A method for simultaneously extracting lithium and silicon from lithium-containing minerals

Abstract

The present invention discloses a method for simultaneously extracting lithium and silicon from lithium-containing minerals. The method comprises: subjecting the lithium-containing mineral to a reduction reaction under the action of a metal reducing agent to produce a reduction product; ball-milling the reduction product under an inert gas atmosphere; and leaching the product in water to obtain a lithium-rich water solution and a first solid; subjecting the first solid to a first dilute acid leaching to obtain a lithium-rich acid solution and a second solid; obtaining a silicon nanomaterial from the second solid; and adding the lithium-rich acid solution or a mixture of the lithium-rich acid solution and a natural mineral dropwise to water simultaneously with an alkaline solution, stirring and controlling the pH, heating and stirring for a period of time to perform dynamic crystallization, followed by static crystallization, and solid-liquid separation to obtain a lithium-rich supernatant and a third solid; and obtaining a layered polymetallic hydroxide from the third solid. The present invention couples the lithium extraction process with the silicon nanomaterial preparation process, fully utilizing elements such as lithium and silicon in the mineral, achieving comprehensive element utilization, avoiding resource waste, and significantly improving economic efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium extraction, and in particular to a method for simultaneously extracting lithium and silicon from lithium-containing minerals. Background Art

[0002] Lithium, the lightest known metallic element, has been widely used in energy storage / power batteries, metal materials, military equipment, and other fields due to its attractive electrochemical properties and other unique attributes. Lithium-ion batteries are high-energy storage media, and their rapid development has driven the booming business of lithium mining and lithium carbonate companies. The global wave of electrification has created unprecedented opportunities for lithium, making the lithium industry a booming sector that countries are vying to develop.

[0003] Lithium ore resources primarily include pegmatite, granite, and clay types. Currently, the industrial development of lithium ore has become increasingly mature. Lithium extraction requires the destruction of the mineral structure. The main processes include limestone roasting, sulfuric acid roasting, soda autoclave, and chloride roasting.

[0004] The limestone method involves mixing limestone and lepidolite in a specific mass ratio (generally 1:3), grinding the mixture to a desired fineness using a ball mill, and then calcining the mixture at 800-900°C before leaching to produce a lithium-containing solution. This method is highly practical and suitable for almost all lithium minerals, but it also results in high evaporation energy consumption, a low lithium recovery rate (around 67%), and a large amount of slag (42 tons of slag per ton of product).

[0005] For example, Yan et al. calcined a mixture of lepidolite, calcium chloride, and sodium chloride at 880°C and subsequently leached the chlorinated calcined sample with water at 60°C (Yan et al., Trans. Nonferrous Met. Soc. China, 2012, 22(7):1753-1759). Although this method does not consume expensive reagents, it involves the use of high concentrations of chloride and requires highly corrosion-resistant equipment.

[0006] Chinese patent application CN115466853A discloses a method and apparatus for extracting lithium from lepidolite using a vertical grinding process. This method primarily utilizes sulfuric acid leaching to extract lithium, mixing lithium ore with 50% to 80% concentrated sulfuric acid and roasting it at 150 to 180°C. This method has significant drawbacks, including high energy and acid consumption, and subsequent neutralization and slurry preparation, which consumes a significant amount of soda ash and is therefore costly.

[0007] In summary, industrial lithium extraction processes involve either high-temperature roasting followed by leaching and crystallization, or the use of concentrated sulfuric acid, sulfates, limestone, chlorides, and other reagents. These processes are characterized by high energy consumption, environmental unfriendliness, and strong corrosion to equipment, placing high demands on equipment. Furthermore, in industrial lithium extraction processes, the tailings after lithium extraction are often discarded as "solid waste," but in reality, the slag still contains a large amount of silicon, magnesium, and aluminum, which are derived from the structure of the lithium ore itself. Silicon is considered the most promising negative electrode material for lithium-ion batteries, with a theoretical specific capacity far superior to commercial graphite negative electrode materials (4200 vs. 372 mAh / g). If the lithium, silicon, magnesium, and aluminum elements in lithium ore can be comprehensively extracted, the economic benefits will be greatly improved. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for simultaneously extracting lithium and silicon from lithium-containing minerals, which solves the problems of high energy consumption, large consumption of acid and alkali reagents, high equipment requirements 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 minerals.

