U.S. patent application number 14/658795 was filed with the patent office on 2015-07-02 for composition for treating an excavation activity.
This patent application is currently assigned to GOLDER ASSOCIATES INC.. The applicant listed for this patent is John C. Fodor, James J. Gusek, Brian P. Masloff. Invention is credited to John C. Fodor, James J. Gusek, Brian P. Masloff.
Application Number | 20150183009 14/658795 |
Document ID | / |
Family ID | 47712758 |
Filed Date | 2015-07-02 |
United States Patent
Application |
20150183009 |
Kind Code |
A1 |
Gusek; James J. ; et
al. |
July 2, 2015 |
COMPOSITION FOR TREATING AN EXCAVATION ACTIVITY
Abstract
A composition for treating an excavation activity includes a
reagent suspended in foam to form a reagent-foam mixture. The
reagent is selected to react with at least one of sulfides or
bacteria in waste rock or tailings materials to reduce acid rock
drainage. The reagent includes at least one of limestone, dolomite,
sodium bicarbonate, steel slag, fly ash, or sodium hydroxide.
Inventors: |
Gusek; James J.; (Lakewood,
CO) ; Masloff; Brian P.; (Golden, CO) ; Fodor;
John C.; (Golden, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gusek; James J.
Masloff; Brian P.
Fodor; John C. |
Lakewood
Golden
Golden |
CO
CO
CO |
US
US
US |
|
|
Assignee: |
GOLDER ASSOCIATES INC.
Lakewood
CO
|
Family ID: |
47712758 |
Appl. No.: |
14/658795 |
Filed: |
March 16, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13211074 |
Aug 16, 2011 |
8985902 |
|
|
14658795 |
|
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Current U.S.
Class: |
405/264 ;
405/263 |
Current CPC
Class: |
E21F 15/005 20130101;
B09B 3/0016 20130101; B09C 1/08 20130101; B09C 1/02 20130101; C09K
8/605 20130101; E21B 33/138 20130101; E21F 15/08 20130101; C09K
8/94 20130101; B09C 1/10 20130101 |
International
Class: |
B09C 1/08 20060101
B09C001/08; B09B 3/00 20060101 B09B003/00; B09C 1/10 20060101
B09C001/10 |
Claims
1. A composition for treating an excavation activity, comprising:
a. a reagent suspended in foam to form a reagent-foam mixture,
wherein said reagent is selected to react with at least one of
sulfides or bacteria in waste rock or tailings materials to reduce
acid rock drainage; and b. wherein said reagent comprises at least
one of limestone, dolomite, sodium bicarbonate, steel slag, fly
ash, or sodium hydroxide.
2. The composition as in claim 1, wherein said foam comprises at
least one of sodium lauryl sulfate, ammonium lauryl sulfate, or
sodium laureth sulfate, or natural surfactants derived from animal
proteins.
3. The composition as is claim 1, wherein said reagent-foam mixture
comprises less than approximately 10 percent by volume of
reagent.
4. The composition as in claim 1, wherein said reagent comprises
carbon dioxide or an inert gas that displaces oxygen.
5. The composition as in claim 1, wherein said reagent comprises at
least one of milk, sodium thiocyanate, bio-solids, sawdust, paper,
or composted animal manure.
6. The composition as in claim 1, wherein said reagent comprises at
least one of iron, copper, manganese oxide, zeolite minerals, peat,
activated carbon, or organic resins.
7. A composition for treating an excavation activity, comprising:
a. a reagent suspended in foam to form a reagent-foam mixture,
wherein said reagent is selected to react with at least one of
sulfides or bacteria in waste rock or tailings materials to reduce
acid rock drainage; and b. wherein said reagent comprises at least
one of milk, sodium thiocyanate, bio-solids, sawdust, paper, or
composted animal manure.
8. The composition as in claim 7, wherein said foam comprises at
least one of sodium lauryl sulfate, ammonium lauryl sulfate, or
sodium laureth sulfate, or natural surfactants derived from animal
proteins.
9. The composition as is claim 7, wherein said reagent-foam mixture
comprises less than approximately 10 percent by volume of
reagent.
