CN113528860A

CN113528860A - Method for efficiently extracting lithium from clay type lithium ore by using pulse voltage

Info

Publication number: CN113528860A
Application number: CN202110790768.3A
Authority: CN
Inventors: 何利华; 赵中伟; 雷云涛; 孙丰龙; 刘旭恒; 陈星宇; 李江涛
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2021-07-13
Filing date: 2021-07-13
Publication date: 2021-10-22
Anticipated expiration: 2041-07-13
Also published as: CN113528860B

Abstract

The invention belongs to the field of electrochemical lithium extraction, and particularly relates to a method for efficiently extracting lithium from clay type lithium ores by using pulse voltage, which comprises the following steps: step 1, establishing an anode area and a cathode area on two sides of clay type lithium ore, inserting an anode into the anode area, and inserting a cathode into the cathode area; adding an intercalating agent to the vicinity of the anode; and 2, applying pulse voltage to the anode and the cathode, and driving lithium ions in the interlayer region of the clay type lithium ore to migrate along the direction of an electric field by utilizing the formed external electric field so as to gradually separate from mineral particles, enter and enrich in a cathode region. The method has the advantages that the method can directly extract lithium without pretreatment such as roasting and the like and strong acid, high temperature and high pressure environment, and is energy-saving, environment-friendly, simple to operate, green and clean.

Description

Method for efficiently extracting lithium from clay type lithium ore by using pulse voltage

Technical Field

The invention belongs to the field of electrochemical lithium extraction, and particularly relates to a method for efficiently extracting lithium from clay type lithium ores by using pulse voltage.

Background

Lithium, as an important energy strategic metal, plays a significant role in the fields of energy storage/power batteries, nuclear energy utilization, metal materials, and the like. Under the promotion of market demand, scientific and technological development and other multifactorial factors, the research hot tide for geological exploration, development and utilization of lithium ore resources is promoted all over the world.

Solid lithium ores are mainly of two types, pegmatite type and clay type. The industrial development of pegmatite-type spodumene and lepidolite is increasingly mature, and the main process is to roast the mineral at the high temperature of 800-1200 ℃ to activate and transform the mineral, and then leach lithium by sulfuric acid for producing lithium salt products.

In clay-type lithium ores, lithium is generally present in clay-type minerals such as montmorillonite, saponite, chlorite, and the like. Such as carbonate type clay type lithium ore, lithium is mainly present in the interlaminar region of the montmorillonite crystal structure of the clay mineral. Because lithium ions are in the mineral crystal and not adsorbed on the surface of mineral particles, direct lithium extraction is difficult to achieve by adopting a leaching/soaking mode. For example, when carbonate clay type lithium ore is leached with sulfuric acid, the leaching rate of lithium is only about 2%.

In the prior art, in order to effectively leach the clay ore, high-temperature roasting and activating treatment needs to be carried out on the clay ore, and then leaching of lithium is realized by using auxiliary agents such as sulfuric acid and the like. For example, the lithium Sonora mineral in Mexico is prepared by using sodium sulfate as an auxiliary agent, roasting at 950 ℃ and leaching with sulfuric acid to obtain Li₂SO₄The leachate is purified and then used for preparing battery grade Li₂CO₃And (5) producing the product. For another example, chinese patent 202010684178.8 discloses a method for extracting lithium from lithium-containing clay, which is to mix and granulate lithium-containing clay, calcium carbonate, sodium sulfate and potassium sulfate, calcine at 900-1100 ℃, and then extract lithium. Chinese patent CN 110358934B discloses a method for extracting lithium from carbonate clay type lithium oreThe method is carried out. The method comprises the steps of roasting and activating clay ore at the temperature of 450-800 ℃, and then leaching by using a ferric trichloride solution.

