Method for simultaneously extracting lithium and silicon from lithium-containing minerals

Abstract

The invention discloses a method for simultaneously extracting lithium and silicon from a lithium-containing mineral, which comprises the following steps: carrying out reduction reaction on the lithium-containing mineral under the action of a metal reducing agent to prepare a reduction product, and carrying out atmosphere ball milling and water leaching on the reduction product in an inert gas atmosphere to obtain a lithium-rich water leaching solution and a first solid; carrying out first dilute acid leaching on the first solid to obtain a lithium-rich pickle liquor and a second solid; obtaining a silicon nanomaterial from the second solid; the lithium-rich pickle liquor or a mixture of the lithium-rich pickle liquor and natural minerals and an alkali solution are dropwise added into water at the same time, stirring is conducted, pH is regulated and controlled, heating stirring is conducted for a period of time for dynamic crystallization, then static crystallization is conducted, and solid-liquid separation is conducted to obtain lithium-rich supernate and a third solid; a layered multi-metal hydroxide is obtained from the third solid. According to the method, a lithium extraction process and a silicon nano material preparation process are coupled, elements such as lithium and silicon in minerals are fully utilized, comprehensive utilization of the elements is realized, waste of resources is avoided, and economic benefits are greatly improved.

Description

Technical Field

[0001] The 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 is the lightest known metal element. Due to its attractive electrochemical characteristics and other unique properties, it has been widely used in energy storage / power batteries, metal materials, military equipment and other fields. Lithium-ion batteries are high-energy storage media. Due to their rapid development, they have led to the booming business of lithium mines, lithium carbonate and other companies. Today, the global electrification wave has created an unprecedented huge space for lithium, and the lithium industry has become an emerging sunrise industry that countries are competing to develop.

[0003] Among lithium ore resources, there are mainly pegmatite type, granite type and clay type lithium ore. At present, the industrial development of lithium ore has become increasingly mature. The extraction of lithium is inseparable from the destruction of mineral structure. The main processes include limestone roasting, sulfuric acid roasting, soda pressure cooking, and chloride roasting.

[0004] The limestone method is to mix limestone and lithium mica in a certain mass ratio (generally 1:3), grind them to a certain fineness with a ball mill, and then calcine them at 800-900℃ and then leach them to obtain a lithium-containing solution. This method is highly practical and can be applied to almost all lithium minerals, but it consumes a lot of energy for evaporation, has a low lithium recovery rate (about 67%), and has a large amount of slag (42 tons of slag / ton of product).

[0005] For example, Yan et al. calcined a mixture of lepidolite, calcium chloride and sodium chloride at 880°C, and then 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] The Chinese patent CN115466853A application document discloses a method and device for extracting lithium from lithium mica by vertical grinding and leaching, which mainly uses sulfuric acid method to extract lithium, and mixes lithium ore and 50% to 80% concentrated sulfuric acid at 150 to 180°C for roasting. This method has obvious disadvantages, including high energy consumption, large acid consumption, and high consumption of soda ash in subsequent neutralization and slurry adjustment, which is costly.

