Method for selectively extracting lithium carbonate from clay type lithium ore

Abstract

The invention provides a method for selectively extracting lithium carbonate from clay type lithium ore, and relates to the technical field of lithium extraction. The method for selectively extracting the lithium carbonate from the clay type lithium ore comprises the following steps: carrying out first mixing on the clay type lithium ore and calcium chloride, and roasting to obtain a roasted material; the roasted material and water are subjected to second mixing, leaching and solid-liquid separation, and a leaching solution and leaching residues are obtained; carrying out nanofiltration on the leachate to obtain a low-lithium solution and a nanofiltration concentrated solution; performing first reverse osmosis on the low-lithium solution to obtain a lithium-rich solution and a first reverse osmosis clear solution; the lithium-rich solution is subjected to impurity removal, and an impurity-removed solution is obtained; and carrying out third mixing on the impurity-removed solution and a saturated sodium carbonate solution to obtain lithium carbonate. The efficient extraction of lithium in the clay type lithium ore can be selectively realized by using calcium chloride as an auxiliary agent, the separation of calcium and lithium can be realized without consuming other reagents in the whole separation process, the reagent cost is low, no wastewater is discharged, and the environmental protection effect is good.

Description

Technical Field

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

[0002] The lithium in clay-type lithium ores (kaolinite, montmorillonite, illite, etc.) does not form a separate mineral phase, which makes it difficult to enrich through conventional mineral processing. The lithium is mainly present in clay minerals in the form of surface adsorption, interlayers, pores, within the lattice, and lattice substitution. As a result, the aluminum oxide octahedron structure needs to be destroyed before lithium is extracted, thereby releasing the lithium in the lattice and interlayers to make the lithium extractable.

[0003] Due to the low grade of lithium in clay-type lithium ore and the high content of acid-consuming elements such as aluminum, the conventional acid leaching process causes a large amount of aluminum leaching, making subsequent aluminum-lithium separation difficult; water leaching after calcination of the additive can inhibit the leaching of some aluminum, but since the concentration of lithium in the leachate is low and the concentration of soluble additives is high, a large amount of auxiliary reagents must be added to achieve the separation of lithium from other cations, and the reagent consumption is large. Summary of the invention

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

[0005] To achieve the above objectives, the present application provides a method for selectively extracting lithium carbonate from clay-type lithium ore, comprising: The clay-type lithium ore and calcium chloride are first mixed and roasted to obtain a roasted material; The roasted material and water are subjected to a second mixing, leaching, and solid-liquid separation to obtain a leachate and a leach residue; The leachate is subjected to nanofiltration to obtain a low-lithium solution and a nanofiltration concentrate; The low-lithium solution is subjected to a first reverse osmosis to obtain a lithium-rich solution and a first reverse osmosis clear solution; The lithium-rich solution is subjected to impurity removal to obtain an impurity-removed solution; The impurity-removed liquid and the saturated sodium carbonate solution are mixed for the third time to obtain lithium carbonate.

[0006] Optionally, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The mass of the calcium chloride is 10%-100% of the mass of the clay-type lithium ore; B. The amount of the saturated sodium carbonate solution is 1.2 to 1.5 times the molar amount of lithium in the impurity-removed liquid.

[0007] Optionally, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The calcination temperature is 450°C-950°C and the calcination time is 0.5h-5h; B. The leaching temperature is 15°C-95°C and the leaching time is 0.5-5h; C. The solid-liquid ratio of the leaching is 1g: (5mL-30mL).

[0008] Optionally, the calcination temperature is 600°C-900°C, and the calcination time is 1h-3h.

[0009] Optionally, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The filtration pressure of the nanofiltration is 2Mpa-5Mpa; B. The nanofiltration comprises: The leachate is subjected to a first nanofiltration to obtain a first lithium-containing solution and a first nanofiltration concentrate; The first lithium-containing solution is subjected to a second nanofiltration to obtain a second lithium-containing solution and a second nanofiltration concentrate; The second lithium-containing solution is subjected to a third nanofiltration to obtain a low-lithium solution and a nanofiltration concentrate.

[0010] Optionally, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. subjecting the first nanofiltration concentrate to MVR treatment to obtain a crystallized material; The crystallized material is returned to the first mixing; B. the second nanofiltration concentrate is returned to the first nanofiltration; C. The nanofiltration concentrate is returned for the second nanofiltration.

[0011] Optionally, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. subjecting the first reverse osmosis clear liquid to a second reverse osmosis to obtain a second reverse osmosis clear liquid and a reverse osmosis concentrated liquid; The reverse osmosis concentrate is returned to the first reverse osmosis; The second reverse osmosis clear liquid is returned for the leaching; B. The pressure of the first reverse osmosis is 6Mpa-10Mpa.

