4,013,457 Process for the recovery of cuprous chloride in the presence of metal impurities

Patent Number/Link:

United States Patent

Goens et ale

[ 19] [ II ]

[45]

4,013,457

Mar. 22, 1977

[54] PROCESS FOR THE RECOVERY OF

CUPROUS CHLORIDE IN THE PRESENCE

OF METAL IMPURITIES

[75] Inventors: Duane N. Goens; Paul R. Kruesi,

both of Golden, Colo.

[73] Assignee: Cypnas MetaUurgical Processes

c:orporation, Los Angeles, Calif.

[22] Filed: Feb. 24, 1975

[21] Appl. No.: 552,694

[52] U.S. CI 75/104; 75/108;

75/117; 423/34; 423/493; 423/42; 423/658.5;

23/300

[51 ] Int. CI.¥ C22B 3/00; CO IG 3/04

[58] F"aeId of Search 23/300, 305; 75/104,

75/117, 108; 423/34, 23, 27, 32, 493, 42

[56] References Cited

UNITED STATES PATENTS

A process is disclosed for separating cuprous chloride

from a solution comprising cuprous chloride and one or

more of a number of metal impurities, the process

comprising crystallizing the cuprous chloride from the

solution in the presence of copper as cupric chloride in

a concentration of at least about 20 grams per liter. In

one embodiment, the process is employed for recovering

substantially pure copper from copper sulfide concentrates

containing one or more metal impurities, the

basic process comprising leaching the copper sulfide

concentrates with ferric chloride to. produce a leach

solution comprising cuprous chloride, cupric chloride,

ferrous chloride and the metal impurities, crystallizing

a substantial portion of the cuprous chloride from the

leach solution in the presence of cupric ion in a concentration

of at least about 20 grams per liter in order

to produce substantially pure cuprous chloride and a

mother liquor, separating the crystallized cuprous

chloride from the mother liquor, reducing the crystallized

cuprous chloride to substantially pure elemental

copper, treating a substantial portion of the mother

liquor with oxygen and hydrochloric acid to produce

iron oxide, cupric chloride and ferric chloride, and

treating the remainder of the mother liquor in order to

remove the impurities.

2.586.579

3.785.944

3.798.026

3.865,744

3,879.272

2/1952

1/1974

3/1974

2/1975

4/1975

Supiro 423/34

Atwood et al. 75/117 X

Milner et al. 75/104

Parker et al. 423/27 X

Atwood et al. 75/104 X

[57] ABSTRACT

PrilrUlry Examiner-James H. Tayman, Jr.

COPPER

SULFIDE

FEED

25 Claims, 1 Drawing Figure

FERRIC CuCI

CHLORIDE

CuCl CuCl. FeCI.

CRYSTAlLIZATION .--.. Cu REMOVAL Co

LEACH

IMPURITIES

[Cu+2]·> 2.09/1

TAL

SOLID

CuCl, euc.., FeCI.

LIQUID

IMPURITIES IMPURITIES

SEPARATION

IMPURITIES REMOVAL

culCI I

CRYStALS T~

CuCI IRON

REDUCTION ELECTROYLSIS Tr ~, J FeCI, I I Cuo

CUCI2 I HYDR:lLYSIS I

~ j'3 '.

F'P3

COPPER

SULFIDE

FEED

FERRIC CuCI

"CHLORIDE

CuCI. CuCI? FeCI?

CRYSTALLIZATION ,- Cu REMOVAL

Cuo

IMPURITIES

LEACH [Cu+2J > 2Og/1

TAILS

SOLID

LIQUID

CuCl, CuCI2 FeCI2 IMPURITIES IMPURITIES

IMPURITIES REMOVAL

SEPARATION

culc, I

CRYStALS Fet'2

CuCI IRON

REDUCTION ELECTROYLSIS

HCI ! r ~

FeCI7,

Cuo

HYDROLYSIS

Feo

CuCI2 ..

FeCI3

Fep3

c..en

(1) a

,.N.

-...J

'"o

I-ool

'"~

-.l

4,013,457

PROCESS FOR THE RECOVERY OF CUPROUS

CHLORIDE IN THE PRESENCE OF METAL

IMPURITIES .

BACKGROUND OF THE INVENTION

I. Field of the Invention

The process of this invention deals generally with

selective crystallization, as classified in Class 23, SubClass

296; and more particularly with the selective

crystallization of cuprous chloride from particular solutions

containing particular amounts of cupric chloride.

2. Prior Art

The separation of cuprous chloride from solutions

possessing one or more of a number of metal impurities

presents a problem, particularly in the rapidly developing

hydrometallurgical copper recovery processes. As

is well known, the main sources of copper today are

copper sulfide ores; primarily chalcopyrite. Conventional

pyrometallurgical techniqiJes for recovering copper

from its sulfide ores are objectionable due to the

production of sulfur dioxide, a major air pollutant.