10. The composition as in claim 7, wherein said reagent comprises
carbon dioxide or an inert gas that displaces oxygen.
11. The composition as in claim 7, wherein said reagent comprises
at least one of iron, copper, manganese oxide, zeolite minerals,
peat, activated carbon, or organic resins.
12. A composition for treating an excavation activity, comprising:
a. a reagent suspended in foam to form a reagent-foam mixture,
wherein said reagent is selected to react with at least one of
sulfides or bacteria in waste rock or tailings materials to reduce
acid rock drainage; and b. wherein said reagent comprises at least
one of iron, copper, manganese oxide, zeolite minerals, peat,
activated carbon, or organic resins.
13. The composition as in claim 12, wherein said foam comprises at
least one of sodium lauryl sulfate, ammonium lauryl sulfate, or
sodium laureth sulfate, or natural surfactants derived from animal
proteins.
14. The composition as is claim 12, wherein said reagent-foam
mixture comprises less than approximately 10 percent by volume of
reagent.
15. The composition as in claim 12, wherein said reagent comprises
carbon dioxide or an inert gas that displaces oxygen.
Description
RELATED APPLICATIONS
[0001] The present application is a Divisional of U.S. patent
application entitled "System and Method for Treating an Excavation
Activity", Ser. No. 13/211,074 filed on Aug. 16, 2011, all of which
is hereby incorporated herein by reference in its entirety for all
purposes. Any disclaimer that may have occurred during prosecution
of the above-referenced application is hereby expressly
rescinded.
FIELD OF THE INVENTION
[0002] The present invention generally involves a composition for
treating an excavation activity. In particular embodiments of the
present invention, the composition may be used to treat byproducts
and conditions associated with excavation activities to reduce acid
rock drainage and/or recover valuable resources.
BACKGROUND OF THE INVENTION
[0003] Byproducts and conditions associated with excavation
activities are known to lead to the generation of various forms of
environmentally harmful pollution. As used herein, excavation
activities encompass not only conventional mining operations to
locate and recover natural resources below the surface of the
earth, but also any other operations that disrupt large areas of
the natural surface and/or contour of land. For example, highway
construction and other large commercial developments often produce
the same byproducts and conditions as conventional mining
operations and constitute excavation activities within the scope of
the present inventions.
[0004] FIG. 1 provides an exemplary drawing of an excavation
activity 10 to illustrate various byproducts and conditions that
may lead to the generation of various forms of environmentally
harmful water pollution. The byproducts may include, for example,
various forms of mineral processing waste, such as overburden 12,
slag, gangue, and buried pyrite-bearing rock 14. The conditions may
include, for example, the excavation site itself, draining adits,
tunnels 16, abandoned pits 18, and mines. As shown in FIG. 1, rain
water 20, runoff 22, and other sources of water may pass over and
through various portions of the excavation activity 10 and interact
and react with the byproducts and conditions to produce undesirable
water pollution 24. The undesirable water pollution 24 generally
gravity drains through the excavation activity 10 until it reaches
an impermeable barrier, such as a natural or man-made liner 26,
which eventually guides the water pollution to an outfall, such as
a stream or underground well or ground water infiltration/recharge
zone.
[0005] The water pollution 24 produced by excavation activities may
be generically referred to as acid rock drainage (ARD) or acid mine
drainage (AMD), and will hereinafter be collectively referred to as
ARD. The combination of water, bacteria, and sulfide minerals
exposed to air by excavation activities produces sulfuric acid,
sulfates, iron and other metals in the ARD. For example, the
following four generally-accepted chemical reactions describe the
oxidation of sulfide minerals (represented by FeS.sub.2 as a proxy
for all reactive sulfide minerals) that produces ARD:
FeS.sub.2+7/2O.sub.2+H.sub.2O.fwdarw.Fe.sup.2++2SO.sub.4.sup.2-+2H.sup.+
1.
Fe.sup.2++1/4O.sub.2+H.sup.+.fwdarw.Fe.sup.3++1/2H.sub.2O 2.
Fe.sup.3++3H.sub.2O.fwdarw.Fe(OH).sub.3+3H.sup.+ 3.
