Abstract: Sulfur dioxide is removed from a process gas by passing the process gas through a fragmented permeable mass of particles containing treated oil shale and including alkaline earth oxides. Water in the fragmented mass combines with alkaline earth oxides in the fragmented mass and sulfur dioxide in the process gas with resultant removal of sulfur dioxide from the process gas.

Abstract: A previously mined underground coal deposit is sealed so that the underground void space can be pressurized for production by in situ techniques. Excavated communication passages are sealed by barricades which are further sealed by applying hydrostatic head pressure. Subsidence cracks are sealed by injection of mud slurry with additional sealing effected by maintaining hydrostatic head pressure with a column of the slurry. In situ production wells are drilled into the coal with hermetic seal accomplished in part by cementing a portion of the liner to the well bore and in part by the hydrostatic head pressure of a mud slurry positioned above the cement seal. Coal is ignited and burn patterns are established to cause reasonably uniform subsidence.

Abstract: An underground coal fire is smothered by sealing the overburden for a minimum depth over the coal deposit. Wells are drilled into the fire area and the underground reaction zone is pressurized. Using various combinations of injecting oxidizers and reducing agents the coal deposit is produced in situ to yield a variety of useful products. Wells are cased without cement and with the hermetic seal attained by a column of slurry between the casing and well bore.

Abstract: A combustion zone is advanced through an in situ oil shale retort containing a fragmented permeable mass of oil shale particles by introducing into the retort on the trailing side of the combustion zone: water, at least sufficient fuel to vaporize the water, and sufficient oxygen to oxidize the fuel for vaporizing the water and to form a gaseous combustion zone feed containing water vapor and oxygen. The gaseous combustion zone feed is for introduction into the combustion zone to advance the combustion zone through the fragmented mass of particles and produce combustion gas in the combustion zone.

Abstract: The hydrogen sulfide concentration and total sulfur concentration of a gas of relatively higher hydrogen sulfide and total sulfur concentration are reduced by combining hydrogen sulfide in the gas with oxygen in the presence of a fragmented permeable mass of particles containing oil shale treated to remove organic materials to yield a gas with relatively lower hydrogen sulfide and total sulfur concentration for withdrawal from the fragmented permeable mass.

Abstract: The hydrogen sulfide concentration of a gas is reduced by reacting hydrogen sulfide in the gas with oxygen in the presence of raw oil shale. The ratio of sulfur dioxide to sulfur produced by this reaction depends upon the molar ratio of oxygen to hydrogen sulfide present. Sulfur is the predominant product when hydrogen sulfide is reacted in the presence of oil shale with less than about 1 mole of oxygen for each 2 moles of hydrogen sulfide.

Abstract: Process for the gasification of coal in situ comprising driving shafts or tunnels into a coal seam, injecting air into the bore holes to ignite and burn the coal to raise its temperature ceasing the flow of air when the coal is hot enough to support the endothermic water gas reaction, and injecting steam into the hot coal formation, such steam preferably being preheated by the flue gases taken from the same end of the bore holes where the air was injected, and recovering product gases, including carbon monoxide and hydrogen, and also product oil, exiting the tunnel at the other end of the bore holes. When the temperature of the coal drops during injection of steam to a level which will just permit combustion, the steam flow is stopped, and the cycle is repeated by air injection and flue gas removal at the front end of the bore holes, and through the tunnel connected therewith. This cyclic process is repeated until the entire mass of coal within the area encompassed by the bore holes is exhausted.

Abstract: The hydrogen sulfide concentration of a gas of relatively higher hydrogen sulfide concentration is reduced by combining at a temperature less than about 650.degree. F hydrogen sulfide in the gas with oxygen in the presence of a fragmented permeable mass of particles containing oil shale to yield a gas with relatively lower hydrogen sulfide concentration for withdrawing from the fragmented permeable mass.