[0009] To achieve the above-mentioned object, the present invention provides a method for simultaneously extracting lithium and silicon from lithium-containing minerals, the method comprising: subjecting the lithium- and silicon-containing minerals to a reduction reaction under the action of a metal reducing agent, reducing the silicon-containing compound to elemental silicon, and simultaneously converting the lithium into a form that is easily leached to obtain a reduction product, and subjecting the reduction product to lithium ion leaching treatment to obtain a lithium-rich leachate and a solid; wherein the lithium ion leaching treatment comprises: subjecting the reduction product to atmosphere ball milling under an inert gas atmosphere, leaching lithium ions with water, and separating the solid and liquid to obtain a lithium-rich water leachate and a first solid; or subjecting the reduction product to a first dilute acid leaching, and separating the solid and liquid to obtain a lithium-rich acid leachate and a first solid A; The first solid is subjected to a first dilute acid leaching to leach lithium ions, and solid-liquid separation is performed to obtain a lithium-rich acid leaching solution and a second solid; the second solid is subjected to a second dilute acid washing and water washing to obtain a silicon nanomaterial; or the first solid A is subjected to a second dilute acid washing and water washing to obtain a silicon / silicon dioxide nanomaterial; the lithium-rich acid leaching solution or the lithium-rich acid leaching solution and a natural mineral are mixed and then added dropwise to water simultaneously with an alkaline solution, stirred and the pH is adjusted, and the temperature is increased and stirred for a period of time to perform dynamic crystallization, followed by static crystallization to crystallize the layered polymetallic hydroxide, and solid-liquid separation is performed to obtain a lithium-rich supernatant and a third solid; the third solid is washed with water and dried to obtain layered polymetallic hydroxide crystals.

[0010] The method of the present invention subjects the lithium-containing mineral to a reduction reaction under the action of a reducing agent. During the reduction reaction, the reducing agent strongly deprives the mineral structure of oxygen and destroys the mineral structure, reducing silicon dioxide to silicon and simultaneously converting lithium into a form that is easily leached, effectively avoiding the use of highly concentrated acid and alkali, high temperature, and high pressure roasting to destroy the mineral structure. During the lithium extraction process after metal thermal reduction, the reduction product is ball-milled to break up and depolymerize the reduction product to expose lithium-containing particles. Subsequently, nearly half the mass of lithium can be extracted by simply leaching the reduction product. Because the metal elements contained in the lithium-containing mineral are converted into insoluble forms during the reduction process, for example, magnesium is converted into magnesium oxide and magnesium silicide, aluminum is converted into aluminum and aluminum oxide, and iron is converted into iron, iron oxide, and iron silicide. All of these substances are insoluble in water, while lithium and lithium oxide are both readily soluble in water. Therefore, lithium can be dissolved during water leaching, while magnesium and aluminum are difficult to dissolve, resulting in an extremely low magnesium-to-lithium (mass) ratio in the water leaching solution, which is beneficial for the separation of magnesium and lithium. After water leaching, acid leaching is used to leach out the vast majority of the remaining lithium. Although the acid leaching solution contains large amounts of magnesium, aluminum, and lithium ions, the magnesium and aluminum will enter the layered polymetallic hydroxide crystals during the preparation of the layered polymetallic hydroxide crystals in the next step. Lithium, due to its valence mismatch with magnesium, does not enter the layered polymetallic hydroxide crystals. Instead, it enters the supernatant of the layered polymetallic hydroxide crystals in the form of ions. At this point, the supernatant contains extremely low magnesium and almost no lithium loss, that is, the supernatant has an extremely low magnesium-to-lithium ratio, which is also very conducive to the separation of magnesium and lithium.

[0011] Preferably, the reduction reaction is carried out in a heating container filled with inert gas; the temperature of the reduction reaction is 600-1000° C., and the holding time is 1-20 hours; the inert gas is at least one of helium and argon.

[0012] More preferably, the temperature of the reduction reaction is 600-900° C., and the holding time is 2-6 hours; and the inert gas is argon.

[0013] More preferably, the temperature of the reduction reaction is 650-750°C.

[0014] Preferably, the mass ratio of the lithium-containing mineral to the reducing agent is (1-10): (1-8); and / or, the mass concentration of the first dilute acid is 1-20%; the mass concentration of the second dilute acid is 1-20%; and / or, the pH is 6.5-13. pH affects the crystallization of layered polymetallic hydroxides, including grain size, crystal morphology, etc. If the pH is too low, Mg 2+ It is difficult to precipitate, so the pH is controlled at 6.5-13.

[0015] Preferably, the lithium-containing mineral is selected from any one or more of spodumene, petalite, eucryptite, lepidolite, iron lithium mica, hectorite, lithium kaolinite, lithium illite, hectorite, lithium chlorite, lithium zeolite and jaddarite.

