Note: Descriptions are shown in the official language in which they were submitted.
CA 02876770 2016-08-10
Description CA
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TITLE OF THE INVENTION:
Improved Oil Sand Mining and Haulage Method
=
TECHNICAL FIELD OF THE INVENTION:
The technical field of this invention patent disclosure is the science of Bulk
Materials Handling (BMH),
corresponding to the engineering discipline responsible for planning,
designing and implementing
methods and equipment for the excavation of materials from an open pit mine,
crushing these materials
as may be required, transporting these materials by suitable means, providing
for temporary surge
storage capacity in bins or other containment means and reclaiming these
materials for subsequent
handling or processing steps. The invention claimed is a process method having
better performance,
reduced costs, reduced greenhouse gas emissions and resulting in an improved
process flowsheet over
the prior art.
The physical field of the described and claimed invention is in the mining and
materials handling of oil
sand from the mineable oil sand deposits of northern Alberta, Canada. This
invention called "Improved
Oil Sand Mining and Haulage Method" refers to an improved process flowsheet
method of open pit
mining and handling of naturally occurring earth materials containing bitumen-
bearing sand, barren
rock, clays and organic materials commonly known in the industry as oil sand.
Process steps occurring in and beyond the slurry preparation plant (SPP) are
beyond the scope of this
invention disclosure.
BACKGROUND OF THE INVENTION:
Conventional oil sand industry practice for the mining and transportation of
dry oil sand materials uses
the truck and shovel mining and ore transportation method, mining taking place
at multiple faces on
multiple mining benches typically using large mobile electric/hydraulic shovel
excavators and a fleet of
large mine haulage trucks typically travelling variable distances from 1 to 15
km to reach a fixed facility
referred to as a remote "Oil Sand Receiving and Slurry Preparation Plant".
The conventional Oil Sand Receiving and Slurry Preparation Plant typically
features 2 equipment trains
of series-connected equipment comprising 2 receiving truck dump hoppers, 2
reclaiming apron feeder
conveyors, 2 large primary crushers, 2 long inclined surge bin feed belt
conveyors, 2 large surge storage
bins, an additional 2 reclaiming apron feeder conveyors, an additional 2 long
inclined SPP feed
conveyors, 2 slurry preparation plants defining 2 independent trains and 2
slurry pumping/pipeline
systems feeding a remote Extraction plant. Dry oil sand feed to the 2 train
slurry preparation plants
typically falls into the range of 12,000 to 14,000 tonnes of as-mined oil sand
per hour. The industry also
employs single or triple train configurations with appropriate adjustments to
the quantities of
equipment, but using the same sequence of equipment used per process train.
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Although the conventional process flowsheet suffers from a number of systemic
problems including high
initial cost, large in-pit footprint, unreliability of the series-connected
equipment trains, non-
relocatability of the fixed facilities, is a major contributor to greenhouse
gas emissions and typically has
poor availability and productivity, it continues to represent the generic
industry-wide conventional
process flowsheet without having changed significantly over the last three
decades.
Strong advantages to the use of mine haulage trucks are found in their
flexibility in enabling selective
mining from multiple mining faces on multiple mining benches at different
elevations, such mining faces
potentially relatively remote from each other. Ore grade blending is an
important function that can be
satisfied when delivering and combining oil sand feeds from these remote
mining faces typically having
variable ore qualities, to the remote downstream processing facilities. The
productivity of the mobile
excavators and mine haulage trucks is high considering the redundancy options
within typical fleets of 4
mobile excavators feeding a shared fleet of 25 to 35 mine haulage truck units
for every 2 equipment
trains. Oil sand operators favour mine haulage trucks for oil sand
transportation, but admit that the
technology becomes inefficient for haulage distances greater than 5 km,
including excessive production
of greenhouse gases (GHG) from the diesel fuel burning engines.
Availability and productivity issues with conventional technology begin after
the mine haulage trucks
dump their loads of run-of-mine (ROM) oil sand into the truck dump hopper.
From this point onwards
the process flowsheet comprises series-connected process steps of reclaiming
ROM oil sand from the
truck dump hopper using.an apron feeder to feed the large stationary primary
crusher; crushing the
ROM oil sand; using a large belt conveyor to carry, elevate and discharge
primary crushed oil sand into a
large surge bin; reclaiming primary crushed oil sand from the surge bin using
an apron feeder;
discharging reclaimed primary crushed oil sand onto a second large belt
conveyor to carry, elevate and
discharge it into the SPP. Numerous reliability issues are associated with
this part of the process
flowsheet handling dry, abrasive, lumpy oil sand at high tonnage throughput
rates prior to feeding the
SPP.
Operating issues including high labour costs and GHG emissions have been
identified and targeted by
several recent patents, featuring the use of conveyor systems to replace the
mine haulage truck fleets,
some examples being Syncrude CA 2642557 and CA 2643292 and Canadian Oil Sand
CA 2480122, CA
2453697, US 7,431,830 and Suncor Energy CA 2567644 and WO 2010037215 Al. It is
well known in the
industry and acknowledged in the patents of MacDougal in CA 2567644 and
Cymerman in CA 2029795
that issues of high cost and maintenance downtime are associated with
conveyors operating in oil sand.
These patents proposing to use long series-connected equipment trains of
conveyors and other
processing equipment steps therefore raise questions of inherently poor
reliability and productivity of
these long equipment trains. Also important is their inherent lack of mining
flexibility for selective
mining and ore grade blending. None of these recently patented conveyor-based
haulage technologies
have been implemented .as primary production trains by the industry.
Three examples of slurry-at-face systems were proposed in Syncrude CA 2567644
and MMD Design 8c
Consultancy CA 2558059 and CA 2498862. Full scale pilot trials done for slurry-
at-face systems have not
been successful, largely due to the lack of satisfactory bitumen recovery and
the requirement to provide
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extensive extendable infrastructure to operate slurry preparation facilities
in-pit. Slurry-at-face systems
still represent high risk unproven technology in the oil sand industry.
