# US 11,993,520 B2 · Method for preparing a high-purity hydrated nickel sulphate

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- Number: US 11,993,520 B2
- Document ID: US11993520B2
- Status: Granted
- Kind: B2
- Application number: 17/280,962
- Filed: 2019-09-26
- Published: 2021-11-18
- Granted: 2024-05-28
- Earliest claimed: 2018-09-27
- Assignees: iGo, Inc.
- Applicants: Igo Limited
- Inventors: Karel John Osten; Rossano Antonio Grassi; Arturo Gutierrez Clausdorff; Ryan Colin Harrison
- Web page: https://patentgrep.com/patent/US11993520B2

## CPC

- C01G 53/10: Sulfates
- C01G 53/01: Preparation or separation involving a liquid-liquid extraction, an adsorption or an ion-exchange
- C22B 3/26: by liquid-liquid extraction using organic compounds
- C22B 3/32: Carboxylic acids
- C22B 3/326: {Ramified chain carboxylic acids or derivatives thereof, e.g. "versatic" acids}
- C22B 3/42: by ion-exchange extraction
- C22B 23/0461: {by chemical methods}
- C22B 23/0476: {Separation of nickel from cobalt}
- C01P 2006/80: Compositional purity
- Y02P 10/20: Recycling
- 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
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method for recovering NiSO4.6H2O crystals from a nickel rich organic phase is provided. The method includes contacting a nickel rich organic phase with an aqueous strip solution of sufficient H2SO4 concentration to extract nickel from the organic phase and of sufficient Ni2+ concentration to precipitate NiSO4.6H2O crystals and form a nickel lean organic phase. Also provided are methods for recovering NiSO4.6H2O crystals that include preceding processing steps, including low temperature pressure oxidation (LTPOX) autoclaving of a nickel sulphide concentrate to afford a pregnant leach solution (PLS).

## Claims

### Claim 1

A method of recovering NiSO4.6H2O crystals from a nickel rich organic phase, the method including:
contacting a nickel rich organic phase with an aqueous strip solution of sufficient H2SO4 concentration to extract nickel from the organic phase and of sufficient Ni2+ concentration to precipitate NiSO4.6H2O crystals and form a nickel lean organic phase.

### Claim 2 (depends on 1)

The method of claim 1, further including separating the NiSO4.6H2O crystals from the nickel lean organic phase.

### Claim 3 (depends on 1)

The method of claim 1, wherein the strip solution has a H2SO4 concentration of 10-300 g/L.

### Claim 4 (depends on 1)

The method of claim 1, wherein the nickel rich organic phase includes a coordination complex of nickel and an organic extractant, wherein the organic extractant dissociates from the nickel in the presence of a sufficient concentration of H+ ions.

### Claim 5 (depends on 4)

The method of claim 4, wherein the organic extractant is selected from the group consisting of: organophosphorous acids, chelating oximes or hydroxyoximes, carboxylic acids, and high molecular weight amines.

### Claim 6 (depends on 4)

The method of claim 4, wherein the organic extractant is a branched carboxylic acid that has the structure:
wherein R1 and R2 are branched or straight chain unsubstituted alkyl groups, and R1 and R2 together consist of from 5 to 13 carbon atoms.

### Claim 7 (depends on 1)

The method of claim 1, wherein the method includes:
a nickel solvent extraction step including contacting an aqueous acidic nickel sulphate containing solution with an organic phase including an organic extractant to selectively extract nickel sulphate from the aqueous solution into the organic phase to form a nickel sulphate lean aqueous raffinate and the nickel rich organic phase; and
separating the raffinate and the nickel rich organic phase;
wherein the organic extractant is one or more branched carboxylic acids.

### Claim 8 (depends on 7)

The method of claim 7, wherein the method includes:
cobalt extraction of the nickel sulphate containing solution prior to nickel solvent extraction, wherein the cobalt extraction step includes an organic extractant that selectively extracts cobalt over nickel into an organic phase to form a cobalt-rich nickel-lean extractant stream and a cobalt-lean nickel-rich raffinate.

### Claim 9 (depends on 7)

The method of claim 7, wherein the nickel sulphate containing solution is a pregnant leach solution derived from the low temperature pressure oxidation of a nickel sulphide concentrate.

### Claim 10 (depends on 7)

The method of claim 7, wherein the nickel sulphate containing solution is a pregnant leach solution derived from the low temperature pressure oxidation of nickel sulphide concentrate, the sulphide concentrate containing more than 10% nickel.

### Claim 11 (depends on 1)

The method of claim 1, wherein the method includes:
a nickel solvent extraction step including contacting an aqueous solution including nickel sulphate and one or more metal impurities with an organic phase, the organic phase including one or more branched carboxylic acid extractants to selectively facilitate the extraction of nickel sulphate from aqueous solution into the organic phase and form the nickel rich organic phase.

### Claim 12 (depends on 1)

The method of claim 1, wherein the method includes:
a nickel solvent extraction step including contacting an aqueous nickel sulphate containing solution with an organic phase including an organic extractant to form the nickel rich organic phase, wherein the aqueous nickel sulphate containing solution is a pregnant leach solution (PLS) that is a cobalt-lean nickel-rich raffinate.

### Claim 13 (depends on 1)

The method of claim 1, wherein the NiSO4.6H2O crystals include: 5 ppm or less Fe and/or 5 ppm or less Mn and/or 5 ppm or less Cu and/or 60 ppm or less Co and/or 10 ppm or less Zn.

### Claim 14 (depends on 1)

The method of claim 1, wherein the strip solution has a Ni2+ concentration of 60 g/L or greater.

### Claim 15

A method for producing nickel sulphate, the method including the steps of:
a) providing a source of nickel sulphide concentrate;
b) repulping the nickel sulphide of step (a) concentrate;
c) fine grinding the nickel sulphide concentrate from step (b) to a P80 of 10 microns;
d) low temperature pressure oxidation (LTPOX) autoclaving of the nickel sulphide concentrate from step (c) to afford a pregnant leach solution (PLS), wherein the nickel sulphide concentrate contains more than 10% nickel;
e) neutralising the PLS of step (d) using one or more bases selected from the group including ammonium hydroxide, limestone, lime, calcrete, magnesia, magnesite and sodium hydroxide;
f) counter current decantation of the PLS from step (e) to separate solids from the slurry of the PLS;
g) neutralising the PLS from step (f) using one or more bases selected from the group including ammonium hydroxide, limestone, lime, calcrete, magnesia, magnesite and sodium hydroxide;
h) optionally clarifying the PLS from step (g);
i) extracting cobalt from the PLS of step (g) or step (h), wherein the cobalt extraction includes an organic extractant that selectively extracts cobalt over nickel into an organic phase to form a cobalt-rich nickel-lean extractant stream and a cobalt-lean nickel-rich raffinate;
j) extracting nickel from the cobalt-lean nickel-rich raffinate of step (i); wherein the nickel extraction includes contacting the cobalt-lean nickel-rich raffinate with an organic phase including an organic extractant to form a nickel-rich organic phase; and
k) direct crystallisation of the nickel-rich organic phase of step (j), wherein the direct crystallisation includes contacting the nickel-rich organic phase with an aqueous strip solution of sufficient H2SO4 concentration to extract nickel from the organic phase and of sufficient Ni2+ concentration to precipitate NiSO4.6H2O crystals and form a nickel-lean organic phase;
wherein the nickel sulphate is between 21 and 24% nickel and is in the form of nickel sulphate hexahydrate (NiSO4.6H2O).