United States Patent [19]
Coltrinari
[11]
[45]
4,051,220
Sept. 27, 1977
[54] SODIUM SULFIDE LEACH PROCESS
[75] Inventor: Enzo L. Coltrinari, Arvada,· Colo.
[73] Assignee: Equity Mining Corporation,
Vancouver, Canada
OTHER PUBLICATIONS
Remy, Treatise on Inorganic Chemistry, vol. I, Elsevier
Pub. Co., N. Y., 1956, pp. 659, 660.
Primary Examiner-D. R. Vertiz
Assistant Examiner-Brian Hearn
[21] Appl. No.: 662,583
[51] Int. Cl.2 COIG 7/00; COlO 57/00
[52] U.S. Cl 423/24; 423/27;
423/87; 423/511
[58] Field of Search 423/24, 37, 87, 511,
423/561, 27; 75/101 BE, WI R, 118
[22] Filed:
16 Claims, I Drawing Figure
[57] ABSTRACf
A process is disclosed for treating mixed metal sulfides
containing trivalent antimony sulfide wherein the .sulfide
concentrates are leached with an excess of sodium
sulfide in order to isolate copper sulfide and other insolubles
in solid form while solubilizing the remaining
metal sulfides and producing sodium thioantimonite,
separating the insoluble sulfides from the solution; oxidizing
the sodium thioantimonite with elemental sulfur
to produce sodium thioantimonate in solution; crystallizing
a portion of the sodium thioantimonate along
with other available metal sulfides from solution; and
recirculating the remainder of the solution to the sodium
sulfide leach stage. The crystallized metal sulfides
may be further treated, isolated, and recovered as desired.
Mar. 1, 1976
References Cited
U.S. PATENT DOCUMENTS
6/1883 Parsons 423/87
6/1902 Van der Ploeg 423/87
8/1972 Moore 423/24
10/1975 Nadkarni 423/87
278,816
702,153
3,682,589
3,911,078
[56]
FILTER---.RECYCLE TO LEACH
SULFIDE
CONCENTRATE
HIGH IN
ARSENOPYRITE
Au/CHARCOAL
SULFIDE
COf'£ENTRATE
LOW IN
ARSENOPYRITE
~
~
(Da
c..en
IV
....,J -\0
....,J
....,J
en .g...
+::-.
'IIo
Ul
~
'"NNo
f SULFIDE SULFIDE
CONCENTRATE CONCENTRATE 02-- AUTOCLAVE
LOW IN HIGH IN OXIDATION
ARSENOPYRITE ARSENOPYRITE (NoOH)-- (PARTIAL)
t
S°--r ROAST FI LTRATION ::
t ~S I IN02S
~ LEACH •U 'SCRUBBER" H2S As/Sb SULFIDE
PRECIPITATION ~H2S04
f
FI LTRATION li--=H20 N1H ~
H2S<?4, ACIDIFICATION H2 S
TO pHS
FI LTER
EVAPORATION H2O t t II
FILTER II I--H2O EVAPORATIO N
~
AIR a ROAST f--S02
CRYSTALLIZATION I a S/L SEPARATION
CARBON t t FURNACE
BLEED: Cu/Ag SULFIDE t RESIDUE t,
CRYSTAL
No2S
.. DISSOLUTION a H2S- TO LEACH ACIDI FICATION
TO pH 12
FILtER--_RECYCLE TO LEACH
,
ISb SULFIDE~ Au RECOVERY n -: Au/CHARCOAL I Hg/Si As/Sb
PRECIPITATE SULFIDES
f
SO
(No
H2 SO.
H20
BRIEF DESCRIPTION OF THE DRAWING
The FIGURE represents a process flow diagram
incorporating the sodium sulfide leach and crystallization
phase of the process, as well as the subsequent
treating stages to recover gold, mercury and antimony.
DESCRIPTION OF THE PREFERRED
EMBODIMENTS
2
timonate from solution, separating the crystallized values
from the remaining solution, and recirculating the
remaining solution to· the sodium sulfide leach stage.
