Method for extracting lithium carbonate from clay type lithium resource

Abstract

The invention provides a method for extracting lithium carbonate from clay type lithium resources, and relates to the technical field of lithium extraction. The method comprises the following steps: carrying out first mixing on a clay type lithium resource and sodium sulfate, and roasting to obtain a roasted material; the roasted material is subjected to water leaching to obtain first ore pulp; the first ore pulp and sodium hydroxide are secondarily mixed to obtain second ore pulp; carrying out third mixing on the second ore pulp and calcium chloride, and carrying out solid-liquid separation to obtain tempered liquid; carrying out nanofiltration, first reverse osmosis and impurity removal on the conditioned solution to obtain an impurity-removed solution; and carrying out fourth mixing on the impurity-removed solution and the saturated sodium carbonate solution to obtain lithium carbonate. According to the method, sodium sulfate serves as an auxiliary agent to achieve selective efficient extraction of lithium in the clay type lithium ore, then lithium sulfate in second ore pulp is converted into lithium chloride through calcium chloride, and the obtained tempered liquid is suitable for a nanofiltration-reverse osmosis process.

Description

Technical Field

[0001] The present application relates to the technical field of lithium extraction, and in particular to a method for extracting lithium carbonate from clay-type lithium resources. Background Art

[0002] Lithium deposits are mainly divided into three categories: brine type, pegmatite type and clay type. Brine-type lithium resources are mainly concentrated in the "Lithium Triangle" area of ​​South America. Pegmatite-type lithium ores are mainly spodumene and lithium mica, which are widely distributed in Australia, Brazil and other regions. Clay-type lithium resources are mainly distributed in the United States and Mexico. Recently, a large number of clay-type lithium mines have been discovered in southwest my country and are being traded and mined.

[0003] The main clay minerals in North America are montmorillonite and illite, which usually exist in the form of small scaly aggregates with unstable structures. my country's clay-type lithium ores are mainly kaolinite and chlorite, with relatively stable structures. As a result, the lithium extraction process of my country's clay-type lithium ores is more difficult. In addition, since the lithium content in clay-type lithium ores is low and difficult to enrich, the lithium concentration in the leachate is low. The subsequent evaporation and concentration results in high energy consumption, which greatly increases the cost of lithium extraction. Summary of the invention

[0004] The purpose of this application is to provide a method for extracting lithium carbonate from clay-type lithium resources to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solutions: A method for extracting lithium carbonate from clay-type lithium resources, comprising: The clay-type lithium resource and sodium sulfate are first mixed and roasted to obtain a roasted material; The roasted material is subjected to water immersion to obtain a first slurry; The first ore pulp and sodium hydroxide are mixed for a second time to obtain a second ore pulp; The second ore slurry and calcium chloride are subjected to a third mixing and solid-liquid separation to obtain a conditioned liquid; The conditioned liquid is subjected to nanofiltration to obtain a nanofiltration clear liquid; The nanofiltration clear liquid is subjected to a first reverse osmosis to obtain a first reverse osmosis concentrate; The first reverse osmosis concentrated solution is subjected to impurity removal to obtain an impurity-removed solution; The impurity-removed solution and the saturated sodium carbonate solution are mixed for the fourth time to obtain lithium carbonate.

[0006] Optionally, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. The mass of the sodium sulfate is 10%-100% of the mass of the clay-type lithium resource; B. The calcination temperature is 400°C-950°C, and the calcination time is 0.5h-5h.

[0007] Optionally, the calcination temperature is 600° C.-900° C., and the calcination time is 1 h-3 h.

[0008] Optionally, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. The water immersion temperature is 15°C-95°C, and the time is 0.5h-5h; B. The solid-liquid ratio of the water immersion is 1g:(5mL-30mL).

[0009] Optionally, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. The pH value of the second slurry is 6-7; B. the molar amount of the calcium chloride is 0.8 to 1.2 times the molar amount of the lithium ions in the second slurry; C. The temperature of the third mixing is 15°C-95°C, and the time is 0.5h-5h.

[0010] Optionally, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. the nanofiltration includes multi-stage nanofiltration; B. The sodium ion concentration in the nanofiltration clear solution is 0.5 g / L-1.5 g / L; C. The temperature of the nanofiltration is 5°C-50°C; D. The filtration pressure of the nanofiltration is 2Mpa-5Mpa; E. The pH of the nanofiltration clear liquid is 6-7.

