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

APPAREIL ET METHODE DE PRODUCTION DE COBALT ET DE NICKEL PURS A PARTIR DE MINERAIS

English 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.

Claims

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.
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Description

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PROCESS AND APPARATUS FOR PRODUCING PURE
NICKEL AND COBALT FROM ORES THEREOF
FIELD OF THE 1NVENTION
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
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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
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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
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(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.
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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
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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.
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