[0016] Preferably, the metal reducing agent is metal powder; the metal powder is selected from any one or more of magnesium, aluminum, zinc, sodium, potassium and calcium; and / or the mass ratio of the lithium-containing mineral to the reducing agent is (10-1):(1-5).

[0017] More preferably, the mass ratio of the lithium-containing mineral to the reducing agent is (3-1):(1-2).

[0018] Preferably, the lithium-containing mineral and the reducing agent are mixed evenly before the reduction reaction; or, the lithium-containing mineral, the reducing agent and the metal inorganic salt are mixed evenly before the reduction reaction; and / or, the metal inorganic salt is selected from any one or more of sodium chloride, potassium chloride, magnesium chloride, lithium chloride and calcium chloride; and / or, the mass ratio of the lithium-containing mineral to the metal inorganic salt is 1:(1 to 5).

[0019] Preferably, the rotation speed of the atmosphere ball mill is 200-800 rpm, the time is 0.1-10 h, and the atmosphere introduced into the ball mill is selected from any one or more of helium, nitrogen and argon.

[0020] Preferably, the number of water immersion is 1 to 10 times, and the form of water immersion is any one or more of magnetic stirring water immersion, homogenizer water immersion, and ultrasonic water immersion.

[0021] Preferably, the first dilute acid and the second dilute acid are each independently selected from any one or more of hydrochloric acid, sulfuric acid, hydrofluoric acid, nitric acid and phosphoric acid; and / or the mass concentration of the dilute acid is 1 to 20%; and / or the washing time of the pickling is 0.1 to 10 hours; and / or the alkaline solution is prepared using an alkali and / or a salt; the alkali used in the preparation includes any one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide and zinc hydroxide; the salt used in the preparation includes any one or more of sodium carbonate, potassium carbonate and calcium carbonate.

[0022] Preferably, the natural mineral is selected from any one or more of dolomite, magnesite and limestone.

[0023] Preferably, the temperature of the dynamic crystallization is 60-120° C., and the time is 1-10 h; the temperature of the static crystallization is 60-180° C., and the time is 2-48 h.

[0024] More preferably, the temperature of the dynamic crystallization is 70-100° C., and the time is 2-4 hours; the temperature of the static crystallization is 75-140° C., and the time is 9-18 hours.

[0025] The method of the present invention for simultaneously extracting lithium and silicon from lithium-containing minerals solves the problems of high energy consumption, large consumption of acid and alkali reagents, high equipment requirements and low resource utilization efficiency in existing lithium ore extraction processes, and has the following advantages:

[0026] (1) The present invention proposes for the first time to extract lithium by metal thermal reduction of lithium-containing minerals, water leaching, dilute acid leaching, or metal thermal reduction of lithium-containing minerals and dilute acid leaching, coupling the lithium extraction process with the process of preparing silicon nanomaterials. In the process of the metal reducing agent strongly depriving the mineral structure of oxygen and destroying the mineral structure, the lithium element in the mineral lattice or interlayer and the silicon element in the lattice are simultaneously converted into lithium element and elemental silicon that are easy to leach. After metal thermal reduction, the lithium can be leached by water leaching, acid leaching or direct acid leaching of the product. Then, magnesium and lithium are separated by preparing layered polymetallic hydroxide crystals. The magnesium-lithium ratio of the lithium-rich supernatant obtained by preparing layered polymetallic hydroxide crystals is greatly reduced (compared to the lithium-rich acid leaching solution), which is conducive to the subsequent extraction of lithium. As for the treatment of elemental silicon, silicon nanomaterials can be obtained by adding dilute acid pickling, water washing, and drying, which can be used in the field of lithium-ion batteries. The prepared layered polymetallic hydroxide crystals can be used for adsorption, catalysis, refractory materials, etc.

[0027] (2) The lithium-containing minerals used in the present invention have abundant reserves and low costs. The method for extracting lithium and silicon is efficient, simple in process, and low in energy consumption. It fully utilizes the lithium, silicon and other elements in the minerals, realizes the comprehensive utilization of elements, avoids the waste of resources, and greatly improves economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a process flow chart of the method for simultaneously extracting lithium and silicon from lithium-containing minerals.

[0029] Figure 2 The lithium extraction efficiency and the magnesium-lithium ratio of the lithium-rich liquid in each step of Example 1 of the present invention are shown; the columns correspond to the lithium extraction rate on the left axis; and the dotted line corresponds to the magnesium-lithium ratio on the right axis.

[0030] Figure 3 This is the X-ray diffraction pattern of nano-silicon prepared in Example 1 of the present invention.

