground and mixed with concentrated sulfuric acid → roasting → clinker grinding and leaching → purification and removal Miscellaneous → Evaporation and concentration → Causticization → Freezing sodium precipitation → Evaporation and crystallization → Recrystallization → Drying and packaging. By applying the process technology of the present invention, lithium can be extracted from lithium apatite and turned into a standard monohydrated lithium hydroxide product, and the yield of lithium can reach more than 86%.

CN107188204A discloses a process for extracting lithium hydroxide from lithium apatite by the lime method, which includes the following steps: S1 raw material is ground and ground to 100-200 mesh; S2 ingredients are uniformly mixed into a raw material; S3 roasting and high temperature roasting S4 is leached and filtered to obtain a lithium hydroxide solution; S5 is evaporated and concentrated to obtain a lithium hydroxide clear solution; and S6 is crystallized to obtain lithium hydroxide crystals.

Although the above methods can achieve lithium extraction from lithium apatite, the process route is relatively long, and the extraction rate of lithium extraction needs to be improved. The purity of lithium-containing products also needs to be further improved. In addition, iron and phosphorus in lithium apatite Underutilized.

Therefore, the development of a method for extracting lithium from lithium apatite has a short process, a higher lithium extraction rate, less impurities in the obtained lithium-containing products, and a fuller use of the phosphorus element in lithium apatite Obtaining iron phosphate and / or ferrous phosphate is of great significance in the art.

Summary of the Invention

The following is an overview of the topics detailed in this article. This summary is not intended to limit the scope of protection of the claims.

The purpose of the present application is to provide a method for extracting lithium from lithium apatite and preparing iron-containing phosphate. The method has a short process flow, a higher extraction rate of lithium elements, and a more pure and sufficient lithium-containing product. The ground utilizes the phosphorus element in hectorite.

To achieve this, the following technical solutions are used in this application:

The present application provides a method for extracting lithium from lithium apatite and preparing an iron-containing phosphate. The method includes the following steps:

(1) treating lithium phospatite to dissolve lithium to obtain an eluate;

(2) performing solid-liquid separation on the eluate in step (1) to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate;

(3) leaching the aluminum phosphate-containing precipitate in step (2) with an acid solution, adding an iron source to the leaching solution, adding an alkaline substance to adjust the pH, and then solid-liquid separation to obtain iron-containing phosphate.

The preparation method provided in the present application first treats lithium apatite, so that it dissolves lithium, and thereby obtains a high-quality lithium-containing solution product (wherein the solute is a lithium salt), and such products can be evaporated or the like. The processing method removes the solvent to obtain a solid lithium-containing product such as a lithium salt or lithium hydroxide, and can be processed by adding various acid radicals to a desired lithium-containing product or directly using it in a solution.

In step (3) of the present application, by adjusting the pH, the iron ions (divalent and / or trivalent) in the iron source are combined with the phosphate ions leached by the acid solution to form a precipitate, while the aluminum ions leached by the acid still exist in the In solution.

The following is an optional technical solution of the present application, but is not a limitation on the technical solution provided by the present application. Through the following optional technical solutions, the technical objectives and beneficial effects of the present application can be better achieved and realized.

As an optional technical solution of the present application, in step (1), the method for treating lithium apatite to dissolve lithium includes the following steps: heat treating the lithium apatite to generate an aluminum phosphate phase, and converting the treated lithium phosphorous Bauxite is mixed with an acidic substance to dissolve lithium.

Here, the purpose of processing lithium apatite is to transform it into an aluminum phosphate phase, which can ensure that only lithium is dissolved out when it is subsequently mixed with an acidic substance.

As an optional technical solution of the present application, the heat treatment method includes roasting and / or microwave induction.

Optionally, the roasting temperature is 600-1100 ° C, such as 600 ° C, 700 ° C, 800 ° C, 900 ° C, 1000 ° C, or 1100 ° C, etc., but it is not limited to the listed values. The listed values also apply.

Optionally, the roasting time is 0.1-6h, for example, 0.1h, 0.5h, 1h, 2h, 3h, 4h, 5h, or 6h, etc., but it is not limited to the listed values. Other values in this range are not listed. The same applies.

Optionally, the mass ratio of the calcined hectorite to the acidic substance is 1: (0.3-0.5), such as 1: 0.3, 1: 0.35, 1: 0.4, 1: 0.45, 1: 0.5, etc., However, it is not limited to the listed values, and other unlisted values in this range are also applicable.

Optionally, the firing atmosphere includes any one or a combination of at least two of an air atmosphere, a nitrogen atmosphere, an argon atmosphere, a helium atmosphere, or a hydrogen atmosphere.

Optionally, the roasting is performed in a tube furnace or a muffle furnace.

Optionally, the microwave-induced microwave power is 500-700W, for example, 500W, 550W, 600W, 650W, or 700W, etc., but it is not limited to the listed values, and other unlisted values within this range are also applicable.