During development of the Improved Oil Sand Mining and Materials Handling
Method, the primary
competing prior art was therefore concluded to be conventional industry
practice, since none of the
recent art featuring extensive use of conveyors or slurry-at-face systems has
been adopted by the oil
sand industry for more than laboratory or pilot trials due to the multiple
disadvantages noted above.
NEED FOR NEW TECHNOLOGY:
Procurement practices among owners of "mineable oil sand" leases have
typically reserved all aspects
of mine planning, mine development and mining fleet procurement to be handled
internally, using
specialized niche 3rd party mining consultant firms to assist in open pit
mining and tailings layouts,
geology, reserves calculations, pit layouts for stripping, mining, tailings
and water management. Process
plant design and engineering services on the other hand are typically awarded
to relatively larger 3rd
party Engineering/Procurement/Construction (EPC) contractors having access to
large teams of
traditional multidisciplinary engineering resources, generally led by the
Process Engineering discipline.
There may be more than one EPC Engineering firm chosen for the downstream
facilities, infrastructure
and utilities due to different perceived skill sets and financial capacities
of the relative firms.
Although the mine owner has oversight of all 3rd party engineering resources,
the selected EPC
Engineers have little insight or input on the mining side of these large scale
projects. A "Battery Limit"
separating the "mine" from the "plant" scopes of work is usually defined at
the entrance to the "truck
dump hopper", where the mine haulage trucks dump as-mined oil sand into a
fixed hopper feeding the
large fixed primary crusher. Due to this somewhat arbitrary scope separation,
technology innovation for
dry oil sand mining and handling has stagnated. In fact, the essence of this
patent disclosure could have
been proposed at any time over the last 30 years.
This present invention disclosure recognizes that "bulk materials handling"
spans both sides of the
traditional contractual "battery limit" at the truck dump hopper. The
inventive concepts of this
disclosure arise out of considering an expanded scope to include all "dry
materials handling" from the
mining faces to the entrance of the slurry preparation plant with no
recognition of the prior restrictive
battery limit. The advantages and benefits described in this disclosure were
obtained through this
revised approach.
SUMMARY OF THE INVENTION:
Therefore, the scope of this patent disclosure begins at the mining face and
ends at the entrance to the
slurry preparation plant, reflecting an expanded EPC project scope including
all of the dry oil sand
mining and materials handling steps from the mining faces to the SPP. It is a
method patent which
discloses an improved process flowsheet method in comparison to the industry's
conventional process
flowsheet, the improved method based upon fundamental scientific principles of
the engineering
discipline called Bulk Materials Handling (BMH). It addresses existing
problems with conventional
industry practise and also the expected deficiencies of more recently patented
prior art, proposing to
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significantly improve system availability and productivity, also to achieve
lower initial costs, lower on-
going operating costs and higher revenues due to improved productivity. The
improved method also
offers multiple options to reduce greenhouse gas (GHG) emissions, resulting
from a reduction of
installed horsepower and, more effective options to manage truck haulage
distances.
The patent disclosure focuses on four fundamental scientific principles for
BMH:
= De-couple series-connected process equipment trains;
= Introduce process-step redundancies;
= More effective surge storage capacity utilization and
= Simplification of the overall process flowsheet.
In this patent disclosure "de-coupling" is defined as the breaking of series-
connected one-on-one
processing train equipment relationships and "redundancy" refers to multiple
units of identical or
alternative technology equipment operating simultaneously in parallel
independent relationships but
performing the same process function with an incrementally cumulative effect.
De-coupling and
provision of multiple redundancies will achieve increased availability and
productivity of the mining and
materials handling system because the failure or stoppage of any single
production equipment unit will
not stop or even greatly influence the continued operation of the overall
system production functions.
The phrase "multiple unit redundancies" in which many or all of the redundant
units are intended to
operate simultaneously in parallel is fundamentally different from an
alternate meaning of the word
"redundant", in which a single-step processing unit may have a parallel,
single-step redundant process
unit installed beside it, only one of which is intended to operate at any one
time. In the following
description it will be clear that the improved method of this patent relies
upon "multiple" rather than
"single" units of redundantly parallel operating equipment at each step of the
improved process
flowsheet.
The Description and Claims of this patent disclosure are presented in the
context of a mine equipment
fleet comprising; 4 mobile excavators at 4 mining faces cooperatively paired
with 4 mobile primary
crushers loading primary crushed oil sand into a shared fleet of 25 to 35 mine
haulage trucks, supplying
2 remote surge bins (SB) with 2 slurry preparation plants (SPP) and having 2
hydrotransport (HT) oil sand
slurry pumping and pipeline equipment trains, for a total oil sand demand rate
in the range of 12,000 to
14,000 tonnes per hour to operate both trains simultaneously.
The term Availability can be defined mathematically as the time that a unit of
equipment is available to
operate divided by the time it is scheduled to operate. Any equipment unit
stoppage due to
unscheduled delays or maintenance issues will reduce its "available" time,
hence its availability and
productivity.
In a system of multiple series-connected equipment units comprising a pair of
independent oil sand
process equipment trains, every unit of equipment has characteristic failure
rates and time durations of
failure, usually expressed in statistical or probability math and failure
distribution bell curves. The
mathematical availability of a complete series-connected equipment train can
be calculated using a
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computer modelling tool; in which the measured individual equipment
availabilities are statistically
aggregated to arrive at a characteristic system availability value. Poor
availability of a mining and
materials handling system has serious impacts, since lost production tonnes
are the result and
downstream process upsets m ay occur if the stoppage duration is more than a
few minutes.
In simple terms, the learnings derived from conducting such analyses
demonstrate that adding more
units of equipment into a series-connected equipment train will reduce system
availability, but deleting
units of equipment from the train will increase system availability.
Similarly, de-coupling of series-
connected equipment trains will enable the addition of redundant equipment
units which together can
greatly increase system availability. Adding effective surge capacity at
appropriate locations in a process
flowsheet containing batch and continuous sequential processes also increases
system availability.
Improved system availability of an oil sand mining and materials handling
system will directly increase
productivity leading to cost reductions and increased revenue generation.
