Abstract: A system for controlling microwave heaters in order to efficiently heat frozen ground. The heaters are energized and deenergized by a control unit in response to the temperature sensed a selected distance from a heater. The control unit also deenergizes the heater in response to a temperature sensed in the vicinity of the applicators of the heater in order to protect the heaters from overheating.

Abstract: A method of extraction of metallic sulfides (Matte) from an ore deposit in situ. The contained sulfides are smelted by resistor induced heat creating a matte containing precious metals, including, but not limited to, platinum-group metals and gold and silver (as well as copper, nickel, iron, sulfur, etc). The heavier portion of the bath (matte) settles to the bottom and the slag rises to the top. Further smelting is controlled by positioning of the electrode pairs in the bath, thus regulating heat generation by modulation of the resistance between said electrodes. Placement of the electrodes in cased drill holes strategically placed to intersect and penetrate the ore-bearing horizons results in extraction of the valuable metals as matte. The matte can be recovered either as a liquid, or, after cooling, as a solid.

Abstract: A method for the disintegration of silicon for preparation of semiconductor materials. Polycrystalline silicon in a rod form is subjected to microwave radiation in an oven for a short period of time, whereby the rod-like polycrystalline silicon is dielectrically heated quickly from its inside thereby causing it to be disintegrated.

Abstract: Device for obtaining dust from minerals. The device has an excitation part for mechanical ultrasonic vibrations combined with a chisel. A suction device is provided to collect the dust produced. The device serves in particular to produce dust samples rapidly for quick analysis of minerals in prospecting, in the reconnaissance and evaluation of deposits and in the mining of minerals for the purposes of quality control, monitoring and controlling the mining process.

Abstract: The present invention provides an improved mechanism for positioning the weight relative to the resonant beam in resonantly driven impact systems.

Abstract: Electrohydraulic fracturing of rock and other dense materials is accomplished by coupling a hydraulic medium to the material to be fractured and inducing an explosive electrical discharge in the coupling medium in close proximity to the dense material thus developing an electrohydraulic shock wave in the coupling medium. This shock wave is transmitted into the rock or other dense material as an advancing compressive strain pulse which radiates from the explosive electrical discharge through the dense material until it is reflected by a free surface as a tensile strain pulse. The tensile strain pulse is impedance matched with the dense material to be fractured such that the tensile strain pulse induces in situ fracturing of the dense material. A motor driven generator system which provides alternating current to a control unit which incorporates a transformer and diode controlled bridge rectifier system providing stepped up DC voltage.

Abstract: An apparatus for the charging of rising drillholes (10), preferably large holes of diameter approximately 100 mm or more, with pipecharges (22). The aim is to make it possible to feed charges into the hole in such a way as to fill the hole effectively while making it easy to apply the necessary firing gear (primer and detonator). The charging apparatus comprises a stand (14) capable of being aligned with the mouth (28) of a drillhole by pivoting on a fixed surface (26). The stand includes a lifting means (18) which is provided with a rest (20) capable of travelling towards and away from the drillhole, to carry pipecharges. That part of the stand which is aligned with the drillhole consists of a guide unit (16) which is arranged to guide the pipecharges into the drillhole as the rest travels towards the said drillhole. The pipecharges are retained in place after the lift by retaining means (30).

Abstract: A continuous miner includes a pair of resonant beams for driving a cutting blade rigidly secured to their lower anti-nodes. By mounting the beams so that they can pivot about both upper and lower nodes, the miner may be operated to make either vertical or horizontal cuts. When making vertical cuts, the beams are pivoted upward about their upper nodes to drive the blade in an upward arc in front of the miner, the blade being rearwardly off-set from the center line of the beams to reduce blade drag. To make horizontal cuts, the beams are maintained substantially vertically as the miner is driven forward. The precise angle of the blade relative to the ground may be adjusted to reduce blade drag by tilting the beams an appropriate amount about their lower nodes.

Abstract: The vibrational output of a sonic oscillator is coupled to a compliant member which may comprise a steel stem member. The frequency of the oscillator is adjusted so as to effect resonant standing wave vibration of the compliant member. The resonant vibratory energy is coupled from the compliant member to the pile or other object to be driven by means of a coupler clamp which provides limited bidirectional freedom of motion along the axis of the pile. The coupler clamp further has a guide member which may comprise a partial skirt which controls the angular orientation between the pile and the compliant resonator member. This keeps the sonic energy concentrated along the axis of the pile and prevents significant lateral vibrational modes in the pile. The oscillator resonator member and pile are suspended from an appropriate structure, such as a boom, such that the downward bias weight at the coupler clamp can be controlled. In view of the limited freedom of motion provided in the coupler clamp, i.e.

