A roasting process for improving the lithium conversion in lepidolite

Abstract

The application provides a roasting process for improving lithium conversion rate in lepidolite, and the specific steps are as follows: wet grinding of lepidolite and citric acid solution to obtain lepidolite powder; dry ball milling of the lepidolite powder and tannic acid to obtain pretreated lepidolite powder; mixing of the pretreated lepidolite powder and concentrated sulfuric acid, drying, low-temperature roasting to obtain pre-roasted material; high-temperature roasting of the pre-roasted material to form clinker, cooling, grinding and preparing; water immersion of the ground clinker, filtration of the leaching solution, impurity removal and purification, lithium precipitation, drying and crushing to obtain lithium carbonate. The lepidolite and citric acid are wet ground to activate the surface activation energy, the dry ball milling of the lepidolite and tannic acid enlarges the interlayer spacing of the lepidolite, which is beneficial to mass transfer and diffusion of lithium during roasting, can activate lithium sites, improve the leaching rate of lithium, and can also fix impurities, reduce the wrapping of lithium and the impurities in the subsequent leaching solution, and the method is simple, cost reduction and efficiency improvement are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium mica lithium extraction, in particular to a roasting process for improving the lithium conversion rate in lithium mica. BACKGROUND

[0002] With the rapid development of global new energy industry, especially the urgent demand for lithium resources in the field of electric vehicles and energy storage, lithium mica as an important supplement to solid lithium resources has always been concerned about its lithium extraction technology. At present, the lithium extraction process of lithium mica is still in the development stage, and the existing lithium extraction process of lithium mica can be roughly divided into acid method, alkali method and salt method, such as limestone roasting method, sulfate roasting method, chlorination roasting method and sulfuric acid roasting method. However, there are the following shortcomings: high roasting temperature and high energy consumption; limited lithium conversion rate, difficult to remove impurities such as sulfate, high impurity content, the need for subsequent multi-stage purification, long process; a large amount of waste residue and wastewater will be produced, which will pollute the environment if not properly treated; it is difficult to recover other valuable metals, high cost and low resource utilization.

[0003] In fact, the purpose of lithium mica roasting is to destroy its original complex aggregate structure by high-temperature roasting, open the lithium mica flaky structure, and facilitate the physical and chemical changes of lithium in lithium mica and the beneficial substance element components added in the raw material formula, so as to convert the originally insoluble lithium into lithium compounds that are easy to dissolve. In the roasting process, the more sufficient the reaction between lithium and raw material components, the higher the lithium extraction rate.

[0004] Therefore, we need to find a process method aimed at improving the lithium conversion rate in lithium mica, while reducing energy consumption, not polluting the environment, and reducing the production cost of lithium carbonate. SUMMARY

[0005] In view of this, the present application provides a roasting process for improving the lithium conversion rate in lithium mica.

[0006] The technical scheme of the present application is as follows:

[0007] A roasting process for improving the lithium conversion rate in lithium mica, comprising the following steps:

[0008] S1, wet grinding lithium mica and citric acid solution to obtain lithium mica powder;

[0009] S2, dry ball milling the lithium mica powder of step S1 and tannic acid to obtain pretreated lithium mica powder;

[0010] S3, mixing the pretreated lithium mica powder of step S2 with concentrated sulfuric acid, drying, and roasting at 300-400℃ for 40-60min to obtain a pre-roasted material;

[0011] S4, roasting the pre-roasted material of step S3 at 600-700 DEG C for 1-2h to form clinker, and after cooling, grinding the clinker to form a powder for use;

[0012] S5, water immersion of the ground clinker of step S4, filtration of the leaching solution, impurity removal and purification, lithium precipitation, drying and crushing to obtain lithium carbonate.

[0013] Further, in step S1, the mass concentration of the citric acid solution is 30%-50%; the solid-liquid ratio of the lepidolite and the citric acid solution is 1:10-15g / mL.

[0014] Further, in step S1, the wet grinding time is 20-30min.

[0015] Further, in step S1, the mass ratio of the lepidolite powder and tannic acid is 1:0.3-0.5.

[0016] Further, in step S2, the dry ball milling time is 10-20min, and the ball-to-material ratio is 5-10:1.

[0017] Further, in step S3, the volume concentration of the concentrated sulfuric acid is 96%-98%; the mass ratio of the pretreated lepidolite powder and the concentrated sulfuric acid is 1:0.4-0.6.

[0018] Further, in step S3, the drying temperature is 100-150 DEG C, and the drying time is 15-30min.