De-coupling of series-connected equipment trains in this improved patent
method is enabled firstly by
the key method step of relocating the primary crusher to the mining face in a
mobile configuration. In
the improved method each mobile excavator at each mining face will be paired
with a cooperating
mobile primary crusher, which will then discharge primary crushed oil sand to
the shared fleet of 25 to
35 mine haulage trucks, each mine haulage truck transporting primary crushed
oil sand to the remote SB
and SPP equipment trains (meaning 2 oil sand surge storage and slurry
preparation equipment trains).
An availability calculation for the ore preparation facility will no longer
need to include failure rates of
the large fixed primary crusher, its apron feeder conveyor or its heavy duty
inclined SB feed conveyor,
firstly because this equipment is no longer located at the fixed distal Oil
Sand Receiving and Slurry
Preparation Plant, and secondly because the intervening trucking function
effectively de-couples
equipment located at the mining face from equipment located at the distal Oil
Sand Receiving and Slurry
Preparation facilities.
Providing significant surge capacity in the receiving and storage hopper of
the mobile primary crusher
also has a de-coupling effect between the mobile excavator, the mobile primary
crusher and the mine
haulage truck fleet, somewhat isolating the operation of the mobile excavator
from the irregular arrival
and spotting of the mine haulage trucks, resulting in improved productivity of
both the mobile excavator
and the mine haulage trucks. "Providing significant surge capacity" in this
disclosure may represent
about 2 bucket loads of oil sand from the mining excavator, enabling the
mobile excavator to pre-load
the mobile crusher's receiving and storage hopper even before a haulage truck
arrives and to add one or
more additional bucket loads into the mobile crusher's receiving and storage
hopper during operation
of the mobile crusher and filling of the mine haulage truck, and to continue
loading into the mobile
crusher's receiving and storage hopper after the loaded mine haulage truck
departs.
In the improved patent method each process step of excavating, crushing,
haulage and SB storage is de-
coupled from its preceding and/or succeeding process steps, thus enabling the
introduction of multiple
unit redundancies for each process step of equipment used.
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For the improved method, increased Redundancy benefits will appear first at
the 4 mobile primary
crushers paired with 4 mobile excavators, which is double the conventional
practice of having only 2
large fixed primary crushers series-connected with the rest of 2 independent
equipment trains of the
distal Oil Sand Receiving and Slurry Preparation Facilities. Should any single
pair of mobile
excavators/mobile crushers be taken out of service in the improved method, the
remaining 3 mobile
excavator/mobile crusher pairs will be able to make up for the lost oil sand
production tonnage per
hour, the mine haulage truck fleet will be redistributed to haul from 3
operating mining faces instead of
4. Similarly, redundancy carries over to the mine haulage trucks; if any mine
haulage truck fails or is
being serviced, the balance of the typical shared 25 to 35 mine haulage truck
fleet can make up for the
lost production of one or more mine haulage trucks taken out of service.
An unexpected Increase in Surge capacity of prepared oil sand results from the
de-coupling and
redundancies noted above. In this improved method the mine haulage trucks have
gained an additional
new function of carrying the same primary crushed oil sand as is held in the
SB, therefore incrementing
the tonnage of prepared primary crushed oil sand available to be fed to the
SPP without adding
additional equipment to the flowsheet. The mechanism of this increase is
realized by the repetitive
arrival of mine haulage trucks delivering dynamic live loads of up to 363
tonnes (CAT 797B) of primary
crushed oil sand per load at an average frequency of about once every 1.5
minutes, or 14,520 tonnes
per hour. This functionality creates a new capital cost saving opportunity to
downsize the typical SB
capacity due to this new and unexpected cumulative dynamic live loading of
additional primary crushed
oil sand tonnes being carried by the fleet of mine haulage trucks in transit
to the SB.
The Placement and sizing of the main SB in the flowsheet is critically
important to the successful
continuous operation of the immediately downstream slurry preparation plant
(SPP), hydrotransport
(HT), Extraction and Froth Treatment process steps to avoid process upset
conditions potentially
affecting product recovery, quality, or even causing plant shutdowns.
Each upstream equipment process step in the improved method has its own unique
characteristic set of
possible delays and stoppages, many of which may be of relatively short
duration which can be buffered
by use of a SB of appropriate capacity positioned to feed the SPP directly.
These delays include frequent
re-positioning movements of the mining excavator and mobile crusher, spotting
delays as haulage trucks
arrive empty and depart full, metal rejection procedure delays while loading
haulage trucks, sticky and
frozen ore lump blockages in the crusher feed hopper and crusher, flow rate
surges as the haulage
trucks dump into the SB, routine servicing delays, refueling delays,
electrical fault delays,
instrumentation fault delays, safety stoppages, haulage road maintenance;
human factor delays relating
to lunch and shift changes, training, accidents, severe weather stoppages,
etc. There are also potential
delays of much longer duration to cover major maintenance jobs for which a
calculated minimum
required SB capacity would be considered too large and impractical to
construct and operate. For this
reason SB sizing for conventional technology is typically selected to cover
only short duration stoppages,
in which the cause of the upstream stoppage is likely to be corrected in 20
minutes or less, SB sizing
therefore typically designed to hold 1/2 hour of feed capacity.
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Although the proposed SB sizing procedure outlined in this disclosure is
applicable for all oil sand mining
and handling methods, there is a fundamental difference in the improved art
disclosed herein. The
operation of series-connected equipment trains will stop completely if any
single one of the equipment
units in the series-connected train fails, and the train cannot re-start until
the failed unit is repaired.
Following any unplanned stoppage of the train, the continued operation of the
downstream processes
starting with the SPP would then only be able to continue running until the SB
empties of its contained
live primary crushed oil sand; typically containing only enough feed for about
'/2 hr of continued
operation of the SPP/HT/Extraction train.
