CN-121992222-A - Method for extracting lithium and thallium from lepidolite concentrate

CN121992222ACN 121992222 ACN121992222 ACN 121992222ACN-121992222-A

Abstract

The invention relates to the technical field of lithium extraction from concentrates, in particular to a method for extracting lithium and thallium from lepidolite concentrates. The method comprises the steps of adding a complex acid mixed complexing system and a surfactant into lepidolite concentrate, mixing, grinding, carrying out ultrasonic treatment, heating, leaching and filtering to obtain a lithium-containing leaching solution, mixing a thallium complexing agent, a diluting agent and an extracting agent to construct a first polar extraction system, adding the lithium-containing leaching solution into the first polar extraction system to carry out mixing and extraction to obtain a thallium-rich organic phase and a thallium-poor organic phase, desorbing the thallium-rich organic phase to obtain a thallium-rich solution and a thallium-poor organic phase, mixing the lithium complexing agent, the diluting agent and the extracting agent to construct a second polar extraction system, adding the raffinate into the second polar extraction system to carry out mixing and extraction to obtain a lithium complex, purifying, and eluting to obtain a Li + -rich solution. The main purpose of the invention is to provide a new choice for the method for extracting lithium and thallium from lepidolite concentrate.

Inventors

CHENG LILI
ZHOU HEPENG
FENG JINRU
LIU ZISHUAI
TANG XUEKUN
ZHANG YONGBING

Assignees

宜春江理锂电新能源产业研究院
江西理工大学

Dates

Publication Date: 20260508
Application Date: 20260206

Claims (10)

