United States Patent [19]
Reynolds et al.
[11]
[45]
4,192,676
Mar. 11, 1980
[54] HIGH TEMPERATURE REDUCTION OF [56]
COPPER SALTS
[75] Inventors: James E. Reynolds, Golden; Wayne
C. Hazen, Denver; Duane N. Goens,
Golden, all of Colo.
[73] Assignee: Cyprus Metallurgical Processes
Corporation, Los Angeles, Calif.
References Cited
U.S. PATENT DOCUMENTS
1,671,003 5/1928 Bagsar 75/91
4,017,307 4/1977 Winterhager et al. 75/72
4,039,324 8/1977 Stephens, Jr. et al. 75/72
Primary Examiner-L. Dewayne Rutledge
Assistant Examiner-Peter K. Skiff
Attorney, Agent, or Firm-Sheridan, Ross, Fields &
McIntosh
[21] Appl. No.: 905,091
[51] Int. C1.2 C22B 15/00
[52] U.S. C1•..............: 75/72; 75/91
[58] Field of Search 75/72, 91, 26, 0.5 B,
75/40; 266/204
[22] Filed: May 11; 1978
[57] ABSTRACT
Copper is recovered from copper salts selected from the
group consisting ofcopper chlorides, copper oxides and
copper oxychlorides by reducing the fmely divided
solid copper salts with hydrogen under turbulent conditions
at a temperature greater than the melting point of
elemental copper.
30 Claims, No Drawings
______________411
DESCRIPTION OF THE PREFERRED
EMBODIMENTS
2
reactor temperature is such that these chlorides flash
vaporize immediately. It is necessary to contact this
vapor immediately with hydrogen, resulting in an instantaneous
reaction, followed by processing to collect
5 the reduced fumes. This is preferably accomplished by
creating a cyclonic effect in the reactor, thereby coalescing
the fumes as liquid elemental copper. Other fume
collection techniques may be employed in lieu of or in
combination with this cyclone technique.
The process of the present invention is useful in the
recovery of elemental copper from various copper salts,
including copper oxides, copper chlorides and copper
oxychlorides. It is particularly useful for the reduction
of copper values which tend to agglomerate or sinter
upon reduction conditions taught in the prior art. These
copper values include to some degree copper oxides,
and particularly include cupric chloride and cuprous
chloride.
The copper bearing material must be introduced into
the reaction chamber as a finely divided solid. The
melting point of copper oxide is above 2000· C., and
therefore when processing this compound and when the
reaction temperature is less than its melting point, copper
oxide is easily introduced in solid form. Cupric
chloride at the required reaction temperature reduces to
cuprous chloride. Cuprous chloride has a melting point
of about 430· C., and has a relatively high vapor pressure
at the reaction temperature. This compo~nd therefore
immediately flash vaporizes when injected into a
reaction vessel having a temperature in excess of 1083·
C. The copper oxychloride mechanism is somewhat
more complex and most probably will behave either as
copper oxide as a result of its decomposition to this
compound, or as a copper chloride as a result of immediate
vaporization.
When dealing with feed components having a melting
point less than the reaction temperature, it is necessary
to maintain the feed in solid form until it is injected
into the reaction vessel. This may be accomplished, for
example, by injecting the feed through a water-cooled
or insulated injector nozzle. If necessary the injector
nozzle may extend into the reaction vessel. Other techniques
which would maintain the feed in solid form
until it is in the reaction vessel may also be employed.
A necessary element of the invention, in order to
50 insure a substantially instantaneous reduction reaction
as hereinafter discussed, is the introduction into the
reactor of the feed in relatively small particle size. The
maximum size limitation is dependent upon reactor
design, feed composition, reaction temperature and
other variables. Preferably the feed is sized at less than
about 500 microns, and more preferably less than about
100 microns.
The amount of hydrogen gas employed is in accordance
with stoichiometric requirements. An excess
amount of hydrogen is usually employed, although
under the preferred reaction conditions the reaction is
quite efficient and hence the excess generally need not
be too great. .
The actual reduction of the copper bearing materials
can occur at a temperature as low as 200· C. However,
in the present process, the reduction reaction must be
carried out at a temperature ofat least about 1083· C, and
preferably not in excess of about 1400· C. More prefera-
4,192,676
1
SUMMARY OF THE INVENTION
BACKGROUND OF THE INVENTION
Copper salts selected from the group consisting of
copper chlorides, copper oxides and copper oxychlorides
are reduced to elemental copper by injecting the 55
copper salts into a reactor in solid particulate form and
reducing these salts with hydrogen under turbulent
conditions at a temperature greater than the melting
point of copper. The reaction conditions must be such
as to allow the copper bearing material to be intimately 60
contacted with the hydrogen gas essentially at the moment
it is fed into the reactor so as to cause an essentially
instantaneous reaction with the hydrogen gas.
