CA2525625A1 - Process and apparatus for producing pure nickel and cobalt from ores thereof - Google Patents

Abstract

A process for the production of pure metallic nickel and cobalt from metallic ores comprising oxides of nickel, cobalt and iron, the process comprising (a) treating the ores with hydrogen at a pressure of at least atmospheric pressure and an effective temperature, in the presence of chloride anion or an in situ generator thereof precursor; to produce a first mixture comprising particulate nickel and particulate cobalt; (b) reacting the first mixture with carbon monoxide to produce gaseous nickel carbonyl and a first residue comprising solid cobalt carbonyl; (c) removing and thermally decomposing the nickel carbonyl to produce the pure metallic nickel; (d) treating the first residue with an effective amount of a complexing gaseous mixture of nitric oxide and carbon monoxide to produce cobalt nitrosyl tricarbonyl;
and removing and decomposing the cobalt nitrosyl tricarbonyl to provide the purified cobalt and regenerated complexing gaseous mixture; and removing the regenerated complexing gaseous mixture.

Description

PROCESS AND APPARATUS FOR PRODUCING PURE
NICKEL AND COBALT FROM ORES THEREOF

This invention relates to apparatus and processes for producing pure nickel and pure cobalt from ores, minerals, scrap, slag concentrates, metallurgical intermediates and by-products comprising oxides of nickel, cobalt and iron.
BACKGROUND OF THE INVENTION

Canadian Patent No. 2,461,624, published 27 September 2004, and granted to Chemical Vapour Metal Refining Inc. describes a process for producing nickel carbonyl from carbon monoxide and a source of nickel selected from the group consisting of elemental nickel, a nickel compound or mixtures thereof, provided the nickel compound is not nickel chloride ~er se or in admixture with a nickel carbonate ore, in an amount greater than 50%
W/W nickel chloride; which process comprises (a) treating the nickel source with hydrogen at a pressure of at least atmospheric pressure and an effective temperature, in the presence of chloride anion or an in situ generator thereof precursor, to produce a resultant nickel; (b) reacting the carbon monoxide with the resultant nickel to produce the nickel carbonyl; and collecting the nickel carbonyl. The process offers the production of nickel carbonyl at atmospheric pressure and at a sufficiently high rate for direct use in subsequent deposition processes without the need for storage facilities.
United States Patent No. 6,428,601 B2 granted to Chemical Vapour Metal Refining Inc. on August 6, 2002 describes a process for producing purified cobalt from a mixture comprising metallic species of cobalt and metallic species of at least one of the group consisting of nickel and iron, comprising producing a metal carbonyl mixture of cobalt carbonyl and at least one of nickel carbonyl and iron carbonyl from the metallic species mixture; separating the nickel carbonyl and/or iron carbonyl from the cobalt carbonyl;
treating the cobalt carbonyl with an effective amount of a complexing gaseous mixture of nitric oxide/carbon monoxide to produce cobalt nitrosyl tricarbonyl; and decomposing the purified cobalt nitrosyl carbonyl to provide purified cobalt and regenerated complexing gaseous mixture for recycle. The process provides cobalt of improved quality in an optionally, Continuous and closed-loop manner. Preferred processes include either aqueous and/or gaseous process steps.
It well-known that metals such as, for example, nickel and iron can be recovered from reduced metal-containing mixtures, using carbonylation processes. Volatile nickel and iron carbonyls are formed at elevated temperatures and pressures, separated, isolated and thermally decomposed to yield pure metal pellets and carbon monoxide gas. The purity of the nickel metal produced by this process is extremely high because of the selectivity of the carbonylation reaction and the fact that other metals, often present with nickel, are either easily separated, or do not form gaseous compounds. However, in contrast, iron carbonyl cannot be completely separated from nickel carbonyl because these compounds form an inseparable isotropic mixture.
It has been reported that cobalt, which is often present with nickel and iron in metal-containing mixtures, such as ores and tailings, together forms a cobalt carbonyl under similar conditions particularly, when hydrogen is used, together with carbon monoxide for the formation of carbonyls. Cobalt carbonyl, having much lower vapour pressure than nickel and iron carbonyls, usually remains in the carbonyl reactor together with solid leftovers of the carbonylation reaction, or is partially carried, together with volatile carbonyls, and left as a solid residue after nickel and iron carbonyls' fractional separation. The further isolation of cobalt usually involves desolution of cobalt in acid, followed by electrowinning.
Similarly, carbonylation of inetals-containing mixture as in alkaline solution leads to the formation of gaseous nickel carbonyl as well as iron and cobalt carbonyl compounds that remain the solution. A further refining of cobalt involves an acidification of the solution, followed by cobalt organic solvent extraction. The extracted cobalt is then purified by electrowinning.
There have been several attempts to achieve cobalt extraction using volatile cobalt carbonyl precursors such as cobalt hydrocarbonyl. For example, when a slurry of cobalt, nickel and copper metals were treated with a carbon monoxide-hydrogen gas mixture at 68 bar pressure, mixtures of nickel carbonyl and cobalt carbonyl anions were produced. Volatile nickel carbonyl was degassed from the solution and the residue was filtered out. The basic solution of cobalt carbonyl salt was acidified with strong acid and volatile cobalt hydrocarbonyl boiled and removed from solution. Subsequent decomposition of cobalt

