United States Patent [19]
Reynolds et all
[11]
[45]
4,276,084
Jun. 30, 1981
[54] HYDROMETALLURGICAL PROCESS FOR
THE RECOVERY OF LEAD
OTHER PUBLICAnONS
Mellor, "Comprehensive Treatise on Inorganic & Theoretical
Chemistry", vol. 7, 1927, Longmans, Green &
Co., N.Y., pp. 712 and 713.
Wong et al., World Mining and Metals Technology, Sep.
1976, pp. 603-622.
704,639
1,346,642
3,981,962
3,998,628
4,135,993
References Cited
U.S. PATENT DOCUMENTS
[57] ABSTRACT
Scheiner et al., 1978 Mining Yearbook, Colo., pp.
133-138.
Murphy et al., Bureau ofMines, RI (1976) 7913 pp. 1-8.
Haver, Bureau ofMines, RI 8105 (1976) pp. 1-17.
Muir et al., J. Australasian Inst. of Mining and Metallurgy,
No. 259 (Sep. 1976), pp. 23-35.
Bagdasarian, Trans. of Am. Electrochem. Soc., vol. 51,
1927, pp. 449-494.
Primary Examiner-G. Ozaki
Attorney, Agent, or Firm-Sheridan, Ross, Fields &
McIntosh
21 Claims, 1 Drawing Figure
A hydrometallurgical process is used to recover lead
from a lead-bearing ore concentrate. The lead-bearing
ore concentrate is leached with a solution of cupric
chloride in order to precipitate lead as lead chloride,
produce elemental sulfur and substantially leave the
balance of the ore concentrate sulfides in unreacted
form. The residue of the cupric chloride leach is
leached with a brine solution in order to solubilize the
lead chloride to the exclusion of the balance of the
residue. Thereafter, the lead chloride is crystallized
from the brine solution. Elemental lead may be obtained
by the reduction of the lead chloride crystals.
The present process avoids air pollution problems inherent
to smelting processes, allows for a high recOvery
of lead of 97% or greater and allows for the direct
production of a high purity lead.
Hoepfner 75/120 X
Elmore 423/94 X
Smyres et al. 423/94 X
Gandon et al. 423/98 X
Urn 423/98 X
7/1902
7/1920
9/1976
12/1976
1/1979
Inventors: James E. Reynolds, Golden; Alan R.
Williams, Denver, both of Colo.
Assignee: Hazen Research, Inc., Golden, Colo.
Appl. No.: 80,444
Filed: Oct. 1, 1979
Int. CI.3 ............................•................. C22B 13/04
U.S. CI 75/101 R; 75/114;
75/120; 423/94; 423/98; 423/494
Field of Search 75/101 R, 114, 120;
423/94, 98, 494
[75]
[73]
[21J
[22]
[51]
[52J
[58]
[56J
AIR1PbS ORE
IFe,CtZnlS
CuCI
Cu Clz !
LEACH IMPURITIES + Zn,Fe
LIQUID I SOLID REMOVAL
SEPARATION J.Cu VALUES
CuClz
S' HCI
PbClz
UNREACTED
STr
SULFIDE
GANGUE
BRINE PbClz1BRINE SOLUTION
PRESSURE PbClz PbClz
LEACH CRYSTALLIZATION CRYSTALS
+ +
LIQUID / SOLID SEPARATION
SEPARATION
AIR
1UNREACTED
Hi
CUPRIC
REGENERATION
HCI
Hz
PbClz
VAPOR
Hz
REDUCTION
S'
UNREACTED
SULFIDES
GANGUE
1Pb'
f----+s'
S'
RECOVERY
UNREACTED
f----+SULFIDES
'--__---' GANGUE
U.S. Patent
AIR
Jun. 30, 1981 4,276,084
AIR
PbS ORE
(Fe,Cu,ln)S ,.. i CuCI ,.
UNREACTED
1
SO
PbCll
UNREACTED
SULFIDE
GANGUE
Cu Cil
LEACH
+
lIQUlO / SOLID
SEPARATION
STEAM
,p •
BRINE
PRESSURE
LEACH
+
LIQUID / SOLID
SEPARATION
PbCll/BRINE
SOLUTION
IMPURITIES ......Zn, Fe
RENOVAL
!CU VALUES
CuClz
HCI
.. PbCll PbCll
CRYSTALLIZATION CRYSTALS ~
+
SEPARATION
CUPRIC
REGENERATION
HCI
H2
PbCI2
VAPOR
H2
J.
H2
REDUCTION
SO
UNREACTED
SULFIDES
GANGUE
r
Pbo
SO
RECOVERY
UNREACTED
I--~- SULFIDES
GANGUE
Fig_l
4,276,084
Disclosure of the Invention
Lead-bearing ore concentrates are leached with cupric
chloride under reaction conditions controlled in
such a manner so as to extract and precipitate lead as
lead chloride, produce sulfur ill elemental form, and
substantially leave the balance of the concentrate sulfides,
particularly zinc, iron and copper, in unreacted
form. Leach liquor is continuously sparged with air in
order to regenerate the cupric chloride leaching agent
in solution.
The residue from the cupric chloride leach is then
preferably leached with a brine solution in order to
solubilize the lead chloride to the exclusion of the balance
of the residue. This brine leach is preferably conducted
under pressure and at an elevated temperature in
order to enhance the dissolution of the lead chloride.
The lead chloride solution is then separated from the
residue, and the lead chloride is crystallized from the
solution. The crystallized lead chloride may then be
reduced to elemental lead, preferably by means of hydrogen
reduction.
The residue from the brine leach step can be further
treated in order to recover the elemental sulfur.
BRIEF DESCRIPTION OF THE DRAWINGS
The FIGURE represents a generalized flow diagram
showing one preferred lead recovery technique.
BEST MODE FOR CARRYING OUT THE
INVENTION
The process ofthe present invention is suitable for the
separation of lead values from metal sulfide ores. The
metal sulfides may be any of those commonly associated
with lead sulfide, and the process is particularly adaptable
to the separation of lead values from metal sulfides
selected from the group consisting of zinc, iron and
copper. The concentrations of the various sulfide starting
materials is not important to the proper conduct of
the process, and hence lead sulfide may exist in an
amount as low as deemed desirable for separation to an
upper limit of nearby pure lead sulfide. Hence lead may
be considered the primary product of the process, or
may be deemed as an impurity in conjunction with, for
example, a relatively high content zinc concentrate.