[0007] In summary, the industrial lithium extraction process is either a method of roasting at high temperature and then leaching and crystallizing, or involves the use of concentrated sulfuric acid, sulfates, limestone, chlorides and other agents, which has the characteristics of high energy consumption, unfriendly to the environment, strong corrosion to equipment, and high requirements for equipment. In addition, 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, magnesium, aluminum and other elements derived from the structure of the lithium ore itself. Silicon is considered to be the most promising negative electrode material for lithium-ion batteries. Its theoretical specific capacity is far superior to commercial graphite negative electrode materials (4200vs.372mAh / 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] In order 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 a silicon element, and converting the lithium into a form that is easy to leached, to obtain a reduction product, and subjecting the reduction product to lithium ion leaching treatment to obtain a lithium-rich leaching solution 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 performing solid-liquid separation to obtain a lithium-rich water leaching solution and a first solid; or, subjecting the reduction product to a first dilute acid leaching, and performing solid-liquid separation to obtain a lithium-rich acid leaching solution 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 value is adjusted, the temperature is raised and stirred for a period of time to perform dynamic crystallization, and then static crystallization is performed 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 causes the lithium-containing mineral to undergo a reduction reaction under the action of a reducing agent. During the reduction reaction, the reducing agent strongly captures oxygen from the mineral structure and destroys the mineral structure, reducing silicon dioxide to silicon element, and converting lithium into a form that is easy to leached, effectively avoiding the use of high-concentration acid and alkali, high-temperature and high-pressure roasting to destroy the mineral structure. In the lithium extraction process after the metal thermal reduction, in order to break and depolymerize the reduction product to expose the lithium-containing particles, the reduction product is ball-milled. Subsequently, nearly half of the mass of lithium can be extracted by water leaching the reduction product. Since 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 during the reduction process, the aluminum element is in the form of aluminum element and aluminum oxide, and the iron element is in the form of iron, iron oxide and iron silicide. The above substances are all insoluble in water, while lithium and lithium oxide are both easily soluble in water. Therefore, lithium can be dissolved during water leaching, but magnesium and aluminum are difficult to dissolve, so that the magnesium-lithium (mass) ratio of the water leaching liquid is extremely low, which is conducive to the separation of magnesium and lithium. After water leaching, acid leaching is used to leach out most of the remaining lithium. Although the acid leaching solution contains a large amount of magnesium, aluminum, lithium and other ions at this time, magnesium and aluminum will enter the layered polymetallic hydroxide crystals through the preparation of layered polymetallic hydroxide crystals in the next step. Lithium does not enter the layered polymetallic hydroxide crystals due to the mismatch between its price and magnesium, but enters the supernatant of the layered polymetallic hydroxide crystals in the form of ions. At this time, the supernatant contains extremely low magnesium content and almost no lithium loss, that is, the magnesium-to-lithium ratio of the supernatant is extremely low, 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 insulation 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 insulation 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, lithium mica, iron lithium mica, hectorite, lithium kaolinite, lithium illite, hectorite, lithium chlorite, lithium zeolite and jaddarite.

[0016] Preferably, the metal reducing agent is a 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:(1-5).

[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 or / and 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 requirements for equipment and low resource utilization efficiency in the existing lithium ore extraction process, 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, and couples the lithium extraction process with the process of preparing silicon nanomaterials. In the process of the metal reducing agent strongly capturing the mineral structural 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 out by water leaching, acid leaching or direct acid leaching of the product, and 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 the 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 column corresponds 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 multimetal hydroxide prepared in Example 1 of the present invention.

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

[0035] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be noted that if the specific conditions are not specified in the examples, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased from the market.

[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 lithium mica is large, and the lamellae are difficult to fully expose, and the metal thermal reduction reaction will be insufficient. Therefore, it is necessary to crush the lithium mica in advance to reduce the particle size. Specifically, the lithium mica is placed in a planetary ball mill at a speed of 600 rpm for 3 hours to obtain a ball-milled lithium mica with a fine particle size;

[0040] (2) 10 g of fine-grained lepidolite crushed by ball milling, 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, heated to 750 °C under an argon atmosphere and kept warm for 5 h. The reduction product was then added to a ball mill filled 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 first solid was repeatedly immersed in water for five times, and solid-liquid separation was performed to obtain a first solid and five portions of 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, and then separating the solid and the liquid 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) Lithium-rich acid leaching process: The lithium-rich acid leaching solution and the 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 at room temperature, 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, followed by static crystallization 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 and centrifuged several times until the pH of the supernatant is close to neutral, and dried at 80°C to obtain a magnesium-aluminum layered double metal 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 above alkali solution was prepared by adding 3.20 g of sodium hydroxide and 1.70 g of sodium carbonate into a beaker and adding 200 mL of water to dissolve.

[0047] like Figure 2 As shown, the lithium extraction efficiency of each step of Example 1 of the present invention and the magnesium-lithium ratio of the lithium-rich liquid. After metal thermal reduction and ball milling, lithium can be leached out in five water leachings of the reduced product, and the content of leached lithium gradually decreases with the increase in the number of leaching times. 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%, and because the water solubility of magnesium oxide and magnesium is low, the magnesium-lithium ratio of the water leaching solution is extremely low (all less than 1), which is conducive to the 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 magnesium-lithium ratio of the solution is greatly reduced by removing magnesium and aluminum through the subsequent preparation of layered multimetal hydroxides, and the total lithium extraction rate can reach 93.4%.