Abstract: The locus of a processing zone advancing through a fragmented permeable mass of particles in an in situ oil shale retort in a subterranean formation containing oil shale is determined by monitoring for sound produced in the retort, preferably by monitoring for sound at at least two locations in a plane substantially normal to the direction of advancement of the processing zone. Monitoring can be effected by placing a sound transducer in a well extending through the formation adjacent the retort and/or in the fragmented mass such as in a well extending into the fragmented mass.

Abstract: In a process for retorting oil shale in an situ oil shale retort having a tunnel adjacent the retort, off gas is produced. Leakage of the off gas into the tunnel is prevented by withdrawing off gas from the retort at a rate sufficient to reduce the pressure in the retort adjacent the tunnel to a pressure below the ambient pressure within the tunnel.

Abstract: The invention relates to the hydraulic underground mining of bituminous sands, oil shales and other friable mineral deposits. Accordingly, the invention resides in the provision of a tunnel complex at or near the base of the deposit, in which tunnels are driven parallel one with the other, and spaced a substantial distance apart. An exemplary distance would be in the region of 2,000 feet. Hydraulic excavators are driven outwardly from the sides of the tunnels until the excavator heads are in a position substantially midway between adjacent tunnels. The excavators are arranged in a multiple array at spaced intervals along the tunnels, these intervals being adjusted such that there is interaction during operation, between adjacent excavator heads. The excavators may be positioned in two or more tiers by insertion into the deposit at differing angles from the operating tunnel, such that interaction between excavators is in two dimensions, horizontal and vertical.

Abstract: A method of processing oil shale in which an in situ oil shale retort comprising an elongated cavity containing a fragmented permeable mass of formation particles containing oil shale is formed in a subterranean formation containing oil shale to recover liquid and gaseous products. Access to the cavity is by a drift or conduit at each end of the cavity and through a drift at an intermediate position. A processing zone is established in the fragmented mass at one end of the cavity and processing gas is introduced at that end of the retort and heating of the fragmented mass of formation particles is conducted from that end towards the other end. Initially, off gas is withdrawn at the intermediate drift. When the processing zone passes the intermediate drift, processing gas is introduced through the intermediate drift and off gas including gaseous products is withdrawn by way of the drift at the other end.

Abstract: The present invention is directed to a method of in situ coal gasification for providing the product gas with an enriched concentration of carbon monoxide. The method is practiced by establishing a pair of combustion zones in spaced-apart boreholes within a subterranean coal bed and then cyclically terminating the combustion in the first of the two zones to establish a forward burn in the coal bed so that while an exothermic reaction is occurring in the second combustion zone to provide CO.sub.2 -laden product gas, an endothermic CO-forming reaction is occurring in the first combustion zone between the CO.sub.2 -laden gas percolating thereinto and the hot carbon in the wall defining the first combustion zone to increase the concentration of CO in the product gas. When the endothermic reaction slows to a selected activity the roles of the combustion zones are reversed by re-establishing an exothermic combustion reaction in the first zone and terminating the combustion in the second zone.

Abstract: An apparatus and method utilizes a plasma arc torch as a heat source for recovering useful fuel products from in situ deposits of coal, tar sands, oil shale, and the like. When applied to a coal deposit, the plasma torch is lowered in a shaft into the deposit and serves as a means for supplying heat to the coal and thereby stripping off the volatiles. The fixed carbon is gasified by reaction with steam that is sprayed into the devolatilized area and product gases are recovered through the shaft.When applied to tar sands and oil shale, the torch is lowered in a shaft into the deposit and serves as a heat source to allow the entrapped oil in the tar sand or the kerogen in the oil shale to flow to a reservoir for collection. When economically justified, the carbonaceous matter in the tar sands or oil shale deposits may be partially or completely pyrolyzed and recovered as gaseous fuel products.

Abstract: A method of processing oil shale to recover liquid or gaseous products which comprises constructing longitudinally sloping trenches excavated in a mineral deposit which is relatively impermeable in relation to the crushed oil shale, placing the crushed shale into the sloping trenches and covering same with a compacted layer of clay or other relatively impermeable and essentially inorganic minerals and thereafter igniting the oil shale at the upper end of the trench. Air is introduced at points along the upper end of the trenches and as the retorting zone moves longitudinally downward in the sloping trenches the liquid and gaseous materials are withdrawn at points located at the lower end of the trenches.