[0031] Figure 4 This is a scanning electron microscope image of nano-silicon prepared in Example 1 of the present invention.

[0032] Figure 5 The nano-silicon prepared in Example 1 of the present invention is used as the negative electrode material of lithium-ion batteries and assembled into button batteries to measure the battery cycle performance.

[0033] Figure 6 This is the X-ray diffraction pattern of the magnesium-aluminum layered polymetallic hydroxide prepared in Example 1 of the present invention.

[0034] Figure 7 This is a scanning electron microscope image of the magnesium-aluminum layered polymetallic hydroxide prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0036] Note: If the specific conditions are not specified in the examples, the experiments were carried out according to conventional conditions or those recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all commercially available conventional products.

[0037] Example 1

[0038] A method for simultaneously extracting lithium and silicon from lithium-containing minerals comprises the following steps:

[0039] (1) The particle size of lepidolite is large, and the flakes are difficult to fully expose, and the metal thermal reduction reaction will be insufficient. Therefore, it is necessary to crush the lepidolite in advance to reduce the particle size. Specifically, the lepidolite is placed in a planetary ball mill at a speed of 600 rpm for 3 hours to obtain ball-milled fine-grained lepidolite;

[0040] (2) 10 g of ball-milled fine-grained lepidolite, 8 g of magnesium powder, and 50 g of sodium chloride were mixed and placed in a stainless steel reactor. The reactor was placed in a tube furnace and heated to 750°C under an argon atmosphere and kept at this temperature for 5 h. The reduced product was then added to a ball mill vented with nitrogen, and the ball mill was placed in a planetary ball mill and ball milled at 400 rpm for 1 h.

[0041] (3) 13.60 g of the ball-milled reduction product was placed in a beaker for water immersion, 200 mL of deionized water was added, and after magnetic stirring for 1 h, solid-liquid separation was performed to obtain a first solid and a lithium-rich water immersion solution. The water immersion process of the first solid was repeated five times, and solid-liquid separation was performed to obtain the first solid and five lithium-rich water immersion solutions;

[0042] (4) placing the first solid in 150 mL of a 3.6 wt.% hydrochloric acid solution and stirring for acid leaching for 1 hour, followed by solid-liquid separation to obtain a second solid and a lithium-rich acid leaching solution;

[0043] (5) washing the second solid with 1% by volume HF, washing with water, and drying to obtain a silicon nanomaterial;

[0044] (6) Treatment process of lithium-rich acid leaching solution: At room temperature, the lithium-rich acid leaching solution and alkaline solution are added drop by drop into the same beaker pre-filled with 135 mL of deionized water through a pH automatic liquid adding machine, and vigorous mechanical stirring and constant pH (pH = 9 ± 0.2) are maintained. After the addition is completed, the temperature is raised to 75 ° C, and mechanical stirring is maintained for dynamic crystallization for 3 hours, and then static crystallization is carried out at 90 ° C in an oven for 18 hours; after the crystallization is completed, the solid-liquid mixture in the beaker is centrifuged, and the third solid is washed with water several times and centrifuged until the pH of the supernatant is close to neutral, and dried at 80 ° C to obtain magnesium-aluminum layered double hydroxide, and the separated liquid is a lithium-rich supernatant.

[0045] The lithium-rich water extract in step (3) and the lithium-rich supernatant in step (6) are both used for subsequent lithium extraction.

[0046] The alkali solution was prepared by adding 3.20 g of sodium hydroxide and 1.70 g of sodium carbonate into a beaker and dissolving them in 200 mL of water.

[0047] like Figure 2 As shown, the lithium extraction efficiency and magnesium-lithium ratio of the lithium-rich liquid in each step of Example 1 of the present invention are shown. After metallothermic reduction and ball milling, lithium can be leached out in five water leachings of the reduced product. The content of leached lithium gradually decreases with the increase in the number of leachings. At this time, the lithium extraction rate of the five water leachings (the lithium content of each step divided by the total lithium content of the added lithium-containing minerals) can reach nearly 50%. Due to the low water solubility of magnesium oxide and magnesium, the magnesium-lithium ratio of the water leaching solution is extremely low (all less than 1), which is conducive to further extraction of lithium. The subsequent acid leaching leaches out most of the remaining lithium. Although the magnesium-lithium ratio of the acid leaching solution is relatively high, the subsequent preparation of layered polymetallic hydroxides removes magnesium and aluminum, greatly reducing the magnesium-lithium ratio of the solution. The total lithium extraction rate can reach 93.4%.