At the temperature of this process, copper oxides are
reduced as solids essentially instantaneously upon their 65
injection into the reactor. The resulting elemental copper
collects as a liquid and is recovered. Copper chlorides
are injected into the reactor in solid form, and the
HIGH TEMPERATURE REDUCfION OF COPPER
SALTS
1. Field of the Invention
This invention is concerned with a process of recovering
copper from various copper salts by means of
hydrogen reduction at temperatures exceeding the
melting point of copper. 10
2. The Prior Art
Many processes have been taught for the hydrogen
reduction of metallic salts to recover the elemental
metal. For example, U.S. Pat. No. 2,111,661 to Ebner
discloses the passing of finely divided molten magne- 15
sium chloride through a reaction chamber of hydrogen
gas at a temperature of 1200· C. to 1500· C. in order to
reduce the magnesium chloride to magnesium. Thereafter,
the magnesium is recovered by condensation.'
Several techniques deal specifically with copper salts. 20
Baghdasarian in U.S. Pat. No. 1,671,003 discloses chlorinating
metallic sulfides attemperatures in the range of
900· to 1200· C. to their corresponding metallic chlorides,
and then reducing the metallic chlorides with
hydrogen to produce the elemental metal and hydrogen 25
chloride. The preferred temperature disclosed for reducing
lead chloride with hydrogen is in excess of 800·
C.; whereas, a lower temperature is taught to be preferable
for the reduction of copper chlorides.
Additionally, a cyclone reaction chamber has been 30
used in a smelting process for impure copper concentrates.
"The KIVCET Cyclone Smelting Process for
Impure Copper Concentrates" Journal ofMetals, July,
1976, page 4, teaches the oxidation and slagging of the
copper in a cyclone with the reduction ofcopper occur- 35
ring in the settling hearth at temperatures ofabol1t 1350·
to 1400· C.
Many of these processes have problems with the
reduced copper agglomerating and sintering. U.S. Pat.
No. 4,039,324 to Stephens, Jr. et al circumvents this 40
problem by reducing the copper salts with hydrogen at
a temperature of from about 200· to about WOO· C. in a
fluidized bed in the presence of chemically inert, generally
spherical, relatively smooth, non-porous particles.
However, none of the prior art teaches the hydrogen 45
reduction of solid copper bearing material at a temperature
greater than the melting point of copper under
conditions which result in substantially instantaneous
copper reduction coupled with efficient fume collection.
_____________4111
4
EXAMPLES
EXAMPLE II
EXAMPLE III
Nitrogen gas and argon gas in amounts of 40 standard
cubic feet per hour (1.1 cubic meters per hour) and 3
standard cubic feet per hour (0.1 cubic meters per hour),
respectively, was used to carry 335 grams of cuprous
chloride sized to 100 microns into a water-cooled gun
which fed the cuprous chloride axially into a cyclone
reactor at a rate of 0.2 kilograms per hour. Hydrogen
gas was fed tangentially into the cyclone reactor at a
rate of 8 standard cubic feet per hour (0.2 cubic meters
per hour). The reduction reaction temperature was
about 10930 C. and the residence time in the reactor was
0.5 seconds. This resulted in 98.6% of the copper in the
feed material being reduced.
EXAMPLE IV
Recrystallized cuprous chloride was sized to 100
microns and 1.05 kilograms was fed through a watercooled
feed gun axially into a cyclone reactor at a rate
of 0.7 kilograms per hour. The cuprous chloride was
carried by an inert gas consisting of nitrogen and argon
in amounts of 40 standard cubic feet per hour (1.1 cubic
meters per hour) and 3 standard cubic feet per hour (0.1
cubic meters per hour), respectively. Hydrogen was fed
tangentially into the cyclone reactor at a rate of 8 standard
cubic feet per hour (0.2 cubic meters per hour).
The reduction reaction was carried out at a temperature
of 10850 C. and the gases were retained in the reactor
chamber for 0.5 seconds. This resulted in 89.9% of the
copper being reduced from the feed material.
What is claimed is:
EXAMPLE I
Nitrogen gas was used at a rate of 20 standard cubic
feet per hour (0.6 cubic meters per hour) to carry 454
grams of cuprous oxide and 265 grams of cupric oxide
into the vortex of a cyclone reactor at a rate of 0.6 and
0.5 kilograms per hour, respectively. Hydrogen gas was
fed tangentially into the cyclone reactor at a rate of 7
standard cubic feet per hour (0.2 cubic meters per hour).
The reduction reaction, which was carried out at a
temperature of about 11300 C. with the gases being
retained in the reactor chamber for 0.9 seconds, resulted
in 94.9% of the copper present in the feed being reduced.
