Method for extracting lithium from amblygonite

Abstract

The invention discloses a method for extracting lithium from amblygonite, which is characterized in that when the content of silicon dioxide in the amblygonite is higher, the amblygonite comprises the following components in percentage by mass: greater than or equal to 5% of silicon dioxide, less than 0.50% of moisture and greater than 1.2 of Al / P molar ratio, and a one-section roasting and diatomite process is adopted; the addition amount of the acid is 1.5-1.8 times that of the sulfuric acid, and roasting is performed at 280-320 DEG C under 8HZ. The diatomite is adopted, so that the material rarefaction can be delayed, the use amount of the sulfuric acid can be increased, and the total yield can reach 80-85%; when the content of silicon dioxide in the amblygonite is low, the content of silicon dioxide is less than 5%, the water content is more than 0.50%, the molar ratio of Al to P is less than 1.2, and a two-stage roasting process is adopted; the total amount of the added acid is 1.8-2.6 times of the total amount of the added acid, 1.0-1.6 times of the amount of the added acid is added in the first-section process, and roasting is performed at 280-320 DEG C under 10HZ; in the second-stage process, the acid adding amount is 0.5-1.2, and roasting is performed at 320-340 DEG C under 10HZ; the method does not have a slime phenomenon after a long time, and the total yield can reach 85-92%.

Description

Technical Field

[0001] The present invention relates to the field of spodumene treatment, and particularly to a method for extracting lithium from spodumene. Background Art

[0002] At present, there are the following several processes for treating spodumene in the market. The method of using sulfuric acid + sulfuric acid and hydrochloric acid for acidification roasting to treat spodumene materials introduces sulfates to solve the problems of acid agglomeration and sludging of lithium aluminum phosphate, which will cause a high liquid salt content, a high sodium sulfate / lithium carbonate ratio, and a reduction in the overall yield. The method of using two-stage conversion to prepare lithium carbonate has a first-stage temperature of 150 - 400°C and a second-stage temperature of 550 - 900°C. A reducing agent also needs to be added during the process. The second-stage temperature is relatively high, and the costs of natural gas and auxiliary materials increase. Summary of the Invention

[0003] In order to overcome the problems existing in the prior art, the present invention adopts different treatment processes for spodumene with different silicon contents. For spodumene with a high silicon content, low moisture, and an aluminum / phosphorus molar ratio > 1.2, a one-stage acidification roasting + diatomite process is adopted; for spodumene with a low silicon content, high moisture, and an aluminum / phosphorus molar ratio ≤ 1.2, a two-stage acidification roasting process is adopted.

[0004] The present invention provides a method for extracting lithium from spodumene. For spodumene with a relatively high silicon dioxide content, calculated by mass fraction, silicon dioxide ≥ 5%, moisture < 0.50%, and an Al / P molar ratio > 1.2, a one-stage roasting + diatomite process is adopted; for spodumene with a relatively low silicon dioxide content, calculated by mass fraction, silicon dioxide < 5%, moisture > 0.50%, and an Al / P molar ratio ≤ 1.2, a two-stage roasting process is adopted. Further, the diatomite is industrial-grade diatomite. The industrial-grade diatomite is weakly alkaline, with a main content of more than 85% and a moisture content within 1%. Using diatomite can delay the sludging of the material.

[0005] Further, when adopting the one-stage roasting + diatomite process, the amount of acid added is 1.5 - 1.8 times the lithium mass content, and roasting is carried out at 8HZ and 280 - 320°C.

[0006] Further, 98% concentrated sulfuric acid is used when adding acid.

[0007] Further, the mass ratio of diatomite to spodumene material ≤ 2.5%.

[0008] Further, when adopting the one-stage roasting + diatomite process, by increasing the amount of sulfuric acid used, the total yield can reach between 80 - 85%.

[0009] Furthermore, when adopting the two-stage roasting process, the total amount of acid added is 1.8 - 2.6 times the lithium mass content. For the first-stage process, the acid addition amount is 1.0 - 1.6 times, roasting at 10HZ and 280 - 320°C; for the second-stage process, the acid addition amount is 0.5 - 1.2, roasting at 10HZ and 320 - 340°C. There is no phenomenon of sludging for a long time, and the total recovery rate can reach 85 - 92%.

[0010] Furthermore, adding non-ionic polyacrylamide can improve the leaching and filtration rate of lithiophilite.