The optimization of process parameters will, of course,
vary depending upon the precise constituents of the
2
with hydrochloric acid, ferric chloride, cupric chloride,
oxygen, oxygen and chlorine, chlorine alone, and chlorine
with cupric chloride. The cupric chloride leach
reported was conducted at 95° C. under carbon dioxide
5 pressure with aIM hydrochloric acid concentration.
Zinc extraction was about 95% after 2 hours, and the
cupric leach was not recommended because of high
ferric and cupric concentrations along with the zinc
chloride in the leach solution. A further disclosure in
10 this article describes the use of cupric chloride as a
catalyst with a hydrochloric acid leach (1 to 5M HCI).
Oxygen pressure is used with this process.
A. B. Bagdasarian discloses "Reduction of Metallic
Chlorides by Hydrogen" in 51 Transactions ofthe American
Electrochemical Society, pp 449-494 (1927). The
basic reduction reaction is discussed as well as the theoretical
aspects of the process. The author discloses hydrogen
reduction of lead chloride in closed tubes, with
and without bubbling the hydrogen through the lead
chloride.
1
BACKGROUND ART
HYDROMETALLURGICAL PROCESS FOR THE
RECOVERY OF LEAD
DESCRIPTION
Technical Field
The process of the invention relates to the hydrometallurgical
recovery of lead from lead concentrates,
and is particularly applicable to separating lead from
zinc, iron and copper.
Prior Art Statement
A leach-electrolysis method for producing lead from 15
galena is disclosed by M. M. Wong and H. P. Haver of
the U.S. Bureau ofMines in Chapter 37 of World Mining
and Metals Technology: Proceedings of thf! Joint MMIPAIME
Meeting, Denver, Colo., USA, Sept. 1-3, 1976,
A. Weiss, Ed. (MMIJ-AIME, 1976). In this process, 20
high grade lead concentrates (about 68 weight percent
lead) are leached with ferric chloride and sodium chloride
for 15 minutes at 100° C. Lead chloride is crystallized
from solution at room temperature and the ferric
chloride leachant is regenerated with chlorine. The lead 25
chloride is then reduced by fused salt electrolysis to
elemental lead.
B. J. Scheiner and R. E. Lindstrom disclose a chlorine-
oxygen leaching technique in "Leaching Complex
Sulfide Concentrates Using Aqueous Chloride Oxida- 30
tion Systems" in the 1978 Mining Yearbook ofthe Colorado
Mining Association, pp 133-38. Lead concentrates
bearing about 50% lead are leached in a two-step procedure
carried out in a pressure reactor with continuous
addition of chlorine and oxygen. The ferric and cupric 35
chlorides extracted from the concentrate by the chlorine
and oxygen then react to extract lead and other
metals as their chlorides. Lead chloride is dissolved
from the leach residue by means of hot brine leach at
90' C., crystallized at room temperature, and the lead is 40
reduced by fused salt electrolysis.
A method for leaching galena with ferric chloride is
disclosed by J. E. Murphy, F. P. Haver and M. M.
Wong in "Recovery of Lead from Galena by a Leach
Electrolysis Procedure", Bureau of Mines Report of 45
Investigations No. RI 7913 (1974). This disclosure concerns
itself primarily with the electrolytic reduction of
lead from lead chloride, and discloses ferric chloride
leaching of the galena ore and dissolution of the formed
lead chloride in 25% brine solution at 100° C. Chlorine 50
is used to regenerate the leachant.
A further disclosure by F. P. Haver and M. M. Wong
entitled "Ferric Chloride-Brine Leaching of Galena
Concentrate" is published in Bureau ofMines Report of
Investigations No. RI 8105 (1976). Hot brine (100° C.) 55
and ferric chloride are used to leach the lead chloride
from the 68% lead-bearing ore, dissolving the lead chloride
as it is formed. Chlorine is used to regenerate the
leachant. This is an improvement over the process disclosed
in Bureau of Mines Report Number RI 7913, 60
described above, wherein the ferric and brine leaches
are not combined.
David M. Muir, Donald C. Gale, A. James Parker,
and Dion E. Giles, in "Leaching ofthe McArthur River
Zinc-Lead Sulphide Concentrate in Aqueous Chloride 65
and Chlorine Systems", J. Australasian Institute ofMining
and Metallurgy, No. 259 (September, 1976), disclose
a number of leaching techniques including leaching
4,276,084
3
starting material, consistent with the discussion of the
process conditions as hereinafter set forth.
The starting materials are generally concentrated by
techniques known to the art in order to separate the
metal sulfide values from a substantial portion of the 5
gangue material. The concentrated values are then preferably
crushed to a sufficiently small particle size in
order to facilitate the leach reaction: The preferred
concentrate particle size introduced to the leach step is
about -100 mesh, more preferably about -200 mesh, 10
and most preferably about - 325 mesh.
The ore concentrate is then leached with cupric chloride
under reaction conditions selected so as to extract
most of the lead values as lead chloride, while leaving a
substantial portion of the remaining metal sulfides, in- 15
cluding sulfides of zinc, iron and copper, in their unreacted
sulfide form. The lead chloride product is insoluble
in the solution, while the small portions of zinc,
copper and iron sulfides which are extracted as their
corresponding chlorides are dissolved in the solution. 20
The lead chloride product, along with the elemental
sulfur and unreacted residue, is separated following the
leach from the leach solution containing the relatively
small amounts of solubilized metal chlorides.
The required agent for the leach reaction is cupric 25
chloride, with the leach reaction generally being as
follows:
2CuC1Z+PbS---+2CuCI+PbClz+so
The total copper concentration during the leach reac- 30
tion is preferably maintained as low as possible in order
to enhance the selectivity of the separation. The cupric
chloride concentration is therefore selected for a given
feed concentrate and other leach variables so as to maximize
lead extraction from the sulfides, while minimizing 35
the amount of extraction of the remaining metal sulfides.
The cupric chloride concentration is primarily a
function of total copper in solution and solution emf,
and solution emf is primarily a function of the ratio of 40
cupric chloride to cuprous chloride. The total copper
concentration in solution is preferably maintained
within the range of from about 3 to about 100 grams per
liter, more preferably from about 5 to about 50 grams
per liter, and most preferably from about 8 to about 25 45
grams per liter.
As the leach reaction continuously reduces the cupric
chloride to cuprous chloride, a preferred technique for
regera.rating the cupric chloride leaching agent is to
continuously introduce oxygen and/or air into the leach 50
solution during the leach reaction, thereby oxidizing
cuprous chloride to cupric chloride. This oxidation
reaction occurs at the relatively low leach temperatures
preferred for this leach reaction.
