United States Patent [19]
Sherman et al.
[11]
[45]
Patent Number:
Date of Patent:
4,557,905
* Dec. 10, 1985
FOREIGN PATENT DOCUMENTS
2085856 5/1982 United Kingdom .
OTHER PUBLICATIONS
Heinen et al. "Enhancing Percolation Rates in Heap
[21] Appl. No.: 649,921
[22] Filed: Sep. 13, 1984
[54] LEACHING AND WASHING A
FLOCCULATED SLURRY HAVING A FIBER
CONTENT
[57] ABSTRACT
Particlized mineral material, such as gold ore, silver ore,
or coal, is subjected to a leaching process in a manner to
maximize treatment effectiveness even when the partic1ized
mineral material contains small fines. The material
is slurried with a flocculating material and fibers,
such as cellulosic fibers, fiberglass fibers, or ceramic
fibers, and a liquid, and then is passed to the top of a
leaching reactor. The slurry is continuously passed
downwardly in the reactor while the leaching liquid,
such as a cyanide solution, is passed counter-current to
the slurry. Leaching liquid is removed from the top of
the leaching reactor by a stilling well, and then passed
through a carbon adsorber and reintroduced into the
reactor. Leached slurry is passed to a continuous washing
station, with spent wash liquid from the top of the
washing station being utilized as a slurrying liquid for
the particlized mineral material.
Leaching of Gold-Silver Ores" International Bureau of
Mines., 1979.
Perry, "Refining Zinc Silicate Ore by Special Leaching
Technique" Chemical Engineering, 10/10/66 pp.
182-184.
Mager "Technical and Commercial Aspects of the Refining
of Leaching Residues from Zinc Electrolysis",
Erznetall, May 1976, pp. 224-229 [Eng. Abs.].
Shoemaker et al. "Recovery of Gold and Silver from
Ores" paper to International Precious Metals Institute,
10/23/80.
Sederov "Intensification of Zinc Pulp Settling and Solution
Clarifying Through the Use of F10cculants",
Yearbook of the Institute of Non-Ferrous Metallurgy,
1978, pp. 22-37. [Eng. Abs.].
Habashi, "Pressure Hydrometallurgy: Key to Better
and Nonpolluting Processes "; E/MJ, pp. 96-100 (2/71)
and 88-94 (5171).
Primary Examiner-John Doll
Assistant Examiner-Bob Stoll
Attorney, Agent, or Firm-Cushman, Darby & Cushman
21 Claims, 3 Drawing Figures
Michael I. Sherman; Carl L. Elmore,
both of Glens Falls, N.Y.; Robert J.
Brison, Golden, Colo.
Kamyr, Inc., Glens Falls, N.Y.
The portion of the term of this patent
subsequent to Feb. 26, 2002 has been
disclaimed.
Inventors:
Assignee:
Notice:
[75]
[73]
[ * ]
Related U.S. Application Data
[62] Division of Ser. No. 503,178, Jun. 10, 1983, Pat. No.
4,501,721.
[51] Int. Cl.4 COIG 7/00
[52] U.S. Cl 423/27; 423/29;
423/109; 423/150; 423/578 A; 75/2; 75/3;
75/101 R; 75/105; 75/117; 75/119; 75/118 R;
75/120; 75/121
[58] Field of Search 423/25, 27, 29, 109,
423/150,578 A; 75/0.5 A, 2,3, 101 R, 117, 118
R, 105, 119, 120, 121
[56] References Cited
U.S. PATENT DOCUMENTS
2,479,930 8/1948 Herkenhoff et al. 423/29
3,151,972 10/1964 Streib 75/1
3,788,841 1/1974 Agarwal et al. 75/103
4,071,611 1/1978 Chilson et al. 423/41
4,174,997 11/1979 Richter 162/19
4,256,705 3/1981 Heinen et al. 423/27
4,256,706 3/1981 Heinen et al. 423/29
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4,557,905
1
LEACHING AND WASHING A FLOCCULATED
SLURRY HAVING A FIBER CONTENT
This is a division ofapplication Ser. No. 503,178, filed 5
June to, 1983, now U.S. Pat. No. 4,501,721.