Accordingly, hydrometallurgical developments are

now being considered in the copper industry to produce

pollution free processes for the recovery of copper

from its sulfide ores.

Many of these hydrometallurgical processes are concerned

with leaching the copper sulfide ore with ferric

chloride and/or cupric chloride to form elemental sulfur

prior to the recovery of the copper. The sulfur

dioxide pollution problem is eliminated in these processes

by converting of the sulfide sulfur directly to

elemental sulfur.

One of the principal difficulties in these processes is

the comple~econversion of the copper in the copper

sulfides to.cuprous chloride, the preferred intermediate

for the production of elemental copper. Generally the

leaching reactions produce a mixture of cuprous chloride,

cupric chloride and ferrous chloride. The prior art

then reduces the cupric chloride to cuprous chloride,

generally by means of elemental copper, in order to

produce ." a solution containing only cuprous chloride

and ferrous chloride, which may then be conventionally

treated for the production of copper. This 'is necessary

in that cupric chloride is not easily reduced to

elemental copper in the presence of the various impurities

which exist in the solutions, and also due to the fact

that substantially more energy is required in order to

perform this reduction. U.S. Pat. No. 3,798,026 to

Milner illustrates such a process. Milner leaches his

copper concentrate to produce a solution containing

cuprous, cupric and ferrous chlorides, reduces the cupric

chloride to cuprous chloride by means of cement

'copper, crystallizes a portion of the cuprous chloride

from the resulting leach solution and reduces this cuprous

chloride by means of hydrogen reduction to elec

mental copper, and treats the mother liquor from the

crystallization step in order to produce cement copper,

regenerate the leach reagents and remove the various

impurities.

Another similar process is described in. U.S. Pat. No.

3,785,944 to Atwood. This process discloses the recovery

of metallic copper from chalcopyrite by leaching

the chalcopyrite with ferric chloride to produce cupric

chloride, reducing a portion of the cupric chloride to

cuprous chloride by reacting it with fresh chalcopyrite

feed, reducing the remaining cupric chlorice with metallic

copper, reducing the cuprous chloride to metallic

copper by electrolysis and conventionally regenerating

the ferric chloride leach reagent and removing the

impurities.

These and other similar processes represent notable

5 advances in the art, but possess severalimportant drawbacks.

The electrolytic recovery of copper directly

from the reduced ,leach solution, as disclosed in Atwood,

produces a relatively impure grade of copper

due to the amount of impurities plated with the copper

10 during electrolysis. Also, in order to reduce the cupric

chloride to cuprous chloride it is necessary to utilize

elemental copper which has already been processed.

This elemental copper is oxidized to cuprous chloride

by the reaction ~ith cupric chloride. Hence, this COpe

15 per must remain in the process for a relatively lengthy

period of time and additional energy must be consumed

in order to again convert the cuprous chloride to elemental

copper.

The Milner process represents an advance in the

20 purity of the copper produced since in this process the

cuprous chloride is first crystallized. from the leach

splution prior to its" reduction to elemental copper.

However, since a substantial amount of process impurities

crystallize with the cupric chloride, Milner must

25 either remove these impurities prior to crystallization

or further treat the cuprous chloride crystals in order to

remove the impurities. Furthermore, Milner's method

of crystallization requires that all of the cupric chloride

be reduced by means of elemental copper to cuprous

30 chloride prior to the crystallization step, and as mentioned

earlier this requires a substantial energy expense

from the standpoint of oxidizing elemental copper

which had previously been reduced, and also requires a

substantially prolonged residence time before all of the

35 copper is ultimately produced.

The process of this invention overcomes these drawbacks

and presents several significant advantages. A

particularly important advantage which results from

the application of this process is that a substantially

40 increased amount of cuprous chloride may be maintained

in and therefore crystallized from the solution.

The addition of cupric chloride increases the capacity

of the solution for cuprous chloride while simultaneously

minimizing the amount of iron in solution. As

45 iron in solution presents a considerable problem during

the separation of the cuprous chloride crystals from

solution and the subsequent washing of the crystals,

minimizing the amount of iron is highly desirable.

Another particularly important advantage is realized

50 as a result of conducting the crystallization in the presence

of one or more metal impurities commonly encountered

in copper bearing ores. It has been surprisingly

discovered that when the cuprous chloride is

crystallized from a solution containing a substantial

55 amount of cupric chloride that the amounts of certain

impurities crystallized is vastly reduced. The cupric

chloride apparently inhibits the inclusion of these impurities

with the cuprous chloride crystals. The resulting

cuprous chloride crystals are observed to be so pure

60 in some instances that they may be directly reduced to

elemental copper without the necessity of any additional

purification processing. The crystallization step

of this process may therefore be carried out without the

necessity of first removing these impurities, as is re-

65 quired in the Milner process.