[0011] Furthermore, for the hydrogen fluoride and acid mist gases generated during the process, the entire process uses closed stirring, an external spray tower system, closed transportation, and a negative pressure inside the kiln. Through the use of a plate and frame settler + 1-stage spray + electric demister + three-stage spray + chimney exhaust treatment for the above system, the water in the spray tower is sent for leaching or directly for sewage treatment. Beneficial effects

[0012] 1. For the two processes adopted in the present invention, the first-stage roasting + diatomaceous earth process; using diatomaceous earth can delay the sludging of materials, increase the sulfuric acid consumption, and the total recovery rate can be between 80 - 85%; adopting the two-stage roasting process; there is no sludging phenomenon for a long time, and the total recovery rate can reach 85 - 92%.

[0013] 2. For the two processes adopted in the present invention, the temperature in the heating section of the kiln is less than 340°C to ensure the lowest energy consumption. For the hydrogen fluoride and acid mist gases generated during the process, the entire process uses closed stirring (with an external spray tower system), closed transportation, and a negative pressure inside the kiln. Through the use of a plate and frame settler + 1-stage spray + electric demister + three-stage spray + chimney exhaust treatment for the above system, the water in the spray tower is sent for leaching or directly for sewage treatment. Only through the above process can the acidification roasting process of lithiophilite be truly industrialized.

[0014] 3. Using non-ionic amide filter aid can solve the problem of difficult filtration of the filter press and improve related production efficiency problems.

[0015] 4. Using a kneader for the acid mixing process of lithiophilite has the characteristics of more uniform mixing, less likely to get stuck in the pot, and high practicability compared with common plow blade mixers and double-shaft acid mixers. Specific embodiments

[0016] The present invention will be described in detail below in conjunction with the embodiments. Example 1

[0017] A batch of 438 tons of relatively high-purity spodumene materials, with a main silica content of 3.5%, an aluminum-to-phosphorus molar ratio of 1.0, a lithium content of 3.20%, a moisture content of 0.85%, and particle size of irregular small particles of 0.24 cm. After passing through a ball mill and a powder separator, the target of 80% sieve passing rate for 200 mesh is achieved, and a two-stage roasting process is adopted. First-stage process: According to 500±20 kg of materials, 98% concentrated sulfuric acid is added at 1.6 times the lithium mass content. After 5 minutes of grinding, the mixing of sulfuric acid and materials is completed. Using cooling water to control the kneader within the range of 85°C, it is spirally conveyed into the acidification kiln. The heating zone is controlled at 280 - 300°C, the main kiln rotation speed is 8HZ, and the cooling kiln rotation speed is 10HZ. After passing through a hammer crusher, it is stored in a ton bag, and the residual acid amount is 0.05%; Second-stage process: 500±20 kg of the above first-stage materials, 98% concentrated sulfuric acid is added at 0.5 times the lithium content. After 5 minutes of grinding, the mixing of sulfuric acid and materials is completed. Using cooling water to control the kneader within the range of 85°C, it is conveyed into the acidification kiln. The heating zone is controlled at 300 - 320°C, the main kiln rotation speed is 8HZ, and the cooling kiln rotation speed is 10HZ. After passing through a hammer crusher, the particles are initially crushed. The materials are conveyed into the leaching pot for leaching. Using a grinding pump to complete the secondary crushing of the roasted materials, and then using 10 million non-ionic polyacrylamide to solve the problem of difficult filtration of spodumene materials (added at two ten-thousandths in water below 50°C and prepared at three thousandths; this reagent can be prepared using the leaching mother liquor instead of tap water, and will not dilute the liquid lithium content). For the hydrogen fluoride and acid mist gases generated during the process, the entire process uses closed stirring (connected to an external spray tower system), closed conveying, and overall negative pressure inside the kiln. Through the use of a plate and frame settler + 1-stage spray + electric demister + three-stage spray + chimney exhaust treatment for the above system, the water in the spray tower is sent for leaching or directly for sewage treatment. After machine washing, the residual lithium in the slag is 0.15%, the dry slag ratio is 1, the leaching yield is 95.31%, the impurity removal yield is 98%, the yield of converting brine to lithium carbonate is 98%, and the overall yield is 91.5%. Example 2