[0011] Optionally, the multi-stage nanofiltration includes three-stage nanofiltration; The three-stage nanofiltration comprises: the conditioned liquid is subjected to a first nanofiltration to obtain a first nanofiltration clear liquid and a first nanofiltration concentrated liquid; The first nanofiltration concentrate is subjected to MVR treatment to obtain sulfate; The first nanofiltration clear liquid is subjected to a second nanofiltration to obtain a second nanofiltration clear liquid and a second nanofiltration concentrate; The second nanofiltration clear liquid is subjected to a third nanofiltration to obtain a nanofiltration clear liquid and a nanofiltration concentrate; The second nanofiltration concentrate and the nanofiltration concentrate are returned to the upper stage for treatment in sequence; The sulfate is returned to the first mixing.

[0012] Optionally, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. the first reverse osmosis also obtains a first reverse osmosis clear liquid; The first reverse osmosis clear liquid is subjected to a second reverse osmosis to obtain a second reverse osmosis concentrated liquid and a second reverse osmosis clear liquid; The second reverse osmosis concentrate is returned to an upper stage for treatment; The second reverse osmosis clear liquid is returned for the water immersion; B. The lithium ion concentration in the first reverse osmosis concentrate is 5 g / L-10 g / L.

[0013] Optionally, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. The temperature of the first reverse osmosis and the second reverse osmosis are independently 5°C-50°C; B. The filtration pressure of the first reverse osmosis and the second reverse osmosis are independently 6Mpa-10Mpa; C. The pH of the first reverse osmosis and the second reverse osmosis are independently 6-7.

[0014] Optionally, the molar amount of the sodium carbonate is 1.2 to 1.5 times the molar amount of lithium ions in the solution after impurities are removed.

[0015] Compared with the prior art, the beneficial effects of this application include: The present application provides a method for extracting lithium carbonate from clay-type lithium resources. Sodium sulfate is used as an auxiliary agent. Sodium oxide in sodium sulfate reacts with aluminosilicate in clay minerals, thereby destroying the structure of aluminosilicate and releasing lithium in the aluminosilicate lattice and interlayer. Subsequently, water leaching can be used to achieve selective and efficient extraction of lithium from clay-type lithium ore. The pH value of the first slurry obtained by water leaching is regulated by sodium hydroxide, so that a small amount of impurities such as iron and aluminum in the slurry liquid phase can be removed, and sodium hydroxide does not introduce other impurity ions. The main component of the solution is sodium sulfate. Chloride ions are then introduced into the slurry by calcium chloride, and calcium ions are precipitated into the slag in the form of calcium sulfate. After liquid-solid separation, a mixed solution similar to sodium sulfate and lithium chloride can be formed. The chloride ions and lithium ions in the solution are both monovalent ions and are easily separated from sodium sulfate by nanofiltration, thereby obtaining a nanofiltration clear solution containing lithium chloride. The lithium-containing nanofiltration clear solution (low-lithium solution) is then enriched with lithium by a reverse osmosis process, and a high-concentration first reverse osmosis concentrated solution (lithium-rich solution) can be obtained without evaporation and concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0017] Figure 1 This is a flow chart of the method for extracting lithium carbonate from clay-type lithium resources provided in Example 1. DETAILED DESCRIPTION

[0018] As used herein: "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0019] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0020] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0021] In these examples, parts and percentages are by mass unless otherwise indicated.

[0022] "Mass parts" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass parts of component A are a parts and the mass parts of component B are b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0023] “And / or” is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0024] The present application adopts the following technical solution: A method for extracting lithium carbonate from clay-type lithium resources, comprising: The clay-type lithium resource and sodium sulfate are first mixed and roasted to obtain a roasted material; The roasted material is subjected to water immersion to obtain a first slurry; The first ore pulp and sodium hydroxide are mixed for a second time to obtain a second ore pulp; The second ore slurry and calcium chloride are subjected to a third mixing and solid-liquid separation to obtain a conditioned liquid; The conditioned liquid is subjected to nanofiltration to obtain a nanofiltration clear liquid; The nanofiltration clear liquid is subjected to a first reverse osmosis to obtain a first reverse osmosis concentrate; The first reverse osmosis concentrated solution is subjected to impurity removal to obtain an impurity-removed solution; The impurity-removed solution and the saturated sodium carbonate solution are mixed for the fourth time to obtain lithium carbonate.

[0025] In some optional embodiments, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. The mass of the sodium sulfate is 10%-100% of the mass of the clay-type lithium resource; Exemplarily, the mass of sodium sulfate may be 10%, 15%, 25%, 35%, 45%, 55%, 65%, 75%, 85%, 95%, 100% or any value between 10% and 100% of the mass of the clay-type lithium resource; It should be noted that when the mass of sodium sulfate is 10%-100% of the mass of clay-type lithium resources, when it is lower than 10%, most of the clay mineral structure has not dissociated, resulting in a low lithium extraction rate. When the sodium sulfate content exceeds 100%, the sodium concentration in the liquid after conditioning is high, causing greater pressure in the subsequent nanofiltration process and reducing the service life of the nanofiltration membrane.

