US-12623201-B2 - Lithium adsorbent and method for lithium extraction from salt lake

US12623201B2US 12623201 B2US12623201 B2US 12623201B2US-12623201-B2

Abstract

A lithium adsorbent includes an aluminum-based adsorbing material, a binder, and a wetting and dispersing agent. The binder includes at least one of a vinylidene fluoride-chlorotrifluoroethylene (VDF-CTFE) copolymer and a fluoroolefin-vinyl ether copolymer. The wetting and dispersing agent includes one or more of polyethylene glycol, sodium polyacrylate, polyvinyl alcohol, and formaldehyde condensate.

Inventors

Jialiang Wei
Hongye LIN
Junlan Lian

Assignees

BYD COMPANY LIMITED

Dates

Publication Date: 20260512
Application Date: 20221222
Priority Date: 20211228

Claims (9)

1 . A lithium adsorbent, comprising an adsorbing material, a binder, and a wetting and dispersing agent, wherein the binder comprises at least a vinylidene fluoride-chlorotrifluoroethylene copolymer, and the wetting and dispersing agent comprises one or more of polyethylene glycol, sodium polyacrylate, polyvinyl alcohol, and formaldehyde condensate; wherein a molecular weight of the vinylidene fluoride-chlorotrifluoroethylene copolymer is 200,000 g/mol to 600,000 g/mol; and wherein a decreased proportion of weight of the lithium adsorbent after 100 cycles of adsorption-washing-desorption is less than 0.1%.
2 . The lithium adsorbent according to claim 1 , wherein based on a weight of the lithium adsorbent, content of the adsorbing material is 80-95 wt %, content of the binder is 4-17 wt %, and content of the wetting and dispersing agent is 1-5 wt %.
3 . The lithium adsorbent according to claim 2 , wherein a ratio of a mass of the adsorbing material to a sum of a mass of the binder and a mass of the wetting and dispersing agent is greater than or equal to 8:1.
4 . The lithium adsorbent according to claim 2 , wherein a mass of the binder is 8%-12.5% of a mass of the adsorbing material.
5 . The lithium adsorbent according to claim 1 , wherein the wetting and dispersing agent comprises polyethylene glycol with a molecular weight of 10,000 g/mol to 30,000 g/mol.
6 . The lithium adsorbent according to claim 1 , wherein the lithium adsorbent has a porosity of 20%-45% and a pore size ranging from 1 nm to 100 nm.
7 . A method for lithium extraction from a salt lake, comprising: contacting a salt lake brine with a lithium adsorbent to perform a lithium adsorption process, and obtaining a lithium-rich adsorbent; and washing the lithium-rich adsorbent, performing a lithium desorption process with a desorbent, and obtaining a desorption solution, wherein the lithium adsorbent comprises an adsorbing material, a binder, and a wetting and dispersing agent, the binder comprises at least a vinylidene fluoride-chlorotrifluoroethylene copolymer, and the wetting and dispersing agent comprises one or more of polyethylene glycol, sodium polyacrylate, polyvinyl alcohol, and formaldehyde condensate; wherein a molecular weight of the vinylidene fluoride-chlorotrifluoroethylene copolymer is 200,000 g/mol to 600,000 g/mol; and wherein a decreased proportion of weight of the lithium adsorbent after 100 cycles of adsorption-washing-desorption is less than 0.1%.
8 . The method according to claim 7 , wherein the lithium adsorption process is performed with the salt lake brine having a flow rate of 1.5-3 BV/h for 2.5-4 h; and the lithium-rich adsorbent is washed for a plurality of times with a cleaning agent in a flow rate of 6-9 BV/h, and a total amount of the cleaning agent is no more than 2.5 BV.
9 . The method according to claim 7 , wherein a temperature of the desorbent is no more than 45° C. during the lithium desorption process.