Method for concentrating and purifying eluate brine for the production of a purified lithium compound

Patent metadata

Field	Value
Publication number	US-12258280-B2
Application number	US-202017438495-A
Country	US
Kind code	B2
Filing date	Mar 9, 2020
Priority date	Mar 13, 2019
Publication date	Mar 25, 2025
Grant date	Mar 25, 2025

Abstract

A method is disclosed for concentrating and purifying an eluate brine and producing a purified lithium compound. An extraction eluate, rich in lithium, is directed to a nanofiltration unit or a softening process that removes sulfate and/or calcium and magnesium. Permeate from the nanofiltration unit or the effluent from the softening process is directed through an electrodialysis unit. As the lithium-rich solution moves through the electrodialysis unit, lithium, sodium and chloride ions pass from the solution through a cation-transfer membrane and an anion-transfer membrane to concentrate compartments. A dilute stream is directed through the concentrate compartments and collects the lithium, sodium and chloride ions. The electrodialysis unit also produces a product stream which contains non-ionized impurities, such as silica and/or boron. Concentrate from the electrodialysis unit is subject to a precipitation process that produces a lithium compound that is subsequently subjected to a purification process.

First claim

What is claimed is:

1. A method of recovering lithium carbonate from a brine rich in lithium, sodium and chloride and having impurities in the form of hardness, sulfate, and silica, the method comprising:
directing the brine to a nanofiltration unit and subjecting the brine to nanofiltration and removing sulfate from the brine, along with hardness associated with the sulfate;
wherein after nanofiltration, the brine still contains silica and residual hardness and remains rich in lithium, sodium and chloride;
after nanofiltration, maintaining conditions in the brine that result in the silica being substantially non-ionized;
further after nanofiltration, directing the brine through an electrodialysis unit and subjecting the brine to an electrodialysis process and producing a concentrate rich in lithium, sodium and chloride and a product stream depleted in lithium, sodium and chloride but including the substantially non-ionized silica;
after subjecting the brine to the electrodialysis process, directing the concentrate to an ion-exchange unit and removing residual hardness from the concentrate;
after removing residual hardness from the concentrate, directing the concentrate of lithium, sodium and chloride to a precipitating unit and mixing a selected reagent with the concentrate and precipitating lithium carbonate; and
recovering the precipitated lithium carbonate.

2. The method of claim 1 further including:
directing the product stream from the electrodialysis unit to a reverse osmosis unit and producing a permeate stream and a concentrate stream containing silica; and
utilizing the permeate stream in a lithium extraction process that take places upstream of the nanofiltration unit.

3. The method of claim 1 further including:
directing the concentrate from the electrodialysis unit to an evaporator or crystallizer and further concentrating the concentrate; and
thereafter directing the further concentrated concentrate to the ion exchange unit.

4. The method of claim 1 including mixing sodium carbonate with the concentrate rich in lithium, sodium and chloride and precipitating lithium carbonate.

5. The method of claim 1 wherein the electrodialysis unit comprises a feed compartment that produces the product stream and two concentrate compartments that produce the concentrate and which are disposed on opposite sides of the feed compartment; and wherein the concentrate compartments are separated from the feed compartment by a cation-transfer membrane and an anion-transfer membrane.

Assignees

• Veolia Water Solutions & Tech
• Mack Bernard Roy

Inventors

• Mack Bernard Roy

Classifications

• B01D61/422

  Electrodialysis · CPC title

• B01D61/029

  Multistep processes comprising different kinds of membrane processes selected from reverse osmosis, hyperfiltration or nanofiltration · CPC title

• B01D2311/2512

  to feed side · CPC title

• B01D2311/2523

  to feed side · CPC title

• C02F2001/5218

  Crystallization · CPC title