3,972,711 Cuprous chloride recovery process

Patent Number/Link:

United States Patent [19]

Goens et at.

[11 ]

[45]

3,972,711

Aug. 3, 1976

Primary Examiner-G. Ozaki

Attorney, Agent, or Firm-Sheridan, Ross & Fields

[52] U.S. CI. 75/117; 75/104;

75/1 08; 423/42; 423/46; 423/38; 423/39;

423/493; 23/296; 23/305 R

[51] Int. CI.2 C22B 15/12

[58] Field of Search 423/42, 38,46, 39,

423/493; 75/1 17, 108, 104; 23/296, 305

[54] CUPROUS CHLORIDE RECOVERY

PROCESS

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

both of Golden, Colo.

[73] Assignee: Cyprus Metallurgical Processes

Corporation, Los Angeles, Calif.

[22] Filed: Mar. 3, 1975

[21] Appl. No.: 554,685

[56]

3,785,944

3,798,026

References Cited

UNITED STATES PATENTS

1/1974 Atwood et al. 75/117 X

3/1974 Milner et al. 75/117 X

from a solution comprising cuprous chloride and at

least one metal chloride compatible with the solubility

of cuprous chloride, the process comprising crystallizing

the cuprous chloride from the solution in the presence

of cupric chloride in an amount such that the cupric

chloride to compatible metal chloride mole ratio

is at least about O. I. In one embodiment, the process

is employed fOr recovering substantially pure copper

from copper sulfide concentrates, generally 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 order to produce cuprous chloride crystals 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.

[57] ABSTRACT

A process is disclosed for separating cuprous chloride

12 Claims, 1 Drawing Figure

FERRIC

CHLORIDE

CuCl, CuCI2, FeCI~ CuCI CuO ,- Cu REMOVAL

LEACH CRYSTALLIZATION

TAL

SOLID

LIQUID

CuCl, CuCI~,FeClo IMPURITIES IMPURITIES

SEPARATION

REMOVAL

CJCI I

CRYyALS Fr

CuCI IRON

REDUCTION ELECTROLYSIS

HI' r c!o F!O

FeCI~ I HYDROLYSIS I

CuCI2 1 I

~3 FT3

COPPER

SULFIDE

FEED

COPPER

SULFIDE

FEED

FERRIC

-- CUCI, CUCI2' FeCI2 CHLORIDE

CuCI

LEACH

CRYSTALLIZATION

.--- Cu REMOVAL

Cuo ....

TAILS

SOLID

LIQUID

CuCI, CuCI?, FeCI? IMPURITIES IMPURITIES

SEPARATION

REMOVAL

....

I I CuCI

CRYS{ALS Fer2

CuCI IRON

REDUCTION

l Q2

ELECTROLYSIS

,J. l .. !.

_ 'F'eCI~

Cuo

HYDROLYSIS

~'; Feo

CUCI2

';" .

J FeCI!

Fe:P3

c..en

.....

..w.

-J

..N.

-J

too-a

CUPROUS CHLORIDE RECOVERY PROCESS

BACKGROUND OF THE INVENTION

3,972,711

conventionally regenerating the ferric chloride leach

reagent and removing the impurities.

These and other similar processes represent notable

advances in the art, but possess several importantdraw-

1. Field of the Invention 5 backs. The electrolytic recovery of copper directly

The process of this invention deals generally with from the reduced leach solution, as disclosed in Atselective

crystallization, and more particularly with the wood, produces a relatively impure grade of copper

selective crystallization of cuprous chloride from par- due to the amount of impurities plated with the copper

ticular solutions containing particular amounts of cu- during electrolysis. Also, in order to reduce the cupric

pric chloride. 10 chloride to cuprous chloride it is necessary to utilize

2. Prior Art elemental copper which has already been processed.

The separation of cuprous chloride from cupric This elemental copper is oxidized to cuprous chloride

chloride solutions possessing one or more of a number by the reaction with cupric chloride. Hence, this copof

metal impurities presents a problem, particularly in per must remain in the process lor a relatively lengthy

the rapidly developing hydrometallurgical copper re- 15 period of time and additional energy must be consumed

covery processes. As is well known, the main sources of in order to again convert the cuprous chloride to elecopper

today are copper sulfide ores, primarily chalco- rr:ental copper.