The improved art of this disclosure featuring de-coupling and redundancies for
each step of the
sequential process will re'act very differently to failure of a single unit of
production equipment. As an
example, if a mine haulage truck fails or is taken out of service, the
potential haulage capacity of the
total mine haulage truck fleet will be reduced by 1/35th of its nominal
maximum output ¨the impact of
this failure will hardly affect SB or SPP operation considering the excess
sprint haulage capacity available
from the balance of the haulage fleet. The impact of a single pair of the four
mobile excavators/mobile
primary crushers failing or being taken out of service would be much higher at
25% of the total potential
mining and crushing output, but may still be within the excess sprint capacity
of the remaining 3 mobile
excavator/mobile crusher pairs. In both of these examples the tonnage rate
reduction delivered to the
SB may thus be minor, and may still enable the SPP/HT/Extraction plant trains
to continue operation
even at somewhat reduced throughput rates, still within their design turn-down
ratios. This presumed
excess sprint capacity will most likely already have been provided by the mine
operator, as essential for
enabling individual units of excavating, crushing or haulage equipment to be
taken out of service for
routine planned maintenance purposes.
The SB will still be required in the improved flowsheet of the Improved Oil
Sand Mining and Haulage
Method, but its calculated minimum design capacity can likely be much reduced
because of the
expected high availability of the preceding process steps, each featuring de-
coupling and redundancies,
therefore the surge bin can be made significantly smaller and therefore less
costly to construct.
The downstream processes following the SB must preferably operate under
continuous steady state
conditions of HT pumping with a constant mass flow rate, constant and correct
slurry density, known
maximum lump size and constant flow velocity to prevent large lumps in the
pipeline from "sanding out"
and plugging the line. In winter there would be a consequent risk of freezing
the pipeline solid if the
flow was interrupted for an extended time period; even so, the re-starting of
a stopped HT pipeline still
containing HT solids can be problematic. These required operating criteria
cannot be achieved if the
upstream mining and materials handling system can only provide an inconsistent
supply of oil sand, but
can be achieved if the SB.is of sufficient capacity and availability and is
maintained at a high percentage
level of fill to buffer and isolate the upstream batch and downstream
continuous processes from each
other.
Prior art as found in CA 2567644 (May 2007) and CA 2029795 (May 1991) is
particularly deficient in
omitting effective surge capacity from their flowsheets, essentially rendering
these patents as
unworkable and having no utility as presented. As discussed herein under the
descriptive comments for
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Figure 3, the application of BMH science with respect to sizing an appropriate
SB capacity is best
achieved by characterizing the probability distribution of all types of
possible delays for each unit of
upstream equipment, then to aggregate an overall probability distribution
characterizing the total
upstream system. From these calculations an appropriate SB size can be
selected to eliminate a large
percentage of typical short term delay events. From industry experience the SB
usually is sized to
contain at least half of the flow rate capacity of the train, equating to
about 1/2 hour of continued train
operability following a cessation of new feed delivered into the SB.
The Improved Oil Sand Mining and Haulage Method offers an opportunity to
reduce the '/2 hour sizing
criteria, due to the dynamic live surge capacity of loaded mine haulage trucks
constantly delivering loads
of primary crushed oil sand to replenish the SB at a predictable average
frequency and load capacity.
The process flowsheet can be improved for the haulage and SB functions by
relocating the SB into a slot
in the mechanically stabilized earth (MSE) wall in the former location of the
fixed truck dump hopper,
apron feeder and large fixed primary crusher. Mine haulage trucks will then be
enabled to direct-dump
primary crushed oil sand into the SB, the trucks accessing the dumping
positions by approaching the SB
on top of the MSE wall. This new structural configuration will eliminate 2
expensive heavy duty inclined
conveyors feeding the SB; one for each train.
Similarly, additional process flowsheet simplification can be achieved by co-
locating the SB and the SPP
facilities in close proximity to each other, directly connected using the SB
apron feeder reclaiming and
discharge conveyors to feed the 2-train SPP. This new structural configuration
will eliminate an
additional 2 expensive heavy duty inclined conveyors feeding the SPP; one for
each train. This latter
apparatus configuration is not claimed herein as it is already shown in prior
art by Canadian Oil Sand CA
2480122, but it is claimed as part of this Improved Oil Sand Mining and
Materials Handling Method
offering an improved process flowsheet.
In the improved method there will be GHG emissions savings opportunities
associated with the
elimination of up to 12,000 installed horsepower for the 4 heavy duty inclined
conveyors removed from
the improved process flow sheet. The reduced structural equipment layout of
the SB and SPP facilities
may require only a tenth of the footprint of today's conventional art, thus
reducing the cost and GHG
impact of the construction functions required for site preparation and
maintenance. An important
corollary to the reduced construction effort is that it will become much more
practical and cost effective
to relocate the receiving and slurry preparation facilities closer to the
mining faces from time to time,
preventing the mine haulage truck distances from becoming longer than about 5
km, thus gaining net
reductions in both operating costs and life-of-mine GHG emissions.
The cumulative benefits of de-coupling, multiple redundancies, improved surge
capacity and improved
process flowsheet achieved by this Improved Oil Sand Mining and Haulage Method
will provide
significant gains in cost savings and system availability, translating
directly into higher production
revenues with reduced maintenance and operating costs, along with reduced GHG
emissions.
Tramp metal detection and removal is not new art, as specific structural means
were shown and claimed
previously in Syncrude CA 2643292, CA 2642557 and Suncor CA 2567644. The oil
sand industry has
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struggled, however, to provide a practical and cost effective detection and
removal method for tramp
metal on conveyors, experiencing too many nuisance trips in large part because
the belts are typically
heavily loaded with oil sand at up to 14,000 tonnes per hour and typically
travel at high speeds of 5 to 6
meters per second. In contrast, the oil sand discharge rate from each of the
new mobile primary
crushers can be much lower at 5,000 to 6,000 tonnes per hour and can be
conveyed into the mine
haulage trucks at a reduced belt speed.