Besides the high-temperature roasting method, concentrated sulfuric acid can be used for carrying out full-rock decomposition leaching on the clay type lithium ore under the conditions of high temperature and high pressure (180-250 ℃). At present, except that the American Keyton valley (Clayton Valley) and Big Sandy (Big Sandy) lithium ores can be leached out by hot acid leaching directly, the wet process of most of the other lithium ores can realize the effective leaching of lithium by adopting high-concentration sulfuric acid at high temperature and high pressure (200 ℃). For another example, chinese patent 202010472603.7 discloses a method for leaching lithium from a lithium-containing clay rock with high efficiency. The core of the method is that the raw ore is firstly crushed to be less than 2mm, then mixed with concentrated sulfuric acid for size mixing, and then is subjected to heat treatment and curing in a muffle furnace at the temperature of 150 ℃ and 210 ℃ for 1-4 hours, and the clinker is soaked in water at the temperature of 80 ℃. The concentrated sulfuric acid is used for curing at high temperature and high pressure or the concentrated sulfuric acid, the crystal structure of the mineral is completely destroyed, and a large amount of impurities such as aluminum, magnesium, potassium and the like are leached, so that the subsequent separation and purification of lithium are challenged. Furthermore, the use of concentrated sulfuric acid poses serious challenges to equipment safety.

Due to the low grade of clay type lithium ore, the ore dressing and enrichment are difficult. Therefore, the problems of large treatment capacity and reagent dosage, high energy consumption, high cost, large slag quantity, high pollution and the like exist no matter the roasting process or the concentrated sulfuric acid high-temperature leaching process is adopted.

The main reason for analyzing the disadvantages of the above method is that, unlike rare earth minerals in which metal elements exist on the crystal surface, lithium is mainly present in the montmorillonite crystal structure of clay minerals in clay-type lithium minerals. Such an ion existence state makes it difficult to leach lithium element in the conventional acid leaching manner at normal temperature and pressure. High temperature calcination activation or high temperature and high pressure conditions are required.

In further studies of the inventors, most of the lithium-containing clay minerals have ion conductivity. Such as hectorite, is nearly comparable in ionic conductivity to liquid electrolytes. Meanwhile, most of the clay minerals containing lithium are layered aluminosilicate, and part of Si in Si-O tetrahedron is easy to occur in the process of mineralization of the clay minerals⁴⁺Is covered with Al³⁺Substituted, part of Al in Al-O octahedron³⁺Is coated with Mg²⁺Substitution results in the creation of negative charges in the mineral lattice structure. To maintain charge neutrality, clay minerals attract Li in the environment⁺The ions enter the interlaminar domain of the crystal structure or are adsorbed on the surface of the mineral particles.

Since the driving force for extracting lithium is an external electric field, the manner of applying voltage has an influence on the efficiency of extracting lithium. When constant voltage electrolysis is used, a thicker diffusion layer is easily formed at the mineral particle/solution interface, so that the concentration of cations in the intercalant on the surface of the mineral particle is reduced to generate concentration polarization, the current efficiency is reduced, and the extraction rate of lithium is limited. When the pulse voltage is adopted, cations in the intercalating agent can diffuse and replenish to the surface of the mineral particles in the turn-off time period (no voltage output time period), and when the next turn-on time comes, the concentration of the cations in the intercalating agent on the surface of the mineral particles is recovered, so that the rapid extraction of lithium can be realized under higher current density.

Based on the above, the inventor proposes a method for extracting lithium from clay-type lithium ore by using the action of an electric field and directly using pulse voltage without advanced treatment and leaching.

Disclosure of Invention

The invention aims to solve the problem of green and efficient extraction of the existing clay type lithium ore and aims to provide a method for directly and efficiently extracting lithium from the clay type lithium ore by electrochemically forcing lithium ions. The problems of large slag quantity, high cost, large pollution and the like of the traditional lithium extraction process of the lithium ores are solved.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for efficiently extracting lithium from clay type lithium ores by using pulse voltage, which comprises the following steps:

step 1, establishing an anode area and a cathode area on two sides of clay type lithium ore, inserting an anode into the anode area, and inserting a cathode into the cathode area; adding an intercalating agent to the vicinity of the anode, wherein the intercalating agent is an agent capable of providing cations, and during the extraction process, the cations in the intercalating agent enter the clay-type lithium ore to replace lithium ions;

and 2, applying single pulse voltage to the anode and the cathode, and driving lithium ions in the interlayer region of the clay type lithium ore to migrate along the direction of an electric field by utilizing the formed external electric field so as to gradually separate from mineral particles, enter and enrich in a cathode region.