pyrite. Conventional pyrometallurgical techniques for The Milner process represents an advance in the

recovering copper from its sulfide ores are objection- 20 purity of the copper produced since in this process the

able due to the production of sulfur dioxide, a major air cuprous chloride is first crystallized from the leach

pollutant. Accordingly, hydrollletallurgical develop- solution prior to its reduction to elemental copper.

ments are now being considered in the copper industry However, since a substantial amount of process impurito

produce pollution free processes for the recovery of ties crystallize with the cupric chloride, Milner must

copper from its sulfide ores. 25 either remove these impurities prior to crystallization

Many of these hydrometallurgical processes are con- or further treat the cuprous chloride crystals in order to

cerned with leaching the copper sulfide ore with ferric remove the impurities. Furthermore, Milner's method

chloride and/or cupric chloride to form elemental sul- of crystallization requires that all of the cupric chloride

fur prior to the recovery of the copper. The sulfur be reduced by means of elemental copper to cuprous

dioxide pollution problem is eliminated in these pro- chloride prior to the crystallization step, and as men-

30 tioned earlier this requires asubstantial energy expense

cesses by converting of the sulfide sulfur directly to from the standpoint of oxidizing elemental copper

elemental sulfur. which had previously been reduced and also requires a

One of the principal difficulties in these processes is substantially prolonged residence time before all of the

the complete conversion of the copper in the copper copper is ultimately produced.

sulfides to cuprous chloride, the preferred intermediate 35 The process of this invention overcomes these drawfor

the production of elemental copper. Generally the backs and presents several significant advantages. A

~eaching ~eactio~s produce a mixture ?f cuprous .chlor- particularly important advantage which results from

Ide, cupnc chlonde an? ferro~s chlonde. The pnor. art the application of this process· is that a substantially

. then reduces the cupnc chlonde to cupro~s chlonde, increased amount of cuprous chloride may be maingenerally

by me.ans of el~~ental copper, In order. to 40 tained in and therefore crystallized from the solution.

produce a. solutl~n cont~InIng only cuprous chlo?de The addition of cupric chloride increases the capacity

and ferrous chlonde, whlc~.may then be c~:m~entlon- of the solution for cuprous chloride while simultaally

t~eated for th~ produc.tlon.of copper: This IS neces- neously minimizing the amount of irQn in solution. As

sary In that cup~c chlonde IS not· easIly .red~ced t? iron in solution presents a considerable problem during

~lemen.tal copp~r In the pr~sence of the vanous Impun- 45 the separation of the cuprous chloride crystals from

tIes which eXI.st In the solutions, ~nd als? du~ to the fact solution and the subsequent washing of the crystals,

that substa~tlally m~re energy IS reqUIred In order to minimizing the amount of iron is highly desirable.

pe.rform. thiS reduction. U.S. Pat. N,o. 3,798,026 t.o Another advantage results when this crystallization is

MIlner Illustrates such a process. MIln.er leache~ .hls carried out in the presence of one or more metal impucopper

concentrate to produce a solution contaInIng 50 rities commonly encountered in copper bearing ores. It

cuprous, cupric and ferrous chlorides, reduces the cu- has been discovered that when the cuprous chloride is

pric chloride to cuprous chloride by means of cement crystallized from a solution containing a substantial

copper, crystallizes a portion of the cuprous chloride amount· of cupric.chloride that the amounts of certain

from the resulting leach solution and reduces this cu- impurities crystallized is vastly reduced. The cupric

prous chloride by means of hydrogen re.duction to ele- 55 chloride apparently inhibits ,the inclusion of these immental

copper, and treats the mother lIquor from the purities with the cuprous chloride crystals. The resultcrystallization

step in order to produce cement copper, ing cuprous chloride crystals are observed to be so pure

regenerate the leach reagents and remove the various in some instances that they may be directly reduced to

impurities. . . elemental copper without the necessity of any. addi-

Another similar process is described in U.S. Pat. No. 60 tional purification processing. The crystallization step

3,785,944 to Atwood. This process discloses the recov- ofthis process may therefore be carried out without the

ery of metallic copper from chalcopyrite by leaching necessity of first removing these impurities, as is rethe

chalcopyrite with ferric chloride to produce cupric quired in the Milner process.