[0012] Optionally, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The filtration pressure of the second reverse osmosis is 6Mpa-10Mpa; B. The temperature of the second reverse osmosis is 5°C-50°C; C. The pH of the second reverse osmosis is 3-7.

[0013] Optionally, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The temperature of the nanofiltration and the first reverse osmosis are independently 5°C-50°C; B. The pH of the nanofiltration and the first reverse osmosis are independently 3-7.

[0014] Optionally, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The lithium ion concentration in the low lithium solution is 0.5 g / L-1 g / L; B. The lithium ion concentration in the lithium-rich solution is 5g / L-10g / L.

[0015] Compared with the prior art, the beneficial effects of this application include: The present application provides a method for selectively extracting lithium carbonate from clay-type lithium ore. Calcium chloride is used as an auxiliary agent. During the roasting process, calcium ions react with silicon in clay minerals to form substances such as calcium silicate, destroying the kaolinite structure in the clay minerals. Lithium forms lithium chloride, and other elements do not react with calcium chloride. Therefore, lithium chloride in the product can be selectively roasted by water leaching, and a single calcium chloride auxiliary agent avoids the complication of the components of the subsequent leaching solution system. The main ions in the leachate are lithium and calcium, and the hydrated ion radii of the two are quite different. Nanofiltration can be used to achieve efficient separation of lithium and calcium, and the separated low-lithium solution can be enriched with lithium through a reverse osmosis process. The entire separation process does not consume other reagents to achieve the separation of calcium and lithium, the reagent cost is low, and there is no wastewater discharge, and the environmental protection effect is good. 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 A schematic flow chart of the method for selectively extracting lithium carbonate from clay-type lithium ore provided in Example 1. DETAILED DESCRIPTION

[0018] As used herein: "Prepared from" is synonymous with "comprising".

[0019] The conjunction "consisting of" excludes any elements, steps or components not stated.

[0020] When a numerical range is described herein, unless otherwise indicated, that range is intended to include the endpoints and all integers and fractions within that range.

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

[0022] “Parts by mass” refers to the basic measurement unit that indicates the mass ratio of multiple components. One part can represent any unit mass, such as 1 g or 2.689 g.

[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 provides a method for selectively extracting lithium carbonate from clay-type lithium ore, comprising: The clay-type lithium ore and calcium chloride are first mixed and roasted to obtain a roasted material; The roasted material and water are subjected to a second mixing, leaching, and solid-liquid separation to obtain a leachate and a leach residue; The leachate is subjected to nanofiltration to obtain a low-lithium solution and a nanofiltration concentrate; The low-lithium solution is subjected to a first reverse osmosis to obtain a lithium-rich solution and a first reverse osmosis clear solution; The lithium-rich solution is subjected to impurity removal to obtain an impurity-removed solution; The impurity-removed liquid and sodium carbonate are mixed for the third time to obtain lithium carbonate.

[0025] In some embodiments, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The mass of the calcium chloride is 10%-100% of the mass of the clay-type lithium ore; Optionally, the mass of calcium chloride can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% or any value between 10% and 100% of the mass of the clay-type lithium ore; It should be noted that when the mass of calcium chloride is 10%-100% of the mass of clay-type lithium ore, when it is lower than 10%, most of the clay mineral structure has not dissociated, resulting in a low lithium extraction rate. When the calcium chloride content exceeds 100%, the calcium concentration in the water extract is high, causing greater pressure in the subsequent nanofiltration process and reducing the service life of the nanofiltration membrane.

[0026] B. The amount of the saturated sodium carbonate solution is 1.2 to 1.5 times the molar amount of lithium in the impurity-removed liquid.

[0027] Optionally, the amount of the saturated sodium carbonate solution can 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 in the liquid after impurities are removed.

[0028] In some embodiments, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The calcination temperature is 450°C-950°C and the calcination time is 0.5h-5h; Optionally, the calcination temperature may be 450°C, 500°C, 600°C, 700°C, 800°C, 900°C, 950°C or any value between 450°C and 950°C, and the calcination time may be 0.5h, 1h, 2h, 3h, 4h, 5h or any value between 0.5h and 5h; B. The leaching temperature is 15°C-95°C and the leaching time is 0.5-5h; Optionally, the leaching temperature may be 15°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 95°C or any value between 15°C and 95°C, and the leaching time may be 0.5h, 1h, 2h, 3h, 4h, 5h or any value between 0.5h and 5h; C. The solid-liquid ratio of the leaching is 1g: (5mL-30mL).

[0029] Optionally, the solid-liquid ratio of the leaching can be 1g:5mL, 1g:10mL, 1g:15mL, 1g:20mL, 1g:25mL, 1g:30mL or any value between 1g:(5mL-30mL).

[0030] In some embodiments, the calcination temperature is 600° C.-900° C., and the calcination time is 1 h-3 h.

