U.S. patent application number 13/674409 was filed with the patent office on 2013-03-14 for production of metal products directly from underground ore deposits.
This patent application is currently assigned to COOPERATIVE MINERAL RESOURCES, LLC. The applicant listed for this patent is Cooperative Mineral Resources, LLC. Invention is credited to Steven G. Axen, Steven C. Carlton, Kevin P. Kronbeck.
Application Number | 20130061719 13/674409 |
Document ID | / |
Family ID | 42678429 |
Filed Date | 2013-03-14 |
United States Patent
Application |
20130061719 |
Kind Code |
A1 |
Carlton; Steven C. ; et
al. |
March 14, 2013 |
PRODUCTION OF METAL PRODUCTS DIRECTLY FROM UNDERGROUND ORE
DEPOSITS
Abstract
A process for producing metal compounds directly from
underground mineral deposits including steps of forming a borehole
at a site into a mineral deposit containing metal compounds,
inserting a slurry-forming device having a nozzle into the borehole
adapted to direct pressurized water through the nozzle into the
mineral deposit, supplying pressured water through the nozzle into
the mineral deposit forming a mineral slurry containing metal
compounds, extracting the mineral slurry containing metal compounds
through the borehole, leaching the mineral slurry converting the
metal compounds to a soluble form in a leach solution, and removing
metals and metal compounds by treating the leach solution with an
extraction treatment removing the metal products. Steps of leaching
the mineral slurry and removing metal products are performed at a
location remote from the borehole site. In one alternative, the
step of removing metal products from mineral slurry is accomplished
by pyrometallurgical processes.
Inventors: |
Carlton; Steven C.; (Emily,
MN) ; Axen; Steven G.; (Golden, CO) ;
Kronbeck; Kevin P.; (Baxter, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cooperative Mineral Resources, LLC; |
Brainerd |
MN |
US |
|
|
Assignee: |
COOPERATIVE MINERAL RESOURCES,
LLC
Brainerd
MN
|
Family ID: |
42678429 |
Appl. No.: |
13/674409 |
Filed: |
November 12, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12695045 |
Jan 27, 2010 |
|
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13674409 |
|
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|
61147502 |
Jan 27, 2009 |
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Current U.S.
Class: |
75/414 ; 205/771;
423/49; 75/712 |
Current CPC
Class: |
C25C 1/10 20130101; C22B
3/08 20130101; C22B 5/00 20130101; Y02P 10/20 20151101; C22B 47/00
20130101; C22B 3/00 20130101; C22B 1/00 20130101; Y02P 10/234
20151101; C22B 3/04 20130101; E21B 43/29 20130101 |
Class at
Publication: |
75/414 ; 423/49;
75/712; 205/771 |
International
Class: |
C22B 3/08 20060101
C22B003/08; C22B 5/00 20060101 C22B005/00; C25C 1/10 20060101
C25C001/10; C22B 47/00 20060101 C22B047/00 |
Claims
1. A process for producing metal compounds directly from
underground mineral deposits in an environmentally sensitive area
comprising the steps of: (a) forming a borehole from an accessible
site into an underground mineral deposit containing metal compounds
including oxides of manganese beneath the environmentally sensitive
area; (b) inserting a slurry-forming device having a nozzle into
the borehole adapted to direct pressurized water through the nozzle
into the mineral deposit under the environmentally sensitive area;
(c) supplying pressured water through the nozzle of the
slurry-forming device into the mineral deposit forming a mineral
slurry containing the metal compounds from the mineral deposit
under the environmentally sensitive area; (d) extracting and
dewatering the mineral slurry containing the metal compounds
through the borehole in the environmentally sensitive area; (e)
transporting the dewatered mineral slurry as extracted from the
mineral deposit away from the borehole to a location remote from
the environmentally sensitive area; (f) leaching the extracted
mineral slurry at the remote location to convert the metal compound
to a soluble form in a leach solution; and (g) removing metal
compounds by treating the leach solution with an extraction
treatment adapted to remove the metal compounds.
2. The process for producing metal compounds directly from
underground mineral deposits according to claim 1, where the
mineral slurry is transported by a device selected from a group
consisting of truck, rail, pipeline, and a combination of two or
more thereof.
3. The process for producing metal compounds directly from
underground mineral deposits according to claim 1 further
comprising the step of: prior to the step of leaching the mineral
slurry, grinding particulate in the mineral slurry to a particle
size of about 80% smaller than 100 mesh.
4. The process for producing metal compounds directly from
underground mineral deposits according to claim 1 further
comprising the step of: prior to the step of leaching the mineral
slurry, grinding particulate in the mineral slurry to a particle
size of about 80% smaller than 200 mesh.
5. The process for producing metal compounds directly from
underground mineral deposits according to claim 1, further
comprising the step of: after the step of leaching the mineral
slurry, treating the leach solution with one or more treatments to
remove selected metals and metal compounds.
6. The process for producing metal compounds directly from
underground mineral deposits according to claim 1 where the step of
leaching the mineral slurry comprises leaching the mineral slurry
to put desired metal compounds into solution.
7. The process for producing metal compounds directly from
underground mineral deposits according to claim 1 where the step of
leaching the mineral slurry comprises leaching the mineral slurry
with sulfurous acid.
8. The process for producing metal compounds directly from
underground mineral deposits according to claim 1 where the leach
solution comprises at least one reducing agent selected from a
group consisting of SO.sub.2, carbon, reducing sugar, molasses, and
a combination of two or more thereof.
