Abstract: In a ceramic welding process a composition of matter therefore includes a mixture of refractory particles and oxidizable metal particles wherein the harmonic mean size of the refractory particles is between 300 and 1000 microns, and the size range spread factor of the refractory particles is between 0.4 and 1.1 inclusive.

Abstract: A strata movement indicator includes at least two lengths of suspension wire respectively for remote and near anchors locatable in the same borehole. Each wire carries a cylinder provided with indicator markings, the cylinders being moveable with respect to one another and to a reference tube fixed in the mouth of the borehole. Relative movement of the cylinders with respect to one another and/or to the reference tube indicates the degree of strata movement.

Abstract: A ceramic filter candle arrangement employs a plurality of filter candles held within a tube plate by hold-down weights, each having a flow path, and includes a conduit communicating with the flow path and protruding into the candle filter. A passage is formed between the conduit and the internal wall of the filter candle and leads to at least one exhaust port. In operation, the passage and the exhaust port allow controlled pressure wave leakage during gas pulse cleaning of the filter candle.

Abstract: A protective helmet incorporates a visor retractable therewithin, a fan for providing filtered airflow through a duct within the shell to the visor, and ear defenders mounted substantially within the profile of the shell.

Abstract: A coal extract hydrocracking catalyst having particular utility in a two stage coal extracting process which has a first liquid hydrogen donor solvent oil extraction stage and a second stage comprising catalytic hydrocracking of the extract. Desired levels of hydrocracking and hydrogenation of the extract, with an acceptable level of naphthene formation, are achieved by using on the coal extract hydrocracking catalyst a mixture of a promoted W or Mo catalyst with an unpromoted W or Mo catalyst.

Abstract: A method of steering a double-ended ranging drum type mining machine. The method includes the steps of positioning a first current cut follower at or substantially adjacent the center of the machine. A second previous cut follower is positioned at or substantially adjacent the center of the machine. A tilt measurer determines machine tilt and an estimator estimates mineral thickness and generates algorithms whereby height differences between a current and a previous cut roof can be calculated to control and steer the leading cutting drum; the algorithms are generated in such a manner that cumulative errors along or towards a mine face are minimized or eliminated.

Abstract: A method of steering a double-ended ranging drum mining machine including the steps of positioning a first current cut roof follower at or adjacent the center of the machine and measuring the machine tilt by a second sensor. The coal thickness is estimated by using a third sensor and the data gathered is used in generating algorithms therefrom whereby the height differences between points on the current cut roof can be calculated to control and steer the leading and trailing cutting drums. The algorithms are generated in such a manner that cumulative errors along or towards the face are minimized or eliminated.

Abstract: A two stage coal extracting process has a first liquid hydrogen donor solvent oil extraction stage and a second stage comprising catalytic hydrocracking of the extract. Desired levels of hydrocracking and hydrogenation of the extract, with an acceptable level of napthene formation, are achieved by using on the catalyst a mixture of a promoted W or Mo catalyst with an unpromoted W or Mo catalyst.

Abstract: A method of steering a double-ended ranging drum mining machine includes the steps of positioning two previous cut roof followers spaced apart longitudinally of the machine, measuring machine tilt using a second means, estimating coal thickness using third means and generating algorithms therefrom whereby height differences between points on the current and previous cut roof can be calculated to control and steer the leading and trailing drums the algorithms being generated in such a manner that cumulative errors along or towards the face are minimized or eliminated.

Abstract: A method is provided for testing the activity of a catalyst for a chemical reaction in which naphthalene is reversibly hydrogenated by gaseous hydrogen into tetralin, which avoids the need to pressurize a test vessel with hydrogen, enables simple apparatus to be used and gives good accuracy. Tetralin and catalyst are introduced into a sealed container, the container is heated to a reaction temperature for a predetermined time, and the amount of naphthalene formed by dehydrogenation is determined. The method is applicable to the measurement of catalyst activity for catalysts used in the production by hydrogenation of coal-derived liquids.

Abstract: An aerated cementitious composition is produced by feeding a mixture comprising cement and foaming agent to a mixing chamber open to atmosphere together with a feed of liquid. The ingredients are mixed and the wetted mixture pumped to a desired site, the capacity of pumping being greater than the feed rate of the ingredients into the mixing chamber such that air is drawn into the mixing chamber.

Abstract: Recycled oil solvents for coal extraction have their content of saturated cyclic species reduced by thermal cracking at 470.degree. to 540.degree. C. for a few minutes, restoring their effectiveness as solvents for coal.

Abstract: The trailing drum of a double-ended ranging drum shearer is steered in a seam by producing an algorithm which determines, as a result of information derived from signals from the machine dependant on its tilt, direction and amount of movement along a face being cut. The height of the leading drum is used as a reference from which to determine the optimum position of the trailing drum in order that a constant quality of desired mined material is obtained.

Abstract: In a mineral mining machine of the shearer drum cutter loader type, a system for supplying water at the required pressures includes an intensifier to which in use mine supply water is fed, the pressure being enhanced in the high pressure chambers and the high pressure water being fed to jets on the end of the cutting drum. Water exhausting from the low pressure chambers is fed to the dust and frictional sparking suppression sprays arrayed along the surface of the cutting drum. The method of the invention consists of generating in a simple and effective manner the requisite water pressures utilizing an existing main supply.

Abstract: Geophone detectors are spaced along a long borehole in a mineral seam by pumping grout from a grout tank into a breech assembly and selectively passing the detectors from the breech assembly through gate valves and into a drill string inserted in a borehole. The detectors are connected by a trailing signal cable and an anchor module secures the cable at the far end of the borehole. The detectors can be orientated in the borehole before the grout sets them in position.

Abstract: A transducer is placed in a telescopic strut and connected to a roof cam and a floor cam. The cams are pivoted to a roof support and a constant load is applied to the cams by a gas spring. As convergence takes place a transducer in the telescopic strut records the relative movement between the floor and roof and transmits this as an electrical signal for analysis.

Abstract: Apparatus for extracting and burning methane gas from a landfill refuse site comprises a first venturi to which is fed compressed air. The venturi is connected to a well in the site and acts to draw methane from the well. The methane/air mixture is fed to a second venturi for enrichment with air. The enriched mixture is fed to a burner for combustion.Preferably the compressed air is supplied by a diesel driven compressor.

Abstract: A conveyor belt clamp is made up of a pair of parallel plates which hold a belt between them. Tension is applied by a tensioning bar which is fixed across arms attached to and projecting outwardly from each plate. A hydraulic ram applies the tension and the plates bow centrally towards the belt to give an even distribution of pressure across its width.

Abstract: Geophone detectors are spaced along a long borehole in a mineral seam by pumping grout from a grout tank into a breech assembly and selectively passing the detectors from the breech assembly through gate valves and into a drill string inserted in a borehole. The detectors are connected by a trailing signal cable and an anchor module secures the cable at the far end of the borehole. The detectors can be orientated in the borehole before the grout sets them in position.

Abstract: Briquettes are tested to decrease efflorescence and to improve abrasion resistance and surface appearance, by dipping or spraying the formed briquettes with a solution of polyvinyl alcohol having a concentration greater than 1 part of polyvinyl alcohol to 250 parts of water.