The reduction of cupric chloride by means of the 55
primary leach reaction and the oxidation of cuprous ion
by means of the air sparging are preferably controlled
so as to maintain a cupric ion to cuprous ion ratio in
solution offrom about 1:20 to about 16:1, more preferably
from about 1:9 to about 4:1 and most preferably 60
from about 1:5 to about 3:1. Consistent with the preferred
cupric ion to cuprous ion ratio, the solution emf,
which is oxidizing, is preferably maintained during the
leach reaction from about 200 to about 500 millivolts,
. more preferably from about 250 to about 450 millivolts, 65
and most preferably from about 350 to about 400 millivolts,
as measured by saturated calomel/platinum electrodes.
A primary feature of the invention is the libera-
4
tion of the sulfide sulfur in elemental form. Solution
emf's below about 100 millivolts tend to produce hydrogen
sulfide .as opposed to solid elemental sulfur.
The total chloride ion concentration maintained during
the leach reaction is important for the proper conduct
of the reaction, and to solubilize those minor
amounts of metal sulfides which are extracted during
the leach. The chloride ion concentration is preferably
maintained at a level not substantially exceeding that
amount sufficient to keep the copper in solution. Chloride
ion in excess of this requirement detracts from the
selectivity of the process. The chloride ion concentration
is maintained primarily by the addition of sodium
chloride, although calcium chloride, lithium chloride
and potassium chloride may also be used as sources of
chloride ion. Preferably the leach· solution contains
from about 50 to about 300 grams of sodium chloride
per liter, and more preferably from about 100 to about
250 grams of sodium chloride per liter.
The acidity of the solution is significant from the
standpoint of selectively extracting the lead values to
the substantial exclusion of the other metal values. The
pH is preferably maintained from about 0.5 to about 4,
and more preferably from about 0.5 to about 2. The pH
is preferably maintained by the addition of hydrochloric
acid so as to result in a solution concentration of hydrochloric
acid up to about 20 grams per liter, more preferably
from about 1 to about 16 grams per liter, and most
preferably from about 3 to about 7 grams per liter. The
selectivity of the process is greatly diminished with
excessive hydrochloric acid concentrations, and it is
therefore preferable to use as small an amount as possible.
The temperature of the solution is preferably maintained
as low as possible, consistent with suitable lead
chloride extractions. The solution temperature may be
permitted to go as high as the boiling temperature under
atmospheric conditions by properly controlling the
other process variables, but generally speaking such
high temperatures result in greater extractions of other
metal sulfides in the concentrate. Hence the solution
temperature is preferably maintained at less than about
95° C., more preferably at less than about 75° C. and
most preferably at about 60° C. and less. The lower
limitation is primarily dependent upon suitable reaction
times, and at less than about 30° C. the extraction oflead
becomes too slow to be practical.
The reaction time is maintained so as to obtain sufficient
lead recovery while avoiding extraction of the
other metal sulfides. Hence the reaction time is preferably
kept to a minimum consistent with the desired lead
recoveries. Generally speaking, reaction times of from
about 10 minutes to about 4 hours are preferred, with
reaction times of from about 30 minutes to about 2 hours
being more preferred.
Following the leach reaction, the resulting solid
phase, containing unreacted sulfides, elemental sulfur
and lead chloride are separated from the leach solution.
The separated leach solution is then preferably treated
for additional regeneration of the cupric chloride leaching
agent, and a portion of the liquid phase is treated for
the remov!!l of impurities as necessary. The leach solution
regeneration is preferably conducted by air oxidation,
preferably within a temperature range of from
about 40° C. to about 60° C. Hydrochloric acid is preferably
added as the chloride ion source for the necessary
oxidation of cuprous chloride to cupric chloride.
PbC1z+Hz--+HCI+PbO
The furnace operates at between about 600· C. and
about 900· C., and it is generally preferred to employ
excess hydrogen in order to facilitate the reaction. The
lead chloride reduction with hydrogen produces hydrochloric
acid, which as discussed earlier, may be scrubbed
with spent leach liquor from the cupric chloride
leach stage in order to remove the hydrochloric acid
and any unreduced lead chloride from the gas and provide
a source of chloride ions for the oxidation of cuprous
chloride to cupric chloride.
EXAMPLES
Example 1
Concentrates of compositions as hereinafter presented
were leached with various agents as set forth in
Table 1. Various feed materials were used, designated
concentrates A, B and C. Concentrate A comprised 73.9
percent lead, 0.954 percent zinc, 0.559 percent copper,
and 3.14 percent iron. Concentrate B comprised 25.1
percent lead, 9.57 percent zinc, 0.36 percent copper,
16.3 percent iron. Concentrate C comprised 12.4 percent
lead, 7.53 percent zinc, 2.9 percent copper and 30.4
percent iron. In Test 1, Concentrate A was leached with
hydrochloric acid alone. In Test 2 Concentrate A was
subjected to a ferrous leach with hydrochloric acid,
with oxygen continuously sparged into the slurry to
oxidize the ferrous to ferric ions. Test 3 involved a
cuprous leach, with gradual addition of the feed and
continuous oxygen sparging to oxidize the cuprous to
cupric and prevent the slurry oxidizing emf from dropping
below about +100 millivolts. Test 4 involved the
direct addition of 20 percent excess cupric ion with
6
clones, which permit the pressure to be reduced to
atmospheric pressure while employing the pressure
drop and hydroclone mechanism to effect the liquidsolid
separation. Hydroclone techniques such as those
discussed in The Hydroclone, D. Bradley, Pergamon
Press, Ltd. 1965 may be utilized in this context.
The solid phase resulting from the hydroclone separation
may be further processed, as desired, for the
recovery ofelemental sulfur and for the further processing
of the residue to recover any desired metal values
therefrom. The elemental sulfur can be recovered by
well known processes, such as solvent extraction, flotation,
and autoclave size enlargement. The hot brine
leach treatment, when conducted above the melting
15 point of sulfur, leaves the sulfur in a form more amenable
to physical separation techniques.
The liquid phase from this brine leach, containing the
lead chloride, is further processed for the removal of
the lead chloride. Preferably the lead chloride is crystallized
from the solution. When the pressure brine leach
technique is eMployed, substantial crystallization occurs
as a result of the reduction of the system pressure
to atmospheric pressure, and further crystallization
occurs by means ofreducing the solution temperature
and/or evaporating the solvent. The solution is preferably
vacuum cooled to about 40· ,C., which reduces the
lead chloride concentration in solution to about 15
grams per liter.