FeS.sub.2+14Fe.sup.3++8H.sub.2O.fwdarw.15Fe.sup.2++2SO.sub.4.sup.2-+16H.-
sup.+ 4.
[0006] As shown by the preceding equations, the elementary chemical
ingredients required for the formation of ARD are air, water, and
sulfide materials. As described below, bacteria can facilitate the
formation of ARD. Once each elementary ingredient is present, the
production of ARD may be predicted by a number of standard tests,
including acid-base accounting tests, humidity cell tests, and
column leach tests. For example, in a pH environment of less than
approximately 4.5, naturally-occurring bacteria, such as
acidithiobacillus ferro-oxidans and related microbes, may act as a
catalyst and accelerate reactions 1, 2, and 4 above, lowering the
pH even further. Hydrogen ions (H.sup.+) and ferric iron ions
(Fe.sup.+3) may also accelerate the oxidation of other metal
sulfides that may be present, releasing additional metals such as
copper, lead, zinc, cadmium, mercury, and manganese into the
ARD.
[0007] An effective method for reducing and/or preventing ARD is to
remove and/or isolate one or more of the elementary
ingredients--air, water, sulfide materials, and/or
bacteria--required for ARD production. For example, a generally
accepted system and method for treating byproducts and conditions
associated with an excavation activity is to disperse one or more
active ingredients or reagents over the excavation site to react
with one or more of the elementary ingredients. As shown in FIG. 1,
however, the byproducts and conditions associated with excavation
activities are often buried, widely dispersed, and otherwise
inaccessible to direct application of the active ingredients,
requiring a combination of closely-spaced boreholes, gravity, and
voluminous amounts of water to transport the active ingredients to
the affected areas to be treated. Although effective at reducing or
preventing ARD for the areas actually reached, the water-dispersed
active ingredients often fail to reach all of the byproducts and
conditions requiring treatment before passing through the
excavation site. Therefore, an improved system and method for
reliably dispersing active ingredients to treat excavation
activities would be useful.
BRIEF DESCRIPTION OF THE INVENTION
[0008] Aspects and advantages of the invention are set forth below
in the following description, or may be obvious from the
description, or may be learned through practice of the
invention.
[0009] One embodiment of the present invention is a composition for
treating an excavation activity that includes a reagent suspended
in foam to form a reagent-foam mixture. The reagent is selected to
react with at least one of sulfides or bacteria in waste rock or
tailings materials to reduce acid rock drainage. The reagent
includes at least one of limestone, dolomite, sodium bicarbonate,
steel slag, fly ash, or sodium hydroxide.
[0010] Another embodiment of the present invention is a composition
for treating an excavation activity that includes a reagent
suspended in foam to form a reagent-foam mixture. The reagent is
selected to react with at least one of sulfides or bacteria in
waste rock or tailings materials to reduce acid rock drainage. The
reagent includes at least one of milk, sodium thiocyanate,
bio-solids, sawdust, paper, or composted animal manure.
[0011] The present invention may also include a composition for
treating an excavation activity that includes a reagent suspended
in foam to form a reagent-foam mixture. The reagent is selected to
react with at least one of sulfides or bacteria in waste rock or
tailings materials to reduce acid rock drainage. The reagent
includes at least one of iron, copper, manganese oxide, zeolite
minerals, peat, activated carbon, or organic resins.
[0012] Those of ordinary skill in the art will better appreciate
the features and aspects of such embodiments, and others, upon
review of the specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] A full and enabling disclosure of the present invention,
including the best mode thereof to one skilled in the art, is set
forth more particularly in the remainder of the specification,
including reference to the accompanying figures, in which:
[0014] FIG. 1 is a simplified cross-section drawing of an exemplary
excavation activity;
[0015] FIG. 2 is a simplified block diagram of a system for
treating an excavation activity according to one embodiment of the
present invention;
[0016] FIG. 3 is a simplified cross-section drawing of the
excavation activity shown in FIG. 1 being treated according to one
embodiment of the present invention;
[0017] FIG. 4 is a simplified cross-section drawing of an
excavation deposit being treated according to an embodiment of the
present invention; and
[0018] FIG. 5 is a simplified cross-section drawing of an
excavation pit being treated according to an embodiment of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Reference will now be made in detail to present embodiments
of the invention, one or more examples of which are illustrated in
the accompanying drawings. The detailed description uses numerical
and letter designations to refer to features in the drawings. Like
or similar designations in the drawings and description have been
used to refer to like or similar parts of the invention.