The improved tramp metal removal procedure of this patent disclosure requires
first that an adjustable
sensitivity metal detector be installed on the mobile crusher's discharge
conveyor belt enabling the
sensor to differentiate between heavy tramp metal such as a shovel tooth or
adapter-holder versus
lighter and smaller metal which the downstream process can tolerate. The
sensor will activate an alarm
if heavy tramp metal is detected, initiating a manual or automated removal
procedure as follows:
1. Stop the crusher's feed conveyor, the crusher and the discharge
conveyor;
2. Slew the discharge conveyor sideways away from the mine haulage truck
being loaded;
3. Discharge the large tramp metal directly onto the ground;
4. Slew the discharge conveyor back into its mine truck loading position;
5. Re-start the reclaiming, crushing and truck loading operations.
This improved sensing and removal procedure for large tramp metal avoids
adding extra equipment to
the flowsheet, unlike the.Syncrude prior art patents which requires adding
chutework and a short
reversible conveyor, multiple sensors and a control system to enable
discharging the tramp metal onto
the ground.
An Overland (0/L) Conveyor can also be used in the Improved Oil Sand Mining
and Haulage Method in
such a case that truck haulage distances longer than about 5 km cannot be
otherwise avoided. Although
0/L conveyors are not new art, they can be specified and implemented as unique
steps in the improved
process flowsheet method following the truck haulage step, the overland
conveyor configured to feed
the SB directly. Structural and control means are claimed herein allowing mine
haulage trucks to feed
the overland conveyor at.multiple 0/L conveyor belt loader positions along its
length, and for the SB to
be fed simultaneously from the overland conveyor and directly from mine
haulage trucks. A first
controller is claimed for loading the belts without overloading and spillage
and a second controller is
claimed to achieve and maintain filling of the remote SB.
Prerequisites for using this 0/L conveyor transportation link technology are
satisfied firstly by the mobile
primary crusher's action to reduce oil sand lump size to conveyable
proportions. Particularly in winter
frozen oil sand lumps can be as large as a 3m cube, but the mobile primary
crusher will reduce that to a
typical 350 to 400mm passing screen size. Secondly, the sensing and removal
means and procedure
enables discarding large tramp metal on the discharging conveyance. In
combination these two actions
will prepare the oil sand for 0/L conveyor transportation and processing at
downstream oil sand slurry
preparation facilities. Large tramp metal can otherwise cause conveyor belting
damage and/or plug,
damage or stall downstream process equipment.
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A characteristic of an overland conveyor link or links is that they can be
installed in a fixed location at
any convenient length or direction from the remote SB to suit the mining plan
and the locations of
multiple mining faces, the existing or planned mine truck haulage roads or
other mining pit construction
features including berms or dykes or drainage ditches or ponds in the open pit
mine; the overland
conveyor having a design capability to accommodate both vertical and
horizontal curves; the maximum
design length of the overland conveyor can be constructed either by
incremental extensions over time
or immediately at full design length as required to suit the mining
operations.
An overland conveyor of 4 km length, for example, will have fewer operational
issues than multiple
shorter conveyors making up a similar distance when considering the problems
of handling sticky oil
sand which tend to build-up on the belting and the pulleys. The 0/L conveyor
will have fewer
transfer/loading points where damage and spillage can occur, fewer numbers of
large pulleys per
kilometer and greater spacing of carrying idlers when designed using the new
CEMA 7 design guidelines
(Conveyor Equipment Manufacturers Association design specification manual).
Unique differentiators and benefits for use of a the overland conveyor link
include maintaining the
flexibility of truck haulage from the mining faces, the potential economies of
conveyor transportation
over the mine haulage trucks over long distances, a potentially reduced
frequency of necessary SB/SPP
relocations and potential reductions in GHG emissions by managing the truck
haulage distances.
Summary Comparison of Competing Oil Sand Mining and Haulage Methods
Conventional oil sand industry practice already features de-coupling and
redundancy for the mining and
haulage functions, using 4 mobile excavators at 4 mining faces feeding a
shared fleet of 25 to 35 mine
haulage trucks which transport and dump ROM oil sand ore into remote fixed
truck dump hoppers.
However, the oil sand receiving and slurry preparation equipment trains
comprising the truck dump
hopper, the apron feeder to the large fixed primary crusher, the primary
crusher, the inclined SB feed
conveyor, the SB, the SB discharge apron feeder conveyor and the inclined SPP
feed conveyor in total
represent multiple series-connected equipment units with no possibility for de-
coupling or adding
redundancy to any of the equipment process-step functions within the train,
leading to low system
availability as experienced in industry practice today. Ore grade blending and
selective mining
capabilities are achieved but GHG emissions reduction opportunities are
limited. System relocatability
typically requires a major construction effort of lengthy duration due to the
requirement for multiple
fixed heavy equipment and building structures requiring piecemeal disassembly
and reassembly, also
requiring heavy concrete foundations and construction of new foundations and
facilities in the new
location. There are no further opportunities for de-coupling or redundancy
mitigations to improve the
ore preparation and handling system's availability in conventional industry
practise.
Newly patented art for mining and haulage featuring extensive use of series-
connected conveyors
and/or at-face slurry preparation offers no possibility for de-coupling or
redundancy of any equipment
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units of the series-connected equipment trains beginning at the mining face
through to the slurry
preparation step, unless provided with relatively large surge capacity at one
or more appropriate
locations in the series-connected equipment trains. Notably, the number of
active series-connected
equipment units is potentially much greater in this proposed new art than in
conventional industry
practice, leading to the expectation of even lower train availability than
conventional practice.
Equipment trains of this design would also require continuous mining bench
preparation and frequent
equipment and infrastructure relocations by a large and well equipped pit
construction crew to enable
usage of the mobile or relocatable conveyors. Equipment trains of this design
will be incapable of
selective mining or ore grade blending or of supplying a steady supply of
12,000 to 14,000 tonnes per
hour nominal productive capacity required to feed the slurry preparation
facilities, short of constructing
4 identical mining, primary crushing and conveyor equipment trains operating
continuously in parallel to
feed primary crushed oil sand to the SPP plants, each train independent of
each other and occupying a
large in-pit footprint. The required amount of pit floor preparation and
maintenance and extensions to
relocatable infrastructure would be particularly arduous under typical harsh
winter ambient
temperatures and snow falls.
The Improved Oil Sand Mining and Haulage Method: The preferred embodiment of
this improved
mining and haulage technology is designed to incorporate de-coupling and
redundancy for every
process-step function and provides unique additional surge capacity sources
beginning at the mining
face through to the slurry preparation step. The only active powered equipment
required to feed oil
sand to the SPP without having an opportunity to provide redundancy will be
the single apron feeder
conveyor per train reclairiiing primary crushed oil sand from the SB and
discharging it to the SPP.