2 hydrocarbonyl resulted in a pure cobalt metal containing 30 ppm of Ni, 0.4 ppm of Fe and 0.1 ppm of copper. This procedure involves several handling processes, including filtration of the solution, dilution and acidification of the resulting solution.
Other separations of cobalt carbonyl from nickel carbonyl involved addition of ammonia to precipitate {Co(NH3)61[C0(CO)412, or cobalt removal by passage through ethanolic KOH.
It is known that iron nitrosyl carbonyl Fe(NO)2 (CO)2 has been prepared in the gaseous state by the reaction of NO with FE(CO)5 at 95 C., and in aqueous alkaline solution.
Further, CoNO(CO)3 can be beneficiously and efficaciously distilled from Fe-containing carbonyl species to provide Fe-free CoNO(CO)3 gas for subsequent decomposition to pure cobalt metal (99.8%).
Although H2 has been used as a reductant of metal oxide materials for subsequent reaction with carbon monoxide to form the metal carbonyl in the case of cobalt, inactive cobalt sulfide is produced.
Thus, there is a need for an improved method of providing metallic cobalt in a suitable form for subsequent efficacious conversion with carbon monoxide to cobalt carbonyl in the presence of other metals such as, for example, nickel and iron, initially present also as respective metal oxides.

SUMMARY OF THE INVENTION

Surprisingly, we have discovered that the reduction of cobalt oxide with hydrogen in the presence of chloride anion and impure oxides of nickel, iron and other metals, provides a mixture comprising metallic cobalt which is able to efficaciously react with carbon monoxide to form solid cobalt carbonyl, notwithstanding the presence of the other metallic and non-metallic entities in the ore. This discovery provides for the production of pure metallic cobalt by subsequent known process steps.
Accordingly, in one aspect the invention provides a process for the production of pure metallic nickel and cobalt from an ore comprising oxides of nickel, cobalt and iron, said process comprising

3 (a) treating said ores with hydrogen at a pressure of at least atmospheric pressure and an effective temperature, in the presence of chloride anion or an in situ generator thereof precursor; to produce a first mixture comprising particulate nickel and particulate cobalt;
(b) reacting said first mixture with carbon monoxide to produce gaseous nickel carbonyl and a first residue comprising solid cobalt carbonyl;
(c) removing said nickel carbonyl;
(d) thermally decomposing said nickel carbonyl to produce said pure metallic nickel;
(e) treating said first residue with an effective amount of a complexing gaseous mixture of nitric oxide and carbon monoxide to produce cobalt nitrosyl tricarbonyl;
(f) decomposing said cobalt nitrosyl tricarbonyl to provide said pure metallic cobalt and regenerated complexing gaseous mixture; and (g) removing said regenerated complexing gaseous mixture.
The term "ore" in this specification and claims includes , but is not restricted to heavy metal ores, minerals, scrap metal, slag concentrates, metallurgical intermediates and by-products.
Preferably, the chloride ion is present from a compound selected from hydrogen chloride and a metal chloride, and preferably the metal chloride is selected from the group consisting of an alkali, alkaline earth and transition metal chloride, particularly nickel chloride. The chloride anion is preferably present as gaseous hydrochloric acid in gaseous admixture with said hydrogen. Preferably, the gaseous admixture comprises HC1 and H2 in the molar ratio of about 1:2.
Preferably, the ore is first treated with hydrogen at the effective temperature for a first period of time and subsequently treated with the gaseous admixture for a second period of time, at said effective temperature.
The effective temperature is preferably selected from the range 300 - 650 C, and more preferably selected from 350 - 550 C.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In order that the invention may be better understood, preferred embodiments will now be described by way of example only with reference to the accompanying examples.