[0031] Optionally, the calcination temperature may be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C or any value between 600°C and 900°C, and the calcination time may be 1h, 2h, 3h or any value between 1h and 3h.

[0032] It should be noted that when the calcination temperature is 600℃-900℃ and the time is 1h-3h, too low temperature and too short time will make it difficult for silicon and calcium to react completely, while too high temperature and too long time will lead to high energy consumption in the calcination process, thereby increasing costs.

[0033] In some embodiments, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The filtration pressure of the nanofiltration is 2Mpa-5Mpa; Optionally, the filtration pressure of the nanofiltration can be 2Mpa, 3Mpa, 4Mpa, 5Mpa or any value between 2Mpa and 5Mpa; It should be noted that when the filtration pressure of nanofiltration is 2Mpa-5Mpa, if the filtration pressure is too low, the lithium-calcium separation efficiency will be reduced, and the number of stages will need to be increased subsequently to increase the lithium-calcium separation efficiency. If the filtration pressure is too high, it will burden the equipment and reduce the service life of the nanofiltration membrane.

[0034] B. The nanofiltration comprises: The leachate is subjected to a first nanofiltration to obtain a first lithium-containing solution and a first nanofiltration concentrate; The first lithium-containing solution is subjected to a second nanofiltration to obtain a second lithium-containing solution and a second nanofiltration concentrate; The second lithium-containing solution is subjected to a third nanofiltration to obtain a low-lithium solution and a nanofiltration concentrate.

[0035] It should be noted that after the third stage of nanofiltration, the calcium-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 calcium concentrations in the lithium-rich solution after reverse osmosis concentration are at the same order of magnitude, and the calcium ions in the solution can be removed by sodium carbonate to obtain a pure lithium-rich solution.

[0036] In some embodiments, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. subjecting the first nanofiltration concentrate to MVR treatment to obtain a crystallized material; The crystallized material is returned to the first mixing; It should be noted that MVR refers to mechanical vapor recompression technology. The first nanofiltration concentrate is subjected to MVR treatment. MVR evaporation crystallization technology has high efficiency and low energy consumption. The obtained calcium chloride can be directly used as a roasting aid.

[0037] B. the second nanofiltration concentrate is returned to the first nanofiltration; C. The nanofiltration concentrate is returned for the second nanofiltration.

[0038] In some embodiments, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. subjecting the first reverse osmosis clear liquid to a second reverse osmosis to obtain a second reverse osmosis clear liquid and a reverse osmosis concentrated liquid; The reverse osmosis concentrate is returned to the first reverse osmosis; The second reverse osmosis clear liquid is returned for the leaching; It should be noted that the lithium concentration in the lithium-rich solution after the first-level reverse osmosis has reached more than 5g / L. The first-level reverse osmosis clear liquid is subjected to secondary reverse osmosis treatment to further recover a small amount of lithium in the first-level reverse osmosis clear liquid, thereby improving the comprehensive recovery rate of lithium.

[0039] B. The pressure of the first reverse osmosis is 6Mpa-10Mpa.

[0040] Optionally, the pressure of the first reverse osmosis can be 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa or any value between 6 MPa and 10 MPa.

[0041] In some embodiments, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The filtration pressure of the second reverse osmosis is 6Mpa-10Mpa; Optionally, the pressure of the second reverse osmosis can be 6Mpa, 7Mpa, 8Mpa, 9Mpa, 10Mpa or any value between 6Mpa and 10Mpa; B. The temperature of the second reverse osmosis is 5°C-50°C; Optionally, the temperature of the second reverse osmosis can be 5°C, 10°C, 15°C, 20°C, 30°C, 40°C, 50°C or any value between 5°C and 50°C; C. The pH of the second reverse osmosis is 3-7.

[0042] Optionally, the pH of the second reverse osmosis can be 3, 4, 5, 6, 7 or any value between 3-7.

[0043] In some embodiments, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The temperature of the nanofiltration and the first reverse osmosis are independently 5°C-50°C; Optionally, the temperature of the nanofiltration and the first reverse osmosis can be independently 5°C, 10°C, 15°C, 20°C, 30°C, 40°C, 50°C or any value between 5°C and 50°C; B. The pH of the nanofiltration and the first reverse osmosis are independently 3-7.

[0044] Optionally, the pH of the nanofiltration and the first reverse osmosis can be independently 3, 4, 5, 6, 7 or any value between 3 and 7.

[0045] It should be noted that the pH of the nanofiltration and the first reverse osmosis is controlled between 3-7, which reduces the corrosion of the solution to the nanofiltration membrane and the reverse osmosis membrane and can increase the service life of the membrane.

[0046] In some embodiments, the method for selectively extracting lithium carbonate from clay-type lithium ore satisfies at least one of the following conditions: A. The lithium ion concentration in the low lithium solution is 0.5 g / L-1 g / L; Optionally, the lithium ion concentration in the low lithium 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; B. The lithium ion concentration in the lithium-rich solution is 5g / L-10g / L.

[0047] Optionally, the lithium ion concentration in the lithium-rich solution 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.

[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 selectively extracting lithium carbonate from clay-type lithium ore, comprising: 2000 g of clay-type lithium resource powder was mixed with 600 g of anhydrous calcium chloride, and chlorination roasted to obtain a roasted material at a roasting temperature of 850° C. for 2 h. The roasted material was leached in water, the solid-liquid ratio was 1g:15mL, the leaching temperature was 90°C, the time was 1h, and the leaching liquid and leaching residue were obtained after solid-liquid separation; The leachate is sequentially subjected to primary nanofiltration, secondary nanofiltration, and tertiary nanofiltration. The leachate is subjected to primary nanofiltration to obtain a primary nanofiltration concentrate and a primary lithium-containing solution. The primary nanofiltration concentrate is subjected to MVR treatment, and is concentrated and crystallized to obtain chloride (calcium chloride). The chloride is returned to the roasting process for reuse. The primary lithium-containing solution is subjected to secondary nanofiltration to obtain a secondary lithium-containing solution and a secondary nanofiltration concentrate. The secondary nanofiltration concentrate is returned to the first nanofiltration process for reuse. The secondary lithium-containing solution is subjected to tertiary nanofiltration to obtain a tertiary lithium-containing solution (low-lithium solution) and a tertiary nanofiltration concentrate. The tertiary nanofiltration concentrate is returned to the second nanofiltration process for reuse. During the nanofiltration process, the pH value of the leachate is between 5 and 7, the temperature of the leachate is 30° C., and the filtration pressure of the tertiary nanofiltration membrane is 3Mpa. The tertiary lithium-containing solution is subjected to primary reverse osmosis treatment by a reverse osmosis processor to obtain a lithium-rich solution and a primary reverse osmosis clear solution. The primary reverse osmosis clear solution is subjected to secondary reverse osmosis treatment to obtain a secondary reverse osmosis clear solution (water) and a secondary reverse osmosis concentrated solution. The secondary reverse osmosis clear solution is returned for water immersion, and the secondary reverse osmosis concentrated solution is returned to the primary reverse osmosis for reuse. The inlet pressure of the reverse osmosis processor is 7.5Mpa. The pH value of the solution during the reverse osmosis process is between 5-7, and the temperature is 30°C. The pH value of the lithium-rich solution is adjusted to 13 by sodium hydroxide, and then a saturated sodium carbonate solution of 1.2 times the molar amount of calcium in the lithium-rich solution is added to remove impurities. After the impurities are removed, a saturated sodium carbonate solution is added to obtain lithium carbonate.

[0050] The specific process of the method for selectively extracting lithium carbonate from clay-type lithium ore is as follows: Figure 1 shown.

[0051] Example 2 This embodiment provides a method for selectively extracting lithium carbonate from clay-type lithium ore, comprising: 2000 g of clay-type lithium resource powder was mixed with 800 g of anhydrous calcium chloride, and chlorination roasted to obtain a roasted material at a roasting temperature of 850° C. for 2 h. The roasted material was leached in water, the solid-liquid ratio was 1g:15mL, the leaching temperature was 90°C, the time was 1h, and the leaching liquid and leaching residue were obtained after solid-liquid separation; The leachate is sequentially subjected to primary nanofiltration, secondary nanofiltration, and tertiary nanofiltration. The leachate is subjected to primary nanofiltration to obtain a primary nanofiltration concentrate and a primary lithium-containing solution. The primary nanofiltration concentrate is subjected to MVR treatment, and is concentrated and crystallized to obtain chloride (calcium chloride). The chloride is returned to the roasting process for reuse. The primary lithium-containing solution is subjected to secondary nanofiltration to obtain a secondary lithium-containing solution and a secondary nanofiltration concentrate. The secondary nanofiltration concentrate is returned to the first nanofiltration process for reuse. The secondary lithium-containing solution is subjected to tertiary nanofiltration to obtain a tertiary lithium-containing solution (low-lithium solution) and a tertiary nanofiltration concentrate. The tertiary nanofiltration concentrate is returned to the second nanofiltration process for reuse. During the nanofiltration process, the pH value of the leachate is between 5 and 7, the temperature of the leachate is 30° C., and the filtration pressure of the tertiary nanofiltration membrane is 3Mpa. The tertiary lithium-containing solution is subjected to primary reverse osmosis treatment by a reverse osmosis processor to obtain a lithium-rich solution and a primary reverse osmosis clear solution. The primary reverse osmosis clear solution is subjected to secondary reverse osmosis treatment to obtain a secondary reverse osmosis clear solution (water) and a secondary reverse osmosis concentrated solution. The secondary reverse osmosis clear solution is returned for water immersion, and the secondary reverse osmosis concentrated solution is returned to the primary reverse osmosis for reuse. The inlet pressure of the reverse osmosis processor is 7.5Mpa. The pH value of the solution during the reverse osmosis process is between 5-7, and the temperature is 30°C. The lithium-rich solution is subjected to impurity removal and precipitation, and then a saturated sodium carbonate solution is added to obtain lithium carbonate.

[0052] Example 3 This embodiment provides a method for selectively extracting lithium carbonate from clay-type lithium ore, comprising: 2000 g of clay-type lithium resource powder was mixed with 600 g of anhydrous calcium chloride, and chlorination roasted to obtain a roasted material at a roasting temperature of 800° C. for 2 h. The roasted material was leached in water, the solid-liquid ratio was 1g:15mL, the leaching temperature was 90°C, the time was 1h, and the leaching liquid and leaching residue were obtained after solid-liquid separation; The leachate is sequentially subjected to primary nanofiltration, secondary nanofiltration, and tertiary nanofiltration. The leachate is subjected to primary nanofiltration to obtain a primary nanofiltration concentrate and a primary lithium-containing solution. The primary nanofiltration concentrate is subjected to MVR treatment, and is concentrated and crystallized to obtain chloride (calcium chloride). The chloride is returned to the roasting process for reuse. The primary lithium-containing solution is subjected to secondary nanofiltration to obtain a secondary lithium-containing solution and a secondary nanofiltration concentrate. The secondary nanofiltration concentrate is returned to the first nanofiltration process for reuse. The secondary lithium-containing solution is subjected to tertiary nanofiltration to obtain a tertiary lithium-containing solution (low-lithium solution) and a tertiary nanofiltration concentrate. The tertiary nanofiltration concentrate is returned to the second nanofiltration process for reuse. During the nanofiltration process, the pH value of the leachate is between 5 and 7, the temperature of the leachate is 30° C., and the filtration pressure of the tertiary nanofiltration membrane is 3Mpa. The tertiary lithium-containing solution is subjected to primary reverse osmosis treatment by a reverse osmosis processor to obtain a lithium-rich solution and a primary reverse osmosis clear solution. The primary reverse osmosis clear solution is subjected to secondary reverse osmosis treatment to obtain a secondary reverse osmosis clear solution (water) and a secondary reverse osmosis concentrated solution. The secondary reverse osmosis clear solution is returned for water immersion, and the secondary reverse osmosis concentrated solution is returned to the primary reverse osmosis for reuse. The inlet pressure of the reverse osmosis processor is 7.5Mpa. The pH value of the solution during the reverse osmosis process is between 5-7, and the temperature is 30°C. The lithium-rich solution is subjected to impurity removal and precipitation, and then a saturated sodium carbonate solution is added to obtain lithium carbonate.

[0053] Example 4 This embodiment provides a method for selectively extracting lithium carbonate from clay-type lithium ore, comprising: 2000 g of clay-type lithium resource powder was mixed with 600 g of anhydrous calcium chloride, and chlorination roasted to obtain a roasted material at a roasting temperature of 600° C. for 2 h. The roasted material was leached in water, the solid-liquid ratio was 1g:15mL, the leaching temperature was 90°C, the time was 1h, and the leaching liquid and leaching residue were obtained after solid-liquid separation; The leachate is sequentially subjected to primary nanofiltration, secondary nanofiltration, and tertiary nanofiltration. The leachate is subjected to primary nanofiltration to obtain a primary nanofiltration concentrate and a primary lithium-containing solution. The primary nanofiltration concentrate is subjected to MVR treatment, and is concentrated and crystallized to obtain chloride (calcium chloride). The chloride is returned to the roasting process for reuse. The primary lithium-containing solution is subjected to secondary nanofiltration to obtain a secondary lithium-containing solution and a secondary nanofiltration concentrate. The secondary nanofiltration concentrate is returned to the first nanofiltration process for reuse. The secondary lithium-containing solution is subjected to tertiary nanofiltration to obtain a tertiary lithium-containing solution (low-lithium solution) and a tertiary nanofiltration concentrate. The tertiary nanofiltration concentrate is returned to the second nanofiltration process for reuse. During the nanofiltration process, the pH value of the leachate is between 5 and 7, the temperature of the leachate is 30° C., and the filtration pressure of the tertiary nanofiltration membrane is 3Mpa. The tertiary lithium-containing solution is subjected to primary reverse osmosis treatment by a reverse osmosis processor to obtain a lithium-rich solution and a primary reverse osmosis clear solution. The primary reverse osmosis clear solution is subjected to secondary reverse osmosis treatment to obtain a secondary reverse osmosis clear solution (water) and a secondary reverse osmosis concentrated solution. The secondary reverse osmosis clear solution is returned for water immersion, and the secondary reverse osmosis concentrated solution is returned to the primary reverse osmosis for reuse. The inlet pressure of the reverse osmosis processor is 7.5Mpa. The pH value of the solution during the reverse osmosis process is between 5-7, and the temperature is 30°C. The lithium-rich solution is subjected to impurity removal and precipitation, and then a saturated sodium carbonate solution is added to obtain lithium carbonate.

[0054] Example 5 This embodiment provides a method for selectively extracting lithium carbonate from clay-type lithium ore, comprising: 2000 g of clay-type lithium resource powder was mixed with 400 g of anhydrous calcium chloride, and chlorination roasted to obtain a roasted material at a roasting temperature of 850° C. for 2 h. The roasted material was leached in water, the solid-liquid ratio was 1g:15mL, the leaching temperature was 90°C, the time was 1h, and the leaching liquid and leaching residue were obtained after solid-liquid separation; The leachate is sequentially subjected to primary nanofiltration, secondary nanofiltration, and tertiary nanofiltration. The leachate is subjected to primary nanofiltration to obtain a primary nanofiltration concentrate and a primary lithium-containing solution. The primary nanofiltration concentrate is subjected to MVR treatment, and is concentrated and crystallized to obtain chloride (calcium chloride). The chloride is returned to the roasting process for reuse. The primary lithium-containing solution is subjected to secondary nanofiltration to obtain a secondary lithium-containing solution and a secondary nanofiltration concentrate. The secondary nanofiltration concentrate is returned to the first nanofiltration process for reuse. The secondary lithium-containing solution is subjected to tertiary nanofiltration to obtain a tertiary lithium-containing solution (low-lithium solution) and a tertiary nanofiltration concentrate. The tertiary nanofiltration concentrate is returned to the second nanofiltration process for reuse. During the nanofiltration process, the pH value of the leachate is between 5 and 7, the temperature of the leachate is 30° C., and the filtration pressure of the tertiary nanofiltration membrane is 3Mpa. The tertiary lithium-containing solution is subjected to primary reverse osmosis treatment by a reverse osmosis processor to obtain a lithium-rich solution and a primary reverse osmosis clear solution. The primary reverse osmosis clear solution is subjected to secondary reverse osmosis treatment to obtain a secondary reverse osmosis clear solution (water) and a secondary reverse osmosis concentrated solution. The secondary reverse osmosis clear solution is returned for water immersion, and the secondary reverse osmosis concentrated solution is returned to the primary reverse osmosis for reuse. The inlet pressure of the reverse osmosis processor is 7.5Mpa. The pH value of the solution during the reverse osmosis process is between 5-7, and the temperature is 30°C. The lithium-rich solution is subjected to impurity removal and precipitation, and then a saturated sodium carbonate solution is added to obtain lithium carbonate.

[0055] Example 6 This embodiment provides a method for selectively extracting lithium carbonate from clay-type lithium ore, comprising: 2000 g of clay-type lithium resource powder was mixed with 600 g of anhydrous calcium chloride, and chlorination roasted to obtain a roasted material at a roasting temperature of 900° C. for 2 h. The roasted material was leached in water, the solid-liquid ratio was 1g:15mL, the leaching temperature was 90°C, the time was 1h, and the leaching liquid and leaching residue were obtained after solid-liquid separation; The leachate is sequentially subjected to primary nanofiltration, secondary nanofiltration, and tertiary nanofiltration. The leachate is subjected to primary nanofiltration to obtain a primary nanofiltration concentrate and a primary lithium-containing solution. The primary nanofiltration concentrate is subjected to MVR treatment, and is concentrated and crystallized to obtain chloride (calcium chloride). The chloride is returned to the roasting process for reuse. The primary lithium-containing solution is subjected to secondary nanofiltration to obtain a secondary lithium-containing solution and a secondary nanofiltration concentrate. The secondary nanofiltration concentrate is returned to the first nanofiltration process for reuse. The secondary lithium-containing solution is subjected to tertiary nanofiltration to obtain a tertiary lithium-containing solution (low-lithium solution) and a tertiary nanofiltration concentrate. The tertiary nanofiltration concentrate is returned to the second nanofiltration process for reuse. During the nanofiltration process, the pH value of the leachate is between 5 and 7, the temperature of the leachate is 30° C., and the filtration pressure of the tertiary nanofiltration membrane is 3Mpa. The tertiary lithium-containing solution is subjected to primary reverse osmosis treatment by a reverse osmosis processor to obtain a lithium-rich solution and a primary reverse osmosis clear solution. The primary reverse osmosis clear solution is subjected to secondary reverse osmosis treatment to obtain a secondary reverse osmosis clear solution (water) and a secondary reverse osmosis concentrated solution. The secondary reverse osmosis clear solution is returned for water immersion, and the secondary reverse osmosis concentrated solution is returned to the primary reverse osmosis for reuse. The inlet pressure of the reverse osmosis processor is 7.5Mpa. The pH value of the solution during the reverse osmosis process is between 5-7, and the temperature is 30°C. The lithium-rich solution is subjected to impurity removal and precipitation, and then a saturated sodium carbonate solution is added to obtain lithium carbonate.

