Method for lithium extraction from lithium-bearing silicate minerals and by-product porous nanosilica

Abstract

The application discloses a method for extracting lithium from lithium-containing silicate minerals and by-product porous nanosilica, and the method comprises the following steps: (1) mixing the lithium-containing silicate minerals with a first metal inorganic salt, and ball milling the mixture; (2) performing acid activation on the ball-milling product and an acid solution under high-temperature and pressurized conditions, and performing solid-liquid separation to obtain an acid leaching solution and a first solid; obtaining porous nanosilica from the first solid; (3) mixing the acid leaching solution with any one or more than two of a second metal inorganic salt, a metal oxide and a natural mineral, adding the mixture into a container containing water, stirring and controlling pH, and stirring for a time under temperature rising, and then aging, inducing crystallization of metal ions in the acid leaching solution, and performing solid-liquid separation to obtain a lithium-rich solution and a second solid; and (4) obtaining a layered double hydroxide from the second solid. According to the method, lithium and other metal ions can be separated from the lithium-containing silicate minerals simultaneously, the lithium extraction rate is high, and the elements contained in the lithium-containing silicate minerals can be extracted and fully utilized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium extraction, and particularly relates to a method for extracting lithium from lithium silicate minerals and producing porous nanosilica as a byproduct. BACKGROUND

[0002] Lithium is a lightweight and highly active metal element, widely used in traditional fields such as batteries, glass ceramics, petroleum chemical industry, metallurgy, textiles, synthetic rubber, lubricating materials, medical treatment, etc., and also a key raw material for emerging fields such as new energy vehicles and energy storage systems. With the global pursuit of clean energy and sustainable development, the demand for lithium is increasing, especially in the field of lithium-ion batteries, the demand for lithium has surged, driving the development of lithium resources and the progress of lithium extraction technology.

[0003] Lithium extraction technology from lithium ore can be mainly divided into two categories: salt lake lithium extraction and ore lithium extraction. Salt lake lithium extraction technology utilizes lithium resources in salt lakes and extracts lithium through physical and chemical methods, including precipitation method, solar pond method, extraction method, calcination method, adsorption method, etc. Ore lithium extraction technology mainly adopts fire method and wet method, which is mainly to destroy the mineral structure and leach out lithium. Among them, the fire method includes limestone method, sulfate method, chloride method, etc., and the wet method includes soda pressure leaching method, alkali dissolution method, etc.

[0004] At present, the industrial lithium extraction process is mainly to roast lithium-containing minerals at high temperature, and then add acid, salt roasting or alkali pressure cooking method, which generally involves the use of concentrated sulfuric acid, sulfate, fluoride and other reagents, with the characteristics of high energy consumption, environmental unfriendliness, low resource utilization rate, large amount of slag, etc. In the industrial lithium extraction process, the tailings after lithium extraction are often discarded as "solid waste", but in fact, the slag still contains a large amount of silicon, aluminum and other elements derived from the structure of lithium ore.

[0005] At present, the methods for extracting lithium from lepidolite include sulfate method, high-pressure alkali cooking method, sulfuric acid method, chloride salt method and mechanical activation method. For example, Chinese patent document CN106755967A proposes a method for treating lepidolite by sulfuric acid calcination to produce lithium carbonate, which converts lithium in lepidolite into soluble lithium sulfate by sulfuric acid roasting; for example, Chinese patent document CN106745097A proposes a method for treating lepidolite by sulfate roasting, which converts lithium in lepidolite into soluble lithium sulfate by high-temperature sulfate roasting; for example, Chinese patent document CN105907943A proposes a method for treating lepidolite by chloride roasting, which converts lithium in lepidolite into soluble lithium chloride by high-temperature chloride roasting; for example, Chinese patent document CN108163874A proposes a method for treating lepidolite by hydrothermal treatment, which converts lithium in lepidolite into soluble lithium hydroxide by high-temperature hydrothermal treatment. Although these methods achieve effective extraction of lithium from lepidolite, they generally have the problems of high energy consumption, large amount of slag, and low leaching rate.

[0006] Chinese patent document CN115747520B discloses a method for extracting lithium from lithium-containing ore, comprising the following steps: (1) the lithium-containing ore is subjected to acid treatment to obtain a lithium-containing acidified liquid; (2) the lithium-containing acidified liquid is subjected to initial filtration treatment, nanofiltration treatment and ion exchange treatment in sequence to obtain a lithium-containing concentrated liquid; the ion exchange resin used in the ion exchange treatment comprises a chelating resin with N as the coordination atom; (3) the lithium-containing concentrated liquid is subjected to sodium removal treatment to obtain a lithium chloride product. However, the lithium yield of multiple embodiments of this patent is only 52.5-88.5%, and since cation exchange resin is used, the resin needs to be regenerated frequently when the ion exchange load is high, and the treatment of waste residue after lithium extraction from lithium-containing ore is not involved.