[0026] B. The calcination temperature is 400°C-950°C, and the calcination time is 0.5h-5h.

[0027] Exemplarily, the calcination temperature can be 400°C, 450°C, 550°C, 650°C, 750°C, 850°C, 950°C or any value between 400°C and 950°C, and the calcination time can be 0.5h, 1.5h, 2.5h, 3.5h, 4.5h, 5h or any value between 0.5h and 5h.

[0028] In some optional embodiments, the calcination temperature is 600° C.-900° C., and the calcination time is 1 h-3 h.

[0029] Exemplarily, the calcination temperature can be 600°C, 620°C, 640°C, 660°C, 680°C, 700°C, 720°C, 740°C, 760°C, 780°C, 800°C, 820°C, 840°C, 860°C, 880°C, 900°C or any value between 600°C and 900°C, and the calcination time can be 1.2h, 1.4h, 1.6h, 1.8h, 2.0h, 2.2h, 2.4h, 2.6h, 2.8h, 3.0h or any value between 1h and 3h.

[0030] It should be noted that when the roasting temperature is 600℃-900℃ and the roasting time is 1h-3h, too low temperature and too short time will lead to incomplete destruction of the aluminosilicate structure and low lithium release and extraction rate, while too high temperature and too long time will cause a large amount of sodium to enter the slag, and the energy consumption of the roasting process will increase, thereby increasing costs.

[0031] In some optional embodiments, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. The water immersion temperature is 15°C-95°C, and the time is 0.5h-5h; Exemplarily, the water immersion temperature may be 15°C, 25°C, 35°C, 45°C, 55°C, 65°C, 75°C, 85°C, 95°C or any value between 15°C and 95°C, and the time may be 0.5h, 0.8h, 1.2h, 1.8h, 2.2h, 2.8h, 3.2h, 3.8h, 4.2h, 4.8h, 5h or any value between 0.5h and 5h; B. The solid-liquid ratio of the water immersion is 1g:(5mL-30mL).

[0032] Illustratively, the solid-to-liquid ratio of the water immersion can be 1 g:5 mL, 1 g:8 mL, 1 g:12 mL, 1 g:18 mL, 1 g:22 mL, 1 g:28 mL, 1 g:30 mL or any value between 1 g:(5 mL-30 mL).

[0033] In some optional embodiments, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. The pH value of the second slurry is 6-7; Exemplarily, the pH value of the second slurry may be 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7 or any value between 6 and 7; It should be noted that when the pH value of the second slurry is 6-7, the corrosion of the solution to the nanofiltration membrane and the reverse osmosis membrane is reduced, thereby increasing the service life of the membrane.

[0034] B. the molar amount of the calcium chloride is 0.8 to 1.2 times the molar amount of the lithium ions in the second slurry; Optionally, the molar amount of calcium chloride may be 0.8 times, 0.9 times, 1 times, 1.1 times, 1.2 times, or any value between 0.8 times and 1.2 times the molar amount of lithium ions in the second slurry; C. The temperature of the third mixing is 15°C-95°C, and the time is 0.5h-5h.

[0035] Exemplarily, the temperature of the third mixing can be 15°C, 25°C, 35°C, 45°C, 55°C, 65°C, 75°C, 85°C, 95°C or any value between 15°C and 95°C, and the time can be 0.5h, 0.8h, 1.2h, 1.8h, 2.2h, 2.8h, 3.2h, 3.8h, 4.2h, 4.8h, 5h or any value between 0.5h and 5h.

[0036] In some optional embodiments, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. the nanofiltration includes multi-stage nanofiltration; It should be noted that for multi-stage nanofiltration, the number of nanofiltration stages can be controlled by the sodium-to-lithium ratio in the nanofiltration clear liquid. The sodium-to-lithium ratio in the nanofiltration clear liquid can be controlled to be lower than 2 to determine the final number of nanofiltration stages.

