Method of concentrating lithium-containing solutions and recovering lithium therefrom

Patent metadata

Field	Value
Publication number	US-2022395780-A1
Application number	US-202217836088-A
Country	US
Kind code	A1
Filing date	Jun 9, 2022
Priority date	Jun 9, 2021
Publication date	Dec 15, 2022
Grant date	—

Abstract

A method of concentrating lithium containing solutions includes inputting a feed brine solution to an initial separation stage, the feed brine solution including lithium sulfate and one or more of sodium sulfate, potassium sulfate, calcium sulfate, and sodium chloride dissolved in water. In the initial separation stage, the feed brine solution is introduced to a pre-treatment membrane at a pressure that is less than the osmotic pressure of the feed brine solution. An initial permeate that passes through the pre-treatment membrane becomes the feed to a final separation stage, and an initial retentate that does not pass through the pre-treatment membrane includes a precipitate of at least one of the salts other than lithium sulfate. In the final separation stage, the initial permeate is introduced to a nanofiltration membrane at a pressure that is less than the osmotic pressure of the initial permeate. A final retentate that does not pass through the nanofiltration membrane is combined with the initial retentate to obtain a product solution having a higher concentration of dissolved lithium sulfate than the feed brine solution.

First claim

What is claimed is:

1 . A method of concentrating lithium containing solutions, the method comprising:
inputting a feed brine solution to an initial separation stage, the feed brine solution including lithium sulfate and one or more of sodium sulfate, potassium sulfate, calcium sulfate, and sodium chloride dissolved in water; the initial separation stage including the step of introducing the feed brine solution to a pre-treatment membrane at a pressure that is less than the osmotic pressure of the feed brine solution to obtain an initial permeate that passes through the pre-treatment membrane and an initial retentate that does not pass through the pre-treatment membrane, wherein a precipitate of at least one of the salts other than lithium sulfate is included in the initial retentate; directing the initial permeate to a final separation stage including at least one separation step, the at least one separation step including introducing the initial permeate to a nanofiltration membrane at a pressure that is less than the osmotic pressure of the initial permeate to obtain a final permeate that passes through the nanofiltration membrane and a final retentate that does not pass through the nanofiltration membrane, wherein a precipitate of at least one of the salts other than lithium sulfate is included in the final retentate; combining the initial retentate and the final retentate to obtain a retentate mixture; and separating the precipitated salts from the retentate mixture to obtain a product solution having a higher concentration of dissolved lithium sulfate than the feed brine solution.

2 . The method of claim 1 , wherein the final separation stage includes a first separation step and a second separation step;
the first separation step including introducing the initial permeate to a first nanofiltration membrane at a pressure that is less than the osmotic pressure of the initial permeate to obtain an intermediate permeate that passes through the first nanofiltration membrane and an intermediate retentate that does not pass through the first nanofiltration membrane, wherein a precipitate of at least one of the salts other than lithium sulfate is included in the intermediate retentate; and the second separation step including introducing the intermediate permeate to a second nanofiltration membrane at a pressure that is less than the osmotic pressure of the intermediate permeate to obtain the final permeate that passes through the second nanofiltration membrane and the final retentate that does not pass through the second nanofiltration membrane.

3 . The method of claim 2 , wherein the step of combining the initial retentate and the final retentate to obtain a retentate mixture further includes combining the intermediate retentate with the initial retentate and the final retentate to obtain the retentate mixture.

4 . The method of claim 1 , wherein the pre-treatment membrane in the initial separation stage is one of an ultrafiltration membrane and a loose nanofiltration membrane.

5 . The method of claim 4 , wherein the pre-treatment membrane is one of a tubular membrane and a wide feed channel spiral-wound membrane.

6 . The method of claim 4 , wherein the pre-treatment membrane is a tight ultrafiltration membrane having a molecular weight cut-off (MWCO) in the range of 1000 to 1500 Da.