4 EXAMPLES
Example 1.
A mixture of reduce nickel and cobalt oxides comprised of nickel (54.5 g) and cobalt (5.5 g) was placed into a carbonylation reactor. The reactor was purged with nitrogen, all oxygen removed and the reactor pressurized with H2S (1.5 bar) for 15 minutes.
Following activation with H2S, carbon monoxide was introduced into the reactor at 10 bar and 85 C and nickel carbonyl removed from the reactor over a 5 hour period. Subsequently, after most of the nickel was removed, nitrogen oxide NO was introduced for 20 min. at 85 C
to remove formed cobalt carbonyl in the form of CoNO(CO)3. The reactor was subsequently purged with CO for 20 min and followed by a nitrogen purge. Residue (4.5 g) comprised of 73.6 %
Ni and 21.5% of Co remained in the reaction. Nickel yield 94% and Cobalt yield 82%.
Example 2.
A mixture of 90 g of NiC12 and 10 g of CoC12 was reduced with hydrogen at 450 C in a rotary reactor. The resulting mixture of reduced nickel and cobalt was treated with carbon monoxide at 50 C at atmospheric pressure whereupon the nickel reacted rapidly with carbon monoxide to produce nickel carbonyl gas which was removed from the reactor and decomposed at 175 C in a decomposition chamber, with CO recyle. After all of the nickel was removed, NO was introduced into the CO gas stream the form CoNO(CO)3 which was removed from the reactor to a second decomposition chamber. The cobalt nitrosocarbonyl was decomposed at 150 C and the resultant gas mixture recycled. After most of the cobalt was removed, the system was purged with nitrogen and nitrogen/oxygen mixture.
The residue (2.6 g) consisted 64.3 % nickel and 30.6 % of cobalt.

Example 3.
A mixture of 90 g of nickel oxide and 10 g cobalt oxide was reduced with a gaseous hydrogen/1%HC1 mixture at 450 C. Nickel extraction was carried out under the same conditions as for example followed by treatment with NO to extract cobalt.
Residue (2.8 g) consisted 63.8 % nickel and 31.1 % cobalt.
Example 4.
Ore sample (100 g) containing 2.2 % Ni, 12% Fe and 0.07% Co was heated in a reactor to 750 C to remove moisture. The temperature was reduced to 450 C and the reactor

5 purged with the gas followed by reduction of the sample with a H2/1% HCI
mixture over 4 hours. The reactor was cooled to 50 C and nickel and partially iron extracted in the form of metal carbonyls at atmospheric pressure using CO as a carrier gas. 5 hours extraction yielded

6.1 g of product (32% nickel and 68 % iron). Nitrogen oxide was introduced together with carbon monoxide to extract Co in the form of cobalt nitrosocarbonyl over 4 hours extraction to yield 60 mg of Cobalt.

Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to those particular embodiments. Rather, the invention includes all embodiments which are functional or mechanical equivalence of the specific embodiments and features that have been described and illustrated.

Claims (9)

Claims:

1. A process for the production of pure metallic nickel and cobalt from an ore comprising oxides of nickel, cobalt and iron, said process comprising (a) treating said ores with hydrogen at a pressure of at least atmospheric pressure and an effective temperature, in the presence of chloride anion or an in situ generator thereof precursor; to produce a first mixture comprising particulate nickel and particulate cobalt;
(b) reacting said first mixture with carbon monoxide to produce gaseous nickel carbonyl and a first residue comprising solid cobalt carbonyl;
(c) removing said nickel carbonyl;
(d) thermally decomposing said nickel carbonyl to produce said pure metallic nickel;
(e) treating said first residue with an effective amount of a complexing gaseous mixture of nitric oxide and carbon monoxide to produce cobalt nitrosyl tricarbonyl;
(f) decomposing said cobalt nitrosyl tricarbonyl to provide said pure metallic cobalt and regenerated complexing gaseous mixture; and (g) removing said regenerated complexing gaseous mixture.

2. A process as defined in claim 1 wherein said chloride ion is present from a compound selected from hydrogen chloride and a metallic chloride.

3. A process as defined in claim 2 wherein said metallic chloride is selected from the group consisting of an alkali, alkaline earth and transition metal chloride.

4. A process as defined in any one of claims 1 to 3 wherein said chloride anion is present as gaseous hydrochloric acid in gaseous admixture with said hydrogen.

A process as defined in any one of claims 1 to 4 wherein said ore is first treated with hydrogen at said effective temperature for a first period of time and subsequently treated with said gaseous admixture for a second period of time, at said effective temperature.

6. A process as defined in claim 4 or claim 5 wherein said gaseous admixture comprises HCl and H2 in the molar ratio of about 1:2.

7. A process as defined in any one of claims 1 to 6 wherein said chloride anion is present as nickel chloride.

8. A process as defined in any one of claims 1 to 7 wherein said effective temperature is selected from the range 300° - 650°C.

9. A process as defined in claim 8 wherein said effective temperature is selected from 350°-550°C.