9. The process for producing metal compounds directly from
underground mineral deposits according to claim 1 where the leach
solution has a pH of 3 or lower.
10. The process for producing metal compounds directly from
underground mineral deposits according to claim 1 further
comprising the step of: prior to the step of removing metal
compounds, chemically treating the leach solution with oxidizing
agents producing metal compounds.
11. The process for producing metal compounds directly from
underground mineral deposits according to claim 1 further
comprising the step of: prior to the step of removing metal
compounds, chemically treating the leach solution with reducing
agents producing selected metal products.
12. The process for producing metal compounds directly from
underground mineral deposits according to claim 1 where the step of
removing metal compounds comprises electrochemically treating the
leach solution removing selected metals or metal compounds.
13. The process for producing metal compounds directly from
underground mineral deposits according to claim 1 further
comprising forming a second slanted borehole in the environmentally
sensitive area intersecting the first borehole in the mineral
deposit containing metal compounds including oxides of manganese;
where the step of inserting a slurry-forming device is into the
second borehole, and where the step of extracting is through the
first borehole.
14. A process for producing metal compounds directly from
underground mineral deposits in an environmentally sensitive area
comprising the steps of: (a) forming a borehole from an accessible
site into an underground mineral deposit containing metal compounds
including oxides of manganese beneath the environmentally sensitive
area; (b) inserting a slurry-forming device having a nozzle into
the borehole adapted to direct pressurized water through the nozzle
into the mineral deposit under the environmentally sensitive area;
(c) supplying pressured water through the nozzle of the
slurry-forming device into the mineral deposit forming a mineral
slurry containing the metal compounds from the mineral deposit
under the environmentally sensitive area; (d) extracting and
dewatering the mineral slurry containing the metal compounds
through the borehole in the environmentally sensitive area; (e)
transporting the dewatered mineral slurry as extracted from the
mineral deposit away from the borehole to a location remote from
the environmentally sensitive area; (f) physically separating the
extracted mineral slurry at the remote location; and (g) removing
metal compounds by treating the mineral slurry by a
pyrometallurgical extraction treatment adapted to remove the metal
compounds.
15. The process for producing metal compounds directly from
underground mineral deposits according to claim 14, where the
mineral slurry is transported by a device selected from a group
consisting of truck, rail, pipeline, and a combination of two or
more thereof.
16. The process for producing metal compounds directly from
underground mineral deposits according to claim 14 further
comprising the step of: prior to the step of physically separating
the mineral slurry, grinding particulate in the mineral slurry to a
particle size of about 80% smaller than 100 mesh.
17. The process for producing metal compounds directly from
underground mineral deposits according to claim 14, further
comprising the step of: after the step of physically separating the
mineral slurry, mixing the mineral slurry with at least one
reducing agent selected from a group consisting of coal, coke,
coke-breeze, char, reducing sugar, molasses, and a combination of
two or more thereof.
18. The process for producing metal compounds directly from
underground mineral deposits according to claim 14, further
comprising the step of: after the step of physically separating the
mineral slurry, mixing the mineral slurry with at least one
additive selected from a group consisting of calcium oxide,
limestone, soda ash, Na.sub.2CO.sub.3, NaHCO.sub.3, NaOH, borax,
NaF, fluorspar, CaF.sub.2, aluminum smelting industry slag and a
combination of two or more thereof.
19. The process for producing metal compounds directly from
underground mineral deposits according to claim 14, where the step
of removing metal compounds is performed in a rotary hearth furnace
in a reducing atmosphere.
Description
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/695,045 filed Jan. 27, 2010, which claims
the benefit of U.S. Patent Application 61/147,502, filed on Jan.
27, 2009, which is incorporated herein by reference.
BACKGROUND AND SUMMARY
[0002] Mineral deposits containing metal compounds from which metal
products can be made are presently found in various geographic
locations and in ore veins of quite varying depth. The mineral
deposits in the past have been removed from such ore veins either
by open pit mining or shaft mining. In locations where the mineral
deposit is located close to the surface of the earth, the
overburden is removed by excavation to reach the ore deposit and
the ore removed by open pit mining. This type of mining typically
involves using very large and expensive draglines or other
excavating equipment to remove the overburden and the ore deposit.
Where the ore vein is deeper in the earth so that it is not
practical to remove the overburden to reach the mineral deposits,
shaft mines are employed by digging tunnels and shafts so that
miners and equipment can reach the ore deposit, and the ore deposit
removed by the miners and equipment through the tunnels and/or
shafts.
[0003] With either open pit or shaft mining, the mineral deposit
must be of such depth to make it economical to either remove the
overburden or dig the tunnel and shafts to reach the ore deposit.
Additionally, ore veins underground vary in depth along their run,
and as a result, the mining only continues to where the depth of
the ore vein narrows to the point where the overburden can no
longer be economically removed or the ore deposit can no longer be
reached underground with miners and available equipment. These
factors have greatly limited the ore deposits that can be
commercially removed from the ground.
[0004] Furthermore, open pit mining and shaft mining have been
criticized for both immediate and ongoing environmental concerns,
including their impact on erosion, surface and underground water
quality, and the aesthetic impact on mined and surrounding
landscape and land values. Further, many mineral deposits exist
beneath areas that are environmentally sensitive areas such as
national or state parks, pristine lakes, recreational areas, urban
areas, wetlands, and pristine and used surface areas where permits
cannot presently be obtained to remove underground mineral
deposits. These latter mineral deposits have been before now
inaccessible because the prior methods available for removing the
mineral deposits impacted the local environment and/or potentially
damaged the natural or manmade resource above the mineral deposit.