The resulting solid lead chloride cake can then be
reduced to elemental lead by various techniques. A
particularly preferred technique is to employ hydrogen
.reduction according to the general reaction:
4,276,084
5
When the final elemental lead product is produced by
meaas of hydrogen reduction, hydrochloric acid is a
necessary by-product. This hydrochloric acid serves as
a convenient source for the oxidation regeneration reaction,
and can be obtained by means of scrubbing the 5
hydrogen reduction furnace off-gas. The regenerated
cupric chloride leach solution is then recycled to the
leach phase of the process.
A portion ofthe separated.leach liquor from the leach
stage may be treated in order to remove impurities as 10
necessary in order to prevent excessive solution concentrations
of these values. Techniques known to the art,
such as cementation, electrolysis, chemical treatment,
pH adjustment, and others can be employed, as appropriate,
to remove the impurities.
The solids from the cupric chloride leach reaction,
compnsing lead chloride, elemental sulfur, unreacted
metal sulfides and gangue, are then preferably treated
for the separation of lead chloride. The lead chloride is
preferably solubilized from the residue, and a particu- 20
larly preferred technique in this respect is the use of a
brine leach mechanism. This brine leach is preferably
conducted with a brine solution having a sodium chloride
concentration offrom about 200 to about 300 grams
per liter, and more preferably from about 210 to about 25
250 grams per liter. In addition to or in place of sodium
chloride other chlorides such as calcium chloride, magnesium
chloride, lithium chloride and potassium chloride
may be employed in the solution.
The brine leach is preferably conducted at a tempera- 30
ture in excess of the solution boiling temperature,
which, of course, requires a pressurized system. The
temperature is preferably maintained from about 100·
C. to about 170· C., and more preferably from about
120· C. to about ISO· c., and the system pressure is 35
preferably selected so as to accommodate the solution
temperature while preventing solution boiling. Pressures
from about 30 to about ISO psig are suitable to
accomplish this purpose, and the pressure is preferably
maintained from about 40 to about 60 psig. 40
This brine leach, conducted under the described temperatures
and pressures, accomplishes a relatively high
solubility of lead chloride in a relatively short period of
time, while leaving the elemental sulfur and unreacted
metal sulfides in the residue phase. Retention times of 45
from about 30 seconds to about 5 minutes are generally
adequate to dissolve lead chloride to solution concentrations
of at least about 130 grams per liter of lead.
Increased lead concentrations as a result of the high
temperature and pressure brine leach significantly facili- 50
tate further separation processing.
The brine leach may be conducted at lower pressures,
including atmospheric pressure, and lower temperatures.
However, pressures and temperatures lower than
those recited for the preferred range of the brine leach 55
will require more of tlte brine solution per pound lead
chloride and a longer retention time in order to solubilize
the leach .;hloride.
Following the brine leach, the pregnant lead chloride
solution is separated from the remaining residue. Con- 60
ventional separation techniques may be employed, unless
the preferred brine leaching technique of high temperature
and pressure are utilized during the leach. In
such cases, the solid-liquid separation must remain
under pressure in order to prevent flash crystallization 65
of the lead chloride from the solution. One preferable
technique to accomplish the separation while avoiding
flash crystallization is to employ small diameter hydro4,276,084
7
sufficient hydrochloric acid to maintain the pH at about
1.0. Test 5 involved the same conditions as Test 4 except
that the pH was allowed to remain from about 2 to
8
suIting solids were brine leached in accordance with the
procedure set forth in Example 1, and Table 2 presents
the resulting extractions.
TABLE 2
COMPARISON OF LEAD CONCENTRATE LEACHES,
CUPRIC AND FERRIC CHLORIDE SYSTEMS
Lead Concentrate Analysis, % Type of Time Temp. Extraction, %
Pb Zn Cu Fe S Leach (hr.) ('C) Pb Zn Cu Fe
72.8 1.16 0.61 3.2 14.0 Fe+3 1 60 96.7 5.5 2.9 ND
72.8 1.16 0.61 3.2 14.0 Fe+3 4 60 99.4 22.4 21.7 21
72.8 1.16 0.61 3.2 14.0 Cu+2 I 60 99.0 4.3 -304 1.8
25.1 9.57 0.36 16.3 28.7 Fe+3 4 60 99.6 10.9 23.4 ND
25.1 9.57 0.36 16.3 28.7 Cu+z 3 60 99.4 1.6 -121 0.7
12.4 7.53 2.9 30.4 41.5 Fe+3 4 60 99.3 18.4 14.0 ND
12.4 7.53 2.9 30.4 41.5 Cu+z 3 60 99.6, 4.6 -39.8 1.0
NO = Not Determined
about 2.5 during the leach. Test 6 was conducted the
same as Test 4, except that the temperature was lowered 20
to 60° C. In Test 7, the Test 4 conditions were followed
except that the leach time was increased to three hours.
Tests 8 and 9 employed the same conditions as Test 7
except that in Test 8 concentrate B was leached and in
Test 9 concentrate C was leached. 25
Following each of the leaches the remaining solids
were leached in a brine solution at 85° C. and about
atmospheric pressure for 30 minutes, and the results of
this extraction are set forth in Table 1 as "Leach Results-
Extraction Percent", the percentage being based 30
upon initial concentrate weights. The negative copper
percentages reported are due to a portion of the cupric
chloride of the leach solution being precipitated as copper
sulfide.
EXAMPLE 3
Different 100 gram samples of a lead concentrate
having a composition of 18 percent lead, 26.2 percent
zinc, 0.54 percent copper, 5.1 troy ounces of silver per
ton of concentrate,' 0.029 percent antimony and 14.4
percent iron were treated with 250 milliliters of a cupric
chloride leach solution comprising about 50 grams of
copper per liter as cupric chloride and 200 grams of
sodium chloride per liter. The pH of the leach solution
was maintained at about 1 through the addition of hydrochloric
acid. After 3 hours, a total of 4.08 and 4.80
grams of hydrochloric acid were added to Sample 1and
Sample 2, respectively. The cupric chloride leach of
Sample I was conducted at a temperature of 60° C. and
the cupric chloride leach of Sample 2 was conducted at
TABLE I
3.3 4.3 5.4
1.6 0.7 45.6
4.6 1.0 134.0
3.3 3.9 19.7
Brine
Leach Results Leach
Extraction, % Residue
Pb Cu Zn Fe (grams)
60.8 0.0 8.7 3.2 43.6
93.9 6.7 16 0.0 40.5
76.8 99.8 19.2 7.3 69.2
99.0 -304 4.3 3.8 6.1
94.6 -107 4.2 2.5 4.7
60 88.4 -135
180 98.0 -312
180 99.4 -121
180 98.9 -39.8
60
60
60
60
200
200
200
200 60 60
200
200 90-95 145
200 85-90 60
137 85-90 60
133 90 220
47.5 30
with 02
48 ::::4.5
pH 1.0
47 ::::3.8
pH 2-
2.25
47 ::::4.8
pH 1.0
60 ::::5.2
47 ::::3.4
47 ::::5.4
Test Feed Fe+z
I. A
2. A 100
withOz
3. A
4. A
5. A
6. A
7. A
8. B
9. C
Leach Solution
___---'L~i~xi-"vi""an~t...::S~p:::ec""ie~s,wg:;:;m"'II_'__ Temp. Time
Cu+1 Cu+2 HCI NaCI ('C.) (min.)