Abstract: This application discloses a process for accomplishing in situ retorting of coal, or a similar hydrocarbon by constructing a substantially impervious retorting area, and then fragmenting the coal to provide a substantially homogeneous, porous mass. After pyrolysis due to the introduction of oxygen-containing gas at one portion and withdrawal of oil and gas at another portion, the direction of gas flow is reversed to convert the char into a relatively high B.T.U. gas product.

Abstract: An in situ oil shape retort is provided in a subterranean oil shale formation. An inlet gas access is provided to an end of the in situ retort through which gas is supplied to initiate and advance a retorting zone through the in situ retort for converting kerogen in the oil shale to liquid and gaseous products. A zone of fragmented oil shale fills the in situ retort and extends from the inlet gas access means to the product recovery end of the in situ oil shale retort. The zone of fragmented oil shale has a length from the inlet gas access means to the product recovery end of the in situ retort in the range of from about two to five times the width of the zone of fragmented oil shale and an average void fraction of about 10 to 25 percent of the volume of the zone of fragmented oil shale. In a preferred embodiment the in situ retort is vertical with a height between two and three times its width and the average void fraction is about 15%.

Abstract: An underground in situ oil shale retort, having predetermined boundaries, contains a bed of fragmented oil shale particles having an appreciable void volume distributed therethrough. Air passed through this bed of fragmented oil shale supports combustion of some of the carbonaceous material in the oil shale and provides heat for retorting oil therefrom. A number of such retorts may be formed in an area and pillars are left to support the overburden. Pillars forming walls between adjacent retorts also prevent gas leakage. Oil recovery from intact oil shale pillars is enhanced by fracturing the pillars as well as fragmenting the shale in the retort. The pillars are fractured by hydraulic fracturing, electrical fracturing, liquid explosive fissuring, or the like. The fractures are propagated from access holes in the vicinity of the pillars, typically between similar holes adjacent the next retort volume when the pillars are between retorts.

Abstract: A subterranean deposit containing oil shale is prepared for in situ retorting by initially excavating a plurality of vertically spaced apart voids of similar horizontal cross section located one above another within the deposit. A zone of unfragmented deposit temporarily left between each adjacent pair of voids has a thickness greater than the smallest lateral dimension of the voids above and below it. Explosive placed in a lower portion of the unfragmented zone is detonated to expand the lower portion of the unfragmented zone into the lower void, leaving the upper portion of the zone intact and creating a space free of fragmented particles below it. Thereafter, the remaining portion of the unfragmented zone is explosively expanded into the open space below it and into the upper void, forming a subterranean room filled with a fragmented mass of particles having a void volume substantially equal to the total initial volume of the voids.

Abstract: An in situ oil shale retort is formed in a subterranean oil shale deposit by excavating a columnar void having a vertically extending free face, drilling blasting holes adjacent to the columnar void and parallel to the free face, loading the blasting holes with explosive, and detonating the explosive in a single round to expand the shale adjacent to the columnar void toward the free face in layers severed in a sequence progressing away from the free face and to fill with fragmented oil shale the columnar void and the space in the in situ retort originally occupied by the expanded shale prior to the expansion. A room having a horizontal floor plan that coincides approximately, with the horizontal cross section of the retort to be formed is excavated so as to intersect the columnar void. The blasting holes are drilled and loaded with explosive from the room. The room can lie above the columnar void, below the columnar void, or intermediate the ends of the columnar void.

Abstract: An in situ oil shale retort is formed in a subterranean oil shale deposit by excavating one or more slot-shaped columnar voids each having a pair of vertically extending, planar free faces, drilling blasting holes adjacent to the columnar void and parallel to the free faces, loading the blasting holes with explosive, and detonating the explosive in a single round to expand the shale adjacent to the columnar void one directionally toward each free face in one or more planar layers severed in a sequence progressing away from each free face and to fill with fragmented oil shale the columnar void and the space in the in situ retort originally occupied by the expanded shale prior to the expansion. The pair of free faces extend across the entire width (or length) of the retort being formed. A room having a horizontal floor plan that coincides approximately, with the horizontal cross section of the retort to be formed is excavated so as to intersect the columnar void.