[0037] B. The sodium ion concentration in the nanofiltration clear solution is 0.5 g / L-1 g / L; Optionally, the sodium ion concentration in the nanofiltration clear solution may be 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L or any value between 0.5 g / L and 1 g / L; C. The temperature of the nanofiltration is 5°C-50°C; Exemplarily, the temperature of nanofiltration can be 5°C, 8°C, 12°C, 18°C, 22°C, 28°C, 32°C, 38°C, 42°C, 48°C, 50°C or any value between 5°C and 50°C; D. The filtration pressure of the nanofiltration is 2Mpa-5Mpa; Exemplarily, the filtration pressure of nanofiltration can be 2 MPa, 2.2 MPa, 2.8 MPa, 3.2 MPa, 3.8 MPa, 4.2 MPa, 4.8 MPa, 5 MPa or any value between 2 MPa and 5 MPa; E. The pH of the nanofiltration clear liquid is 6-7.

[0038] Optionally, the pH of the nanofiltration supernatant can be 6, 6.5, 7 or any value between 6-7.

[0039] In some optional embodiments, the multi-stage nanofiltration includes three-stage nanofiltration; It should be noted that when the multi-stage nanofiltration is three-stage nanofiltration, the sodium-lithium mass ratio in the low-lithium solution is already lower than 2, and the lithium concentration in the solution reaches above 0.5 g / L, which is easy for subsequent reverse osmosis concentration. The lithium and sodium concentrations in the lithium-rich solution after reverse osmosis concentration are at the same order of magnitude, and impurity ions such as calcium in the solution can be removed by sodium carbonate to obtain a pure lithium-rich solution.

[0040] The three-stage nanofiltration comprises: the conditioned liquid is subjected to a first nanofiltration to obtain a first nanofiltration clear liquid and a first nanofiltration concentrated liquid; The first nanofiltration concentrate is subjected to MVR treatment to obtain sulfate; It should be noted that MVR treatment refers to mechanical vapor recompression technology. The first nanofiltration concentrate is subjected to MVR treatment to obtain sulfate. MVR evaporation crystallization technology has high efficiency and low energy consumption. The obtained sodium sulfate can be directly used as a roasting aid.

[0041] The first nanofiltration clear liquid is subjected to a second nanofiltration to obtain a second nanofiltration clear liquid and a second nanofiltration concentrate; The second nanofiltration clear liquid is subjected to a third nanofiltration to obtain a nanofiltration clear liquid and a nanofiltration concentrate; The second nanofiltration concentrate and the nanofiltration concentrate are returned to the upper stage for treatment in sequence; The sulfate is returned to the first mixing.

[0042] In some optional embodiments, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. the first reverse osmosis also obtains a first reverse osmosis clear liquid; The first reverse osmosis clear liquid is subjected to a second reverse osmosis to obtain a second reverse osmosis concentrated liquid and a second reverse osmosis clear liquid; The second reverse osmosis concentrate is returned to an upper stage for treatment; The second reverse osmosis clear liquid is returned for the water immersion; B. The lithium ion concentration in the first reverse osmosis concentrate is 5 g / L-10 g / L.

[0043] Optionally, the lithium ion concentration in the first reverse osmosis concentrate may be 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L or any value between 5 g / L and 10 g / L.

[0044] In some optional embodiments, the method for extracting lithium carbonate from clay-type lithium resources satisfies at least one of the following conditions: A. The temperature of the first reverse osmosis and the second reverse osmosis are independently 5°C-50°C; Exemplarily, the temperature of the first reverse osmosis and the second reverse osmosis can be independently 5°C, 8°C, 12°C, 18°C, 22°C, 28°C, 32°C, 38°C, 42°C, 48°C, 50°C or any value between 5°C and 50°C; B. The filtration pressures of the first reverse osmosis and the second reverse osmosis are independent of each other and are 6Mpa-10Mpa; Exemplarily, the filtration pressure of the first reverse osmosis and the second reverse osmosis can be 6 MPa, 6.5 MPa, 7.5 MPa, 8.5 MPa, 9.5 MPa, 10 MPa or any value between 6 MPa and 10 MPa, respectively, independently; C. The pH of the first reverse osmosis and the second reverse osmosis are independently 6-7.

[0045] Optionally, the pH of the first reverse osmosis and the second reverse osmosis can be independently 6, 6.5, 7 or any value between 6 and 7.

[0046] In some optional embodiments, the molar amount of the sodium carbonate is 1.2 to 1.5 times the molar amount of the lithium ions in the solution after impurity removal.

[0047] Optionally, the molar amount of sodium carbonate may be 1.2 times, 1.3 times, 1.4 times, 1.5 times or any value between 1.2 times and 1.5 times the molar amount of lithium ions in the solution after impurities are removed.