EXAMPLE 2
Metal extraction percentages are presented for both
ferric chloride and cupric chloride leaches using three 60
different feed materials. The ferric chloride leach maintained
a ferric to ferrous ratio in grams per liter of about
9: 1. The leach was conducted with 20 percent solids and
a pH of less than 0.5. The cupric leaches were carried
out with a solution of about 50 grams of copper per liter 65
as cupric chloride, 10 percent solids, 5 grams hydrochloric
acid per liter and 230 grams sodium chloride per
liter, and the pH was maintained at about 1.0. The rea
temperature of 80° C. The residue of the cupric chloride
leach of each of the samples was separately brine
leached in a brine solution containing about 250 grams
of sodium chloride per liter at a temperature of 80°-85°
C. and about one atmosphere for one-half hour. Each
brine leach slurry was filtered while hot and the residue
was washed first with hot brine solution and then with
water. The analyses of the brine leach residue and the
results of this extraction are set forth in Table 3. The
negative extracted copper percentages are due to a
portion of the cupric chloride of the leach solution
being precipitated to copper sulfide.
9
4,276,084
10
TABLE 3
Cupric
Leach Brine Leach Residue Assay, % Extraction, %
Time Weight Ag
(Hours) Product (gm) Pb Zn Cu Fe (oz/ton) Sb Pb Zn Cu Fe Ag Sb
Sample I:
1.0 1 hr. 4.32 0.49 36.1 0.78 20.8 1.4 0.013 98.3 11.8 7.9 7.6 82.4 71
residue
3.0 Final 50.7 0.11 36.1 0.96 20.0 1.8 0.014 99.6 18.7 -4.5 18.1 79.2 72
residue
Sample 2:
1.0 1 hr. 4.43 0.10 37.4 0.98 19.8 1.2 0.018 99.6 7.2 -17.5 10.6 84.7 60
residue
2.0 2 hr. 4.52 0.08 36.7 1.00 19.2 1.1 0.011 99.7 17.4 -8.9 21.3 87.3 78
residue
3.0 Final 48.3 0.06 36.2 1.44 19.8 1.2 0.015 99.8 22.6 -49 23.0 86.8 71
residue
Example 10
A 100 gram sample of a lead concentrate having the
same composition as the sample of Example 5 was
Fe
TABLE 4
Cu Zn
0.805
Pb
0.21
from the feed are given below in Table 5. The negative
Example 4 extracted copper values of Examples 5-13 are due to a
A 125 gram sample of a lead concentrate having a 20 portion of the cupric chloride of the leach solution
composition of25.1 percent lead, 9.57 percent zinc, 0.36 being precipitated to copper sulfide.
percent copper and 16.3 percent iron was treated with
500 milliliters of a cupric chloride leach solution com- Example 6
prising about 50 grams of copper per liter as cupric A 100 gram sample of a lead concentrate having the'
chloride, 200 grams of sodium chloride per liter and 25 same composition as the sample of Example 5 was
sufficient hydrochloric acid to maintain a pH of about 1. milled for one-half hour in a ceramic pebble mill. The
The cupric chloride leach was conducted at a tempera- milled concentrate was then treated the same as the
ture of 60° C. for 2 hours. The residue of the cupric concentrate in Example 5. The assay of the brine leach
chloride leach was subjected to a 900 milliliter brine residue and percent metals extracted from the concenleach
at a temperature of 80°-90. C. and about atmo- 30 trate are given below in Table 5.
sphe~c pressure for one-half ho~r. The br:me solu~ion E 1 7
contamed about 250 grams of sodium chlonde per lIter. xamp e
The analysis of the brine leach residue, which weighed A 100 gram sample of a lead concentrate having the
83 grams, and the results of the extraction are set forth same composition as the sample of Example 5 was
in Table 4. 35 treated with 250 milliliters of a cupric chloride leach
The extraction resulted in 19.0 grams oflead chloride containing about 50 grams of copper per liter as cupric
being produced. This lead chloride was reduced to lead chloride and 200 grams of sodium chloride per liter at a
in an atmosphere of 175 cubic centimeters per minute of temperature of 90.-95° C. for 1 hour. The pH of the
hydrogen, 75 cubic centimeters per minute of carbon leach was maintained at about Iby the addition of hymonoxide,
75 cubic centimeters per minute of carbon 40 drochloric acid. The assay of the brine leach residue
dioxide at a temperature of 800° C. for 35 minutes. The and the percentage of metals extracted from the lead
lead metal was assayed by emission spectroscopy. The concentrate are given in Table 5.
lead metal was 99.98 percent pure. It contained impurities
of 0.01 percent silicon, 0.005 percent iron, 0.001
percent copper and 0.001 percent bismuth with no other 45
elements being detected.
Example 5
A 100 gram sample of a lead concentrate was treated
with 250 milliliters of a cupric chloride leach solution 60
comprising about 50 grams of copper per liter as cupric
chloride and 200 grams of sodium chloride per liter.
The cupric chloride leach was conducted at a temperature
of 40· C. for 4 hours with the pH of the leach being
maintained at about 1by the addition of about 4.1 grams 65
of hydrochloric acid throughout the leaching period.
The initial composition of the feed, assay of the brine
leach residue and the percentage of metals extracted
Example 8
A 100 gram sample of a lead concentrate having the
same composition as the sample of Example 5 was
milled for one-half hour in a ceramic pebble mill and
then treated exactly the same as the sample of Example
Brine Leach Residue Assay, % 7. The results are given in Table 5.