Increasing awareness of environmental concerns and desire to
maintain various natural resources alone has caused fewer permits
for removal of desired mineral deposits to be granted.
[0005] Additionally, whether open pit or shaft mining is employed,
ore removed from underground mineral deposits had to be processed
to remove desired metal or metal compounds at the mine site. In the
past, transporting ores from the mine site was not possible for a
commercially viable mining operation. Such processing of the ore
from the mineral deposit exacerbated the environmental impact by
the need to process the removed ore at the mine site. Processing of
the ore at the mine site may involve separation of the useful
metals and metal compounds from undesirable minerals also present
in the mineral deposit with environmentally sensitive chemicals.
Such processing also likely involved storage or disposal of various
mine wastes at the mine site on an ongoing basis.
[0006] Accordingly, there remains a need for a method of producing
metals and metal compounds from mineral deposits that were not
previously commercial accessible because of the costs of reaching
the ore vein, or that the nature of the land areas under which the
ore vein lie made it environmental impermissible to remove the
desired ore deposit.
[0007] Disclosed herein is a process for producing metal product
directly from mineral deposits without open pit or shaft mining.
This process is particularly useful in removing manganese-bearing
deposits and other similar mineral deposits where the ore in the
mineral deposit can be formed directly into a slurry by injection
of water under pressure into the mineral deposit. In some cases,
explosives or other means may be used in addition to the water
pressure to break up the mineral deposit and facilitate removal to
the mineral deposit in a water slurry through a borehole. The
method also includes transporting to a remote location, as well as
processing the formed and extracted water slurry at the remote
location to form a product of metal compounds that can be further
processed in a furnace or other facility.
[0008] For removal and processing of metal-bearing ore deposits
from an environmentally sensitive location, the present method may
comprise the steps of:
[0009] (a) forming a borehole from an accessible site into a
mineral deposit containing metal compounds;
[0010] (b) inserting a slurry-forming device having a nozzle into
the borehole adapted to direct pressurized water through the nozzle
into the mineral deposit;
[0011] (c) supplying pressured water through the nozzle of the
slurry-forming device into the mineral deposit forming a mineral
slurry containing the metal compounds from the mineral deposit;
[0012] (d) extracting the mineral slurry containing the metal
compounds through the borehole;
[0013] (e) transporting the mineral slurry away from the borehole
to a location remote from the site;
[0014] (f) leaching the extracted mineral slurry at the remote
location to convert the metal compounds to a soluble form in a
leach solution; and
[0015] (g) removing metal compounds by treating the leach solution
with an extraction treatment adapted to remove the metal
compounds.
[0016] Additionally, in the transporting step the mineral slurry
may be transported in removed form or after partial water removal.
This transporting step is particularly useful in removing mineral
deposits from environmental sensitive areas and, in any event, may
be used in allowing the leaching and removal steps to be performed
at one location on mineral slurries extracted through a number of
boreholes in different parts of the same or different ore veins.
The mineral slurry may be transported by at least one device
selected from a group consisting of truck, rail, and pipeline to
the remote location where the leaching and removal steps are
performed.
[0017] The present process for producing metal compounds may be
used for mining mineral deposit containing oxides of at least one
metal selected from the group consisting of manganese, cobalt,
copper, iron, chromium, lead, nickel, magnesium, platinum,
palladium, gold, silver, aluminum, lithium, molybdenum, tungsten,
uranium, vanadium, zinc, and zirconium.
[0018] The pressure of the injected water may be any desirable or
useful pressure effective to form the mineral slurry of the
manganese mineral deposit in a particular ore vein. The water
pressure, for example, may be between 1000 and 2500 pounds per
square inch (psi). The method is useful with ore veins from narrow
depths up to several hundred feet in depth. Similarly, the method
is commercially feasible with ore veins that vary widely in depth,
thus permitting removing of ore from mineral deposits not
previously possible and to an extent not previously possible.
[0019] The present method may be used for producing metal products
directly from underground mineral deposits that are capable of
being broken up by the slurry-forming device to create the mineral
slurry. The method may involve, where desired and permissible,
detonating explosives or using other auxiliary devices in the
underground mineral deposit to assist in breaking-up the ore
deposit and forming the water slurry.
[0020] In one alternative, the method may be used also by forming
more than one borehole where the first borehole is generally
vertical from the surface into the mineral deposit and the second
borehole is slanted so as to intersect the first bore in the ore
deposit. The slurry-forming device can be inserted through the
second slant borehole to increase the range to which water can be
injected under pressure into the ore body, and the formed mineral
slurry can be removed from the ore deposit through the first bore
hole. This embodiment may increase the range of the removal of ore
from certain ore veins through a borehole site. Alternatively, the
first borehole may be partially predrilled in a slant borehole to
allow the range of removal of mineral deposits from the ore vein
from a given borehole site.
[0021] The method may include, before leaching, and either before
or after performance of the transporting step, a step of grinding
particulate matter in the extracted mineral slurry to a particle
size of about 80% smaller than 100 mesh, or about 80% smaller than
200 mesh.
[0022] The step of leaching the mineral slurry may include leaching
the mineral slurry with acids to put desired metal compound into
solution. For example, with extracted mineral slurry of the metal
oxides of manganese, the acid may be sulfurous acid
(H.sub.2SO.sub.3) formed by dissolving SO.sub.2 in water.
