CN-121992223-A - Lithium mica normal-pressure high-efficiency lithium extraction method based on synergistic activation and targeted impurity removal

Abstract

The invention belongs to the technical field of hydrometallurgy and comprehensive utilization of resources, and relates to a method for extracting lithium from lepidolite at normal pressure and high efficiency based on synergistic activation and targeted impurity removal. The method comprises the following steps of mechanochemical activation-pre-deconstruction, hydrochloric acid normal pressure enhanced leaching, fluorine-aluminum co-precipitation and recycling, deep iron removal, calcium-magnesium targeted precipitation and lithium recovery. The method comprises the steps of optimizing a lithium extraction process, carrying out crystal pre-deconstruction on lepidolite concentrate by combining mechanical and chemical activation, creating extremely high reaction activity for subsequent acid leaching reaction under normal pressure, removing fluorine, aluminum and iron by precisely controlling reaction conditions, and finally adding a composite precipitant to deeply remove calcium and magnesium. The lithium extraction and impurity removal method has the advantages of simple process flow, high lithium recovery rate, low impurity content and wide applicability.

Inventors

• WEI DONGDONG
• DING QIANG
• ZHANG HUI
• YU HAO
• YAO LI
• SU KE
• WEI YUN
• PAN RUI
• LIAO XIN
• PAN LONGHUI
• LIAO QIANG
• XIAO ZHEN

Assignees

• 宜丰九岭锂业有限公司

Dates

Publication Date

20260508

Application Date

20260212

Claims (8)

1. 1. The method for extracting lithium from lepidolite at normal pressure and high efficiency based on synergistic activation and targeted impurity removal is characterized by comprising the following steps of: (1) Mixing lepidolite concentrate with a crystal form conversion auxiliary agent, and performing mechanochemical activation in a planetary ball mill to obtain activated powder; (2) Reacting the activated powder obtained in the step (1) with hydrochloric acid for 2-3 hours under normal pressure, synchronously adding a selective scale inhibitor into a reaction system, and carrying out solid-liquid separation after the reaction is finished to obtain a leaching solution; (3) Slowly adding a calcium source into the leaching solution obtained in the step (2), accurately controlling the pH to 3.5-4.5, stirring and reacting for 0.5-1h, and carrying out solid-liquid separation to obtain a filtrate A; (4) Regulating the pH value of the filtrate A in the step (3) to 5.0-5.5 by alkali, completely hydrolyzing and precipitating Fe 3+ , and filtering to obtain filtrate B; (5) Heating the filtrate B obtained in the step (4) to 60-80 ℃, adding a composite precipitator, stirring and reacting for 0.5-1.5h, and filtering to obtain a high-purity lithium chloride solution; (6) Concentrating the high-purity lithium chloride solution obtained in the step (5) to obtain a lithium chloride product, or adding sodium carbonate to precipitate to obtain battery grade lithium carbonate.
2. 2. The method for extracting lithium from lepidolite at normal pressure and high efficiency based on synergistic activation and targeted impurity removal according to claim 1 is characterized in that in the step (1), the crystal form conversion auxiliary agent is at least one of sodium chloride and potassium chloride, and the mass ratio of lepidolite concentrate to the crystal form conversion auxiliary agent is 100:1-5.
3. 3. The method for extracting lithium from lepidolite at normal pressure and high efficiency based on synergistic activation and targeted impurity removal according to claim 1, wherein in the step (1), the particle size D90 of the activated powder is less than or equal to 15 μm.
4. 4. The method for extracting lithium from lepidolite at normal pressure and high efficiency based on synergistic activation and targeted impurity removal according to claim 1, wherein in the step (2), the concentration of hydrochloric acid is 5-8mol/L, and the solid-liquid ratio g/mL of activated powder to hydrochloric acid is 1:3-5.
5. 5. The method for extracting lithium from lepidolite at normal pressure and high efficiency based on synergistic activation and targeted impurity removal according to claim 1, wherein in the step (2), the scale inhibitor is citric acid or sodium polyacrylate, and the addition amount of the scale inhibitor is 0.5-2% of the mass of the lepidolite concentrate.
6. 6. The method for extracting lithium from lepidolite at normal pressure and high efficiency based on synergistic activation and targeted impurity removal according to claim 1, wherein in the step (2), the reaction temperature is 90-100 ℃.
7. 7. The method for extracting lithium from lepidolite at normal pressure and high efficiency based on synergistic activation and targeted impurity removal according to claim 1, wherein in the step (3), the calcium source is Ca (OH) 2 or CaCl 2 .
8. 8. The method for extracting lithium from lepidolite at normal pressure and high efficiency based on synergistic activation and targeted impurity removal according to claim 1, wherein in the step (5), the composite precipitant is a mixture of sodium phosphate and sodium oxalate in a molar ratio of 1:0.5-1.5.