[0048] like Figure 3 , which is an X-ray diffraction diagram of 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 picture of the nano-silicon prepared in Example 1 of the present invention. It can be seen from the picture 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 button batteries for battery cycle performance. As can be seen from the figure, the material has good cycle performance as a negative electrode for lithium batteries. -1 After 500 cycles at a current density of 850 mAh g -1 Specific capacity.

[0051] like Figure 6 As shown, it is the X-ray diffraction pattern of the magnesium aluminum layered double metal 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 metal hydroxide are obvious and the physical phase is single.

[0052] like Figure 7 As shown, it is a scanning electron microscope picture 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 and ball milled at 800 rpm for 2 hours to obtain fine-grained spodumene;

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

[0057] (3) taking 7.5 g of the reduction product after ball milling and placing it in a beaker for water immersion, adding 200 mL of deionized water, and ultrasonically immersing it for 1 h, solid-liquid separation is performed to obtain a first solid and a lithium-rich water immersion solution, and the first solid is repeatedly immersed in the water for seven times, and solid-liquid separation is performed to obtain a 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 hours, and then separating the solid and the liquid 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) Lithium-rich acid leaching process: Add 2.12g of magnesite to the lithium-rich acid leaching solution to supplement the magnesium source and dissolve it. At room temperature, add the above lithium-rich acid leaching solution and alkali solution drop by drop into the same beaker pre-filled with 135mL of deionized water through a pH automatic liquid adding machine, and maintain vigorous mechanical stirring and constant pH (pH = 9 ± 0.2). 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 dried at 80°C to obtain magnesium-aluminum layered double metal hydroxide, and the total lithium extraction rate is 89.3%.

[0061] The above alkali solution was prepared by adding 4.60 g of sodium hydroxide and 2.44 g of sodium carbonate into a beaker and then adding 200 mL of water to dissolve.

[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, heated to 700 °C under an argon atmosphere and kept warm for 5 h. The reduction product was then added to a ball mill filled with nitrogen, and the ball mill was placed in a planetary ball mill and ball milled at 350 rpm for 1 h.

[0065] (2) taking 9.20 g of the ball-milled reduction product and placing it in a beaker for water immersion, adding 200 mL of deionized water, and magnetically stirring for 1 h, solid-liquid separation was performed to obtain a first solid and a lithium-rich water immersion solution, and the first solid was repeatedly immersed in water 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 6 wt.% sulfuric acid solution and stirring for acid leaching for 1 hour, and then separating the solid and the liquid 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) Lithium-rich acid leaching process: 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 lithium-rich acid leaching solution and the alkali 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 2 hours, followed by static crystallization at 140°C in an oven for 15 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 calcium aluminum layered double metal hydroxide, and the total lithium extraction rate is 91.2%.

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

[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 warm for 5 h. The reduction product was then added to a ball mill filled with nitrogen, and the ball mill was placed in a planetary ball mill and ball milled at 350 rpm for 1 h.

[0073] (2) taking 13.40 g of the ball-milled reduction product and placing it in a beaker for water immersion, adding 200 mL of deionized water, and magnetically stirring for 1 h, solid-liquid separation was performed to obtain a first solid and a lithium-rich water immersion solution, and the first solid was repeatedly immersed in water 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, and then separating the solid and the liquid 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) Lithium-rich acid leaching process: 1.67g of magnesite 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 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 2 hours, followed by static crystallization at 140°C in an oven for 15 hours; after the crystallization is completed, the solid-liquid mixture in the beaker is centrifuged, and the solid is washed with water and centrifuged several times until the pH of the supernatant is close to neutral, and dried at 80°C to obtain zinc-magnesium-aluminum layered trimetallic hydroxide, and the total lithium extraction rate is 92.5%.