Additionally, the leach solution may include at least one reducing
agent selected from a group consisting of SO.sub.2, carbon,
reducing sugar, molasses, and a combination of two or more thereof.
The leach solution may have a pH of 3 or below.
[0023] After the step of leaching the mineral slurry placing
desired metal compounds in solution, the process may include the
step of chemically treating the leach solution with oxidizing
agents to produce manganese oxide and/or other metal products.
Alternatively or in addition, the process may include the step of
chemically treating the leach solution with reducing agents
producing metallic manganese.
[0024] After the step of leaching the extracted mineral slurry, the
process may include the step of treating the leach solution with
one or more treatments to remove selected metals or other metal
compounds. Additionally, the step of removing metals and/or metal
compounds of manganese may comprise electrochemically plating the
manganese metal product out of solution or treating the leach
solution to precipitate the manganese metal product from
solution.
[0025] Alternatively, the extracted mineral slurry may be processed
by pyrometallurgical processes to remove the metal compounds from
the mineral slurry. In this alternative, the process for producing
metal compounds directly from underground mineral deposits in an
environmentally sensitive location may include the steps of:
[0026] (a) forming a borehole from an accessible site into a
mineral deposit containing metal compounds;
[0027] (b) inserting a slurry-forming device having a nozzle into
the borehole adapted to direct pressurized water through the nozzle
into the mineral deposit;
[0028] (c) supplying pressured water through the nozzle of the
slurry-forming device into the mineral deposit forming a mineral
slurry containing the metal compounds from the mineral deposit;
[0029] (d) extracting the mineral slurry containing the metal
compounds through the borehole;
[0030] (e) transporting the mineral slurry away from the borehole
to a location remote from the site;
[0031] (f) physically separating the extracted mineral slurry at
the remote location; and
[0032] (g) removing metal compounds by treating the mineral slurry
by a pyrometallurgical extraction treatment adapted to remove the
metal compounds.
[0033] Prior to the step of physically separating the mineral
slurry, the process may include grinding particulate in the mineral
slurry to a particle size of about 80% smaller than 100 mesh, and
may include grinding to a particle size of about 80% smaller than
200 mesh. After the step of physically separating the mineral
slurry, water may be removed from the mineral slurry and the
resulting ore material then mixed with at least one reducing agent
selected from a group consisting of coal, coke, coke-breeze, char,
reducing sugar, molasses, and a combination of two or more thereof.
Alternatively or in addition, water may be removed from the mineral
slurry and the ore material may be mixed with at least one additive
selected from a group consisting of calcium oxide, limestone, soda
ash, Na.sub.2CO.sub.3, NaHCO.sub.3, NaOH, borax, NaF, fluorspar,
CaF.sub.2, aluminum smelting industry slag and a combination of two
or more thereof.
[0034] The step of removing metal compounds may be performed in a
rotary hearth furnace. Alternatively, the step of removing metal
compounds may be performed in an electric arc furnace, a blast
furnace, or an induction furnace.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a flow chart showing steps of a method for
producing metal from a mineral deposit; and
[0036] FIG. 2 is a diagrammatical partial section view of a
borehole mining operation.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0037] Referring now to FIG. 1, a method is disclosed for producing
metals and metal compounds that may be used to extract metal
products from environmentally sensitive areas. As shown in FIG. 1,
the method may include steps of: [0038] (a) forming a borehole at
an accessible site into a mineral deposit, the mineral deposit
containing metal oxides such as metal oxides of manganese; [0039]
(b) inserting a slurry-forming device having a nozzle into the
borehole, the device adapted to directing pressurized water through
the nozzle into the mineral deposit; [0040] (c) supplying pressured
water through the nozzle into the mineral deposit; [0041] (d)
forming a mineral slurry containing metal oxides, such as metal
oxides of manganese; [0042] (e) extracting the mineral slurry
through the borehole to the surface; [0043] (f) optionally,
separating water from the extracted mineral slurry, which may be
recycled to a water storage tank; [0044] (g) optionally, forming a
filter-cake of the mineral slurry having a water content of between
about 8% and 10%; [0045] (h) transporting or conveying the mineral
slurry to a processing location; [0046] (i) leaching the mineral
slurry to convert the metal oxides to a soluble form in a leach
solution; and [0047] (j) removing metal compounds of manganese by
treating the leach solution with an extraction treatment adapted to
remove metal products, or other hydrometallurgical leaching
techniques to extract metal products.
[0048] Alternatively, instead of removing metal compounds from a
leach solution, desired metal compound may be removed from the
mineral slurry using pyrometallurgical processes. After
transporting, as shown in the alternative process in FIG. 1, the
process may include steps of upgrading the mineral slurry by
physical separation. After de-watering the mineral slurry, the
resultant ore material may be processed using pyrometallurgical
extraction as discussed below.
[0049] The present method involves first forming a bore hole into a
mineral deposit with suitable drilling equipment at a select
borehole site that is environmentally permitted, and lowering into
the mineral deposit through the borehole a slurry-forming device
having a nozzle through which pressurized water can be injected
into the mineral deposit. For removal of manganese-bearing ore from
such a mineral deposit, the water pressure may be between 1000 and
2500 psi. In any event the pressurized water should be sufficient
to break up the ore in the mineral deposit and form a mineral
slurry that can be pumped through the borehole to the surface at
the borehole site. The range of extraction of ore from the mineral
deposit will depend on the softness of the mineral deposit and the
extent and direction of the water pressure. The slurry-forming
device may permit the nozzle to be controlled and directed in any
desired direction, and the nozzle may be rotated about the axis of
the borehole to carve out an approximately circular work area in
the ore vein around the borehole, and may be moved along the
borehole to extend the work area and volume of ore removed from the
borehole site.
