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
I
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
,.N.
~
\0
-...J
-...J
~
'"o
I-ool
W
'"~
Ul
-.l
4,013,457
1
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
2
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
3
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
4
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.
5
4,013,457
6
(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
8
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
7
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
9
4,013,457
10
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.
55
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.
11
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12
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.
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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.
* * * * *
14
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
13
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-
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