Ag SO
(oz/ton) Sb Example 9
13.9 22.8 2.0 0.33 A 100 gram sample of a lead concentrate having the
Extraction, %
Pb Cu Zn Fe Sb same composition as the sample of Example 5 was
Ag treated with 250 milliliters of a cupric chloride leach
--9-94'---~_-4-8-.5=.:.:36':..-_.:7.:..1:......_-=..:8.1:.:6.....__-=32=-_ 55 solution containing about 10 grams of copper per liter as
cupric chloride and 200 grams of sodium chloride per
liter at a temperature of 60° C. for 3 hours. The leach
solution was subjected to an air sparge of 1 liter per
minute to regenerate cupric ions from cuprous ions. The
pH of the leach solution was maintained at about 1.0 to
1.2. The lead concentrate was gradually added to the
leach solution in order to maintain an oxidizing emf of
the slurry at greater than 350 millivolts.
Results are given below in Table 5.
4,276,084
11 12
milled for one-half hour in a ceramic pebble mill and due and the percentage of metals extracted from the
then treated with 250 milliliters of a cupric chloride lead concentrate are given below in Table 5.
leach solution containing about 50 grams of copper per
liter as cupric chloride and 200 grams of sodium chlo- Example 13
ride per liter at a temperature of 40° C. for 4 hours. The 5 A 50 gram sample of a lead concentrate having the
pH of the leach solution was maintained at about 1.6 by same composition as the sample of Example 5 was
the addition of hydrochloric acid. The assay of the brine milled for one-half hour in a ceramic pebble mill and
leach residue and the percent metals extracted from the then treated with 125 milliliters of a cupric chloride
lead concentrate are given below in Table 5. leach solution containing about 10 grams of copper per
Example 11
10 liter as cupric chloride and 200 grams of sodium chloride
per liter at 50° C. for 4.5 hours. Throughout the
A 50 gram sample of a lead concentrate having the course of the leach, the leach solution was subjected to
same composition as the sample of Example 5 was an air sparge of 1 liter per minute and the pH of the
milled for one-half hour in a ceramic pebble mill and solution was maintained at about 1.6 by the addition of
then treated with 125 milliliters of a cupric chloride 15 hydrochloric acid. The final emfof the slurry was +360
leach solution comprising about 10 grams of copper per millivolts. The assay of the brine .leach residue and
liter as cupric chloride and 200 grams of sodium chlo- percentage of metals extracted from the lead concenride
per liter at a temperature of 40° C. for 4 hours. The trate are given below in Table 5.
TABLE 5
Assay, %
Time Weight Ag Extraction, %
Ex. (Hrs.) Product (gm) Pb Zn Cu (oz/ton) Sb Fe Pb Zn Cu Ag Sb Fe
0 Feed 18.0 26.2 0.54 5.1 0.029 14.4
1 Residue 4.97 2.06 37.5 0.86 2.3 19.4 92 1.2 -9.9 69 7.0
2 Residue 4.68 1.85 36.3 0.83 2.3 20.0 93 9.9 0.1 71 9.7
4 Residue 53.0 1.36 36.5 0.89 2.3 0.010 20.2 95 15 -0.5 72 79 14
6 1 Residue 5.31 1.17 37.9 1.05 3.0 19.7 96 0.2 -34 59 5.6
2 Residue 4.89 0.47 38.0 1.45 1.6 19.4 98 4.3 -77 79 11
4 Residue 55.3 0.86 37.3 0.94' 2.3 0.070 20.6 97 8.9 -11 71 8.4
7 0.08 Residue 5.28 1.68 36.6 0.95 2.0 19.2 94 11 -12 75 15
0.16 Residue 3.89 1.16 34.3 1.02 2.2 20.6 96 20 -15 74 13
0.25 Residue 4.28 0.68 35.4 1.09 2.0 20.5 98 20 -19 77 16
1 Residue 44.6 0.065 36.1 1.49 1.3 0.080 19.7 99.8 21 -57 85 22
8 0.08 Residue 4.38 0.52 36.0 1.02 1.5 19.9 98 15 -17 82 14
0.16 Residue 4.13 0.16 35.3 0.91 1.2 20.0 99.5 19 -1.1 86 17
0.28 Residue 4.42 0.075 36.9 1.10 1.2 19.3 99.8 18 -18 86 22
1 Residue 46.3 0.043 35.8 1.64 1.3 0.038 19.7 99.9 21 -76 85 24 21
9 3 Residue 62.2 2.40 31.4 0.96 1.8 0.018 19.9 91.7 26 -11 78 14
10 1 Residue 5.59 1.36 38.4 0.86 2.5 20.4 95 0.3 -8.3 67 3.7
2 Residue 5.38 1.11 39.2 0.88 2.4 20.9 96 1.2 -7.6 69 4.2
4 Residue 55.1 1.06 39.4 0.91 2.1 0.024 21.4 96 2.2 -9.5 73 46 3.4
11 4 Residue 33.3 1.30 39.8 0.83 2.4 0.029 21.5 95 0.0 0.0 69 33 0.6
12 4.5 Residue 37.0 4.74 35.4 0.81 5.0 0.027 20.1 80 0.0 -11 27 31 0.0
13 4.5 Residue 32.7 1.84 35.6 0.89 2.2 0.023 21.0 93 11.1 -7.8 72 48 4.6
leach solution was subjected to an air sparge of 1 liter
per minute throughout the leaching process. The pH of 45
the leach solution was maintained at about 1.6 by the
addition of hydrochloric acid. The lead concentrate
feed was added to the leach solution over the course of
the leach in order to maintain an oxidizing emf of the
slurry at greater than or equal to 350 millivolts. 50
The assay of the brine leach residue and the percent
metals extracted from the lead concentrate are given
below in Table 5.
Example 12. 55
A 50 gram sample of a lead concentrate having the
same composition as the sample of Example 5 was
milled for one-half hour in a ceramic pebble mill and
then treated with 125 milliliters of a cupric chloride
leach solution containing about 10 grams of copper per 60
liter as cupric chloride and 20 grams of sodium chloride
per liter at a temperature of 40° C. for 4.5 hours.