[0019] Further, in step S4, the particle size of the ground powder is controlled to be 60-150 mesh.

[0020] Further, in step S5, the water immersion is carried out at 30-40 DEG C and 100-200rpm for 30-50min.

[0021] Compared with the prior art, the beneficial effects of the present application are:

[0022] The lithium mica and citric acid are wet ground, the surface activation energy of the lithium mica is activated, active sites are provided for subsequent processing, then dry ball milling is carried out with tannic acid, the tannic acid has a rich phenolic hydroxyl structure, the interlayer spacing of the lithium mica can be expanded through hydrogen bonding, mass transfer and diffusion of lithium during subsequent calcination are facilitated, lithium sites can be activated in a directional manner, bond energy is reduced, enrichment of lithium sites is realized, and the leaching rate of lithium is improved. The lithium mica subjected to wet grinding and dry ball milling in the pre-calcination stage can form a loose and porous structure, bulk diffusion of lithium during subsequent high-temperature calcination is facilitated, and the reconstruction of the silicon-aluminum phase to lithium is inhibited, finally, directional recrystallization of lithium is realized during high-temperature calcination, and the phenolic hydroxyl groups can also fix Al and Fe impurities, reduce the wrapping of lithium, reduce impurities in the subsequent leaching solution, the method is simple, the operation cost is reduced, the energy consumption is reduced, the environmental pressure is reduced, and the cost is reduced and the efficiency is improved. DETAILED DESCRIPTION

[0023] In order to better understand the technical content of the present application, specific examples are provided below to further illustrate the present application.

[0024] The experimental methods used in the embodiments of the present application are conventional methods unless otherwise specified.

[0025] The materials, reagents, etc. used in the embodiments of the present application can be obtained from commercial channels unless otherwise specified.

[0026] Example 1

[0027] A calcination process for improving the conversion rate of lithium in lithium mica, the specific steps include:

[0028] S1, wet grinding lithium mica and 40wt% citric acid solution according to the solid-liquid ratio of 1:13g / mL for 25min to obtain lithium mica powder;

[0029] S2, dry ball milling the lithium mica powder of step S1 and tannic acid according to the mass ratio of 1:0.4 for 15min, the ball-to-material ratio is 8:1, to obtain pretreated lithium mica powder;

[0030] S3, mixing the pretreated lithium mica powder of step S2 and 98%v / v concentrated sulfuric acid according to the mass ratio of 1:0.5, drying at 130℃ for 25min, then low-temperature calcination, specifically: calcining at 350℃ for 50min to obtain pre-calcined material;

[0031] S4, high-temperature calcination of the pre-calcined material of step S3, specifically: calcining at 650℃ for 1.5h to form clinker, the clinker is cooled and ground into powder with a particle size of 60 mesh for standby;

[0032] S5, the ground clinker of step S4 is water immersed, water immersed at 35℃, 150 rpm, leaching for 40 min, filtering the leaching solution, impurity removal and purification, lithium precipitation and drying and crushing to obtain lithium carbonate.

[0033] Example 2

[0034] A roasting process for improving the lithium conversion rate in lepidolite, the specific steps comprising:

[0035] S1, according to the ratio of solid to liquid 1:10 g / mL, wet grinding lepidolite and 30wt% citric acid solution for 20 min to obtain lepidolite powder;

[0036] S2, according to the mass ratio 1:0.3, dry ball milling the lepidolite powder of step S1 and tannic acid for 10 min, the ball to material ratio is 5:1, to obtain pretreated lepidolite powder;

[0037] S3, mixing the pretreated lepidolite powder of step S2 with 98% v / v concentrated sulfuric acid in a mass ratio of 1:0.4, drying at 100℃ for 15 min, and then low-temperature roasting, specifically: roasting at 300℃ for 40 min to obtain pre-roasted material;

[0038] S4, high-temperature roasting the pre-roasted material of step S3, specifically: roasting at 600℃ for 1h to form clinker, after cooling the clinker, grinding the clinker to control the particle size at 60 mesh, ready for use;

[0039] S5, the ground clinker of step S4 is water immersed, water immersed at 30℃, 100 rpm, leaching for 30 min, filtering the leaching solution, impurity removal and purification, lithium precipitation and drying and crushing to obtain lithium carbonate.