Optionally, the microwave induction time is 30-50 minutes, such as 30min, 35min, 40min, 45min, or 50min, etc., but it is not limited to the listed values, and other unlisted values in this value range are also applicable.

Optionally, the mixing temperature is 20-300 ° C, such as 20 ° C, 25 ° C, 30 ° C, 50 ° C, 100 ° C, 150 ° C, 200 ° C, 250 ° C or 300 ° C, etc., but it is not limited to the enumeration The same applies to other unlisted values in this value range. Here, if the temperature is too high, it will cause more side reactions, affect the purity, and increase the difficulty of post-processing; if the temperature is too low, it will lead to incomplete dissolution of lithium or inability to dissolve lithium.

Optionally, the mixing time is 1-5h, for example, 1h, 2h, 3h, 4h, or 5h, etc., but it is not limited to the listed values, and other unlisted values in the value range are also applicable.

Optionally, the acidic substance includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid.

Optionally, spodumene is crushed before roasting.

Optionally, the method of crushing includes grinding and / or sieving.

As an optional technical solution of the present application, in step (1), the method for treating lithium apatite to dissolve lithium includes the following steps: mixing the lithium apatite and an acidic substance, and heating the obtained mixture. An aluminum phosphate phase was generated, and a solvent was added to dissolve lithium after the treatment.

This method can realize the acid leaching of lithium aluminite into an aluminum phosphate phase and lithium apatite when processing a mixture of lithium apatite and an acidic substance. Subsequent addition of a solvent (such as water) without the addition of an acid solution can achieve the dissolution of lithium.

As an optional technical solution of the present application, the acidic substance includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid.

Optionally, the mass ratio of the lithium apatite to the acidic substance is 1: (0.3-0.5), 1: 0.3, 1: 0.35, 1: 0.4, 1: 0.45 or 1: 0.5, etc., but it is not limited to The listed values are also applicable to other unlisted values within the numerical range.

Optionally, the method of heat treatment includes roasting and / or microwave induction.

Optionally, the heating rate of the roasting is 0.5-5 ° C / min, such as 0.5 ° C / min, 1 ° C / min, 2 ° C / min, 3 ° C / min, 4 ° C / min, or 5 ° C / min, etc., However, it is not limited to the listed values, and other unlisted values in this range are also applicable. Here, if the heating rate is too fast, it may cause the acidic substance to vaporize too quickly without sufficiently reacting with the kevlar.

Optionally, the roasting is performed in a tube furnace or a muffle furnace.

Optionally, the solvent includes any one or a combination of at least two of water, ethanol, methanol, propanol, or hexane, and may be water.

Optionally, before the solvent is added after calcination, the lithium apatite is crushed.

Optionally, the method of crushing includes grinding and / or sieving.

As an optional technical solution of the present application, in step (2), the method for solid-liquid separation includes filtration and / or centrifugation.

Optionally, in step (2), the method further includes: purifying the lithium-containing solution.

Optionally, the purification method includes any one or a combination of at least two of extraction, crystallization, or precipitation. Here, the purification is to remove calcium, magnesium, or sodium ions that may be present in the lithium-containing solution.

Optionally, in step (2), the method further includes: performing solvent removal on the lithium-containing solution to obtain a lithium-containing solid product. Optionally, in step (2), the method further comprises: adding an acidic salt or base of the acid in step (1) to the lithium-containing solution. If sulfuric acid is added for dissolution in step (1), sodium carbonate is added to the lithium-containing solution to prepare lithium carbonate or sodium hydroxide is added to prepare lithium hydroxide.

Optionally, the method for removing the solvent includes any one or a combination of at least two of evaporation of the solvent, crystallization separation, or lithium carbide precipitation.

Optionally, the lithium-containing solid product is one of lithium salt products such as lithium sulfate, lithium phosphate, lithium nitrate, lithium chloride, lithium carbonate, and lithium hydroxide.

Optionally, the lithium salt and / or lithium-containing solid can be used to prepare cathode materials such as lithium iron phosphate and ternary.

The lithium salt and / or lithium-containing solid is mixed with a lithium iron phosphate precursor and sintered under an inert atmosphere to obtain a lithium iron phosphate material; the lithium salt and / or a ternary precursor is mixed and placed in aerobic The ternary material was sintered under the atmosphere.

The ternary material includes nickel-cobalt-manganese, nickel-cobalt-aluminum.

The positive electrode material also includes lithium nickelate, lithium cobaltate, lithium manganese iron phosphate, lithium manganate, lithium iron silicate, and the like.

As an optional technical solution of the present application, in step (3), the acid solution includes a nitric acid solution and / or a hydrochloric acid solution.

Optionally, when the acid solution is a nitric acid solution, the mass fraction of the solute in the nitric acid solution is ≧ 68% by weight. That is, concentrated nitric acid is used to dissolve phosphorus in the aluminum phosphate phase.

Optionally, when the acid solution is a hydrochloric acid solution, the mass fraction of the solute in the hydrochloric acid solution is ≧ 20% by weight. That is, concentrated hydrochloric acid is used to dissolve phosphorus in the aluminum phosphate phase.