[0018] A batch of 100 tons of relatively high-purity spodumene materials, with a main silica content of 7%, an aluminum-to-phosphorus molar ratio of 1.6, a lithium content of 2.58%, a moisture content of 0.30%, and particle size of irregular small particles of 0.18 cm. After passing through a ball mill and a powder separator, the target of 80% passing rate through 200 mesh is achieved, and a one-stage acidification roasting + diatomite process is adopted. According to 600 ± 20 kg of the materials, 12.5 Kg of diatomite is added, and 98% concentrated sulfuric acid is added at 1.7 times the lithium mass content. After 6 minutes of grinding, the mixing of sulfuric acid and the materials is completed. The acid mixing equipment is controlled within 85°C using cooling water, and then transported to the acidification kiln by belt. The heating zone is controlled at 280 - 300°C, the main kiln rotation speed is 8HZ, and the cooling kiln rotation speed is 10HZ. After passing through a hammer crusher, it is stored in a ton bag, with a residual acid amount of 1.0%. Then, a grinding pump is used to complete the secondary crushing of the roasted materials. 10 million non-ionic polyacrylamide is used to solve the problem of difficult filtration of spodumene materials (added at a rate of two ten-thousandths in water below 50°C and prepared at three thousandths; this reagent can be prepared using the leaching mother liquor instead of tap water, without diluting the liquid lithium content). For the hydrogen fluoride and acid mist gases generated during the process, the entire process uses closed stirring (connected to an external spray tower system), closed transportation, and overall negative pressure inside the kiln. Through the use of a plate and frame settler + 1-stage spray + electric demister + three-stage spray + chimney for external discharge treatment, the water from the spray tower is sent for leaching or directly for sewage treatment. After machine washing, the lithium content in the residue is 0.30%, the dry residue ratio is 0.96, the leaching yield is 88%, the impurity removal yield is 98%, the yield of converting brine to lithium carbonate is 98%, and the overall yield is 84.5%.

Claims

1. A method for extracting lithium from spodumene, characterized in that, For spodumene with a relatively high silica content, where the silica content is ≥5% by mass fraction, the moisture content is <0.50%, and the Al / P molar ratio is >1.2, a one-stage roasting + diatomite process is adopted; for spodumene with a relatively low silica content, where the silica content is <5% by mass fraction, the moisture content is >0.50%, and the Al / P molar ratio is ≤1.2, a two-stage roasting process is adopted.

2. The method for extracting lithium from spodumene according to claim 1, characterized in that, The diatomite is industrial-grade diatomite. The industrial-grade diatomite is weakly alkaline, with a main content of more than 85% and a moisture content within 1%. Using diatomite can delay the sludging of the material.

3. The method for extracting lithium from spodumene according to claim 2, characterized in that, When adopting the one-stage roasting + diatomite process, the amount of acid added is 1.5 - 1.8 times the lithium mass content, and roasting is carried out at 8HZ and 280 - 320°C.

4. The method for extracting lithium from spodumene according to claim 3, characterized in that, 98% concentrated sulfuric acid is used when adding acid.

5. The method for extracting lithium from spodumene as claimed in claim 4, characterized in that, The mass ratio of diatomite to spodumene material is ≤2.5%.

6. The method for extracting lithium from spodumene according to claim 5, wherein When adopting the one-stage roasting + diatomite process, by increasing the amount of sulfuric acid used, the total recovery rate can reach between 80 - 85%.

7. The method for extracting lithium from spodumene according to claim 6, characterized in that, When adopting the two-stage roasting process, the total amount of acid added is 1.8 - 2.6 times the lithium mass content. For the first-stage process, the amount of acid added is 1.0 - 1.6 times, and roasting is carried out at 10HZ and 280 - 320°C; for the second-stage process, the amount of acid added is 0.5 - 1.2 times, and roasting is carried out at 10HZ and 320 - 340°C. There is no sludging phenomenon for a long time, and the total recovery rate can reach 85 - 92%.

8. The method for extracting lithium from spodumene according to claim 7, characterized in that, Non-ionic polyacrylamide is added to improve the leaching and filtration rate of spodumene.

9. The method for extracting lithium from spodumene according to claim 8, characterized in that, For hydrogen fluoride and acid mist gases generated during the process, the whole process uses closed stirring, an external spray tower system, closed transportation, and a negative pressure inside the kiln. Through the use of a plate and frame settler + 1-stage spray + electric demister + three-stage spray + chimney exhaust treatment for the above system, the water in the spray tower is sent for leaching or directly for sewage treatment.