[0050] The present method is effective where the mineral deposit is
in friable form, granular form, or other form capable of being
broken up by the pressurized water from the slurry-forming device
to create the mineral slurry. Higher pressure water may be used for
harder or denser mineral deposits, or where a larger work area of
extraction may be desired from a borehole. In some cases,
explosives or other supplemental means may be used where desired
and permissible to assist the water pressure in forming the mineral
slurry in the mineral deposit.
[0051] In one embodiment, the method could be performed with the
mineral deposit of metal compounds of manganese formed in an
mineral deposit about 200 feet to 400 feet beneath the surface of
an overburden in the Emily District of Minnesota, where the mineral
deposit contains manganese ore including pyrolusite (MnO.sub.2) and
magnanite (MnO(OH)). Such manganese deposits may contain
"sand-like" particles in a granular form capable of being broken up
by water at a pressure between about 1000 and 2500 psi. In
alternative locations, the mineral deposit may contain oxides of
manganese, cobalt, copper, iron, chromium, lead, nickel, magnesium,
platinum, palladium, gold, silver, aluminum, lithium, molybdenum,
tungsten, uranium, vanadium, zinc, and zirconium.
[0052] As shown in FIG. 2, a borehole drilling device 10 may
include a hydraulic slurry-forming device 20 having a nozzle 22
inserted into a desired work area 24 in a mineral deposit through
casing pipe 30. The borehole drilling device 10 may have a drill
bit 40 at its lower end adapted to bore a borehole cavity 42 that
is somewhat larger in diameter than the hydraulic slurry-forming
device 20 and the casing pipe 30. As shown in FIG. 2, the drilling
device 10 may drill through the cap rock 44, through the desired
work area 24 in the mineral deposit, and into the bedrock 46
forming a sump 48. An eductor section 50 is positioned in the
casing pipe 30 below the hydraulic slurry-forming device 20. An
inner pipe 60 extends through the casing pipe 30 in connection with
the eductor section 50 and forming annular conduit 70 between the
inner pipe 60 and the casing 30, which is in connection with the
nozzle 22 of the slurry-forming device. The casing pipe 30 and
inner pipe 60 extend from an work area in a mineral deposit, to the
surface, and may be formed by connecting a plurality of pipe
sections end to end. The inner pipe 60 forms an outlet slurry
passage for removing the mineral slurry from the mineral deposit,
and the conduit 70 forms an inlet water passage for delivering
water 72 to the nozzle 22 of the slurry-forming device 20 in the
mineral deposit.
[0053] A pump 80 is provided in connection with the annular conduit
70 for delivering pressurized water into the conduit 70 to the
hydraulic slurry-forming device 20. In operation, the pump may
provide between about 400 and 1000 gallons per minute (gpm) water
flow. In one alternative, the pump provides 750 gpm of water at
2500 psi to the nozzle 22 of the slurry-forming device. The
pressurized water flow, which may be fitted with a suitable
regulator, is directed through the nozzle 22 into the work area in
the mineral deposit transverse to the borehole. As the water passes
through the nozzle 22, the flow accelerates to a flow sufficiently
powerful to break and scale away the ore from the mineral deposit
in the work area 24 to form a mineral slurry 82. The water pressure
through the nozzle 22 may be regulated between about 1500 and 2500
psi. Alternatively, the water pressure through the nozzle 22 may be
regulated between about 800 and 1500 psi. The loosened material
from the mineral deposit is fluidized through mixing with the
injected water to form the mineral slurry 82 in the work area.
[0054] The upper end of the drilling device 10 may include a swivel
joint 100 and turntable 102 capable of rotating at least a portion
of the drilling device. The drilling device may be supported by a
suspension 104 such as a crane, derrick, or other suspension. In
operation, the drilling device may be rotated to turn the drill bit
40 for extending the borehole into the mineral deposit.
Alternatively or in addition, the hydraulic slurry-forming device
20 may be rotated for rotating the nozzle 22 in an approximately
circular cutting path around the borehole. By rotating the nozzle
around the axis of the borehole, and by raising and lowering the
nozzle in the borehole, an approximately cylindrical shaped work
area cavity 110 may be formed around the borehole in the mineral
deposit 24 by the pressurized water flow 72 fluidizing material
from the deposit and forming the mineral slurry 82 for
extraction.
[0055] Water pumped through the inlet water conduit 70 toward the
work area that does not exit the nozzle is directed to the eductor
50 having a discharge into the inner pipe 60. The flow of water
through the eductor 50 provides suction to draw mineral slurry from
the work area into the inner pipe 60. The mineral slurry and water
are sucked through an inlet into the inner pipe 60 and transported
up to the surface at the borehole site through the inner pipe 60.
The mineral slurry may be directed to a clarifier tank 90 or other
suitable container at the borehole site where water may be removed
and the slurry concentrated. As the mineral particulate settles to
the bottom of the tank 90, water may be filtered from the tank and
pumped back to the work area in the mineral deposit through the
conduit 70. By re-using the water, make-up water may be reduced to
a minimum and the method becomes even more environmental capable as
essentially a closed loop system for removing the mineral slurry
from the mineral deposit. In one example, additional water use in
operation of the formation and removal of the mineral slurry was
limited to 1000 gallons per day. Water may be supplied in a water
storage tank, not shown, such as a 20,000 or 40,000 gallon storage
tank.