Abstract: A subterranean deposit containing oil shale is prepared for in situ retorting by initially excavating a plurality of vertically spaced apart voids of similar horizontal cross section located one above another within the deposit. A plurality of vertically spaced apart zones of unfragmented deposit are temporarily left between the voids, each unfragmented zone having a thickness of less than about 190 percent of the smallest lateral dimension of the voids above and below it. Explosive placed in each of the unfragmented zones is detonated, preferably in a single round to expand each unfragmented zone into the voids on either side of it and form a subterranean room containing a fragmented mass of particles having a void volume equal to the void violume of the initial voids. Retorting of the expanded mass is then carried out to recover shale oil from the oil shale.

Abstract: A technique is described for reducing the content of oil and water in the flue gas recovered from the bottom of an underground in situ oil shale retort. In such a retort air is passed downwardly to sustain a combustion zone for retorting oil which is recovered at the bottom. Flue gas recovered from the bottom of the retort contains water vapor and oil and water aerosols. These are removed from the flue gas by passing it a substantial distance upwardly through cool overburden so that the flue gas is cooled below its dew point so that water condenses in the vertical conduit and aerosols are dropped out on the walls. The oil and water are recovered at the bottom of the conduit and stored in an underground sump.

Abstract: An in situ oil shale retort is ignited by directing a combustible inlet gas mixture into an ignition zone extending across the top of the in situ retort and igniting the combustible mixture to create a combustion zone in the in situ retort. The ignition zone has a sufficient volume of interconnected open spaces for the movement of inlet gas through the ignition zone with minimal pressure loss, and the in situ retort below the ignition zone has sufficient void volume that inlet gas can be introduced into the ignition zone and moved downwardly through the in situ retort to the bottom. After ignition of the combustible mixture, additional quantities of a combustible mixture are directed into the ignition zone to maintain the combustion zone. Flue gases generated in the combustion zone are moved from the combustion zone toward the bottom of the in situ oil shale retort to establish a retorting zone on the advancing side of the combustion zone.

Abstract: An underground in situ oil shale retort contains a bed of fragmented oil shale particles having an appreciable void volume distributed therethrough. Air or other retorting gas passed through this bed of fragmented oil shale supports combustion of some of the carbonaceous material in the oil shale and provides heat for retorting oil therefrom. A number of such retorts may be formed in an area and pillars are left to support the overburden. Pillars forming walls between adjacent retorts also prevent gas leakage. Oil recovery from intact oil shale pillars between retorts is enhanced by fracturing the pillars as well as fragmenting the shale in the retort. The pillars are fractured by detonating explosives in bore holes in the region between the retort and pillars, preferably a fraction of a second after explosive fragmentation of the oil shale in the retort.

Abstract: An in situ oil shale retort is provided with a retort off gas cooling zone in the in situ retort at the product outlet end of the in situ retort. The kerogen in the in situ retort is converted to liquid and gaseous products by moving a heated gas through a retorting zone in the in situ retort and toward the product outlet end of the in situ retort. The movement of gas through the retorting zone is terminated when the retort off gas moving from the product outlet end of the in situ retort attains a temperature above which the temperature of the retort off gases will deleteriously effect product collection and removal apparatus in a collection zone adjacent to the product outlet end of the in situ retort. A reduced kerogen content of the oil shale in the retort off gas cooling zone as compared with the average kerogen content of oil shale in the in situ retort improves the yield of products from the in situ retort.