[0020] Each example is provided by way of explanation of the
invention, not limitation of the invention. In fact, it will be
apparent to those skilled in the art that modifications and
variations can be made in the present invention without departing
from the scope or spirit thereof. For instance, features
illustrated or described as part of one embodiment may be used on
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention covers such modifications and
variations as come within the scope of the appended claims and
their equivalents.
[0021] Various embodiments of the present invention provide a
system and method for transporting and applying various gaseous,
liquid, and/or solid active ingredients or reagents through natural
or man-made porous and permeable media to treat an excavation
activity to reduce and/or prevent water pollution, namely acid rock
drainage (ARD), and/or facilitate valuable resource recovery. A
stable foam slurry may be used to transport and apply the gaseous,
liquid, and/or solid active ingredients or reagents. In particular
embodiments, the system and method may be used at or with an
excavation activity, including zones adjacent to the excavation
activity and/or excavation deposits, to reduce and/or prevent the
spread of ARD. Although described generally in the context of
treating and/or preventing acid rock drainage associated with
mining activities, one of ordinary skill in the art will appreciate
that embodiments of the present invention may be readily adapted to
treat virtually any excavation or mineral processing activity to
reduce and/or prevent the spread of undesirable contamination.
[0022] FIG. 2 provides a simplified block diagram of a system 30
for treating an excavation activity 32 according to one embodiment
of the present invention. As previously described, the excavation
activity 32 may encompass byproducts and conditions associated with
conventional mining operations as well as any other operations that
disrupt large areas of the natural surface and/or contour of land.
The byproducts and conditions may comprise porous and permeable
materials, such as broken or fractured geological rock formations,
ore, ore concentrates, coal, mine tailings, mine waste, slag, sand,
or soil. Metallurgical processes, natural chemical changes such as
oxidation, and/or biological activity may act on the porous and
permeable materials to produce ARD, as previously described.
Alternately, or in addition, the byproducts and conditions may
contain valuable constituents, such as gold, silver, the platinum
group metals, uranium, copper, lead, zinc, or any element that
could economically be recovered from ore either found in place or
excavated from the ground and subjected to conventional
metallurgical processes for economic recovery.
[0023] As shown, the system 30 generally includes a distribution
network 34 in fluid communication with the excavation activity 32.
The distribution network 34 may be proximate to or remote from the
excavation activity 32 and may comprise any suitable system for
conveying or transporting a fluid to the excavation activity 32.
For example, as shown in FIG. 2, the distribution network 34 may
comprise a piping system 36 and one or more pumps 38 or blowers
that provide fluid communication between one or more supply tanks
and the excavation activity 32. The piping system 36 may connect,
for example, one or more of a surfactant tank 40, a liquid reagent
tank 42, a compressor 44, and/or a solid reagent tank 46 to the
excavation activity 32. In this manner, the various tanks may
supply one or more active ingredients or reagents to the excavation
activity 32 to remove and/or isolate one or more of the elementary
ingredients--air, water, sulfide materials, and/or
bacteria--required for ARD production.
[0024] The surfactant tank 40 may supply a foaming agent 48 to the
distribution network 34 to create a stable foam media for
transporting or conveying one or more active ingredients or
reagents to the excavation activity 32. As used herein, "foam"
includes any two-phase fluid comprised of a liquid and a gas
partitioned by a surfactant (e.g., soap) into bubbles. The foaming
agent 48 may comprise, for example, sodium lauryl sulfate, ammonium
lauryl sulfate, sodium laureth sulfate, natural surfactants derived
from animal proteins, and/or combinations thereof. The actual
foaming agent 48 and the active ingredients it carries will be
customized for each application based on the objective of the
application, the chemical makeup, physical condition, and
microbiological suites present, and the degree of saturation of the
polluting or resource-grade materials. It should be understood by
one of ordinary skill in the art that various surfactants are
contemplated within the scope of the present invention, and the
present invention is not limited to any particular surfactant
unless specifically recited in the claims.