[0048] like Figure 3 , which is the X-ray diffraction pattern of the nano-silicon prepared in Example 1 of the present invention. It can be seen from the figure that the obtained silicon material has a single phase and a small grain size.

[0049] like Figure 4 , which is a scanning electron microscope image of the nano-silicon prepared in Example 1 of the present invention. It can be seen from the figure that although the obtained silicon material is agglomerated, the particles are fine.

[0050] like Figure 5 As shown in the figure, the nano-silicon prepared in Example 1 of the present invention is used as a negative electrode material for lithium-ion batteries and assembled into a button battery. As can be seen from the figure, the material has good cycle performance as a lithium battery negative electrode. -1 After 500 cycles at a current density of 850 mAh g -1 Specific capacity.

[0051] like Figure 6 , which is the X-ray diffraction pattern of the magnesium-aluminum layered double hydroxide prepared in Example 1 of the present invention. It can be seen from the figure that the diffraction characteristics of the obtained magnesium-aluminum layered double hydroxide are obvious and the phase is single.

[0052] like Figure 7 , which is a scanning electron microscope image of the magnesium-aluminum layered double hydroxide prepared in Example 1 of the present invention. It can be seen from the figure that the obtained magnesium-aluminum layered double hydroxide has a flaky morphology, and the diameter of most flakes is less than 100 nm.

[0053] Example 2

[0054] A method for simultaneously extracting lithium and silicon from lithium-containing minerals comprises the following steps:

[0055] (1) The particle size of spodumene is large, and the structure is difficult to fully expose, and the metal thermal reduction reaction will be insufficient. Therefore, it is necessary to crush the spodumene in advance to reduce the particle size. Specifically, the spodumene is placed in a planetary ball mill at a speed of 800 rpm for 2 hours to obtain fine-grained spodumene;

[0056] (2) 10 g of fine-grained spodumene (milled) and 5 g of magnesium powder were mixed and placed in a stainless steel reactor. The reactor was placed in a tube furnace and heated to 650°C under an argon atmosphere for 5 h. The reduced product was then added to a ball mill vented with nitrogen. The ball mill was placed in a planetary ball mill and milled at 500 rpm for 1 h.

[0057] (3) 7.5 g of the ball-milled reduction product was placed in a beaker for water immersion, 200 mL of deionized water was added, and after ultrasonic water immersion for 1 h, solid-liquid separation was performed to obtain a first solid and a lithium-rich water immersion solution. The water immersion process of the first solid was repeated seven times, and solid-liquid separation was performed to obtain the first solid and seven lithium-rich water immersion solutions;

[0058] (4) placing the first solid in 200 mL of a 10 wt.% nitric acid solution and stirring for acid leaching for 10 h, followed by solid-liquid separation to obtain a second solid and a lithium-rich acid leaching solution;

[0059] (5) washing the second solid with 1% by volume HF, washing with water, and drying to obtain a silicon nanomaterial;

[0060] (6) Treatment process of lithium-rich acid leaching solution: 2.12g of dolomite is added to the lithium-rich acid leaching solution to supplement the magnesium source and dissolve it. At room temperature, the lithium-rich acid leaching solution and the alkaline solution are added drop by drop into the same beaker pre-filled with 135mL of deionized water through a pH automatic liquid adding machine, and vigorous mechanical stirring and constant pH (pH = 9 ± 0.2) are maintained. After the addition is completed, the temperature is raised to 80°C, and mechanical stirring is maintained for dynamic crystallization for 2 hours, followed by static crystallization at 120°C in an oven for 12 hours; after the crystallization is completed, the solid-liquid mixture in the beaker is centrifuged, and the third solid is washed with water several times and centrifuged until the pH of the supernatant is close to neutral, and then dried at 80°C to obtain magnesium-aluminum layered double metal hydroxide, and the total lithium extraction rate is 89.3%.

[0061] The alkali solution was prepared by adding 4.60 g of sodium hydroxide and 2.44 g of sodium carbonate into a beaker and dissolving them in 200 mL of water.

[0062] Example 3

[0063] A method for simultaneously extracting lithium and silicon from lithium-containing minerals comprises the following steps:

[0064] (1) 10 g of hectorite, 6 g of magnesium powder, and 30 g of sodium chloride were mixed and placed in a stainless steel reactor. The reactor was placed in a tube furnace and heated to 700°C under an argon atmosphere and kept at this temperature for 5 h. The reduced product was then added to a ball mill vented with nitrogen, which was then placed in a planetary ball mill and ball milled at 350 rpm for 1 h.