As an optional technical solution of the present application, in step (3), the iron source includes iron oxide, ferrous oxide, ferric chloride, ferrous chloride, ferric sulfate, ferrous sulfate, ferric nitrate, ferrous nitrate, Any one or a combination of at least two of iron carbonate or ferrous carbonate.

Optionally, in step (3), the alkaline substance includes any one or a combination of at least two of ammonia water, sodium hydroxide, or potassium hydroxide.

As an optional technical solution of the present application, in step (3), the basic substance is a solution of the basic substance.

Optionally, in step (3), the method for adding the basic substance is dropwise addition.

Optionally, the dropping rate is 0.1-2 mL / min, such as 0.1 mL / min, 0.5 mL / min, 1 mL / min, 1.5 mL / min, or 2 mL / min, etc., but it is not limited to the listed values , Other values not listed in this value range also apply.

In the present application, the size range of the iron phosphate and / or ferrous phosphate obtained by adjusting the dropping rate can be used, and the method of the present application can control the size range of the iron phosphate and / or ferrous phosphate to 50-1000 nm.

Optionally, in step (3), the pH is adjusted to a pH value of 1-3, such as 1, 1.5, 2, 2.5, or 3, etc., but it is not limited to the listed values, and other unlisted values within the value range The same applies, optional 2. Here, if the pH value is too low, iron ions will not be precipitated to form iron phosphate; if the pH value is too high, aluminum ions will be precipitated to form aluminum phosphate precipitates, and at the same time, precipitates such as aluminum hydroxide and sodium iron hydroxide will be caused. Therefore, the obtained iron phosphate precipitates impure.

Optionally, in step (3), the pH is adjusted with stirring and mixing.

Optionally, in step (3), the solid-liquid separation includes filtration separation and / or centrifugation.

Optionally, in step (3), the iron-containing phosphate includes iron phosphate and / or ferrous phosphate.

Optionally, the iron phosphate and / or ferrous phosphate is used for preparing lithium iron phosphate. Here, lithium iron phosphate includes lithium iron phosphate and a lithium iron phosphate precursor required for preparing lithium iron phosphate.

Optionally, the method for synthesizing lithium iron phosphate includes a solid phase method, a hydrothermal method, a liquid phase method, a sol-gel method, and the like.

Optionally, the lithium iron phosphate is doped.

Optionally, carbon coating is performed on the lithium iron phosphate to obtain lithium iron phosphate containing a carbon coating layer.

Optionally, the lithium iron phosphate doping element may be one or more of Co, Ni, Mg, Mn, Zr, Ti, V, F and the like.

Optionally, the lithium iron phosphate carbon coating layer is graphene, conductive carbon, carbon nanotubes, or the like.

Optionally, the carbon source is mixed with a lithium iron phosphate precursor so that the carbon source can be pyrolyzed and form a carbon coating during the sintering process.

As an optional technical solution of the method described in this application, the method includes the following steps:

(1) Crushing the wollastonite, and then firing the wollastonite at 600-1100 ° C in an air atmosphere for 0.1-6h. The roasted wollastonite and the acidic substance are in a mass of 1: (0.3-0.5). Than mixing to dissolve lithium, the mixing temperature is 20-300 ° C, and the mixing time is 1-5h to obtain an eluate;

(2) filtering and separating the eluate in step (1) to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate, and purifying the lithium-containing solution to obtain a purified lithium-containing solution;

(3) leaching the aluminum phosphate-containing precipitate in step (2) with an acid solution, and then adding an iron source to the leaching solution; adding alkaline substances dropwise at a rate of 0.1-2 mL / min to adjust the pH to 2 and stirring and mixing, Thereafter, it is separated by filtration to obtain iron phosphate and / or ferrous phosphate.

Compared with related technologies, this application has the following beneficial effects:

(1) The method for extracting lithium from lithium apatite and preparing an iron-containing phosphate provided by the present application is simple in operation, short in process, and low in cost, and adopts a roasting and / or microwave-induced processing method to generate lithium apatite into phosphoric acid After the aluminum phase is dissolved, a high solids-liquid extraction rate can be obtained by simple solid-liquid separation. The method of adding an acid and then processing to generate an aluminum phosphate phase can also obtain a high internal extraction rate. The extraction rate of lithium element can reach more than 93%, and the obtained lithium-containing product has high purity;

(2) The method for extracting lithium from lithium apatite and preparing iron-containing phosphate provided in the present application can also reuse aluminum phosphate precipitation to generate high-purity iron phosphate and / or ferrous phosphate, the phosphoric acid The purity of iron and / or ferrous phosphate can reach more than 95% (mass fraction), and the iron phosphate and / or ferrous phosphate can be used for preparing lithium iron phosphate.

After reading and understanding the detailed description and drawings, other aspects will become apparent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flowchart of a method for extracting lithium from lithium phosphite and preparing an iron-containing phosphate provided in Example 1 of the present application; FIG.

