United States Patent
Kruesi et al.
[ 19] [II] 3,901,776
[45] Aug. 26, 1975
Primary Examiner-R. L. Andrews
A[(orney, ARent, or Firm-Sheridan, Ross & Fields
[54) PROCESS FOR THE RECOVERY OF
COPPER FROM ITS SULFIDE ORES
[75) Inventors: Paul R. Kruesi; Duane N. Goens,
both of Golden, Colo.
[73 J Assignee: Cyprus Metallurgical Processes
Corporation, Los Angeles, Calif.
[56]
from its sulfide ores or concentrates thereof which
comprises treating the ore with cupric chloride and/or
ferric chloride to form a copper chloride electrolyte
and a residue, electrolytically recovering copper from
the electrolyte and further treating the residue with
ferric chloride to solubilize substantially all of the copper
remaining therein for conversion to copper chloride
electrolyte, with ferrous chloride from the electrolyte
being regenerated to ferric chloride for leaching
the residue, the improvement which comprises
conducting the electrolysis without the conversion of
any cuprous copper to cupric copper, using a separator
between the anolyte and catholyte compartments
of the electrolytic cell to prevent passage of ions of
copper and iron between the catholyte and anolyte,
continuously further treating the residue with regenerated
ferric chloride of a concentration to insure there
is no cuprous copper in the resulting solution and regenerating
ferric chloride from ferrous chloride in the
solution free of cuprous chloride by passing the solution
through the anolyte compartment of the electrolytic
cell as copper is continuously being recovered at
the cathode of the cell.
Nov. 14, 1974
References Cited
UNITED STATES PATENTS
9/1973 Tirrell 204/107
10/1973 Hazen 204/1 07
Filed:
Appl. No.: 523,588
U.S. CI 204/107
Int. CI... C22d 1/16
Field of Search 204/1 07
3,761,369
3,767,543
[22J
[21 J
[52J
[51 J
[58)
RECYCLE CuO
10 Claims, 1 Drawing Figure
[57J ABSTRACT
An improvement in the process for recovering copper
FEED
IALTERNATE ~--I
I
~HYDRO;LYSIS I
IFe203
I FeCI3
I
I
FeCI
PROOUCT
Fe
PATENTED AUG 261975 3,901,776
I FEED I
I GRIND I
RECYCLE Cuo
I LEACH I I
FILTERS REDUCTION CATHOLYTEI
ITH ICKENERI I
I ~
I ANODES I ICATHODES I ~ LJ ILEACH 2 I :THICKENER~
I f
ITHICKENERI I ANODES I ICATHODES I CuO PRODUCT
LJ ~ ILEACH 3 I :THICKENER ~
I t
ITHICKENER~ I ANODES I ICATHODES I cIP
H2O l FILTERS ~ ITHICKENER r
cta
I TAILS
I
IALTERNATE ~--- PURIFICATION
I
Fe II
I
02 iHYDROLYSIS I IFe CELL CATHODES
II
Fe203
I FeCI3 IFe CE LL ANODES III
Fe CI 3
3,90 1,776
2
expcuient is to avoid the presence of ferric ions in the
anolyte hy leaving enough cuprous copper in the electrolyte
for oxidation to cupric copper to prevent any
oxidation of ferrous ion to ferric ion as the first oxida-
5 tion has precedence over the latter. This procedure
eliminates ferric ions in the electrolyte which might
travel to the cathode. but it also requires circulation of
the electrolyte from cathode to anode or some other
procedure to prevent cupric ions from coming in the
vicinity of the cathode. An objection to the latter procedure
is. of course. that large amounts of copper are
heing recirculated in a continuous process when only
a portion of the copper entering the cell is being recovcredo
In these procedures in which electrolysis is performed
on an electrolyte resulting from initially leaching
the copper sulfide ores with ferric chloride and/or
cupric chloride. the ferrous chloride entering the cell
in the electrolyte passes on through the cell unaffected
and is conventionally oxidized to ferric chloride in the
spent electrolyte and the resulting ferric chloride recirculated
to leach chalcopyrite residue from the initial
cupric chloride leaching step. Ordinarily. only one effective
leaching can be performed with the recirculated
25 ferric chloride without regeneration as it is suhstuntiully
reduced to ferrous chloride in the leaching of the
chalcopyrite residue. An efficient means utilizing the
electrolytic cell for regenerating the ferric chloride
after leaching the chalcopyrite residue for further
leaching of residue is desirous. In accordance with this
invention a process is provided hy which the anode of
the electrolytic cell is used to regenerate spent ferric
chloride from chalcopyrite residue leaching while copper
is being continuously recovered at the cathode in
the ahsence of ferric and cupric ions.