[0065] (2) 9.20 g of the ball-milled reduction product was placed in a beaker for water immersion, 200 mL of deionized water was added, and after magnetic stirring for 1 h, solid-liquid separation was performed to obtain a first solid and a lithium-rich water immersion solution. The water immersion process of the first solid was repeated three times, and solid-liquid separation was performed to obtain a first solid and three lithium-rich water immersion solutions;

[0066] (3) placing the first solid in 200 mL of a 6 wt.% sulfuric acid solution and stirring for acid leaching for 1 hour, followed by solid-liquid separation to obtain a second solid and a lithium-rich acid leaching solution;

[0067] (4) washing the second solid with 1% by volume HF, washing with water, and drying to obtain a silicon nanomaterial;

[0068] (5) Treatment process of lithium-rich acid leaching solution: 1.20g of calcite is added to the lithium-rich acid leaching solution to supplement the calcium source and dissolve it. At room temperature, the above lithium-rich acid leaching solution and alkaline solution are added drop by drop into the same beaker pre-filled with 160mL of deionized water through a pH automatic liquid adding machine, and vigorous mechanical stirring and constant pH (pH = 9 ± 0.2) are maintained. After the addition is completed, the temperature is raised to 95°C, and mechanical stirring is maintained for dynamic crystallization for 2h, followed by static crystallization at 140°C in an oven for 15h; after the crystallization is completed, the solid-liquid mixture in the beaker is centrifuged, and the third solid is washed with water several times and centrifuged until the pH of the supernatant is close to neutral, and dried at 80°C to obtain calcium aluminum layered double hydroxide, and the total lithium extraction rate is 91.2%.

[0069] The alkali solution was prepared by adding 3.80 g of sodium hydroxide and 2.02 g of sodium carbonate into a beaker and dissolving them in 200 mL of water.

[0070] Example 4

[0071] A method for simultaneously extracting lithium and silicon from lithium-containing minerals comprises the following steps:

[0072] (1) 10 g of hectorite, 7 g of magnesium powder, and 50 g of sodium chloride were mixed and placed in a stainless steel reactor. The reactor was placed in a tube furnace and heated to 700°C under an argon atmosphere and kept at this temperature for 5 h. The reduced product was then added to a ball mill vented with nitrogen. The ball mill was placed in a planetary ball mill and ball milled at 350 rpm for 1 h.

[0073] (2) 13.40 g of the ball-milled reduction product was placed in a beaker for water immersion, 200 mL of deionized water was added, and after magnetic stirring for 1 h, solid-liquid separation was performed to obtain a first solid and a lithium-rich water immersion solution. The water immersion process of the first solid was repeated three times, and solid-liquid separation was performed to obtain a solid and three lithium-rich water immersion solutions;

[0074] (3) placing the first solid in 200 mL of a 3.6 wt.% hydrochloric acid solution and stirring for acid leaching for 1 hour, followed by solid-liquid separation to obtain a second solid and a lithium-rich acid leaching solution;

[0075] (4) washing the second solid with 1% by volume HF, washing with water, and drying to obtain a silicon nanomaterial;

[0076] (5) Treatment process of lithium-rich acid leaching solution: 1.67g of dolomite is added to the lithium-rich acid leaching solution to supplement the magnesium source and dissolve it. At room temperature, the above lithium-rich acid leaching solution and alkaline solution are added drop by drop into the same beaker pre-filled with 160mL of deionized water through a pH automatic liquid adding machine, and vigorous mechanical stirring and constant pH (pH = 9 ± 0.2) are maintained. After the addition is completed, the temperature is raised to 95°C, and mechanical stirring is maintained for dynamic crystallization for 2h, followed by static crystallization at 140°C in an oven for 15h; after the crystallization is completed, the solid-liquid mixture in the beaker is centrifuged, and the solid is washed with water several times and centrifuged until the pH of the supernatant is close to neutral, and then dried at 80°C to obtain zinc-magnesium-aluminum layered trimetallic hydroxide, with a total lithium extraction rate of 92.5%.

[0077] The alkali solution was prepared by adding 1.60 g of sodium hydroxide, 3.98 g of zinc hydroxide and 4.24 g of sodium carbonate into a beaker, and then adding 200 mL of water.

[0078] Example 5

[0079] A method for simultaneously extracting lithium and silicon from lithium-containing minerals comprises the following steps:

[0080] (1) 10 g of lithium chlorite, 5 g of magnesium powder, and 20 g of sodium chloride were mixed and placed in a stainless steel reactor. The reactor was placed in a tube furnace and heated to 750°C under an argon atmosphere and kept at this temperature for 5 h. The reduced product was then added to a ball mill vented with nitrogen, which was then placed in a planetary ball mill and ball milled at 350 rpm for 1 h.