[0025] The liquid reagent tank 42, compressor 44, and/or solid
reagent tank 46 may supply one or more active ingredients or
reagents to mix with the foaming agent 48, with the actual active
ingredients or reagents selected to react with one or more of the
elementary ingredients--air, water, sulfide materials, and/or
bacteria--required for ARD production. For example, the liquid
reagent tank 42, if present, may supply one or more liquid active
ingredients or reagents 50 selected to react with one or more of
the elementary ingredients. The liquid reagent tank 42 may supply a
liquid bactericide selected to react with bacteria at the
excavation activity 32 to reduce and/or prevent the production of
ARD. Possible bactericides include, for example, sodium lauryl
sulfate, waste milk or other dairy by-products, bi-polar lipids,
and/or sodium thiocyanate. Alternately or in addition, the liquid
reagent tank 42 may supply solutions, such as sodium hydroxide
and/or hydrated lime solutions, selected to adjust the pH at the
excavation activity 32. In still further embodiments, the liquid
reagent tank 42 may supply solutions, such as sodium cyanide,
thiourea, sodium hypochlorite, and/or hydrogen peroxide, selected
to dissolve or leach precious metals from the excavation activity
32. By way of further example, the liquid reagent tank 42 may
supply solutions selected to coat the excavation activity 32 and
isolate the excavation minerals from air and/or water. For example,
a solution of dissolved potassium permanganate has been shown to
coat particulate mine waste materials with a layer of manganese
dioxide and thus isolate pyrite-bearing rocks from air and water to
prevent the production of ARD. Similarly, solutions of dissolved
phosphate have been shown to complex with dissolved iron and starve
bio-oxidation of pyrite through disruption of the kinetics of
equations 2, 3, and 4 previously discussed.
[0026] The compressor 44, if present, may similarly supply one or
more gaseous active ingredients or reagents 52 selected to react
with one or more of the elementary ingredients. For example, the
compressor 44 may supply carbon dioxide, nitrogen, or other inert
gases that can displace oxygen proximate to the byproducts and
conditions associated with the excavation activity 32, thereby
interfering with or preventing one or more of the chemical
reactions known to produce ARD. Alternately or in addition, the
compressor 44 may supply hydrogen sulfide which, in addition to
displacing oxygen, may also immobilize heavy metals present in
solution at the excavation activity 32.
[0027] The solid reagent tank 46, if present, may similarly supply
one or more solid active ingredients or reagents 54 selected to
react with one or more of the elementary ingredients. For example,
limestone, dolomite, cement kiln dust, steel slag, sodium
bicarbonate, fly ash, and various pozzolanic materials may provide
acid-neutralizing alkalinity to sulfide-bearing rock materials
prone to produce ARD. Alternately, or in addition, slow-release
bactericides may be used to suppress pyrite oxidizing bacteria,
and/or organic materials, such as cellulose, wood, and paper,
bio-solids, and/or animal and vegetable proteins may be used to
suppress pyrite oxidation. Processed peat, natural peat, zeolite
minerals, manganese oxides, and similar man-made products such as
resins may be added to adsorb heavy metals. Additional solid active
ingredients or reagents within the scope of the present invention
may include zero valent iron, nano-scale iron, powdered iron
oxy-hydroxides, and powdered copper which have the ability to
chemically alter or detoxify dissolved pollutants.
[0028] As shown in FIG. 2, the various liquid, gaseous, and/or
solid active ingredients or reagents 50, 52, 54 are mixed or added
to the foaming agent 48 to form a reagent-foam composition or
mixture 56. For example, a foam tube 58 and/or a mixer 60 may be
included in the distribution network 34, as needed, to
homogeneously mix or prepare the reagent-foam mixture 56. The
actual active ingredient or reagent mixed with the foaming agent 48
will depend on the actual conditions at the excavation activity 32.