Throughout the course of the leach, the leach solution
was subjected to an air sparge of 1 liter per minute. The
pH of the leach solution was maintained at about 1.6 65
and the feed was added over the course of the leach in
order to maintain an oxidizing emf of the slurry at 350
millivolts or greater. The assay of the brine leach resi-
What is claimed is:
1. A process for obtaining lead chloride from sulfide
ores containing lead sulfide comprising:
(a) leaching the ore with an aqueous solution containing
cupric chloride under reaction conditions of
temperature, time, pH, an oxidizing emf, total copper
concentration and total chloride ion concentration
selected so as to convert a substantial portion
of the lead sulfide to lead chloride while leaving
the remainder of the ore substantially unreacted
and wherein the cupric chloride leach solution
does not solubilize all of the lead chloride so that a
portion of the lead chloride precipitates from the
leach solution; and
(b) separating solids comprising lead chloride, unreacted
ore, sulfur and gangue from the leach solution.
2. A process for separating lead chloride formed from
sulfide ores containing lead sulfide comprising:
(a) leaching the ore with an aqueous solution containing
cupric chloride under reaction conditions of
temperature, time, pH, an oxidizing emf, total copper
concentration and total chloride ion concentration
selected so as to convert a substantial portion
of the lead sulfide to lead chloride while leaving
the remainder of the ore substantially unreacted
4,276,084
13
and wherein the cupric chloride leach solution
does not solubilize all of the lead chloride formed
so that a portion of the lead chloride precipitates
from the leach solution;
(b) separating solids comprising lead chloride, unre- 5
acted ore, sulfur and gangue from the leach solution;
(c) subjecting the separated solids to a brine leach at
a temperature of from about 100° C. to about 170°
C. and a pressure of from about 30 p.s.i.g. to about 10
150 p.s.i.g. in order to substantially solubilize the
lead chloride to the exclusion of the other solids;
(d) separating the brine leach solution containing the
solubilized lead chloride from the solids; and
(e) separating the lead chloride from the brine leach 15
solution separated in step (d).
3. The process of claim 1 or ciaim 2 wherein the
cupric chloride leach solution solubilies less than about
10 percent of the lead chloride formed.
4. The process of claim 1 or claim 2 wherein the 20
cupric chloride of the leach solution ofstep (a) is regenerated
by sparging the leach solution with a source of
oxygen.
5. The process of claim 4 wherein the cupric chloride
leach solution separated in step (b) is recycled back to 25
step (a).
6. The process ofclaim 1 or claim 2 wherein a portion
of the cupric chloride leach solution of step (a) is removed,
treated to remove the dissolved metal chlorides
contained therein and thereafter the treated cupric chlo- 30
ride leach solution is returned to step (a).
7. The process of claim 1 or claim 2 wherein the
cupric chloride leach of the ore is conducted at a temperature
of from about 30° to about 95° C. and a pH
between about 0.5 and 4, wherein the cupric chloride 35
leach solution contains from about 3 to about 100 grams
of copper in solution per liter of the leach solution and
wherein the cupric ion to cuprous ion ratio of the leach
solution is maintained within a range of from about 1:20
to about 16:1. 40
8. The process of claim 7 wherein the leach solution
emfis maintained from about 200 to about 500 millivolts
so as to cause the formation of elemental sulfur from the
sulfide sulfur contained within the ore.
9. The process of claim 7 wherein the chloride ion 45
concentration of the cupric chloride leach solution does
not substantially exceed the amount needed to keep the
copper in solution and wherein the chloride ion concentration
is maintained by the addition of a monovalent,
water soluble, chloride salt in an amount containing 50
from about 0.85 moles to about 5 moles of chloride.
10. A process of forming lead chloride from sulfide
ores containing lead sulfide comprising:
(a) leaching the ore with an aqueous solution containing
cupric chloride and saturated with lead chlo- 55
ride at a temperature of from about 30° C. to about
95° C. and a pH of from about 0.5 to about 4,
wherein the cupric chloride leach solution contains
from about 3 to about 100 grams of copper in solution
per liter of leach solution, and less than about 60
20 grams of hydrochloric acid per liter of leach
solution, and wherein the cupric chloride leach
solution has a chloride ion concentration not substantially
exceeding the amount of chloride ion
needed to keep the copper in solution with the 65
chloride ion concentration being maintained by the
addition of a monovalent, water soluble, chloride
salt in an amount containing from about 0.85 moles
14
to about 5 moles of chloride per liter of leach solution,
has a cupric ion to cuprous ion ratio maintained
in the range of about 1:20 to about 16:1 and
has an oxidizing emf, so as to convert a substantial
portion of the lead sulfide to lead chloride while
leaving the remainder of the ore substantially unreacted;
(b) separating solids comprising lead chloride, unreacted
ore, sulfur and gangue from the leach solution.
11. A process for separating lead chloride formed
from sulfide ores containing lead sulfide comprising:
(a) leaching the ore with an aqueous solution containing
cupric chloride and saturated with lead chloride
at a temperature of from about 30° C. to about
95° C. and a pH of from about 0.5 to about 4,
wherein the cupric chloride leach solution contains
from about 3 to about 100 grams of copper in solution
per liter of leach solution and less than about
20 grams of hydrochloric acid per liter of leach
solution, and wherein the cupric chloride leach
solution has a chloride ion concentration not substantially
exceeding the amount of chloride ion
needed to keep the copper in solution with the
chloride ion concentration being maintained by the
addition of a monovalent, water soluble, chloride
salt in an amount containing-from about 0.85 moles
to about 5 moles of chloride per liter of leach solution,
has a cupric ion to cuprous ion ratio maintained
in the range of about 1:20 to about 16:1 and
has an oxidizing emf, so as to convert a substantial
portion of the lead sulfide to lead chloride while
leaving the remainder of the ore substantially
ureacted;
(b) separating solids comprising lead chloride, unreacted
ore, sulfur and gangue from the leach solution;
(c) subjecting the separated solids to a brine leach at
a temperature from about 100° C. to about 170° C.
and a pressure of from about 30 p.s.i.g. to about 150
p.s.i.g. in order to substantially solubilize the lead
chloride to the exclusion of the other solids;
(d) separating the brine leach solution containing the
solubilized lead chloride from the solids; and
(e) separating the lead chloride from the brine leach
solution separated in step (d).
12. The process ofclaim 11 wherein the brine leach of
step (c) contains from about 200 to about 300 grams of
sodium chloride per liter.
13. The process of claim 10 or claim 11 wherein the
cupic chloride contained in the leach solution of step (a)
is regenerated by sparging the leach solution with a
source of oxygen.
14. The process of claim 13 wherein a bleed stream is
taken from the leach solution of step (a), treated to
remove dissolved metal chlorides contained therein and
then returned to leach step (a).