[0081] (2) 7 g of the ball-milled reduction product was placed in a beaker for dilute acid leaching, 200 mL of 3.6 wt.% HCl was added, and after magnetic stirring for 1 h, solid-liquid separation was performed to obtain a first solid and a lithium-rich acid leaching solution;

[0082] (3) subjecting the first solid to a second dilute acid wash and a water wash to obtain a silicon / silicon dioxide nanomaterial;

[0083] (4) Lithium-rich acid leaching process: 1.24g dolomite is added to the lithium-rich acid leaching solution to supplement the magnesium source and dissolve it. At room temperature, the above acid leaching solution and alkali solution are added drop by drop into the same beaker pre-filled with 135mL deionized water through a pH automatic liquid adding machine, and vigorous mechanical stirring and constant pH (pH = 9 ± 0.2) are maintained. After the addition is completed, the temperature is raised to 80°C, and mechanical stirring is maintained for dynamic crystallization for 3 hours, followed by static crystallization at 120°C in an oven for 18 hours; after the crystallization is completed, the solid-liquid mixture in the beaker is centrifuged, and the third solid is washed with water several times and centrifuged until the pH of the supernatant is close to neutral, and then dried at 80°C to obtain calcium magnesium aluminum layered trimetallic hydroxide, and the total lithium extraction rate is 88.2%.

[0084] The above alkali solution was prepared by adding 2.12 g of sodium hydroxide and 1.27 g of sodium carbonate into a beaker and then adding 200 mL of water.

[0085] Comparative Example 1

[0086] A method for simultaneously extracting lithium and silicon from lithium-containing minerals comprises the following steps:

[0087] The amount of magnesium powder in step (2) of Example 1 was reduced from 8 g to 0.5 g, and the rest was the same as in Example 1.

[0088] In Comparative Example 1, 0.5g of magnesium powder failed to completely reduce 10g of lepidolite. The reaction did not sufficiently destroy the lepidolite structure, preventing the leaching of lithium from its octahedral structure. This significantly reduced the lithium extraction rate, resulting in a total lithium extraction rate of only 27.2%. The XRD pattern of the solid product obtained from the acid leaching reduction contained characteristic diffraction peaks for lepidolite, quartz, and silicon, indicating inadequate reduction and significantly reducing the silicon yield. Therefore, the amount of magnesium powder needed to be adjusted to an appropriate range.

[0089] Comparative Example 2

[0090] A method for simultaneously extracting lithium and silicon from lithium-containing minerals comprises the following steps:

[0091] The constant pH in step (6) of Example 2 was changed from 9±0.2 to 5±0.2, and the rest was the same as Example 2.

[0092] The total lithium extraction rate of the method in Comparative Example 2 is 65.8%. - The concentration is not enough to make Mg 2+ Complete precipitation, so when preparing magnesium aluminum layered double hydroxide, Mg 2+ With Al 3+ The coprecipitation is not sufficient, so there is still a lot of Mg in the acid leaching solution. 2+ The presence of Mg / Li makes its Mg / Li ratio 72. Too high a Mg / Li ratio will affect the further extraction of lithium. Therefore, the pH needs to be adjusted to an appropriate range.

[0093] Comparative Example 3

[0094] A method for simultaneously extracting lithium and silicon from lithium-containing minerals comprises the following steps:

[0095] The mass concentration of hydrochloric acid in step (2) in Example 5 was changed from 3.6 wt.% to 36 wt.%, and the rest was the same as in Example 5.

[0096] The total lithium extraction rate of the method in Comparative Example 3 is 89.1%. Although the total lithium extraction rate is high, due to the excessively high acid concentration, hydrochloric acid reacts violently with the reduction product (Mg2Si in the reduction product) during acid leaching to generate silane gas, producing an explosive sound, releasing a large amount of heat and emitting a large amount of bubbles, which makes the resulting nano-silicon agglomeration phenomenon more serious. In addition, due to the high molar amount of hydrochloric acid used, a large amount of alkali needs to be added to neutralize the acid to reach the target pH when preparing the magnesium-aluminum layered double hydroxide. This consumes a large amount of reagents and water, resulting in high costs. The salinity of the wastewater after neutralization is high, which is not environmentally friendly. Therefore, it is necessary to select an appropriate acid concentration.