U.S. Pat. No. 333.X 15 discloses an electrolytic process
for the recovery of copper from ferric chloride
leach solutions of copper sulfide ores in which ferric
chloride is regenerated at the anode. However. this
process is performed with cuprous ions in the presence
of the anode and would olwiously be inefficient to re·
generate ferric chloride because of the precedence of
the oxidation of cuprous to cupric ions over the oxidation
of ferrous to ferric ions. Also. no procedure is provided
for preventing cupric and ferric ions from contacting
the cathode of preventing the conversion of cuprous
to cupric ions during the cell operation.
U.S. Pat. No. 3.767.543 discloses the regeneration of
ferric chloride from fermus chloride ,It the anode as
copper is heing electrolytically recovered at the cathode
from a ferric chloride leach solution of chalcopyrite.
However. since cuprous ions arc present in the anolyte
an inefficient regeneration of ferric chloride will
result. Further. no provision is made to prevent the
conversion of cuprous to cupric ions.
U.S. Pat. Nos. 3.764.4':lO und 3.776.H26 hoth disdose
the conversion of cuprous to cupric copper at the
anode lmd the processes of these patents arc not concerned
with the regencmtion of ferric chloride from
ferrous chloride ut all as ferric chloride is not used in
leaching the copper sulfide ores.
U.S. Pat. No. 3.7H5.':l44 discloses a process in which
copper in chalcopyrite is initially soluhilized hy treatment
with cupric chloride and/or ferric chloride with
ferric t:hloride being used to treat residue from the initial
treatment of the chalcopyrite ore concentrate. An
electrolyte is produced in a second reduction stage with
I
PROCESS FOR THE RECOVERY OF COPPER
I'ROM ITS SULFIDE ORES
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to hydrometallurgical processes
for recovering copper from its sulfide ores in
which the sulfide sulfur is recovered as elemental sulfur
so that the sulfur dioxide pollution prphlem characteristic
of pyrometallurgieal processes is eliminated. Par- 10
ticularly. the invention is related to those processes
wherein the copper in copper sulfide is soluhilized hy
treating the ore with cupric chloride and/or ferric chloride
with the copper heing recovered from thc resulting
copper chloride solution hy electrolysis. The present 15
process results in the recovery of high yields of commercial
grade copper with economic consumption of
power in the electrolysis step due to an improvement
hy which no cuprous copper is converted to cupric copper
during electrolysis and the anode of the cell is uti- 20
Iized for the conversion of ferrous chloride from spent
ferric chloride leach solution to ferric chloride for further
le,lching while suhstantially all of the copper is
heing continuously plated from the electrolyte.
2. Prior Art
As is well known. the main source for copper today
is copper sulfide ores. principally. chalcopyrite. Conventional
pyrometallurgical processes by which the
copper was formcrly recovered from its sulfide ores are
ohjectionahle today hecause of the polluting effect of 30
the sulfur dioxide produced by these processes. Accordingly.
there is a great deal of activity in the copper
industry to develop pollution-free processes for the rec(}
very of copper from its sulfide ores.
A large numher of hydrometallurgical processes are 35
heing developed in which the copper in its sulfide ores
is soluhilized hy treatment of the ore with ferric chloride
and/or cupric chloride with the formution of elemental
sulfur followed hy recovery of the copper from
the resulting solution or electrolyte by electrolysis. The 40
sulfur dioxide pollution prohlem is eliminated in these
processcs in which the sulfide sulfur is converted to elemental
sulfur.