All examples were carred out in a cylindrically
shaped graphite reactor having a diameter of two and
5 one-half inches.
4,192,676
3
bly the reaction temperature is maintained from about
11000 C. to about 13000 c., and most preferably from
about 1100' C. to about 12000 C.
The essence of the invention is to effect a high degree
of copper reduction substantially instantaneously upon
introduction of the copper feed into the reactor. The
preferred residence time in the reactor of the copper
feed and resulting reduced copper is less than about 10
seconds, more preferably less than about 3 seconds, and 10
most preferably less than about 1 second.
The reactor capacity is limited by the ability to maintain
the necessary reaction temperature. Since the reaction
is endothermic, much of the heat required must be
supplied through the reactor walls, by means ofconvec- 15
tion and radiation at the surface of the interior wall.
Hence, the capacity is controlled by the reactor design,
and the preferred designs maximize wall surface area
per volume of the reactor.
In order to accomplish such an instantaneous reac- 20
tion, the copper feed materials must immediately be
subjected to the hydrogen. Hence the respective inlets Two hundred and eighty five grams of cuprous chlofor
the copper feed and the hydrogen should be such as ride, sized to 100 microns carried by nitrogen gas at a
to bring the two reactants into contact as soon as the rate of21 standard cubic feet per hour (0.6 cubic meters
copper salts enter the reactor. Under properly con- 25 per hour) and argon gas at a rate of 3 standard cubic feet
trolled injection techniques the hydrogen may serve as (0.1 cubic meters per hour) per hour was fed through a
the carrier gas for the solid copper feed, but care must water-cooled gun axially into a cyclone reactor. Hydrobe
taken to avoid excessive reduction of copper prior to gen gas was fed tangentially into the cyclone reactor at
entering the reactor in order to prevent fouling of the a rate of 8 standard cubic feet per hour (0.2 cubic meters
injection lines. When hydrogen is injected separately 30 per hour). The reduction reaction occurred at a temperfrom
the copper feed, it is preferred to inject the copper ature of about 11000 C. and the gases had a residence
feed by means of an inert gas carrier. Examples of such time in the reaction chamber of0.7 seconds. The copper
gases include neutral combustion gases, nitrogen, argon chloride was fed into the reactor at a rate of 0.4 kiloand
helium. 35 grams per hour with 92.8% of the copper in the feed
Due to the instantaneous aspect of the invention, the material being reduced.
flow conditions in the reactor must be quite turbulent in
order to allow for the rapid and intimate contact between
the copper bearing material, whether it be in
solid or vapor form, and the hydrogen. Such turbulent 40
conditions also aid in the necessary heat transfer in
order to maintain the required reaction temperature.
The reduced copper particles immediately resulting
from the reaction are generally of the near sub-micron
size, and in accordance with the reaction temperature 45
the particles are in liquid form. The collection of such
particles is preferably accomplished as much as possible
within the reactor. A preferred technique is the utilization
of a cyclone flow pattern within the reactor. Such
a pattern permits the small particles to collect and co- 50
alesce into sufficiently large liquid particles in order to
facilitate the copper recovery.
Such a cyclone is preferably created by injecting a
gas tangentially into a cylindrically shaped reactor. The 55
inlet gas velocity is dependent upon reactor design, and
is generally from about 9 to about 27 meters per second,
and preferably from about 17 to about 22 meters per
second. The gas may be hydrogen or a gas inert to the
system. When this cyclone technique is employed, the 60
copper feed is preferably injected into the vortex of the
cyclone or parallel thereto.
Other collection techniques may be employed in lieu
of or in combination with this cyclone technique. Such
techniques include gravity settling in large chambers, 65
wet scrubbing, with collection of the copper as a powder
cake, dry fabric filtering, and other known fine
particle collection techniques.
....'"
~--------------------------
15
35
4;192,676
6
recovering the liquid elemental copper.
15. The process of claim 14 wherein the hydrogen is
injected tlU).gentially into the reactor at a velocity of
from'about 9 to about 27 meters per second.
16;'The process of Claim 14 wherein the copper bearing
material reacts within one second with the hydrogen
gas to form elemental copper.
17. The process of claim 14 wherein the copper bearing
material is a copper chloride.
18. The process of claim 17 wherein the copper chloride
is introduced into the reactor at a rate which allows
it to be flash vaporized and reacted substantially instantaneously
with the hydrogen gas to form elemental
copper.
19. A process for recovering elemental copper from
solid copper bearing materials selected from the group
of copper chlorides consisting of copper chlorides and
copper oxychlorides, which comprises:
finely dividing the copper bearing materials to a particle
size of less than about 500 microns;
maintaining the temperature of a reaction chamber
above the temperature of the melting point of copper;
injecting hydrogen gas into the reactor at a sufficient
velocity and angle to create turbulent conditions
within the reactor;
injecting the copper bearing material into the reactor
at a rate which allows it to be reacted substantially
instantaneously with the hydrogen gas; and
recovering molten copper from the bottom of the
reactor and copper particles from the gas stream.