For example, Table I below identifies various active ingredients or
reagents that may be selected to react with one or more of the
elementary ingredients--air, water, sulfide materials, and/or
bacteria--required for ARD production:
TABLE-US-00001 TABLE I Elementary Ingredient Reagent Anticipated
Reaction Air Fresh or composted wood chips, Consumes oxygen by
sawdust, or cellulose organic decay Mushroom compost Animal &
vegetable protein Bio-solids Paper products Nitrogen Displaces
air/oxygen Carbon Dioxide Hydrogen Sulfide Displaces air &
forms metal sulfides Water Potassium permanganate Coats reactive
solutions surfaces to render Keeco Mix (micro-silicate them
impermeable encapsulation material) Paint (latex or oil-based) or
other water-resistant coating material Sulfides Limestone
Neutralize acidity Dolomite Kiln dust Sodium bicarbonate Fly ash
Flue gas desulfurization Coal combustion by-products Pozzolanic
materials (cement) Steel slag Lime solution Sodium hydroxide
solution Ammonia solution Bacteria Sodium lauryl sulfate solution
Bactericide Sodium lauryl sulfate Milk Bi-polar lipids Phosphate
solution Sodium thiocyanate solution Composted animal manure
Inoculate polluting Municipal sewage bio-solids materials with
beneficial Natural soils from wetlands bacteria Keeco Mix
(micro-silicate encapsulation material)
[0029] Alternately, or in addition, Table II below identifies
various active ingredients or reagents that may be selected to
react with one or more heavy metals or other pollutants to
facilitate recovery, detoxification, and or immobilization:
TABLE-US-00002 TABLE II Pollutant Reagent Anticipated Reaction
Heavy Metals (e.g., Zero Valent Iron Adsorb dissolved Cd, Hg, Pb)
or Nano-scale iron metals to the reagent Base Metals (e.g., Iron
oxy-hydroxide Cu, Zn, Fe) powder Copper powder Manganese oxide
minerals Peat (processed & natural) Zeolite minerals Organic
resins Activated carbon Dissolved and/or Zero Valent Iron Convert
toxic dissolved volatile organic Nano-scale iron organic carbon
compounds compounds to harmless compounds Sodium cyanide Bleach
(sodium Detoxify cyanide leach solutions hypochlorite solution) in
gold mining Hydrogen peroxide solution Sulfur dioxide Sodium
cyanide Sodium cyanide Leach gold or silver leach solution from ore
Buffered carbonate Sodium bicarbonate Leach uranium solution from
ore Thiourea leach H.sub.2NCSNH.sub.2, an Leach gold or silver
solution organic compound from ore soluble in water Sulfuric acid
H.sub.2SO.sub.4 Leach copper or uranium leach solution from ore
[0030] As shown in FIG. 2, the reagent-foam composition or mixture
56 may be dispersed over the excavation activity 32 using standard
grouting technology such as packers, specialized grout casing, or
foam-retaining bulkheads for large underground mine voids, as
desired. At the point of introduction, the reagent-foam mixture 56
expands omni-directionally (upward, downward, and
circumferentially) as an advancing front that coats and saturates
the porous and permeable materials present at the excavation
activity 32. The grout tubing or packers may be repositioned as
needed to allow the injection point(s) to be varied to disperse the
reagent-foam mixture 56 in the desired zone.
[0031] Preliminary tests have shown that the foaming agent 48
effectively penetrates porous and permeable materials commonly
found at excavation activities 32, leaving a coating on the
materials when the foam dissipates. For example, the exothermic
reactions associated with the oxidation of sulfides frequently
results in warm, dry zones that will quickly dissipate the moisture
from the foam, precipitating a higher concentration of active
ingredients or reagents at that particular location that suppress
additional chemical or bacterial oxidation. In addition, the
precipitated active ingredients or reagents do not obstruct or
otherwise clog the porous and permeable materials, allowing for
subsequent applications over time without a loss of effectiveness.
As a result, multiple reagents may be applied in sequence, if
desired, using the same injection point or distribution network 34.