7 . The method of claim 4 , wherein the pre-treatment membrane is an ultrafiltration membrane having a molecular weight cut-off (MWCO) in the range of 1500 to 4000 Da.

8 . The method of claim 4 , wherein the pre-treatment membrane is a loose nanofiltration membrane having a molecular weight cut-off (MWCO) in the range of 100 to 1000 Da.

9 . The method of claim 1 , wherein the nanofiltration membrane in the final separation stage is one of a spiral-wound membrane and a tubular membrane.

10 . The method of claim 9 , wherein the nanofiltration membrane is a wide feed channel spiral-wound nanofiltration membrane.

11 . The method of claim 9 , wherein the nanofiltration membrane has a molecular weight cut-off (MWCO) in the range of 100 to 450 Da.

12 . The method of claim 1 , wherein the pH of the feed brine solution in the initial separation stage is in the range of 1.5 to 11.

13 . The method of claim 1 , wherein the pH of one or more of the feed brine solution and the initial permeate is adjusted by adding sulfuric acid.

14 . The method of claim 1 , wherein the precipitate in the initial retentate includes calcium sulfate salt.

15 . The method of claim 1 , wherein the pressure in the initial separation stage and the final separation stage is in the range of 10 to 50 bar.

16 . The method of claim 1 , wherein lithium sulfate is present in the feed brine solution in an amount in the range of 1 to 2 wt. %, and in the product solution in an amount in the range of 8 to 10 wt. %.

17 . The method of claim 2 , wherein the final separation step further includes a reverse osmosis separation step after the second separation step, the reverse osmosis step including introducing the permeate from the second separation step to a reverse osmosis membrane to obtain a permeate that is substantially free of salt, and the retentate from the reverse osmosis step is further combined with the retentate mixture.

18 . A system for concentration and recovery of lithium containing solutions, the system comprising:
a feed of brine solution including lithium sulfate and one or more aqueous solutions of sodium sulfate, potassium sulfate, calcium sulfate, and sodium chloride; an initial separation stage including a pre-treatment membrane to which the brine solution is introduced via an input that receives the feed of brine solution at a pressure that is less than the osmotic pressure of the feed brine solution, an initial permeate outlet on the opposite side of the pre-treatment membrane relative to the feed, and an initial retentate outlet on the same side of the pre-treatment membrane as the feed, wherein an initial permeate that passes through the pre-treatment membrane exits the initial separation stage through the initial permeate outlet, and an initial retentate that does not pass through the pre-treatment membrane exits the initial separation stage through the initial retentate outlet, and a precipitate of at least one of the salts other than lithium sulfate is included in the initial retentate; a final separation stage including a nanofiltration membrane to which the initial permeate is introduced via an input that receives the initial permeate from the initial separation stage at a pressure that is less than the osmotic pressure of the initial permeate, a final permeate outlet on the opposite side of the nanofiltration membrane relative to the input of initial permeate, and a final retentate outlet on the same side of the membrane as the input of initial permeate, wherein a final permeate that passes through the nanofiltration membrane exits the final separation stage through the final permeate outlet, and a final retentate that does not pass through the nanofiltration membrane exits the final separation stage through the final retentate outlet, and a precipitate of at least one of the salts other than lithium sulfate is included in the final retentate; and a filtration stage connected to the initial retentate outlet and the final retentate outlet, the filtration stage including a filter that removes the precipitated salts from the initial retentate and the final retentate to obtain a product solution having a higher concentration of dissolved lithium sulfate than the feed br

Assignees

• Ut Battelle Llc

Inventors

• Bhave Ramesh R
• Islam Syed Z
• Wagh Priyesh A

Classifications

• B01D61/58 Primary

  Multistep processes · CPC title

• B01D2311/18

  pH control · CPC title

• B01D61/029

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

• B01D2311/14

  Pressure control · CPC title

• B01D61/145

  Ultrafiltration · CPC title