[0007] Chinese patent document CN114350978A discloses a method for extracting lithium from lithium-containing clay in steps, comprising the following steps: S1, mixing uncalcined lithium-containing clay with acid and reacting under a pressure of 1.5 MPa;

[0008] S2, performing solid-liquid separation on the product after the reaction of step S1 to obtain filtrate and filter residue, and washing the filter residue; S3, mixing the filter residue after washing of step S2 with acid and reacting under a pressure of 1.5 MPa; S4, performing solid-liquid separation on the product after the reaction of step S3 to obtain filtrate and filter residue, and then collecting the filtrate. However, this patent involves two-stage high-pressure acid washing, which has high energy consumption, complicated steps, and general comprehensive lithium extraction rate, and the treatment and utilization of filter residue are not considered subsequently. SUMMARY

[0009] The purpose of the present application is to provide a method for extracting lithium from lithium-containing silicate minerals and by-product porous nanosilica, aiming to solve the problems of high energy consumption, environmental unfriendliness, large amount of residue and low resource utilization efficiency in the existing lithium ore extraction process. The method is simple and effective, realizes the comprehensive utilization of resources, and provides a new idea for the high-value utilization of lithium-containing silicate minerals.

[0010] In order to achieve the above purpose, the present application provides a method for extracting lithium from lithium-containing silicate minerals and by-product porous nanosilica, which comprises the following steps:

[0011] (1) mixing lithium-containing silicate minerals with a first metal inorganic salt, and ball milling the mixture; wherein the first metal inorganic salt is selected from any one or two or more of sodium chloride, magnesium chloride, aluminum chloride, calcium chloride, sodium nitrate, magnesium nitrate, calcium nitrate, aluminum nitrate, sodium sulfate and magnesium sulfate;

[0012] (2) subjecting the ball milling product to acid activation under high-temperature and high-pressure conditions with an acid solution, and performing solid-liquid separation to obtain an acid leaching liquid and a first solid; washing and drying the first solid to obtain porous nanosilica;

[0013] (3) mixing any one or more than two of the second metal inorganic salt, metal oxide and natural mineral with the acid leaching solution, adding the alkali solution into water, stirring and controlling pH, stirring for a time at elevated temperature, then aging, inducing the crystallization of metal ions in the acid leaching solution, and solid-liquid separation to obtain a lithium-rich solution and a second solid;

[0014] (4) washing and drying the second solid to obtain a layered double hydroxide.

[0015] The method of the present application mixes the lithium-containing silicate mineral with the metal inorganic salt, and acid-activates the mixture under high temperature and pressure conditions. Under this condition, the Al, Mg and Fe metal cations in the octahedron of the lithium-containing silicate mineral can be effectively dissolved using low concentration of hydrogen ions. The metal ions contained in the added metal inorganic salt have the effect of promoting the dissolution of the mineral, thereby destroying the structure of the mineral and making the lithium in the mineral more easily dissolved. The main roles of the metal inorganic salt include: (1) serving as a grinding medium to strengthen the destruction of the mineral structure by grinding and improve the grinding efficiency; (2) hydrating the inorganic ions to open the mineral structure from the micro-cracks and lamellar end faces of the mineral surface, causing the lamellar to rise and generate more cracks, increasing the probability of the attack of protons on the mineral structure ions, and promoting the dissolution of the mineral; (3) the metal ions compete with the dissolved lithium ions for the adsorption sites on the mineral surface, reducing the adsorption of lithium ions; (4) providing layer plate ions in the preparation of the layered double hydroxide, adjusting the crystal form of the layered double hydroxide, etc. The first solid obtained by solid-liquid separation after acid activation is washed with water to neutral pH and dried to obtain porous nanosilica. The acid leaching solution is rich in metal ions such as Al 3+ , Mg 2+ , Fe 3+ , etc. The alkali, metal inorganic salt or natural mineral is added to the acid leaching solution, such as the preparation of magnesium-aluminum layered double hydroxide, which is generally added to n(Mg 2+ ):n(Al 3+ )=(2-4):1. Too high or too low will affect the crystal form and crystallinity of the hydrotalcite. The pH is adjusted and the metal ions are supplemented to adjust the molar ratio of the metal ions, induce the crystallization and precipitation of the metal ions in the acid leaching solution, and achieve the purpose of solid-liquid separation. The lithium-rich acid leaching solution and the second solid are obtained after solid-liquid separation, and then the second solid is washed with water to neutral pH and dried. The lithium-rich acid leaching solution contains the first and second metal inorganic salts added before, and the salinity will affect the crystallinity, grain size and morphology of the layered double hydroxide prepared subsequently. The content of other metal ions in the lithium-rich acid leaching solution is low, which is beneficial to the further separation of lithium.