[0056] In one embodiment, the flow rate of mineral slurry through
the inner pipe 60 may be between about 400 and 800 gpm, which may
be directed to the clarifier tank 90. The extracted mineral slurry
may be between about 10% and 20% solids, and may be greater than
20%. For certain mineral deposits, the extracted mineral slurry may
be less than 10% solids.
[0057] For larger mineral deposits or directional ore veins, a
directional borehole may be formed slanted and/or extended
generally horizontally through the ore vein. In certain directional
boreholes, the slurry-forming device may be moved along the
borehole without being rotated. Also, a plurality of deviated
boreholes may be drilled from one "mother" bore, each deviated
borehole extending the inclination and/or horizontal reach into the
mineral deposit as desired to increase the volume of removed
mineral ore.
[0058] The overall structure and operation of a borehole drilling
apparatus and slurry-forming device may be as described in U.S.
Pat. Nos. 4,059,166, 6,460,936, and 6,688,702, the disclosures of
which are incorporated herein by reference for appropriate
constructional and operational details for purpose of best mode of
carrying out the method of the present disclosure.
[0059] The method may be used also by forming a first borehole
substantially vertically from the surface into the mineral deposit
and a second borehole slanted so as to intersect the first bore in
the mineral deposit, not shown. The slurry-forming device may be
inserted through the second slant borehole to increase the range to
which water can be injected under pressure into the mineral
deposit, and the formed mineral slurry can be removed from the
mineral deposit through the first bore hole. For certain mineral
deposits, this embodiment may increase the range of the removal of
metal compounds from the ore deposit.
[0060] In another alternative, a plurality of boreholes may be
provided for water injection and at least one borehole provided for
mineral slurry extraction. In one embodiment, not shown, four
boreholes are provided for water injection, arranged approximately
in quadrants of a work area. An extraction borehole is provided in
approximately centrally located in the work area, as desired, for
extraction of slurry. The extraction borehole may not be as deep
as, or may be deeper than the boreholes through which water is
injected into the mineral deposit.
[0061] In any case, after the mineral slurry is extracted from the
mineral deposit through one of the boreholes or the inner pipe 60
of a given borehole, the mineral slurry is processed to remove the
desired metal products. In clarifier tank 90, for example, water
from the mineral slurry may be filtered, removed and recycled. The
mineral slurry may pass through a screen such as a screen having
1/16 inch openings to screen out larger ore pieces. Then additional
water may be removed using a cyclone, settling tank, and/or a
thickener tank which increases the solids in the slurry from about
10% solids to between about 45% and 75% solids. The mineral slurry
may be further dewatered in a filter press to form a filter cake of
mineral slurry having a moisture content between about 8% and 10%.
Alternatively, the moisture content of the filtered mineral slurry
may be less than 8% or more than 10% as desired in the particular
embodiment. The water removed from the mineral slurry may be pumped
into the water storage tank, or may be pumped back to the work area
of the mineral deposit through annular conduit 70.
[0062] During the mining process, slightly more water may be
extracted with the mineral slurry from the mineral deposit than is
injected through the nozzle. A net withdrawal of water from the
work area produces a "cone of depression" in the work area. The
depression may enable an inflow or migration of pre-existing
underground water towards the borehole area that enables mineral
slurry to flow toward the work area. The cone of depression may
slow the outflow of mineral slurry away from the work area.
[0063] For extracting minerals from environmentally sensitive and
other areas, the extracted mineral slurry is transported away from
the mine site to be processed at a remote location as discussed
below. The mineral slurry, either as extracted from the mineral
deposit or after concentration, may be transported by truck, rail,
pipeline, or a combination thereof to the remote location to remove
the desired compounds.
[0064] To remove the desired compounds, the mineral slurry may be
processed to form a leaching solution from which the desired metal
compounds and other metal products may be removed. Alternatively,
the desired compounds may be removed from the mineral slurry by a
pyrometallurgical process. The process of removing desired
compounds from the mineral slurry may be performed at the borehole
site as desired and permitted, or may be performed at the remote
location.
[0065] Optionally, prior to leaching, or pyrometallurgical
processing discussed below, the process may include grinding or
otherwise reducing the particle size of the ore in the mineral
slurry to a particle size of about 80% less than 100 Tyler mesh, or
a particle size of 80% less than 200 Tyler mesh.
[0066] In one embodiment, the manganese mineral forms include
pyrolusite (MnO.sub.2) and magnanite (MnO(OH)) having the
consistency of "sand-like" particles having a particle size in the
range of about 10 mesh to about 500 mesh. In this deposit, the
particles are porous, fine particles that may not require further
grinding, and may need little preparation before the step of
leaching of the ore to form a leaching solution from which
manganese metal may be extracted.
[0067] The mineral slurry may be leached to convert the metal
oxides to a soluble form in a leach solution. The leach solution
may be formed in a suitable leaching tank such as a tank having
stifling blades, or other stirred tank. The stirred tank may be
adapted to a continuous leaching process, or may be adapted to a
batch process.
[0068] The leach solution may be formed with approximately 10%
manganese in an acidic solution. For leaching some mineral ores,
the leach solution may include between about 10% and 80% manganese.