1. A method for extracting lithium and thallium from lepidolite concentrate, comprising the steps of: Adding a complex acid mixed complexing system and a surfactant into the lepidolite concentrate, mixing and grinding to form lepidolite concentrate solid content slurry, and then carrying out ultrasonic treatment on the lepidolite concentrate solid content slurry to obtain the lepidolite concentrate solid content slurry after ultrasonic cracking; heating and extracting the slurry with the solid content of the lepidolite concentrate after ultrasonic cracking, and filtering to obtain a lithium-containing leaching solution and lepidolite leaching residues; mixing a thallium complexing agent, a diluent and an extractant to construct a first polar extraction system, and then adding the lithium-containing leaching solution into the first polar extraction system for mixing and extracting to obtain a thallium-rich organic phase and a raffinate; desorbing the thallium-rich organic phase to obtain thallium-rich solution and thallium-poor organic phase; Mixing a lithium complexing agent, a diluent and an extractant to construct a second polar extraction system, adding the raffinate into the second polar extraction system to perform mixing and extraction to obtain a lithium complex, and purifying and eluting the lithium complex to obtain a Li-rich + solution.
2. The method according to claim 1, wherein the purification of the lithium complex comprises the steps of transferring the lithium complex into an ion exchange system, purifying with a resin to obtain a resin after adsorption of lithium, and eluting the resin after adsorption of lithium to obtain a Li + -rich solution.
3. The method according to claim 2, wherein the resin filler is 5-10L of resin per cubic meter of lithium complex, the flow rate of the lithium complex in the ion exchange system is 15-50L/h, the circulation time is 6-8 hours/period, the eluting eluent is 0.1-0.5 mol/L of dilute hydrochloric acid, the flow rate of the eluting is 0.5-0.8 bed volume/hour, and the pH of the Li + -rich solution is 1.0-1.5.
4. The method according to claim 2, wherein the resin is D201 strong acid sulfonic acid resin, and the resin after adsorption of lithium is D201 strong acid sulfonic acid resin after adsorption of lithium.
5. The method of claim 1, wherein the mass ratio of the lepidolite concentrate, the complex acid mixed complexing system and the surfactant is 1000:1000-1500:5.
6. The method according to claim 1, wherein the complex acid mixed complexing system comprises acid and nitrilotriacetic acid (NTA), the acid is one or two of citric acid and succinic acid, the concentration of the acid in the complex acid mixed complexing system is 0.15-0.25 mol/L, the concentration of the nitrilotriacetic acid (NTA) is 0.05-0.08 mol/L, and the molar ratio of the acid to the nitrilotriacetic acid is 3:1; And/or the mass ratio of the lepidolite concentrate to the complex acid complexing system is 1:1.0-1.5; and/or the surfactant is one or two of sodium dodecyl sulfate and sodium dodecyl sulfonate; And/or, the amount of the surfactant is 0.5wt% based on lepidolite concentrate; and/or the thallium complexing agent is dibenzo-18-crown-6-ether, and in the first polar extraction system, the concentration of the thallium complexing agent is 0.8-1.2 g/L; and/or the complexing agent of lithium is ethyl acetoacetate, and the concentration is 1.5-2.0 g/L; and/or the extractant is tributyl phosphate (TBP) solution with the concentration of 15-20 vol%; and/or, the diluent is sulfonated kerosene; And/or the pH value of the first polar extraction system is 4.0-4.5, the saponification rate is 40-65%, and the total phase ratio A/O of the aqueous phase and the organic phase in the first polar extraction system is 3-8:1, namely the volume ratio of the aqueous phase to the organic phase in the first polar extraction system is 3-8:1; And/or the desorbing agent is H 2 SO 4 aqueous solution, the concentration of H 2 SO 4 in the H 2 SO 4 aqueous solution is 1.0-1.5 mol/L, and the ratio of thallium-rich organic phase to desorbing agent is 3-5:1; and/or the pH value of the second polar extraction system is 5.5-6.0, the saponification rate is 40-65%, and the total phase ratio A/O of the aqueous phase and the organic phase in the second polar extraction system is 3-8:1, namely the volume ratio of the aqueous phase to the organic phase in the second polar extraction system is 3-8:1.
7. The method of claim 1, wherein the grinding is performed in a sand mill, the spindle rotation speed of the sand mill is 150-200 r/min, the stirring axis speed of the sand mill is 0.5-1.5 m/s, the ball ratio of the ball mill is 10:1, the grinding concentration of the ball mill is 65-70%, and the grinding time is 30-60 min; And/or the ultrasonic treatment conditions comprise that the ultrasonic frequency is 20-25 kHz, the power density is 320-350W/L, the treatment temperature is controlled to be 80-95 ℃, the treatment time is 45-60 min, continuous flow treatment is adopted, the slurry flow rate is 8-12L/min, and the cavitation number is controlled to be 0.8-1.2; And/or the heating leaching adopts a three-stage countercurrent water leaching process, the solid ratio of the leaching liquid in the heating leaching process is 4-5:1, the heating leaching temperature is 90-95 ℃, the heating leaching time is 180-240 min, the heating leaching is also accompanied by stirring, the stirring rotating speed is 300-400 rpm, and the filtering is suction filtration; And/or adding the lithium-containing leaching solution into the first polar extraction system for mixing and extracting, wherein the mixing and extracting comprises stirring and mixing by adopting a mechanical stirring mixer at a rotating speed of 250-300 rpm for 2-3 min, and the extracting is 3-4-stage countercurrent extraction; and/or adding the raffinate into the second polar extraction system for mixing and extracting, wherein the mixing and extracting are performed by adopting a mechanical stirring mixer at the rotating speed of 250-300 rpm for 2-3 min, and the extracting is 3-4-stage countercurrent extraction; and/or the desorption temperature is 25-35 ℃, the desorption time is 10-15 min, and the desorption stage number is 2.
8. The method according to claim 1, wherein the lepidolite concentrate comprises, by mass, 1.16% Li, 0.003% Tl, 1.39% F, 0.67% Na, 0.06% Mg, 12.11% Al, 20.56% Si, 0.13% P, 0.02% S, 0.02% Cl, 4.97% K, 0.07% Ca, 0.004% Nb, 0.009% W, 39.47% O, 0.02% Ti, 0.005% Cr, 0.24% Mn, 0.49% Fe, 0.003% Cu, 0.032% Zn, 0.006% Ga, 0.01% As, 0.61% Rb, 0.001% Zr, 0.06% Cs, and 0.009% Pb.
9. The lithium or thallium recovered by the method of any one of claims 1 to 8, wherein the extraction yield of lithium is greater than 97% and the extraction yield of thallium is greater than 99%.
10. Use of the method according to any one of claims 1 to 8 for extracting lithium and/or thallium from lepidolite concentrate.