Abstract: Process and apparatus for enhancing the erosive intensity of a high velocity liquid jet when the jet is impacted against a surface for cutting, cleaning, drilling or otherwise acting on the surface. A preferred method comprises the steps of forming a high velocity liquid jet, oscillating the velocity of the jet at a preferred Strouhal number, and impinging the pulsed jet against a solid surface to be eroded. Typically the liquid jet is pulsed by oscillating the velocity of the jet mechanically or by hydrodynamic and acoustic interactions. The invention may be applied to enhance cavitation erosion in a cavitating liquid jet, or to modulate the velocity of a liquid jet exiting in a gas, causing it to form into discrete slugs, thereby producing an intermittent percussive effect.

Abstract: Previously known ripper apparatus comprise an impacting mechanism for applying impact forces to a ripper tip in an in-line relationship. The high spring rate exhibited by the shank induces high peak internal impact forces, dissipates useful energy, and provides relatively shallow cutting depths. In one aspect, the ripper apparatus (11,11a) of this invention overcomes the above problems by providing an offset relationship between a first line (L.sub.1) of impacting movement of a ripper tip (13) and a second line (L.sub.2) whereat impacting forces are applied to a shank (14,14a) carrying the ripper tip (13) and by further providing a spring mechanism (25,25a) for ensuring that the impacting forces are transmitted from the second line (L.sub.2) to the first line (L.sub.1) directly. In another aspect, the spring mechanism (25,25b) induces an efficient transfer of impact energy from an impacting mechanism (17) to the material being worked by the ripper tip (13), whether the first (L.sub.1) and second (L.sub.

Abstract: A method of vitrifying soil at or below a soil surface location. Two or more conductive electrodes are inserted into the soil for heating of the soil mass between them to a temperature above its melting temperature. Materials in the soil, such as buried waste, can thereby be effectively immobilized.

Abstract: An improved system for cutting pavement into chunks for excavation is disclosed. A plurality of transversely spaced blade elements are provided with forwardly directed cutting edges, the cutting edges on adjacent blades having alternating downward and upward inclinations. The blade elements are attached to a frame so that the elements are reciprocable forwardly and rearwardly. The frame is motivated so that the cutting edges of the blade elements intersect the edge of the pavement. A resonant drive supported by the frame has a vibratory output coupled to the blade elements to drive the blade elements intermittently forwardly and against the pavement. Adjacent cutting elements force the pavement upwardly and downwardly respectively to break the pavement into chunks.

Abstract: A well bore is formed which runs down to an underground region having deposits of mineral material to be mined, by installing a casing or a drill pipe into the ground. A piping assembly is placed in the bore hole through the casing and the mineral material comminuted by means of water jet action or by vibratory action of a portion of the piping thereagainst or by both types of action operating simultaneously. The mineral material is mixed with the water in the bore hole to form a slurry which is removed from the bore hole through the piping by sonic pumping action or by virtue of the slurry rising to the surface as the bore hole fills, with oil floating to the top of the slurry material.

Abstract: A preliminary fracturing method of a rock bed by spouting highly pressurized water into cracks existing in the rock bed to expand these cracks. The preliminary fracturing method of a rock bed comprises drilling a hole in the rock bed by means of a drilling rod having a cutter blade mounted thereto at the leading end thereof, sealing the leading end of the drilling rod by using rock mucks, injecting a high viscosity fluid from the leading end of the drilling rod into the sealed portion of the hole thereby clogging the cracks, and finally spouting a highly pressurized water or highly pressurized high viscosity fluid from the leading end of the drilling rod thereby expanding the cracks. There is also disclosed an apparatus which is adapted to perform the preliminary fracturing of a rock bed.

Abstract: A sonic generator produces a reciprocating force that is transmitted to a tool by a resonant or nonresonant force transmitting member having an output that reciprocates about a neutral position responsive to the force of the sonic generator. A continuous unidirectional force is applied to the sonic generator by a tool carrier. The tool advances intermittently along a work path through a medium responsive to the continuous unidirectional force and the reciprocating force. A gap is held between the neutral output position of the transmitting member and the tool when the tool is unable to advance through the medium responsive to the continuous unidirectional force and the reciprocating force. Specifically, the force of the sonic generator is sufficiently large relative to the unidirectional force to overcome the latter, and to drive the tool holder back away from the tool when the tool is unable to advance along the work path, thereby establishing a protective gap.