Furthermore, another primary advantage is recognized

from the standpoint of the' amount of energy

required to conduct the process. As earlier mentioned

4,013,457

when elemental copper is employed to reduce cupric

chloride to cuprous chloride prior to crystallization the

elemental copper is oxidized to cuprous chloride. The

initial energy required to produce this elemental copper

is wasted since additional energy must be consumed

to again reduce the cuprous chloride to elemental

copper. The process of the present invention obviates

the reduction of this cupric chloride, thereby saving

the considerable additional energy.

Utility

In its broadest aspects the process of the present

invention isolates cuprous chloride from a solution as

herein described. As is well known in the chemical

literature, cuprous chloride is useful in a number of

applications, including serving as an intermediate in

various chemical reactions. Its primary commercial

value is as an intermediate for the recovery of copper

from various copper bearing ores.

SUMMARY OF THE INVENTION

This invention deals with a process for crystallizing

cuprous chloride from a solution comprising cuprous

chloride and one or more metal impurities selected

from the group consisting of antimony, arsenic and

bismuth, the critical requirement being that the crystallization

take place in the presence of a cupric ion concentration

of at least about 20 grams per liter.

This crystallization process is of primary value in

processes for recovering copper from copper bearing

ores, particularly copper sulfide ores, generally comprising

concentrating the copper bearing ores, leaching

the concentrate with ferric chloride in order to produce

a solution comprising cuprous chloride, cupric chloride,

ferrous chloride and the various metal impurities

existing in· the concentrate; crystallizing a substantial

portion of the cuprous chloride from the leach solution

resulting in cuprous chloride crystals and a mother

liquor, which crystallization is performed in the presence

of a cupric ion concentration of at least about 20

grams per liter; separating the crystallized cuprous

chloride from the mother liquor; reducing the crystallized

cuprous chloride to elemental copper; treating a

substantial portion of the mother liquor with oxygen

and hydrochloric acid in order to produce iron oxide

and to regenerate cupric chloride and ferric chloride;

and treating the remainder of the mother liquor in

order to remove the various impurities.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE sets forth a process flow diagram incorporating

the process of the invention in a particular

process for recovering copper from chalcopyrite feed

materials.

DESCRIPTION OF THE PREFERRED

EMBODIMENTS

The invention primarily deals with an improved crystallization

process for removing cuprous chloride from

various solutions. Solutions suitable for the application

of this process are those which comprise cuprous chloride

and one or more metal impurities selected from the

group consisting of arsenic, antimony and bismuth. The

solution must also comprise at least one suitable cuprous

chloride solvent. A "suitable solvent" as the term

is used throughout the specification and claims includes

metal chlorides possessing sufficient solubility

for cuprous chloride, preferably within the temperature

range of about 40° C to about 100° C, including, for

example, hydrochloric acid, the alkali metal chlorides,

the alkaline earth metal chlorides, ferrous chloride and

cupric chloride. Similarly the term suitable solution is

5 intended to mean a solution possessing the above set

forth characteristics.

The physical separation process employed with the

process of the invention is crystallization. The term

crystallization as used herein is intended to mean the

10 physical process of cooling the solution in order to

decrease the solution's capacity for cuprous chloride,

thereby depositing the cuprous chloride as a solid. It is

observed that this is within the ordinary context of the

term when the term is employed in relation to solu-

15 tions.

The amount of cuprous chloride in solution is not

critical to the process, but when maximizing the yield

of cuprous chloride crystals is desired it is preferred to

operate the process with a solution at or near the satu-

20 ration of cuprous chloride. Similarly the upper temperature

limitation of the solution is not particularly important,

as long as the temperature is below the boiling

point of the solution. Of course generally speaking the

higher the temperature of the solution the greater ca-

25 pacity it will have for maintaining additional cuprous

chloride in solution. The solution is therefore preferably

maintained from about 80° to about 107° C prior

to the crystallization.

The solution may be cooled by most conventional

30 means known in the art, such as heat exchange with

other process streams, the use of cooling water, refrigeration,

and other well known techniques.

The solution should be cooled to preferably at least

about 30° C, more preferably at least about 20° C, and

35 most preferably at least about 10° C. The yield of cuprous

chloride crystals generally increases as the temperature

range which the solution is cooled increases.

Necessarily when cuprous chloride is crystallized

from a solution in the presence of one or more of the

40 enumerated impurities some of the impurities will be

separated from the solution with the cuprous chloride.

Further removal of these separated impurities is necessary

if relatively pure copper is to be recovered from

the crystallized cuprous chloride. This of course re-

45 quires additional processing, as is disclosed, for example,

in U.S. Pat. No. 3,798,026.