To ensure the extraction rate of lithium during the process, the applied electric field strength should be set within a reasonable range. Theoretically, the strength of the external electric field can be selected according to actual needs; however, considering that the application of too high electric field intensity is favorable for the rapid migration of ions, the energy consumption is relatively large; applying too low an electric field strength is beneficial to ensure lithium selectivity and current efficiency during electrolysis, but the rate of lithium extraction is slower.

When constant voltage electrolysis is used, a thicker diffusion layer is easily formed at the mineral particle/solution interface, so that the concentration of cations in the intercalant on the surface of the mineral particle is reduced to generate concentration polarization, the current efficiency is reduced, and the extraction rate of lithium is limited. Experiments show that when the constant electric field intensity is adopted for extraction, the electric field intensity of an external electric field is 0.1-2.0V/cm.

When the pulse voltage is adopted, cations in the intercalating agent can diffuse and replenish to the surface of the mineral particles in the turn-off time period (no voltage output time period), and when the next turn-on time comes, the concentration of the cations in the intercalating agent on the surface of the mineral particles is recovered, so that the rapid extraction of lithium can be realized under higher current density.

For the pulse electrolysis lithium extraction process of the clay type lithium ore, the electric field intensity of the clay layer and the duty ratio of the pulse voltage have obvious influence on the extraction effect of lithium. The electric field intensity is too high, the electroosmotic flow in the clay layer is mainly the migration of solution phase ions among mineral particles, and the current efficiency is lower at the moment. The fact that the duty ratio of the pulse voltage is too low means that the voltage application time is too short, the corresponding lithium extraction time is also short, the average current in the process is small, and the rapid extraction of lithium is not facilitated; if the duty ratio is too high, the voltage turn-off time is too short, which is not beneficial to eliminating concentration diffusion. Compared with constant voltage, the advantage of adopting pulse voltage is that the lithium content in the slag is lower on the premise of short time consumption and same mineral production compared with the premise of the same extraction amount.

Preferably, the unidirectional pulse voltage is adopted to enable the electric field intensity between the anode and the cathode to be 0.1-5.0V/cm.

Specifically, the duty ratio of the unidirectional pulse voltage is 30% -80%.

In order to make the process of extracting lithium by pulse electrolysis smoothly, the whole circuit must form a complete closed circuit. Therefore, the clay-type lithium ore is required to have a certain ionic conductivity. Therefore, the moisture content of the clay-type lithium ore is required to be in a certain range, and for minerals having a low moisture content and an ionic conductivity that does not satisfy the requirements, the minerals need to be subjected to a pretreatment operation before electrolysis.

Further, in the step 1, a conductive aid is added into the clay-type lithium ore, wherein the conductive aid is water or a conductive solution.

Preferably, the conductive aid is water or an aqueous solution of an intercalator cation donor.

Further research shows that, on the one hand, the water content is too low to facilitate the electromigration of lithium ions in the lithium-containing clay mineral, which leads to difficulty in the electrolytic process. On the other hand, a clay layer having an excessively high water content has fluidity, and the heap soil is easily collapsed during heap leaching, and the excessively high water content enhances ionic conductivity in the solution phase, and current efficiency is lowered.

Therefore, the moisture content of the lithium-containing clay mineral in the step 2 is preferably 10 to 60% by mass fraction.

Further, in the step 1, a filter layer is further arranged; the filter layer is arranged between the anode area and the clay type lithium ore and/or between the cathode area and the clay type lithium ore.

Further, the cathode region is also provided with a collector, the collector has conductivity, and lithium ions are enriched in the collector.

Further, the intercalation agent and the collecting agent are one or a combination of several of solution, gel and solid.