BACKGROUND AND SUMMARY OF THE
INVENTION
The leaching of constituents from particlized mineral 10
materials is practiced utilizing a wide variety of materials
and equipment. Leaching procedures are particularly
useful for the recovery of metals from particulized
mineral ores, such as gold and silver ores. The dominant
process for the extraction of such metals from ores is 15
leaching with alkaline cyanide solution and oxygen, and
this basic procedure has changed relatively little since
the issuance of the first patent thereon in 1887. Despite
extensive use of cyanide leaching, however, it has a
number of drawbacks associated therewith, including 20
the practical necessity of either grinding the ore fine for
continuous agitation leaching or utilizing batch leading
methods on coarser material, significant pollution loads,
and minimal adaptability.
According to the present invention a method for the 25
leaching of particlized mineral materials to remove
constituents therefrom is provided which has enhanced
effectiveness compared to prior art procedures. The
method according to the invention is particularly applicable
to the removal of metals from metal bearing ores, 30
such as gold and silver ores, but also is adaptable to
other processes, such as the removal of the pyritic,
organic, and sulfate sulfur compounds present in a solid
carbonaceous fuel of the coal or coke type.
The method according to the invention effects the 35
treatment of a slurry of particlized mineral material in a
continuous manner, with no large pressure losses and
with good metal removal efficiency. The process is
capable of treating particlized mineral materials in a
continuous manner even where there is a relatively 40
large percentage of small fines (e.g. 200 mesh or below),
without channelling and with excellent uniformity of
flow. The process according to the invention is easily
adaptable to high temperature and/or high pressure
conditions, and may be closed to the atmosphere 45
thereby reducing the pollution potential associated
therewith. The process also generally requires less
grinding equipment and energy and less pumping, agitating,
and like energy expenditures compared to prior
art continuous leaching processes, can handle ores of a 50
wide variety of sizes, and can handle soft materials-
such coke or coal.
Further, by practicing the invention substantially the
same results can be achieved as by leaching with carbon
added to the "pulp" being leached, without the neces- 55
sity of adding carbon. This is in part because the retention
time for the dissolved metal (e.g. gold) in contact
with ore is very short due to countercurrent flow in the
reactor vessel of the invention.
The invention also comprises a novel slurry of parti- 60
clized mineral material, and a method of removing metals
from a pregnant leaching solution utilizing a conventional
carbon adsorber device.
According to one aspect of the present invention, a
particlized mineral material, such as gold or silver ore, 65
is slurried with a liquid. The material is passed downwardly
in a generally vertically upstanding leaching
reactor vessel, and leaching liquid is passed counter-
2
currently (Le. upwardly) to the continuously downwardly
passing slurry. Treated slurry is continuously
removed from a bottom portion of the vessel, while
pregnant leaching liquid (with leached constituents, e.g.
gold or silver) is continuously removed from the top of
the vessel, as by utilizing a stilling well. The leached
slurry is continuously washed, preferably in a single
stage or in a two stage wash procedure utilizing a vessel
or vessels comparable to the leaching reactor. For two
stage washing, the spent wash liquid from the first stage
of the washing is utilized as the liquid for slurrying the
particulized mineral material.
In order to lock the ore particles in a stable network
for treatment in the continuous process according to the
invention, a flocculating agent and fibers are added to
the liquid and particulized mineral material during slurrying
thereof. Any suitable conventional flocculant,
such as synthetic polymers, may be utilized, and the
fibers may be selected from cellulosic fibers (e.g. wood
pulp fibers), fiberglass fibers, or ceramic fibers.
The utilization of flocculants and fibers is not restricted
to the practice of a continuous process. Rather
the formation of a slurry utilizing those materials is also
applicable to batch leaching and washing operations,
and the like.
The cyanide solution leaching liquid, containing metals
removed from particlized ores, is treated in a particular
manner to facilitate removal of the metal therefrom.
