3,901,776 Process for the recovery of copper from its sulfide ores

Patent Number/Link:

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

~HYDRO;LYSIS I

IFe203

I FeCI3

FeCI

PROOUCT

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

IALTERNATE ~--- PURIFICATION

Fe II

02 iHYDROLYSIS I IFe CELL CATHODES

Fe203

I FeCI3 IFe CE LL ANODES III

Fe CI 3

3,90 1,776

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

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

3,40 1,776

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

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.

3,901,776

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

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

LEACH 1

Fc:\~

42.5 gJ I

F,-'~~

Ill).~ gil

Cu'

()

Cu' .

1.'.7 gil

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:

O.I'2t{'(

O.OIlY;'

7.IH';'

(1..'4';'

Fe .... ·•

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:

"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.

3,901,776

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