A method for smelting lithium carbonate to float lepidolite from evaporite salt

Abstract

The application discloses a method for floating lepidolite by using lithium carbonate smelting evaporation salt, relates to the technical field of hydrometallurgy, and is characterized by the following steps: dissolving lithium carbonate smelting evaporation salt by adding water to obtain an alkaline solution; mixing the alkaline solution with a lepidolite ore slurry to adjust the slurry, and adding a collector to float lepidolite concentrate. The method uses lithium carbonate smelting evaporation salt as an adjusting agent, reduces the beneficiation cost, and improves the lepidolite concentrate grade and the comprehensive recovery rate of lithium metal.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, and in particular to a method for smelting evaporative salt flotation of lepidolite using lithium carbonate. Background Technology

[0002] my country's lithium resources mainly originate from salt lakes, spodumene, and lepidolite, with abundant reserves ranking fourth in the world. They are primarily concentrated in Qinghai, Tibet, Sichuan, and Jiangxi provinces. As a major global producer and consumer of lithium products, China faces a supply shortage. Lepidolite, as a crucial component of lithium resources, has become a research hotspot due to its efficient utilization.

[0003] Flotation of lepidolite requires flotation reagents, typically collectors, frothers, and modifiers. Collectors primarily adhere to the surface of lepidolite particles and make them hydrophobic; frothers help create and stabilize foam; and modifiers primarily improve the selectivity of chemicals during flotation, ensuring effective lithium ore flotation. Commonly used modifiers include soda ash and water glass. However, these commonly used modifiers are relatively expensive and have limited effects.

[0004] The process of smelting lithium carbonate from lepidolite mainly includes roasting, leaching, impurity removal, and evaporation. Through roasting and leaching operations, the leaching slurry is filtered and separated to obtain the leachate. Li₂O and SO₄ in the mica ore are then separated. 2- The soluble salt Li₂SO₄ is transferred to the leachate. However, during the roasting process, in addition to alkali metals reacting with sulfuric acid to produce soluble sulfates, other elements such as iron, aluminum, calcium, and magnesium also react with sulfuric acid to produce their corresponding sulfates. Although some impurities are removed during leaching, the leachate still contains a large amount of inorganic salt impurities, which need to be purified. The leaching solution is often purified by alkalization to remove calcium. The leachate is alkalized with lime milk to raise the pH, causing magnesium and iron to hydrolyze into hydroxide precipitates. Then, sodium carbonate solution reacts with calcium sulfate to produce calcium carbonate precipitate, thus removing calcium from the leachate and calcium introduced by the lime milk. The alkalized calcium-removed slurry undergoes liquid-solid separation, and the resulting solution is the purified solution. Because the lithium sulfate concentration in the purified solution is low, the lithium precipitation rate is low, so it needs to be concentrated by evaporation in a triple-effect evaporator. During this evaporation process, a large amount of inorganic salts precipitate out, called evaporated salt. This evaporated salt contains a large amount of carbonate and bicarbonate ions, and its aqueous solution is alkaline, and it also contains a certain amount of lithium ions. The evaporated salt is partially returned to the leaching process to recover lithium metal, but due to its low content, the recycling rate is low, and large-scale stockpiling will have an environmental impact. Summary of the Invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a method for flotation of lepidolite using lithium carbonate smelting evaporation salt. The method uses lithium carbonate smelting evaporation salt as a modifier to reduce the beneficiation cost and at the same time improve the grade of lepidolite concentrate and the overall recovery rate of lithium metal.

[0006] The present invention proposes a method for flotation of lepidolite using lithium carbonate smelting evaporation salt, which involves dissolving lithium carbonate smelting evaporation salt in water to obtain an alkaline solution; mixing the alkaline solution with lepidolite slurry to adjust the slurry; and adding a collector to float out the lepidolite concentrate.

[0007] Furthermore, the lithium carbonate smelting evaporating salt is an inorganic salt precipitated during the evaporation process of lithium mica after roasting, leaching, impurity removal, and evaporation treatment during the production of lithium carbonate from lithium mica; the lithium carbonate smelting evaporating salt contains 0.01%-5% Li2O, and the pH of the alkaline solution obtained by dissolving it in water is 10-14.