[0077] The above 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, heated to 750 ° C under an argon atmosphere and kept warm for 5 h. The reduction product was then added to a ball mill filled with nitrogen, and the ball mill was placed in a planetary ball mill and ball milled at 350 rpm for 1 h.

[0081] (2) taking 7 g of the reduction product after ball milling and placing it in a beaker for dilute acid leaching, adding 200 mL of 3.6 wt.% HCl, and magnetically stirring for 1 h, and then separating the solid and the liquid 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: 1.24 g of 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 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 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 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] Comparative Example 1: 0.5g of magnesium powder cannot completely reduce 10g of lithium mica. At this time, the reaction does not fully destroy the structure of lithium mica, so that the lithium in its octahedral structure cannot be leached, which greatly reduces the lithium extraction rate. The total lithium extraction rate is only 27.2%. The XRD spectrum of the solid obtained by acid leaching reduction product contains characteristic diffraction peaks of lithium mica, quartz, and silicon, which also indicates insufficient reduction and greatly reduces the yield of silicon. Therefore, the amount of magnesium powder needs 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 Mg / Li ratio is 72. Too high a Mg / Li ratio will affect the further extraction of lithium. Therefore, the pH needs to be adjusted to a suitable 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 and the reduction product (Mg2Si in the reduction product) react violently during acid leaching to generate silane gas, produce a bang, release a large amount of heat and a large number of bubbles, making the resulting nano-silicon agglomeration phenomenon more serious. And because the molar amount of hydrochloric acid used is relatively high, a large amount of alkali neutralizing acid needs to be added to achieve the target pH when preparing magnesium-aluminum layered double metal hydroxides, which consumes a large amount of reagents and water and is costly; the salinity of the wastewater after neutralization is high and is not environmentally friendly. Therefore, it is necessary to select a suitable acid concentration.

[0097] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A method for simultaneously extracting lithium and silicon from lithium-containing minerals, characterized in that: The method includes: The lithium- and silicon-containing mineral is subjected to a reduction reaction under the action of a metal reducing agent, the silicon-containing compound is reduced to silicon element, and the lithium is converted into a form that is easy to be leached, thereby obtaining a reduction product, and the reduction product is subjected to lithium ion leaching treatment to obtain a lithium-rich leaching solution and a solid; The lithium ion leaching treatment comprises: subjecting the reduction product to atmosphere ball milling in an inert gas atmosphere, leaching lithium ions by water leaching, and separating the solid from the 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 from the liquid to obtain a lithium-rich acid leaching solution and a first solid A; The first solid is subjected to a first dilute acid leaching to leach lithium ions, and the solid-liquid is separated 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 treatment to obtain a silicon nanomaterial; or the first solid A is subjected to a second dilute acid washing and water washing treatment to obtain a silicon / silicon dioxide nanomaterial; The lithium-rich acid leachate or the lithium-rich acid leachate and the natural mineral are mixed and then added dropwise to water together with an alkaline solution, stirred and pH adjusted, heated and stirred for a period of time to perform dynamic crystallization, and then static crystallization to crystallize the layered multi-metal 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 multimetal 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 inert gas; the temperature of the reduction reaction is 600-1000° C., and the insulation time is 1-20 hours; 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 to 20%; the mass concentration of the second dilute acid is 1 to 20%; And / or, the pH is 6.5-13.

4. The method for simultaneously extracting lithium and silicon from lithium-containing minerals according to claim 1, characterized in that: The lithium-containing mineral is selected from any one or more of spodumene, petalite, eucryptite, lithium mica, iron lithium mica, hectorite, lithium kaolinite, lithium illite, hectorite, lithium chlorite, lithium zeolite and jaddarite.

5. 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; the metal powder is selected from any one or more of magnesium, aluminum, zinc, sodium, potassium and calcium.

6. 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).

7. 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.

8. The method for simultaneously extracting lithium and silicon from lithium-containing minerals according to claim 1, characterized in that: 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 pickling time 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.

9. The method for simultaneously extracting lithium and silicon from lithium-containing minerals according to claim 1, characterized in that: The natural mineral is selected from any one or more of dolomite, magnesite and limestone.

10. 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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