However, when cuprous chloride is crystallized from

a suitable solution in the presence of sufficient cupric

ions, the amounts of impurities concurrently separating

50 are substantially reduced. This facilitates any additional

purification processing, and in many cases actually

eliminates the necessity for additional purification.

The presence of cupric ion, preferably in the form of

cupric chloride, during the cuprous chloride crystalli-

55 zation is therefore critical to the process. The minimum

concentration of cupric ion necessary to achieve the

advantageous results of the process is at least about 20

grams per liter, more preferably at least about 50 grams

per liter and most preferably at least about 100 grams

60 per liter.

The suitable solution from which the cuprous chloride

is crystallized may result from a number of processes.

Essentially the only requirement of such a process

is the production of a suitable cuprous chloride

65 solution. ·Preferable processes include those which

comprise leaching copper sulfide ores to produce a

solution comprising cuprous chloride, cupric chloride

and a suitable metal chloride solvent.

4,013,457

(4)

(I)

(2)

(3)

3CuCI2+ CuFeS2 -> 4CuCi + FeCI2+ 2S

4FeCI,. + CuFeS2 -> FeCl2+CuCl2+ 2S

FeCI" + CuCI -> FeCI2+ CuCl2

Any remaining chalcopyrite will be removed and sent

to third stage. The second stage leach solution therefore

contains ferrous chloride, cupric chloride and

cuprous chloride. The ratio of cuprous to cupric chloride

depends upon the reaction conditions employed in

the second stage leach. .

The second stage leach solution, after having been

separated from the remaining chalcopyrite, is then

recirculated to the first stage wherein it is contacted

with the fresh chalcopyrite feed. If grinding is employed

a portion of this solution may be mixed with the

feed prior to the grinding. The leach solution containing

ferrous chloride, cuprous chloride, and cupric

chloride react with the fresh chalcopyrite feed according

to the following reaction. .

This reaction is preferably conducted such that essentially

all of the ferric chloride is converted to ferrous

chloride. The cupric chloride present in the system in

turn reacts with chalcopyrite in order to produce cuprous

chloride and ferrous chloride as follows:

The tails are then separated from the solution and

discarded. This third stage leach solution, containing

ferric chloride, ferrous chloride and cupric chloride is

then introduced into the second stage. .

The second stage receives partially depleted chalcopyrite

from the first stage and the third stage leach

solution. Additionally, regenerated ferric chloride and/

or cupric chloride may be added at this stage. Again

the primary reaction in this second stage is:

In order to insure the consummation of all of the

chalcopyrite a substantial excess of ferric chloride is

preferably employed at this stage. This excess ferric

chloride will react with any cuprous chloride present to

produce ferrous chloride and cupric chloride as follows:

The leach stage of the process is designed to dissolve

the feed material and convert the sulfide sulfur to elemental

sulfur while converting the copper sulfide copper

to cuprous and cupric chlorides. A number of such

5 processes are known in the art and would be suitable

for this process, including for example the processes

disclosed in U.S. Pat. No. 3,785,944, 3,789,026 and the

Minerals Science Engineering article, Vol. 6, No.2,

April 1974 by Dutrizac, et al. entitled Ferric Ion as a

10 Leaching Medium.

A preferable leaching technique, described herein

with respect to its applicability to chalcopyrite, involves

a three state countercurrent reaction utilizing

ferric chloride ;:md cupric chloride as the leaching

15 agents. This leach process is perhaps best understood

by first considering the third stage. This third stage

receives heavily depleted chalcopyrite from the second

stage and ferric chloride. The ferric chloride is obtained

by the regeneration of ferrous chloride in a later

20 stage of the process. The primary chemical reaction in

this third stage is:

The process flow diagram of the figure illustrates a

relatively general process for recovering copper utilizing

the particular crystallization process of this invention.

The copper sulfide feed material containing one

or more metal impurities selected from the group consisting

of arsenic, antimony and bismuth is introduced

into the leaching phase and reacted with ferric chloride

and cupric chloride to dissolve the copper and iron, if

present, and remove the sulfur. The remaining gangue

is removed as tailings and discarded. The resulting

leach solution primarily comprises cuprous chloride,

cupric chloride and ferrous chloride, along with various

metal impurities. The concentration of copper as cupric

chloride present is monitored to insure that it is at

least about 20 grams per liter. The leach reaction is

generally carried on within a temperature range of

about RO° to about 105° C.

Thi.s hot solution is then cooled to remove a substantial

portion of the cuprous chloride in crystal form. The

amount of cuprous chloride crystallized is dependent

upon the various factors affecting the solubility of this

compound, as earlier discussed. Depending on the

composition of the solution, this crystallized cuprous

chloride may be relatively free of impurities, and need

not undergo additional purification processing. How- 25

ever, if in particular cases addi~ional processing for

purification is desirable, means known in the art, as for

example set forth in U.S. Pat. No. 3,798,026, may be

employed. The cuprous chloride crystals may then be

reduced to produce substantially pure copper. This 30

copper may undergo melting and casting in order to

form pure ingots.