[0016] The first metal inorganic salt used in the present application contains metal ions that promote the dissolution / conversion of the mineral. For example, Na +After entering the interlayer of the mineral, the expandable sheet layer is formed, the interlayer channel is opened, and the dissolution of the sheet structure is promoted; Al 3+ Not only can it enter the interlayer of the layered silicate mineral in the form of ions or polyions, open the interlayer channel, and promote the further dissolution of the sheet layer; but also can participate in the formation of secondary minerals, reduce the local ion concentration, and promote the dissolution of the matrix mineral elements; and by Al 3+ Hydrolysis provides a large number of hydrogen ions, reduces the pH of the system, and thus destroys the structure of the mineral. Similarly, Mg 2+ and Ca 2+ Can obtain similar effects in the system.

[0017] The method of the present application has high lithium extraction rate, simple and efficient method, low energy consumption, and realizes the comprehensive utilization of elements, and the products include lithium salt, porous nanosilica, layered double hydroxide, which greatly improves the economic benefit, and the whole process does not produce tailings, avoiding the pollution to the environment.

[0018] Preferably, in step (1), the lithium-containing silicate mineral is selected from any one or two or more of spodumene, petalite, eucryptite, lepidolite, iron lepidolite, hectorite, lithium kaolinite, lithium illite, saponite, lithium chlorite, lithium zeolite and jadarite. The lithium-containing silicate mineral used in the present application has abundant reserves and low cost.

[0019] Preferably, in step (1), the mass ratio of the lithium-containing silicate mineral to the first metal inorganic salt is 1:(0.1-10).

[0020] Preferably, in step (1), the rotation speed of the ball mill is 300-900 rpm, and the time is 1-10 h.

[0021] Preferably, in step (2), the acid solution, the acid is selected from any one or two or more of hydrochloric acid, nitric acid, phosphoric acid, formic acid, acetic acid and oxalic acid; the concentration of the acid solution is at least 0.01 mol / L.

[0022] Preferably, in step (2), the high-temperature and high-pressure conditions, the temperature is 60-240℃, the pressure is 0.2-2.0 MPa, the filling rate of the container is 10-80%, and the time is 2-48 h.

[0023] Preferably, in step (2), the high-temperature and high-pressure conditions, the temperature is 130-180℃, the pressure is 0.2-2.0 MPa, the filling rate of the container is 30-70%, and the time is 16-24 h.

[0024] Preferably, in step (2), the drying temperature of the first solid is 60-120℃.

[0025] More preferably, in step (2), the drying temperature of the first solid is 70-100℃.

[0026] Preferably, in step (3), the second metal inorganic salt is selected from any one or two or more of magnesium nitrate, zinc nitrate, aluminum nitrate, iron nitrate, calcium nitrate, chromium nitrate, lanthanum nitrate, magnesium chloride, iron chloride, aluminum chloride, calcium chloride, sodium carbonate, sodium bicarbonate, sodium sulfate, magnesium sulfate, iron sulfate and aluminum sulfate; or / and, the alkali solution, the alkali is selected from metal hydroxide; or / and, the natural mineral is selected from at least one of dolomite, limestone, magnesite and calcite; or / and, the pH is 7-13.

[0027] More preferably, in step (3), the alkali solution, the alkali is selected from any one or two or more of potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, iron hydroxide, nickel hydroxide, cobalt hydroxide and barium hydroxide.

[0028] Preferably, in step (3), the temperature is increased to 60-150℃ for 2-3h; or / and, the aging temperature is 75-120℃ for 2-18h.

[0029] More preferably, in step (3), the temperature is increased to 75-120℃ for 2-3h.

[0030] The method for extracting lithium from lithium-containing silicate minerals and by-product porous nanosilica according to the present application has the following advantages:

[0031] (1) The present application uses acid to activate lithium-containing silicate minerals, and a large amount of insoluble substances are not generated in the process, and lithium, magnesium, aluminum, iron and other elements are dissolved in hydrochloric acid into the solution, and the remaining solid is porous nanosilica. By inducing metal ion crystallization and separation, magnesium, aluminum and other metal elements are precipitated to prepare layered double hydroxides, and the remaining liquid is a lithium-rich solution. This method realizes the comprehensive extraction of lithium, silicon, aluminum and other elements in lithium ore, greatly improving the economic benefit.