Abstract: A process for in situ retorting of oil shale wherein an externally heated gas is circulated through a first retort zone. Surface retorting units comprised of compressors and furnaces are used to start the retorting process and to continue same until the off gas being recovered from the first retort zone reaches a temperature condition which is indicative that adequate heat is available in the retort zone to complete the retorting process without further external heating of the retorting gas. The surface retorting units are then replaced with frontal advance units comprised of low head fans which are capable of circulating the required volume of retorting gas but which require substantially less power to operate than the compressors. Also, when the units are interchanged the off gas from the first retort zone is diverted through a second retort zone to cool the off gas and to preheat the second zone.

Abstract: A method for rubblizing an oil shale deposit that has been formed in alternate horizontal layers of rich and lean shale, including the steps of driving a horizontal tunnel along the lower edge of a rich shale layer of the deposit, sublevel caving by fan drilling and blasting of both rich and lean overlying shale layers at the distal end of the tunnel to rubblize the layers, removing a substantial amount of the accessible rubblized rich shale to permit the overlying rubblized lean shale to drop to tunnel floor level to form a column of lean shale, performing additional sublevel caving of rich and lean shale towards the proximate end of the tunnel, removal of a substantial amount of the additionally rubblized rich shale to allow the overlying rubblized lean shale to drop to tunnel floor level to form another column of rubblized lean shale, similarly performing additional steps of sublevel caving and removal of rich rubble to form additional columns of lean shale rubble in the rich shale rubble in the tunnel, an

Abstract: A method for recovering shale oil and gas from subsurface oil shale deposits in which free space is formed in the shale deposit and relieved blasting toward the free space from first shot holes drilled into the shale from the ground surface fills the free space with rubble. In-situ combustion of the rubblized shale decomposes organic material in the shale to form shale oil and gas, which are conveyed by combustion products through the shot holes to the surface, and leave a weak, easily compressible spent shale. After the in-situ combustion, shale surrounding the spent shale is rubblized by explosives detonated in second shot holes blasting toward the previously retorted zone. The second shot holes, which also are drilled from the surface into the shale, are spaced laterally from the first shot holes. The rubblized shale is then retorted by in-situ combustion. The successive rubblizing and in-situ combustion steps can be repeated to move the combustion operation laterally through the shale deposit.

Abstract: An underground room in substantially undisturbed shale is filled with fragmented oil shale particles for in situ retorting. A comprehensive system is provided for feeding air to the top of the retort and recovering oil and flue gas from the bottom of the retort. The oil is separated from admixed water and both are recovered. Flue gas is withdrawn from the bottom of the retort, scrubbed clean and a portion may be recycled through the retort while another portion is vented or burned in a turbine. Means are also provided for passing scrubbed gas through a second spent shale retort prior to venting, burning or recycle.

Abstract: An in situ oil shale retort is provided with a sealed space at the bottom in which liquids produced in the in situ retort and retort off gases are separated. The separated liquids and retort off gases are removed from the sealed space through a bulkhead provided in an access tunnel leading to the sealed space which can be a portion of the tunnel. A sump is provided in the floor of the access tunnel inside the sealed space for collecting liquids. Trenches extending from the bottom of the in situ retort into the sump are provided for directing liquids from the in situ retort to the sump. The trenches are backfilled with large shale particles to prevent blocking of the trenches when the oil shale in the retort is explosively fragmented. Conduits extending through the bulkhead and into the sealed space are provided for removing liquids from the sump and retort off gases from the sealed space above the liquid level.

Abstract: A technique is provided for igniting one in situ oil shale retort with flue gas from an earlier retort. Towards the end of oil shale retorting the flue gas from an in situ retort has a substantial fuel value so that it can be burned for generating heat. This fuel gas is conveyed to the entrance to a second retort and burned to initiate retorting. Even after retorting of the bed of particles in the first retort is completed, a fuel rich flue gas can be obtained and used for ignition of a subsequent retort. In either case the prior retort has a large bed of hot spent oil shale particles through which air is passed to burn carbonaceous material therein. Hot flue gas from the earlier retort can also be used for preheating.

Abstract: Subterranean mineral deposits, such as oil shale or the like, are prepared for in-situ retorting by selectively mining out an area at the base of the deposit leaving an overlying deposit supported in a suitable manner such as by a plurality of pillars. The overlying deposit is expanded in any suitable manner into the underlying area in a fashion to create a predetermined distribution of permeability from an area of low permeability to an area of high permeability. An inlet is provided at the low permeability area and an outlet at the high permeability area. A suitable medium is introduced into the deposit at the low permeability end for extracting and forcing mineral values from the deposit toward the outlet end for recovery.

Abstract: The invention is directed to a method of in situ extraction of a constituent of a rock formation, e.g., copper deposits or particular petroleum deposits as found in oil shale, and to a method of preparing the rock formation for in situ extraction of the rock constituent. Various embodiments of a side excavating machine are also disclosed for preparing the rock for in-situ extraction of a constituent therefrom. The excavating machine breaks the rock in-situ in a manner to form a narrow, horizontal flow-directing chamber in the rock-filled with fluid-permeable broken rock.

Abstract: The rubble pile in an in situ reactor, which has a low length-to-diameter ratio and limited retorting gas inlets and outlets, has a radial bulk permeability distribution controlled to provide retort working gas flow paths from the inlets to the outlets with substantially even overall flow resistance. Channeling of retort gas along paths of low resistance is therefore avoided. An example of the controlled radial distribution of bulk permeability is a cylindrical, vertical in situ retort having a retort gas inlet and outlet on its longitudinal axis. The bulk permeability of the rubble pile progressively increases from the center to the wall of the reactor. The rubble pile is created by undercutting a carbonaceous deposit and expanding, as by explosives, the unexcavated deposit overlying the undercut.

Abstract: An in situ retorting method and system for recovering hydrocarbons from an oil shale deposit. A retorting zone is formed in the deposit and is comprised of at least two galleries which are separated by a barrier of oil shale thick enough to prevent leakage of gas between galleries. A plurality of rooms are formed within each gallery and are defined by walls of oil shale having substantially less thickness than said barriers. As a gallery is completed, it is sealed and rubblized oil shale within the rooms of said gallery is retorted and the products recovered. Since the barriers between galleries protect workers against gas from a retorting gallery, work can continue on adjoining galleries while said gallery is being retorted.

Abstract: An in situ oil shale retort in which a cavity filled with broken particles of oil shale is formed within the subsurface oil shale formation and air is forced down through the cavity to sustain combustion of the top layer of oil shale particles. The products of combustion are withdrawn through a plurality of transverse exhaust pipes at the bottom of the cavity, the exhaust pipes each being provided with a series of holes along the length of the pipes within the cavity, the holes being graded in size to compensate for the pressure drop along the length of the pipe so as to provide substantially equal volume of gas flow through each of the openings.

Abstract: Method for recovering bitumen from oil or tar sand using jets of hot water and/or steam introduced into the sand via raises connected to underlying spaced aprt tunnels. The jets are arcuately moved horizontally in overlapping patterns to slurry the sand. Caverns are formed by caving the tar sand and removal of the slurry into which the over burden is permitted to cave forming there above a surface depression usable as a tailing pond. Cavities are formed by other jets which connect with the priorly formed cavities so there is a continuous backward movement of interconnecting cavities.

Abstract: There is disclosed a method for the gasification of coal in situ which comprises drilling at least one well or borehole from the earth's surface so that the well or borehole enters the coalbed or seam horizontally and intersects the coalbed in a direction normal to its major natural fracture system, initiating burning of the coal with the introduction of a combustion-supporting gas such as air to convert the coal in situ to a heating gas of relatively high calorific value and recovering the gas. In a further embodiment the recovered gas may be used to drive one or more generators for the production of electricity.

Abstract: A technique is provided for cooling the flue gas or off gas from the bottom of an in situ oil shale retort. The gas is collected in a conduit that has a vertical portion through which the gas flows upwardly. It is then withdrawn from the retort through a gas tight bulkhead. Water is sparged downwardly through the vertical portion of the conduit for cooling and cleaning the gas. Means are provided for draining the sparged water into a sump at the bottom of the retort wherein oil and water are collected. Water and oil are separated and the water may be recycled for additional cooling.