The mother liquor from the crystallization stage possesses

the same' composition as the .leach solution

which was introduced into the crystallization stage, 35

with of course the exception of a substantially reduced

cuprous chloride concentration. A substantial portion

of this mother liquor may be introduced into a regeneration

stage in order to recover a portion of the iron as

iron oxide, oxidize ferrous chloride to ferric chloride 40

and oxidize the remaining cuprous chloride to cupric

chloride. The iron oxide is removed from the process,

and the ferric and cupric chlorides are recirculated to

the leach stage in order to treat fresh feed material. The

remainder of the mother liquor is bled to the purifica- 45

tion stage of the process, wherein the cupric and cuprous

chlorides are reduced to elemental copper and

removed from the process and the remaining impurities

are conventionally recovered. The resulting iron solution

may be treated by iron electrolysis in order to 50

produce substantially pure iron at the cathode. The

anode reaction in the iron electrolysis oxidizes ferrous

chloride to ferric chloride, which is recirculated to the

leach stage in order to treat additional feed material.

The feed materials for which this process may be 55

employed include all copper bearing compounds which

are capable of being converted to cuprous chloride.

Suitable ores and concentrates include, for example,

chalcopyrite, bornite, chalcocite, digenite, covellite,

malachite, enargite, scrap copper and others. Chalco- tiO

pyrite is a particularly suitable ore for the process.

Due to the grade of ores now being mined, concentration

processes are commonplace. As a result of these

various concentration processes the feed material is

generally sufficiently fine in order to be directly intro- ti5

duced into the process. However, if necessary the feed

may be further subjected to grinding in order to enhance

the leach reactions.

(0)

(7)

EXAMPLE I

FcCI2+ HCI + 1/, O2 -> FeCI" + 112 H20

oFeCI2= 1.5 O2 -+ Fe20" + 4FeCI"

CuCI + HCI + '4 0, -> CuCI2+ V2 H20

employed the by-product hydrogen chloride formed

may be used in the regeneration stage.

The mother liquor from the crystallization stage comprises

ferrous chloride, cupric chloride and some cuprous

chloride, along with the various process impurities.

A substantial portion of this mother liquor stream

is sent to the regeneration stage. In this stage the ferrous

chloride is converted to ferric chloride and iron

oxide and the cuprous chloride is oxidized to cupric

chloride. The applicable reactions are as follows:

EXAMPLES

The following examples demonstrate the crystallization

of cuprous chloride from solutions comprising

cuprous chloride, the designated metal impurities, and

cupric chloride in various different concentrations.

Each solution was saturated with cuprous chloride at

80° C and then cooled to 15° C in order to crystallize

cuprous chloride. The amounts of each of the impurities

crystallized with the cuprous chloride were then

determined for each of the different cupric chloride

concentrations. The results of Examples 1-6 are set

forth in Table I, with the amounts of impurities 'which

were crystallized with the cuprous chloride being tabulated

for the various different concentration of copper

as cupric chlorides in solution.

The initial solution of about 175 ml. comprised 214

g./1. iron as ferrous chloride, no cupric chloride, 1.02

g./1. Sb and 0.20 g./1. As. The total equivalent chloride

The hydrogen chloride may be obtained from the

hydrogen reduction stage. The regenerated ferric

chloride and cupric chloride may be recirculated to the

leach stage in order to treat fresh feed material.

That portion of the mother liquor which is not processed

in the regeneration stage is treated in the purification

stage. Preferably, from about 3 to about 10

percent of the mother liquor is treated in the purification

stage, and this range may vary depending upon the

particular process employed and the impurity buildup

in the process. This portion of the moth/lr liquor is

initially treated for the removal of copper. This copper

removal may be accomplished, for example, by iron

cementation or electrolysis. A preferable electrolytic

process is that described by Hazen in U.S. Pat. No.

3,767,543. When electrolysis is employed a portion of

the ferrous chloride from the leach stage may be circulated

through the anode in order to oxidize this ferrous

chloride to ferric chloride. The ferric chloride may

then be reintroduced into the leach stage.

The solution from the copper removal stage is then

further purified, removing any copper residue and

40 other impurities such as zinc, lead, arsenic, antimony,

bismuth, etc. The remaining ferrous chloride solution is

then sent to iron electrolysis wherein iron and ferric

chloride are produced. Alternatively all or aportion is

sent to hydrolysis wherein ferric chloride and iron

oxide are produced, as was mentioned earlier. In either

case the ferric chloride produced may be utilized in the

leach reaction.