When substantial portions of arsenopyrite are present in
5 the initial concentrate, the concentrate is preferably
roasted prior to the sodium sulfide leach stage. The
crystals from the crystallization stage may be dissolved
and further treated for recovery of the various metal
values, including, for example, gold, mercury, and antimony.
4,051,220
1
SUMMARY OF THE INVENTION
SODIUM SULFIDE LEACH PROCESS
BACKGROUND OF THE INVENTION
1. Field of the Invention
The process of the present invention relates generally
to hydrometallurgical chemical leaching, as classified in
Class 75, subclass IOIR; and in one preferred embodiment
relates to the treating of a mixture to obtain an
antimony-containing compound as classified in Class 10
423, subclass 87.
2. The Prior Art
A number of sulfide mineral ore bodies exist which
possess a considerable amount of antimony values.
These antimony values may be existent in several forms, 15
including tetrahedrite and stibnite. Often they exist in
association with other mineral values, such as chalcopyrite.
While no processes are known which deal directly
with recovering antimony values from mixed metal
sulfides, several are known for treating concentrates 20 The starting materials for this process include mineral
possessing relatively large amounts of arsenic values, sulfides with at least some trivalent antimony sulfide.
including U.S. Pat. No. 3,709,680 to Holmes and CoI- The primary trivalent antimony sulfide minerals include
trinari, and U.S. Pat. No. 3,911,078 to Nadkami et al. tetrahedrite and stibnite. Examples of other mineral
Holmes and Coltrinari disclose a process for removing sulfides ·which may exist with the antimony sulfides
arsenic from its ore concentrates by leaching the con- 25 include chalcopyrite, pyrite, sphalerite, galena, pyrrhocentrates
with an alkali metal sulfide to dissolve the tite, enargite, arsenopyrite, chalcocite, and other wellarsenic
values, precipitating the arsenic values from the known metal sulfide values. The amount of antimony
solution by acidification, discarding the resultant ar- sulfide in the initial feed composition is not important,
senic values, and further treating the remaining solution as long as that amount is sufficient for recovery in an
in order to regenerate the alkali metal sulfide. 30 economical fashion or to at least necessitate removal as
The Nadkami reference discloses a process designed an impurity during the recovery of one or more of the
to remove essentially all of the arsenic from copper other metal values.
sulfide ores by leaching the concentrates with sodium The mineral values are preferably concentrated and
sulfide in the presence of sodium hydroxide or other properly sized in order to facilitate the leaching process.
hydroxyl group in order to produce sodium thioarsen- 35 The many techniques for accomplishing these proceate
and sodium thioantimonate. The arsenic values, dures are, of course, well known in the art.
along with any antimony present, are then crystallized The leach phase of the process dissolves many of the
from the solution and discarded, and the sodium sul- mineral values, including the antimony sulfides, while
fide/sodium hydroxide solution is then recirculated to leaving certain values, such as copper and silver, in
the leaching step. 40 solid sulfide form. This permits ready separation of the
It is observed that the Nadkarni process is well suited solids from solution, and these solid sulfide values may
for its purpose when dealing with sulfide ores contain- then be further processed as desired. Examples of metal
ing arsenic in its pentavalent form. This highly oxidized sulfides which would not be dissolved by the sodium
form of arsenic produces sodium thioarsenate in accor- sulfide leach reaction of this process include copper
dance with the reactions presented in the reference, and 45 sulfides, silver sulfides, zinc sulfides. and lead sulfides.
this sodium thioarsenate may then be crystallized from The leaching phase is preferably conducted with a
solution. However, it has been observed that when sodium sulfide solution in order to dissolve such metal
antimony and arsenic are present in the initial concen- sulfides as antimony, arsenic, mercury, and some of the
trate in their trisulfide forms, the Nadkami process is gold. The leach is preferably conducted at a temperanot
as effective. 50 ture of from about 60° C to about 150° C, more prefer-
The process of the present invention separates anti- ably from about 75° C to about slightly less than the
mony and arsenic from their concentrates, even when boiling temperature of the solution, and most preferably
these values are in their trisulfide forms. Furthermore, from about 85° C to about 110° C. The reaction time is
in a preferred embodiment of the present process, a primarily .a function of temperature, grind, and the
method is disclosed for the ultimate recovery of anti- 55 amount of sodium sulfide present, and generally at a
mony. temperature of about 100° C and a substantial excess of
sodium sulfide present, times from about 0.5 hours to
about 24 hours are acceptable, with preferable times
being from about 4 to 8 hours.