FIG. 2 is a schematic flowchart of a method for extracting lithium from lithium phosphite and preparing an iron-containing phosphate provided in Example 5 of the present application.

detailed description

In order to better explain the present application and facilitate understanding of the technical solution of the present application, the present application is further described in detail below. However, the following embodiments are merely simple examples of the present application, and do not represent or limit the scope of protection of the right of the present application. The scope of protection of the present application is subject to the claims.

The following are typical but non-limiting examples of this application:

Example 1

In this embodiment, lithium is extracted from lithium apatite and iron-containing phosphate is prepared according to the following method:

(1) Grinding and crushing the wollastonite, and then firing the wollastonite at 900 ° C. for 3 h in an air atmosphere to generate an aluminum phosphate phase. Mix the mass ratio of the roasted wollastonite and ammonium sulfate at 1: 0.4. Lithium was dissolved out, the mixing temperature was 150 ° C., and the mixing time was 3 h to obtain an eluent; the roasting was performed in a muffle furnace;

(2) The eluate in step (1) is filtered and separated to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate. After adding ethanol to the lithium-containing solution, a solid is taken, and the solid is redissolved in water to obtain a purified solution. A lithium-containing solution (the solute is lithium sulfate); the lithium-containing solution is evaporated, and a lithium sulfate solid can be obtained after removing the solvent.

(3) leaching the concentrated aluminum phosphate-containing precipitate in step (2) with concentrated nitric acid (mass content of nitric acid of 68 wt%), and then adding ferric chloride to the leaching solution; adding ammonia water dropwise at a rate of 1 mL / min to adjust the pH to 2 The mixture was stirred and mixed, and then separated by filtration to obtain iron phosphate.

A schematic flowchart of this embodiment is shown in FIG. 1.

The proportion of each component in the hectorite used in this example is shown in Table 1.

Table 1

ICP was used to analyze the lithium-containing solution, and ICP was used to analyze the iron phosphate (the iron phosphate was prepared into a solution). As a result, the extraction rate of lithium element in the lithium apatite was 95%; the concentration of lithium sulfate in the lithium-containing solution It is 25 g / L, and the total concentration of other impurities is less than 0.1 g / L. The purity of iron phosphate is 96.8%.

Example 2

(1) Grinding and crushing hectorite, and then firing the hectorite at 600 ° C for 6 h in an air atmosphere to produce an aluminum phosphate phase. The calcined hectorite and hydrochloric acid are mixed at a mass ratio of 1: 0.3. Lithium is dissolved out, the mixing temperature is 20 ° C., and the mixing time is 5 h to obtain an eluate; the roasting is performed in a muffle furnace;

(2) The eluate in step (1) is filtered and separated to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate, and the lithium-containing solution is subjected to precipitation and impurity purification to obtain a purified lithium-containing solution (the solute is chlorine Lithium); the lithium-containing solution is evaporated, and a lithium chloride solid can be obtained after removing the solvent.

(3) leaching the aluminum phosphate-containing precipitate in step (2) with concentrated hydrochloric acid (hydrochloric acid mass fraction of 20% by weight), and then adding ferrous chloride to the leaching solution, and adding sodium hydroxide dropwise at a rate of 0.1 mL / min The pH was adjusted to 1 and the mixture was stirred and mixed, and then filtered to obtain ferrous phosphate.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and ferrous phosphate. As a result, the extraction rate of the lithium element in the lithium-phospatite was 94%; the lithium chloride concentration in the lithium-containing solution was 27 g / L, and other impurities The sum of the concentrations is below 0.3 g / L; the purity of ferrous phosphate is 95.5%.

Example 3

(1) Sieving and crushing the lithium aluminite, and then firing the lithium apatite in a nitrogen atmosphere at 1100 ° C for 0.1 h to generate an aluminum phosphate phase. The mass ratio of the calcined lithium apatite to nitric acid is 1: 0.5. Mixing to dissolve lithium, the mixing temperature is 300 ° C., and the mixing time is 13 h to obtain an eluate; the roasting is performed in a tube furnace;

(2) The eluate in step (1) is filtered and separated to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate. After adding acetone to the lithium-containing solution, a solid is taken and the solid is redissolved in water to obtain a purified solution. Lithium-containing solution (the solute is lithium sulfate); the lithium-containing solution is subjected to crystallization and separation, and the lithium nitrate solid can be obtained after removing the solvent.

(3) leaching the concentrated aluminum phosphate-containing precipitate in step (2) with concentrated nitric acid (mass content of nitric acid of 70% by weight), and then adding ferric sulfate and ferrous sulfate at a mass ratio of 1: 1 to the leach solution at 2 mL / Aqueous ammonia was added dropwise at a rate of min to adjust the pH to 1, and the mixture was stirred and mixed, and then filtered and separated to obtain iron phosphate.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and the mixture of iron phosphate and ferrous phosphate. As a result, the extraction rate of lithium element in the lithium apatite was 94%; the concentration of lithium nitrate in the lithium-containing solution was 26 g / L, the total concentration of other impurities is below 0.2g / L; the total purity of the iron phosphate and ferrous phosphate in the mixture of iron phosphate and ferrous phosphate is 96.0%.