(5)

4,013,457

3CuCl, + CuFcS, -> 4CuCI + FeCI, + 2S

All of the cupric chloride is not converted to cuprous

chloride, as chalcopyrite is not a sufficiently active

reducing agent. Hence, the resulting leach solution 5

from the first stage contains cuprous chloride, ferrous

chloride, and cupric chloride. This solution is separated

from the remaining chalcopyrite, and the chalcopyrite

is sent to the second stage. The first stage leach solution

is monitored to insure that cupric ion is present in 10

sufficient concentration, as hereinabove discussed.

This solution is then sent to the crystallization stage. No

reduction of cupric chloride is necessary, nor in most

instances is it desirable.

Generally the process is conducted such that at least 15

a substantial amount of cuprous chloride is crystallized

from solution, and \Inder most circumstances it is preferable

to crystalize as much cuprous chloride as practical.

Preferably at least 25 percent of the cuprous chloride

is removed in the crystallization step, more prefer- 20

ably at least about 35 percent, and most preferably at

least about 50 percent is removed at this stage.

Impurities other than arsenic, antimony and bismuth

may also be present in the solution from which cuprous

chloride is crystallized. Many of these impurities, such 25

as lead and zinc, have essentially no tendency to separate

with the cuprous chloride and therefore do not

present a problem. Other impurities which may tend to

partially separate with the cuprous chloride may possibly

be beneficially inhibited by the process of the in- 30

ventor. One impurity, silver, if initially present is preferably

removed from the solution prior to the crystallization,

as a substantial amoun~ of silver crystallizes with

cuprous chloride. This silver removal may be accomplished

by means known in the art. If, however, some 35

impurities are crystallized with the cuprous chloride

they may be removed by additional purification techniques,

such as leaching or recrystallization, prior. to

the production of copper.

The cuprous chloride crystals are then separated

from the mother liquor. Conventional solid-liquid separation

techniques may be employed, including for example

centrifuging. These crystals may then be washed

as necessary prior to the reduction to elemental copper.

This washing is preferably conducted with dilute 45

hydrochloric acid. Under certain conditions, such as

when the suitable solvent consists of a relatively high

concentration of cupric chloride and a relatively low

concentration of ferrous chloride, the washing step is

facilitated since it is easier to remove iron from the 50

cuprous chloride crystals.

Once the crystallized cuprous chloride has been isolated

from the mother liquor, a numbr of techniques

may be employed in order to reduce the cuprous chloride

to elemental copper. The cuprous chloride may be 55

dissolved and the copper cemented from the solution.

Alternatively, it may be dissolved and recovered electrolytically

by means known in the art. A preferable

technique to be used in conjunction with this process is

to reduce the cuprous chloride by means of hydrogen 60

reduction. The hydrogen reduction process may be

carried out by various means known in the art, as for

example, those set forth in U.S. Pat. Nos. 1,671,003,

3,552,498; 2,538,20 I; 3,321,303 and others.

Upon completion of the reduction of the cuprous 65

chloride to elemental copper the elemental copper may

be further treated by melting and casting in order to

facilitate further handling. When hydrogen reduction is

4,013,457

EXAMPLE 10

The solution of Example 7 was once again duplicated,

except no ferrous chloride was provided and I 17

5 g./l. copper as cupric chloride was present, representing

a total equivalent chloride ion concentration of

about.i31.g./1.

The following table presents for examples 7-10 the

amounts of iron and bismuth crystallized from the solulOtions

with the cuprous chloride, along with the concentration

of copper in solution as cupric chloride, as a

resultlof cooling the solutions to 150 C.

15 TABLE II

Example No. Cu as Cue!, (g./I.) Fe (ppm) Bi (ppm)

7 0 270 14

8 20 180 13

20 9 170 20 11

10 117 0 9

TABLE I

EXAMPLE 6

EXAMPLE 5

Example No. Cu as CuCI, (g./I.) Sb (ppm) Fe (ppm) As (ppm.)

! 0 954 270 29

2 20.5 185 180 9

3 53.9 49 84 I

4 112 23 60 2

5 170 14 20 I

6 117 21 0 2

The solution c9mprised no ferrous chloride and I 17

g./1. copper as cupric chloride, with the rest of the

components equivalent to the solution of Example 2, 35

providing a total equivalent chloride concentration of

131 g./1.

The solution of Example 2 was again repeated except

present were 93 g./1. iron as ferrous chloride and 170

g'/1. copper as cupric chloride. The total equivalent

chloride ion concentration was about 260 g./1. 30

EXAMPLE 4

Again the solution of Example 2 was duplicated except

the initial solution contained 105 g./1. iron as ferrous

chloride and 112 g./1. copper as cupric chloride.

The total equivalent chloride concentration was about

264 g./1.

EXAMPLE 7

The initial solution of this example comprised 214

g./1. iron as ferrous chloride, no cupric chloride and

0.52 g./1. Bi. The total volume of the solution was 175

ml. and the solution was saturated with cuprous chloride

at 800C. The total equivalent chloride ion concentration

was 271 g./1.