Further, the number of the anode regions is one or more, and the number of the cathode regions is one or more. The anode regions and the cathode regions may be arranged in a staggered manner with each other on a plane, or the anode regions and the anode regions may be disposed on different horizontal planes.

Preferably, the cathode region is established at a lower level and the anode region is established at an upper level. Therefore, the directional migration of lithium and the entry of cations in the intercalation agent into an ore body can be facilitated, and the dual functions of an electric field and a gravity field are fully utilized to promote the flow and the directional enrichment of lithium.

Preferably, the clay-type lithium ore comprises: one or more of hectorite, lithium-containing vermiculite, lithium-containing mica, lithium-containing chlorite. The reason is that these clay minerals are aluminosilicates having a layered structure, and lithium ions are mainly incorporated in the interlamellar domains of the mineral structure. Such clay minerals have ionic conductivity (e.g., montmorillonite has excellent ionic conductivity, is comparable to liquid electrolytes, and has been studied as solid electrolytes and fast ion conductor materials), and are essentially fast in cation migration in the interlaminar domain of the mineral structure driven by an electric field.

Preferably, the cation provided by the intercalating agent is a soluble cation having better adsorption properties than lithium ions. Research shows that the cation adsorption performance of montmorillonite interlamination domains is as follows from small to large: li⁺<Na⁺<K⁺<NH₄ ⁺<Mg²⁺<Ca²⁺<Sr²⁺<Ba²⁺<Al³⁺<Fe³⁺. Wherein Na⁺、K⁺、Mg²⁺And Ca²⁺Stable property, no toxicity and no harm.

More preferably, the cation provided by the intercalating agent is Na⁺、K⁺、Mg²⁺、Ca²⁺、NH₄ ⁺. The ion has stable property, and is nontoxic and harmless. By using compounds containing K⁺、Mg²⁺、Ca²⁺、NH₄ ⁺The intercalation agent can also play a role in improving soil.

More preferably, the cation donor in the intercalating agent is soluble alkali goldAqueous solutions of the metal compound or/and the alkaline earth metal compound or gels thereof. Wherein the alkali metal compound is NaCl, KCl, NaNO₃、KNO₃、Na₂SO₄、K₂SO₄、Na₂CO₃、K₂CO₃、NaHCO₃、KHCO₃Any one or more of NaOH and KOH; the alkaline earth metal compound is MgCl₂、CaCl₂、Mg(NO₃)₂、Ca(NO₃)₂、MgSO₄、Mg(HCO₃)₂、Ca(HCO₃)₂Any one or more of them.

During the electrolysis process, H is continuously generated on the surface of the insoluble anode⁺To avoid the conversion of the intercalating agent to a strongly acidic one, it is further preferred that the anion of the cation donor pair of the intercalating agent is a soluble OH^-、CO₃ ^2-、HCO₃ ^-(ii) a Or additionally adding a pH regulator into the intercalating agent, wherein the pH regulator is a soluble strong acid weak base salt, a soluble alkali or a strong acid weak base salt and an alkali which can be dissolved in acid.

Preferably, the pH regulator is a poorly soluble carbonate or a base. More preferably, MgCO is adopted as the pH agent₃、CaCO₃、Mg(OH)₂、Ca(OH)₂One or a mixture of several of them in any proportion. pH regulator and H⁺Reaction with simultaneous dissolution of Mg produced²⁺And Ca²⁺And the lithium ions enter the soil under the action of an electric field, and the intercalated lithium ions enter the interlayer domain of the lithium-containing clay mineral to realize the replacement and extraction of the lithium.

Further, the insoluble carbonate is taken from calcite, dolomite and magnesite.

Further, in the step 2, in order to maintain the continuous process of the electrolytic lithium extraction, the intercalation agent needs to be added periodically, or the concentration of the intercalation agent is maintained within a certain range.

Preferably, the concentration of the cation donor in the intercalating agent is 0.005-2.0 mol/L.

The function of the collector in the cathode region is to conduct electricity as a supporting electrolyte solution and to concentrate lithium ions migrating from the lithium-containing clay mineral.