The steps for soluhilizing copper in chalcopyrite usually
include the proccdure of first reacting the raw ore 45
with cupric chloride followed hy further reaction of the
resulting solution with a reducing agent such as metallic
copper to provide an electrolyte which is essentially
all cupruus chloride. Thc residue from the cupric chlo-
50 ride reaction step is then treated with ferric chloride to
soluhilizc essenti,llIy all of the remaining copper. In
order for these processes to he commercially feasihle.
they must be highly efficient in the consumption of
electrical energy. regeneration of reagents. removal of 55
impurities. recovcry of other mehlls contained in the
ore. and they must not generate undesimble amounts
of sulfate ions with the c()J1sequent prohibitive consumption
of elcctrical energy or reagents.
h is well known that for the economic recovery of nO
copper hy electrolysis the copper in the electrolyte
must be in the cuprous form. It is also well known that
the presence of ferric or cupric ions at the cllthode
where copper is heing plated fmm cuprous t:hloride interferes
with the pluting of the copper. An expedient ttl M
keep these ions awuy from the cathmle is the use of a
separator to prevent the circulation of electrolyte from
cathode tn anode as the pluting is in pmgress. Another
3
3,40 1,776
4
III
-- 4CuCI + FeCit + 2S 12 )
DESCRIPTION OF THE PREFERRED
EM80DIMENTS
The solids are separated as chalcopyrite residue and
the solution subjected to a reduction stage with recycled
copper from the electrolysis in which cupric chloride
is reduced to cuprous chloride in accordance with
the following reuction.
eu + CuClt -- 2CuCI
Referring to the flow diagram, feed of chalcopyrite
ore concentrate ground to an average particle size preferahly
l}(I(k - 200 mesh is subjected to a cupric chloride
leach in leach I. The leaching solution mayor may
not contain ferric chloride. The reactions between
chalcopyrite and ferric chloride and cupric chloride are
as follows:
4FeCI" + CuFeS, -- CuCI, + 5FeCI2 + 2S
The solution containing ferrous chloride and suhstantially
all of the copper as cuprous chloride is introduced
into the cathode compartment of an electrolytic cell for
recovery of copper. The ferrous chloride is not affected
by the electrolysis and passes on through the cell in the
spent electrolyte.
The electrolytic cell is provided with a separator hetween
the anode and cathode sepurating it into anolyte
and catholyte compartlllents. The separator used prevents
ions of copper and iron from travelling from the
cathode to the anode. The separator also prevents the
direct flow of catholyte to anolyte or vice versa. An example
of a suitahle memhrane is a microporous poly-
35 propylene film sold under the trademark "CELGARD"
by the Celanese Plastics Company, Newark, N.J.
The electrolyte is about 2.5 molar in ferrous chloride
at a pH of 0.5. A cell temperature of about XO°C is
used. An anode current density of ahout ~0-120 amps
40 per sq. ft. and a cathode current density of about
50-100 amps per sq. ft. are used. Some of the copper
recovered at the cathode is recycled to the reduction
stage for reducing cupric to cuprous chloride. These
are preferred but not limiting process limitations.
45 Sulfate ion is removed from the electrolyte after electrolysis
by precipitation with harium or calcium in the
purification step. The elemental sulfur formed in leach
1 is separated with the solids and is eventually removed
in the tails from which it is recovered hy a conventional
50 procedure.
As will he seen from the flow diagram, the chalcopyrite
residue from leach 1 is subjceted to two leaching
steps, that is, leach 2 and leach 3, This is done to insure
that suhstantially all of the copper is removed from the
55 chalcopyrite concentrate. Solution from leach 2 containing
some copper is continuously recirculated to
leach I. Leach 3 is performed with ferric chloride resulting
from oxidation of ferrous chloride in the spent
00 electrolyte. The spent ferric chloride leach solution
from leach 3 is not recirculated to leach 1 hut is passed
through the anode compartment of the cell for conversion
of the ferrous chloride therein to ferric chloride.
This solution entering the anode compartment is suh-
6." stantial1y depleted of ferric chloride which will have
heen cOllverted to ferrous chloride in the oxidation of
the chalcopyrite residue from leach 2, The CUprOUl;
copper presellt is oxidized to cupric chloride hefore the
BRIEF SUMMARY OF THE INVENTION
BRIEF DESCRIPTION OF THE DRAWING
The single drawing is a flow diugram of the process
of the invention.