Other acceptable leaching agents include potassium
sulfide, and when the antimony sulfide is primarily stibnite,
ammonium sulfide. For simplicity of discussion,
the sodium sulfide system will be described herein, but
it is observed that similar values are also applicable to
these other leaching agents.
The stoichiometric amount ofsodium sulfide required
to complete the leaching phase of the process is dependent
upon the composition of the starting materials. A
A process is disclosed for treating metal sulfide ores
and concentrates containing trivalent antimony sulfide 60
comprising essentially the steps of leaching and concentrates
with sodium sulfide in order to produce solid
copper and other insoluble metal sulfides and a solution
comprising sodium thioantimonite and the remaining
metal sulfide values, separating the solid copper and 65
other insolublesfrom the solution, oxidizing the sodium
thioantimonite in solution to sodiumthioantimonate,
crystallizing a substantial portion ofthe sodium thioanFeS2'
FeA~ + 4S -> 2FeS2 + 2AsS
wherein R is a mixture ofCland ClOcarbon chains, with
the CI predominating. One particularly preferable example
of this ion exchange agent is a tricaprylyl monomethyl
ammonium chloride, which compound is available
from the General Mills corporation under the trade
name "ALIQUAT 336."
This ion exchange agent is preferably loaded onto an
activated carbon carrier and brought into contact with
the gold-bearing stream in order to adsorb the gold.
The feed stream pH is preferably adjusted to about 12,
which is conveniently accomplished by the addition of
4
about 18· C from about SO' C,generally about 85 percent
of the sodium thioantimonate in solution is crystallized.
Another preferable crystallization technique is
vacuum evaporation, and of course this method does
5 not require such cool temperatures.
Following the crystallization step, the solution comprises
primarily sodium sulfide, with some residual
metal sulfide values. This stream may then be recirculated,
without the necessity of any additional process-
10 ing, to the sodium sulfide leach step for the processing
of additional feed materials.
Certain metal sulfides present in the feed material may
necessitate initial processing prior to being introduced
into the leach stage. An example of such a material is
arsenopyrite, and when this mineral is present in a significant
amount it is desirable to initially roast the concentrate
in order to decompose the arsenopyrite. This
decomposition reaction is believed to be as follows:
These products may then be treated by the sodium
sulfide leach phase of the process. This roast may be
conducted in a conventional manner, such as described
in British patent specification No. 997,331, and within a
temperature range of preferably from about 300· C to
about 700' C, more preferably from about 400' C to
about 600' C, and most preferably from about 480' C to
about 520' C. At a temperature of about 500' C, the
reaction time is generally within from about 0.5 to about
1.5 hours.
The crystals from the crystallization stage of the process
may be further treated in order to recover any
desired mineral values contained therein, as well as to
regenerate any residual sodium sulfide. The crystals are
preferably initially redissolved, and the solvent may
consist of a number of alternatives, including a portion
of the mother liquor sodium sulfide solution from the
crystallization stage. Other suitable solvents include the
40 antimony sulfide wash solution, when the antimony
recovery step is employed with the process, as well as
water and other downstream wash solutions.
When a significant amount of gold is in solution, this
gold may be conveniently removed at this stage of the
process. Various techniques may be employed, with one
preferable and novel technique employing an ion exchange
reaction.. Suitable ion exchange agents include
water insoluble quaternary amines of the following
formula:
(3)
(2) 15
(I)
4,051,220
3Na2S + 4CU2S.Sb2S3 (Tetrahedrite) -> 4CU2S +
2Na3SbS3
3Na2S + 3CU2S.A~S~ (Enargite) -> 3CU2S + 2Na).
AsS.