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based on and claims priority to and benefits of Chinese Patent Application No. 202111630402.6, filed on Dec. 28, 2021. The entire content of the above-referenced application is incorporated herein by reference. FIELD The present disclosure relates to the field of environmental protection and resource recycling, and specifically, to a lithium adsorbent and a method for lithium extraction from a salt lake. BACKGROUND In China, lithium resources are primarily stored in salt lake brines, mostly brines with high magnesium-to-lithium ratios. Therefore, lithium extraction from brines with high magnesium-to-lithium ratios becomes the focus of lithium resource development in China. The adsorption method developed in recent years has been widely favored due to its advantages of the good selectivity for lithium ions, simple process, the capability of extracting lithium from salt lake brines with high magnesium-to-lithium ratios, low cost, and the like. The key to the adsorption method is to develop lithium adsorbents with excellent performance. However, in the process of lithium extraction of the current adsorption method, the lithium adsorbent used is low in adsorption efficiency to lithium and high in self-dissolution loss rate, and the adsorbed lithium is not easy to be cleaned and desorbed while consuming a large amount of water and leading to high loss of lithium during cleaning. SUMMARY In view of this, the present disclosure provides a lithium adsorbent that can be used in a process of lithium extraction from a salt lake. By using at least one of a vinylidene fluoride-chlorotrifluoroethylene (VDF-CTFE) copolymer and a fluoroolefin-vinyl ether copolymer as a binder, with the cooperation of a specific wetting and dispersing agent, the lithium adsorbent is endowed with a good mechanical strength and a low dissolution loss rate, and the lithium adsorption efficiency is increased, the service life is improved, the water consumption in the process of washing and lithium desorption of the adsorbent is reduced, the temperature of lithium desorption is reduced, and a desorption solution with a low magnesium-to-lithium ratio is obtained. In an embodiment, according to a first aspect of the present disclosure, a lithium adsorbent is provided, including an adsorbing material, a binder, and a wetting and dispersing agent. The binder includes at least one of a vinylidene fluoride-chlorotrifluoroethylene (VDF-CTFE for short) copolymer and a fluoroolefin-vinyl ether copolymer (also referred to as FEVE fluorocarbon resin). The wetting and dispersing agent includes one or more of polyethylene glycol, sodium polyacrylate, polyvinyl alcohol, and formaldehyde condensate. In an implementation of the present disclosure, the molecular weight of the vinylidene fluoride-chlorotrifluoroethylene (VDF-CTFE) copolymer or the fluoroolefin-vinyl ether copolymer may be 100,000-800,000. In some implementations of the present disclosure, the wetting and dispersing agent includes polyethylene glycol with a molecular weight of 10,000-30,000. In an implementation of the present disclosure, based on the weight of the lithium adsorbent, the content of the adsorbing material is 80-95 wt %, the content of the binder is 4-17 wt %, and the content of the wetting and dispersing agent is 1-5 wt %. In some implementations of the present disclosure, a ratio of a mass of the adsorbing material to a sum of a mass of the binder and a mass of the wetting and dispersing agent is greater than or equal to 8:1. According to a second aspect, the present disclosure provides a method for lithium extraction from a salt lake, including the following steps. A salt lake brine is contacted with the lithium adsorbent according to the first aspect of the present disclosure to carry out lithium adsorption, to obtain a lithium-rich adsorbent. The lithium-rich adsorbent is washed, and lithium desorption is carried out with a desorbent, to obtain a desorption solution. In some implementations of the present disclosure, the lithium adsorption process is carried out with the salt lake brine having a flow rate of 1.5-3 BV/h for 2.5-4 h. In an embodiment, the lithium adsorption process is performed with the salt lake brine having a flow rate of 1.5-3 BV/h for 2.5-4 h, the lithium-rich adsorbent is washed for a plurality of times with a cleaning agent in a flow rate of 6-9 BV/h, and a total amount of the cleaning agent is no more than 2.5 BV. A temperature of the desorbent is no more than 45° C. during the lithium desorption process. The method for lithium extraction from a salt lake provided in the present disclosure is performed by using the foregoing lithium adsorbent, so the lithium adsorption efficiency can be increased. The method for lithium extraction from a salt lake has the advantages of simple process flow, low water consumption, low energy consumption, and high lithium extraction yield, which is convenient for lar