In accordance with the invention. finely ground chalcopyrite
ore concentrate is treated with cupric chloride
in a first leaching step followed hy separation of the solution
and chalcopyrite residue. The copper in the solution
is further reduced with metallic copper or other
reducing agent to provide an electrolyte in which tl)e
copper is essentially all in the cuprous form. The electrolyte
is suhjected to electrolysis in an electrolytic cell
in which the anode and cathode compartments arc separated
hy a separator which prevents passage of ions of
iron and copper from the cathode to anode. The spent
electrolyte goes to purification for recovery of the metals
other than copper followed hy electrolytic recovery
of iron, with simultaneous regeneration of ferric chloride
at the anode. An alternative procedure at this
point is the removal of excess iron by hydrolysis with
oxidation of ferrous chloride to ferric chloride for recirculation.
The regenerated ferric chloride in hoth instances
is circulated to leaching and the spent ferric
chloride leach solution is circulated through the anode
of the cell as copper is heing plated at the cathode for
regeneration of ferric chloride for usc in further leaching.
The result is that all of the copper cun he recovered
from the electrolyte without the conversion of cuprous
to cupric ions with simultaneous use of the cathode for
plating copper and the anode to regenerate ferric chloride
for multiple leaehings with overall effective utilization
of electrical energy.
metallic copper in which essentially all of the copper is
reduced to cuprous chloride and the iron reduced to
ferrous chloride. The only regeneration of ferric chloride
is hy oxidation of the ferrous chloride in the spent
electrolyte. the resulting ferric chloride being used to 5
oxidize chalcopyrite residue from the initial cupric
chloride treatment of the chalcopyrite concentrate.
The patent teaches against the formation of ferric chloride
at the anode and to prevent this only a portion of
)0
copper is recovered from the cuprous chloride electrolyte
with enough heing It:ft in solution for the express
purpose of preventing the oxidation of ferrous to ferric
chloride at the anode. Electrolyte is circulated from
cathode to anode to prevent the cupric chloride heing I."
formed at the anode from contacting the cathode
where copper is being plated from cuprous chloride
electrolyte. The process does not provide for regeneration
of ferric chloride in the cell and is expressly directed
to the conversion of cuprous ions to cupric ions 20
during electrolysis.
Accordingly. the principal object of this invention is
to provide an improvement in the step for electrolytically
recovering copper from cuprous chloride electrolyte
produced hy treatment of chalcopyrite ores with 25
metal chlorides hy which efficient utilization of the cell
is ohtainedhy using the anode to regenerate ferric
chloride from spent ferric chloride leach solution while
copper is heing simultaneously plated at the cathode of 30
the cell cuprous chloride electrolyte without the conversion
of cuprous ions to cupric ions.
5
3,901,776
6
Partially reucted chalcopyrite resiuue from leach 2
45 gave the following analysis:
( 51
LEACH 3
Two hundred grams of the above residue entered
Leach 3 where the solution from the cathode operation
also entered after purification and regeneration. One
liter of this purified solution whkh contained mainly
ferric chloride in excess ( I I X.2 gil Fe'l+) encountered
the reactcu residue for a thorough leach. Thc lea<:hing
operation of Leach 3 was aimed at a complete depletion
of the coppcr in <:halcopyritc to produce tails
ready to be discarded. The leaching was performed at
IO('oC and at pH O.S.
It was found that the system allowed no possihility of
formation of cuprous ions, the solution leaving Leach
3 having the following analysis:
The ferric chloride formed is then circulated to leach
3.
Based on the chemical reactions of the process set
forth ahove and the use of the separator oetween anoIyte
and catholyte it is apparent that there is no possihility
for the conversion of cuprous to cupric ions in the
electrolytic cell. No cuprous ions from the <:atholyte
reach the anolyte to be converted to cupric ions as the
separator prevents the travel of cuprous ions from catholyte
to anolyte. In order to demonstrate that no cuprous
ions are introduced into the anolyte from lea<:h
3, and to demonstrate the efficient conversion of ferrous
ions from leach 3 to ferric ions with economical
use of electrical power during cell operation, the following
procedure was carried out using the flow sheet
of the invention with the results given below being 00tained.
All percentages are given as weight percentages.
pleted in copper is sent to the purification stage where
sulfate ion is removed as explained above.
In the purification stage, the last residue of copper
and undesired impurities such as zinc, lead, arsenic, an5
timony, bismuth, etc.. are removed from spent elcctroIyte
which then proceeds either to iron plating or hydrolysis
as shown in the flow diagram.