Selective mining and grade blending capabilities will be preserved. System
relocatability will be much
simpler and more cost effective than conventional or new art practices and the
footprint of the
SB/SPP/HT facilities will be much more compact. GHG emissions reduction
opportunities will be
available. Production output will be higher than conventional or new art
practices due to the
achievement of high system availability.
Brief Description Of The Drawings:
Figure 1 illustrates a mobile excavator positioned to dump run-of-mine (ROM)
oil sand into a receiving
and storage hopper of a mobile primary crusher, a primary crusher, a metal
detection and discard
system for large tramp metal and a luffable and slewable discharge conveyor;
Figure 2 illustrates a remote SB located in a mechanically stabilized earth
(MSE) wall, feeding primary
crushed oil sand into the feed chute of a closely adjacent Oil Sand Slurry
Preparation Plant;
Figure 3 illustrates the discharging of primary crushed oil sand into the feed
chute of an Oil Sand Slurry
Preparation Plant;
Figure 4 illustrates a block flow diagram of the scope of the preferred
embodiments of the patent
disclosure comprising the mobile excavator, the mobile primary crusher, the
mine haulage truck, the
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remote SB and the oil sat-id slurry preparation plant. Also included is an
Overland Conveyor capable of
transporting primary crushed oil sand to the remote SB;
Figure 5 illustrates an alternate embodiment of the patent disclosure
including the Overland Conveyor,
the OIL conveyor belt loader, the remote SB and 2 controllers controlling the
operation of each of the
OA conveyor belt loader and the remote SB filling.
Detailed Description:
The scope of the preferred embodiment of the Improved Oil Sand Mining and
Haulage Method for
which patent protection is requested begins at multiple oil sand mining faces
such as are typical of the
mineable oil sand of Northern Alberta, Canada. Process steps of the improved
process flowsheet
method extend through the sequential functions of oil sand excavation, primary
crushing, oil sand
transportation to a remote Oil Sand Receiving and Slurry Preparation Plant,
holding the oil sand in a
temporary surge storage facility at a distal Oil Sand Receiving and Slurry
Preparation Plant, and primary
crushed oil sand reclaimed and discharged to the feed chute of an oil sand
slurry preparation plant. This
latter facility is not described or claimed within the scope of this
disclosure. The technical fields of the
inventive method described and claimed herein is specifically that of Mining
and Bulk Materials
Handling.
Figure 1 illustrates a mobile excavator 1 prepared to dig oil sand from a
mining face in a mining pit (not
shown) and a mobile primary crusher 2, illustrated generally in relative
positioning of the mobile
excavator dumping oil sand from its bucket 3 into a receiving and storage
hopper 4, to be reclaimed by a
reclaiming conveyance 5 feeding to a primary crusher 6, discharging primary
crushed oil sand to a
discharging conveyance 7 which is fitted with a Tramp Metal Detection and
Alarm System. The
discharging conveyance 7 has both luffing and slewing capabilities and is able
to discharge the primary
crushed oil sand into a succession of mine haulage trucks (not shown) for
transportation to a distal Oil
Sand Receiving and Slurry Preparation Plant (shown in Figures 2 and 3). The
mobile primary crusher 2 is
mounted on suitable crawler tracks 9 and 10 with suitable turntable means
enabling unlimited
tramming mobility while working closely in cooperation with the mobile
excavator 1. The mine haulage
trucks are able to transport loads of primary crushed oil sand freely within
the mining pit areas between
the locations of the mining faces and the location of the distal Oil Sand
Receiving and Slurry Preparation
Plant.
The receiving and storage hopper 4 will have a design capacity to hold an
amount of run-of-mine (ROM)
oil sand ready to be reclaimed, crushed and loaded quickly into the mine
haulage trucks, having a
storage design capacity equal to about 2 bucket loads from the primary
excavator, to enable the mobile
primary crusher 2 to begin crushing the ROM oil sand and loading the mine
haulage truck as soon as the
mine haulage truck moves into its loading position. During the normal waiting
time between a first mine
haulage truck leaving with a full load and a second mine haulage truck moving
into a loading position
the mobile excavator 1 can continue to dig oil sand and fill the receiving and
storage hopper 4 with ROM
oil sand, thus benefitting the productivity of both the mobile excavator and
the mine haulage trucks.
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The tramp metal detection and alarm system 8 will be provided with variable
sensitivity to enable
sensing and alarming for large tramp metal such as replaceable teeth and
holders of the mobile
excavator, while not alarming for smaller tramp metal such as nuts and bolts
or small hand-tools which
would not damage, plug or stall downstream processing units. Upon detecting
and alarming the
presence of large tramp metal, an automated or manually operable metal removal
procedure will be
initiated, comprising the steps of stopping the reclaiming conveyance 5, the
primary crusher 2 and the
discharging conveyance 7, slewing the discharging conveyance 7 to the left or
to the right so as to
enable re-starting the discharging conveyance 7 to discharge the large tramp
metal onto the ground,
swinging the discharging conveyance back into its truck loading position and
restarting the reclaiming,
crushing and discharging functions. The tramp metal removal procedure is
unique in not requiring any
auxiliary structural or mechanical equipment to facilitate its function.
Figure 2 illustrates the first of two portions of a distal Oil Sand Receiving
and Slurry Preparation Plant
comprising a remote SB 12 mounted into a 3-sided recess of a Mechanically
Stabilized Earth (MSE) wall
13 constructed on a prepared grade surface 14 of the mining pit and having a
prepared elevated upper
surface 15 upon which the mine haulage trucks (not shown) are able to travel
and approach the remote
SB 12 for the purpose of dumping loads of primary crushed oil sand therein.
Concrete curbs 16 are
conveniently placed to surround the exposed remote SB 12 sitting in the 3-
sided recess of the MSE wall
13 at such a height and arrangement as to prevent the mine haulage truck from
accidentally falling into
the remote SB 12, but also to enable the mine haulage truck to back up to the
concrete curb 16 and
dump its load of primary crushed oil sand into the remote SB 12. Concrete
Curbs 16 are fitted with a
Sealing means 17 to prevent spillage. The remote SB 12 is fitted with an
inclined reclaiming and
transferring conveyance 18 to reclaim the primary crushed oil sand 19 from the
remote SB 12,
discharging the primary crushed oil sand 19 into a receiving chute 20 of an
oil sand slurry preparation
plant. The remote SB 12 has suitable support structural means 21 shown in
simplified form.
Preferred embodiments noted in Figure 2 are the use of the MSE wall to enable
the mine haulage truck
to dump primary crushed oil sand directly into the remote SB and the use of
the inclined reclaiming and
transferring conveyance 18; enabling the elimination of large heavy duty
inclined SB and SPP feed
conveyors, respectively, required in conventional art and industry practice.
For a typical 2-train
processing facility there are 4 such conveyors that can be eliminated, saving
the energy consumption
associated with up to 12,000 installed horsepower.
The function of the remote SB 12 when filled with the primary crushed oil sand
is to enable a steady
feeding supply of primary crushed oil sand to the oil sand slurry preparation
plant, even when the arrival
of mine haulage trucks may be temporarily delayed for any reason. The optimal
design capacity of the
remote SB can be calculated using BMH scientific strategies to establish the
frequency and duration of
typical causes of upstream delays, thereby to calculate a SB capacity capable
of covering a large
percentage of short term upstream delays. The typical live design capacity of
the remote SB in the
industry ranges from about 3,000 to 5,000 tonnes for single equipment trains
operating in the range of
6,000 to 8,000 tonnes per hour, but for this Improved Oil Sand Mining and
Haulage Method a smaller
the live storage capacity can be designed for the remote SB also counting the
live capacities of the mine
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haulage truck arriving and dumping fresh loads of the primary crushed oil sand
into the remote SB at a
frequency of about once every 1.5 minutes.
The inventive method of this disclosed patent application enables a very high
availability of the mining,
crushing and haulage functions achieved upstream of the remote SB due to
effective system de-coupling
and redundancy achieved, and the fact that the mine haulage trucks are
transporting primary crushed
oil sand instead of the ROM oil sand as in the case of conventional industry
practice.
Figure 3 is a partial view of the second of two portions of the distal Oil
Sand Receiving and Slurry
Preparation Plant, the second portion fed from the reclaiming and transferring
conveyance 18 which
reclaims and transfers primary crushed oil sand from the remote SB (item 12 in
Fig. 2) to the second
portion of the distal Oil Sand Receiving and Slurry Preparation Plant via the
receiving chute 20; the
second portion of the distal Oil Sand Receiving and Slurry Preparation Plant
lying outside of the scope of
this patent application. What is apparent from Figures 2 and 3 is that the
first portion and the second
portion of the distal Oil Sand Receiving and Slurry Preparation Plant are
constructed separately from but
in close proximity to each other, thus eliminating a large heavy duty inclined
slurry preparation plant
(SPP) feed conveyor required in conventional industry practice. For a typical
2-train processing facility
there are 4 such conveyors that can be eliminated, considering the usage of
the MSE wall enabling direct
dumping of the mine haulage trucks into the SB and the co-location of the SB
and SPP in close relative
proximity to each other.
Figure 4 is an overall block flow diagram for the Improved Oil Sand Mining and
Haulage Method, in
which the mobile excavator 1 digs oil sand from a mining face in a the mining
pit and dumps the oil sand
into a mobile primary crusher 2, which crushes and discharges primary crushed
oil sand onto a
discharging conveyance, which loads primary crushed oil sand into multiple
mine haulage trucks, which
transport the primary crushed oil sand to the remote SB 12; primary crushed
oil sand is then reclaimed
and transferred into the receiving chute 20 of a distal Oil Sand Receiving and
Slurry Preparation Plant.
Figure 4 also illustrates an overland conveyor 22 inserted between the mine
haulage trucks and the
remote SB.
Figure 5 illustrates a preferred embodiment of an overland conveyor 22
inserted between the mine
haulage truck (not shown) and the remote SB 12. The Overland Conveyor 22 is
fed from the OIL
conveyor belt loader 23 which receives the primary crushed oil sand from the
mine haulage trucks into a
loading hopper 24 having a capacity greater than one the truck dump load. The
0/L conveyor belt loader
23 is fitted with an inclined reclaiming conveyor 25 having a variable speed
drive 27 to enable loading
the primary crushed oil sand 19 onto the overland conveyor 22. The overland
conveyor 22 is fitted with
a variable speed drive (VSD) 26 to enable transporting and discharging the
primary crushed oil sand 19
into the remote SB 12 as illustrated and described for Figures 2 and 3, and
subsequently discharged by
the inclined reclaiming conveyor 25 into receiving chute 20 of the Oil Sand
Slurry Preparation Plant.
The use of overland conveyor 22 as a series-connected redundant transportation
link will not interfere
with continued access of the mine haulage truck to dump loads of primary
crushed oil sand directly into
the remote SB 12, the primary crushed oil sand being excavated from the same
mining faces and being
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crushed by the same mobile primary crushers whether delivered by the overland
conveyor or delivered
directly by mine haulage trucks.
The OIL conveyor belt loader 23 is illustrated with a raised loading hopper 24
and skirting along both
sides of the inclined reclaiming conveyor 25 and is equipped with a variable
speed drive (VSD) 27. The
operation of the preferred embodiment of the overland conveyor 22 using the
0/L conveyor belt loader
23 will rely upon mine haulage trucks dumping primary crushed oil sand on top
of the loading hopper of
the inclined reclaiming conveyor 25, thus forming an inverted cone of primary
crushed oil sand (not
shown) to bury the loading hopper and spilling a portion of the primary
crushed oil sand onto the
immediately surrounding area, the operation of the inclined reclaiming
conveyor 25 continually drawing
down the cone of primary crushed oil sand and discharging it onto the overland
conveyor 22; the cone
of primary crushed oil sand is therefore alternately re-formed and drawn down
again as multiple mine
haulage trucks continue to dump additional loads of primary crushed oil sand
onto the loading hopper
of the inclined reclaiming conveyor 25.
In the preferred embodiment of the overland conveyor 22 the operation of the
overland conveyor 22
and the 0/L conveyor belt loader 23 will be controlled automatically to fill
the remote SB 12 with
primary crushed oil sand, drawing-down the dumped loads of primary crushed oil
sand quickly in
anticipation of the arrival of another mine haulage truck load to be dumped.
Assuming a minimum cycle
time of 3 minutes per mine haulage truck arrival, and 3 0/L conveyor belt
loaders in service
simultaneously, each operating at a reclaiming rate of 120 tonnes per minute
leads to an aggregated
design loading rate of 21,780 tonnes per hour from multiple ones of the 0/L
conveyor belt loaders 23 to
the overland conveyor 22, which is more than enough capacity to meet a
combined 2-train design
throughput demand rate of 12,000 to 14,000 tonnes per hour. On that basis the
minimum design
capacity of the overland conveyor could be set at about 18,000 tonnes per
hour, enabling the mining
and haulage functions to re-fill the remote SB quickly following any short
term upstream delay event but
also relying on a control strategy for the 0/L conveyor to prevent over-
filling of the remote SB.
In the preferred embodiment of the overland conveyor 22 a first controller 28
will control the loading of
the primary crushed oil sand onto the overland conveyor. The first controller
28 will comprise belt load
sensing devices 29 on the 0/L conveyor operative with the VSD drive speed
controller 27 on the inclined
reclaiming conveyor 25. The belt load sensing devices 29 will be located
within a few meters of the
loading point. The overland conveyor can receive primary crushed oil sand from
multiple different
mining faces simultaneously via multiple independent 0/L conveyor belt loaders
located along its length.
The operation of the first controller 28 at each of the OIL conveyor belt
loaders will compare the actual
belt loading rate against a set point corresponding to that of a fully loaded
belt and will operate the VSD
drive controller to meet but not exceed the fully loaded belt weight per
meter. Each the 0/L conveyor
belt loaders 23 will therefore have installed e a dedicated set of its own
independent and integrated belt
load sensing devices 29, the VSD drive speed controller 29 and a first
controller 28.
In the preferred embodiment of the overland conveyor 22 a second controller 30
will control the filling
of the remote SB 12, an SB level sensor 31 providing feedback control signal
to regulate the speed of the
overland conveyor via the second controller 30 and VSD speed control 26.
Should the SB level sensor 31
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detect a low level of primary crushed oil sand in the remote SB the VSD drive
controller 30 will operate
the overland conveyor at full rated speed to maximize the flow rate of primary
crushed oil sand
discharging into the remote SB. Should the level sensor 31 detect a high level
of primary crushed oil
sand in the SB 12, the VSD drive controller 26 and the second controller 30
will reduce the speed of the
overland conveyor, including coming to a complete stop should the level
sensing indicate a completely
full condition of the remote SB.
The integrated operation of the overland conveyor and the OIL conveyor belt
loaders will therefore
prioritize the filling of the remote SB to a design set point level via the
second controller 30 controlling
the speed of the conveyor drive. Independently, each of the 0/L conveyor belt
loaders 23 will maximize
the rate of transferring primary crushed oil sand received from the mine
haulage trucks to the 0/L
conveyor, constrained by the first controller 28 which controls the speed of
the inclined reclaiming
conveyor 25 to prevent overloading the overland conveyor. Each of the 0/L
conveyor belt loaders 23
will therefore operate at full speed unless constrained either by the presence
and amounts of previously
loaded oil sand transported on the overland conveyor as determined by the
first controller 28 or by the
second controller 30 having reduced the speed of the overland conveyor. In no
case will the first
controller 28 allow overloading of the overland conveyor, regardless of the
controlled operating speed
of the overland conveyor.
It should be noted that the usage of the overland conveyor 22 to supplement
the haulage function of
the mine haulage truck will add two new inventive features to the overall
Improved Oil Sand Mining and
Haulage Method; firstly increasing the redundancy factor of alternate delivery
means for transporting
the primary crushed oil sand to the remote SB, and secondly providing an
additional source of live surge
storage capacity of primary crushed oil sand available to be transferred into
the remote SB.
The operation of the overland conveyor 22 discharging primary crushed oil sand
into the remote SB
supplements the mine haulage truck dumping primary crushed oil sand into the
remote SB, delivering
primary crushed oil sand from any operating mining face or from any other
source of suitably prepared
the oil sand in the open pit mining operation.
The second new inventive feature gained by usage of the overland conveyor 22
is the availability of
additional live surge storage capacity of primary crushed oil sand incremental
to the aggregated live
capacities of the remote SB 12 and the live capacities of the mine haulage
trucks transporting primary
crushed oil sand to be dumped into the remote SB. For example, if the overland
conveyor 22 had a
length of 4 kilometers and a design load capacity of 18,000 tonnes per hour,
the additional live fully
loaded capacity could be as much as 3,636 tonnes of primary crushed oil sand
lying on the carrying belt
surface of the 0/L conveyor.
Corollary surge storage capacity is also available by using auxiliary pit
maintenance equipment to load
residual cones of primary crushed oil sand left over from the dumping of the
mine haulage trucks onto
the loading hoppers of inclined reclaiming conveyors 25 as a clean-up
function. Since both of the
sources of primary crushed oil sand are incremental surge capacities available
after stoppage of all the
mine haulage truck, this additional live capacity could be used to mitigate
minor upstream delays such
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as shift changes, severe weather events or other stoppages without reducing or
stopping continuous
primary crushed oil sand feed delivery to the Oil Sand Slurry Preparation
Plant.
It should be noted that this Improved Mining and Haulage Method can service a
"single", "double" or
"triple" remote SBs feeding corresponding "single", "double" or "triple" SPP
trains, all structural
elements of which can be located on a single small footprint site, with
appropriate decreases or
increases in the numbers of mobile excavators, mobile primary crushers and
mine haulage trucks
comprising the mining equipment fleet.
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