These and other benefits indicate that the foaming agent 48
provides superior transport and deposition characteristics compared
to conventional liquid dispersal techniques, while requiring
substantially less water.
[0032] As further shown in FIG. 2, the system 30 may further
include a liner 62 and/or a collection network 64 in fluid
communication with the excavation activity 32. The liner 62 may
comprise a natural or man-made surface beneath at least a portion
of the excavation activity 32 that provides a barrier for any water
draining from the excavation activity 32. Alternately, or in
addition, the collection network 64 may comprise perforated
drainage pipes that collect and channel water draining from the
excavation activity 32 to a collection point 66 for additional
processing and disposal.
[0033] FIGS. 3-5 provide simplified drawings of various excavation
activities being treated according to embodiments of the present
invention. For example, FIG. 3 shows the use of multiple injection
ports 68 to distribute and disperse the reagent-foam mixture 56
into a buried excavation deposit 70. The omni-directional expansion
of the reagent-foam mixture 56 through the excavation deposit 70
allows for complete coverage of the excavation deposit 70 using
fewer injection ports 68, with a corresponding reduction in water
consumption. As shown in FIG. 4, the omni-directional expansion of
the reagent-foam mixture 56 allows the system 30 to treat a surface
excavation deposit 72 from the bottom. Expansion of the injected
reagent-foam mixture 56 beneath the excavation deposit 72 causes
upward dispersal and distribution of the selected active
ingredients or reagents. Finally, FIG. 5 shows use of the system 30
to economically treat localized or isolated excavation activities
such as fractures 74 or other shallow geological disturbances in an
excavation pit 76. As shown, the distribution network 34 may
facilitate precise application of the reagent-foam mixture 56,
thereby reducing the consumption of water and active ingredients in
the process.
[0034] One of ordinary skill in the art can readily determine with
minimal experimentation preferred combinations and ratios of the
various foaming agents and active ingredients or reagents depending
on the particular excavation activity. Based on the enhanced
distribution and dispersal characteristics of the foaming agent 48
compared to conventional distribution and dispersal methods, it is
anticipated that the fractional percentage of active ingredients or
reagents in the reagent-foam mixture will be substantially less
than needed in conventional methods. For example, it is anticipated
that the active ingredients or reagents, particularly the solid
active ingredients or reagents, will comprise less than 10%, and in
some embodiments less than 5%, 2%, or 1%, by volume of the
reagent-foam mixture, resulting in substantial savings.
Nonetheless, the following hypothetical examples are provided for
illustration and not limitation of the present invention.
Example 1
[0035] An excavation activity comprises a twenty acre excavation
deposit containing a pollution generating pyrite-bearing rock zone
that has been delineated through borehole and geophysical data. The
excavation deposit has a total volume of approximately 3.2 million
cubic yards, of which approximately one-third or 1.1 million cubic
yards is void space. Approximately 25% of the excavation deposit
volume (i.e., approximately 806,000 cubic yards) contains the
pollution generating pyrite-bearing rock, with approximately
266,000 cubic yards of voids in this pollution-generating zone.
[0036] The designed distribution network includes a commercial air
compressor with a capacity of 100 cubic feet per minute and a
standard pressure of 100 pounds per square inch, a pump with a
capacity from 5 to 20 gallons per minute, tanks, and other
conventional foam-generating equipment connected generally as shown
in FIG. 2. The designed piping system includes 4-inch diameter pipe
installed in a plurality of boreholes drilled into the approximate
geometric centroids of the pyrite-bearing rock zones. The annulus
between the pipe and the surrounding pyrite-bearing rock zones is
filled with sand or concrete.