[0048] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0049] Example 1 This embodiment provides a method for extracting lithium carbonate from clay-type lithium resources, comprising: S1: Take 2000g of clay-type lithium resource powder, add 1000g of anhydrous sodium sulfate, mix and calcine at a temperature of 800°C for 2h to obtain a calcined material; S2: The roasted material is leached in water to obtain a slurry, the solid-liquid ratio of the leaching is 1g:15mL, the leaching temperature is 90°C, and the leaching time is 1h; S3: The pH value of the slurry is adjusted to 6-7 by 30% NaOH, and then calcium chloride in an amount equal to the molar amount of lithium ions in the slurry is added for conditioning treatment. After solid-liquid separation, a conditioned liquid and leached residue are obtained, and the pH value of the conditioned liquid is between 6-7; S4: The conditioned liquid is treated by three-stage nanofiltration membranes. During the nanofiltration process, the temperature of the solution is 30°C, the pH value is between 6-7, and the filtration pressure of the nanofiltration membrane is 3Mpa; The three-stage nanofiltration is specifically as follows: the conditioned liquid is subjected to a first-stage nanofiltration treatment to obtain a first-stage nanofiltration concentrate and a first-stage nanofiltration clear liquid (a first-stage lithium-containing solution); the first-stage nanofiltration concentrate is subjected to an MVR treatment to crystallize to obtain sodium sulfate, and the sodium sulfate can be returned for roasting as a roasting aid; the first-stage nanofiltration clear liquid is subjected to a second-stage nanofiltration treatment to obtain a second-stage nanofiltration concentrate and a second-stage nanofiltration clear liquid (a second-stage lithium-containing solution); the second-stage nanofiltration concentrate is returned to the upper stage for a first-stage nanofiltration treatment; the second-stage nanofiltration clear liquid is subjected to a third-stage nanofiltration treatment to obtain a third-stage nanofiltration concentrate and a third-stage nanofiltration clear liquid (a third-stage lithium-containing solution); the third-stage nanofiltration concentrate is returned to the upper stage for a second-stage nanofiltration treatment; S5: The tertiary nanofiltration clear liquid is treated by the primary reverse osmosis to obtain the primary reverse osmosis concentrate (lithium-rich solution) and the primary reverse osmosis clear liquid, the primary reverse osmosis clear liquid is treated by the secondary reverse osmosis to obtain the secondary reverse osmosis concentrate and the secondary reverse osmosis clear liquid, the secondary reverse osmosis concentrate is returned to the primary reverse osmosis treatment, and the secondary reverse osmosis clear liquid is returned for water immersion; the solution temperature during the primary reverse osmosis and secondary reverse osmosis processes is 30°C, the pH is between 6 and 7, and the reverse osmosis inlet pressure is 7.5Mpa; S6: The pH value of the primary reverse osmosis concentrate is adjusted to 13 by sodium hydroxide, and then a saturated sodium carbonate solution with a molar amount of 1.2 times that of calcium in the lithium-rich solution is added to remove impurities to obtain a decontaminated solution, and a saturated sodium carbonate solution is added to the decontaminated solution to react and obtain lithium carbonate.

[0050] The method for extracting lithium carbonate from clay-type lithium resources provided in this embodiment is as follows: Figure 1 shown.

[0051] Example 2 This embodiment provides a method for extracting lithium carbonate from clay-type lithium resources, comprising: S1: Take 2000g of clay-type lithium resource powder, add 800g of anhydrous sodium sulfate, mix and calcine at a temperature of 800°C for 2h to obtain a calcined material; S2: The roasted material is leached in water to obtain a slurry, the solid-liquid ratio of the leaching is 1g:15mL, the leaching temperature is 90°C, and the leaching time is 1h; S3: The pH value of the slurry is adjusted to 6-7 by 30% NaOH, and then calcium chloride in an amount equal to the molar amount of lithium ions in the slurry is added for conditioning treatment. After solid-liquid separation, a conditioned liquid and leached residue are obtained, and the pH value of the conditioned liquid is between 6-7; S4: The conditioned liquid is treated by three-stage nanofiltration membranes (consistent with Example 1). During the nanofiltration process, the temperature of the solution is 30° C., the pH value is between 6 and 7, and the filtration pressure of the nanofiltration membrane is 3 MPa; S5: The tertiary nanofiltration clear liquid is treated by the primary reverse osmosis to obtain the primary reverse osmosis concentrate (lithium-rich solution) and the primary reverse osmosis clear liquid, the primary reverse osmosis clear liquid is treated by the secondary reverse osmosis to obtain the secondary reverse osmosis concentrate and the secondary reverse osmosis clear liquid, the secondary reverse osmosis concentrate is returned to the primary reverse osmosis treatment, and the secondary reverse osmosis clear liquid is returned for water immersion; the solution temperature during the primary reverse osmosis and secondary reverse osmosis processes is 30°C, the pH is between 6 and 7, and the reverse osmosis inlet pressure is 7.5Mpa; S6: The primary reverse osmosis concentrate is subjected to impurity removal-precipitation treatment to obtain an impurity-removed solution, and a saturated sodium carbonate solution is added to the impurity-removed solution to react and obtain lithium carbonate.