3
substantial excess of sodium sulfideis preferred in order
to insure complete dissolution of the desired metal sulfides
within a reasonable time. The sodium sulfide concentration
introduced to the leach step is therefore preferably
from about 50 to about 400, more preferably
from about 150 to about 350, and most preferably from
about 250 to about 300 grams per liter. As stibnite is
relatively easily dissolved, a lower concentration is
acceptable for its treatment.
The sodium sulfide leaching of antimony and arsenic
sulfides is in accordance with the following reactions:
(4)
20
As equations (I) and (2) indicate, the soluble antimony
products are sodium thioantimonite when the starting
materials contain trivalent antimony sulfides. Also, as
equation (3) indicates, when arsenic is present as a trivalent
arsenic sulfide, the resulting product is sodium 25
thioarsenite. Equation (4), on the other hand, discloses
that sodium thioarsenate is produced when the starting
material is in its pentavalent form, and this is in accordance
with U.S. Pat. No. 3,911,078 to Nadkarni. The
leach solution will also contain a substantial amount of 30
sodium sulfide, due to the excess of this composition in
the starting materials.
Following the leach reaction, it is important to convert
the sodium thioantimonite to sodium thioantimonate
by oxidatively reacting this composition with ele- 35
mental sulfur. The immediate removal of the arsenic
and antimony values from their leach solutions by
means of crystallization is ineffective in the absence of
this reaction, which proceeds as follows:
This reaction is preferably conducted within temperatures
of from about 20' C to about 200' C, more preferably
from about SO' C to about 100' C, and most prefer- 45
ably from about 60· C to about 80· C, with the reaction
times being sufficient to convert substantially all of the
sodium thioantimonite to sodium thioantimonate, which
is preferably from about 0.1 to about 10, and more preferably
from about 0.25 to about 0.5 hours. 50
Following this oxidation reaction, the antimony values
are crystallized from solution.
Portions of other metal sulfides in solution will crystallize
with the antimony values, including for example.
mercury sulfides and sodium thioarsenate. Some gold 55
may also crystalize. When trivalent arsenic sulfide is
present in the feed material, the sodium sulfide leach
reaction will convert this compound to sodium thioarsenite.
The subsequent sulfur oxidation reaction oxidizes
this value to sodium thioarsenate. 60
The crystallization technique may be in accordance
with conventional methods, such as evaporation and
refrigeration, as well as any suitable combination of
known techniques. The solution is preferably cooled to
at least about 40' C, more preferably to at least about 65
25' C, and most preferably to at least about 18' C.When
a solution containing about 200 grams per liter sodium
sulfide and SO grams per liter antimony is cooled to
4,051,220
5 6
sulfuric acid. Based on the total weight of the Aliquat or part of the arsenic will also be oxidized, and the
336 and activated carbon, about 10 percent Aliquat 336 antimony-arsenic separation will not be accomplished.
loaded onto about 90 percent by weight activated car- The preferred amount of oxygen consumed by the reacbon
and placed in a column yields about 0.3 percent by tion when the reactants are thioantimonate and thioarweight
gold (based on the total weight of activated S senate and there are no additional compounds competcarbon,
Aliquat 336, and gold) when the initial. feed ing for the oxygen is such that the final solution e.m.f. is
solution contains from about 2 to about 5 parts per preferably from about 300 to about 500, more prefermillion
gold and is percolated through the column. ably from about 350 to about 430, and most preferably
The temperature of this gold recovery process is from about 390 to about 410 millivolts, measured with
preferably from about 10° C to about 60° C, and more 10 Platinum/saturated Calomel electrodes. Based on this
preferably from about 20° C to about 35° C, with a criteria, it is generally found that the amount of oxygen
solution retention time in contact with the activated consumed per pound of antimony being treated is prefcarbon
of from about 0.1 to about 30 minutes. The gold erably from about 0.5 to about 1.5, more preferably
adsorbed onto the ion exchange agent may then be from about 0.6 to about 0.9, and most preferably from
recovered in conventional fashion. 15 about 0.75 to about 0.85 pounds. .