[0040] Example 3

[0041] A roasting process for improving the lithium conversion rate in lepidolite, the specific steps comprising:

[0042] S1, according to the ratio of solid to liquid 1:15 g / mL, wet grinding lepidolite and 50wt% citric acid solution for 30 min to obtain lepidolite powder;

[0043] S2, according to the mass ratio 1:0.5, dry ball milling the lepidolite powder of step S1 and tannic acid for 20 min, the ball to material ratio is 10:1, to obtain pretreated lepidolite powder;

[0044] S3, mixing the pretreated lepidolite powder of step S2 with 98% v / v concentrated sulfuric acid in a mass ratio of 1:0.6, drying at 150℃ for 30 min, and then low-temperature roasting, specifically: roasting at 400℃ for 60 min to obtain pre-roasted material;

[0045] S4, high-temperature roasting the pre-roasted material of step S3, specifically: roasting at 700℃ for 2h, forming clinker, after the clinker is cooled, grinding the clinker into powder, the particle size is controlled at 150 mesh, ready for use;

[0046] S5, water immersion of the ground clinker of step S4, water immersion at 40℃, 200rpm, leaching for 50min, filtering the leaching solution, impurity removal and purification, lithium precipitation, drying and crushing, to obtain lithium carbonate.

[0047] Example 4

[0048] A roasting process for improving the conversion rate of lithium in lepidolite, the specific steps include:

[0049] S1, wet grinding lithium mica and 50wt% citric acid solution according to the ratio of 1:10g / mL, to obtain lithium mica powder;

[0050] S2, dry ball milling the lithium mica powder of step S1 and tannic acid according to the ratio of 1:0.5, ball-to-material ratio of 5:1, to obtain pretreated lithium mica powder;

[0051] S3, mixing the pretreated lithium mica powder of step S2 and 98%v / v concentrated sulfuric acid according to the ratio of 1:0.5, drying at 120℃ for 25min, then low-temperature roasting, specifically: roasting at 350℃ for 40min, to obtain pre-roasted material;

[0052] S4, high-temperature roasting the pre-roasted material of step S3, specifically: roasting at 650℃ for 2h, forming clinker, after the clinker is cooled, grinding the clinker into powder, the particle size is controlled at 150 mesh, ready for use;

[0053] S5, water immersion of the ground clinker of step S4, water immersion at 40℃, 200rpm, leaching for 30min, filtering the leaching solution, impurity removal and purification, lithium precipitation, drying and crushing, to obtain lithium carbonate.

[0054] Comparative Example 1

[0055] The roasting process of this comparative example, the specific steps include:

[0056] S1, crushing the lithium mica, passing through a 200-mesh sieve, to obtain lithium mica powder;

[0057] S2, mixing the lithium mica powder of step S1 and 98%v / v concentrated sulfuric acid according to the ratio of 1:0.5, to obtain a mixture;

[0058] S3, drying the mixture of step S2 at 200℃ for 30min, roasting, specifically: roasting at 900℃ for 60min, after the roasting of the clinker is cooled, grinding the clinker into powder, the particle size is controlled at 60 mesh, ready for use;

[0059] S4, water immersion of the ground clinker of step S3, water immersion at 35°C, 150 rpm, leaching for 40 min, filtration of the leaching solution, impurity removal and purification, lithium precipitation, and drying and crushing to obtain lithium carbonate.

[0060] Comparative Example 2

[0061] The difference from Example 1 is that no wet grinding of citric acid is performed, and the rest is consistent with Example 1.

[0062] The calcination process of the present comparative example includes the following specific steps:

[0063] S1, crushing and grinding of the lepidolite, dry ball milling of the crushed lepidolite and tannic acid at a mass ratio of 1:0.4 for 15 min, ball-to-material ratio of 8:1, to obtain pretreated lepidolite powder;

[0064] S2, mixing of the pretreated lepidolite powder of step S1 and 98% v / v concentrated sulfuric acid at a mass ratio of 1:0.5, drying at 130°C for 25 min, and then low-temperature calcination, specifically calcination at 350°C for 50 min, to obtain pre-calcined material;

[0065] S3, high-temperature calcination of the pre-calcined material of step S2, specifically calcination at 650°C for 1.5 h to form clinker, and after cooling of the clinker, grinding to a particle size of 60 mesh for standby;

[0066] S4, water immersion of the ground clinker of step S3, water immersion at 35°C, 150 rpm, leaching for 40 min, filtration of the leaching solution, impurity removal and purification, lithium precipitation, and drying and crushing to obtain lithium carbonate.

[0067] Comparative Example 3

[0068] The difference from Example 1 is that no low-temperature calcination is performed, and the rest is consistent with Example 1.