Alternatively, the leach solution may include between about 5% and
10% manganese.
[0069] Leaching may be conducted using SO.sub.2 gas, which acts
with water to form sulfurous acid (H.sub.2SO.sub.3) to render the
metal compounds in the minerals soluble in solution. SO.sub.2 gas
may be introduced into the stirred mineral slurry through diffusers
or spargers placed below the tank stirring blades. The SO.sub.2 gas
is passed through the manganese leach solution to a pH of about 1.
The leach solution may have between about 5% and 8% SO.sub.2 at a
pH of about 1. The SO.sub.2 addition is controlled to maintain the
pH of about 1 for a processing period of about 10 minutes, after
which time about 95% or more of the manganese is in solution.
Alternatively, sulfuric acid (H.sub.2SO.sub.4) may be used to form
the acidic leach solution with similar pH and percent manganese in
solution. In any case, the manganese leaching process is conducted
at ambient temperature and atmospheric pressure in the leaching
tank.
[0070] A reducing agent may be provided in the leach solution. The
reducing agent may be SO.sub.2, carbon, reducing sugar, molasses,
or other reducing agents. The reducing agents reduce the oxidation
state of the metal oxides in solution, such as from Mn(4+) to
Mn(2+).
[0071] The manganese (Mn(2+)) in the acidic leach solution may be
MnSO.sub.4. The leach solution may be chemically treated with
oxidizing agents to produce metal compounds, such as metal oxides.
The manganese leach solution may be treated with an oxidizing
agent, such as H.sub.2O.sub.2, NaOCl, KMnO.sub.4, or
Na.sub.2S.sub.2O.sub.8 or other oxidizing agent to form chemical
manganese dioxide (MnO.sub.2), or CMD in solution. Alternatively,
the MnSO.sub.4 may be electrochemically oxidized to form
electrolytic manganese dioxide, or EMD in solution. In yet another
alternative, the MnSO.sub.4, may be dried and crystallized to form
chemical grade MnSO.sub.4 or fertilizer grade MnSO.sub.4.
[0072] In yet another alternative, the process may include the step
of chemically treating the leach solution with reducing agents
producing metallic manganese. Then, electrochemically treating the
leach solution to plate out metallic manganese. The extraction
treatment may be an electrochemical treatment, such as
electroplating the desired metal onto a cathode.
[0073] After the desired metal compounds or other metal products
are extracted from the leach solution, the leach solution may be
reconditioned to the desired pH and reused to process subsequent
batches of mineral slurry. Mineral solids and solutions left over
from the leaching process may be neutralized, if necessary with
lime or limestone, for use or disposition. Alternatively, the leach
solution may be further used for secondary processes. For example,
the use of SO.sub.2 gas dissolved in water produces a sulfate,
which can be used to make ammonium sulfate fertilizer. After the
desired metal products are removed from the leach solution, ammonia
may be added to form the ammonium sulfate.
[0074] As discussed above, the present methods may be used to make
metal products directly from underground mineral deposits other
than manganese where the ore vein can be broken up to form a
mineral slurry. This method may be suitable for use in making
oxides of cobalt, copper, iron, chromium, lead, nickel, magnesium,
platinum, palladium, gold, silver, aluminum, lithium, molybdenum,
tungsten, uranium, vanadium, zinc, and zirconium directly from
underground mineral deposits.
[0075] For ore from some mineral deposits, the leach solution may
have a pH of about 3 or lower, and in certain alternatives may have
a pH of about 5 or lower. Additionally, certain ores from mineral
deposits may be in the leach solution at temperatures and pressures
higher than ambient to render the minerals soluble.
[0076] Some ores form mineral deposits containing a plurality of
metals, each having certain extraction techniques the present
method may be used to make two or more metal products of different
metals from the mineral slurry. The mineral slurry may require
multiple treatments each adapted to removing specific metal
products from the mineral slurry depending upon the composition of
the extracted ore. In some cases, certain leach solution treatments
may be used to remove undesired or other metals and metal compounds
that would contaminate the desired metal compound or other desired
metal products. In other cases certain leach solution treatments
may recover metal products for sale or use depending in part on
market prices. For example, certain manganese ore deposits contain
various amounts of other metals and compounds such as iron, silica,
and alumina which may be recovered if present in sufficient
quantities to make recovery commercially viable.
[0077] For example, iron may be removed from the leach solution by
raising the pH of the solution to about 5 or greater by the
addition of lime or other base, then adding an oxidizing agent,
such as manganese oxide or other oxidizer to form an iron
precipitate. The iron precipitate may then be filtered from the
solution as a metal product.
[0078] In another example, where a leach solution is formed
containing nickel and manganese, it may be desired that nickel
remain in solution and manganese be removed. The manganese may be
precipitated from the leach solution by an addition such as ammonia
and carbon dioxide, which forms MnCO.sub.2. The manganese
precipitate may be filtered from the solution to form the metal
product.
[0079] Amounts of heavy metals such as nickel, arsenic, lead,
cobalt, and other heavy metals found in the ores may be removed
from a leaching solution form from the mineral slurry by adding
sulfide to the leach solution to form precipitates that may be
filtered from the solution to form the metal product.
[0080] Other impurities and undesired metals and compounds may be
found in the mineral ore which may be from a leaching solution form
from the mineral slurry. Various chemical treatments may be applied
as desired to remove the metal products from the leach solution. It
is contemplated that the leach solution may be heated to a desired
temperature and pressure according to the chemical treatment
applied to form the desired metal products.