What is claimed is:

1. A process for improving the separation of cuprous

25 chloride from at least one impurity selected from the

group consisting of antimony, bismuth and arsenic

wherein the cuprous chloride and impurities are in

solution comprising:

a. crystallizing the cuprous chloride from solution in

the presence of cupric ion, the cupric ion concentration

being maintained at at least about 20 grams

per liter during the crystallization; and

b. recovering the cuprous chloride crystals from the

solution.

2. The process of claim I wherein the solution solvent

is ferrous chloride. .

3. The process of claim 1 wherein the solution solvent

is sodium chloride.

40 4. The process of claim 1 wherein the concentration

of copper as cupric chloride is at least about 50 grams

per liter.

5. The process of claim 1 wherein the cuprous chloride

solution being crystallized is reduced to a tempera45

ture of at least about 300 C.

--------------------- 6. The process of claim 1 wherein the crystallized

cuprous chloride is separated from the remaining solution

and reduced to elemental copper.

7. The process of claim 1 wherein the metal impurity

50 in solution is antimony.

8. The process of claim I wherein the metal impurity

in solution is bismuth.

9. The process of claim 1 wherein the metal impurity

in solution is arsenic.

10. In a process for recovering copper from copper

sulfide ores and concentrates containing at least one

metal impurity selected from the group consisting of

antimony, bismuth, and arsenic comprising leaching

the copper sulfides to produce a leach solution compris-

60 ing cuprous chloride, cupric chloride, ferrous chloride

and the metal impurities; separating at least a portion

of the cuprous chloride from the metal impurities and

leach solution resulting in cuprous chloride crystals and

a mother liquor; separating the cuprous chloride crys-

65 tals from the mother liquor; reducing the crystallized

cuprous chloride to elemental copper; treating a portion

of the mother liquor with oxyg'en in order to produce

iron oxide, cupric chloride and, ferric chloride,

EXAMPLE 8

The solution of Example 7 was duplicated except 192

g./1. iron as ferrous chloride and 20 g./l. copper as

cupric chloride were provided. The total equivalent

chloride ion concentration was 267 g'/1.

EXAMPLE 9

The solution of Example 7 was again duplicated with

the exception of providing 93 g./1. iron as ferrous chloride

and I70 g'/1. copper as cupric chloride. The total

cquivalent chloride ion concentration was 260 grams

per liter.

concentration was about 271 g./l. and the solution was

saturated with cuprous chloride at 800 C.

EXAMPLE 2

The initial solution for this example having a volume

of about 175 ml. contained 192 g./l. iron as ferrous

chloride. 20.5 g./1. copper as cupric chloride, 0.72 g./1.

Sb and 0.20 g'/l. As. The total equivalent chloride concentration

was about 267 g./1. and the solution was

saturated with cuprous chloride.

EXAMPLE 3

The solution of Example 2 was duplicated with the

exception of providing initially 159 g./1. iron as ferrous

chloride and about 54 g./1. copper as cupric chloride.

The total equivalent chloride concentration was about

265 g./1.

4,013,457

and treating the remainder of the mother liquor in

order to remove the impurities; the improvement comprising

performing the cuprous chloride separation by

crystallization in the presence of eupric ion being maintained

in a concentration of at least about 20 grams per 5

liter.

11. The process of claim 10 wherein the crystallized

cuprous chloride is reduced by means of hydrogen

reduction.

12. The process of claim 10 wherein the regenerated 10

cupric chloride and ferric chloride arc. recycled to the

leach phase of the process.

13. In a process for improving the separation of cuprous

chloride from at least one impurity selected from

the group consisting of antimony; bismuth and arsenic, 15

wherein the cuprous chloride and impurities are in

solution with at least one cuprous chloride solvent

selected from the group consisting of the alkali metal

chlorides, the alkaline earth metal chlorides, hydrochloric

acid and ferrous chloride wherein the separa- 20

tion is performed by crystallizing a substantial portion

of the cuprous chloride from the solution, the improvement

comprising performing the separation in the presence

of cupric ion being maintained at a concentration

of at least about 20 grams per liter. 25

14. The process of claim 13 wherein the solution

solvent is ferrous chloride.

1"5. The process of claim 13 wherein the solution

solvent is sodium chloride.

16. The process of claim 13 wherein the concentration

of copper as cupric chloride is at least about 50

grams per liter.

17. The process of claim 13 wherein the solution

being crystallized is reduced to a temperature of at

least about 30° C.

18. The process of claim 13 wherein the crystallized

cuprous chloride is separated from the remaining solution

and reduced to elemental copper.

19. The process of claim 13 wherein the metal impurity

in solution is antimony.

20. The process of claim 13 wherein the metal impurity

in solution is bismuth.