When mercury is present in the resulting solution, it, . It is also critical to the effective operation of the proalong
with silica, may be recovered by adjusting the pH cess that the pH be maintained within a range of about
of the solution to about 8, which again may be accom- 7 to about 11, more preferably from about 7.5 to about
plished by the addition of sulfuric acid. 10, and most preferably from about 8 to about 9. If the
Once the gold and mercury and other desired metal 20
values are removed, the solution will generally com- pH is permitted to fall below the minimum values, preprise
predominantly sodium thioarsenate and sodium cipitates other than antimony sulfides tend to be prothioantimonate.
Under many conditions, it is desirable duced, detrimentally affecting the product purity. The
to separate the antimony sulfides from the remainder of solution pH may be maintained by adding, if necessary,
the solution, as antimony has substantial commercial 2S any suitable base, such as sodium hydroxide.
value. The temperature and pressure of the reaction are not
A preferable and novel technique for recovering the particularly important from the final product standantimony
values from this resulting solution is by oxi- point, but do affect the rate of reaction. The reaction
dizing the thioantimonate compounds in solution in does proceed at room temperature and atmospheric
order to selectively precipitate these values as antimony 30 pressure, although the rate is quite slow. Therefore, the
sulfides, thereby separating these antimony values from reaction temperature is preferably maintained from
the arsenic values in solution. The thioantimonate com- about 25° C to about 200° C, more preferably from
pounds are reacted with oxygen in order to produce about 50° C to about 150° C, and most preferably from
insoluble antimony sulfides and under some circum- about 90° C to about 120° C. The reaction pressure is
stances possibly minor amounts of sodium hydroxyanti- 35 preferably maintained at at least about atmospheric
monate and sulfur, lilong with soluble arsenic com- pressure, more preferably from about 20 to about150,
pounds, soluble sodium thiosulfate and possibly some and'most preferably from about 40 to about 80 psig.
other non-sulfate sodium salt. Hence, the primary reac- The reaction time is very fast, and within the pertion
is believed to be: ferred temperature and pressure parameters set forth
40 above, the reaction time is not a factor. Hence, the
process. may conveniently be conducted in either a
batch or continuous fashion. It is generally preferred to
agitate the solution during the reaction in order to keep
the oxygen well dispersed.
As was previously mentioned, the antimony product
stream may be redissolved and recycled in order to
obtain an antimony sulfide product practically entirely
free of arsenic impurity.
Upon completion of the reaction, the product stream
is filtered in order to separate the antimony sulfide precipitate
from the product solution. The antimony sulfide
product is then of commercial value and may be sold at
this point, or further conventionally treated to produce
antimony oxide, elemental antimony, and other products.
The product solution may be further treated for
the production of any other values desired.
EXAMPLES
The following example illustrates the process of the
present invention for a feed material comprising essentially
about 35% chalcopyrite, 35% tetrahedrite, 10%
pyrite, 5% sphalerite, 4% galena, 3% pyrrhotite, 2%
arsenopyrite, minor amounts of other metal sulfide values
including gold and mercury, with the remainder
comprising gangue. This concentrate is treated in a
proc~ essentially comprising the process flow diagram
presented in the figure, and due to the presence of a
significant amount of gold, mercury, and antimony, the
While these products are representative of the types
known to be formed, the only product of primary importance
is antimony sulfide. The arsenic values remain 4S
in solution, permitting the antimony sulfides to be recovered
by filtering or other conventional separation
techniques.
The concentration of the starting materials is not
particularly important to effect the desired separation, SO
although the process may be conducted more efficiently
if the thioantit;nonate concentration in the starting solution
is from about 20 to about 80 grams per liter, and
preferably from about 40 to about 60 grams per liter.
Also the concentration of thioarsenate is not important ss
as the purity of the fmal antimony sulfide product may
be controlled by recycling this product stream back to
the oxidation step until the desired purity is attained. In
order to obtain a fmal antimony sulfide product possessing
less than about 0.4 percent arsenic and recovering 60
95 percent of the antimony in solution, the ratio of the
thioantimonate concentration to thioarsenate concentration
should be maintained at least at about two to
one.