20. The process of claim 19 wherein the' reactor is
maintained at a temperature of from about 1100· C. to
about 1200· C.
21. The process of claim 19 wherein the copper bearing
material is a copper chloride.
22. The process of claim 21 wherein the copper chloride
is selected from the group consisting of cupric
chloride and cuprous chloride.
23. The process of claim 22 wherein the copper chloride
is cuprous chloride.
24. The process of claim 23 wherein the cuprous
chloride is injected into the reactor under conditions
which allow it to be flash vaporized and reacted essentially
instantaneously with the hydrogen gas.
25. The process of claim 19 wherein the reactor is a
cyclone reactor.
26. The process of claim· 19 wherein the hydrogen
and copper bearing material are injected together into
50 the cyclone reactor.
27. The process ofclaim 24 wherein the hydrogen gas
is injected at a velocity of from about 9 to about 27
meters per second.
28. A process for reducing cuprous chloride with
hydrogen to elemental copper which comprises:
sizing the cuprous chloride to less than about 100
microns;
injecting the solid cuprous chloride into a cyclone
reactor whose interior walls are maintained at a
temperature of from about 1100· C. to about 1200·
C., thereby immediately flash vaporizing the cuprous
chloride;
injecting hydrogen gas tangentially into the reactor at
a velocity of from about 9 to about 27 meters per
second in order to create and maintain the cyclone
and permit a substantially instantaneous reaction •
with the cuprous chloride to form elemental copper;
5
1. A process for reducing copper bearing materials
selected from the group consisting of copper chlorides
and copper oxychlorides to elemental copper with hydrogen
which comprises:
injecting the copper bearing materials into a reactor 5
in finely divided solid form;
maintaining the reactor temperature in excess of
1083· C.;
contacting the copper bearing materials with hydrogen
under conditions which require intimate 10
contact and a substantially instantaneous reduction
reaction in order to produce liquid elemental copper.
2. The process of claim 1 wherein the copper bearing
material is a copper chloride.
3. The process ofclaim 2 wherein the copper chloride
is selected from the group consisting of cuprous chloride
and cupric chloride.
4. The process of claim 3 wherein the copper chloride
is cuprous chloride. 20
5. The process of claim 3 or 4 wherein the copper
chloride is immediately vaporized upon entering the
reactor.
6. The process of claim 1 wherein the copper bearing
materials are finely divided to a particle size ofless than 25
500 microns prior to being injected into the reactor.
7. The process of claim 1 wherein the reduction reaction
occurs within one second of the injection of the
copper bearing material into the reactor.
8. The process of claim 1 wherein the reaction occurs 30
in a cyclone.
9. A process for reducing copper chloride with hydrogen
to elemental copper comprising:
injecting the copper chloride into a reactor in finely
divided solid form;
maintaining the temperature of the reactor at greater
than 1083· C. in order to cause the immediate flash
vaporization of the copper chloride upon entering
the reactor; and
intimately contacting the copper chloride with hy- 40
drogen in order to substantially instantaneously
reduce the copper chloride to liquid elemental
copper.
10. The process of claim 9 wherein the reactor is
maintained at a temperature of from about 1100· C. to 45
about 1300· C.
11. The process of claim 9 wherein the substantially
instantaneous reduction reaction occurs within one
second of the injection of the copper bearing material
into the reactor.
12. The process of claim 9 wherein the reaction occurs
in a cyclone.
13. The process of claim 9 wherein the copper bearing
material is cuprous chloride.
14. A process for recovering elemental copper from 55
copper bearing materials selected from the group consisting
of, copper chlorides and copper oxychlorides
which comprises:
maintaining the temperature of the interior walls of a
reactor at a temperature of from about 1083· C. to 60
about 1400· C.;
introducing a gas into the reactor at a sufficient velocity
and angle to create a cyclone within the reactor;
introducing the copper bearing material as a finely
divided solid and hydrogen into the reactor under 65
conditions which cause a substantially instantaneously
reduction reaction to form elemental copper;
and
4,192,676
7
coalescing at least a portion of the elemental copper
within the cyclone; and
recovering molten copper from the bottom of the
reactor and copper particles from the gas stream. S
29. The process of claim 28 wherein the hydrogen is
10
IS
20
2S
30
3S
40
4S
so
SS
60
6S
8
injected at a velocity of from about 17 to about 22 meters
per second.
30. The process of claim 28 wherein the substantially
instantaneous reaction between the cuprous chloride
and hydrogen occurs within one second.
* * * * *