The pregnant leaching solution-that removed
from the top of the leaching reactor vessel described
above-is passed through a carbon adsorbing device.
Fresh carbon is added periodically to the top of the
device and loaded carbon removed from the bottom,
and effiuent from the carbon adsorption device is recycled
to the washing or leaching stage.
It is the primary object of the present invention to
provide for the effective removal of predetermined
constituents from a particlized mineral material. This
and other objects of the invention will become clear
from an inspection of the detailed description of the
invention, and from the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flow sheet illustrating the practice of a
method according to the present invention for the treatment
of gold or silver ore;
FIG. 2 is a schematic illustration of exemplary apparatus
utilizable for the practice of a method according
to the present invention; and
FIG. 3 is a detail cross-sectional schematic view of an
alternative form that a leaching reactor vessel could
take for the practice of a method according to the present
invention.
DETAILED DESCRIPTION OF THE
DRAWINGS
A flow sheet illustrating practice of an exemplary
method according to the present invention is provided
as FIG. 1 of the drawings. While the invention will be
primarily described with respect to the removal of gold
or silver from gold and silver ores, it is to be understood
that the invention has broader applicability, and is applicable
to a wide variety of particlized mineral materials
to be treated with a leaching liquid. For instance, the
invention is utilizable with a wide variety of metal bearing
ores (such as copper and zinc ores), as well as for the
removal of pyritic, organic and sulfate sulfur compounds
from coal or the like.
4,557,905
3
According to the invention as illustrated in FIG. 1,
the ore is first crushed or ground and then slurried, with
flocculants and fibers added to the slurry to lock ore
particles in a stable network. The slurry is passed to a
leach tank for counter-current flow treatment with a 5
leaching liquid. The pregnant solution is passed to a
station for metal recovery, while the leached slurry is
passed to wash tanks, with the residue passed to a tailings
pond, or like disposal area.
FIG. 2 schematically illustrates equipment that may 10
be utilizable for the practice of the novel aspects of the
process illustrated by the flow sheet of FIG. 1. The
particlized ore is passed by conveyor 10 or the like to
the slurrying tank 11, which may include a conventional
mixing means 12. A slurrying liquid is added to the tank 15
11 from line 13, the liquid in line 13 preferably comprising
water and/or the spent wash liquid from one or
more washing stages to be hereinafter described.
Also added to the slurry tank 11 is a flocculant from
source 14, and fibers from source 15. The flocculant and 20
fibers may be any suitable flocculant or fibers that are
capable of locking ore particles, including fines, in the
slurry in a stable network so that they may be subsequently
subjected to the leaching treatment. Typical
flocculants comprise synthetic polymers of anionic, 25
cationic or nonionic types, and typical fibers comprise
cellulosic fibers, fiberglass fibers, ceramic fibers, and
combinations thereof.
The slurry from tank 11 is passed through line 17 to
the top of a substantially vertically elongated leaching 30
reactor vessel 18. The vessel may be of a type as disclosed
in U.S. Pat. Nos. 4,061,193 or 4,174,997, having
a "stilling well" structure 19 at the top thereof above
the slurry introducing point 20 of a slurry introduction
tube 21, and having a rotating liquid introducing device 35
22 at the bottom thereof, preferably commonly rotatable
with slurry discharge structure 23.
The slurry flows continuously downwardly in vessel
18, and is ultimately discharged through line 24 at a
bottom portion of the vessel 18. Leaching liquid is intro- 40
duced through line 25-as from source 26-so that it
flows to the distributor 22, and then flows upwardly in
vessel 18-counter-currently to the slurry flow therein.
The fibers and flocculant in the ore slurry lock the ore
particles in a stable network so that leaching can occur 45
without channelling, and with a minimal pressure drop
over the vessel 18. Thus fines of 200 mesh, or smaller,
can be handled without substantial difficulty. Additionally,
ores having particle sizes up to ~ inch mesh, or
even larger, may be handled at the same time that the 50
fines are being handled.
The leached slurry withdrawn in line 24 passes to a
washing station. At the washing station, preferably a
single washer 27 is provided, although a first washer
(27) and a second washer 28 (or more) may be provided. 55
The vessels 27, 28 are substantially identical to the vessel
18, but generally of smaller size, and include a stilling
well arrangement 29, 29' at the top thereof, and a
rotating liquid introducing structure 30, 30' at the bottom
thereof. Where two vessels are utilized, clean wash 60
water enters vessel 28 through line 31, passes through
liquid distributor 30' counter-current to the slurry flow
in vessel 28, and spent wash liquid is withdrawn from
the stilling well 29' through line 32, to be used as feed
wash liquid for the first wash vessel 27. Spent wash 65
liquid in vessel 27 withdrawn from stilling well 29
through conduit 33 preferably is passed to the slurrying
tank 11, providing a liquid feed to line 13. The washed
4
slurry is withdrawn from second wash tank 28 through
line 34, and is passed to a tailings pond, or like disposal
site.
Where only a single wash vessel 27 is utilized, line 31
is connected to structure 30, and line 32 to the tailings
pond or the like.
An alternative form the leaching reactor 18 of FIG. 2
may take is illustrated in FIG. 3, with functionally related
components in the two embodiments illustrated by
the same reference numeral, only the reference numeral
being preceded by a "I" in FIG. 3. The form of vessel
118 may, of course, be utilized for the wash vessels 27,
28, also.
For the vessel 118, the slurry feed and the treatment
liquid feed are preferably provided in concentric tubes
125, 117. The tube 117 is connected to rotating slurry·
introducing device 121, which introduces slurry at level
120 below the overflow launder or stilling well 119
provided at the top of the vessel 118.
The liquid introduction pipe 125 is operatively connected
to the liquid distributing device 122 at the bottom
of the vessel 118, with paddles or like slurry discharge
mechanism 123 provided on the bottom of the
vessel 122. Note that in this embodiment the structures
121,122 are rotated by acommon shaft 37 connected up
to a conventional drive motor 38. A discharge control
valve 39 may be provided in the line 24 so that the
vessel 118 may be utilized for batch operations, as well
as for continuous operations, and to control the rate of
solids removal.
Returning to FIG. 2, a method for facilitating removal
of the metals from the pregnant leaching solution
withdrawn from the stilling well 19 will now be described.
Pregnant leaching solution is withdrawn from stilling
well 19 through line 42, and passes to the carbon adsorbing
device 43, ultimately passing to line 25.
Operatively connected to the device 43 via line 44 is
the storage tank 45, which is adapted to store strong
leaching solution therein. The invention is particularly
applicable to the leaching of gold and silver ores, in
which case the leaching liquid from source 26 comprises
a caustic cyanide solution, such as sodium cyanide,
and the solution in tank 45 is· supplied from a
source 46 of hot caustic cyanide solution. Fresh carbon
is periodically added to the top of device 43 via line 47
and loaded carbon is withdrawn from the bottom
through line 44 and dumped into tank 45.
From tank 45, caustic and carbon are periodically
passed by pump 49 through valve 50 to metal removal
station 51. From metal removal station 51 carbon is
passed to carbon reactivation station 52 to supply fresh
carbon, through line 47, to device 43 as needed.
Operation
An exemplary method of operation of the apparatus
of FIG. 2, in the practice of an exemplary method according
to the present invention, will now be described.
Particlized gold ore is fed by conveyor 10 to tank 11,
to which liquid from line 13, polyall flocculant from line
14, and cellulosic fibers from line 15 are added. Sufficient
fibers are added so that they comprise between
about 0.01 percent and 10 percent, by weight, of the
total slurry, preferably about 0.05-0.75%.
The slurry is continuously mixed in tank 11, and then
is continuously pumped through line 17 to enter tube 21
of the vessel 18, and continuously passed downwardly
therein. Sodium cyanide leaching liquid is introduced
55
10
4,557,905
6
synthetic polymers of anionic, cationic, and non-ionic
types.
6. A· method of removing metal from particlized
metal bearing ore, utilizing a treatment vessel, compris5
ing the steps:
(a) mixing the ore with a liquid to form a liquid slurry,
and with a floccuating material so as to hold the
ore in a stable network;
(b) continuously passing the slurry downwardly in
the vessel;
(c) continuously passing a leaching liquid, capable of
leaching the metal from the ore, upwardly in the
vessel, counter-current to the slurry passage, to
remove metal from the ore of the slurry;
(d) continuously removing the treated slurry from a
bottom portion of the vessel; and
(d) continuously removing pregnant leaching liquid,
with removed metal therein, from a top portion of
the vessel.
7. A method as recited in claim 6 comprising the
further step (t) of continuously washing the slurry removed
in step (d).
8. A method as recited in claim 7 wherein step (t) is
practiced utilizing a washing vessel, and by passing
wash liquid upwardly in the vessel counter-current to
slurry moving downwardly in the vessel, with spent
wash liquid removed from a top portion of the vessel
and washed slurry removed from a bottom portion of
the vessel.
9. A method as recited in claim 6 wherein step (a) is
further practiced by adding fibers to the particlized ore
and slurrying liquid so as to facilitate locking the particlized
ore in this stable network.
10. A method as recited in claim 9 wherein the flocculent
is selected from the group consisting essentially of
synthetic polymers of anionic, cationic, and non-ionic
types; and wherein the fibers are selected from the
group consisting essentially of cellulosic fibers, fiberglass
fibers, ceramic fibers, and mixtures thereof; and
wherein the fibers comprise about 0.01%-10%, by
weight, of the slurry.
11. A method as recited in claim 6 wherein the leaching
liquid in step (c) is a cyanide solution.
12. A method as recited in claim 11 comprising the
further step of: (g) continuously passing pregnant liquid
withdrawn in step (e) through a carbon adsorbing device,
and reintroducing the liquid into the vessel as
leaching liquid for step (c).
13. A method as recited in claim 6 wherein step (a) is
further practiced by adding fibers to the particlized
mineral material and slurrying liquid so as to facilitate
locking the particlized mineral material in a stable network.
14. A method as recited in claim 6 wherein the flocculent
is selected from the group consisting essentially of
synthetic polymers of anionic, cationic, and non-ionic
types.
15. A method of removing metal from particlized
60 metal bearing ore, utilizing a treatment vessel, comprising
the steps:
(a) mixing the ore with a liquid to form a liquid slurry,
and with fibers so as to facilitate locking of the ore
in a stable network;
(b) continuously passing the slurry downwardly in
the vessel;
(c) continuously passing a leaching liquid, capable of
leaching the metal from the ore upwardly in the
5
through line 25 and distributing device 22 to continuously
flow counter-current to the slurry in vessel 18,
and pregnant leaching liquid is removed from the stilling
well 19-without the necessity for utilizing screens-
in line 42.
The pregnant solution in line 42 passes through the
carbon adsorber device 43, and then is recirculated
through line 25 to the device 22. Fresh carbon is supplied
to, and loaded carbon removed from, device 43 as
necessary.
Leached slurry is discharged by device 23 from the
bottom of the vessel 18 into line 24, and passes to the top
of washing stage 27. The slurry flows downwardly
through washing stage 27, and then may be fed to the
top of vessel 28, and ultimately passes through dis- 15
charge 34 to a disposal site. Wash water introduced in
line 31 to vessel 28 flows counter-currently to the
slurry, and the spent wash liquid withdrawn from line
33 is pumped to the slurry in tank 11.