[0081] In some embodiments, after impurities and undesired
compounds and metals are precipitated from the solution, the leach
solution may be treated with chemical or electrochemical techniques
to plate out the desired metal compounds or other metal products
from solution. Also, to produce a metallic state, reducing agents
may be provided in the leach solution. The reducing agents may be
SO.sub.2, carbon, reducing sugar, molasses, or other reducing
agents. Alternatively, the leach solution may be chemically treated
with oxidizing agents to produce metal products, such as metal
oxides.
[0082] In an alternative process, the mineral slurry may be
processed using pyrometallurgical extraction methods to remove the
certain metal compounds from the mineral slurry. The process may
include grinding or otherwise reducing the particle size of the ore
in the mineral slurry to a particle size of about 80% less than 100
Tyler mesh, or to a particle size of 80% less than 200 Tyler mesh.
To increase the concentration of desired metal compounds in the
mineral slurry, the mineral slurry may be upgraded using physical
separation processes to separate tailings such as rock and other
separable products from the slurry. The mineral slurry may be
upgraded using physical separation such as high intensity magnetic
separation, gravity separation, floatation, or other separators as
desired. In some applications for processing at a location remote
from the borehole site, the mineral slurry may be de-watered for
transportation. For grinding and physical separation processes the
mineral slurry may be reslurrified as desired.
[0083] After the step of physically separating the mineral slurry,
the upgraded mineral slurry is de-watered, and the resulting ore
material may be mixed with one or more reductants. The reducing
agents may be selected from a group consisting of coal, coke,
coke-breeze, char, reducing sugar, molasses, and a combination of
two or more thereof. Alternatively or in addition, the mineral
slurry is de-watered, and the resulting ore material mixed with at
least one additive selected from a group consisting of calcium
oxide, limestone, soda ash, Na.sub.2CO.sub.3, NaHCO.sub.3, NaOH,
borax, NaF, fluorspar, CaF.sub.2, aluminum smelting industry slag
and a combination of two or more thereof. The ore material mixture
may then be fed into a furnace for extracting the desired metal
compound. The furnace may be an electric arc furnace, blast
furnace, induction furnace, or rotary hearth furnace at a
temperature selected for the desired metal compound.
[0084] In one application, a mineral slurry containing manganese
ore may be processed in a rotary hearth furnace between
approximately 1100 and 1300.degree. C. The de-watered manganese ore
material may be mixed with a reductant such as coal and a fluxing
agent such as limestone. Optionally, the manganese ore material may
be formed into briquettes. The manganese slurry may be processed in
the furnace to produce ferromanganese and/or silicomanganese, with
other compounds and tailings separating as slag.
[0085] As discussed above, the mineral slurry may be processed at
the borehole site or transported away from the borehole site to be
processed at a remote location. The mineral slurry may be
transported by truck, rail, pipeline, or a combination thereof as
extracted from the mineral deposit or after removing part of the
water from the slurry. By transporting the mineral slurry to a
location remote from the borehole site, the use chemicals, such as
sulfurous acid and sulfuric acid in the leaching step may be
managed in a location more environmentally suited to chemical
processing. Further, by including the transportation step in the
method, one leaching and metal product recovery facility can
service multiple borehole sites and a large volume of mineral
slurry, vastly increasing the productivity of the method in making
metal products directly from underground mineral deposits.
[0086] In one embodiment, the mineral slurry is transported to the
processing location in water tight dump trucks such as a 20 ton
covered side dump trucks. Prior to transporting, the concentrated
mineral slurry may be formed into filter cakes, the filter cakes
being loaded directly into trucks or onto railcars. Alternately,
the filter cakes may be loaded into ore bags such as 2000 lb water
tight sacks, which may be transported by truck or rail. In one
alternative, the mineral slurry is not formed into a filter cake
and is transported by pipeline, the mineral slurry having a solids
content about 50% or greater.
[0087] The presently disclosed process may be used to recover metal
products directly from mineral deposits under environmentally
sensitive geographic areas. The process may include the steps of
forming a borehole into a mineral deposit of ore containing metal
compounds, inserting a slurry-forming device having a nozzle into
the borehole adapted to direct pressurized water through the nozzle
into the mineral deposit, supplying pressured water through the
nozzle into the mineral deposit forming a mineral slurry from an
ore vein, and extracting the mineral slurry through the borehole.
Then, transporting the mineral ore containing metal oxides away
from the borehole to a location remote from the borehole site,
leaching the metal oxides at the remote location to convert the
metal oxides to a water soluble form in a leach solution, and
removing metal compounds and other metal products by treating the
leach solution with an extraction treatment adapted to remove the
metals and/or metal compounds.
[0088] By transporting the mineral ore away from the mine site,
chemicals used at the borehole site and needed facilities may be
substantially reduced. The slurry formation step may use water
without chemical or other additions. The water may be taken from
groundwater or surface sources. Additionally, it is contemplated
that the water may be returned to the environment with little
cleaning or water treatment required. By using the disclosed
process and transporting the mineral slurry away from the mine
site, valuable mineral deposits may be extracted in environmentally
sensitive areas with insignificant impact on the overlying surface
area.
[0089] While the invention has been illustrated and described in
detail with reference to the figures and foregoing description, the
same is to be considered as illustrative and not restrictive in
character, it being understood that one skilled in the art will
recognize, and that it is the applicants' desire to protect, all
aspects, changes and modifications that come within the spirit of
the invention.
* * * * *