Example 4

(1) Sieving and crushing the lithium phospatite, and then calcining the lithium phospatite for 1 h in a nitrogen atmosphere to produce an aluminum phosphate phase, and mixing the calcined lithium phospatite and phosphoric acid at a ratio of 1: 0.5 Lithium is dissolved out, the mixing temperature is 150 ° C., and the mixing time is 3 h to obtain an eluate; the roasting is performed in a tube furnace;

(2) The eluate in step (1) is filtered and separated to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate. After adding acetone to the lithium-containing solution, a solid is taken and the solid is redissolved in water to obtain a purified solution. Lithium-containing solution (the solute is lithium phosphate); the lithium-containing solution is crystallized and separated, and a lithium phosphate solid can be obtained after removing the solvent.

(3) leaching the concentrated aluminum phosphate-containing precipitate in step (2) with concentrated nitric acid (mass content of nitric acid of 70% by weight), and then adding ferric sulfate and ferrous sulfate at a mass ratio of 1: 1 to the leach solution at 2 mL / Aqueous ammonia was added dropwise at a rate of min to adjust the pH to 3, followed by stirring and mixing, and then filtered and separated to obtain iron phosphate.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and the mixture of iron phosphate and ferrous phosphate. As a result, the extraction rate of lithium element in lithium apatite was 95%; the concentration of lithium phosphate in the lithium-containing solution was 25 g / L, the total concentration of other impurities is below 0.2g / L; the total purity of the iron phosphate and ferrous phosphate in the mixture of iron phosphate and ferrous phosphate is 96.0%.

Example 5

(1) Blend lithium hepatite and hydrochloric acid at a mass ratio of 1: 0.4, and then roast the resulting mixture at 800 ° C in an air atmosphere. The temperature rise rate of the roasting is 2 ° C / min, and the roasting time is 3h. The aluminum phosphate phase is calcined in a muffle furnace. After calcination, the lithium apatite is ground and crushed, and then water is added to dissolve lithium to obtain an eluate;

(3) leaching the aluminum phosphate-containing precipitate in step (2) with concentrated hydrochloric acid (hydrochloric acid mass fraction of 20% by weight), and then adding ferrous chloride to the leaching solution, and adding sodium hydroxide dropwise at a rate of 1 mL / min to adjust The pH was adjusted to 2 and the mixture was stirred and then separated by filtration to obtain ferrous phosphate.

A schematic flowchart of this embodiment is shown in FIG. 2.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and ferrous phosphate. As a result, the extraction rate of lithium element in the lithium phosphite was 94.6%; the concentration of lithium chloride in the lithium-containing solution was 25 g / L, and other impurities The sum of the concentrations is below 0.1 g / L; the purity of ferrous phosphate is 96.3%.

Example 6

(1) The mixture of hectorite and nitric acid is in a mass ratio of 1: 0.3, and the resulting mixture is roasted at 600 ° C in an air atmosphere. The temperature rise rate of the roasting is 0.5 ° C / min, and the roasting time is 6h. The aluminum phosphate phase is calcined in a muffle furnace. After calcination, the lithium apatite is ground and crushed, and then ethanol is added to dissolve lithium to obtain a dissolution liquid;

(2) The eluate in step (1) is filtered and separated to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate. The lithium-containing solution is subjected to precipitation and impurity purification to obtain a purified lithium-containing solution (the solute is nitric acid). Lithium); performing lithium carbide precipitation on the lithium-containing solution, and removing lithium carbonate to obtain a lithium carbonate solid.

(3) leaching the aluminum phosphate-containing precipitate in step (2) with concentrated nitric acid (mass content of nitric acid of 70 wt%), and then adding ferric chloride to the leaching solution, and adding sodium hydroxide dropwise at a rate of 1 mL / min to adjust the pH To 2 and stirred and mixed, and then separated by filtration to obtain iron phosphate.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and iron phosphate. As a result, the extraction rate of lithium element in lithium apatite was 93.5%; the concentration of lithium nitrate in the lithium-containing solution was 26 g / L, and the concentration of other impurities The sum is below 0.2g / L; the purity of iron phosphate is 96.8%.

Example 7

(1) Blend lithium hepatite and sulfuric acid at a mass ratio of 1: 0.36, and then roast the resulting mixture at 600 ° C in an air atmosphere. The temperature rise rate of the roasting is 5 ° C / min, and the roasting time is 6h. The aluminum phosphate phase is calcined in a muffle furnace. After calcination, the lithium apatite is ground and crushed, and then deionized water is added to dissolve lithium to obtain an eluate;

(2) filtering and separating the eluate from step (1) to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate, and adding impurities to the lithium-containing solution to obtain a purified lithium-containing solution (the solute is lithium nitrate); Sodium hydroxide was added to the lithium-containing solution, concentrated by evaporation, and dried to obtain a lithium hydroxide solid.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and iron phosphate. As a result, the extraction rate of lithium element in the lithium apatite was 94%; the total concentration of other impurities was less than 0.2g / L; the purity of the iron phosphate was 96.8%.