Abstract: A surface impact system including a mobile carrier vehicle is disclosed. A beam is provided having a resonant frequency with a pair of nodes spaced from the input and output ends of the beam and anti-nodes at each end and at the center. An oscillator is fixed to the input end of the beam to vibrate the beam at at least near its resonant frequency. The beam is mounted to the carrier vehicle at the node near the input end of the beam. A weight is superimposed over the beam at the node near the output end, and has a bearing surface adapted to bear downwardly against the beam at that node. The weight is coupled to the vehicle to control the vertical position of the weight. A tool depends from the output end of the beam, and strikes the surface on which the vehicle rests at the vibration frequency of the beam as the tool vibrates responsively to vibrations of the beam. The reaction force generated by the tool is substantially absorbed by the weight and not transmitted to the carrier vehicle.

Abstract: A resonant work performing apparatus is disclosed which includes a resonant system which is vibratory in resonance at an unloaded resonant frequency. The resonant system has a vibratory input at a frequency near the resonant frequency, and a vibratory output responsive to vibrations at the input. The resonant system has at least one intermediate node, and the apparatus includes a frame attached to the resonant system substantially at the node. A vibrational force is applied to the input of the resonant system at a given frequency near the unloaded resonant frequency to excite the resonant system to at least near resonance. A sensor is used to determine the frequency of the resonant system. Application of the vibrational force is controlled responsively to the sensor to hold the applied vibrational force at the given frequency.

Abstract: Asphalt roads or the like are repaved by heating and decomposing existing pavement with microwave energy and then remixing and recompacting the constituents of the pavement, the operations being performed at the original location of the old pavement and in some cases without removing the pavement constituents from the roadbed itself. A microwave energy applicator may be traveled along the pavement in front of remixing, grading and compacting equipment or some or all of the equipment may be integrated into a self-propelled vehicle. The vehicle may carry a microwave applicator followed by remixing means such as rotary tillers or the like and grading and compaction devices, and may travel continuously down a road which is reconditioned as the vehicle progresses. Motor generator sets on the vehicle power the microwave sources and the hot exhaust from the motors may be directed to the pavement to supplement the microwave heating and to maintain high temperatures during the additional operations.

Abstract: A method and apparatus for making holes in coal seams in a coal mining system in which hot working gas is employed to impinge on the coal under high pressure and speed in order to disintegrate it and particularly for making inclined or horizontal holes which connect vertical drill holes which lead from the surface to the coal seam and through which the medium for gasifying the coal underground is blown in. The vertical drill holes which lead from the coal seam to the surface are used for blowing out gasification gases which are produced by the operation as well as for delivering the hot working gas. With the method of the invention, a gasification medium of high temperature and pressure is advantageously produced directly at the locations where the disintegrated coal is gasified, the disintegrated coal being formed by a rocket combustion process.

Abstract: A method of producing an underground cavity in a driving shield advance operation comprises, prior to excavation, forming an annular slot corresponding to the contour and wall thickness of the shield ahead of the shield by using hot gas jets to form the slot and to separate a core from the surrounding rock formation, advancing the shield into the annular slot, and breaking out the core under the protection of the shield. The device for producing the underground cavity comprises a tubular drive shield adapted to be advanced into the cavity and having an interior support wall on which is rotatably supported a support member having an arm carrying a gas jet lance. The gas jet lance advantageously includes at least one gas nozzle directed forwardly to form an inwardly extending cavity ahead of the shield, and one or more nozzle discharges directing the gas laterally.

Abstract: An elongated tool is mounted for reciprocal motion on a support frame. A plurality of resonant force transmitting beams each having an input, an output, and at least one resonant node, are supported by the frame so their outputs are spaced apart adjacent to the length of the tool. A sonic generator operating at or near the resonant frequency of the beams is coupled to the beam inputs to produce at the beam outputs resonant vibration about a neutral position. Each beam is pivotally mounted for rotation about its resonant node and such rotation is rigidly limited such that the spacing between the neutral position of the output of each beam and the tool is the same, which synchronizes coupling of force from the beam outputs to the tool. The pivotal node support comprises a closed hollow annular elastic housing and a fluid filling the housing.

Abstract: A vibratory drive system for use in spalling a road surface, cutting rock, etc. Vibratory energy is generated by means of an orbiting mass oscillator, the output of which is rectified by means of a rectifier to provide unidirectional pulses to a cutting tool. In the interests of making the system compact and providing controlled operational parameters, non-resonant operation is employed, optimum drive to the tool being achieved by biasing the oscillator against the tool and by providing a shoulder which fixes the uppermost position of the tool when it is being biased against a load. The tool position and the design of the oscillator are such that the oscillator housing contacts the tool near the mid-down stroke (90.degree.) of the oscillatory vibration cycle, this being the point of highest vibratory velocity and kinetic energy. In this manner, the highest possible delivery of energy to the tool is provided.

Abstract: A method for disintegrating a material comprises acting on the material being disintegrated with shock waves produced upon applying individual electromagnetic field pulses to a current-conducting element arranged in a close proximity to the material being disintegrated. An apparatus for disintegrating a material comprises a unit forming electromagnetic field pulses connected to a current source and arranged in a close proximity to the current-conducting element.

Abstract: A ripping tool positioned below the earth's surface is driven by the output of a vibrating, preferably, resonant, force transmitting beam which has lateral dimensions smaller than those of the ripping tool and is positioned below the earth's surface. The beam is configured to have a single resonant node when restrained from vibrating at such node and is supported so that the single node is above the earth's surface and restrained from vibrating. The output of the beam is enlarged in thickness to form a hammer.

Abstract: A pavement chipping tool uses a sonic oscillator which includes a housing integral with a resonant beam. The oscillator includes a rotating shaft journaled in two sets of bearings with an eccentric weight attached to the shaft between the two sets of bearings and a pair of weights on either end of the shaft beyond the bearings. The eccentric mass of the center weight is equal to the sum of the two outer weights. The bearings have inner races keyed to the shaft.

Abstract: A force transmitting, preferably resonant, beam having a pair of straight divergent legs meeting at a juncture. A work tool is located adjacent to the end of one leg, which is the beam output. A sonic oscillator is coupled to the end of the other leg, which is the beam input. The beam is supported so as to restrain the juncture from vibrating. In one embodiment, the legs form an angle of approximately 90 degrees and the beam is driven at or near its resonant frequency by the oscillator. An integral ear extends from the juncture along a plane that bisects the angle between the legs. The beam is pivotably supported at its juncture and a stop abuts the ear to position the beam output.

Abstract: Asphalt or concrete pavement is removed from a road bed by an elongated cutter blade that extends in a downward and forward direction along a cutting plane to a cutting edge. The cutting plane forms an acute angle of between 45.degree. and 55.degree. with the surface of the pavement. The cutter blade is intermittently driven with a force parallel to the cutting plane in the forward direction while the cutting edge penetrates the pavement to drive the cutter blade incrementally in a forward direction and plane off the pavement in a chisel-like manner. A source of vibrations is connected to one end of plural spaced apart resonant beams. At the other end, the beams drive the cutter blade.

Abstract: A sonic generator produces a reciprocating force that is transmitted to a tool by a resonant or nonresonant force transmitting member having an output that reciprocates about a neutral position responsive to the force of the sonic generator. A continuous unidirectional force is applied to the sonic generator by a tool carrier. The tool advances intermittently along a work path through a medium responsive to the continuous unidirectional force and the reciprocating force. A gap is held between the neutral output position of the transmitting member and the tool when the tool is unable to advance through the medium responsive to the continuous unidirectional force and the reciprocating force. Specifically, the force of the sonic generator is sufficiently large relative to the unidirectional force to overcome the latter, and to drive the tool holder back away from the tool when the tool is unable to advance along the work path, thereby establishing a protective gap.

Abstract: A sonic generator produces a reciprocating force that is transmitted to a tool by a resonant or nonresonant force transmitting member having an output that reciprocates in forward and backward directions about a neutral position responsive to the force of the sonic generator. The tool is located forward of the output of the force transmitting member, and is movable in backward and forward directions along the work path. A changing gap is formed between the tool and the output as the output reciprocates, the gap tending to close and strike the tool as the output reciprocates in a forward direction and tending to open as the output reciprocates in a backward direction. A continuous unidirectional force is applied to the force transmitting member. The tool advances intermittently along the work path through the material being processed responsive to the continuous unidirectional force and the reciprocating force.

Abstract: A bucket wheel type excavator is provided in which a vibrating movement is imparted to the individual cutting components of each bucket on the wheel. Moreover, each such imparting movement to the individual teeth or cutting components is from a single excitation device fixed in the axis of the wheel and driven from a power source coaxially through a hollow shaft for the wheel. The imparting movement is through flexible bars extending from the excitation device to a point adjacent the cutting components wherein the vibrating end of the respective flexible bar is spaced from and intermittently vibrates the cutting component which, in turn, is pivotally mounted.

Abstract: An apparatus and a method for melting block sulphur employ a heating element pivotally mounted on a carriage on a trailer. The heating element is pivoted from a collapsed, transport position to an upright position, and a counterweight force is applied to the carriage to advance the heating element in a direction at least approximately parallel to the ground towards the sulphur.

Abstract: A process for the in-situ recovery of minerals from subsurface deposits comprises forming a gas-tight or self-sealing chamber and injecting into it a solvent which is pressure cycled over a predetermined period of time. This pressure cycling increases the mineral extraction efficiency by improving the dissolution of material contained in blind cracks in the underground formation.

Abstract: A terrazzo grinding machine including a pair of motor driven rotatable co-axially disposed cutter holding spiders, the spiders being interconnected by means of a flexible coupling said spiders including a plurality of clusters of cutting discs supported on the spiders with their axes substantially parallel to the radii of the spiders.

Abstract: Apparatus and method for recovering resources from subterranean rock formations, particularly heat energy, and more particularly geothermal energy. A heat-drill, which has means associated therewith for removing some rock from the earth and forming other rock into shafts, drills into the earth and forms two shafts at the same time. Both shafts communicate with each other and with the surface and are used to circulate a drilling mud which passes through the drill body and carries off the rock being removed. The heating means is shaped in a coil or grid pattern and operates at a temperature well above the melting point of the rock, heating the rock it displaces to well above its melting point, while raising the average temperature of the total rock melted to slightly above its melting point. The drilling mud absorbs heat as it circulates and the absorbed heat is put to any desirable use, particularly by being recovered from the drilling mud by a heat-exchanger on the surface.

Abstract: Staged combustion apparatus is disclosed for generating repetitive explosions. The apparatus includes a first chamber in which a gas under pressure is ignited by an ignition source, such as a spark plug, and a second chamber in which gas under pressure is ignited by gas discharging from the first chamber. The second chamber includes a discharge outlet and a dump valve is provided responsive to the gas pressures in the two chambers for permitting the discharge of gas under pressure from the second chamber when it is ignited. The gas discharge, for example, may be conducted about the tooth of a ripper plow to aid in earth fracture.

Abstract: A method and apparatus are disclosed for drilling gas, oil or geothermal wells in geological formations and for "fracing" the pay zones of such wells to increase recovery, using a laser beam projected into the well bore along a beam guide so as to make available laser energy adequate to melt or vaporize the formation under down-hole conditions. Fluid circulation is established via the beam guide to keep the beam path adequately free of contaminants to permit drilling. A novel orifice window is provided to allow transmitting the high energy beam from the surface into a high-pressure, down-hole environment.

Abstract: Earth boring apparatus is mounted above ground and directs an annulus of high powered laser energy downwardly for boring a cylindrical hole by fusing successive annular regions of the stratum to be penetrated at a power level that shatters and self-ejects successive cores from the hole. A first fluid blast above the hole deflects the ejected core as it exits from the hole. A second fluid blast above the hole ejects fluid to provide adequate fluid at the strata to be penetrated prior to actuation of the laser for promoting a thermal shock capable of shattering and ejecting the core.Optical sensing separately detects the core shattering and the core ejection to control timed actuation of the system components.

Abstract: A method of, and apparatus for, melting block sulfur to avoid contamination of the environment by sulfur dust employ a heating element having a plurality of flow passages formed by pipe sections in a generally planar array, with a steam inlet and a condensate outlet enabling steam to be flowed through the passages. The underside of the heating element has a flow surface adjacent one edge thereof, and a suspension is provided for lowering the heating element onto the sulfur block with the heating element downwardly inclined towards that edge and with the edge projecting beyond the sulfur block so that molten sulfur adhering by surface tension to the flow surface flows beyond the sulfur block and drops into a collecting trough.

Abstract: A self-implanting anchor comprising an elongated body having a first portion comprised of a consumable combustible material extending from a leading end of the body and back along the length of the body, and a second portion defining an anchor for implantation in a compact material and which extends from the first portion of the body and back along the length thereof. The elongated body includes a conduit extending axially therethrough and opening at the leading end of the body for supplying an oxidizer through the conduit to the consumable combustible material at the leading end. In use, the leading end portion is positioned against a surface of the compact material and the combustible material is ignited to melt the compact material in a vicinity of the leading end portion of the elongated body.

Abstract: The method of mining coal entails the use of crude petroleum under high pressure together with elevated temperatures in hydraulic fashion to produce a hybrid oil-coal fuel. A powerful stream of oil is aimed at sections of coal strata to disintegrate the coal. The resultant slurry can be recycled for reuse in the mining operation with provisions being made for screening out the larger coal particles. When the oil-coal slurry reaches the desired consistency, it can be pumped for storage or pipeline delivery to consumers or processing plants.

Abstract: Various methods are shown as to the use of sonic wave generators, or sonic wave generators and modulators as to treating in the fracturing of, the acidizing of or the driving of fluids such as oil, gas or other fluids from subsurface fluid containing strata or formations. The use is shown of gaseous fluids being contained or injected within these subsurface fluid containing strata or formations for the reception of or localizing of these sonic waves of controllable or variable characteristics in this treating of or driving of fluids from these fluid containing subsurface strata or formations. The transporting of heat by these sonic waves into these fluid containing subsurface formations may be a contributing factor in the total effectiveness of these methods of treating or the driving and the subsequent recovery of fluids therefrom.

Abstract: A method of mining rock utilizes a high-intensity electron beam to break the rock. The electron beam is directed onto the surface of the rock, and has sufficient energy either to ablate the rock at the zone of beam impingement and generate an ablation pressure that is sufficiently high to fracture the rock or to expand thermally the rock and generate a dynamic pressure in a lateral direction to fracture the rock. The electron beam is moved along the surface of the rock at a speed in phase with the speed of crack propagation in the rock.

Abstract: A method of earth boring, useful for oil well drilling and the like, employs a high powered laser beam focused and directed by appropriate optics and/or scanning means to a vertically downwardly directed annular pattern. A fluid blast means directed generally into the bore hole is disposed adjacent the beam between the earth and the optics or scanning means. The beam and fluid blast are alternately pulsed and the fluid blast is effective to create thermal shock in the core to shatter it and to deflect material cleared from the hole by the laser beam away from the boring apparatus.

Abstract: A push-type snowplow having a forwardly mounted angled blade reciprocated in a fore-and-aft direction by an oscillating motor drive for thrusting snow aside, the oscillatory impulses of the blade easing the manual effort required for snow removal; a non-jamming easy access reciprocating way system, an adjustable blade, and blade adjustment silencer are provided.

Abstract: A method of extracting metal from an underground ore body. The body is heated by electric induction to a temperature sufficient to break up the metallic ore compound and liquefy the metal. The metal flows into production wells where it is collected and transported to the surface, as by rapid solidification into powder or pellets in a pressurized gas stream. The electric induction is conveniently effected by passing alternating current through a conductor encompassing that portion of the ore body to be heated.

Abstract: Hydraulic mining of tar sands in a formation wherein water is introduced into a plurality of spaced cavities in the bottom of a tar sands formation and above a number of tunnels communicating with respective cavities by openings. In one embodiment of the method, water is sprayed onto exposed tar sands surfaces in the cavity and further creates a moist atmosphere in those regions of the cavity where the water is not directly sprayed on the surfaces. The moist atmosphere can be in the form of suspended water droplets or can be saturated water vapor at a temperature above the ambient temperature of the tar sands or a combination of both. The water on the exposed surfaces penetrates the formation along paths of preferential wetability, causing adjacent portions of the formation to separate and break loose from the formation itself in a direction in which the portions are free to expand.

Abstract: Method of and apparatus for extracting oil from oil shale. An excavating unit is driven by supplying steam to a plurality of steam engines mounted in an annulus between stationary outer and inner casings. A hollow center column and apertured screw vane are mounted for rotation in the inner casing and helical screw sections are provided outwardly of the inner casing at both ends of the apparatus for directing material to and from the inner casing. Steam is supplied to the unit for driving the center column and helical screws, with the steam supplied to the center column emanating through openings in the screw vane mounted in the inner casing for separating the oil from the oil shale by pyrolysis. The oil is withdrawn in the form of a vapor product by means of a vacuum applied to the inner casing for separation and condensation at the surface. Following excavation, the unit can be withdrawn to the surface under its own power.