[0052] Example 3 This embodiment provides a method for extracting lithium carbonate from clay-type lithium resources, comprising: S1: Take 2000g of clay-type lithium resource powder, add 600g of anhydrous sodium sulfate, mix and calcine at a temperature of 800°C for 2h to obtain a calcined material; S2: The roasted material is leached in water to obtain a slurry, the solid-liquid ratio of the leaching is 1g:15mL, the leaching temperature is 90°C, and the leaching time is 1h; S3: The pH value of the slurry is adjusted to 6-7 by 30% NaOH, and then calcium chloride in an amount equal to the molar amount of lithium ions in the slurry is added for conditioning treatment. After solid-liquid separation, a conditioned liquid and leached residue are obtained, and the pH value of the conditioned liquid is between 6-7; S4: The conditioned liquid is treated by three-stage nanofiltration membranes (consistent with Example 1). During the nanofiltration process, the temperature of the solution is 30° C., the pH value is between 6 and 7, and the filtration pressure of the nanofiltration membrane is 3 MPa; S5: The tertiary nanofiltration clear liquid is treated by the primary reverse osmosis to obtain the primary reverse osmosis concentrate (lithium-rich solution) and the primary reverse osmosis clear liquid, the primary reverse osmosis clear liquid is treated by the secondary reverse osmosis to obtain the secondary reverse osmosis concentrate and the secondary reverse osmosis clear liquid, the secondary reverse osmosis concentrate is returned to the primary reverse osmosis treatment, and the secondary reverse osmosis clear liquid is returned for water immersion; the solution temperature during the primary reverse osmosis and secondary reverse osmosis processes is 30°C, the pH is between 6 and 7, and the reverse osmosis inlet pressure is 7.5Mpa; S6: The primary reverse osmosis concentrate is subjected to impurity removal-precipitation treatment to obtain an impurity-removed solution, and a saturated sodium carbonate solution is added to the impurity-removed solution to react and obtain lithium carbonate.

[0053] Example 4 This embodiment provides a method for extracting lithium carbonate from clay-type lithium resources, comprising: S1: Take 2000g of clay-type lithium resource powder, add 1000g of anhydrous sodium sulfate, mix and calcine at a temperature of 700°C for 2h to obtain a calcined material; S2: The roasted material is leached in water to obtain a slurry, the solid-liquid ratio of the leaching is 1g:15mL, the leaching temperature is 90°C, and the leaching time is 1h; S3: The pH value of the slurry is adjusted to 6-7 by 30% NaOH, and then calcium chloride in an amount equal to the molar amount of lithium ions in the slurry is added for conditioning treatment. After solid-liquid separation, a conditioned liquid and leached residue are obtained, and the pH value of the conditioned liquid is between 6-7; S4: The conditioned liquid is treated by three-stage nanofiltration membranes (consistent with Example 1). During the nanofiltration process, the temperature of the solution is 30° C., the pH value is between 6 and 7, and the filtration pressure of the nanofiltration membrane is 3 MPa; S5: The tertiary nanofiltration clear liquid is treated by the primary reverse osmosis to obtain the primary reverse osmosis concentrate (lithium-rich solution) and the primary reverse osmosis clear liquid, the primary reverse osmosis clear liquid is treated by the secondary reverse osmosis to obtain the secondary reverse osmosis concentrate and the secondary reverse osmosis clear liquid, the secondary reverse osmosis concentrate is returned to the primary reverse osmosis treatment, and the secondary reverse osmosis clear liquid is returned for water immersion; the solution temperature during the primary reverse osmosis and secondary reverse osmosis processes is 30°C, the pH is between 6 and 7, and the reverse osmosis inlet pressure is 7.5Mpa; S6: The primary reverse osmosis concentrate is subjected to impurity removal-precipitation treatment to obtain an impurity-removed solution, and a saturated sodium carbonate solution is added to the impurity-removed solution to react and obtain lithium carbonate.