Preferably, the collector is an aqueous solution of an alkali metal salt. More preferably, the collector is Na⁺、K⁺A salt or an alkali soluble aqueous solution. More preferably, the collecting agent is NaCl, KCl, NaNO₃、KNO₃、Na₂SO₄、K₂SO₄、Na₂CO₃、K₂CO₃、NaHCO₃、KHCO₃One or more of (a). The reason is that sodium ions and potassium ions in the collector are easily separated from lithium ions which are subsequently enriched.

Further, the initial concentration of the alkali metal salt in the collecting agent is 0.01-1.0 mol/L.

Further, along with the proceeding of the electrolysis process, the concentration of lithium ions in the collector can be gradually increased, when the lithium ions are enriched to a certain concentration, the original collector is extracted for subsequent treatment, and new collector is injected into the cathode region again to continue the electrolysis and lithium extraction.

Further, the anode is a carbon material anode, a metal anode or a composite material anode; the cathode is a carbon material cathode, a metal cathode or a composite material cathode.

The carbon material anode comprises graphite, carbon fiber cloth and carbon felt; the metal anode comprises inert metal, iron, aluminum, magnesium and the like, and the composite material anode comprises a dimensionally stable anode coated with ruthenium, titanium and the like.

The carbon material cathode comprises graphite, carbon fiber cloth, carbon felt, the metal cathode comprises stainless steel or the composite material cathode comprises a coating nickel-based alloy.

The invention has the beneficial effects that:

1. the direct extraction of the clay type lithium ore can be realized under the electrochemical action, the pyrogenic process roasting process of the ore is omitted, and the energy conservation and environmental protection are realized;

2. strong acid is not needed in the extraction process, high temperature and high pressure do not exist, and the method is energy-saving and environment-friendly;

2. the clay mineral lithium extraction process under the electric field strengthening effect has selectivity and high efficiency, and the lithium-containing mineral has basically unchanged properties after lithium extraction, is easy to treat and is green and environment-friendly;

3. the extraction efficiency is higher than that of constant voltage by adopting pulse voltage.

4. The extraction of lithium and the introduction of beneficial cations can improve the performance of clay slag.

5. The method can be used for slot leaching or heap leaching of clay type lithium ore, and can also be used for directly leaching in situ to reduce the cost.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments are briefly introduced below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and therefore should not be considered as limiting the scope. For a person skilled in the art, without inventive effort, further figures can be obtained from these figures.

FIG. 1 is a schematic diagram of the in situ extraction operation of the present invention;

FIG. 2 is another schematic diagram of the operation of the present invention for in situ extraction;

FIG. 3 is a schematic diagram of the operation of the tank leaching extraction of the present invention.

In the figure, 1-anode region, 2-intercalation agent, 3-anode, 4-clay type lithium ore, 5-cathode region, 6-collecting agent and 7-cathode;

11-anode compartment, 12-leaching agent, 13-anode, 14-cathode compartment, 15-supporting electrolyte solution, 16-cathode, 17-mineral area filled with lithium-containing clay mineral, 18-filter layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

The present invention will be described in further detail with reference to examples.

Example 1

Using an electrolytic cell as shown in FIG. 3, Li was added₂Filling lithium-containing clay ore with O content of 0.52% into mineral area of the electrolytic cell, sealing both ends with sponge, and injecting 1L of Na containing 0.5mol/L into anode chamber₂CO₃The cathode chamber is filled with 1L of aqueous solution containing 0.5mol/L NaCl as supporting electrolyte solution, and the anode chamber and the cathode chamber are respectively inserted with a graphite anode and a stainless steel cathode.

And applying unidirectional pulse voltage between the anode and the cathode, wherein the pulse amplitude is 50V (the corresponding electric field intensity is 2.5V/cm), and the duty ratio is 30%.

Adding Na to the leaching agent and the supporting electrolyte solution respectively during electrolysis₂CO₃And HCl, so that the pH value of the HCl and the pH value of the HCl are controlled within the range of 6-13.

After 72 hours of continuous electrolysis, the lithium concentration in the supporting electrolyte solution reached 506 mg/L.