Example 8

(1) Mixing lithium hepatite and phosphoric acid at a mass ratio of 1: 0.5, and baking the obtained mixture at 1100 ° C in an argon atmosphere, the heating rate of the baking is 5 ° C / min, and the baking time is 0.1 h generates aluminum phosphate phase, roasting is carried out in a tube furnace, sieving and crushing the lithium phospatite, and adding water to dissolve lithium to obtain an eluate;

(2) The eluate in step (1) is filtered and separated to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate, and the lithium-containing solution is subjected to precipitation and impurity purification to obtain a purified lithium-containing solution (the solute is phosphoric acid) Lithium); The lithium-containing solution is evaporated, and a lithium phosphate solid can be obtained after removing the solvent.

(3) leaching the aluminum phosphate-containing precipitate in step (2) with concentrated hydrochloric acid (hydrochloric acid mass fraction of 20% by weight), and then adding ferrous chloride to the leaching solution, and adjusting by adding potassium hydroxide dropwise at a rate of 1 mL / min The pH was adjusted to 2 and the mixture was stirred and then separated by filtration to obtain ferrous phosphate.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and ferrous phosphate. As a result, the extraction rate of lithium element in the lithium-phospatite was 94.3%; the concentration of lithium chloride in the lithium-containing solution was 27 g / L, and other impurities The sum of the concentrations is below 0.3 g / L; the purity of ferrous phosphate is 97.1%.

Example 9

(1) Grinding and breaking the lithium apatite, followed by microwave induction. The microwave-induced microwave power is 600 W, and the microwave-induced time is 40 minutes to generate an aluminum phosphate phase. The microwave-induced lithium apatite and ammonium sulfate are 1: Mix at a mass ratio of 0.4 to dissolve lithium, the mixing temperature is 150 ° C., and the mixing time is 3 h to obtain an eluate; the roasting is performed in a muffle furnace;

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and ferrous phosphate. As a result, the extraction rate of lithium element in the lithium-phospatite was 94.5%; the concentration of lithium sulfate in the lithium-containing solution was 25 g / L. The total concentration is below 0.12g / L; the purity of iron phosphate is 96.2%.

Example 10

(1) Grinding and breaking lithium hepatite, followed by microwave induction. The microwave-induced microwave power is 700 W, and the microwave induction time is 30 minutes to generate an aluminum phosphate phase. The microwave-induced hepatite and ammonium sulfate are 1: Mix at a mass ratio of 0.4 to dissolve lithium, the mixing temperature is 150 ° C., and the mixing time is 3 h to obtain an eluate; the roasting is performed in a muffle furnace;

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and ferrous phosphate. As a result, the extraction rate of lithium element in the lithium-phospatite was 94.7%; the concentration of lithium sulfate in the lithium-containing solution was 25 g / L. The total concentration is below 0.11 g / L; the purity of iron phosphate is 96.3%.

Example 11

The specific method of this embodiment is referred to Example 1, and the difference is that in step (3), the pH is adjusted to 4.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and iron phosphate. As a result, the extraction rate of lithium element in the lithium apatite was 95%; the concentration of lithium sulfate in the lithium-containing solution was 25 g / L. The total concentration is below 0.1g / L; the purity of iron phosphate is 90%, which contains more aluminum phosphate impurities.

Example 12

The specific method of this embodiment is referred to Example 1, and the difference is that in step (3), the pH is adjusted to 0.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and iron phosphate. As a result, the extraction rate of lithium element in the lithium apatite was 95%; the concentration of lithium sulfate in the lithium-containing solution was 25 g / L. The total concentration is below 0.1 g / L; the purity of iron phosphate is 96.3%, but the output of iron phosphate in this embodiment is small, and the industrial utilization value is poor.

Example 13

The specific method of this embodiment is referred to Example 4, with the difference that, in step (1), the heating rate of the roasting is 10 ° C / min.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and ferrous phosphate. As a result, the extraction rate of lithium element in the lithium phosphite was 88.5%; the concentration of lithium chloride in the lithium-containing solution was 25 g / L, and other impurities The sum of the concentrations is below 0.8g / L; the purity of ferrous phosphate is 92.3%.

Example 14

The specific method of this embodiment is referred to Example 1, and the difference is that in step (1), the mixing temperature is 500 ° C.

The hectorite used in this example is the same as in Example 1.

The method of Example 1 was used to analyze the lithium-containing solution and ferrous phosphate. As a result, the extraction rate of lithium element in the lithium-phospatite was 95%; the concentration of lithium sulfate in the lithium-containing solution was 25 g / L. The total concentration is below 5g / L, and there are many impurities; the purity of iron phosphate is 96.8%.