If the solution is sent to iron plating, iron is platcd at
the cathode for sale, The iron plating cells are equipped
10 with the same separators as the copper plating cells
thereby prevel1ting the mixing of catholyte and anolyte
and preventing migration of ferric ions from the anoIytc
to the catholyte. The depleted (anion) catholyte
goes to the anode of the iron cell where ferrous iron is
IS oxidized to ferric iron which is circulated to leach 3.
If the solution is sent to hydrolysis as an alternate
procedure, the purified ferrous solution is treated with
oxygen to regenerate ferric chloride and precipitate hy20
drated iron oxide in accordance with the following
equation:
:lFeCI" + 0.75 0" -. If.! Fe"O" + 2FeCI"
Element WL'ight (/;
SO Fe q.1
Cu 71
ZIl 002K
Ph (UIUK
So .'''.2
solution enters the anode. The chalcopyrite residue received
in leach 3 from leach 2 is heavily depleted in
copper. The process is operated so that lea<:h 3 will always
he <:onducted with a suhstantial excess of ferric
chloride so that all of the copper in the chalcopyrite
will he completely soluhilized and no copper will he
lost in the tails. The reaction is preferably conducted at
a temperature hetween 105°_110°C.
The leach solution entering lea<:h 3 from leach 2 with
residue will contain some cuprous ions in addition to
ferrous and cupric ions. However, as lea<:h 3 is done
with a suhstantial excess of ferric ion the following rea<:
tion occurs:
FeCl:. + CuCI -. FeCit + CuCI~
The result is that the solution le,lving leach 3 for the
anode contains suhstantially all of the iron as ferrous
iron with some little ferric iron, and all of the copper
as <:upric chloride with no cuprous chloride heing present.
This is essential for the economical conversion of
ferrous chloride to ferric <:hloride at the anode as the
oxidation of cuprous to cupric chloride takes precedence
over the oxidation of ferrous to ferric chloride
am] if any cuprous copper is present it will he oxidized 25
to cupric chloride hefore any ferrous chloride will he
oxidized to ferric chloride and this will suhstantially diminish
the efficiency of the cell in converting ferrous
chloride to ferric chloride.
As a precautionary measurc, not more than about 311
1'S'), of thc ferrous chloridc is oxidized to ferric chloride
at the anode hecause it is advisahle to always maintain
some ferrous chloride in the solution so that if the
cell operation is upsd at any time there will always he
some krrous ion at the anode for conversion of ferric 35
ion to kecp the ccll from discharging oxygen or chlorine.
The solution leaving the anode for leach 2 preferahly
<:ontains not more than about 1'S'/t ferric chloride, 15'7rferrous
chloride and the remainder <:upric chloride. 411
This means that the solution is high in ferric chloride
for dTecti\'C leaching in lea<:h 2 of the chalcopyrite residuc
frnm the reduction step. Rcactions I and 2 ahove
occur in kach 2. The solution from lea<:h 2, which is
recirculated to leach I, contains ferrous chloride plus
some cupric and cuprous ions.
In leach I the solution containing ferrous. cuprous
and some cupric ions is contacted with fresh feed so
that reaction 2 ahove occurs. Thus most of the <:upric
ions arc reduced to cuprous ions. However, chakopyrite
is insufficiently a<:tive to reduce all of the cupri<:
ion present to cuprous ion so that the solution overflowing
the first stage thickener contains ferrous plus
cuprous ions plus some cupric ions. Since it is required
that the cupric ions in the solution from leach I he at 55
a minimum during c1edrolysis. the solution is contacted
with recycled copper powder to reduce the remaining
<:upric ions to cuprous ions in accordance with
eq uation :I ahove. The result is that the solution which (,0
oecomes the electrolyte contains iron anu copper almost
exclusively as ferrous and cuprous ions.
At the c'lthode. copper powder is plated in three
stages. The copper from st;lge I is product coppcr ,II1U
may be sold as such or further refincd for sale. Copper 65
further depicted from the electrolyte in electrolytic
stages 2 anu J may be recycled to the reductinn stage
for the reduction of cupric ion. Thc electrolyte ue7
3,901,776
8
LEACH 1
Fc:\~
42.5 gJ I
F,-'~~
Ill).~ gil
Cu'
()
Cu' .