The amount of oxygen consumed during the reaction 6S
is critical to the antimony-arsenic separation. If insufficient
oxygen is provided, the antimony recovery will be
adversely affected. If too much oxygen is provided, all
4,051,220
8
tained at about ll5° C and well agitated in order to
oxidize 4.40 pounds per minute ofantimony as antimony
.sulfide. This antimony sulfide precipitates from solution
with only a very minor amount of arsenic and is then
separated from solution;·This antimony sulfide is recovered,
and may be further processed as desired. The
remainder of the solution is treated with sulfuric acid in
order to precipitate the remaining antimony and all of
the arsenic in their sulfide forms, which are then discarded.
This acidified solution is then evaporated to
remove the water, and the remaining sodium salts are
roasted at about 650° C for approximately 1 hour to
produce sodium sulfate. This sodium sulfate is then
reduced with coke to produce an off-gas stream of carbon
dioxide and carbon monoxide and to convert the
sodium sulfate to sodium sulfide. The sodium sulfide
may then be recirculated to the sodium sulfide leaching
stage.
7
process flow diagram illustrates preferred techniques
for recovering these values.
The process is operated in a I;;ontinuous fashion with
70.7 pounds of feed introduced into the process per
minute. The concentrate is initially .roasted at a temper- S
ature of about 500· C in a neutral. atmosphere for. a
residence time of approximately 1.5 hours with elemental
sulfur being added at a rate of 50 pounds per ton of
concentrate being treated. The initial feed concentrate
contains approximately 2.04 pounds/minute arsenic, 10
4.56 pounds/minute antimony, and 0.021 ounces/minute
of gold. During the roast, the arsenopyrite is converted
to iron sulfide and arsenic sulfide, and about 90%
of the mercury is removed in the roast off-gas stream.
The products from the roast are then introduced into 15
the leach phase of the process and contacted with a
recycled solution containing approximately 10 grams
per liter antimony, 25 grams per liter arsenic, 276 grams
per liter sodium sulfide, 5 parts per million gold, and
about 0.1 grams per liter mercury. The leach reaction is 20 EXAMPLE 2
conducted at about 1()2° C, resulting in a product analysis
which indicates that essentially all of the copper and A feed material comprising essentially about 35%
silver sulfides are left in the residue, along with most of chalcopyrite, 35% tetrahedrite, 10% pyrite, 5% sphalthe
gold and minor amounts of arsenic, antimony, and erite, 4% galena, 3% pyrrhotite and minor amounts of
mercury. This residue is separated from the solution, 25 other metal sulfide values was leached with a sodium
washed, and is available for further processing for the sulfide solution having a sodium sulfide concentration
recovery of the various metal values contained therein ofabout 265 grams per liter, resulting in a solution polas
desired. seasing 159 grams of antimony in the form of sodium
The products in solution as a result of the sodium thioantimonite. The solution was subjected to evaporasulfide
leach reaction include sodium thioantimonite 30 tion and then cooled to about 20° C, and asitated at this
and sodium thioarsenite, along with some mercury and temperature for 1 hour. The product analysis indicated
gold. This solution is contacted with elemental sulfur at 126 grams of antimony remained in the mother liquor,
a temperature of about SOo C in order to produce so- while 33 grams or 20.7 percent of the antimony was
dium thioantimonate and sodium thioarsenate. The tem- crystallized.