15. The process of claim 10 or claim 11 wherein the
cupric chloride leach solution has a pH of from about
0.5 to about 2 and the cupric chloride leach is conducted
at a temperature of from about 30' C. to about
75° C., wherein the cupric chloride leach solution contains
from about 5 to about 50 grams of copper in solution
per liter ofleach solution and from about 1 to about
10 grams of hydrochloric acid per liter ofleach solution
and wherein the cupric chloride leach solution has a
chloride ion concentration not substantially exceeding
the amount of chloride ion needed to keep the copper in
* * * * >I<
16
60° C. and a pH of from about 0.5 to about 2,
wherein the cupric chloride leach solution contains
from about 8 grams to about 25 grams of copper in
solution per liter of leach solution and from about 3
grams to about 7 grams of hydrochloric acid per
liter of leach solution and wherein the cupric chloride
leach solution has a cupric ion to cuprous ion
ratio of from about 1:5 to about 3:1, has an emf of
from about 350 to about 400 millivolts and has a
chloride ion concentration not substantially exceeding
the amount of chloride ion needed to keep
the cooper in solution with the chloride ion concentration
being maintained by the addition of
sodium chloride in an amount of from about 100
grams to about 250 grams of sodium chloride per
liter of leach solution, so as to convert a substantial
portion of the lead sulfide to lead chloride while
leaving the remainder of the ore substantially unreacted;
and
(b) separating the solids comprising lead chloride,
unreacted ore, sulfur and gangue from the leach
solution;
(c) subjecting the separated solids to an aqueous brine
leach containing from about 210 to about 250
grams of sodium chloride per liter of leach at a
temperature offrom about 120° C. to about 150° C.
and a pressure of from about 40 p.s.i.g. to about 60
p.s.i.g. in order to substantially solubilize the lead
chloride to the exclusion of the other solids;
(d) separating the brine leach solution containing the
solubilized lead chloride from the solids; and
(e) crystallizing the lead chloride from the separated
brine leach solution of step (d).
20. The process of claim 18 or claim 19 wherein the
cupric chloride contained in the leach solution of step
(a) is regenerated by sparging the leach solution with a
source of oxygen, wherein a bleed stream is taken from
the leach solution of step (a), treated to remove dissolved
metal chlorides contained therein and then returned
to leach step (a) and wherein at least a portion of
cupric chloride leach solution is comprised of the separated
leach solution of step (b).
21. The process of claim 20 wherein the crystallized
lead chloride of step (e) is reduced to obtain elemental
lead.
15
4,276,084
15
solution with the chloride ion concentration being
maintained by the addition of a monovalent, water soluble,
chloride salt in an amount containing from about
1.7 moles to about 4.3 moles of chloride per liter of
leach solution, has a cupric ion to cuprous ion ratio of 5
from about 1:9 to about 4:1 and has an emf of from about
250 to about 450 millivolts. .
16. The process of claim 15 wherein the chloride ion
concentration is maintained by the addition of from
about 100 grams to about 250 grams of sodium chloride 10
per liter of cupric chloride leach solution.
17. The process of claim 10 or claim 11 wherein at
least a portion of the cupric chloride leach solution
saturated with lead chloride is supplied from the separated
leach solution of step (b).
18. A process of forming lead chloride from sulfide
ores containing lead sulfide comprising:
(a) leaching the ore with an aqueous solution containing
cupric chloride and saturated with lead chloride
at a temperature of from about 30° C. to about 20
60° and a pH of from about 0.5 to about 2, wherein
the cupric chloride leach solution contains from
about 8 grams to about 25 grams of copper in solution
per liter of leach solution and from about 3
grams to about 7 grams of hydrochloric acid per 25
liter of leach solution and wherein the cupric chloride
leach solution has a cupric ion to cuprous ion
ratio of from about 1:5 to about 3:1, has an emf of
from about 350 to about 400 millivolts and has a
chloride ion concentration not substantially ex- 30
ceeding the amount of chloride ion needed to keep
the copper in solution with the chloride ion concentration
being maintained by the addition of
sodium chloride in an amount of from about 100
grams to about 250 grams of sodium chloride per 35
liter of leach solution, so as to convert a substantial
portion of the lead sulfide to lead chloride while
leaving the remainder of the ore substantially unreacted;
and
(b) separating the solids comprising lead chloride, 40
unreacted ore, sulfur and gangue from the leach
solution.
19. A process of separating leach chloride formed
from sulfide ores containing lead sulfide comprising:
(a) leaching the ore with an aqueous solution contain- 45
ing cupric chloride and saturated with lead chloride
at a temperature of from about 30° C. to about
50
55
60
65
tX��op@s� >smaltite.
48. The process of claim 38 wherein the sulfide ore is 65
tetrahedrite.
49. The process of claim 30 wherein the gas is nitrogen
and the ore is galena.
• • • • •
18
cite, chalcopyrite, orpiment, pentlandite, stibnite and
tetrahedrite.
67. The process of claim 66 wherein the sulfide ore is
galena.
68. The process of claim 66 wherein the sulfide ore is
stibnite.
69. The process of claim 66 wherein the sulfide ore is
bornite.
70. The process of claim 66 wherein the sulfide ore is
chalcocite.
71. The process of claim 66 wherein the sulfide ore is
orpiment.
72. The process of claim 66 wherein the sulfide ore is
15 pentlandite.
73. The process of claim 66 wherein the sulfide ore is
cinnabar.
74. The process of claim 66 wherein the sulfide ore is
arsenopyrite.
75. The process of claim 66 wherein the sulfide ore is
smaltite.
76. The process of claim 66 wherein the sulfide ore is
tetrahedrite.
4,276,081
17
62. The process of claim 16 wherein the iron containing
compound is employed in an amount of from about
1 to about 50 kilograms per metric ton of ore and the
selective magnetic enhancement reaction is carried out
at a temperature within a range of 50' C. less than the 5
general decomposition temperature of the iron containing
compound in a specific system for the ore being
treated for a period of time from about 0.15 to about 2
hours.
63. The process ofclaim 62 wherein the iron contain- 10
ing compound is an iron carbonyl and the treatment
process is carried out at a temperature within a range of
15' C. less than the general decomposition temperature
of the iron carbonyl in the specific system for the ore
being treated.
64. The process of claim 62 wherein the mineral values
are physically separated from the gangue by a magnetic
separation process.
65. The process of claim 62 wherein the mineral values
are physically separated from the gangue by an 20
electrostatic technique.
66. The process of claim 35 wherein the sulfide ore is
selected from the group consisting of galena, molybdenite,
bornite, cinnabar, arsenopyrite, smaltite, chalco-
25
30
35
40
45
50
55
60
65