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
2
.
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 ....
1
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
~
~a
~
~
~
.....
~
0\
..w.
\0
-J
..N.
-J
too-a
too-a
1
CUPROUS CHLORIDE RECOVERY PROCESS
BACKGROUND OF THE INVENTION
3,972,711
2
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
4
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.
3
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:
8
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:
7
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
10
., TABLE IV
9
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.
13
14
15
16
17
[FeCl.l
(g./I.)
445
391
331
109 o
[CuCI.)
.' (g./I.)
o
44
114
360
248
Fe in initial
solution
(g./I.)
214
192
159
94
<I
Fe in CuCI
crystals
(ppm)
270
180
84
20
<I
EXAMPLES 10
Example No.
I2
3
Example No.
4567
[FeCI.l
(g./I.)
350
350
350
[FeCI.)
(g./I.)
250
250
250
250
[CuCI.)
(g./I.)
o
100
150
[CuCI.)
(g./I.)
o
100
200
250
CuCI crystallized
(grams per initial
liter of solution)
109
124
130
CuCI crystallized
(grams per initial
liter of solution)
81
96
109
116
TABLE III
Example No.
8
9
10
11
12
[FeCI.!
(g./I.)
150
150
150
150
150
[CuCI.)
(g'/I.)
o
100
200
300
350
53
68
81
95
102
3,972,711
11
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
10
15
20
25
30
35
40
45
50
55
60
65
12
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.
* * * * *