Example 2

Using an electrolytic cell as shown in FIG. 3, Li was added₂Lithium-containing clay mineral with 0.33% of O content and calcite (CaCO)₃) Uniformly mixing the components according to the mass ratio of 100:1, wetting the mixture by water, filling the pretreated lithium-containing clay ore into an ore area of an electrolytic cell, plugging two ends of the pretreated lithium-containing clay ore by sponges, and injecting 1L of the lithium-containing clay ore containing 0.1mol/LCaCl into an anode chamber₂And 0.5mol/L CaCO₃The suspension is used as a leaching agent, and 1L of the suspension containing 0.05mol/LK is injected into the cathode chamber₂SO₄+0.05mol/L KHCO₃The anode chamber and the cathode chamber are respectively inserted with a carbon fiber cloth anode and a nickel-based coating cathode.

And applying unidirectional pulse voltage between the anode and the cathode, wherein the pulse amplitude is 8V (the corresponding electric field intensity is 0.4V/cm), and the duty ratio is 60%.

After continuous electrolysis for 100h, the lithium concentration in the supporting electrolyte solution reached 245 mg/L.

Example 3

Using an electrolytic cell as shown in FIG. 3, Li was added₂Lithium-containing clay mineral with 0.45% of O contentFilling into mineral area of the electrolytic cell, plugging both ends with sponge, injecting 1L MgSO 0.01mol/L into anode chamber₄And 0.5mol/L Mg (OH)₂The suspension is used as a leaching agent, and 1L of the suspension containing 0.01mol/LNa is injected into the cathode chamber₂CO₃+0.05mol/L NaHCO₃The aqueous solution of (a) is used as a supporting electrolyte solution, and a ruthenium-coated titanium plate anode and a graphite cathode are respectively inserted into an anode chamber and a cathode chamber.

And applying unidirectional pulse voltage between the anode and the cathode. In one period, the pulse amplitude I is 100V (corresponding to the electric field intensity of 5.0V/cm), and the pulse width I is 1 ms; the pulse amplitude II was 6V (corresponding to an electric field strength of 0.3V/cm), the pulse width II was 4ms, and stationary for 1ms (from which a duty cycle of 80% was calculated).

After 16h of continuous electrolysis, the lithium concentration in the supporting electrolyte solution reached 122 mg/L.

Example 4

Firstly, 0.1mol/L CaCl is used₂Solution pairing of lithium-containing clay mineral (Li)₂O content of 0.68%) and then filling the pretreated lithium-containing clay ore into a small heap leaching tank of 50cm multiplied by 50 cm. Four same plastic pipes with holes are inserted into four corners of the heap leaching tank, and the plastic pipes are used for injecting a leaching agent and inserting a graphite anode to form an anode chamber. The center of the heap-leaching tank is inserted with a plastic pipe with holes which is sleeved with nylon cloth and is used for injecting supporting electrolyte solution and inserting a graphite cathode to form a cathode chamber. The leaching agent is 2L of CaCl containing 0.1mol/L₂+0.1mol/L Na₂SO₄The solution is pumped between the leachant storage tank and the anode chamber. The supporting electrolyte solution is 2L and contains 0.1mol/L of Na₂SO₄+0.1mol/LNaHCO₃And a solution, wherein the supporting electrolyte solution is transferred between the supporting electrolyte solution storage tank and the cathode chamber through a water pump.

A bi-directional pulsed voltage is applied across the anode and cathode. In one period, the pulse amplitude I was 20V (the formed non-uniform electric field strength was about 0.57V/cm at maximum), the pulse width I was 3ms, followed by rest for 3ms, the pulse amplitude II was 1V (the formed non-uniform electric field strength was about 0.03V/cm at maximum), the pulse width II was 2ms, followed by rest for 2ms (thereby calculating a duty ratio of 50%).

Storage of leaching agent and addition of Ca (OH) during electrolysis₂The pH value is controlled within the range of 7 to 12.