1.'.7 gil
S
144 gil
The fresh feed of chalcopyrite with head assay of:
was contacted with leach liquor from Leach 2, through
thickener 2 which contained essentially ferrous. cuprous
and some cupric ions with the following analysis:
Clear solution from Leach 3 with the ahove composi- 5
tion was fed to the cell anode during cell operation for
anodic oxidation whereby the ferrous ions were converted
to additional ferric ions at the anode.
The tails from Leach 3 ready for disposal were ana- 10
Iyzed to contain the following:
Zn
O.I'2t{'(
Ph
O.OIlY;'
Fe
7.IH';'
Cu
(1..'4';'
15
Fe .... ·•
II
Fe+ .
12() gil
Cu'
115 gil
Cu++
2H.2 gil
The overall recovery of copper after Leach 3 is
shown by the following metallurgical balance:
The leach liquor from Leach 2 was advanced to
Leach I as an overflow from thickener 2.
As stated previously, it is preferred not to oxidize all of
the ferrous ion to ferric ion in the cell operation.
Leach 2 received the anode processed solution having
the ahove composition from the cell anode. Partially
reacted chalcopyrite containing 26.4'k Fe; IH.Wk
eu and fl.HW,.j So from Leach I entered Leach 2. The
leaching operation was conducted at ROO-90°C anu at
pH 0.5. This leach consumed the available ferric ion in
the anode processed solution leaving a heavily copper
depleted chalcopyritc to be proceedcd to Leach 3 with
a composition as follows:
s~
o
"II- Copper
l.cm.:hing. Rcc(l\"cr~
'1<,1.54
Cu"
1".7 gil
Copper in
Tails
OAHg
LEACH 2
Cell Anode Conversion
Copper
S()luhiJi/cd
IOJ.52 g
Copper in
F~cd
104 g
The cell ano<Je received from the thickener overflow
of Leach 3 a clear solution with composition as indicated
ahove. The cell anode was operated at 120 amperes
per square foot of graphite anode area. At total
power input of 27 ampere-hours was used for the anodic
oxidation of ferrous ion to ferric ion at 75°C.
It was found that 54.9 grams of iron in ferric form
was produced through anodic oxidation of ferrous iron. 35
The rate of power consumption was 0.49 ampere-hours
per gram of Fe+++ processed. This FIGURE compared
with O.4H ampere-hours per gram Fe+++ (Fe++ to
Fe+++) theoretical. The current efficiency for the process
was 9R percent.
After completing the desired anodic reaction the solution
with the following composition was advanced to
leach 2:
The leach was conducted at HOOC and at ph 0.5. This
leach produced the partially reacted chalcopyrite
which entered Leach 2 with the composition indicated
------------------------ 20 earlier (see l.each 2 for the partially reacted chalcopyrite
analysis). As shown in the flow sheet. the leach liquor
was filtered and advanced to the cathode operation
wherehy the solution contacted recycled copper
powder from the cathode during the reduction process
25 to reduce cupric to cuprous copper. As a result the solution
entered the cathode as catholyte hearing mainly
ferrous and cuprous ions.
From the ahove data it is seen that the process of the
flow sheet operates with no cuprous ions heing con-
30 verted to cupric ions in the cell operation aIIII with the
use of the anode of the cell to convert ferrous chloride
in spent ferric chloride leach solution to ferric chloride.
with economical consumption of electrical power as
copper is heing plated at the cathode.
The process is not restricted to any particular numher
of electrolysis of leach stages, as more or less than
the three stages of each used for illustrating the invention
can he utilized. The spent ferric chloride from any
leaching stage can he sent to the anolyte for regenera-
40 tion so long as all of the copper in it is in the cuprous
stage. Each of the leaching stages may contain any
numher of leaching steps.
From the ahove description of the invention, it will
he noted that the advantage provided is that the cell
45 anode can he used for regeneration of ferric chloride
while copper is heing simultaneously plated at the cathode.
The advantage of this is that the ferric chloride regenerated
in the spent electrolyte can he used for a
numher of oxidation steps with regeneration to insure
50 complete removal of copper from the chalcopyrite concentrate,
the additional oxidation steps being possihle
hecause of regeneration of the ferric chloride between
steps in the anode of the cell. It is obvious that this is
much more economical than using oxygen in separate
55 oxidation steps for continued oxidation of the spent ferric
chloride leach solution from Leach 3 to rcgenerate
ferric chloride.