chloride, reducing a portion of the cupric chloride to Furthermore, another primary advantage is recogcuprous

chloride by reacting it with fresh chalcopyrite 65 nized from the standpoint of the amount of energy

feed, reducing the remaining cupric chloride to cu- required to conduct the process. As earlier mentioned

prous chloride with metallic copper, reducing the cu- when elemental copper is employed to reduce cupric

prous chloride to metallic copper by electrolysis and chloride to cuprous chloride prior to crystallization the

3,972,711

100°C is a suitable solvent. As used throughout the

specification and claims the term"compatible" is used

to describe. metal chlorides possessing this solubility

qualification. Examples of suitable metal chlorides

include ferrous chloride, sodium chloride, cupric chloride,

the remaining alkali metal chlorides and the alkaline

earth metal chlorides. Hydrochloric acid also possesses

this solubility qualification.

The solution may also possess one or more of a num-

10 ber of metal impurities which commonly exist with

copper bearing ores. Examples of such metal impurities

include antimony, lead, zinc, silver, bismuth and arsenic.

Anyone of these impurities may be present in

the solution, as well as any combination of more than

15 one of the impurities.

The physical separation process employed with the

process of the invention is crystallization. The term

crystallization as used herein is intended to mean the

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 solutions.

The amount of cuprous chloride in solution is not

critical to the process, but it is preferred to operate the

process with a solution at or near the saturation 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 capacity it will

have for maintaining additional cuprous chloride in

solution. The solution is therefore preferably maintained

from about 80° to about 107°C.

The amount of cupric chloride required in solution to

accomplish the improved cuprous chloride recovery is

essential to the process. A cupric chloride to compatible

metal chloride mole ratio of at least about 0.1

should be maintained. Preferably this mole ratio should

be .at least about 0.20 and more preferably at least

about 0.25.

The solution may be cooled by most conventional

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

most preferably at least about lO°e. The yield of cuprous

chloride crystals generally increases as the temperature

range which the solution is cooled increases.

Cuprous chloride may be crystallized from compatible

solutions in the absence of cupric chloride. How-

55 ever, the presence of cupric chloride in the one or more

compatible metal chloride solvents increases the solution's

capacity for cuprous chloride. Hence a greater

amount of cuprous chloride may be carried by and

therefore crystallized from the solution without in-

60 creasing the concentration of the compatible metal

chlorides. This is extremely advantageous in washing

and purifying the cuprous chloride following the crystallization

step as many of the potential compatible

metal chlorides, in particular ferrous chloride and so-

65 dium chloride, present difficult wash and purification

problems. By minimizing the amount of the compatible

metal chlorides present, these problems are significantly

facilitated.

elemental Gopperis 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.<r;he process of the present invention obvi- 5

ates the reduction of this cuprous 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, GUprous Ghloride is useful in a number of

applications, including serving as an intermediate in

various chemical reactions. Its primary commercial

value is a., an intermediate for the recovery of copper

from various copper bearing ores.

SlJt\1MARY OF THE INVENTION

This invention deals with a process for crystallizing 20

cuprous chloride from a solution comprising cuprous

chloride. and ,at least one additional metal chloride

compatible with the solubility of cuprous chloride, the

critical requirement being that the crystallization take

place in the, presence of cupric chloride in an amount 25

such that the cupric chloride to. compatible metal

chloride mole ratio is at least about 0.1. The process is

particularly adaptable to solutions possessing in addition

to the above set forth compounds one or more

metal impurities selected from the group consisting of 30

antimony, bismuth and arsenic.

; 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 35

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 40

resulting in cuprous chloride crystals and a mother

liquor, which crystallization is performed in the presenceof

a 'cupric chloride to ferrous chloride mole ratio

of at least about OJ; separating the crystallized cuprous

chloride from the mother liquor; reducing the 45

crystallized cuprous chloride to efemental 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 50

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 crystallizationprocess

for removing cuprous chloride from

various solutions. Solutions suitable for the application

of this process are those which comprise cuprous chloride

and at least one additional metal chloride within

which cuprous chloride is soluble. In other words any

metal chloride which will dissolve cuprous chloride in

the temperature range of approximately 40° to about

(I)

(2)

'The.tails. <j.r~ thensepaJ;atedJrow the. solution and

discarded, This!4irdstage leach solution, containing

In order' to insure theconsurnmation of all of the

chalcopyrite'asubstantial excess, of ferric chloride is

employedal this stage. This excess ferric chloride will

react with ailycuprouschloride present to produce

ferrous chlotide· and cupric chloride as follows:

3,972;7,11

5 6

The separation of cuprous chloride from a solu,ti911 cuprous.Fl1lorid<;: cqncentratiqn. A, substantial portion

possessing one. or ,more metal, impurities s~!ecteed frOITl of this mother licHIor may be introd!lced jnto,~regener~

the group consisting of antimollY' bisIJIllth ~nd arsenic, ation. ~tagejno~clerto recov<;:raportton of i~eiron a.s

is particularly ,effective. Nece~~rily. when, cuprol/S iron oxide, oxidize ferrous cp~orideto ferric. chlqride

chloride is crystallized from a solution in the presenc~ 5 anq.oxidize the remaining cuprouschlor~<ie to cupric

ofone or more ,of theseimpl\ri~ies some of the impuri- c410ride., The ironoxide:is, removed from the proc<;:ss,

ties will, be crystallized ,from thesoll\tion witn the cu- and the ferric and cupric chlorides are recirculated to

prous chloride. Further removal. of thl.<se crystallized the leach stage in order to treat fresh feed material. The

impurities is necessary if rela.tively pure copper istO,be remainder of the mother liquor' is bled to the purificarecovered

from the crystallized cuprous chloride., This 10 tion stage of the process, wherein the cupric and cuof

course requires additional processing, as is disclosed' prous chlorides, are reduced' to elemental copper and

in U.S. Pat. No. 3,798,026.' removed from the process and the remaining impurities

However, when cuprouschloride is crystallized from are conventionally recovered. The resulting iron solu~

a compatible solution in thee presence of sufficient cu- tionmay be treated in the iron electrolysis stage in

pric chloride. theamo!Jnts' of impurities concurrently 15 order to produce substantially pure iron atthe cathode.

crystallizing" are substantially reduced. This facilitates The anode reaction in the iron electrolysis oxidizes

any additional, purificati~m processing, ,and in many ferrous chloride to ferric chloride, which may be recircases

will actually eliminate the necessity for additional culated to the leach stage in order to treat additional

purification. Sufficient cupric chloride to accomplish

this impurities redu,ction improvement is generally 20 feed material.

within the preferred mole ratio limits set forth' above The feed materials for which this process may be

with respect to effecting improved cuprous chloride employed incluQe all copper bearing compounds which

recovery. . are capable of being converted to cuprous chloride'.

The solution from which the cuprous chloriQe is crys- Suitable ores and concentrates include, for example,

tallized may result from a number of processes. Essen- 25 chak;opyrite, bornite, chalcocite,digenite, covellite,

tially the ollly requirement of such a process is the malachite" enargite, scrap copper and others. Chalcoproduction

of a 'suitable cuprous chloride' solution. pyrite is a particularly suitable ore for the process.

Preferable processes include those which comprise Due to the grade of ores now being mined, concenleaching

copper sulfide ores to produce asqlutiori com- tration processes are commonplace. As a result ofthese

prising I!l.1prouschloride,cupricchloridea:nd compati- 30 various concentration ,proyesses the feed material is

ble metal chloride. generally sufficiently fine in order to bedirectlyintro-

The process flow diagram of the FlGURE illustrates duced into the process. Hqwl.<ver, if necessary the feed

a relatively general process for recovering copper uti- may be further subjected tq grinding in ()rderto enlizing

the particular crystallization process of this in- hance the leach reactions. '

vention. The copper sulfide feed material, primarily 35 The leach stage ofthe process is designed to dissolve

chalcopyrite,is introduced into the leaching phase and the feed material and convert the sulfide sulfur to elereacted

with ferric chloride and cupric chloride to mental sulfur while converting the copper to cuprous

dissolve the copper and iron and remove the sulfur. and cupric chlorides. A number of such processes are

The'remaining gangue is removed as tailings and dis- known in the art and would be suitable for this process,

carded. The resulting leach solution primarily com- 40 including for example the processes disclosed in U.S.

prises cuprous chloride, cupric chloride, and ferrous Pat. Nos, 3,785,944, 3,798,026 and the Minerals Scichloride,

along with various metal impurities as set ence Engineering article, Vol. 6, No.2, April 1974 by

forth above. The amount of cupric chloride present is Dutrizac, eta\. entitled Ferric Ion as a Leaching,Memonitored

to insure that the cupric chloride to ferrous dium.

