LITHIUM RECYCLING
A recycling method for generating purified lithium salts from a recycling stream of lithium-ion (Li-ion) batteries includes leaching black mass from the recycling stream in an aqueous solution of an oxidizing agent. Delithiated black mass is filtered from the aqueous solution to generate a Li-rich leach solution, which is subjected to nanofiltration to form a nanofiltration permeate from which the purified lithium salt is obtained.
1 . A method of generating a purified lithium salt from a recycling stream of lithium-ion (Li-ion) batteries comprising:
leaching black mass from the recycling stream in an aqueous solution of an oxidizing agent,
filtering delithiated black mass from the aqueous solution to generate a leach solution,
subjecting the leach solution to nanofiltration to form a nanofiltration permeate and a nanofiltration concentrate, and
obtaining the purified lithium salt from the nanofiltration permeate.
2 . The method of claim 1 , wherein the oxidizing agent is a persulfate or a chlorate oxidizing agent.
3 . The method of claim 1 wherein the oxidizing agent is an ammonium salt oxidizing agent.
4 . The method of claim 1 , wherein the oxidizing agent is ammonium persulfate (APS).
5 . The method of claim 1 , wherein the black mass is leached at a temperature of greater than 60° C. for 2-8 hours.
6 . The method of claim 1 , wherein the purified lithium salt is obtained by:
concentrating the nanofiltration permeate by reverse osmosis to form a concentrated Li solution,
combining the concentrated Li solution and a water-soluble salt to form a purified lithium salt solution, and
obtaining the purified lithium salt from the purified lithium salt solution.
7 . The method of claim 6 , wherein the water-soluble salt is a carbonate or a hydroxide.
8 . The method of claim 7 , wherein the water-soluble salt is sodium carbonate, sodium hydroxide, magnesium hydroxide, or calcium hydroxide.
9 . The method of claim 6 , wherein the purified lithium salt solution comprises at least 95% by weight of the purified lithium salt.
10 . The method of claim 6 , wherein, prior to concentrating the nanofiltration permeate by reverse osmosis, the nanofiltration permeate is purified using an ion exchange resin.
11 . The method of claim 10 , wherein the purified lithium salt solution comprises at least 99% by weight of the purified lithium salt.
12 . The method of claim 1 , wherein a nanofiltration membrane for nanofiltration is selected based on an ion selectivity of Li over ions introduced by the oxidizing agent.
13 . The method of claim 1 , wherein the black mass comprises Ni, Mn, and Co from NMC batteries in the recycling stream.
14 . The method of claim 1 further comprising determining moles of Li in the black mass and wherein the amount of the oxidizing agent is based on the determined moles of Li.
15 . The method of claim 14 , wherein the oxidizing agent is in a molar ratio of 0.45-0.7 to the moles of Li in the black mass.
16 . The method of claim 1 further comprising passing the filtered, delithiated black mass to an NMC recycling process.
17 . The method of claim 1 further comprising generating nickel sulfate from the nanofiltration concentrate.
18 . The method of claim 1 , wherein the leach solution is iteratively subjected to nanofiltration for concentrating the nanofiltration permeate.
19 . The method of claim 1 further comprising subjecting the leach solution to ultrafiltration to remove suspended submicron particles prior to nanofiltration.
20 . The method of claim 1 further comprising acidifying the leach solution to a pH of less than 4 for nanofiltration.