[0097] 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 simultaneously extracting lithium and silicon from lithium-containing minerals, characterized in that: The method includes: A lithium- and silicon-containing mineral is subjected to a reduction reaction under the action of a metal reducing agent, wherein the reduction reaction temperature is 600-1000° C., the silicon-containing compound is reduced to silicon elemental substance, and the lithium is converted into a form that is easily leached to obtain a reduction product, and the reduction product is subjected to lithium ion leaching treatment to obtain a lithium-rich leachate and a solid; the lithium-containing mineral is selected from any one or two or more of spodumene, petalite, eucryptite, lepidolite, ferroleum mica, hectorite, lithium kaolinite, lithium illite, hectorite, lithium chlorite and lithium zeolite; and the metal reducing agent is selected from any one or two or more of magnesium, zinc and calcium; The lithium ion leaching treatment comprises: subjecting the reduction product to atmosphere ball milling under an inert gas atmosphere, leaching the lithium ions in water, and separating the solid and liquid to obtain a lithium-rich water leaching solution and a first solid; or subjecting the reduction product to a first dilute acid leaching, and separating the solid and liquid to obtain a lithium-rich acid leaching solution and a first solid A, wherein the first dilute acid is independently selected from any one or more of hydrochloric acid, sulfuric acid, hydrofluoric acid, nitric acid, and phosphoric acid; subjecting the first solid to a first dilute acid leaching to leach lithium ions, and separating the solid and the liquid to obtain a lithium-rich acid leaching solution and a second solid, wherein the first dilute acid is independently selected from any one or more of hydrochloric acid, sulfuric acid, hydrofluoric acid, nitric acid, and phosphoric acid; The second solid is subjected to a second dilute acid washing and water washing treatment to obtain a silicon nanomaterial, wherein the second dilute acid is selected from hydrofluoric acid; or the first solid A is subjected to a second dilute acid washing and water washing treatment to obtain a silicon / silicon dioxide nanomaterial, wherein the second dilute acid is selected from any one or more of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; The lithium-rich acid leachate or a mixture of the lithium-rich acid leachate and a natural mineral is added dropwise to water simultaneously with an alkaline solution, stirred, and the pH is adjusted to 6.5 to 13. The temperature is raised and stirred for a period of time to perform dynamic crystallization, followed by static crystallization to crystallize the layered polymetallic hydroxide, and solid-liquid separation to obtain a lithium-rich supernatant and a third solid; wherein the natural mineral is selected from any one or more of dolomite, magnesite, and limestone; The third solid is washed with water and dried to obtain layered polymetallic hydroxide crystals.

2. The method for simultaneously extracting lithium and silicon from lithium-containing minerals according to claim 1, characterized in that: The reduction reaction is carried out in a heating container filled with an inert gas; the reduction reaction has a holding time of 1 to 20 hours; and the inert gas is at least one of helium and argon.

3. The method for simultaneously extracting lithium and silicon from lithium-containing minerals according to claim 1, characterized in that: The mass ratio of the lithium-containing mineral to the reducing agent is (1-10):(1-8); And / or, the mass concentration of the first dilute acid is 1-20%; the mass concentration of the second dilute acid is 1-20%.

4. The method for simultaneously extracting lithium and silicon from lithium-containing minerals according to claim 1, characterized in that: The metal reducing agent is metal powder.

5. The method for simultaneously extracting lithium and silicon from lithium-containing minerals according to claim 1, characterized in that: Before the reduction reaction, the lithium-containing mineral and the reducing agent are mixed evenly; or, before the reduction reaction, the lithium-containing mineral, the reducing agent and the metal inorganic salt are mixed evenly; And / or, the metal inorganic salt is selected from any one or more of sodium chloride, potassium chloride, magnesium chloride, lithium chloride and calcium chloride; And / or, the mass ratio of the lithium-containing mineral to the metal inorganic salt is 1:(1-5).

6. The method for simultaneously extracting lithium and silicon from lithium-containing minerals according to claim 1, characterized in that: The rotation speed of the atmosphere ball mill is 200-800 rpm, the time is 0.1-10 h, and the atmosphere introduced into the ball mill is selected from any one or more of helium, nitrogen, and argon.

7. The method for simultaneously extracting lithium and silicon from lithium-containing minerals according to claim 1, characterized in that: The washing time of pickling is 0.1~10h; And / or, the alkaline solution is prepared using an alkali and / or a salt; the alkali used in the preparation includes any one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide and zinc hydroxide; the salt used in the preparation includes any one or more of sodium carbonate, potassium carbonate and calcium carbonate.

8. The method for simultaneously extracting lithium and silicon from lithium-containing minerals according to claim 1, characterized in that: The temperature of the dynamic crystallization is 60-120° C., and the time is 1-10 hours; the temperature of the static crystallization is 60-180° C., and the time is 2-48 hours.

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