[0032] (2) The metal inorganic salt used in the present application has the following main functions: ① It acts as a grinding medium to strengthen the destruction of the mineral structure and improve the grinding efficiency; ② The hydrated inorganic ions can open the mineral structure from the microcracks and lamellar end face of the mineral surface, cause the lamellar to rise and generate more cracks, increase the probability of proton attacking the mineral structure ions, and promote the dissolution of the mineral; ③ The metal ions compete with the dissolved lithium ions for the adsorption sites on the mineral surface, thereby reducing the adsorption of lithium ions; and ④ In the preparation of layered double hydroxides, it provides layer plate ions to adjust the crystal form of the layered double hydroxides. Since it can provide different metal ions as layer plate ions, it can be used to prepare various layered double hydroxides with different properties and different uses. The lithium silicate mineral used in the present application has abundant reserves and low cost, and the lithium extraction rate is high. The method is simple, efficient, and low in energy consumption, and realizes the comprehensive utilization of elements. The products include lithium salt, porous nanosilica, and layered double hydroxide, which greatly improves the economic benefit. Moreover, the whole process does not produce tailings, avoiding environmental pollution.

[0033] (3) The method of the present application realizes the extraction of lithium from lithium silicate minerals, while leaching other metal elements in the minerals, and separates lithium from other metal ions by inducing metal ion crystallization. The obtained porous nanosilica has high purity, small particle size, large specific surface area, and high activity, and can be used in the fields of cosmetics, medicines, and coatings. The obtained layered double hydroxide can be used in the fields of catalysis, medicine, and adsorption. The method has high lithium extraction rate, is simple and effective, and is environmentally friendly, and extracts and fully utilizes the elements contained in the lithium silicate minerals. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The flow chart of the method for extracting lithium from lithium silicate minerals and obtaining porous nanosilica according to the present application.

[0035] Figure 2 The lithium extraction rate of the leaching solution of Example 1 and Example 2 of the present application.

[0036] Figure 3 The Mg / Li of the leaching solution of Example 1 and Example 2 of the present application.

[0037] Figure 4 The X-ray diffraction pattern of the porous nanosilica obtained in Example 1 of the present application.

[0038] Figure 5 The SEM picture of the porous nanosilica obtained in Example 1 of the present application.

[0039] Figure 6 The TEM picture of the porous nanosilica obtained in Example 1 of the present application.

[0040] Figure 7Nitrogen adsorption-desorption curve of the porous nanosilica obtained in Example 1 of the present application, Comparative Example 3.

[0041] Figure 8 TEM image of the magnesium-aluminum layered double hydroxide obtained in Example 1 of the present application.

[0042] Figure 9 X-ray diffraction pattern of the magnesium-aluminum layered double hydroxide obtained in Comparative Example 2 of the present application.

[0043] Figure 10 X-ray diffraction pattern of the magnesium-aluminum layered double hydroxide obtained in Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0045] It should be noted that, in the embodiments, the specific conditions not mentioned are carried out according to the conventional conditions or the conditions recommended by the manufacturers. The reagents or instruments not mentioned by the manufacturers are the conventional products that can be purchased in the market.

[0046] Example 1

[0047] The method for extracting lithium from lithium silicate minerals and by-product porous nanosilica comprises the following steps:

[0048] (1) 20 g of lepidolite and 20 g of sodium chloride were added into a maroon ball mill jar, the mass ratio of maroon ball to lepidolite was 10:1, and the mixture was ball milled at a speed of 350 rpm for 2 h, and then the lepidolite and sodium chloride mixture powder was collected;

[0049] (2) The ball milled product obtained in step (1) (i.e. the lepidolite and sodium chloride mixture powder) was transferred into a 1 L polytetrafluoroethylene jar, 400 mL of hydrochloric acid with a mass concentration of 18 wt.% (6 mol / L) was added, and after stirring, the polytetrafluoroethylene jar was placed in a stainless steel pressure-resistant reaction kettle, the pressure was 0.6 MPa, and the filling rate of the container was 40%. The reaction kettle was transferred into an oven, and heated to 180℃ for 2 hours. After cooling, the solid-liquid mixture in the polytetrafluoroethylene jar was taken out and suction filtered, and the solid was washed with water and dried at 60℃ to obtain porous nanosilica;

[0050] (3) Collect the acid leaching solution obtained in step (2), add 3.6786 g of MgO and 8.9206 g of dolomite to the acid leaching solution, and prepare another 400 mL of alkaline solution containing 1.9008 mol of NaOH and 0.3802 mol of Na2CO3. At room temperature, the acid leaching solution and the alkaline solution are added dropwise into the same beaker pre-filled with 268 mL of ultrapure water by a pH automatic liquid adding machine, and the mechanical stirring and constant pH (pH = 9 ± 0.2) are maintained. After the dropwise addition is completed, the beaker is transferred to a water bath pot and heated to 75°C, and the stirring is maintained for 3 hours, and then the aging is continued at 90°C in a drying box for 18 hours;

[0051] (4) After the aging is completed, the solid-liquid mixture in the beaker is centrifuged and washed with water for multiple times until the pH of the supernatant approaches neutral. The magnesium-aluminum layered double hydroxide is separated and dried to obtain a lithium-rich solution.

[0052] The lithium extraction rate of this example is 92.93%, the magnesium-lithium ratio of the lithium-rich solution is 0.30, and the specific surface area of the obtained porous nanosilica is 142.6 m 2 / g.

