# US 11,909,016 B2 · Recycling process for isolating and recovering rare earth metals and nickel hydroxide from nickel metal hydride batteries

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- Number: US 11,909,016 B2
- Document ID: US11909016B2
- Status: Granted
- Kind: B2
- Application number: 17/890,314
- Filed: 2022-08-18
- Published: 2023-10-19
- Granted: 2024-02-20
- Earliest claimed: 2021-08-24
- Assignees: American Hyperform, Inc.
- Applicants: American Hyperform, Inc.
- Inventors: William Novis Smith
- Web page: https://patentgrep.com/patent/US11909016B2

## CPC

- H01M 10/54: Reclaiming serviceable parts of waste accumulators
- C01G 53/05: Hydroxides; Oxyhydroxides
- C22B 3/08: Sulfuric acid {, other sulfurated acids or salts thereof}
- C22B 3/22: by physical processes, e.g. by filtration, by magnetic means {, or by thermal decomposition} (treatment or purification of solutions by liquid-liquid extraction C22B3/26)
- C22B 3/44: by chemical processes (treatment or purification of solutions by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42)
- C22B 7/007: {by acid leaching}
- C22B 59/00: Obtaining rare earth metals
- H01M 4/525: of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
- H01M 10/052: Li-accumulators
- H01M 2004/028: {Positive electrodes}
- Y02P 10/20: Recycling
- Y02W 30/84: Recycling of batteries or fuel cells
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanamide C01C3/16; thiocyanates C01C3/20)
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

A hydrometallurgical process is described that can isolate and recover NIMH battery constituents in high-value form: the nickel and cobalt hydroxides (cathode) as nickel and cobalt hydroxides; elemental nickel and cobalt (metallic anode) as nickel and cobalt hydroxides; rare earth metals (metallic anode) as oxides of rare earth metals, conductive carbon (electrodes) as conductive carbon, and the magnetic nickel-plated steel grids (electrodes) and battery cases in a relatively clean and directly smeltable form. The isolation portion of the process isolates the rare earth metals in oxide form from the nickel hydroxide and the cobalt hydroxide. If present, titanium, aluminum, and yttrium are isolated as oxides with the rare earth metal oxides.

## Claims

### Claim 1

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.

### Claim 2 (depends on 1)

The process of claim 1, where the coarse screening comprises screening with a 3- to 8-mesh screen.

### Claim 3 (depends on 2)

The process of claim 2, where the coarse screening further comprises slurrying the larger pieces and the granular powder in water before passing the larger pieces and the granular powder through the screen.

### Claim 4 (depends on 1)

The process of claim 1, further comprising washing the unscreened larger pieces with water to obtain additional coarse powder.

### Claim 5 (depends on 1)

The process of claim 1, where the fine screening comprises screening with a 40-mesh or less screen.

### Claim 6 (depends on 5)

The process of claim 5, further comprising washing the unscreened remaining pieces with water to obtain additional fine powder.

### Claim 7 (depends on 1)

The process of claim 1, further comprising smelting at least one of the unscreened larger pieces and the unscreened remaining pieces to produce ferronickel.

### Claim 8 (depends on 1)

The process of claim 1, further comprising subjecting the unscreened larger pieces and the unscreened remaining pieces to a magnetic separation, where the magnetic separation separates the battery case pieces and the nickel-plated steel metal pieces from the plastic pieces, and the battery separator pieces.

### Claim 9 (depends on 8)

The process of claim 8, further comprising smelting the battery case pieces and the nickel-plated steel metal pieces to produce ferronickel.

### Claim 10 (depends on 1)

The process of claim 1, further comprising passing a magnetic through the fine powder to recover additional magnet metal.

### Claim 11 (depends on 1)

The process of claim 1, where the acid is selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, formic acid, and combinations thereof.

### Claim 12 (depends on 1)

The process of claim 1, where the acid is sulfuric acid.

### Claim 13 (depends on 1)

The process of claim 1, where the digesting the screened fine powder in the acid is at a pH from 2 to 4.

### Claim 14 (depends on 1)

The process of claim 1, where the digesting does not significantly dissolve iron from the screened fine powder.

### Claim 15 (depends on 12)

The process of claim 12, where the digesting produces rare earth metal sulfates, nickel sulfate, and cobalt sulfate.

### Claim 16 (depends on 1)

The process of claim 1, where the raising the pH of the acidification filtrate liquid comprises adding an alkali-hydroxide aqueous base to the acidification filtrate liquid.

### Claim 17 (depends on 1)

The process of claim 1, where the filtering the rare earth metal oxide slurry is a small particle filtration, where the small particle filtration removes solids in a range 1 micrometer and larger.

### Claim 18 (depends on 17)

The process of claim 17, where the small particle filtration is performed using polypropylene filtration medium.

### Claim 19 (depends on 1)

The process of claim 1, where the undigested solids comprising conductive carbon are screened to isolate the conductive carbon.

### Claim 20 (depends on 19)

The process of claim 19, further comprising subjecting the isolated conductive carbon to magnetic separation to remove additional magnetic metal.

### Claim 21 (depends on 1)

The process of claim 1, further comprising adding an oxidant to the rare earth metal isolation filtrate to produce an iron precipitated slurry.

### Claim 22 (depends on 21)

The process of claim 21, where the base is an aqueous alkali-hydroxide base, and the oxidant is air.

### Claim 23 (depends on 21)

The process of claim 21, further comprising small particle filtering the iron precipitated slurry to recover precipitated ferric hydroxide.

### Claim 24 (depends on 1)

The process of claim 1, where the raising the pH of the acidification filtrate liquid to a pH from 4.7 to 6 raises the pH of the acidification filtrate liquid to a pH from 5 to 5.5.

### Claim 25 (depends on 1)

The process of claim 1, where the raising the pH of the rare earth metal isolation filtrate to a pH greater than 6 raises the pH of the rare earth metal isolation filtrate to a pH from 7 to 8.

### Claim 26 (depends on 25)

The process of claim 25, further comprising raising the pH of the nickel hydroxide isolation filtrate to a pH from 8.5 to 11 with heating from 60 to 85 degrees Centigrade to produce a cobalt hydroxide precipitated slurry.

### Claim 27 (depends on 26)

The process of claim 26, further comprising small particle filtering the cobalt hydroxide precipitated slurry to recover cobalt hydroxide.

### Claim 28 (depends on 1)

The process of claim 1, further comprising using the nickel hydroxide to form cathode materials for lithium batteries.

### Claim 29 (depends on 27)

The process of claim 27, further comprising using the cobalt hydroxide to form cathode materials for lithium batteries.