Example 15

After the iron phosphate prepared in Example 1 was mixed with lithium carbonate, it was sintered at 720 ° C for 16 hours under the protection of nitrogen to obtain a lithium iron phosphate cathode material.

A coin cell made of a lithium iron phosphate positive electrode material was subjected to a charge and discharge test. The first discharge capacity was 153 mAh / g at 0.2C.

Example 16

After the iron phosphate prepared in Example 1 was mixed with lithium carbonate and a carbon source by ball milling, it was sintered at 730 ° C for 16 hours under a nitrogen atmosphere to obtain a carbon-coated lithium iron phosphate.

The obtained carbon-coated lithium iron phosphate material has a first discharge capacity of 159mAh / g at 0.2C

Example 17

The lithium nitrate, iron oxide, ammonium dihydrogen phosphate, and carbon source prepared in Example 3 were ball milled and mixed, and then sintered at 750 ° C for 20 hours under a nitrogen protective atmosphere to obtain a carbon-coated lithium iron phosphate cathode material.

The obtained lithium iron phosphate material had a first discharge capacity of 158 mAh / g under the condition of 0.2C.

Example 18

The lithium phosphate, ferric nitrate, phosphoric acid, and dopant prepared in Example 4 were added to the complexing agent, heated and stirred, and dried under vacuum after the reaction, and the particle size was refined to obtain a lithium iron phosphate precursor.

The lithium iron phosphate precursor was sintered at 780 ° C for 18 h under a nitrogen protective atmosphere, and oxygen-containing organic compounds and water vapor were passed during the sintering process to obtain lithium iron phosphate.

The obtained lithium iron phosphate material had a first discharge capacity of 160 mAh / g under the condition of 0.2C.

Example 19

The lithium carbonate prepared in Example 6 was mixed with a nickel-cobalt-manganese 523 precursor, and then sintered at 850 ° C. for 20 hours in an aerobic environment to obtain a nickel-cobalt-manganate 523 cathode material.

The prepared nickel-cobalt lithium manganate 523 cathode material has a first discharge capacity of 168 mAh / g under 0.2 C conditions.

Example 20

The lithium hydroxide prepared in Example 7 was mixed with a nickel-cobalt-aluminum precursor, and then sintered at 730 ° C. for 14 hours in an oxygen atmosphere to obtain a lithium-cobalt-aluminum-alumina positive electrode material.

The prepared nickel-cobalt lithium aluminate cathode material has a first discharge capacity of 198 mAh / g under the condition of 0.2C.

It can be known from the above embodiments that the method provided in the embodiments is simple in operation, short in process, low in cost, high in extraction rate of lithium element, high purity of the lithium-containing product obtained, and high purity of iron phosphate and / or ferrous phosphate. The excessively high pH value of step (3) in Example 11 caused a part of the aluminum phosphate to re-precipitate, resulting in a decrease in the purity of the iron phosphate product; the excessively low pH value of step (3) in Example 12 caused the extremely low yield of the iron phosphate product. The industrial utilization value is relatively poor; the temperature rising rate of the roasting in step (1) in Example 13 is too fast, which causes the acid to not completely react with the lithium apatite, which affects the extraction rate of lithium and the purity of the product; step (1) in Example 13 ) The mixing temperature is too high, which causes the concentration of impurities in the lithium-containing solution to be too high, which reduces the purity of lithium and increases the difficulty of subsequent processing. Examples 14-20 The lithium salt and ferric phosphate / ferrous phosphate prepared from the lithium apatite are used to further synthesize lithium iron phosphate and ternary positive electrode materials, and the prepared positive electrode materials have excellent electrochemical performance.

The applicant states that this application uses the foregoing embodiments to describe the detailed method of the application, but the application is not limited to the detailed method, which does not mean that the application must rely on the detailed method to be implemented.

Claims

A method for extracting lithium from hepatite and preparing an iron-containing phosphate, wherein the method includes the following steps:

(1) treating lithium phospatite to dissolve lithium to obtain an eluate;

(2) performing solid-liquid separation on the eluate in step (1) to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate;

(3) leaching the aluminum phosphate-containing precipitate in step (2) with an acid solution, adding an iron source to the leaching solution, adding an alkaline substance to adjust the pH, and then solid-liquid separation to obtain iron-containing phosphate.
The method according to claim 1, wherein in step (1), the method for treating lithium apatite to dissolve lithium includes the following steps: heat treating the lithium apatite to generate an aluminum phosphate phase, and Lithophosphasite is mixed with an acidic substance to dissolve lithium.
The method according to claim 1, wherein in step (1), the method for treating lithium apatite to dissolve lithium includes the steps of: mixing lithium apatite and an acidic substance, and performing the obtained mixture Heat treatment generates an aluminum phosphate phase. After the treatment, a solvent is added to dissolve lithium.
The method according to claim 2, wherein the method of heat treatment comprises roasting and / or microwave induction;