21. The process of claim 13 wherein the metal impurity

in solution is arsenic.

22. The process of claim 13 wherein at least about 20

percent of the cuprous chloride is crystallized from the

solution.

23. The process of claim 1 wherein the cupric ion is

in the form of cupric chloride.

24. The process of claim 10 wherein the cupric ion is

in the form of cupric chloride.

25. The process of claim 13 wherein the cupric ion is

in the form of cupric chloride.

* * * * *

l��:T0�(D�Roman","serif";mso-fareast-font-family: HiddenHorzOCR'>of chloride from the system. The invention includes the

combination with the chlorination step of the recovery

of all chlorine as a gas so that the recovered gas can be

reused in the chlorination step. The process has the

overall advantage that it is pollution-free with no chlorine

gas escaping from the system and no lead or sulfur

compounds or vapors being released to the atmosphere.

What is claimed is:

1. A process for recovering metals from a sulfide ore

concentrate containing lead, silver and zinc sulfides

comprising the steps of:

a. chlorinating the concentrate to convert the metal 25

sulfides to metal chlorides and convert the sulfide

sulfur in the ore to elemental sulfur;

b. leaching the residue of step (a) with aqueous sodium

chloride to dissolve lead and silver chlorides

and remove these chlorides from the remaining 30

solids;

c. cooling the sodium chloride leach solution to precipitate

substantially all of the lead chloride followed

by separating it from the leach solution;

d. recovering the silver from the lead chloride de- 35

pleted leach solution remaining from step (c);

e. removing a bleed stream from the solution remaining

from step (d) and recycling the remainder of

the solution to the leach solution of step (b);

f. removing substantially all of the zinc and other

impurities from the bleed stream;

g. subjecting the bleed stream to electrolysis to produce

chlorine gas;

h. recycling the purified bleed stream to leaching step

(b); and

i. recycling the chlorine gas to the chlorination step

(a).

2. The process of claim 1 performed continuously.

3. The process of claim 1 in which any lead and silver

remaining in the bleed stream of step (e) is removed by 50

iron cementation before removal of zinc' in step (f).

4. The process of claim 1 in which zinc is removed

from the bleed stream of step(f) by neutralizing the

bleed stream with sodium carbonate to form sodium

chloride and zinc carbonate.

5. The process of claim 4 in which sodium hydroxide

formed in the electrolysis ofsodium chloride in step (g)

is carbonated to form sodium carbonate which is recycled

to the neutralization step.

6. The process of claim J in which the bleed stream

of step (h) is concentrated before recycling to leaching

step (b).

7. The process of claim 1 in which the concentrate is

chlorinated in step (a) by dry chlorination with dry

chlorine gas.

8. The process of claim 7 in which the dry chlorination

is carried out at a temperature below the melting

point of elemental sulfur.

* * * * *

ture between about 500 C and the melting point of

sulfur to convert substantially all of the sulfide

sulfur to elemental sulfur in solid form and to effect

conversion of the metal compounds to metal chlorides,

and recovering metal from the chlorides.

22. The process of claim 21 in which chlorination is

performed at a temperature between about 800 C and

the melting point of sulfur.

23. The process of claim 2] in which the minerals

10 contain silver.

24. The process of claim 23 in which the silver containing

mineral is tetrahedrite.

25. The process of claim 21 in which sulfur chlorides

formed during dry chlorination are reacted with the

15 metal sulfides to form metal chlorides and elemental

sulfur.

26. The process of claim 25 in which the process is

performed by introducing the metal sulfides and dry

chlorine gas countercurrently into the reaction zone

20 and an inert sweep gas is introduced into the reaction

zone to bring sulfur chlorides formed during the dry

chlorination into contact with metal sulfides entering

the reaction zone.

4,011,146

lead, silver recovered from the leach solution by cementation,

the leach solution after removal of lead and

silver therefrom recycled to the sodium chloride leaching

step, the improvement comprising preventing the

build-up of zinc in the leach solution in the leaching 5

step by removing a bleed stream from the lead and

silver depleted leach solution, removing zinc from the

bleed stream and recycling the bleed stream to the

leaching solution in the leaching step.

19. The process of claim 18 including subjecting the

bleed stream to electrolysis after removal of zinc therefrom

to produce chlorine gas and recycling the chlorine

gas to the dry chlorination step.

20. The process of claim 19 in which the zinc is removed

by precipitating it as zinc carbonate by the addition

of sodium carbonate, the sodium hydroxide produced

in the electrolyis is carbonated to sodium carbonate

and the sodium carbonate recycled to the zinc

precipitation step.

21. The process of recovering metal values from

minerals of the polymorphic series of complex metal

sulfides tetrahedrite-tennantite comprising:

a. subjecting the minerals to dry chlorination with

chlorine gas in the absence of oxygen at a tempera-