Description

Lithium mica normal-pressure high-efficiency lithium extraction method based on synergistic activation and targeted impurity removal Technical Field The invention belongs to the technical field of hydrometallurgy and comprehensive utilization of resources, and relates to a method for extracting lithium from lepidolite at normal pressure and high efficiency based on synergistic activation and targeted impurity removal. Background Lepidolite is an important lithium resource, and efficient lithium extraction is challenging. The traditional sulfuric acid method or sulfate roasting method has high energy consumption and heavy waste gas pollution, and lithium is easy to be wrapped and lost due to the generation of fluorosilicate double salt. Although the hydrochloric acid method has strong reaction activity, the direct normal pressure leaching has technical bottlenecks, such as dynamic limitation, the stable aluminosilicate crystal structure of lepidolite is difficult to be effectively destroyed under normal pressure and medium acid concentration, the lithium leaching rate is generally lower than 85%, the economical efficiency is poor, and the leaching solution has high concentration of Al 3+、Fe3+、Ca2+、Mg2+ and F -, which are mutually interfered to form stable complex, the traditional segmented precipitation method has complicated steps, high reagent consumption, and is difficult to deeply remove calcium and magnesium, thereby affecting the purity of the final lithium product. Attempts have been made in the prior art to improve the lithium extraction effect of lepidolite, but new contradictions are often faced. On the one hand, fluoride enhanced leaching technology adopted for breaking through the leaching rate bottleneck inevitably introduces more destructive fluorine pollution and corrosion problems, and on the other hand, solvent extraction technology used for realizing deep separation of impurities is used as reference, and although the purification effect is still available, the high investment and operation cost, complex operation units and potential organic solvent environmental risks cause the technology to lack universality in the mineral hydrometallurgy industry pursuing cost benefits. Therefore, developing a green low-cost method that realizes high lithium leaching rate under normal pressure and can realize deep purification of impurities through a concise flow is a technical problem to be solved in the field. Disclosure of Invention Aiming at the defects, the invention provides a lithium mica normal-pressure high-efficiency lithium extraction method based on synergistic activation and targeted impurity removal, which has the advantages of simple process flow, high lithium recovery rate, low cost and environmental friendliness, and can effectively solve the dilemma of dynamic restriction and purification in the prior art. The invention aims to provide a lepidolite normal-pressure high-efficiency lithium extraction method based on synergistic activation and targeted impurity removal, which comprises the following steps of: (1) In the step, under the strong mechanical force, na + or K + in the crystal form conversion auxiliary agent can be partially embedded into an interlayer structure of lepidolite under the drive of a high-activity site on the surface of a new mineral, preliminary ion exchange is carried out, a large number of lattice defects and microcracks are generated, and the stable silicon oxygen tetrahedron-aluminum oxygen octahedron layered structure is pre-deconstructed in the process, so that the specific surface area and the chemical activity are greatly increased, and the dynamic advantage is created for the subsequent acid leaching. (2) The activated powder obtained in the step (1) reacts with hydrochloric acid for 2-3 hours under normal pressure, a selective scale inhibitor is synchronously added into a reaction system, after the reaction is completed, solid-liquid separation is carried out, so as to obtain a leaching solution, in the step, activated minerals react with the hydrochloric acid, lithium, aluminum, iron, potassium and the like enter the solution in an ionic form, F - and silicic acid are released simultaneously, namely, lithium and impurities are dissolved out, and then the dissolved silicic acid is very easy to react with F -、Na+/K+ under an acid leaching environment to generate indissolvable fluorosilicate (such as Na 2SiF4) which is wrapped on the surfaces of unreacted mineral particles to block mass transfer, so that the method is a main reason for causing low conventional leaching rate. The added scale inhibitor citric acid or sodium chloroacrylate can be combined with silicic acid molecules or generated SiF 62- preferentially, and through steric hindrance and electrostatic repulsion, the nucleation and growth of the scale inhibitor citric acid or sodium chloroacrylate are inhibited, the densification of the solid fluorosilicate film is prevented, so that the smoothness