perature of the solution is reduced to about 18° C, re- 35 A 300 mi. sample of this remaining mother liquor,
sulting in the crystallization of about 4.23 pounds per having an antimony concentration of71 grams per liter,
minute antimony and 1.52 pounds per minute arsenic, with the total amount of antimony being 21.2 grams,
and trace amounts of gold and mercury. The~. was then contacted with elemental sulfur and agitated
solution is then recycled to the sodium sulfide leach for 1 hour at a temperature of 95° C, and the resulting
stage, and the crystals are ree;Jissolved using approxi- <40 product solution was then cooled to about 20° C and
mately.5% of the recycle solutl~n as a bleed str~ and asitated for 1 hour. The resulting product analysis indithe
antlmony sulfide wash solution produced later m the cated that 18.5 grams of antimony were present in the
process. . . . crystals, while only 2.7 grams of antimony remained in
Upon redlsso1vmgthe crystals, the pH ofthe solution the mother liquor providing an antim<>ny crystallizais
greater t~ 13, and sufficient 93% sulfuric acid. ~ 45 tion of 87%. '
added to adjust the pH to ~bout 12: Hydrolen sulfide 18 The comparative tests of Example 2 therefore clearly
r~overed as a result of ~~s pH adJus~~ent,as w~ll as a indicate the substantial increase in antimony crystalliza-
1IllJ!0r amount of preclplta~ ~ntaining arsenlC ~d tion recovery as a result of convertin. the sodium thiantlmony
sulfides..The Solu~lon 18 then contacted ~th oantimonite to sodium thioantimonate rior to the crys-
48.4 pounds per day of Aliquat 336, a General Mills SO tallizati· P
product comprising tricaprylyl monomethyl ammo- Wbatn
.. I' ed·'
nium chloride of the formula hereinabove presented, 18 c &lID IS.. .
loaded on activated carbon. The Aliquat 3361.ctivated 1. A.process for treating ~~tal sulfides 1Jt the presence
carbon agent is arranged in a column, and the solution is of antimo~y sulfide comprlSm': ... .
percolated through the column. Substantially all of the 55 .. leaching the metal sulfi~es WIth ~1~ ~ulfide m
gold and some mercury are adsorbed onto this Aliquat·order to produce ~ resIdue ~ntainin~ mso~uble
336 surface. The temperature of this ion exchange reac-· s~fid~ and a solutlo~ ~mpr1SJD' sodium thioantion
is maintained at about 25° C. tlmomte and the remammg metal sulfide values;
The solution is then treated for mercury removal by b.~ting the insoluble metal sulfides from the
adjusting the pH to about 8, again using 93% sulfuric 60 solution;
acid at a temperature of about 25° C. This recovers c. oxidizing .the sodium thioantimonite in solution to
essentially all of the mercury and silica, while precipi- sodium thioantimonate;
tating very minor amounts of antimony and arsenic. d. crystallizing a portion of the sodium thioantimon-
The solution, now essentially comprisin. sodium thi- ate from the solution; and
oantimonate and sodium thioarsenate, is treated with 65 e. separatin. the crystallized sodium thioantimonate
sufficient sodium hydroxide to adjust the pH to.about 12 from the solution.
and introduced into an autoclave.About.3.3 pounds per 1. The process of claim 1 wherein the metal sulfides
minute of oxygen is injected· and the system is main- being treated include chalcopyrite. ,
4,051,220
S
10
activated carbon surface, the ion exchange agent
comprising:
wherein R is a mixture of Cg and ClOcarbon chains,
in order to remove substantially all of the gold from
solution.
11. A process for treating metal sulfides including
arsenic sulfides in the presence ofantimony sulfide comprising:
a. leaching the metal sulfides with sodium sulfide in
order to produce a residue containing insoluble
sulfides and a solution comprising sodium thioantimonite
and the remaining metal sulfide values;
b. separating the insoluble metal sulfides from the
solution;
c. oxidizing the sodium thioantimonite in solution to
sodium thioantimonate;
d. crystallizing a portion of the sodium thioantimonate
from the solution;
e. separating the crystallized sodium thioantimonate
from the solution;
f. redissolving the crystallized sodium thioantimonate
to form a solution comprising sodium thioantimonate
and sodium thioarsenate;
g. subjecting the sodium thioantimonate/sodium thioarsenate
solution to partial oJtidation by injecting
sufficient oxygen so as to maintain a fmal solution
e.m.f. of from about 300 millivolts to about 500
millivolts, measured with platinum/saturated Calomel
electrodes while maintaining the product solu'
tion at a pH of from about 7 to about 11 in order to
oxidize and precipitate a substantial portion of the
sodium thioantimonate as antimony sulfide while
leaving substantially all of the sodium thioarsenate
in solution.