[0053] Example 2

[0054] The method for extracting lithium from lithium silicate minerals and producing porous nanosilica as a byproduct includes the following steps:

[0055] (1) 25 g of lepidolite and 5 g of sodium chloride are added to a maroon ball mill jar, and the mass ratio of maroon balls to lepidolite is 10:1. The lepidolite powder is collected after ball milling at a speed of 350 rpm for 2 h;

[0056] (2) The ball-milled product (i.e., the mixed powder of lepidolite and sodium chloride) obtained in step (1) is transferred to a 500 mL polytetrafluoroethylene tank, and 250 mL of sulfuric acid with a molar concentration of 6 mol / L is added. After stirring, the polytetrafluoroethylene tank is placed in a stainless steel pressure-resistant reaction kettle with a pressure of 1.0 MPa and a filling rate of the container of 50%. The reaction kettle is transferred into an oven and heated to 150°C for 24 hours. After cooling, the solid-liquid mixture in the polytetrafluoroethylene tank is taken out and filtered, and the solid is washed with water and dried at 120°C to obtain porous nanosilica;

[0057] (3) Collect the acid leaching solution obtained in step (2), add 22.6660 g of MgS04-7H20 to the acid leaching solution, and prepare another 250 mL of alkali solution containing 2.3760 mol of NaOH. At room temperature, the acid leaching solution and the alkali solution are added dropwise into the same beaker pre-filled with 167.5 mL of ultrapure water by a pH automatic liquid adding machine, and the mechanical stirring and constant pH (pH = 8 ± 0.2) are maintained. After the dropwise addition is completed, the beaker is transferred to a water bath pot and heated to 75°C, and the stirring is maintained for 3 hours, and then the aging is continued at 90°C in a drying box for 18 hours;

[0058] (4) After the aging is completed, the solid-liquid mixture in the beaker is centrifuged and washed with water for multiple times until the pH of the supernatant approaches neutral. The magnesium-aluminum layered double hydroxide is separated and dried to obtain a lithium-rich solution.

[0059] The lithium extraction rate of this example is 88.01%, the magnesium-lithium ratio of the lithium-rich solution is 0.32, and the specific surface area of the obtained porous nanosilica is 162.5 m 2 / g.

[0060] Example 3

[0061] The method for extracting lithium from lithium silicate minerals and by-product porous nanosilica includes the following steps:

[0062] (1) 25 g of spodumene (converted into β-type spodumene by calcination at 1100°C) and 25 g of anhydrous magnesium chloride are added to a maroon ball mill jar, the mass ratio of maroon ball to spodumene is 10:1, and the spodumene powder is collected after ball milling at a speed of 400 rpm for 3 h;

[0063] (2) The ball-milled product (i.e., the mixed powder of spodumene and anhydrous magnesium chloride) obtained in step (1) is transferred to a 500 mL polytetrafluoroethylene tank, 180 mL of sulfuric acid with a molar concentration of 6 mol / L and 70 mL of oxalic acid with a mass concentration of 50% are added, and after stirring, the polytetrafluoroethylene tank is placed in a stainless steel pressure-resistant reaction kettle with a pressure of 2.0 MPa and a filling rate of 50%. The reaction kettle is transferred into an oven and heated to 180°C for 48 hours. After cooling, the solid-liquid mixture in the polytetrafluoroethylene tank is taken out and filtered, and the solid is washed with water and dried at 80°C to obtain porous nanosilica;

[0064] (3) Collect the acid leaching solution obtained in step (2), and prepare another 150 mL of alkali solution containing 1.4256 mol of NaOH and 0.2851 mol of Na2CO3. At room temperature, the acid leaching solution and the alkali solution are added dropwise into the same beaker pre-filled with 100.5 mL of ultrapure water by using a pH automatic liquid adding machine, and the mechanical stirring and constant pH (pH = 10 ± 0.2) are maintained. After the dropwise addition is completed, the beaker is transferred to a water bath pot and heated to 90°C, and the stirring is maintained for 2 hours, and then the aging is continued at 120°C in a drying box for 16 hours;

[0065] (4) After the aging is completed, the solid-liquid mixture in the beaker is centrifuged and washed with water for multiple times until the pH of the supernatant approaches neutral. The magnesium-aluminum layered double hydroxide is separated and dried to obtain a lithium-rich solution.

[0066] The lithium extraction rate of this example is 92.71%, the magnesium-lithium ratio of the lithium-rich solution is 0.21, and the specific surface area of the obtained porous nanosilica is 85.4 m 2 / g.