Although the invention has heen disclosed with the
/>0 usc of cupric chloride alone in l.eaeh I, it includes the
use of ferric chloride. Other reductants than metallic
copper can he useu to reduce the cupric chloride to cuprous
chloride in the reduction stage. Any excess sulfate
ions generated in the electrolysis process can he
(,5 rell\oved from the spent electrolyte by precipitation
with harium or calcium. The process can he conducted
with multiple stages of cells and may he conducted
hatch or continuous.
9
3,901,776
10
said second leach is returned to leach ( ) ).
3. The proccss of claim) performed as a continuous
process,
4. Thc process of claim) performed in multiple steps
5 and stagcs.
5. The process of claim I in which in step (b) the reduction
is performed with metallic copper.
6. The process of claim I in which the leaching materials
in step (a) include ferric chloride.
7. The process of claim I in which in step (0 up to
ahout X5lk of the ferrous chloride is oxidized to ferric
chloride.
8. In the process for recovering copper from copper
sulfide ores or their concentrates in which the ore or
15 concentrate is leached with cupric chloride and/or ferric
chloride, the resulting solution and residue separated,
substantially all of the copper chloride in the solution
reduced to cuprous chloride, the resulting cuprous
chloride solution electrolyzed to recover copper,
and the ferrous chloride in the spent electrolyte oxidized
to ferric chloride which is recycled for leaching
at least part of the chalcopyrite resiuue, the improvement
which comprises: conducting said electrolysis in
an electrolytic cell having an anode and a cathodt: divided
by a separator to keep ions of copper and iron
from travelling from the cathode to the <modt:, to recover
substantially all of the copper in solution at the
cathode without the formation of cupric copper in the
cell.
9. The improved process of claim 8 including soluhilizing
ut least a part of the copper in said residue with
said recycled ferric chloride to produce cupric chloride
and ferrous chloride in solution, introducing said latter
3S solution into the anode compartment of said electrolytic
cell to oxidize the ferrous chloride therein to ferric
chloride as metallic copper is being simultaneously recovered
at the cathode anu using the ferric chloride regenerateu
by the electrolytic oxidation of ferrous chloride
in the anode to leach additional chalcopyrite resiuue.
10. The improved process of claim 9 in which up to
about X5'H of the ferrous chloride in solution is convertcu
to ferric chloride in the anode compartment.
* * * * *
Whik the invention has been illustrated b) its application
to chalcopyrite. a common coppcr sultide mineraI.
it is equally applicable to other coppcr sullidc
minerals. such as. covellite and chalcm:itc.
What is claimed is:
I. A process for the recover) of clipper fnllll copper
sulfide orcs and their concentrates comprising:
a. leaching the ore or concentrate feed with a material
comprising cupric chloride ir a tirst leaching
stage with separation of thc solids from the result- I()
ing solution and sending the solids to a second
leaching stage:
b. reducing substantially all of the copper t:hloride
content of the solution from said tirst leaching
stage to t:uprous t:hloride;
c. recovering copper from the solution of step (b) by
subjet:ting the solution to electrolysis in the cathode
compartment of an electrolytic cell having an
anode and a cathode and a separator therebetween
to keep ions of copper and iron from travelling 20
from the cathode to the anode, with the ferrous
chloride ions in the cathode unaffected by the electrolysis;
d. leaching the solids from said first leaching stage
with materials comprising ferric chloride and cu- 25
pric chloride with separation of the solids and spent
leach solution and sending the latter to said. first
leaching st<lge and the solids to a third leaching
st<lge;
e. oxidizing the ferrous chloride in the spent t:atho- 30
Iyte from said electrolysis to ferric chloride and
sending the ferric chloride to said third leaching
stage to leach the solius from said second leaching
stage followeu b) separation of the resulting solius
anu spent leach solution, and
f. introducing the spent leach solution of step (e)
containing ferrous. ferric and cupric chlorides into
the anoue compartment of saiu cell to oxidize saiu
ferrous chloriue to ferric chloride with the cupric
chloride being unaffected by the electrolysis, and ~o
transferring said electrolytically oxiuized solution
to said second kat:hing stage; wherehy the electrolytic
cell is operated without the t:onversion of any
cuprous ions to cuprk ions.
2. The process of claim 1 in which the solution from ~5
(,0