A method for leaching lithium from lithium ore using inorganic-organic mixed acid

Abstract

The present invention relates to a method for leaching lithium from lithium ore using an inorganic-organic mixed acid. A method for leaching lithium from lithium ore using an inorganic-organic mixed acid comprises the following steps: roasting lithium-containing ore powder and cooling; adding an inorganic acid solution to the roasted lithium-containing ore powder to obtain a mixed solution, adjusting the pH value of the mixed solution to below 2, stirring under a first preset temperature, adding a solid organic acid, and then stirring under a second preset temperature to obtain an acid-ore mixture, wherein the second preset temperature is greater than the first preset temperature; leaching the acid-ore mixture at a temperature of 30 to 150°C, separating the solid and the liquid, and obtaining a lithium-containing solution. The present invention solves the problems of the existing use of strong acids to extract lithium from lithium ore, which have high acid consumption, difficulty in subsequent treatment, and the generated strong acidic waste liquid that pollutes the environment.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium extraction, and in particular to a method for leaching lithium from lithium ore by using inorganic-organic mixed acid. Background Art

[0002] Lithium metal and its compounds are core raw materials for lithium-ion batteries. Currently, the most mined lithium resources are lithium-rich ores found in salt lake brines and lithium-bearing ores, which have high lithium contents. However, lithium-poor resources, such as clay ores, generally have low lithium contents and immature extraction technologies. Therefore, developing processes for extracting lithium from clay ores is of great significance.

[0003] Leaching lithium from ore or concentrate is a critical step in the lithium extraction process. Since most lithium resides within the ore's crystal structure, it must be disrupted to extract it. Therefore, current methods for leaching lithium from ore typically use highly concentrated strong acids such as sulfuric acid, nitric acid, and nicotinic acid. This results in high acid consumption, makes subsequent treatment difficult, and produces highly acidic wastewater, which significantly pollutes the environment. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for leaching lithium from lithium ore using an inorganic-organic mixed acid, so as to solve the problems of the existing method of extracting lithium from lithium ore using a strong acid, such as high acid consumption, difficulty in subsequent treatment and serious environmental pollution caused by the generated strong acidic waste liquid.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] 1. A method for leaching lithium from lithium ore using an inorganic-organic mixed acid, comprising the following steps:

[0007] S1, roasting the lithium-containing ore powder and cooling;

[0008] S2. Adding a low-concentration inorganic acid solution to the calcined lithium-containing ore powder to obtain a mixed solution, adjusting the pH value of the mixed solution to below 2, stirring the mixed solution under a first preset temperature, adding a solid organic acid, and further stirring the mixed solution under a second preset temperature to obtain an acid-ore mixture, wherein the second preset temperature is greater than the first preset temperature;

[0009] S3, the acid ore mixture at temperature

[0010] Leaching is carried out at a temperature of 30 to 150° C., and solid-liquid separation is performed to obtain a lithium-containing solution.

[0011] According to the above technical means, by sequentially calcining to activate the powder, the calcination can make the mineral loose and porous, effectively increasing the contact area of ​​the reaction, thereby improving the lithium leaching rate. Then, an inorganic acid is added and stirred at a certain temperature to fully adjust the pH of the environment in which the lithium-containing mineral powder is located and to have a certain effect on the mineral structure, causing the mineral structure to further relax, so that the subsequently added organic acid can fully exert its complex coordination effect. Then, an organic acid is added and stirred at a certain temperature, so that the organic acid and the lithium in the lithium-containing mineral powder are complexed and coordinated, effectively improving the leaching efficiency of lithium ions.

[0012] Preferably, in S1, the calcination temperature is 300° C. to 600° C., and the calcination time is 3 min to 30 min.

[0013] By adopting the short-time roasting method, not only the lithium ion leaching rate is guaranteed, but also the energy consumption is effectively reduced.

[0014] Preferably, in S2, the solid-to-liquid ratio of the lithium-containing ore powder to the inorganic acid solution is 1:1 to 1:10 g / L.

[0015] Preferably, in S2, the molar concentration of the inorganic acid solution is 0.1 mol / L to 2 mol / L.

[0016] By using low-concentration inorganic acid to adjust the pH value of lithium-containing ore powder, the usage and concentration of inorganic acid are effectively reduced.

[0017] Preferably, in S2, the mass ratio of solid organic acid to lithium-containing mineral powder is 1:1 to 1:10.

[0018] Preferably, in S3, the leaching reaction time is 6 hours to 24 hours.

[0019] Preferably, in S2, the first preset temperature is 20°C to 50°C, and the stirring time under the first preset temperature condition is 0.5 to 3 hours.

[0020] By controlling the temperature between 20°C and 50°C for stirring, not only is the environment of the solution adjusted to an acidic environment, thereby destroying the hydrogen bonds between the unit layers of the mineral, but the lower first preset temperature also achieves an energy-saving effect while adjusting the pH; at the same time, the stirring time under the first preset temperature is controlled to be 0.5 to 3 hours, thereby enhancing the effect of low-concentration inorganic acid on the mineral powder and causing the mineral to be initially relaxed.

[0021] Preferably, in S2, the second preset temperature is 80°C to 120°C.

[0022] By increasing the second preset temperature, the added organic acid can be fully dissolved.

[0023] Preferably, in S2, the inorganic acid is selected from at least one of sulfuric acid, nitric acid and phosphoric acid;

[0024] The organic acid is selected from at least one of citric acid, oxalic acid, malic acid, ethylenediaminetetraacetic acid and tartaric acid.

[0025] Preferably, in said S1, before roasting, the step further comprises: ball milling the lithium ore to obtain lithium-containing ore powder having a mesh size of less than or equal to 180 meshes;

[0026] The lithium ore is clay-type lithium ore or concentrate.

[0027] Beneficial effects of the present invention:

[0028] The present invention discloses a method for leaching lithium from lithium ore using an inorganic-organic mixed acid. By selecting a relatively low concentration of inorganic acid in combination with an organic acid as the leaching medium for lithium ore, the inorganic acid adjusts the acidity while the organic acid provides coordination to leach the lithium. Compared to using only organic acid, the inorganic-organic mixed acid system uses a low concentration of inorganic acid, which not only reduces the corrosion to equipment and environmental pollution caused by high-concentration inorganic acid, but also exposes more contactable surfaces between each layer due to the weak binding force of hydrogen bonds, which are easily broken in an acidic environment. In this case, a small amount of organic acid is used, which can fully coordinate and complex with the lithium ions in the exposed contact surfaces. Compared to using only organic acid, the inorganic-organic mixed acid system significantly reduces the amount of organic acid used, reduces leaching costs, and is more suitable for industrial applications. The invention has promotional and application value in the field of lithium extraction technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the XRD test result diagram of clay rock type lithium ore;

[0030] Figure 2 The present invention is a flow chart of a method for leaching lithium from lithium ore using an inorganic-organic mixed acid. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art will readily appreciate the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the various details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are intended only to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0032] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0033] Claystone lithium ore or concentrate is a clay-type ore with very low lithium content. The XRD analysis results of claystone lithium ore are as follows: Figure 1 As shown. Figure 1 Analysis shows that the main phases of the sample are: lithium chlorite, quartz, calcite, illite, pyrite, and dolomite. The XRF analysis results of the clay-type associated lithium ore containing lithium chlorite are shown in Table 1. From the analysis in Table 1, it can be seen that quartz accounts for 50.532%, and the aluminum oxide and calcium oxide contents are relatively high, at 27.068% and 14.135% respectively; the lithium content is 3061ug / g, which is a low-lithium ore, and other metal oxides account for a relatively low proportion. The trace element analysis of the clay-type associated lithium ore containing lithium chlorite is shown in Table 2. From the analysis in Table 2, it can be seen that the lithium content in the clay-type associated lithium ore containing lithium chlorite is 3061ug / g. The clay-type associated lithium ores in the following examples are all clay-type associated lithium ore containing lithium chlorite.

[0034] Table 1 XRF results of clay-type associated lithium ore containing lithium chlorite

[0035]

[0036] Table 2 Trace element analysis (ug / g)

[0037]

[0038] Example 1

[0039] like Figure 2 As shown, a method for leaching lithium from lithium ore using an inorganic-organic mixed acid comprises the following steps:

[0040] S1, crushing, ball milling and screening the clay rock type lithium ore, taking clay rock type lithium ore powder less than or equal to 200 mesh for standby use;

[0041] S2. calcining the lithium-containing ore powder obtained in S1 at 500°C for 10 minutes, and then cooling to room temperature;

[0042] S3, the lithium-containing ore powder obtained by cooling in S2 is mixed with a sulfuric acid solution with a molar mass of 0.3 mol / L at a solid-liquid ratio of 1:4 g / L to obtain a mixed solution with a pH value less than 2, and the solution is stirred at 35° C. for 3 h, and then oxalic acid is added at a mass ratio of oxalic acid to ore powder of 1:5, and the mixture is stirred at 85° C. to obtain an acid-ore mixture;

[0043] S4. Leaching the acid ore mixture obtained in S3 at a temperature of 85° C. for 12 hours, and performing solid-liquid separation to obtain a lithium-containing solution.

[0044] Example 2

[0045] like Figure 2 As shown, a method for leaching lithium from lithium ore using an inorganic-organic mixed acid comprises the following steps:

[0046] S1, crushing, ball milling and screening the clay rock type lithium ore, taking clay rock type lithium ore powder less than or equal to 180 mesh for standby;

[0047] S2. calcining the lithium-containing ore powder obtained in S1 at 450°C for 15 minutes, and then cooling to room temperature;

[0048] S3, the lithium-containing ore powder obtained by cooling in S2 is mixed with a sulfuric acid solution with a molar mass of 0.2 mol / L at a solid-liquid ratio of 1:5 g / L to obtain a mixed solution with a pH value less than 2, and the solution is stirred at 35° C. for 3 h, and then oxalic acid is added at a mass ratio of oxalic acid to ore powder of 1:3, and the mixture is stirred at 85° C. to obtain an acid-ore mixture;

[0049] S4. Leaching the acid ore mixture obtained in S3 at a temperature of 85° C. for 6 hours, and performing solid-liquid separation to obtain a lithium-containing solution.

[0050] Example 3

[0051] like Figure 2 As shown, a method for leaching lithium from lithium ore using an inorganic-organic mixed acid comprises the following steps:

[0052] S1, crushing, ball milling and screening the clay rock type lithium ore, taking clay rock type lithium ore powder less than or equal to 180 mesh for standby;

[0053] S2. calcining the lithium-containing ore powder obtained in S1 at 550°C for 5 minutes, and then cooling to room temperature;

[0054] S3, the lithium-containing ore powder obtained by cooling in S2 is mixed with a nitric acid solution with a molar mass of 0.2 mol / L at a solid-liquid ratio of 1:4 g / L to obtain a mixed solution with a pH value less than 2, and the solution is stirred at 35° C. for 3 h, and then oxalic acid is added at a mass ratio of oxalic acid to ore powder of 1:3, and the mixture is stirred at 95° C. to obtain an acid-ore mixture;

[0055] S4. Leaching the acid ore mixture obtained in S3 at a temperature of 85° C. for 6 hours, and performing solid-liquid separation to obtain a lithium-containing solution.

[0056] Example 4

[0057] like Figure 2 As shown, a method for leaching lithium from lithium ore using an inorganic-organic mixed acid comprises the following steps:

[0058] S1, crushing, ball milling and screening the clay rock type lithium ore, taking clay rock type lithium ore powder less than or equal to 200 mesh for standby;

[0059] S2. calcining the lithium-containing ore powder obtained in S1 at 500°C for 10 minutes, and then cooling to room temperature;

[0060] S3, the lithium-containing ore powder obtained by cooling in S2 is mixed with a nitric acid solution with a molar mass of 0.5 mol / L at a solid-liquid ratio of 1:3 g / L to obtain a mixed solution with a pH <2, and stirred at 35°C for 3 hours, and then citric acid is added at a mass ratio of citric acid to ore powder of 1:1, and the mixture is stirred at 90°C to obtain an acid-ore mixture;

[0061] S4. Leaching the acid ore mixture obtained in S3 at a temperature of 90° C. for 6 hours, and performing solid-liquid separation to obtain a lithium-containing solution.

[0062] Example 5

[0063] like Figure 2 As shown, a method for leaching lithium from lithium ore using an inorganic-organic mixed acid comprises the following steps:

[0064] S1, crushing, ball milling and screening the clay rock type lithium ore, taking clay rock type lithium ore powder less than or equal to 200 mesh for standby use;

[0065] S2. calcining the lithium-containing ore powder obtained in S1 at 500°C for 5 minutes, and then cooling to room temperature;

[0066] S3, the lithium-containing ore powder obtained by cooling in S2 is mixed with a sulfuric acid solution with a molar mass of 0.5 mol / L at a solid-liquid ratio of 1:4 g / L to obtain a mixed solution with a pH value less than 2, and the mixture is stirred at 30° C. for 3 h, and then ethylenediaminetetraacetic acid is added, with the mass ratio of ethylenediaminetetraacetic acid to ore powder being 1:10, and the mixture is stirred at 80° C. to obtain an acid ore mixture;

[0067] S4. Leaching the acid ore mixture obtained in S3 at a temperature of 90° C. for 6 hours, and performing solid-liquid separation to obtain a lithium-containing solution.

[0068] Example 6

[0069] like Figure 2 As shown, a method for leaching lithium from lithium ore using an inorganic-organic mixed acid comprises the following steps:

[0070] S1, crushing, ball milling and screening the clay rock type lithium ore, taking clay rock type lithium ore powder less than or equal to 200 mesh for standby use;

[0071] S2. calcining the lithium-containing ore powder obtained in S1 at 500°C for 8 minutes, and then cooling to room temperature;

[0072] S3, the lithium-containing ore powder obtained by cooling in S2 is mixed with a sulfuric acid solution with a molar mass of 1.0 mol / L at a solid-liquid ratio of 1:5 g / L to obtain a mixed solution with a pH value less than 2, and the solution is stirred at 40° C. for 3 h, and then citric acid is added at a mass ratio of citric acid to ore powder of 1:3, and the mixture is stirred at 90° C. to obtain an acid-ore mixture;

[0073] S4. Leaching the acid-ore mixture obtained in S3 at 80° C. for 24 hours, and performing solid-liquid separation to obtain a lithium-containing solution.

[0074] Detection and Analysis

[0075] 1) Lithium leaching rate detection

[0076] The lithium-containing filtrates obtained in Examples 1 to 6 were placed in volumetric flasks for constant volume, and then the lithium-containing filtrates after constant volume were diluted to appropriate multiples for atomic absorption testing. The lithium leaching rates obtained in Examples 1 to 6 were 90.13%, 93.56%, 92.33%, 93.09%, 95.46% and 88.74%, respectively.

[0077] 2) Detection of lithium content in lithium-containing filtrate

[0078] The filter residues obtained in Examples 1 to 6 were subjected to ICP testing to infer the lithium content in the lithium-containing filtrate. The lithium content obtained from Examples 1 to 6 is shown in Table 3:

[0079] Table 3 Lithium content obtained in Examples 1 to 6 (mg / g)

[0080]

[0081] 3) Detection of various contents in lithium-containing filtrate

[0082] The lithium-containing filtrates obtained in Examples 1 to 6 were subjected to ICP full element analysis, and the results are shown in Table 4 (only major elements are listed).

[0083] Table 4 ICP results (mg / L) of lithium-containing filtrates obtained in Examples 1 to 6

[0084]

[0085] 4) Filter residue detection

[0086] The filter residues obtained in Examples 1 to 6 were subjected to XRF analysis, and the results are shown in Table 5 below.

[0087] Table 5 XRF results of filter residues obtained in Examples 1 to 6

[0088]

[0089]

[0090]

[0091] In summary, the present invention uses an inorganic-organic mixed acid to leach lithium from lithium ore. By selecting a relatively low concentration of inorganic acid in combination with an organic acid as the leaching medium for lithium ore, the inorganic acid adjusts the acidity and the organic acid provides coordination to leach lithium. Compared with using only organic acid, the inorganic-organic mixed acid system uses a low concentration of inorganic acid, which not only reduces the corrosion of equipment and environmental pollution caused by high concentrations of inorganic acid, but also the unit layers in the mineral are connected by hydrogen bonds. Since the binding force of hydrogen bonds is weak, they are easily destroyed in an acidic environment, exposing more contactable surfaces between each layer. At this time, a small amount of organic acid is used, and this part of the organic acid can fully produce coordination and complexation with the lithium ions in the exposed contact surface. Compared with using only organic acid, under the condition of achieving the same lithium leaching rate, the inorganic-organic mixed acid system greatly reduces the amount of organic acid used, reduces the leaching cost, and is more suitable for industrial application. In the field of lithium extraction technology, it has promotion and application value.

[0092] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A method for leaching lithium from lithium ore using an inorganic-organic mixed acid, characterized in that: The following steps are involved: S1, roasting the lithium-containing ore powder and cooling; S2. Adding an inorganic acid solution to the calcined lithium-containing ore powder to obtain a mixed solution, adjusting the pH value of the mixed solution to below 2, stirring the mixed solution under a first preset temperature, adding a solid organic acid, and further stirring the mixed solution under a second preset temperature to obtain an acid-ore mixture, wherein the second preset temperature is greater than the first preset temperature; S3, leaching the acid ore mixture at a temperature of 80-150° C., separating the solid and the liquid to obtain a lithium-containing solution; According to the above technical means, by sequentially adopting roasting, adding inorganic acid and stirring at a certain temperature to fully adjust the pH of the environment in which the lithium-containing ore powder is located, and then adding organic acid and stirring at a certain temperature, the organic acid is complexed with the lithium in the lithium-containing ore powder, thereby effectively improving the leaching efficiency of lithium ions; The first preset temperature is 20°C to 50°C, and the stirring time under the first preset temperature condition is 0.5 to 3 hours; The second preset temperature is 80℃~120℃; The lithium ore is clay-type lithium ore or concentrate; The organic acid is selected from ethylenediaminetetraacetic acid.

2. The method for leaching lithium from lithium ore using an inorganic-organic mixed acid according to claim 1, characterized in that: In the step S1, the calcination temperature is 300° C. to 900° C., and the calcination time is 3 min to 30 min.

3. The method for leaching lithium from lithium ore using an inorganic-organic mixed acid according to claim 1, characterized in that: In the S2, the solid-liquid ratio of the lithium-containing ore powder to the inorganic acid solution is 1:1~1:10 g / L.

4. The method for leaching lithium from lithium ore using an inorganic-organic mixed acid according to claim 1, characterized in that: In the S2, the molar concentration of the inorganic acid solution is 0.1 mol / L to 2 mol / L.

5. The method for leaching lithium from lithium ore using an inorganic-organic mixed acid according to claim 1, characterized in that: In S2, the mass ratio of the solid organic acid to the lithium-containing mineral powder is 1:1 to 1:

10.

6. The method for leaching lithium from lithium ore using an inorganic-organic mixed acid according to claim 1, characterized in that: In S3, the leaching reaction time is 6 hours to 24 hours.

7. The method for leaching lithium from lithium ore using an inorganic-organic mixed acid according to claim 1, characterized in that: In the S2, the inorganic acid is selected from at least one of sulfuric acid, nitric acid and phosphoric acid.

8. The method for leaching lithium from lithium ore using an inorganic-organic mixed acid according to claim 1, characterized in that: In the above S1, before roasting, the process further includes: ball milling the lithium ore to obtain lithium-containing ore powder with a mesh size of less than or equal to 180 meshes.

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