After 24h of the first electrolysis, the lithium concentration in the supporting electrolyte solution had been enriched to 1052 mg/L. At this time, the obtained enriched liquid containing lithium is sent to the lithium extraction process. And simultaneously, replacing the new enrichment solution for second electrolysis.

After 24h of the second electrolysis, the concentration of lithium in the supporting electrolyte solution was enriched to 984 mg/L. At this time, the obtained enriched liquid containing lithium is sent to the lithium extraction process. Meanwhile, the new enrichment solution is replaced to carry out third electrolysis.

After 24h of the third electrolysis, the lithium concentration in the supporting electrolyte solution was enriched to 955 mg/L. At this time, the obtained enriched liquid containing lithium is sent to the lithium extraction process. The enriched solution can be replaced by new enriched solution and electrolysis can be continued.

Comparative example 1

This comparative example differs from example 1 in that: no power is applied. After 72h, the lithium concentration in the supporting electrolyte solution was only 65 mg/L.

Comparative example 2

This comparative example differs from example 2 in that: the electrolysis process is maintained at a constant voltage of 8V. After continuous electrolysis for 100h, the lithium concentration in the supporting electrolyte solution was 203 mg/L.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A method for efficiently extracting lithium from clay type lithium ores by using pulse voltage is characterized by comprising the following steps:

step 1, establishing an anode area and a cathode area on two sides of clay type lithium ore, inserting an anode into the anode area, and inserting a cathode into the cathode area; adding an intercalating agent to the vicinity of the anode, the intercalating agent being an agent capable of providing cations; in the extraction process, cations in the intercalation agent enter an interlayer domain structure of the clay type lithium-containing mineral of the clay type lithium ore to replace lithium ions;

and 2, applying pulse voltage to the anode and the cathode, and driving lithium ions in the interlayer region of the clay type lithium ore to migrate along the direction of an electric field by utilizing the formed pulse external electric field so as to gradually separate from mineral particles, enter and enrich in a cathode region.

2. The method for efficiently extracting lithium from clay-type lithium ore according to claim 1, wherein the cathode region is further provided with a collector having conductivity in which lithium ions are concentrated.

3. The method for extracting lithium from clay-type lithium ore with high efficiency by using pulsed voltage according to claim 1, wherein the intercalating agent and the collecting agent are one or a combination of several of solution, gel and solid.

4. The method for efficiently extracting lithium from clay-type lithium ores according to claim 1, wherein the number of the anode regions is one or more, and the number of the cathode regions is one or more; the anode regions and the cathode regions may be arranged in a staggered manner with each other on a plane, or the anode regions and the anode regions may be disposed on different horizontal planes.

5. The method for extracting lithium from clay-type lithium ore with high efficiency by using pulsed voltage according to claim 1, wherein the cation provided by the intercalating agent is a soluble cation having better adsorption performance than lithium ion.

6. The method of claim 1, wherein the anion of the cation donor pair of the intercalating agent is soluble OH^-、CO₃ ^2-、HCO₃ ^-(ii) a Or additionally adding a pH regulator into the intercalating agent, wherein the pH regulator is a soluble strong acid weak base salt, a soluble alkali or a strong acid weak base salt and an alkali which can be dissolved in acid.

7. The method for efficiently extracting lithium from clay-type lithium ore according to claim 6, wherein the pH regulator is MgCO₃、CaCO₃、Mg(OH)₂、Ca(OH)₂One or a mixture of several of them in any proportion.

8. The method for efficiently extracting lithium from clay-type lithium ore by using pulsed voltage according to claim 1, wherein the step 1 further comprises adding a conductive aid to the clay-type lithium ore, wherein the conductive aid is water or a conductive solution.

9. The method for efficiently extracting lithium from clay-type lithium ore according to claim 1, wherein the collecting agent is Na⁺、K⁺A salt or an alkali soluble aqueous solution.

10. The method for efficiently extracting lithium from clay-type lithium ores by using pulsed voltage according to any one of claims 1 to 9, wherein the electric field intensity of the external electric field is 0.1 to 5.0V/cm, and the pulse duty ratio is 30 to 80%.