Utilizmg the equipment illustrated in FIGS. 2 and 3, 20
it is easy to adapt the process to high temperature and
high pressures, thus providing versatility in the processes
which may be practiced, and in the available
leaching liquids. Also, the process can be closed to the 25
atmosphere thereby minimizing discharges of pollutants
into the atmosphere. Because little agitation of the
slurry is necessary (only that small amount provided in
tank 11), energy requirements are minimized, and the
process is readily adaptable to the handling of "soft" 30
particlized mineral materials, such as coal. Further, the
process can be operated in a continuous manner even
when a relatively high percentage of fines, including
small fmes, are present, and may be practiced with particles
up to about! inch in diameter. 35
While the invention has been herein shown and described
in what is presently conceived to be the most
practical and preferred embodiment thereof, it will be
apparent to those of ordinary skill in the art that many
modifications may be made thereof within the scope of 40
the invention, which scope is to be accorded the broadest
interpretation of the appended claims so as to encompass
all equivalent methods and products.
What is claimed is:
1. A method of treating particlized metal bearing ore 45
to effect removal of the metal therefrom, comprising
the steps of:
(a) forming a slurry from the particlized ore, liquid, a
flocculating agent, and fibers, the flocculating
agent and fibers causing the particlized mineral 50
material to be locked in a stable network;
(b) subjecting the slurry to treatment with a leaching
liquid; and
(c) removing the metal from the leaching liquid after
treatment of the slurry.
2. A method as recited in claim 1 wherein the fibers
are selected from the group consisting essentially of
cellulosic fibers, fiberglass fibers, ceramic fibers, and
mixtures thereof, the fibers comprising about 0.01 percent
to 10 percent, by weight, of the slurry.
3. A method as recited in claim 2 wherein the flocculant
is selected from the group consisting essentially of
synthetic polymers of anionic, cationic, and non-ionic
types.
4. A method as recited in claim 1 wherein the leach- 65
ing liquid in step (b) is a cyanide solution.
5. A method as recited in claim 1 wherein the flocculant
is selected from the gra.up consisting essentially of
8
(e) continuously removing pregnant leaching liquid,
with removed sulfur compounds therein, from a
top portion of the vessel.
18. A method as recited in claim 17 comprising the
5 further step (f) of continuously washing the slurry removed
in step (d).
'19. A method as recited in claim 17 wherein the flocculent
is selected from the group consisting essentially
of synthetic polymers of anionic, cationic, and non-ionic
types; and wherein the fibers are selected from the
group consisting essentially of cellulosic fibers, fiberglass
fibers, ceramic fibers, and mixtures thereof; and
wherein the fibers comprise about 0.01 %-10%, by
weight, of the slurry.
20. A method of treating particlized coal or coke to
. effect removal of sulfur compounds therefrom, comprising
the steps of:
(a) forming a slurry from the particlized coal or coke,
liquid, a flocculating agent, and fibers, the flocculating
agent and fibers causing the particlized coal
or coke to be locked in a stable network;
(b) subjecting the slurry to treatment with a leaching
liquid; and
(c) removing the sulfur compounds from the leaching
liquid after treatment of the slurry.
21. A method as recited in claim 20 wherein the fibers
are selected from. the group consisting essentially of
cellulosic fibers, fiberglass fibers, ceramic fibers, and
mixtures thereof, the fibers comprising about 0.01 percent
to 10 percent, by weight, of the slurry.
* * * * *
20
4,557,905
7
vessel, counter-current to the slurry passage, to
remove metal from the ore of the slurry;
(d) continuously removing the treated slurry from a
bottom portion of the vessel; and
(e) continuously removing pregnant leaching liquid,
with removed metal therein, from a top portion of
the vessel.
16. A method as recited in claim 15 comprising the 10
further step (f) of continuously washing the slurry removed
in step (d).
17. A method of removing sulfur compounds from
particlized coke or coal, utilizing a treatment vessel,
15 comprising the steps:
(a) mixing the coke or coal with a liquid to form a
liquid slurry, and with fibers and a flocculating
material so as to hold the coke or coal in a stable
network;
(b) continuously passing the slurry downwardly in
the vessel;
(c) continuously passing a leaching liquid, capable of
leaching sulfur compounds from the particlized 25
coke or coal upwardly in the vessel, counter-current
to the slurry passage, to remove sulfur from
the particlized coke or coal of the slurry;
(d) continuously removing the treated slurry from a 30
bottom portion of the vessel; and
35
40
45
50
55
60
65