chloride mole ratio is preferably at least about 0.1, 45 A preferable leaching technique, described herein

more preferably at least about 0.2, and most preferably with respect to its applicability of chalcopyrite, inat

least about 0.25. The leach reaction is generally volves a three stage countercurrent reaction utilizing

carried on within a temperature range of about 80°to ferric chloride and cupric chloride as the 'leaching

about 105°C. agents. This leach process is perhaps best understood

This hot solution is then cooled to remove a substan- 50 by first considering the third stage. This third stage

tial portion ofthe cuprous chloride in crystal form. The receives heavily depleted chalcopyrikftorn the second

amount of C?prouschloride c~ystallizedis .~epende~t stage arid ferric chloride. The ferric chloride is obupon

the vanous ~act~rs affect1l1g the s.olubdlty of thiS tained by the regeneration of ferrous chloride in alater

compoundas earlIer discussed. Depend1l1g on the com- stage ofthe process. The primary chemical reaction in

position ofthe solution, this crystallized cuprouschlor- 55 this third stage is: "

ide may be relatively free of impurities, and need not .

undergo additional purification processing. However, if 4FeCI3 + CuFes, --+. 5FeCI. + CuCi. + 2S '

in particular cases additional processing for purificationis

desirable, means known in the art, as for example

set forth in U.S. Pat. No. 3,798,026 may be ern- 60

played. The cuprous chloride crystals may then be

reduced to produce substantially pure copper..This

copper may undergo melting and casting in order to

form pure ingots, .

The mother liquor from the crystallization .stage pos- 65

sesses the same composition ,as the ,leach solution

which was introduced into the crystallization stage,

with of course the exceptionofa substantially reduced

3,972,711

(7)

(8)

(6)

FeCI, + Hel + '4 0, -+ FeCI3+ ~ H.O

6FeCI, + 1.5 0, -+ Fe,03 + 4FeCI"

CuCI + HCI + '4 0, -+ CuCl, + ~ H,O

(3)

3CuCI, +CuFeS, -+ 4CuCI + FeCI, + 2S (4)

3CuCI, + CuFeS, -+ 4CuCI + FeCI, + 2S

4FeCI" +CuFeS, -+ 5FeCI, + CuCl, + 2S

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:

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

impurities are crystallized with the cuprous chloride

they may be removed by additional purification techniques,

such as leaching or recrystallization, prior to

5 the production of copper.

The cuprous chloride crystals are then separated

from the mother liquor. Conventional solidcliquid separation

techniques may be employed, including for example

centrifuging. These crystals may then be washed

10 as necessary prior to the reduction to elemental copper.

This washing is preferably conducted with dilute

hydrochloric acid.

Once the crystallized cuprous chloride has been isolated

from the mother liquor, a number of techniques

15 may be employed in order to reduce the cuprous chloride

to elemental copper. The cuprous chloride may be

dissolved and the copper cemented from the solution.

Any remaining chalcopyrite will be removed and sent Alte~atively, it may be dissol~ed and recovered electo

the third stage. The second stage leach solution 20 trolytlcally by means known In the art. A preferable

therefore contains ferrou~ chloride, cuprous chloride technique to be used in conjunction with this process is

and cuprous chloride. The ratio of cuprous to cupric to reduce the cuprous chloride by means of hydrogen

chloride depends upon the reaction conditions em- reduction. The hydrogen reduction process may be

ployed in the second stage leach. carried out by various means known in the art, as for

The second stage leach solution, after having been 25 example, those set forth in U.S. Pat. Nos. 1,67 I,om,

separated from the remaining chalcopyrite, is then 3,552,498,2,538,201,3,321,303 and others.

recirculated to the first stage wherein it is contacted Upon completion of the reduction of the cuprous

with the fresh chalcopyrite feed. If grinding is em- chloride to elemental copper the elemental copper may

ployed a portion of this solution may be mixed with the be further treated by melting and casting in order to

feed prior to the grinding. The leach solution contain- 30 facilitate further handling. When hydrogen reduction is

ing ferrous chloride, cuprous chloride, and cupric employed the by-product hydrogen chloride formed

chloride reacts with the fresh chalcopyrite feed accord- may be used in the regeneration stage.

ing to the following reaction. The mother liquor from the crystallization stage comprises

ferrous chloride, cupric chloride and some cu-

(5) 35 prous 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

40 chloride. The applicable reactions are as follows:

ferric chloride, ferrous chloride and cupric chloride is

then introduced into the second stage. .