[0037] The active ingredients or reagents for this application are
selected to provide an anti-bacterial action, acidic pH
neutralizing actions, and oxygen depletion actions. The selected
anti-bacterial reagents include sodium lauryl sulfate (which is
also the foaming agent); waste milk (nutrient for beneficial
bacteria to out-compete pyrite-oxidizing bacteria); and bio-solids
(bacterial inoculum). The selected acidic pH neutralizing reagent
is finely crushed limestone powder having a grain size from
approximately 20 mesh (0.84 mm) to approximately 200 mesh (0.074
mm). The selected oxygen-depleting reagent is a fine-grained
sawdust waste product having a nominal diameter of approximately 20
mesh (0.84 mm). Hypothetical laboratory testing and/or field trials
indicate the following ratios of the foaming agent and active
ingredients or reagents produce the desired reagent-foam
mixture:
TABLE-US-00003 Volume in 1 cubic Component yard of mixture Percent
by Volume Water 3.20 cubic feet 11.9% Waste milk 0.17 cubic feet
0.6% Bio-solids 0.15 cubic feet 0.6% Crushed limestone 0.80 cubic
feet 3.0% Sawdust 0.05 cubic feet 0.2% Surfactant (SLS) 0.21 cubic
feet 0.8% Gas (air) 22.42 cubic feet 83.0% Totals 27.0 cubic feet
100%
[0038] The resulting reagent-foam mixture contains about 3.85%
solids by volume or about 10,238 cubic yards of solid active
ingredients for the entire treatment outlined in this example.
Example No. 2
[0039] An excavation activity comprises a 200 acre abandoned open
pit mine site that exposes a fractured, pyrite-bearing rock zone
that has been delineated through borehole, geochemical data, and
geologic interpretation. The fracture zone is a combination of
natural geological conditions and over-break from blasting activity
in creating the excavation. The zone of intense fracturing extends
at least 100 feet into the excavation wall rock and through the
floor of each bench, as shown in FIG. 5. The fractures constitute
less than 1% of the total rock mass volume. Every linear foot of
excavation bench includes an estimated 150 cubic yards of rock, of
which 1.5 cubic yards are void space. There are 2 miles of bench in
the pyrite-rock exposure, resulting in 15,840 cubic yards of
fracture that requires treatment in this pollution-generating
zone.
[0040] The designed distribution network includes a commercial air
compressor with a capacity of 100 cubic feet per minute and a
standard pressure of 100 pounds per square inch, a pump with a
capacity from 5 to 20 gallons per minute, tanks, and other
conventional foam-generating equipment connected generally as shown
in FIG. 2. The designed piping system includes 2-inch diameter pipe
installed in a plurality of boreholes drilled into the
pyrite-bearing fractured rock zones. The annulus between the pipe
and the surrounding pyrite-bearing rock zones is filled with
cementitious grout to seal the pipe into the rock mass.
[0041] The active ingredients or reagents for this application are
selected to provide an anti-bacterial action and acidic pH
neutralizing actions. The anti-bacterial ingredients include sodium
lauryl sulfate (which is also the foaming agent); waste milk
(nutrient for beneficial bacteria to out-compete the pyrite
oxidizing bacteria); and bio-solids (bacterial inoculum). The
selected acidic pH neutralizing reagent is finely crushed limestone
powder having a grain size from approximately 200 mesh (0.074 mm)
to approximately 400 mesh (0.037 mm) and a solution of sodium
hydroxide having a pH of 12.0. This reagent-foam mixture was
selected to allow the placement of particulate limestone in larger
fractures and the injection of liquid active ingredients in zones
of small fractures. The sodium hydroxide provides immediate pH
reduction, and the limestone provides long-term pH control.
Hypothetical laboratory testing and/or field trials indicate the
following ratios of the foaming agent and active ingredients or
reagents produce the desired reagent-foam mixture:
TABLE-US-00004 Volume in 1 cubic Component yard of mixture Percent
by Volume Water 2.53 cubic feet 9.4% Waste milk 0.84 cubic feet
3.1% Bio-solids 0.0125 cubic feet 0.05% Crushed limestone 0.24
cubic feet 0.9% Sodium Hydroxide 0.0125 cubic feet 0.05% Surfactant
(SLS) 0.21 cubic feet 0.8% Gas (air) 23.17 cubic feet 85.8% Totals
27.0 cubic feet 100%
[0042] The resulting reagent-foam mixture contains about 0.93%
solids by volume or about 3,640 cubic yards of solid active
ingredients for the entire treatment outlined in this example.
[0043] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other and examples are intended to be within the
scope of the claims if they include structural elements that do not
differ from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *