AU2001247301A1

AU2001247301A1 - Method and system for mining hydrocarbon-containing materials

Info

Publication number: AU2001247301A1
Application number: AU2001247301A
Authority: AU
Inventors: Ronald D Drake; Michael Helmut Kobler; John David Watson
Original assignee: Osum Oil Sands Corp
Current assignee: Osum Oil Sands Corp
Priority date: 2000-03-13
Filing date: 2001-03-07
Publication date: 2001-12-06
Anticipated expiration: 2021-03-07

Description

METHOD AND SYSTEM FOR MINING HYDROCARBON-CONTAINING MATERIALS

FIELD OF THE INVENTION The present invention is related to the mining and/or processing of soft-ore deposits generally and to the mining and/or processing of bitumen-containing materials, such as oil sands, specifically.

BACKGROUND OF THE INVENTION Oil is a nonrenewable natural resource having great importance to the industrialized world. Over the last century, the consumption of oil has increased dramatically and has become a strategic commodity, leading to the development of alternative sources of crude oil such as oil sands and oil shales. As used herein, oil sands are a granular or particulate material, such as an interlocked skeleton of sand, with pore spaces occupied by bitumen (an amorphous solid hydrocarbon material totally soluble in carbon disulfide), and oil shale is a rock containing kerogen (a carbonaceous material that which gives rise to crude oil on distillation). The vast majority of the world's oil sands deposits are found in Canada and Venezuela. Collectively, oil sands deposits contain an estimated 10 trillion barrels of in- place oil. Oil shales are found worldwide with large deposits in the U.S. Collectively, oil shale deposits contain an estimated 30 trillion barrels or more of in-place oil. It is to be understood that a reference to oil sands is intended to include oil shales and vice versa.

Bitumen is typically an asphalt-like substance having an API gravity commonly ranging from about 5° to about 10° and is contained within the pore space of the oil sands. Bitumen cannot be recovered by traditional oil well technology because it will not flow at ambient reservoir temperatures. To overcome this limitation, near surface oil sand deposits are excavated by surface mining methods, while bitumen in deeper deposits is recovered by in situ techniques, which rely on steam or diluents to mobilize the bitumen so that it can be pumped out by conventional oil recovery methods. The bitumen is recovered from the surface excavated oil sands by known separation methods, and the bitumen, whether derived from surface mining or in situ processes, sent to upgrading facilities where it is converted into crude oil and other petroleum products. Underground mining techniques have been largely unsuccessful in mining deeper oil sands due to high mining costs and unstable overburden conditions. Existing methods for recovering oil from oil sands have numerous drawbacks. Surface mining techniques are typically only economical for shallow oil sands deposits. It is common for oil sands deposits to dip and a significant part of the ore body may be located at depths that are too deep to recover by surface mining methods. As a result, most of the oil sands deposits are unprofitable to mine. Surface mining requires large areas to be stripped of overburden which then must be moved to other areas for storage. The tailings from the bitumen separation process typically require large tailings ponds complexes in which the tailings are treated before the mined land can be reclaimed. The costs of stripping overburden, building and maintaining tailings ponds and eventual land reclamation costs can be high, particularly for deeper oil sands deposits. Because of the large scale of these operations, the short and long term environmental impact and associated costs of surface mining can be substantial. In situ techniques are disadvantaged in that a relatively large amount of energy is consumed per unit energy recovered in the bitumen.

A significant portion of oil sands deposits lie too deep for economical recovery by surface mining and are too shallow for effective in-situ recovery. Other oil sands deposits, though located at shallow depths, are located under surface features that preclude the use of surface mining. For example, oil sands deposits can be located under lakes, swamps, protected animal habitats and surface mine facilities such as tailings ponds. Estimates for economical grade bitumen in these in-between and inaccessible areas range from 30 to 100 billion barrels.

SUMMARY OF THE INVENTION These and other needs are addressed by one or more of the various inventions discussed herein. Certain of the inventions relate to excavating materials, particularly soft- ore or sedimentary materials, by underground mining techniques. The material excavated by these methods can be any valuable material, particularly in-situ or in-place hydrocarbon- containing materials, such as found in oil sands, oil shales, conventional oil reservoirs, coal deposits and the like, as well as other valuable minerals such as bauxite, potash, trona and the like. L a first embodiment, the present invention provides an underground mining method in which the material is excavated, continuously, semi-continuously, or episodically, by an underground mining method such as a continuous mining machine, drill-and-blast, longwall mining, hydraulic mining, mechanical excavation whether by backhoes, hydraulic hammers and the like, or by tunnel boring machines ("TBMs") or any other appropriate underground mining practice. A movable shield may be used to provide ground support over the mining apparatus and personnel during excavating. In one configuration, a substantially smaller tunnel liner is formed within the excavation shield and left in place behind the moveable excavation shield as it advances. A backfill material is placed in the excavated volume behind the excavation machine and around the access tunnel liner. Preferably, the backfill at least substantially fills the unsupported volume and itself is supported by the tunnel liner and, in part, by the excavation shield and/or a bulkhead. Typically, the backfill (i.e., the solid particulates and associated interstitial or interparticle spaces) fills at least about 65%, more typically at least about 75% and even more typically from about 85 to about 100% by volume of the space defined by the access tunnel liner, the mining machine bulkhead, the bulkhead (or backfill retaining member) at the excavation entry, and the surrounding excavation. The excavation shield, bulkhead, backfill material and/or tunnel liner all act to support the unexcavated ground behind the excavation face. This combination provides ground support for the mining operation and a small trailing tunnel or passage for ingress and egress from the working face. The backfill material can be tailings from material processing operations, previously mined material, currently mined material, or any other material having acceptable density and strength characteristics.

The backfill operation can be accomplished by numerous techniques. For example, a prefabricated liner having a smaller outer boundary than the surface of the excavation can be set in place anywhere behind a rear section of the movable shield, and, before, during, or after advancement of the shield, the backfill material is injected or otherwise placed in the gap or space between the liner, the machine bulkhead, previously backfilled material, and the surrounding excavated opening. The trailing tunnel is defined by and extends through the liner.

In another configuration, the liner is formed beneath the shield such as using a suitable form, and the lining material placed in or on the form and allowed to set or become self-supporting while the overlying shield is in position. The liner can be formed from any suitable, preferably consolidated, material, such as concrete, grout, asphalt, or a combination thereof. The lining material could include previously excavated material, whether or not processed for bitumen recovery. When the liner is formed, the backfill material can be placed in the gap by suitable techniques. Before injection into the open space above the liner, the excavated backfill material could be combined with a suitable binder, such as flyash, gypsum, sulphur, slag, and the like, which will consolidate or strengthen the backfill material after injection into the open space.

In another configuration, the access tunnel is formed without a liner by combining the backfill material with a binder, such as those described above, placing the backfill material in place above a tail shield and/or form, permitting the backfill material to consolidate and become self-supporting while the tail shield and/or form is in position, and thereafter moving the tail shield, removing the form. Alternatively, the form could be left in position to further support the consolidated backfill.

The trailing tunnel in the backfilled portion of the excavation is preferably substantially smaller in cross-sectional area than the same portion of the excavation before backfilling. Preferably, the cross-section area of the trailing tunnel (in a plane normal to the direction or bearing or longitudinal axis of the excavation) is no more than about 30%, more preferably no more than about 20%, even more preferably no more than about 10% and most preferably ranges from about 5 to about 10% of the cross-section area (in the same plane) of the excavated portion of the mined volume. The backfilling of the excavation to define a trailing access tunnel can have numerous advantages. For example, the trailing access tunnel can have a cross-sectional area normal to the long axis of the trailing tunnel that is small enough to reduce significantly the likelihood of caving of the excavation during excavation, thereby providing enhanced safety for personnel, or of surface subsidence after the excavation is completed. This is particularly advantageous in weak overburden conditions, which are typically encountered in oil sand excavation. Backfilling can be significantly less expensive and more effective than conventional ground support techniques. Backfilling can provide a convenient way of disposing of waste materials, such as potentially toxic tailings (e.g., clean sands with a high concentration of clay and shale, etc.) or country rock (i.e., excavated material containing unprofitable levels of bitumen or devoid of bitumen), that are generated during excavation and/or material processing. Large surface facilities are not required for tailings or overburden storage. Reclamation costs, as well as short and long term environmental impacts, can thus be greatly reduced. The per-tonne costs of mining using any of the methods disclosed herein can be the same as, or even less, than the per-tonne mining cost of surface mining techniques on shallow deposits. Due to the high level of long-term ground stability associated with backfilling, the mining techniques disclosed herein can provide economical access to valuable materials in formerly unaccessible areas, such as under industrial facilities or protected or otherwise reserved areas, lakes, swamps, muskeg., etc. The methods disclosed herein can not only recover bitumen in oil sands deposits previously not economically recoverable by surface mining or in situ techniques but also can recover bitumen in oil sands deposits previously recoverable only by in situ techniques . The methods are often preferable to in situ techniques (such as thermal in-situ or chemical in-situ recovery processes) due to substantially less energy expenditure per unit of recovered bitumen. The methods can recover a substantially higher portion of the economically viable oil sands resource (generally regarded as those oil sands containing at least 5% to 6% by mass of bitumen) even in the presence of complex and variable mud and shale layers within the payzone.

In another embodiment, the excavated material is fully or partially processed in the underground excavation to recover the valuable components of the material. The material can be excavated using any mining process, including those described above. In one configuration, the excavated material is further comminuted in the excavation, such as by a crusher and/or grinder, formed into a slurry, and hydrotransported out of the excavation for further processing. The waste material, or tailings, can be formed into a second slurry at an external location and hydrotransported back into the excavation for use in backfilling. Alternatively, the backfill slurry can be formed from a high proportion of mature fine tailings ("MFTs") from previous surface mining operations and thereby provide for environmentally safe disposal of these wastes. The tailings from the excavated oil sands are processed to remove sand (which is a relatively valuable commodity and/or may be disposed of readily) and the sands replaced in the second slurry formed from MFTs and other less valuable tailings components, such as from both the present and previous mining operations. Surge tanks can be used to handle fluctuations in the slurry volume. In yet another embodiment, a tunnel boring machine is provided that is particularly suited for use in unstable overburden conditions. As used herein, a "tunnel boring machine" or TBM refers to an excavation machine including one or more movable shields for ground support. Typically, the TBM will be a rotary excavator including a shield, an excavating or cutting wheel and some wheel-driving apparatus. In one configuration, the hood of the forward portion of the movable shield(s) controls overburden and protects the excavation area, the body of the shield(s) houses the working mechanisms and one or more tail shields furnish ground support during the tunnel lining installation. In the typical TBM design, the cutting wheel is designed to perform three main functions : excavating, spoil removal and face support. The TBM can have one or more mining devices at its forward end. Such mining devices can be any suitable ground removal device, such as a rotary cutting head, a hydraulic jet, a shovel, a backhoe, a ripper or any combination of these devices. In the case of a rotary cutting head, an array of drag bits, an array of picks, an array of disc cutters and the like or any combination of cutting tools arrayed on the cutting head may be used. In another configuration, a tunneling machine can also be fully enclosed (a closed face machine) and capable of applying a pressurized slurry at the cutting face to provide, for example, stability to the excavation face. These machines are often referred to as slurry or slime machines or as earth pressure balance machines or as earth pressure balance systems.

In one configuration, the tunneling machine includes two or more shields of different sizes may be used to provide ground support. In one configuration, a large shield (in cross- sectional area) maybe located at the front of, over, and/or behind the machine to support the ground over the excavation and backfill operations. A small shield (in circumference) may be located behind the large shield and used to support the ground above the trailing access tunnel until the access tunnel becomes self-supporting or assembled.

In one configuration, the machine includes two or more (typically overlapping) tail shields or tail shrouds, each providing ground support. For example, a backfill tail shield, having substantially the same circumference as the main excavation surface (in the same plane), can extend behind the primary excavation shield to protect the backfill injection apparatus and the backfill volume from loose and falling ground from the unexcavated material. A typically substantially smaller tail shield (in circumference determined in the same plane) can extend behind the primary excavation shield and/or machine bulkhead to provide protect liner fabrication personnel and machinery from loose or falling ground or from previously backfilled material, until the liner has achieved sufficient strength to provide such protection. A binocular tunneling machine may have two large backfill shields and one or more smaller (in cross-section) access tunnel tail shields.

In one configuration, the body member has a plurality of interconnected segments that movably engage one another. In one design, the adjacent segments are interconnected by a plurality of hydraulic jacks or cylinders. The hydraulic cylinders on the trailing section can push against the liner or backfill material to advance the trailing section, thereby more effectively engaging adjacent liner sections and/or compacting the backfill material. In one design, the adjacent segments telescopically engage one another. The machine can have any number of segments including only one, though two or more segments are preferred. The segmentation allows the machine to change direction efficiently and allows the machine to follow the meandering oil sands deposits. In one embodiment, the segmentation also permits the machine to advance, one segment at a time, by the moving segment thrusting against the combined static friction of the stationary segments.

In one configuration, the segmented machine is propelled forward by a combination of soft-ground grippers and thrusting off the backfill material. The grippers can be of any suitable design, as will be appreciated by those of ordinary skill in the art. Soft-ground grippers are typically hydraulically actuated pads that can be thrust out against the sides of the excavation. The pads maybe large so as to contact a large area of a soft-ground ore body. Each section or segment of the tunneling machine can further include one or more such grippers for displacing and maneuvering the machine and providing thrust for the mining device(s) at the forward end of the machine. The rear segment of the machine can thrust off the backfill since the cross-sectional area or outer periphery of backfill is approximately the same as the cross-sectional area or outer periphery of the excavation. This form of propulsion also has the advantage of helping to compact and consolidate the backfill. In one configuration, the TBM includes a global positioning system and/or fibre optic surveying line to continuously determine the position of the machine.

In one configuration, the TBM includes one or more sensing devices for detecting the presence of hydrocarbons or other valuable components or barren ground or shale and calcite lenses and the like or another characteristic in the in-situ material to be excavated, and/or the presence or hydrocarbons or other valuable components material that has been excavated. The sensing devices can use sonar and/or ground-penetrating radar or other short range underground detection technologies to sense the features ahead of the mining machine.

In one configuration, the TBM machine has features permitting the TBM to change direction or steer. Such machines can steer by any number of means or combination of means. For example, a segmented machine can steer by extending and retracting its connecting hydraulic propulsion cylinders by different lengths of extension or retraction around the circumference of the machine. A TBM machine may change direction by differentially extending, retracting and reorienting the cutter tools on its rotary cutting head to assist in steering. The TBM may also steer by articulating its cutting head. The TBM may also deploy large flaps or grippers to create increased drag on the side of the machine so as to cause the machine to steer in that direction. Such maneuverability permits the TBM to mine patterns such as described herein as well as mine around barren ground or around obstacles. As will be appreciated, the above methods of steering may be varied to suit the local conditions and can be combined or used in other configurations or embodiments that may be different from those set forth above.

In one configuration, the tunneling machine has an excavation head configured to form an approximately rectangular excavation cross-section which may be more suited to some ore bodies. A rectangular excavation can be formed by rotary cutting head assemblies in a number of ways which include assembling an array of circular cutter heads, tilting a circular head and using one or more triangular heads that rotate eccentrically by the use of offset planetary gear drives for example. The preferred embodiment for excavating a rectangular opening would incorporate two or more conventional tunnel boring machine heads in a binocular or even trinocular TBM configuration. Such machines have been built and used in various civil tunneling applications. In one configuration, the tunneling machine is configured to excavate the in situ material by slurry techniques so that the mined material is immediately formed into a format that is compatible with slurry pipeline or hydrotransport methods. In this configuration, the mined material is typically not handled as a solid and thus tends to be less abrasive and cause less wear on any of the materials handling apparatuses. In one configuration, the tunneling machine includes a hydrocarbon extraction unit, such as a bitumen separation apparatus. The apparatus extracts the hydrocarbons and the extracted hydrocarbons are transported to a surface facility for further processing. In this manner, less material can be transported to the surface, thereby decreasing haulage costs. The waste material, which is still in the excavation area can be used for backfilling as noted previously. In one configuration, the tunneling machine includes a heat exchange system for absorbing heat from any heat sources in the tunneling machine, such as the propulsion motors and hydraulic cylinders used to move the machine segments, and transferring the absorbed heat to the material in a slurry formed at or near the cutting head, the bitumen processing chamber, personnel compartment, lining material formation units, and/or the hydrotransport system. The heat exchanger can be of any design, as will be appreciated by those of ordinary skill in the art.

In one configuration, the tunneling machine includes a pressurized chamber having a pressure greater than the formation pressure of the unexcavated material to inhibit formation gases such as methane from entering personnel areas. The method can require only a small fraction, typically less than 5% to 10%, of the output crude oil energy, to power the excavation and bitumen recovery process.

In one configuration, the mining machine further includes device(s) for forming tunnel lining sections. Such devices can be forms, lifting devices such as cranes to manipulate the forms or prefabricated liners, injecting assembly for injecting or spraying the backfill material around the liner, asphalt formation machine(s) for forming a lining material, concrete mixing machine(s), machines for extruding cast-in-place liners and the like.

The foregoing summary is neither complete nor exhaustive. As will be appreciated, the above features can be combined or used in other configurations or embodiments that may be different from those set forth above. For example, one or more of the features can be used in mining processes that do not use the backfill feature. Such other configurations and embodiments are considered to be part of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a cross-sectional a view of a mining machine of the present invention excavating a soft ore deposit. Figure 2 shows an isometric front view of the mining machine of the present invention.

Figure 3 shows an isometric rear view of a large excavating machine with two rotary cutter heads. Figure 4 shows a side view of a possible layout for the principal interior components of a TBM mining machine.

Figure 5 shows a sequence of cross-sectional side views of the mining process of the present invention.

Figure 6 shows front views of various arrays of rotary cutter heads. Figure 7 shows several views of a slurry cutter head assembly.

Figure 8 shows an isometric schematic view of a machine that can lift and turn a large TBM.

Figure 9 shows a flow chart of the oil sands material as it passes through the mining machine. Figure 10 shows a flow chart of the oil sands material as it passes through the mining machine where bitumen is separated from the oil sands in the machine.

Figure 11 shows a side schematic view of a TBM mining machine illustrating the volumes occupied by both outgoing oil sand or bitumen slurry and incoming tailings slurry.

Figure 12 shows a possible embodiment of a heat exchange system for heating a slurry at the working face.

Figure 13 shows a side view of a sequence of machine motions utilizing differential friction as a means of propulsion.

Figure 14 shows a side view of several means for a large shield machine to execute an underground turn. Figure 15 shows sequence illustrating how a large mining machine of the present invention can execute an underground turn.

Figure 16 shows an isometric view of a possible extruded access liner which contains pipelines and other ducts and conduits formed within the liner material.

Figure 17 shows an isometric view of an excavating machine with two triangular cutter heads. Figures 18a and b are side and rear views, respectively, of an excavating machine according to another embodiment.

DETAILED DESCRIPTION Overview of the Method

The method described in the present invention can be adapted to underground mining of deposits that are relatively easy to excavate by known technologies but require ground support behind the advancing machine to avoid cave-ins, surface subsidence or ground heaving. This invention involves, in part, substantially reducing the cross-section of the trailing tunnel with respect to the cross-section of the ground excavated and therefore removes the requirement for expensive ground support while eliminating any significant ground movement of the unexcavated ground. The invention reduces the economics of underground recovery to approximately those of currently practiced open-pit mining operations and possibly less since it eliminates the need to remove overburden and can reduce the size of tailings ponds required.

Figure 1 shows a cross-sectional a view of a tunneling machine 100 mining into a buried oil sand deposit 103 from a prepared face 101 which has been formed by removing overburden material 102 to expose the oil sand deposit 103. The oil sand deposit 103 typically lies on top of a basement rock 104 and under the overburden 102. The mining machine 100 advances and mines into the oil sand 103 by excavating oil sand material 103 through the front end 105 which may be, for example, a rotary cutter head. As the mining machine 100 advances, an access tunnel liner 106 is formed inside the machine 100. As the machine 100 advances, the liner 106 remains in place and is left behind the advancing machine 100. Also as the machine 100 advances, material is deposited as backfill 108 behind the machine 100 through one or more openings in the rear 107 of the machine 100. The backfill 108 surrounds the liner 106 leaving an access tunnel 109. The machine 100, the liner 106 and the backfill 108 all act to support the remaining oil sand 103 and overburden 102 such that there is insignificant motion of the ground surface 110. A ramp 111 which allows the mining machine 100 to position itself in at the entrance portal 112 for the start of its mining drive is also shown. Figure 2 shows an isometric front view of the mining machine of the present invention illustrating a typical size comparison of the excavation cross-section and the trailing access tunnel cross-section. In soft ground or soft rock, tunnel boring machines can be advanced by thrusting against the tunnel liner structure which has approximately the same cross-sectional geometry as the boring machine. In one embodiment of the present invention, only a small tunnel liner is left behind so the machine must be propelled forward by other means. In this configuration, the mining machine may be formed, for example, by two telescoping segments and propelled forward by conventional soft-ground grippers which thrust against the walls of the excavation and by the aft most segment thrusting against the backfill or by a combination of both means of propulsion. In the present invention, it may be necessary to use large soft-ground grippers to provide machine propulsion and cutter head thrust as (1) the only means of propulsion and thrust; or (2) as the principal means of propulsion and thrust where the machine can also thrust against the backfill when additional propulsion and thrust are required; or (3) as an auxiliary means of propulsion and thrust where the principal means of propulsion and thrust are against the backfill. This combination of propulsion and thrust techniques allows the backfill operations to be decoupled from the propulsion and cutter head thrust. This combination also allows the backfill to be compacted separately from propulsion and cutter head thrust.

Figure 2 shows an example of a tunnel boring mining machine 300 that can be propelled by using external grippers 301 and 302. The rear section 303 of the machine is shown with full circumferential grippers 302 that grip by being pushed out against the excavation walls, usually by hydraulic rams. When the rear section 303 grippers 302 are pushed out against the excavation walls, the forward section 304 of the machine, which includes the cutter head 305, can thrust forward by pushing against the rear section 301. Once the forward section 304 is fully or almost fully extended, then the retracted grippers 301 on the forward section 304 can be pushed out against the excavation walls while the grippers 302 on the rear section 303 are retracted. Now, hydraulic cylinders inside the machine (not shown) can retract and draw the rear section 303 of the mining machine forward. This is an example of a propulsion cycle for a two segment machine. As noted previously, the rear section can also thrust off the backfill 306 behind the machine and around the trailing access tunnel 307, if necessary. The diameter 308 of the mining machine 300 is typically in the range of about 10 to about 20 meters. The trailing access tunnel 307 is much smaller in cross-sectional area having a typical dimension 309 in the range of about 2.5 to about 4 meters.

Figure 3 shows an isometric rear view of a large excavating machine 400 with two rotary cutter heads 401 and 402 that can excavate a roughly rectangular excavation opening and leave a small trailing access tunnel. The rotation of the cutter heads 401 and 402 may synchronized so that the areas excavated by each have some overlap. The cutter heads 401 and 402 may also be counter rotated to substantially reduce the tendency of the machine 400 to roll. The smaller cross-section trailing access tunnel tail shield 403 is shown extending from the rear of the advancing machine. As an example, four backfill or spoil discharge pipes 404 for injecting backfill material in the volume behind the advancing machine are shown protected from falling ground from above by a large tail shield 405. The trailing access tunnel liner is formed inside the machine 400 and protected from falling ground and backfill material by the smaller tail shield 403. The diameter 406 of one of the cutter heads of the mining machine 400 is typically in the range of about 7 to about 15 meters and the cross-sectional area excavated by the machine 400 is therefore about twice the cross-sectional area of one cutter head. The trailing access tunnel tail shield 403 is much smaller in cross- sectional area having a typical dimension 407 in the range of about 2.5 to about 4 meters. Figure 4 shows a possible layout for the principal interior and exterior components of a TBM mining machine of the present invention. The cutter head assembly 500 is driven by a main cutter head motor (not shown) through a main bearing 501. The cuttings are directed into a crusher 502 and then into a muck chute 503 which may be housed in a pressurized chamber 504. The muck chute 503 goes through a bulkhead 505 and into a large enclosure 506 which may be a bitumen separator or a surge tank or an apparatus for forming an oil sands slurry. Also shown are hydraulic cylinders 507 for propulsion and steering and electric motors 508 for power. The oil sand ore or bitumen is sent out of the access tunnel 509 via a slurry pipeline 510. The backfill material, whether produced in the machine by a bitumen separator apparatus or externally and hydrotransported into the machine via a slurry pipeline 510, is sent to a de- watering apparatus 511 where the de- watered backfill material is transported to discharge pipes 512 for backfilling the volume inside the large tail shield 513 and around the small tail shield 514 in which the access tunnel liner 509 may be formed. In this configuration, the hydraulic cylinders 508 can be used to push or pull the interior bulkhead 515 with respect to the rear bulkhead 515. The cylinders 508 may pull the rear bulkhead 516 forward to allow backfill material to be discharged and to advance the rear segment 518 of the mining machine. The cylinders 508 may also push against the rear bulkhead 516 to compact the backfill material and to advance the forward segment 517 of the mining machine. The rear cross-sectional view also shows utility lines 519 (water, electrical, sewage for example) and a ventilation duct 520.

As will be appreciated, the bitumen separator apparatus in the machine can perform bitumen extraction by any of a number of techniques. For example, the separator can use the Clark process in which caustic is added to an agitated hot water slurry (about 80C) of the oil sands with the bitumen separation being completed by flotation processes. Other methods eliminate the addition of caustic and use greater amounts of mechanical agitation at a lower water temperature to separate the bitumen.

Mining Process

The backfilling operations envisioned by the present invention can be carried out in a number of ways. In one configuration, the aft most section of the machine may be advanced creating a free volume behind the machine and under the large tail shield. In this case, previously place backfill may slump into this volume. Thereupon, backfill material may be injected or otherwise placed into the volume behind the advancing machine. The erection and extension of access tunnel liner segments or extrusion of a cast-in-place liner can take place independently of the backfilling process. The following drawings illustrate three variants on the method of the present invention

Figures 18a and b shows a side view and a rear view of a mining machine typical of the present invention illustrating a large backfill tail shroud and a small access tunnel tail shroud. Figures 18a and b respectively show a side view cross-section 1300 and a rear view cross-section 1301 of a generic mining machine 1302 that is part of the present invention. The machine includes a primary ground support shield 1303. The top portion of the shield 1304 is called a hood and controls the overburden and protects the excavation area. The body of the shield 1303 houses the working mechanisms of the machine including the means of excavation 1305 at the front of the machine 1300. The shield 1303 maybe extended past the rear of the machine to form a tail shield 1306 which can protect the rear of the machine during the backfilling operations. The machine 1300 may also include a substantially smaller (in cross-section) liner tail shield 1307 which furnishes ground support during the installation process for an access tunnel liner. Preferably, the cross-sectional area enclosed by the liner tail shield (in the plane of the page) is no more than about 30%, more preferably no more than about 20%, even more preferably no more than about 10% and most preferably ranges from about 5% to about 10% of the cross-sectional area (in the same plane) of the area enclosed by the large tail shield (which includes the area enclosed by the liner tail shield), hr the rear view, the muck discharge ducts 1308 are shown. These ducts 1308 expel backfill material into the excavated volume behind the machine as the back section of the machine is advanced.

The backfilling operations envisioned by the present invention can be carried out in a number of ways. In one configuration, the aft most section of the machine may be advanced creating a free volume behind the machine and under the large tail shield. In this case, previously place backfill may slump into this volume. Before, during or after advancement, backfill material may be injected or otherwise placed into the volume behind the advancing machine. The erection and extension of access tunnel liner segments or extrusion of a cast-in-place liner can take place independently of the backfilling process. The following drawing illustrates a more preferred method of the present invention in which the backfill is continuously injected so as to leave no significant free volume behind the advancing machine. Alternately and more preferably, the tunnel liner may be formed by extruding concrete between two moveable forms to form a tunnel liner. In this embodiment, concrete may be mixed in a batch plant near the tunnel portal and slurried into the excavation machine, or may be mixed in a batch plant contained in the excavating machine. The concrete can then be pumped into the space between the moveable forms. The forms are initially located within the mining machine. As the machine advances, the forms remain stationary until the concrete has set and then the forms are withdrawn back into the machine, leaving the concrete tunnel liner in place with enough strength to support the backfill material and any other material that is not supported as a result of the excavation process. Figure 5 shows a sequence of cross-sectional side views of a more preferred embodiment of the mining process in which the access liner is formed by continuously extruding a liner and the backfill is continuously deposited so as not to leave any empty volume behind the machine. In Figure 5a the mining machine 1600 is shown with a cutting head 1601 and an internal apparatus 1602 for depositing backfill material 1603 through a rear bulkhead 1604 into the volume behind the machine 1600. A liner shield 1605 is shown in which the extruded liner 1606 is assembled. The extruded liner is formed by an apparatus 1607 contained in the mining machine 1600. The liner form 1609 may have strengthening ribs 1608 cast as part of the liner structure. In Figure 5b, the front of the machine 1600 advances pulling the backfill apparatus 1602, the liner shield 1605, the liner extrusion apparatus 1607 and the liner form along with it but not far enough to uncover the extruded liner portions that have not attained the level of strength to support the backfill 1603. The rear of the machine 1600 remains in place along with the rear bulkhead 1604. hi Figure 5c, the rear of the machine 1600 and the rear bulkhead 1604 are moved forward while backfill material is continuously deposited into the volume immediately behind the moving rear bulkhead 1604. During this part of the cycle, the cast-in-place or extruded liner 1606 continues to be formed under the liner tail shield 1605. In Figure 5d, the front portion of the machine 1600 has been advanced and is in the same state as in Figure 5b except that additional extruded liner 1606 length has been added. This embodiment is preferred over the pre-cast liner segment embodiment because it requires less labor and is more readily automated. The extruded liner may be formed from any of a number of fast-setting concretes, for example, which utilize accelerants to cause the concrete to achieve a reasonable strength level in a period typically of less than a hour.

As will be appreciated, any suitable rotary cutter head design can be employed for the machine. By way of example, Figure 6 shows front views of various ways in which arrays of rotary cutter heads can be arranged to excavate circular or rectangular openings. As will be appreciated, any suitable rotary head design can be used to form an excavation with an approximately circular cross-section. A machine with a single rotary cutter head will be unable to form a more desirable opening with a rectangular cross section and will have a tendency to roll in the direction of head rotation. These deficiencies may be substantially reduced by assembling a machine in which multiple rotary cutting heads are arranged in various ways. A machine with a excavating head comprised of an array of smaller conventional rotary boring heads is illustrated in Figure 6a. Such an array of heads 1710 would be mounted in a large frame structure 1711 that forms the front-end of a tunnel boring machine and would be capable of excavating an approximately rectangular opening. As the rotary heads advance through the oil sands deposits, the material that passes in the areas 1712 between adjacent heads will be partially broken down by the agitation of the rotary head motion, especially if adj acent heads are rotating in opposite directions . This material can be further reduced in size distribution by a primary crusher located in the machine to reduce the larger rock and sands accretions to a size amenable to hydrotransporting. Only the material adjacent to the four corners 1713 of the machine may be by-passed by this array of boring heads. In the geometry illustrated, the by-passed material would be about 3% of the total material in the rectangular cross-section shown. Figure 6b illustrates yet other configurations of rotary cutter heads that can be used to excavate an approximately rectangular opening and better comminute the ore. This machine 1720 has three large cutting heads 1721 , 1722 and 1723. The large center head 1722 is shown mounted ahead of the two large side cutting heads 1721 and 1723 so that the cutting cross-sections overlap. Smaller cutting heads 1724 are mounted in the spaces between the large cutting heads to help comminute the excavated material missed by the large cutter heads. For large machines such as envisioned for the present invention, smaller concentric cutter heads 1725 maybe mounted coaxially with the large cutter heads. These smaller concentric heads 1725 may be rotated counter to the direction of the large coaxial heads as shown to assist in preventing excavated material from sticking near the center of the primary cutter heads. The three large cutting heads may be rotated in opposite directions, as shown, to reduce the roll tendency of the machine 1720. The preferred cross-section is rectangular with overall dimensions in the range of approximately 7.5 to 30 meters wide by approximately 7.5 to 20 meters high. If circular cutting heads are used, the preferred number of heads that comprise the front end is in the range of about 2 to 12.

An identified problem of excavating oil sand is mechanical cutter wear due to the abrasive nature of the quartz sand grains. Another identified problem is the difficulty in handling oil sand material because it tends to become very sticky with working and reworking. Working the oil sand material tends to heat it which causes the bitumen to become more fluid (less viscous), turning it from a solid or semi-solid bituminous substance to very viscous heavy oil. In excavating sandstone or sandy material, TBMs often employ a slurry shield or mixed slurry shield type of cutting head to assist with stabilization of the excavation face. To implement this technique, water is injected into the volume immediately ahead of the cutting head to create a slurry of the excavated material. The slurry so formed is often kept at a slightly higher pressure so as to prevent voids and cavitation from developing so that the material will flow through openings in the cutter head and into the materials handling system. The method can be extended in unconsolidated and soft rock media by using high pressure water jets to excavate the material. Often, the water jets perform the primary excavation and mechanical cutter elements are included to provide backup excavation of any material not fully broken by the action of the water jets. A slurry shield front-end would overcome the two excavation problems described above. First, the formation of a slurry will substantially reduce cutter head wear. Additionally, if water jets are used for the primary excavation, any mechanical cutter heads will be subjected to even less wear from the abrasive action of sand grains. The formation of a slurry by the addition of ambient temperature water ahead of the TBM cutter head also controls the temperature of the excavated material by (1) diluting the material with a heat sink material and (2) by substantially reducing mechanical working of the material. The excavated oil sand material thus may tend to remain as semi-solid substance and not be transformed into a sticky, highly viscous material that will clog machinery or adhere to surfaces of the material handling system. Figure 7a shows a schematic side view of a cutter head assembly comprised of both mechanical cutter elements and water jet cutter elements. The cutter 1800 head contains a number of mechanical cutters 1801 and water jet cutters 1802. The water jet cutters 1802 are used for primary excavation of the oil sand material 1803 and also provide the water to form a slurry 1804 in the volume 1805 between the cutter head 1800 and the forward shield 1806. The slurry 1804 is transported through the cutter head 1800 into a pipeline 1807 which feeds the slurry 1804 into a primary crusher 1807. Figure 7b illustrates a closed cutter head assembly 1820 also using both water jets 1821 and mechanical cutters 1822 for excavating the material and forming a slurry. The isometric view 1823 shows the water jets and mechanical cutters arrayed on a rotary cutter head 1824. Mining Machine Mover

In a mining operation such as would be carried out using the present invention, a large mining machine must enter and exit a portal in the face of the ore body. In addition, the mining machine may require overhaul after each mining drive. Thus, it is necessary to develop a mining machine mover that can ( 1 ) move the mining machine into position at the entrance portal to begin a mining drive, (2) remove the mining machine as it reaches the exit portal at the end of its mining drive, and (3) move the mining machine to a maintenance facility where the mining machine can be overhauled and refurbished before being positioned for the next mining drive. Figure 8 shows an isometric schematic view of a machine that can lift and turn a large mining machine of the present invention. The large mover 2201 would acquire a mining machine, such as a tunnel boring machine 2202 that had exited a portal from a mining drive. The mover 2201 would hold the mining machine 2202 for example using a series of slings 2203. The mover 2201 would move, for example, by utilizing tracks 2204 to move the mining machine 2201 out from an exit portal, move it into a maintenance facility for overhaul, and then move it into position in front of an entrance portal for the next mining pass. The mover 2201 an be fabricated from, for example, structural steel members 2205 and powered by any of a number of means such as compressed air, hydraulic, electric or internal combustion engines.

Internal Processes

In the present invention, the large shields provide opportunity for many processes, in addition to excavating and transporting out ore, to be carried out within the mining machine. Figure 9 presents a flow chart of the oil sands material as it passes through the mining machine for the case where the bitumen is separated from the oil sands in an external processing facility. Oil sands material 2301 enters by the action of the cutter heads. The excavation maybe carried out by forming a slurry at the working face in which case a slurry suitable for hydrotransporting may already be formed. The excavated material is then fed into a primary crusher 2302 where any large fragments are broken down. The oil sands material is then fed to an apparatus where water and other chemicals, if necessary, are combined to form a final hydrotransportable slurry 2303. For example, caustic maybe added to speed up the separation process as is done in the Clark process. Since bitumen separation involves an interplay between mechanical agitation, slurry temperature and slurry PH, chemicals other than caustic may prove cost-effective. The slurry is then hydrotransported 2304 out the access tunnel to an external bitumen separation facility where the bitumen is recovered. The bitumen extraction facility may be located outside the portal or at a substantial distance from the portal. Outside of the scope of the present invention, the bitumen is then sent to a refinery where it is converted into crude oil 2305, the final product. Sand, mud and shale material remaining after the bitumen separation process is hydrotransported 2306 as needed back to the machine via the access tunnel. The returning slurry is fed to an apparatus 2307 where the bulk of the water is removed from the material and appropriate binder and stabilizing agents are added. The resultant material or spoil is then injected 2308 into the volume behind the advancing machine.

Figure 10 shows a flow chart of the oil sands material as it passes through the mining machine for the case where bitumen or heavy oil is separated from the oil sands inside the mining machine. Oil sands material 2401 enters by the action of the cutter heads. The excavation may be carried out by forming a slurry at the working face in which case a slurry suitable for hydrotransporting may already be formed. The material is fed into a primary crusher 2402 where any large fragments are broken down. The oil sands material is then fed to an apparatus where the bitumen is separated from the oil sands 2403. The separated bitumen is then sent to an apparatus in which water and other chemicals, if needed, are combined to form a slurry 2404. The slurry is then hydrotransported 2405 out the access tunnel to an external refinery where it is converted into crude oil 2406, the final product. Back in the machine, the sand, mud and shale material remaining after the bitumen separation process is then fed to an apparatus 2407 where appropriate binder and stabilizing agents are added. The resultant backfill material or spoil is then injected 2408 into the volume behind the advancing machine. Some of the bitumen is removed before the bulk of the bitumen is formed into a slurry and is fed 2409 into a compact asphalt cement plant inside the machine. Additional materials such as binders and crushed rock are brought in from the outside via the access tunnel and fed 2410 into the asphalt cement plant. The materials are processed in the asphalt cement plant 2411 to form part or all of the tunnel liner segments that will be installed as the access tunnel is extended behind the advancing machine. The present invention is extended to include an internal materials processing system that is completely isolated from the machine personnel areas. The crew area can be constructed as a self-contained pressure-resistant volume. Normally the crew area can be open to the access tunnel and remain at atmospheric pressure. In the case of an emergency, however, the crew area can be closed off and operated using a supply fresh air until the emergency conditions are corrected. In the present invention, the emissions from the excavated ore and the mining machine are all contained and routed into the isolated ore transportation system and not released into the atmosphere. Thus the present invention has the potential to contain and dispose of significant methane, carbon monoxide, carbon dioxide and other toxic gases. Further, much of the excess heat generated in the mining machine of the present invention is used to help separate bitumen from the oil sand, further reducing the amount of emissions from the mining, hydrotransport and bitumen separation processes. The present invention therefore can significantly reduce the total emissions associated with the large scale oil sands mining process. Figure 11 shows a side schematic view of a TBM mining machine configuration illustrating the volumes occupied by both outgoing oil sand or bitumen slurry and incoming tailings slurry and other features. The slurry 2600 is formed in the volume 2601 between the cutter head 2602 and the forward portion of the main shield 2603 either by water inj ected into the volume 2601 or by water from the water jet cutters 2604 or from both water jet cutters 2604 and other water injection ports. The slurry 2600 passes through the cutter head 2602, down a pipeline 2605 to a primary crusher 2606, down a pipeline 2607, through a flow monitoring station 2608 and into a processing/switching apparatus 2609 and out a hydrotransport pipeline 2610. A return hydrotransport pipeline 2611 contains a slurry of processed material which is fed into the processing/switching apparatus 2609 where it is de- watered and prepared for injection as backfill into the volume 2612 behind the advancing machme. The processing/switching apparatus 2609 contains an internal apparatus that includes but is not limited to a de- watering apparatus for de- watering the returning processed sands; an internal apparatus for preparing the de-watered sand for injection as backfill; an internal apparatus for separating bitumen from oil sand; and an internal apparatus for diverting the slurry from the primary crusher directly to the de-watering apparatus for de- watering the returning processed sands. The oil sands deposits can be highly variable in ore grade both through the thickness of the deposit and over the areal extent of the deposit. It is also possible to encounter barren water-saturated sands or sands containing a significant fraction of shale, clay and /or mudstone stringers. An extension of the present invention is the addition of an apparatus 2608 to determine the approximate grade of the ore after it passes out of the primary crusher of the mining machine. If the grade of the ore is too low for transporting to the portal, then the slurried ore can be directed to a de-watering plant contained in apparatus 2609 in the machine and inj ected into the volume 2612 behind the advancing machine. In the case where the machine contains a bitumen separation plant in apparatus 2609, the low grade ore or barren material can be diverted to the de- watering plant in the machine and inj ected into the volume 2609 behind the advancing machine.

If the excavated ore is in the form of a slurry, it can be passed through an apparatus 2608 where various diagnostics may be used to determine the average grade of the ore. The ore grade is usually expressed as a percent by mass of bitumen in the oil sand. Typical acceptable ore grades for oil sand is about 6% to 9% by mass bitumen (lean); 10% to 11% (average) and 12% to 15% (rich). A typical oil sand slurry is comprised of water (about 25% to 50% by mass) with the rest being oil sand. Typical slurry flow velocities are in the range of about 2 to 5 meters per second.

The slurry flowing through a diagnostic pipeline section 2608 involves the material to be diagnosed flowing past the diagnostics. This is basically the reverse situation as in conventional well logging where a diagnostic sonde is pulled up through the material to be measured. The relative motions, however, are the same. Thus, conventional well-logging diagnostics can be applied to determine the water/hydrocarbon ratio of the slurry. For example, induction, resistivity, acoustic, density, neutron and nuclear magnetic resonance (NMR) diagnostics can be used to provide the data required to solve Archies equation in the same way as done in conventional well logging practice.

The pressurized chamber 2620 is at a pressure slightly higher than ambient formation pressure in order to exclude unwanted vapors and fluids. The excavated material is brought into the machine by the mechanical action of devices such as for example, a screw auger or directly as a slurry if the machine 2614 is operated in a slurry or earth pressure balance mode. The formation pressures can typically range from atmospheric pressure to pressures up to about 20 or more atmospheres. The pressure in the pressurized chamber 2620 is preferably about 0.1 to 3 atmospheres higher than formation pressure. The pressure in the areas 2621 where operators and personnel are stationed is typically atmospheric since this portion of the machine is connected to the outside world by the trailing access tunnel 2615. It is possible to totally isolate the atmosphere in a TBM mining machine so that it can operate at greater depths and under greater formation pressures. In this mode, a pressure air-lock system 2613 would be required at some point in the trailing access tunnel.

The propulsion motors, hydraulic cylinders and other power generating sources in the machine generate large amounts of excess heat energy which must be removed via the return ventilation, water and/or slurry systems. In general, a TBM type machine produces heat from its propulsion motors, its hydraulic motors and hydraulic cylinders and by the action of mechanical cutter tools, if used. This heat can be utilized for various functions in the present invention. For example, the heat generated from the propulsion motors, hydraulic motors and cylinders and by the action of mechanical cutter tools can be transferred to water or some other appropriate fluid via a heat exchanger apparatus. The water is then available, for example, to be flushed into the area of the cutter head or muck chamber to help form a slurry suitable for hydrotransport. This warm or hot water can also be used to form water jets to help excavate the material and can be used to begin the separation of the bitumen from the sand as the material is being excavated. The waste heat can also be used to elevate the temperature of other materials such as for example a slurry in an internal bitumen separation facility, and the concrete, asphalt, or grout in an internal access tunnel liner extrusion facility and the slurry in a de-watering facility used to de-water a tailings slurry used for backfill. Since the present invention operates underground, the waste heat can be captured and used for other purposes. This is an important energy efficiency advantage over open-pit excavation machines such as shovels and trucks whose waste heat is usually lost in the atmosphere.

Figure 12 shows a preferred embodiment of a heat exchange system to utilize waste heat for heating a slurry at the working face. Waste heat is generated primarily by the action of hydraulic thrust and extension cylinders 2701 and by electric motors 2702 used for various purposes including thrusting and rotating the cutting head. These cylinders and motors may be cooled by a suitable coolant such as water that is pumped through a closed circuit. A pump 2703 pumps coolant into a circuit 2704 which passes through the cylinders 2701 and motors 2702 where it becomes heated. The heated coolant passes through a heat exchanger 2705 where the coolant gives up its excess heat to water in a separate circuit 2706. This water may originate in an outside source 2710 and come in via a pipeline 2709. The water, after passing through the heat exchanger 2705, is injected into the cutting head slurry 2707 (and/or muck chamber and/or water jets and/or bitumen separator and/or internal access tunnel liner and/or de- watering facility). Additional water from another source maybe added to the slurry 2707 to achieve the required slurry conditions. This additional water may also be heated by a separate source (not shown). The slurry formed from water and excavated ore eventually makes its way out of the excavation area via a hydrotransport pipeline 2708.

Propulsion and Steering

As will be appreciated, modern tunnel boring machines can be propelled by a variety of means including thrusting off the tunnel liner erected behind the machine, by soft-ground gripper pads that can be thrust out against the walls of the excavation or by a combination of both methods. These methods allow a forward shield segment to advance relative to a rear shield segment, usually by an array of internal hydraulic cylinders that can extend or retract the segments relative to each other. The diameter of the main shields of most soft ground machines are short compared their length and the above means of propulsion are adequate. hi the present invention, the tunnel liner is much smaller in cross-section than the main shield and the machines tend to be longer relative to their diameters because the machines often contain additional equipment such as, for example, a bitumen separator, a backfill de- watering and inj ection apparatus . The machines envisioned in the present invention can use large area soft-ground grippers for propulsion and can also thrust off the backfill material injected behind the machine. The following describes yet another means of propulsion suitable for a longer machine.

Figure 13 shows a side view of a sequence of machine motions for a large segmented excavating machine that advances by utilizing differential friction as a means of propulsion. In one embodiment, the above method is implemented by a large multi-segmented boring machine apparatus. The segmentation allows the machine to change direction efficiently and allows the machine to follow the meandering oil sands deposits. The segmentation also permits the machine to advance, one segment at a time, by the moving segment thrusting against the combined static friction of the stationary segments. The sequence of motions to advance the segmented machine for the present invention is shown in Figure 13. The initial position of the machine is shown in Figure 13a and the distance through which the machine will advance in one full cycle of movement is shown by 2900. The start of a new advance cycle is shown in Figure 29b. The forward most segment 2901 moves forward, pushed by the hydraulic jack cylinders connecting the forward most segment 2901 with the second segment 2902. The forward most segment 2901 contains the excavating head 2903 and the oil sand is excavated only during the movement 2915 of this forward most segment. Once these cylinders are fully extended, the second segment moves as shown in Figure 13c. The second segment 2902 is advanced by the hydraulic jack cylinders connecting the forward most segment 2901 with the second segment 2902 retracting and the hydraulic j ack cylinders connecting the second segment 2902 with the third segment 2903 simultaneously extending. Each subsequent segment advances in turn in a like manner as shown in Figures 29d through 29h. Finally, as shown in Figure 13i, the aft most segment 2908 moves forward, pulled by the hydraulic jack cylinders connecting the aft most segment 2908 with second to last segment 2907. As the aft most segment 2908 advances, spoil is injected into the volume

2914 behind the machine created by the motion of the aft most segment 2908. The distance

2915 through which the rear end of the machine has advanced in one full cycle of movement is the same as that of the front end shown by 2900. Now the machine has completed one cycle of motion and has advanced a distance 2900 at an average advance rate of the instantaneous advance rate of each segment divided by the number of segments.

Figure 14 shows various alternate means for a TBM mining machine to propel and steer itself. Figure 14a shows a mining machine in a straight, non-turning position. The cutter head 3001, the forward segment 3002, the rear segment 3003, the backfill thrust plate 3004, the backfill tail shield 3005 and the access tunnel tail shield 3005 are all shown in-line along the same axis. The direction of motion of the mining machine is indicated by the arrow 3007. Figure 14b shows the various means by which a mining TBM can turn. The turn can be to the left, to the right, upwards or downwards or any combination thereof. Also any of the means of turning may be applied in any combination to achieve a desired machine positional control and steering. The cutter head 3001 can be articulated with respect to the forward segment 3002 to turn in the direction indicated by arrow 3008. The forward segment 3002 maybe articulated with respect to the rear segment 3003 by, for example, differentially extending its connecting hydraulic cylinders to turn in the direction indicated by arrow 3008. A hydraulically or otherwise actuated drag plate 3009 maybe deployed to cause additional drag which will cause the machine to turn in the direction indicated by arrow 3008. The backfill tail shield 3005 is attached to the rear segment 3003 and so follows the motion of the rear segment 3003. The backfill thrust plate 3004 may be articulated with respect to the rear segment 3003 to turn in the direction indicated by arrow 3008. The access tunnel tail shield 3006 is attached to the backfill thrust plate 3004 and so follows the motion of the backfill thrust plate 3004. The cutter tools (not shown in this view) mounted on the cutter head 3001 may be retracted, extended and oriented by hydraulic actuators to also affect the cutting forces applied to the excavated face. This action can also be used alone or in combination with any of the aforementioned methods to achieve a desired machine positional control and steering. As will be appreciated, drag plates can be located on the right side of the machine to facilitate right turns, on the left side of the machine to facilitate left turns, on the bottom of the machine to facilitate downward turns, and/or on the top of the machine to facilitate upward turns. The drag plate, as its name implies, contacts a wall of the excavation and the resulting frictional force causes the advancement of the machine side on which the drag plate is located to be slower than the opposite side of the machine on which the drag plate is absent or is in the retracted position. The drag plates are hinged to rotate outwardly (the deployed position) and inwardly (the retracted position) or the drag plates may be hydraulically extended and retracted without hinging.

Figure 15 shows a turning sequence that might be used to execute a turn required by one of several possible mining patterns or to avoid barren ground or to navigate around an obstacle. The turn may be executed in any orientation in space (right, left, up, down etcetera). The desired path of excavation is shown by the track 3301. In Figure 15, the mining machine 3302 is shown entering the turn, using several means to cause the cutter head 3303, the forward segment 3304 and the rear segment 3305 to turn in the desired direction. The axis 3306 of the access tunnel tail shield 3307 remains aligned with the desired track 3301. Figure 15b shows the machine 3302 in the middle of the desired turn. Figure 15c shows the machine 3302 near the end of the desired turn. All through the turn, The axis 3306 of the access tunnel tail shield 3307 remains aligned with the desired track 3301. As will be appreciated, the right turn is the mirror image of the left turn.

Access Tunnel Liners An important feature of the present invention is an access tunnel that has a substantially smaller cross-sectional area than the cross-sectional area of the main excavation. There are several means to form the access tunnel, including erecting pre-cast liner segments, extruding the liner or allowing the liner to be formed by consolidated backfill material formed around a temporary form. The preferred embodiment is an extruded liner. As noted above, the access tunnel liner maybe formed by extruding concrete or some other suitable liner material between moveable forms. It then becomes possible to fabricate the forms such that slurry pipelines and other utilities conduits are formed into the liner. This would eliminate the need for separate slurry pipelines and other utilities pipelines and ducts. Figure 16 shows an isometric view of a possible extruded access liner which contains pipelines and other ducts and conduits within the liner material. A possible extruded concrete access liner 3510 which contains an outgoing ore slurry pipeline 3511 and an incoming tailings slurry pipeline 3512 formed into the extruded liner material 3513 within the bottom portion or invert 3514 of the liner 3510. A ventilation duct 3515 is shown formed into the top portion or crown 3516 of the liner 3510. The floor 3517 of the tunnel liner 3510 is preferably flat to allow transport vehicles to pass in and out of the access tunnel.

Alternate Cutter Heads

Figure 17 shows an isometric view of a large multi-segmented excavating machine with two triangular cutter heads that can excavate a roughly rectangular excavation opening and leave a small trailing access tunnel. The machine 4001 is comprised of two Reuleaux triangle cutting heads 4002 which allow the machine to excavate and mine a rectangular cross-section. The machine is shown in a segmented embodiment with the 3^rd segment 4003 from the front fully contracted and the 4^th segment 4004 from the front fully extended. The smaller cross-section trailing access tunnel tail shield 4005 is shown extending from the rear of the advancing machine 4001. The triangular cutting heads have slightly convex sides 4006. Head rotation occurs in two kinds of motion. The first is a pure rotary motion of the head about its own shaft. The second is a circular motion of the entire cutting head and its shaft about an offset center line. This head geometry and eccentric drive system has been used in coal mining to form a square rather than a circular opening in order to extract a greater fraction of the coal in the coal seams. The heads rotate in opposite directions as indicated to substantially reduce the tendency of the machine to roll.

It is also possible to utilize a single backwards tilted rotary excavation head that can excavate a roughly rectangular excavation opening. Such a concept is described in U.S. Patent 4,486,050 which is incorporated herein by reference.

The foregoing discussion of the invention has been presented for purposes of illustration and description, the foregoing is not intended to limit the invention to the form or forms disclosed herein. Although the description of the invention has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the invention, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.

Claims

What is claimed is:

1. An underground mining method, comprising: excavating in situ material in an underground excavation; backfilling at least a portion of the underground excavation to define a trailing passage, wherein a cross-section of the trailing passage is no more than about 30% of a cross- section of the at least a portion of the excavation before backfilling.

2. The method of Claim 1, wherein the backfilling step uses previously excavated material.

3. The method of Claim 1, wherein in the excavating step a movable shield is used to provide ground support during excavating.

4. The method of Claim 1 , wherein the in situ material contains hydrocarbons and the in situ overburden material is sedimentary in origin.

5. The method of Claim 1 , wherein in the backfilling step a form is positioned in the excavation and the backfilling step includes the steps of: contacting the backfill material with a binder; and placing the binder-containing backfill material around the form.

6. The method of Claim 2, wherein in the backfilling step at least one of the following steps occurs: placing a prefabricated liner in the excavation to support the backfill material and define the trailing passage; and forming a liner in the excavation to support the backfill material and define a trailing passage.

7. An underground mining method, comprising: removing in situ material from an excavation face in an underground excavation, the underground excavation having a cross-sectional area near the excavation face and in a direction transverse to a direction of excavation; placing at least one of a liner and form between the excavation face and a surface opening of the underground excavation, the at least one of the liner and form having an outer periphery that is smaller in size than the excavation; and placing at least a portion of the removed material between the at least one of the liner and form and a surface of the excavation.

8. The method of Claim 7, wherein the liner is self-supporting and consolidated and the at least one of a liner and form define a tunnel extending through the at least one of a liner and form, the tunnel having a cross-sectional area in a direction transverse to a direction of excavation that is less than the cross-sectional area of the underground excavation.

9. The method of Claim 8, wherein the tunnel cross-sectional area is no more than about 30% of the underground excavation cross-sectional area.

10. The method of Claim 7, wherein the second placing step includes: forming the removed material into a first slurry; transporting the first slurry out of the excavation; processing the removed material in the first slurry; forming the processed removed material into a second slurry; and transporting the second slurry into the excavation.

11. A continuous underground mining method, comprising: removing material from an underground excavation face using a continuous mining machine, the continuous mining machine being located near the excavation face; and placing at least a portion of the removed material behind the continuous mining machine to form a trailing opening having a cross-sectional area transverse to a direction of excavation that is less than a cross-sectional area of the excavation transverse to the direction of excavation at the location of the continuous mining machine.

12. The method of Claim 11, wherein the removed material is processed within the continuous miner and the at least a portion of the removed material is waste of the processing step.

13. The method of Claim 12, wherein the material includes oil sands and the processing includes separating bitumen in the oil sands from the oil sands.

14. The method of Claim 13 , further comprising displacing the continuous miner in the direction of excavation by pushing against the at least a portion of the material located behind the continuous mining machine.

15. An underground mining method for excavating a hydrocarbon-containing material, comprising: passing a tunneling machine through the in situ hydrocarbon-containing material to form excavated oil sands; and placing a backfill material behind the tunneling machine to form a tunnel of reduced cross-sectional area.

16. The method of Claim 15, wherein the backfill material is at least a portion of the excavated hydrocarbon-containing material.

17. The method of Claim 15, further comprising: comminuting the excavated oil sands with a crusher; forming the comminuted oil sands into a slurry; hydrotransporting the slurry to a processing facility; removing hydrocarbons from the comminuted oil sands forming a hydrocarbon product and a solid waste material; forming the solid waste material into a waste slurry; hydrotransporting the waste slurry to the tunneling machine; and placing the solid waste material in the slurry into the tunnel behind the tunneling machine.

18. The method of Claim 15, further comprising: spraying an excavation face with water during the passing step to form the excavated oil sands into a slurry.

19. A tunneling machine, comprising: one or more mining devices; and a hydrocarbon extraction unit for extracting hydrocarbons from excavated material.

20. The tunneling machine of Claim 19, wherein the hydrocarbon extraction unit includes a bitumen processing chamber.

21. The tunneling machine of Claim 19, wherein the waste heat from an electric or hydraulic device is used to assist in one or more of forming a slurry, separating bitumen from oil sand, de-watering a slurry, and heating a personnel area.

22. The tunneling machine of Claim 19, further comprising: a crusher the excavated material to liberate bitumen from the excavated material.

23. The tunneling machine of Claim 19, further comprising: a solid/liquid separator for dewatering a slurry.

24. A method for excavating and processing bitumen-containing material, comprising: excavating the bitumen-containing material underground; extracting at least a portion of the bitumen from the bitumen-containing material in the underground excavation; and transporting the extracted bitumen to a surface hydrocarbon refinery facility.

25. The method of Claim 24, wherein the excavating is performed using a tunneling machine and further comprising comminuting the bitumen-containing materials in the underground excavation.

26. An underground excavation machine, comprising: a movable body member; and at least one excavation device for excavating material, wherein the movable body member includes at least a first movable shield located at a first end of the body member, the first movable shield extending a first distance from a bulkhead located at or near the first end of the body member, and a second movable shield located at the first end of the body member, the second movable shield extending a second distance from the bulkhead and overlapping the first movable shield.

27. The underground excavation machine of Claim 26, wherein the second distance is longer than the first distance.

28. The underground excavation machme of Claim 26, wherein the first shield is located around at least a portion of a periphery of the second shield.

29. An underground excavation method, comprising: forming a liner surrounded at least substantially by a first movable shield; and placing a backfill material above at least a portion of the first movable shield.

30. The underground excavation method of Claim 29, wherein the forming and placing steps occur at different times.

31. The underground excavation method of Claim 29, wherein the forming and placing steps occur simultaneously.

32. The underground excavation method of Claim 26, wherein at least a portion of the backfill material is covered by a second movable shield.

33. The underground excavation method of Claim 29, further comprising: moving the first movable shield forwardly to cause the liner to contact the backfill material.

34. The underground excavation method of Claim 29, further comprising: supporting a surface of the excavation with a second movable shield located above at least a portion of the first movable shield.