'Thesecond 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:

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 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 a

cupric chloride ratio within the limits hereinabove dis- 45

cussed. This solution is then sent to the crystallization

stage. No reduction of cupric chloride is necessary, nor The hydrogen chloride may be obtained from the

in most instances is it desirable. hydrogen reduction stage. The regenerated ferric

Generally the process is conducted such that at least chloride and cupric chloride may be recirculated to the

a substantial amount of cuprous chloride is crystallized 50 leach stage in order to treat fresh feed material.

from solution, and under most circumstances it is pref- That portion of the mother liquor which is not proerable

to crystallize as much cuprous chloride as practi- cessed in the regeneration stage is treated in the purifical.

Preferably at least about 25 percent of the cuprous cation stage. Preferably, from about 3 to 10 percent of

chloride is removed in the crystallization step, more the mother liquor is treated in the purification stage,

preferably at least about 35 percent, and most prefer- 55 and this range may vary depending upon the particular

ably at least about 50 percent is removed at this stage. process employed and the impurity buildup in the pro-

Impurities other than arsenic, antimony and bismuth cess. This portion of the mother liquor is initially

may also be present in the solution from which cuprous treated for the removal of copper. This copper removal

chloride is crystallized. Many of these impurities, such may be accomplished, for example, by iron cementaas

lead and zinc have essentially 1:\0 tendency to sepa- 60 tion or electrolysis. A preferable electrolytic process is

rate with the cuprous chloride and therefore do not that described by Hazen in U.S. Pat. No. 3,767,543.

present a problem. Other impurities which may tend to When electrolysis is employed a portion of the ferrous

partially separate with the cupro.us ;chloride may possi- chloride from the leach stage may be circulated

blybe beneficially inhibited by the process of the in- through the anode in order to oxidize this ferrous chlorventor.

One impurity, silver, if initially present ispref- 65 ide to ferric chloride. The ferric chloride may then be

erably removed from the solution prior to the crystalli- reintroduced into the leach stage.

zation, as a substantial amount ofsilver crystallizes with The solution from' the copper removal stage is then

cuprous chloride. This silver removal may be accom- further purified removing any last copper residue and

3,972;7'11

., TABLE IV

other impurities such as zinc, lead, arsenic, 'a:ntirhohy,

bismuth, etc. The remaining ferrous chloride solution is

then sent to iron electrolysis whereiniiron and ferric

chloride are produced. Alternatively all or a portion is

sent to hydrolysis wherein ferric .. chloride and iron 5

oxide are produced, as was mentionedeariier. In either

case the ferric chloride produced may be utilized in the

leach reaction. .

Example

No.

[FeCl.l

(g./I.)

445

391

331

109 o

[CuCI.)

.' (g./I.)

114

360

248

Fe in initial

solution

(g./I.)

214

192

159

Fe in CuCI

crystals

(ppm)

270

180

EXAMPLES 10

Example No.

4567

[FeCI.l

(g./I.)

350

[FeCI.)

(g./I.)

250

[CuCI.)

(g./I.)

100

150

[CuCI.)

(g./I.)

100

200

250

CuCI crystallized

(grams per initial

liter of solution)

109

124

130

CuCI crystallized

(grams per initial

liter of solution)

109

116

TABLE III

Example No.

[FeCI.!

(g./I.)

150

[CuCI.)

(g'/I.)

100

200

300

350

102

3,972,711

8. The process of claim 7 wherein the cuprous chloride

solution being crystallized is reduced to a temperature

at least about 30°C.

9.The process of claim 7 wherein the cupric chloride

to compatible metal chloride mole ratio is at least 5

about 0.2.

10. The process of claim 7 wherein at least about 25

percent of the cuprous chloride is crystallized from the

leach solution.

11. The process of claim 7 wherein the crystallized

cuprous chloride is reduced by means of hydrogen

reduction.

12. The process of claim 7 wherein the regenerated

cupric chloride and ferric chloride are recycled to the

leach phase of the process.

* * * * *