[0054] Example 5 This embodiment provides a method for extracting lithium carbonate from clay-type lithium resources, comprising: S1: Take 2000g of clay-type lithium resource powder, add 1000g of anhydrous sodium sulfate, mix and calcine at 900°C for 2h to obtain a calcined material; S2: The roasted material is leached in water to obtain a slurry, the solid-liquid ratio of the leaching is 1g:15mL, the leaching temperature is 90°C, and the leaching time is 1h; S3: The pH value of the slurry is adjusted to 6-7 by 30% NaOH, and then calcium chloride in an amount equal to the molar amount of lithium ions in the slurry is added for conditioning treatment. After solid-liquid separation, a conditioned liquid and leached residue are obtained, and the pH value of the conditioned liquid is between 6-7; S4: The conditioned liquid is treated by three-stage nanofiltration membranes (consistent with Example 1). During the nanofiltration process, the temperature of the solution is 30° C., the pH value is between 6 and 7, and the filtration pressure of the nanofiltration membrane is 3 MPa; S5: The tertiary nanofiltration clear liquid is treated by the primary reverse osmosis to obtain the primary reverse osmosis concentrate (lithium-rich solution) and the primary reverse osmosis clear liquid, the primary reverse osmosis clear liquid is treated by the secondary reverse osmosis to obtain the secondary reverse osmosis concentrate and the secondary reverse osmosis clear liquid, the secondary reverse osmosis concentrate is returned to the primary reverse osmosis treatment, and the secondary reverse osmosis clear liquid is returned for water immersion; the solution temperature during the primary reverse osmosis and secondary reverse osmosis processes is 30°C, the pH is between 6 and 7, and the reverse osmosis inlet pressure is 7.5Mpa; S6: The primary reverse osmosis concentrate is subjected to impurity removal-precipitation treatment to obtain an impurity-removed solution, and a saturated sodium carbonate solution is added to the impurity-removed solution to react and obtain lithium carbonate.

[0055] Comparative Example 1 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 1 in that the ore pulp of this comparative example is not treated with calcium chloride, and other conditions are consistent with Example 1.

[0056] Comparative Example 2 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 1 in that the ore pulp in this comparative example is tempered with sodium chloride, and other conditions are consistent with Example 1.

[0057] Comparative Example 3 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 1 in that the number of nanofiltration stages in this comparative example is two, and other conditions are consistent with Example 1.

[0058] Comparative Example 4 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 1 in that the nanofiltration level of this comparative example is one, and other conditions are consistent with Example 1.

[0059] Comparative Example 5 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 1 in that reverse osmosis is not performed in this comparative example, and other conditions are consistent with Example 1.

[0060] Comparative Example 6 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 1 in that nanofiltration is not performed in this comparative example, and other conditions are consistent with Example 1.

[0061] The lithium recovery rate / lithium concentration during nanofiltration and primary reverse osmosis were tested for the above Examples 1-5 and Comparative Examples 1-6. Specific data can be found in Table 1.

[0062] Table 1 Data test

[0063] Comparative Example 7 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 1 in that sodium sulfate is not added to the ore pulp of this comparative example, and other conditions are consistent with Example 1.

[0064] Comparative Example 8 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 1 in that the ore slurry in this comparative example replaces sodium sulfate with calcium sulfate, and other conditions are consistent with Example 1.

[0065] The lithium recovery rate / lithium concentration during nanofiltration and primary reverse osmosis were tested for Comparative Examples 7 and 8. The specific data can be seen in Table 2.

[0066] Table 2 Data test

[0067] From the above tests, it can be seen that Examples 1-5 prove that the lithium ion concentration in the primary reverse osmosis concentrate prepared according to the method provided in the present application can reach above 5 g / L.

[0068] Comparative Examples 1-2 prove that when the leached slurry is not tempered by calcium chloride or sodium chloride, the lithium content in the primary reverse osmosis concentrate is low, the sodium content is high, and the lithium-sodium separation effect is poor.

[0069] Comparative Examples 3-6 demonstrate that when the leaching solution does not undergo nanofiltration, has a low nanofiltration level, or does not pass through a reverse osmosis membrane, the lithium concentration in the primary reverse osmosis concentrate is low, less than 3.5 g / L, and the lithium concentration effect is poor.