12. A process for treating metal sulfides in the presence
of antimony sulfide comprising:
a. leaching the metal sulfides with sodium sulfide in
order to produce a residue containing insoluble
sulfides and a solution comprising sodium thioantimonite
and the remaining metal sulfide values;
b. separating the insoluble. metal sulfides from the
solution;
c. oxidizing the sodium thioantimonite with elemental
sulfur in solution to produce sodium thioantimonate;
d. crystallizing a portion of the sodium thioantimonate
from the solution; and
e. separating the crystalliZed sodium thioantimonate
from the solution.
13. The process of claim 12 wherein the reaction is
conducted within a temperature range of from about
20· C to about 200· C.
14. The process of claim 12 wherein the reaction is
conducted within a temperature range of from about
50· C to about 100· C.
15. The process of claim 12 wherein the reaction is
conducted for a period oftime ofbetween about 0.1 and
about 10 hours.
16. The process of claim 12 wherein the reaction is
conducted for a period of time of between about 0.25
and about 0.5 hours.• • • • •
20
2S
9
3. The process of claim 1 wherein the antimony sulfide
comprises one or more members selected from the
group consisting of tetrahedrite and stibnite.
4. The process of claim 1 wherein the metal sulfides
being treated include arsenopyrite.
5. The process of claim 4 wherein the metal sulfides
being treated are initially roasted within a temperature
of from about 400· C to about 600· C.
6. The process of claim 1 wherein the metal sulfides
being treated include gold. 10
7. The process of claim 6 comprising:
a. redissolving the crystallized sodium thioantimonate;
b. adjusting the pH of the solution resulting from the 15
redissolving of the crystals to about 12;
c. contacting the redissolved sodium thioantimonate
solution with an ion exchange agent loaded onto an
activated carbon surface, the ion exchange agent
comprising:
wherein R is a mixture of Cgand CIO carbon chains,
in order to remove substantially all of the gold from
solution. 30
8. The process of claim 1 wherein the metal sulfides
being treated include arsenic sulfides.
9. The process of claim 8 comprising:
a. redissolving the crystallized sodium thioantimonate
to forma solution comprising sodium thioantimon- 35
ate and sodium thioarsenate;
b. subjecting the sodium thioantimonate/sodium thioarsenate
solution to partial oxidation by injecting
sufficient oxygen so as to maintain a final solution 40
e.m.f. of from about 300 millivolts to about 500
millivolts, measured with Platinum/saturated Calomel
electrodes while maintaining the product solution
at a pH of from about 7 to about 11 in order to
oxidize and precipitate a substantial portion of the 4S
sodium thioantimonate as antimony sulfide while
leaving substantially all of the sodium thioarsenate
in solution.
10. A process for treating metal sulfides including
gold in the presence of antimony sulfide comprising: 50
a. leaching the metal sulfides with sodium sulfide in
order to produce a residue containing insoluble
sulfides and a solution comprising sodium thioantimonite
and the remaining metal sulfide values;
b. separating the insoluble metal sulfides from the 55
solution;
c. oxidizing the sodium thioantimonite in solution to
sodium thioantimonate;
d. crystallizing a portion of the sodium thioantimonate
from the solution; 60
e. separating the crystallized sodium thioantimonate
from the solution;
f. redissolving the crystallized sodium thioantimonate;
g. adjusting the pH of the solution resulting from the 6S
redissolving of the crystals to about 12;
h. contacting the redissolved sodium thioantimonate
solution with an ion exchange agent loaded onto an
UNITED STATES PATENT OFFICE
CERTIFICATE OF CORRECTION
Patent No.--4-,0-51-,2-2-0 ------
Enzo L. Co1trinari
Dated September 27, 1977
Inventor(s)----------------------------
It is certified that error appears in the above-identified patent
and that said Letters Patent are hereby corrected as shown below:
On the second page in Column 1 under Summary of the
Invention at line 61 reading "comprising essentially
the steps of leaching and concentrates", should read-"
comprising essentially the steps of leaching the
concentrates"--
Signed and Scaled this
Seventeenth Day 0 f January 1978
[SEAL)
Attest:
RUTH C MASON LLJTRELLE F. PARKER
Attesting Officer Acting Commissioner of Patents and Trademarks