[0067] Example 4

[0068] The method for extracting lithium from lithium silicate minerals and by-product porous nanosilica includes the following steps:

[0069] (1) 40 g of hectorite and 10 g of sodium chloride are added to a maroon ball mill jar, and the mass ratio of maroon ball to hectorite is 5:1. Ball milling is performed at a speed of 300 rpm for 2 h, and then the hectorite powder is collected;

[0070] (2) The ball milling product (i.e., the mixed powder of hectorite and sodium chloride) obtained in step (1) is transferred to a 500 mL polytetrafluoroethylene tank, 160 mL of hydrochloric acid with a molar concentration of 5 mol / L and 40 mL of acetic acid with a mass concentration of 30% are added, and after stirring, the polytetrafluoroethylene tank is placed in a stainless steel pressure-resistant reaction kettle with a pressure of 0.2 MPa and a filling rate of the container of 40%. The reaction kettle is transferred into an oven and heated to 130°C for 16 hours. After cooling, the solid-liquid mixture in the polytetrafluoroethylene tank is taken out and filtered, and the solid is washed with water and dried at 100°C to obtain porous nanosilica;

[0071] (3) Collect the acid leaching solution obtained in step (2), and add 35.37 g of Mg (NO3) 2·6H2O and 9.6445 g of Al (NO3) 3to the acid leaching solution. Prepare another 200 mL of alkali solution containing 1.9008 mol of NaOH and 0.3801 mol of Na2CO3. At room temperature, add the acid leaching solution and the alkali solution drop by drop into the same beaker pre-filled with 135 mL of ultrapure water through a pH automatic liquid adding machine, and keep the mechanical stirring and constant pH (pH = 11 ± 0.2). After the addition is completed, the beaker is transferred to a water bath pot and heated to 70℃, and the stirring is kept for 3 hours, and then the aging is continued at 90℃ in a drying box for 12 hours;

[0072] (4) After the aging is completed, the solid-liquid mixture in the beaker is centrifuged and washed with water for multiple times until the pH of the supernatant approaches neutral. The magnesium-aluminum layered double hydroxide is separated and dried to obtain a lithium-rich solution.

[0073] The lithium extraction rate of this example is 89.26%, the magnesium-lithium ratio of the lithium-rich solution is 0.69, and the specific surface area of the obtained porous nanosilica is 411.8 m 2 / g.

[0074] Example 5

[0075] The method for extracting lithium from lithium silicate minerals and producing porous nanosilica as a byproduct comprises the following steps:

[0076] (1) Put 20 g of hectorite and 10 g of calcium chloride into a maroon ball mill jar, and mill the mixture at a speed of 300 rpm for 2 h. Then collect the lithium illite powder;

[0077] (2) Transfer the ball-milled product (i.e., the mixture of hectorite and calcium chloride) obtained in step (1) into a 500 mL polytetrafluoroethylene tank, add 150 mL of hydrochloric acid with a molar concentration of 5 mol / L and 50 mL of formic acid with a mass concentration of 20%, and then stir the mixture. Place the polytetrafluoroethylene tank in a stainless steel pressure reactor with a pressure of 0.6 MPa and a filling rate of 40%. Transfer the reactor into an oven and heat it to 150℃ for 12 hours. After cooling, take out the solid-liquid mixture in the polytetrafluoroethylene tank and filter it. The solid is washed with water and dried at 90℃ to obtain porous nanosilica;

[0078] (3) Collect the acid leaching solution obtained in step (2), add 15.7600 g of limestone to the acid leaching solution, and prepare another 200 mL of alkali solution containing 2.2810 mol of NaOH and 0.4562 mol of Na2CO3. At room temperature, the acid leaching solution and the alkali solution are added dropwise into the same beaker pre-filled with 135 mL of ultrapure water by a pH automatic liquid adding machine, and the mechanical stirring and constant pH (pH = 10 ± 0.2) are maintained. After the dropwise addition is completed, the beaker is transferred to a water bath pot and heated to 70°C, and the stirring is maintained for 3 hours, and then the aging is continued in a drying box at 75°C for 12 hours;

[0079] (4) After the aging is completed, the solid-liquid mixture in the beaker is centrifuged and washed with water for multiple times until the pH of the supernatant approaches neutral. The calcium-aluminum layered double hydroxide is separated and dried to obtain a lithium-rich solution.

[0080] The lithium extraction rate of this example is 90.29%, the magnesium-lithium ratio of the lithium-rich solution is 0.81, and the specific surface area of the obtained porous nanosilica is 167.8 m 2 / g.