[0056] Example 7 This embodiment provides a method for selectively extracting lithium carbonate from clay-type lithium ore, comprising: 2000 g of clay-type lithium resource powder was mixed with 600 g of anhydrous calcium chloride, and chlorination roasted to obtain a roasted material at a roasting temperature of 850° C. for 2 h. The roasted material was leached in water, the solid-liquid ratio was 1g:10mL, the leaching temperature was 90°C, the time was 1h, and the leaching liquid and leaching residue were obtained after solid-liquid separation; The leachate is sequentially subjected to primary nanofiltration, secondary nanofiltration, and tertiary nanofiltration. The leachate is subjected to primary nanofiltration to obtain a primary nanofiltration concentrate and a primary lithium-containing solution. The primary nanofiltration concentrate is subjected to MVR treatment, and is concentrated and crystallized to obtain chloride (calcium chloride). The chloride is returned to the roasting process for reuse. The primary lithium-containing solution is subjected to secondary nanofiltration to obtain a secondary lithium-containing solution and a secondary nanofiltration concentrate. The secondary nanofiltration concentrate is returned to the first nanofiltration process for reuse. The secondary lithium-containing solution is subjected to tertiary nanofiltration to obtain a tertiary lithium-containing solution (low-lithium solution) and a tertiary nanofiltration concentrate. The tertiary nanofiltration concentrate is returned to the second nanofiltration process for reuse. During the nanofiltration process, the pH value of the leachate is between 5 and 7, the temperature of the leachate is 30° C., and the filtration pressure of the tertiary nanofiltration membrane is 3Mpa. The tertiary lithium-containing solution is subjected to primary reverse osmosis treatment by a reverse osmosis processor to obtain a lithium-rich solution and a primary reverse osmosis clear solution. The primary reverse osmosis clear solution is subjected to secondary reverse osmosis treatment to obtain a secondary reverse osmosis clear solution (water) and a secondary reverse osmosis concentrated solution. The secondary reverse osmosis clear solution is returned for water immersion, and the secondary reverse osmosis concentrated solution is returned to the primary reverse osmosis for reuse. The inlet pressure of the reverse osmosis processor is 7.5Mpa. The pH value of the solution during the reverse osmosis process is between 5-7, and the temperature is 30°C. The lithium-rich solution is subjected to impurity removal and precipitation, and then a saturated sodium carbonate solution is added to obtain lithium carbonate.

[0057] 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 number of nanofiltration stages in this comparative example is two, and other conditions are consistent with Example 1.

[0058] 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 nanofiltration level of this comparative example is one, and other conditions are consistent with Example 1.

[0059] Comparative Example 3 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 7 in that the nanofiltration level of this comparative example is one, and other conditions are consistent with Example 7.

[0060] Comparative Example 4 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 7 in that the roasting aid in this comparative example is anhydrous magnesium chloride, and other conditions are consistent with Example 1.

[0061] 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 the roasting aid in this comparative example is sodium chloride, and other conditions are consistent with Example 1.

[0062] Comparative Example 6 This comparative example provides a method for extracting lithium carbonate from clay-type lithium ore, which is different from Example 4 in that the roasting aid in this comparative example is anhydrous magnesium chloride, and other conditions are consistent with Example 4.

[0063] The products obtained from the above embodiments and comparative examples were tested for lithium leaching rate, lithium calcium magnesium sodium ion concentration in the leachate, primary nanofiltration, secondary nanofiltration, tertiary nanofiltration, and primary reverse osmosis concentrate.

[0064] The lithium recovery rate, the lithium concentration data in the low-lithium solution and the primary reverse osmosis concentrate are shown in Table 1.

[0065] Table 1 Lithium concentration data

[0066] It can be seen from Table 1 that the lithium leaching rate of Examples 1-7 reaches more than 85%, the lithium concentration in the leachate is more than 0.08 g / L, the calcium concentration is more than 7.2 g / L, the lithium concentration reaches more than 0.6 g / L after three-stage nanofiltration, and the lithium concentration reaches more than 6 g / L after one reverse osmosis.

[0067] Comparative Examples 1-2 demonstrate that when the nanofiltration stage is reduced to stage 1 and stage 2, the calcium concentration in the primary reverse osmosis concentrate reaches 16 g / L and 34 g / L or more, respectively, and the lithium-calcium separation effect is poor.

[0068] Comparative Example 3 demonstrates that when the nanofiltration stage is reduced, the calcium concentration in the primary reverse osmosis concentrate reaches above 52 g / L, resulting in poor lithium-calcium separation effect.