Optionally, the roasting temperature is 600-1100 ° C;

Optionally, the roasting time is 0.1-6h;

Optionally, the mass ratio of the calcined hectorite to the acidic substance is 1: (0.3-0.5);

Optionally, the firing atmosphere includes any one or a combination of at least two of air atmosphere, nitrogen atmosphere, argon atmosphere, helium atmosphere, or hydrogen atmosphere;

Optionally, the roasting is performed in a tube furnace or a muffle furnace;

Optionally, the microwave-induced microwave power is 500-700W;

Optionally, the microwave induction time is 30-50min;

Optionally, the mixing temperature is 20-300 ° C;

Optionally, the mixing time is 1-5h;

Optionally, the acidic substance includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid;

Optionally, before firing, the lithium phosphite is also crushed;

Optionally, the method of crushing includes grinding and / or sieving.
The method according to claim, wherein the acidic substance comprises any one or a combination of at least two of hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid;

Optionally, the mass ratio of the lithium apatite to the acidic substance is 1: (0.3-0.5);

Optionally, the heat treatment method includes roasting and / or microwave induction;

Optionally, the roasting temperature is 600-1100 ° C;

Optionally, the heating rate of the roasting is 0.5-5 ° C / min;

Optionally, the roasting time is 0.1-6h;

Optionally, the firing atmosphere includes any one or a combination of at least two of air atmosphere, nitrogen atmosphere, argon atmosphere, helium atmosphere, or hydrogen atmosphere;

Optionally, the roasting is performed in a tube furnace or a muffle furnace;

Optionally, the microwave-induced microwave power is 500-700W;

Optionally, the microwave induction time is 30-50min;

Optionally, the solvent includes any one or a combination of at least two of water, ethanol, methanol, propanol, or hexane, and may be water;

Optionally, before the solvent is added after calcination, the lithium apatite is further crushed;

Optionally, the method of crushing includes grinding and / or sieving.
The method according to any one of claims 1-5, wherein in step (2), the method for solid-liquid separation comprises filtration and / or centrifugation;

Optionally, step (2) further includes: purifying the lithium-containing solution;

Optionally, the purification method includes any one or a combination of at least two of extraction, crystallization, or precipitation removal;

Optionally, in step (2), the method further includes: performing solvent removal on the lithium-containing solution to obtain a lithium-containing solid product; and optionally, the method for removing the solvent includes evaporating the solvent, crystallizing, or precipitating lithium in lithium carbide. Any one or a combination of at least two.
The method according to any one of claims 1-6, wherein in step (3), the acid solution comprises a nitric acid solution and / or a hydrochloric acid solution;

Optionally, when the acid solution is a nitric acid solution, the mass fraction of the solute in the nitric acid solution is ≥68 wt%;

Optionally, when the acid solution is a hydrochloric acid solution, the mass fraction of the solute in the hydrochloric acid solution is ≧ 20% by weight.
The method according to any one of claims 1 to 7, wherein in step (3), the iron source comprises iron oxide, ferrous oxide, ferric chloride, ferrous chloride, ferric sulfate, ferrous sulfate Any one or a combination of at least two of iron nitrate, ferrous nitrate, ferric carbonate or ferrous carbonate;

Optionally, in step (3), the alkaline substance includes any one or a combination of at least two of ammonia water, sodium hydroxide, or potassium hydroxide.
The method according to any one of claims 1 to 8, wherein in step (3), the alkaline substance is a solution of an alkaline substance;

Optionally, in step (3), the method for adding the basic substance is dropwise addition;

Optionally, the dropping speed is 0.1-2 mL / min;

Optionally, in step (3), adjust the pH to a pH value of 1-3, optionally 2;

Optionally, in step (3), the pH is adjusted with stirring and mixing;

Optionally, in step (3), the solid-liquid separation includes filtration separation and / or centrifugation;

Optionally, in step (3), the iron-containing phosphate includes iron phosphate and / or ferrous phosphate;

Optionally, the iron phosphate and / or ferrous phosphate is used for preparing lithium iron phosphate.
The method according to any one of claims 1-9, wherein the method comprises the following steps:

(1) Crushing the wollastonite, and then firing the wollastonite at 600-1100 ° C in an air atmosphere for 0.1-6h. The roasted wollastonite and the acidic substance are in a mass of 1: (0.3-0.5). Than mixing to dissolve lithium, the mixing temperature is 20-300 ° C, and the mixing time is 1-5h to obtain an eluate;

(2) filtering and separating the eluate in step (1) to obtain a lithium-containing solution and an aluminum phosphate-containing precipitate, and purifying the lithium-containing solution to obtain a purified lithium-containing solution;

(3) leaching the aluminum phosphate-containing precipitate in step (2) with an acid solution, and then adding an iron source to the leaching solution; adding alkaline substances dropwise at a rate of 0.1-2 mL / min to adjust the pH to 2 and stirring and mixing, Thereafter, it is separated by filtration to obtain iron phosphate and / or ferrous phosphate.