[0081] Example 6

[0082] The method for extracting lithium from lithium silicate minerals and by-product porous nanosilica includes the following steps:

[0083] (1) 20 g of lithium zeolite and 20 g of calcium chloride are added to a maroon ball mill jar, the mass ratio of maroon ball to lithium zeolite is 10:1, and the ball milling is performed at a speed of 350 rpm for 5 h, and then the lithium zeolite powder is collected;

[0084] (2) The ball-milled product (i.e., the mixed powder of lithium zeolite and calcium chloride) obtained in step (1) is transferred to a 500 mL polytetrafluoroethylene tank, 250 mL of hydrochloric acid with a molar concentration of 0.01 mol / L and 50 mL of formic acid with a mass concentration of 20% are added, after stirring, the polytetrafluoroethylene tank is placed in a stainless steel pressure-resistant reaction kettle, the pressure is 1.2 MPa, and the filling rate of the container is 60%. The reaction kettle is transferred into an oven and heated to 180°C for 8 hours. After cooling, the solid-liquid mixture in the polytetrafluoroethylene tank is taken out and filtered, and the solid is washed with water and dried at 80°C to obtain porous nanosilica;

[0085] (3) Collect the acid leaching solution obtained in step (2), add 12.0400 g of magnesite to the acid leaching solution, and prepare another 300 mL of an alkali solution containing 1.1841 mol of NaOH and 0.2652 mol of Na2CO3. At room temperature, the acid leaching solution and the alkali solution are added dropwise into the same beaker pre-filled with 135 mL of ultrapure water by means of a pH automatic liquid adding machine, and mechanical stirring and constant pH (pH = 10 ± 0.2) are maintained. After the dropwise addition is completed, the beaker is transferred to a water bath pot and heated to 70°C, and stirring is maintained for 3 hours, and then the aging is continued in a drying box at 75°C for 12 hours;

[0086] (4) After the aging is completed, the solid-liquid mixture in the beaker is centrifuged and washed with water for multiple times until the pH of the supernatant approaches neutrality. The calcium-aluminum layered double hydroxide is separated and dried, and the separated liquid is a lithium-rich solution.

[0087] The lithium extraction rate of this example is 90.29%, the magnesium-lithium ratio of the lithium-rich solution is 0.31, and the specific surface area of the obtained porous nanosilica is 224.7 m 2 / g.

[0088] Comparative Example 1

[0089] In this comparative example, the molar concentration of hydrochloric acid in step (2) of Example 1 is changed to 0.001 mol / L, and the rest is the same as Example 1. The lithium extraction rate of this comparative example is 62.71%, the magnesium-lithium ratio of the lithium-rich solution is 16.78, and the specific surface area of the obtained porous nanosilica is 42.72 m 2 / g.

[0090] Comparative Example 2

[0091] In this comparative example, the amount of sodium chloride in step (1) of Example 1 is increased from 20 g to 40 g, and the rest is the same as Example 1. The lithium extraction rate of this comparative example is 93.65%, the magnesium-lithium ratio of the lithium-rich solution is 0.42, and the specific surface area of the obtained porous nanosilica is 167.8 m 2 / g.

[0092] Comparative Example 3

[0093] In this comparative example, the sodium chloride in step (1) of Example 1 is removed, and direct pressure acid washing is performed, and the rest is the same as Example 1. The lithium extraction rate of this comparative example is 85.54%, the magnesium-lithium ratio of the lithium-rich solution is 0.73, and the specific surface area of the obtained porous nanosilica is 62.57 m 2 / g.

[0094] Comparative Example 4

[0095] The sodium chloride in step (1) of Example 6 was removed, and the solution was directly pressurized and pickled at a low acid concentration, and the rest was the same as in Example 6. The lithium extraction rate of this comparative example was 77.52%, the magnesium-lithium ratio of the lithium-rich solution was 0.21, and the specific surface area of ​​the obtained porous nano-silica was 55.48 m 2 / g.

[0096] Table 1 shows the composition of porous nano-silica obtained in various embodiments and comparative examples of the present invention.

[0097]

[0098]

[0099] Note: “-” indicates not detected.

[0100] As shown in Table 1, the proportions of various material components of the porous nano-silica obtained in each embodiment of the present invention are shown. Combining the various embodiments and comparative examples, when the acid treatment time is the same, the lower the acid concentration used, the lower the purity of the porous nano-silica obtained; when the acid concentration and acid treatment time are the same, the addition of metal inorganic salts can promote the dissolution of minerals and increase the specific surface area of ​​porous silica; at low acid concentrations (0.1 mol / L), the effect of inorganic salts in promoting mineral dissolution is more obvious, and the pores of silica obtained in the system without the addition of inorganic salts are underdeveloped. In addition, inorganic / organic composite acids can enhance the effect of acid treatment.

[0101] like Figure 2 As shown, the lithium extraction rate of the leachate of Example 1 and Example 2 of the present invention is about 90% when hydrochloric acid and sulfuric acid are used for pressure acid leaching.

[0102] like Figure 3 As shown, the Mg / Li ratio of the leachate of Example 1 and Example 2 of the present invention is very low, only 0.30, which is conducive to the further separation of lithium and other elements.

[0103] like Figure 4 , which is the X-ray diffraction pattern of the porous nano-silica obtained in Example 1 of the present invention, the phases of the product of pressurized acid leaching of lepidolite include amorphous silica and quartz.