Description

Method for extracting lithium and thallium from lepidolite concentrate Technical Field The invention relates to the technical field of lithium extraction from concentrates, in particular to a method for extracting lithium and thallium from lepidolite concentrates. Background The traditional lepidolite lithium extraction process mainly depends on high-temperature roasting (above 800 ℃) or strong acid leaching. The high-temperature roasting method needs to be carried out at a high temperature of 850-1000 ℃, and has the obvious defects that (1) the energy consumption is huge and the equipment abrasion is serious, (2) the associated thallium element is discharged along with the flue gas, a huge spraying purification system is required to be configured for capturing thallium in the flue gas, but a spraying mode is adopted for purification, high thallium wastewater with complex components and high treatment difficulty is generated, huge wastewater treatment cost is brought, and (3) part of unverified thallium can enter the subsequent lithium smelting slag (lithium slag) to cause the lithium slag to become thallium-rich dangerous waste, and thirty tons of lithium slag can be brought for each ton of lithium carbonate product. The potential environmental toxicity of thallium can cause thallium pollution, so that the waste residues are difficult to safely consume and recycle at present, most of the waste residues can only be rented for warehouse stacking, and the stacking management is carried out, so that serious solid waste disposal pressure and environmental hidden trouble are formed. Conventional acid leaching processes typically use HF or concentrated sulfuric acid. The method has the obvious defects of (1) strong corrosiveness and high acid consumption, and (2) low product separation selectivity and high waste liquid treatment cost caused by the fact that associated metals such as thallium and the like are easy to dissolve out along with lithium in an acidic environment. In recent years, there have been studies on attempts to extract lithium from lepidolite by a technique of mechanical activation and acid leaching, which can achieve a recovery rate of lithium of 90% or more, but which requires a high-temperature or long-time reaction, and which is complicated in process and high in energy consumption. In addition, the existing technology is mainly used for one-time extraction, so that the synergistic efficient recovery of lithium and thallium is difficult to realize, the water recycling rate is low, and the environmental load is high. Therefore, developing a new technology capable of efficiently activating lepidolite, selectively extracting lithium and realizing directional separation and recovery of associated thallium under mild conditions, thereby reducing pollution from the source and reducing energy consumption and solid waste environmental risk has become a key problem to be solved in the field. Disclosure of Invention Aiming at the problems existing in the prior art, the invention aims to provide a method for extracting lithium and thallium from lepidolite concentrate, so as to solve the problem that the existing lepidolite lithium extraction process cannot synchronously realize efficient activation, selective extraction of lithium and directional separation and recovery of associated thallium under mild conditions. The technical scheme of the invention is as follows: the invention provides a method for extracting lithium and thallium from lepidolite concentrate, which comprises the following steps: Adding a complex acid mixed complexing system and a surfactant into the lepidolite concentrate, mixing and grinding to form lepidolite concentrate solid content slurry, and then carrying out ultrasonic treatment on the lepidolite concentrate solid content slurry to obtain the lepidolite concentrate solid content slurry after ultrasonic cracking; heating and extracting the slurry with the solid content of the lepidolite concentrate after ultrasonic cracking, and filtering to obtain a lithium-containing leaching solution and lepidolite leaching residues; mixing a thallium complexing agent, a diluent and an extractant to construct a first polar extraction system, and then adding the lithium-containing leaching solution into the first polar extraction system for mixing and extracting to obtain a thallium-rich organic phase and a raffinate; desorbing the thallium-rich organic phase to obtain thallium-rich solution and thallium-poor organic phase; Mixing a lithium complexing agent, a diluent and an extractant to construct a second polar extraction system, adding the raffinate into the second polar extraction system to perform mixing and extraction to obtain a lithium complex, and purifying and eluting the lithium complex to obtain a Li-rich + solution. Firstly, by grinding lepidolite concentrate, the specific surface area of particles is remarkably improved, the interlayer spacing is damaged by mechanical extrusion