[0069] The calcination process of the present comparative example includes the following specific steps:

[0070] S1, wet grinding of the lepidolite and 40 wt% citric acid solution at a solid-to-liquid ratio of 1:13 g / mL for 25 min to obtain lepidolite powder;

[0071] S2, dry ball milling of the lepidolite powder of step S1 and tannic acid at a mass ratio of 1:0.4 for 15 min, ball-to-material ratio of 8:1, to obtain pretreated lepidolite powder;

[0072] S3, mixing the pretreated lepidolite powder of step S2 and 98% v / v concentrated sulfuric acid with a mass ratio of 1:0.5, drying at 130℃ for 25 min, and then high-temperature calcining, specifically, calcining at 650℃ for 1.5 h to form clinker, grinding the clinker after cooling, and controlling the particle size to 60 mesh for standby use;

[0073] S4, water immersion of the ground clinker of step S3, water immersion at 35℃ and 150 rpm for 40 min, filtering the leaching solution, removing impurities, precipitating lithium, drying and crushing to obtain lithium carbonate.

[0074] Test Example 1

[0075] The transformation rates of various elements according to the process methods of Examples 1-4 and Comparative Examples 1-3 are shown in Table 1, based on the residue.

[0076] The transformation rate of a certain element = (soluble content of the certain element - total content of the certain element) x 100%.

[0077] Table 1

[0078]

[0079] As can be seen from Table 1, the process methods of Examples 1-4 of the present application can improve the transformation rate of lithium, while also improving the leaching rate of valuable elements and reducing the leaching rate of impurities, and have good application prospects.

[0080] Test Example 2

[0081] The energy consumption and product conditions in the process according to the process methods of Examples 1-4 and Comparative Examples 1-3 are shown in Table 2, based on one ton of lepidolite.

[0082] Table 2

[0083]

[0084] As can be seen from Table 2, the process methods of Examples 1-4 of the present application have low energy consumption, reduce impurity leaching, and improve product yield, and have good application prospects.

[0085] The above only describes preferred embodiments of the present application and is not intended to limit the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A calcination process for improving the lithium conversion rate in lepidolite, characterized in that, Includes the following steps: S1. Wet grinding of lepidolite and citric acid solution for 20-30 minutes to obtain lepidolite powder; S2. Dry ball mill the lepidolite powder and tannic acid from step S1 for 10-20 minutes to obtain pretreated lepidolite powder. S3. Mix the pretreated lithium mica powder from step S2 with concentrated sulfuric acid, dry it, and calcine it at 300-400℃ for 40-60 minutes to obtain the pre-calcined material. S4. The pre-calcined material from step S3 is calcined at 600-700℃ for 1-2 hours to form clinker. After cooling, it is ground into powder for later use. S5. The pulverized clinker from step S4 is soaked in water, the leachate is filtered, impurities are removed and purified, lithium is precipitated, and the material is dried and pulverized to obtain lithium carbonate.

2. The calcination process for improving lithium conversion rate in lepidolite as described in claim 1, characterized in that, In step S1, the mass concentration of the citric acid solution is 30%-50%; the solid-liquid ratio of the lepidolite and the citric acid solution is 1:10-15 g / mL.

3. The calcination process for improving lithium conversion rate in lepidolite as described in claim 1, characterized in that, In step S1, the mass ratio of the lithium mica powder to tannic acid is 1:0.3-0.

5.

4. The calcination process for improving lithium conversion rate in lepidolite as described in claim 1, characterized in that, In step S2, the ball-to-material ratio of the dry ball mill is 5-10:

1.

5. The calcination process for improving lithium conversion rate in lepidolite as described in claim 1, characterized in that, In step S3, the volume concentration of the concentrated sulfuric acid is 96%-98%; the mass ratio of the pretreated lithium mica powder to the concentrated sulfuric acid is 1:0.4-0.

6.

6. The calcination process for improving lithium conversion rate in lepidolite as described in claim 1, characterized in that, In step S3, the drying temperature is 100-150℃ and the time is 15-30 minutes.

7. The calcination process for improving lithium conversion rate in lepidolite as described in claim 1, characterized in that, In step S4, the particle size of the powder is controlled between 60 and 150 mesh.

8. The calcination process for improving lithium conversion rate in lepidolite as described in claim 1, characterized in that, In step S5, the water immersion is performed at 30-40℃ and 100-200 rpm for 30-50 minutes.

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