[0069] Comparative Examples 4-6 prove that when the roasting aids are magnesium chloride and sodium chloride, the lithium leaching rate is low, less than 35%, indicating that magnesium chloride and sodium chloride basically do not react with kaolinite minerals in clay minerals and cannot destroy the kaolinite mineral structure. Therefore, the lithium in the kaolinite mineral structure and interlayer cannot be fully released. Calcium chloride can destroy the kaolinite mineral structure and release lithium through ion substitution or other means. Subsequent simple water leaching can achieve the leaching of lithium chloride. Lithium and calcium can be separated by nanofiltration due to their large difference in hydrated ion radius. The low-lithium solution can subsequently be used to enrich and extract lithium by reverse osmosis. The process is simple, the consumption of external reagents is low, and there is no wastewater discharge.

[0070] 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.

[0071] 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 selectively extracting lithium carbonate from clay-type lithium ore, characterized in that: include: The clay-type lithium ore and calcium chloride are first mixed and roasted to obtain a roasted material; The roasted material and water are subjected to a second mixing, leaching, and solid-liquid separation to obtain a leachate and a leach residue; The leachate is subjected to nanofiltration to obtain a low-lithium solution and a nanofiltration concentrate; The low-lithium solution is subjected to a first reverse osmosis to obtain a lithium-rich solution and a first reverse osmosis clear solution; The lithium-rich solution is subjected to impurity removal to obtain an impurity-removed solution; The impurity-removed liquid and the saturated sodium carbonate solution are mixed for the third time to obtain lithium carbonate.

2. The method for selectively extracting lithium carbonate from clay-type lithium ore according to claim 1, characterized in that: At least one of the following conditions is met: A. The mass of the calcium chloride is 10%-100% of the mass of the clay-type lithium ore; B. The amount of the saturated sodium carbonate solution is 1.2 to 1.5 times the molar amount of lithium in the impurity-removed liquid.

3. The method for selectively extracting lithium carbonate from clay-type lithium ore according to claim 1, characterized in that: At least one of the following conditions is met: A. The calcination temperature is 450°C-950°C and the calcination time is 0.5h-5h; B. The leaching temperature is 15°C-95°C and the leaching time is 0.5-5h; C. The solid-liquid ratio of the leaching is 1g: (5mL-30mL).

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

5. The method for selectively extracting lithium carbonate from clay-type lithium ore according to claim 1, characterized in that: At least one of the following conditions is met: A. The filtration pressure of the nanofiltration is 2Mpa-5Mpa; B. The nanofiltration comprises: The leachate is subjected to a first nanofiltration to obtain a first lithium-containing solution and a first nanofiltration concentrate; The first lithium-containing solution is subjected to a second nanofiltration to obtain a second lithium-containing solution and a second nanofiltration concentrate; The second lithium-containing solution is subjected to a third nanofiltration to obtain a low-lithium solution and a nanofiltration concentrate.

6. The method for selectively extracting lithium carbonate from clay-type lithium ore according to claim 5, characterized in that: At least one of the following conditions is met: A. subjecting the first nanofiltration concentrate to MVR treatment to obtain a crystallized material; The crystallized material is returned to the first mixing; B. the second nanofiltration concentrate is returned to the first nanofiltration; C. The nanofiltration concentrate is returned for the second nanofiltration.

7. The method for selectively extracting lithium carbonate from clay-type lithium ore according to claim 1, characterized in that: At least one of the following conditions is met: A. subjecting the first reverse osmosis clear liquid to a second reverse osmosis to obtain a second reverse osmosis clear liquid and a reverse osmosis concentrated liquid; The reverse osmosis concentrate is returned to the first reverse osmosis; The second reverse osmosis clear liquid is returned for the leaching; B. The pressure of the first reverse osmosis is 6Mpa-10Mpa.

8. The method for selectively extracting lithium carbonate from clay-type lithium ore according to claim 7, characterized in that: At least one of the following conditions is met: A. The filtration pressure of the second reverse osmosis is 6Mpa-10Mpa; B. The temperature of the second reverse osmosis is 5°C-50°C; C. The pH of the second reverse osmosis is 3-7.

9. The method for selectively extracting lithium carbonate from clay-type lithium ore according to claim 1, characterized in that: At least one of the following conditions is met: A. The temperature of the nanofiltration and the first reverse osmosis are independently 5°C-50°C; B. The pH of the nanofiltration and the first reverse osmosis are independently 3-7.

10. The method for selectively extracting lithium carbonate from clay-type lithium ore according to any one of claims 1 to 9, characterized in that: At least one of the following conditions is met: A. The lithium ion concentration in the low lithium solution is 0.5 g / L-1 g / L; B. The lithium ion concentration in the lithium-rich solution is 5g / L-10g / L.

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