[0008] Furthermore, the alkaline solution is mixed with the lepidolite slurry for 5-10 minutes, and the pH of the mixed system is controlled to be 7.0-8.0.

[0009] Furthermore, the collector is composed of a compound of dodecylamine and paraffin soap; the mass ratio of the dodecylamine to paraffin soap is 1:2-5.

[0010] Furthermore, the process of adding a collector to float lepidolite concentrate also includes: reusing the filtrate after the lepidolite concentrate has been filtered out by flotation into the lepidolite slurry for mixing and conditioning.

[0011] Furthermore, the lithium content in the filtrate is 5-2000 mg / L.

[0012] Furthermore, after the filtrate is reused 5-20 times, lithium-rich recycled water is obtained and reused in the lepidolite leaching process.

[0013] Furthermore, the lithium content in the lithium-rich recycled water is 2-10 g / L.

[0014] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in the following aspects:

[0015] 1. This invention uses lithium carbonate smelting evaporation salt to replace soda ash and other modifiers, reducing the reagent cost of lepidolite beneficiation and effectively recovering soluble lithium, thereby improving the lithium recovery rate.

[0016] 2. In this invention, lithium ions in the lithium carbonate smelting evaporation salt can optimize the surface properties of lepidolite, increase the interaction between lepidolite and the collector, and improve the indicators of lepidolite flotation concentrate.

[0017] This invention uses lithium carbonate smelting evaporation salt as a modifier, which reduces ore beneficiation costs while improving the grade of lepidolite concentrate and the overall recovery rate of lithium metal. Attached Figure Description

[0018] Figure 1 This is a process route diagram for the flotation of lepidolite using evaporated salts in the smelting of lithium carbonate, as proposed in this invention. Detailed Implementation

[0019] The technical solution of the present invention will now be described in detail through specific embodiments.

[0020] Example 1

[0021] A method for flotation of lepidolite using evaporated salts in the smelting of lithium carbonate, such as... Figure 1 As shown, the steps are as follows:

[0022] Step 1): A lithium carbonate smelter in Yifeng County, Jiangxi Province, produces evaporated salt. The evaporated salt, a byproduct of lithium carbonate smelting, is dissolved in water in a stirred tank at a liquid-to-solid ratio of 2:1 to prepare an alkaline solution with a pH of 10.5.

[0023] Step 2): Add the above alkaline solution to the lepidolite slurry in the mixing tank and mix for 6 minutes to adjust the pH of the slurry to 7.3. Then add a collector (a mixed collector prepared by mixing dodecylamine and paraffin soap in a mass ratio of 1:2) at a rate of 400g / t of raw ore. The lepidolite concentrate is then floated in the flotation machine using conventional methods.

[0024] Step 3): The above-mentioned lepidolite concentrate was filtered and dehydrated, and the lepidolite was analyzed. The filtrate was then used to prepare a slurry, which was circulated 6 times to obtain lithium-rich recycled water with a lithium content of 3150 mg / L, which was returned to the smelting and leaching workshop.

[0025] In this embodiment, lithium carbonate smelting evaporation salt was used as a modifier for the flotation of lepidolite concentrate, and the lepidolite concentrate obtained from the flotation was tested. In addition, a 5% sodium carbonate solution was used as a modifier and the operation was carried out according to step 2) above as a comparative example. The results are shown in Table 1.

[0026] Table 1

[0027] Lithium mica concentrate grade / % 1.93 1.98 Lithium mica concentrate recovery rate / % 67.32 69.27

[0028] Example 2

[0029] A method for flotation of lepidolite using evaporated salts in the smelting of lithium carbonate, such as... Figure 1 As shown, the steps are as follows:

[0030] Step 1): A lithium carbonate smelter in Yifeng County, Jiangxi Province, produces evaporated salt. The evaporated salt, a byproduct of lithium carbonate smelting, is dissolved in water in a stirred tank at a liquid-to-solid ratio of 3:1 to prepare an alkaline solution with a pH of 10.3.

[0031] Step 2): Add the above alkaline solution to the lepidolite slurry in the slurry mixing tank and mix for 6 minutes to adjust the pH of the slurry to 7.1. Then add a collector (a mixed collector prepared by mixing dodecylamine and paraffin soap in a mass ratio of 1:3) at a rate of 400g / t of raw ore and float the lepidolite concentrate according to conventional flotation.