[0104] like Figure 5 , which is a SEM picture of the porous nano-silica obtained in Example 1 of the present invention. The obtained porous nano-silica particles are formed by agglomeration of nanoparticles, and the particle size is relatively uniform.

[0105] like Figure 6 As shown, it is a TEM picture of the porous nano-silica obtained in Example 1 of the present invention. The obtained porous nano-silica particles are extremely small, only tens of nanometers, and have rich pore structures.

[0106] like Figure 7 As shown, there is a nitrogen adsorption / desorption curve of the silicon dioxide obtained in Example 1 of the present invention and Comparative Example 3. It can be seen that when other conditions are the same, the mineral dissolution of the system with the addition of metal inorganic salts is more efficient, and has a positive effect on the formation of the multi-level pore structure of silicon dioxide and the increase of specific surface area.

[0107] like Figure 8 , which is the X-ray diffraction pattern of the magnesium-aluminum layered double hydroxide obtained in Example 1 of the present invention. The characteristic diffraction peak of the magnesium-aluminum layered double hydroxide is relatively strong, indicating that its crystallization is relatively good.

[0108] like Figure 9 Shown is a TEM image of the magnesium-aluminum layered double hydroxide obtained in Example 1 of the present invention.

[0109] like Figure 10 As shown, this is the X-ray diffraction pattern of the magnesium-aluminum layered double hydroxide obtained in Comparative Example 2 of the present invention. When the salt concentration increases, the crystallinity of the magnesium-aluminum layered double hydroxide becomes significantly weaker, indicating that its grain growth is inhibited to a certain extent.

[0110] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for extracting lithium from lithium-containing silicate minerals and producing porous nano-silica as a by-product, characterized in that: The method comprises the following steps: (1) mixing a lithium-containing silicate mineral with a first metal inorganic salt, and ball-milling the mixture; wherein the first metal inorganic salt is selected from any one or more of sodium chloride, magnesium chloride, aluminum chloride, calcium chloride, sodium nitrate, magnesium nitrate, calcium nitrate, aluminum nitrate, sodium sulfate, and magnesium sulfate; (2) subjecting the ball milled product and an acid solution to acid activation under high temperature and pressure conditions, and separating the solid and liquid to obtain an acid leaching solution and a first solid; washing and drying the first solid to obtain porous nano-silica; (3) mixing any one or more of a second metal inorganic salt, a metal oxide, and a natural mineral with the acid leaching solution, and simultaneously adding the mixture dropwise to water with an alkaline solution, stirring and adjusting the pH, heating and stirring for a period of time, and then aging to induce crystallization of metal ions in the acid leaching solution, and performing solid-liquid separation to obtain a lithium-rich solution and a second solid; (4) The second solid is washed with water and dried to obtain a layered double hydroxide.

2. The method according to claim 1, characterized in that In step (1), the lithium-containing silicate mineral is selected from any one or more of spodumene, petalite, eucryptite, lepidolite, iron lithium mica, hectorite, lithium kaolinite, lithium illite, hectorite, lithium chlorite and lithium zeolite.

3. The method according to claim 1, characterized in that In step (1), the mass ratio of the lithium-containing silicate mineral to the first metal inorganic salt is 1:(0.1-10).

4. The method according to claim 1, wherein In step (1), the ball milling speed is 300-900 rpm and the time is 1-10 h.

5. The method according to claim 1, wherein In step (2), the acid solution is selected from any one or more of hydrochloric acid, nitric acid, phosphoric acid, formic acid, acetic acid and oxalic acid; and the concentration of the acid solution is at least 0.01 mol / L.

6. The method according to claim 1, characterized in that In step (2), the high temperature pressurization conditions are a temperature of 60-240°C, a pressure of 0.2-2.0 MPa, a filling rate of the container of 10-80%, and a time of 2-48 hours.

7. The method according to claim 1, characterized in that In step (2), the drying temperature of the first solid is 60-120°C.

8. The method according to claim 1, characterized in that In step (3), the second metal inorganic salt is selected from any one or more of magnesium nitrate, aluminum nitrate, calcium nitrate, magnesium chloride, aluminum chloride, calcium chloride, magnesium sulfate and aluminum sulfate; or / and, the alkaline solution, the alkali being selected from metal hydroxides; Or / and, the natural mineral is at least one selected from dolomite, limestone, magnesite, and calcite; Or / and, the pH is 7-13.

9. The method according to claim 8, characterized in that In step (3), the alkali solution is selected from any one or more of potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, iron hydroxide, nickel hydroxide, cobalt hydroxide and barium hydroxide.

10. The method according to claim 1, characterized in that In step (3), the temperature is raised and stirred to 60-150°C for 2-3 hours; Or / and, the aging temperature is 75-120° C. and the time is 2-18 hours.

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