Recycling process for isolating and recovering rare earth metals and nickel hydroxide from nickel metal hydride batteries

A hydrometallurgical process for recovering rare earth metals and nickel hydroxide from nickel metal hydride batteries, the process comprising:

• fracturing nickel metal hydride batteries into larger pieces and a granular powder,
• where the larger pieces comprise battery case pieces, nickel-plated steel metal pieces, plastic pieces, and battery separator pieces, and
• where the granular powder comprises nickel hydroxide, cobalt hydroxide, conductive carbon, potassium hydroxide, and a reversible hydrogen absorbing metal alloy comprising rare earth metals, nickel metal, and cobalt metal;
• coarse screening the larger pieces and the granular powder to produce a screened coarse powder and unscreened larger pieces;
• fine screening the coarse powder to produce a screened fine powder and unscreened remaining pieces;
• digesting the screened fine powder in acid at a pH from 1.8 to 4.2 to produce a digested material;
• filtering the digested material to remove undigested solids from an acidification filtrate liquid, where the undigested solids comprise conductive carbon;
• raising the pH of the acidification filtrate liquid to a pH from 4.7 to 6 with heating from 60 to 80 degrees Centigrade to precipitate rare earth metal oxides and form a rare earth metal oxide slurry;
• filtering the rare earth metal oxide slurry to recover a rare earth metal oxide powder and produce a rare earth metal isolation filtrate;
• raising the pH of the rare earth metal isolation filtrate to a pH greater than 6 with heating from 60 to 85 degrees Centigrade to precipitate nickel hydroxide and form a nickel hydroxide slurry;
• and
• filtering the nickel hydroxide slurry to recover nickel hydroxide and produce a nickel hydroxide isolation filtrate.