[0032] Step 3): The above-mentioned lepidolite concentrate was filtered and dehydrated, and the lepidolite was analyzed. The filtrate was then used to prepare a slurry, which was circulated four times to obtain lithium-rich recycled water with a lithium content of 2980 mg / L, which was returned to the smelting and leaching workshop.

[0033] In this embodiment, lithium carbonate smelting evaporation salt was used as a modifier for the flotation of lepidolite concentrate, and the lepidolite concentrate obtained from the flotation was tested. Furthermore, a 5% sodium carbonate solution was used as a modifier in step 2) above as a comparative example, and the results are shown in Table 2.

[0034] Table 2

[0035] Lithium mica concentrate grade / % 1.87 1.94 Lithium mica concentrate recovery rate / % 66.59 67.12

[0036] Example 3

[0037] A method for flotation of lepidolite using evaporated salts in the smelting of lithium carbonate, such as... Figure 1 As shown, the steps are as follows:

[0038] Step 1): A lithium carbonate smelting plant in Yifeng County, Jiangxi Province, produces evaporated salt. The evaporated salt, a byproduct of lithium carbonate smelting, is dissolved in water in a stirred tank at a liquid-to-solid ratio of 2:1 to prepare an alkaline solution with a pH of 11.0.

[0039] Step 2): Add the above alkaline solution to the lepidolite slurry in the slurry mixing tank and mix for 6 minutes to adjust the pH of the slurry to 7.8. Then add a collector (a mixed collector prepared by mixing dodecylamine and paraffin soap in a mass ratio of 1:4) at a rate of 400g / t of raw ore. The lepidolite concentrate is then obtained by conventional flotation.

[0040] Step 3): The above-mentioned lepidolite concentrate was filtered and dehydrated, and the lepidolite was analyzed. The filtrate was then used to prepare a slurry, which was circulated 8 times to obtain lithium-rich recycled water with a lithium content of 3879 mg / L, which was returned to the smelting and leaching workshop.

[0041] In this embodiment, lithium carbonate smelting evaporation salt was used as a modifier for the flotation of lepidolite concentrate, and the lepidolite concentrate obtained from the flotation was tested. Furthermore, a 5% sodium carbonate solution was used as a modifier in step 2) above as a comparative example (3), and the results are shown in Table 3.

[0042] Table 3

[0043] Lithium mica concentrate grade / % 1.91 2.02 Lithium mica concentrate recovery rate / % 67.33 69.72

[0044] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for flotation of lepidolite using evaporated salts in the smelting of lithium carbonate, characterized in that, The process involves dissolving lithium carbonate smelting evaporation salt in water to obtain an alkaline solution; mixing the alkaline solution with lepidolite slurry to adjust the slurry; and then adding a collector to float and extract lepidolite concentrate. The lithium carbonate smelting evaporating salt is an inorganic salt precipitated during the evaporation process of lithium mica after roasting, leaching, impurity removal, and evaporation treatment in the production of lithium carbonate from lithium mica. The lithium carbonate smelting evaporating salt contains 0.01%-5% Li2O, and the pH of the alkaline solution obtained by dissolving it in water is 10-14.

2. The method according to claim 1, characterized in that, Mix the alkaline solution with the lepidolite slurry for 5-10 minutes, and control the pH of the mixed system to be 7.0-8.

0.

3. The method according to claim 1, characterized in that, The collector is composed of dodecylamine and paraffin soap; the mass ratio of dodecylamine to paraffin soap is 1:2-5.

4. The method according to claim 1, characterized in that, Adding a collector to float lepidolite concentrate also includes: reusing the filtrate after the lepidolite concentrate has been filtered out by flotation into the lepidolite slurry for mixing and conditioning.

5. The method according to claim 4, characterized in that, The lithium content in the filtrate is 5-2000 mg / L.

6. The method according to claim 4 or 5, characterized in that, After the filtrate is reused 5-20 times, lithium-rich recycled water is obtained and reused in the lepidolite leaching process.

7. The method according to claim 6, characterized in that, The lithium content in the lithium-rich recycled water is 2-10 g / L.

Images