[0070] Comparative Examples 7-8 prove that when roasting without an additive or roasting with a calcium sulfate additive, the lithium leaching rate is low, less than 45%, proving that it is difficult to extract lithium from the clay mineral by roasting without an additive-water leaching, and the calcium sulfate additive is difficult to completely destroy the structure of the clay mineral at this temperature, ultimately resulting in a low lithium leaching rate. Calcium sulfate is a slightly soluble substance and subsequently enters the slag, resulting in a large increase in the leached slag. Sodium sulfate has a large solubility, is cheap and easy to obtain, can be recycled, and has a low additive cost.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0072] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for extracting lithium carbonate from clay-type lithium resources, characterized in that: include: The clay-type lithium resource and sodium sulfate are first mixed and roasted to obtain a roasted material; The roasted material is subjected to water immersion to obtain a first slurry; The first ore pulp and sodium hydroxide are mixed for a second time to obtain a second ore pulp; The second ore slurry and calcium chloride are subjected to a third mixing and solid-liquid separation to obtain a conditioned liquid; The conditioned liquid is subjected to nanofiltration to obtain a nanofiltration clear liquid; The nanofiltration clear liquid is subjected to a first reverse osmosis to obtain a first reverse osmosis concentrate; The first reverse osmosis concentrated solution is subjected to impurity removal to obtain an impurity-removed solution; The impurity-removed solution and the saturated sodium carbonate solution are mixed for the fourth time to obtain lithium carbonate.

2. The method for extracting lithium carbonate from clay-type lithium resources according to claim 1, characterized in that: At least one of the following conditions is met: A. The mass of the sodium sulfate is 10%-100% of the mass of the clay-type lithium resource; B. The calcination temperature is 400°C-950°C, and the calcination time is 0.5h-5h.

3. The method for extracting lithium carbonate from clay-type lithium resources according to claim 2, characterized in that: The calcination temperature is 600° C.-900° C., and the calcination time is 1 h-3 h.

4. The method for extracting lithium carbonate from clay-type lithium resources according to claim 1, characterized in that: At least one of the following conditions is met: A. The water immersion temperature is 15°C-95°C, and the time is 0.5h-5h; B. The solid-liquid ratio of the water immersion is 1g:(5mL-30mL).

5. The method for extracting lithium carbonate from clay-type lithium resources according to claim 1, characterized in that: At least one of the following conditions is met: A. The pH value of the second slurry is 6-7; B. the molar amount of the calcium chloride is 0.8 to 1.2 times the molar amount of the lithium ions in the second slurry; C. The temperature of the third mixing is 15°C-95°C, and the time is 0.5h-5h.

6. The method for extracting lithium carbonate from clay-type lithium resources according to claim 1, characterized in that: At least one of the following conditions is met: A. the nanofiltration includes multi-stage nanofiltration; B. The sodium ion concentration in the nanofiltration clear solution is 0.5 g / L-1.5 g / L; C. The temperature of the nanofiltration is 5°C-50°C; D. The filtration pressure of the nanofiltration is 2Mpa-5Mpa; E. The pH of the nanofiltration clear liquid is 6-7.

7. The method for extracting lithium carbonate from clay-type lithium resources according to claim 6, characterized in that: The multi-stage nanofiltration includes three-stage nanofiltration; The three-stage nanofiltration comprises: the conditioned liquid is subjected to a first nanofiltration to obtain a first nanofiltration clear liquid and a first nanofiltration concentrated liquid; The first nanofiltration concentrate is subjected to MVR treatment to obtain sulfate; The first nanofiltration clear liquid is subjected to a second nanofiltration to obtain a second nanofiltration clear liquid and a second nanofiltration concentrate; The second nanofiltration clear liquid is subjected to a third nanofiltration to obtain a nanofiltration clear liquid and a nanofiltration concentrate; The second nanofiltration concentrate and the nanofiltration concentrate are returned to the upper stage for treatment in sequence; The sulfate is returned to the first mixing.

8. The method for extracting lithium carbonate from clay-type lithium resources according to claim 1, characterized in that: At least one of the following conditions is met: A. the first reverse osmosis also obtains a first reverse osmosis clear liquid; The first reverse osmosis clear liquid is subjected to a second reverse osmosis to obtain a second reverse osmosis concentrated liquid and a second reverse osmosis clear liquid; The second reverse osmosis concentrate is returned to an upper stage for treatment; The second reverse osmosis clear liquid is returned for the water immersion; B. The lithium ion concentration in the first reverse osmosis concentrate is 5 g / L-10 g / L.

9. The method for extracting lithium carbonate from clay-type lithium resources according to claim 8, characterized in that: At least one of the following conditions is met: A. The temperature of the first reverse osmosis and the second reverse osmosis are independently 5°C-50°C; B. The filtration pressure of the first reverse osmosis and the second reverse osmosis are independently 6Mpa-10Mpa; C. The pH of the first reverse osmosis and the second reverse osmosis are independently 6-7.

10. The method for extracting lithium carbonate from clay-type lithium resources according to any one of claims 1 to 9, characterized in that: The molar amount of the sodium carbonate is 1.2 to 1.5 times the molar amount of the lithium ions in the solution after impurities are removed.

Images