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 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: The proportion of a radioactive material in a moving mass of material is determined with a sensor which derives an output signal proportional to the mass of radioactive material. The output signal is calibrated against known reference values to give a quantitative value of mass. Problems associated with inhomogeneity of material distribution are overcome by averaging the sensed radiation over a time period. Background radiation can be sensed to determine sufficiency of material or it can be shielded from the sensor.

Abstract: A coal/stone mixture transported on a conveyor is investigated by subjecting it to two radiation beams of differing energies. In a preferred embodiment, the higher energy radiation is collimated into a pencil beam and the lower energy radiation into a fan beam. Detector shielding prevents substantial interference of close-to-surface reactions within the detector deriving from the higher energy beam with detection of the lower energy beam.

Abstract: A sensor which is robust for use in an industrial environment. The sensor employs two scintillation crystals to offer a sufficient crystal volume and the crystals are optically coupled through a silicone rubber compound. The compound also allows the crystals to vibrate independently so that they do not shatter. A single photomultiplier detects scintillation occurring in all the crystals.

Abstract: The proportion of a radioactive material in a moving mass of material is determined with a sensor which derives an output signal proportional to the mass of radioactive material. The output signal is calibrated against known reference values to give a quantitative value of mass. The sensor includes a plurality of scintillation crystals. Problems associated with inhomogeneity of material distribution are overcome by averaging the sensed radiation over a time period.

Abstract: A method of steering a mineral mining machine so as to remain in the mineral seam. Natural radiation from rock strata adjacent to the mineral seam is sensed and the machine is steered from the intensity of radiation so that a residual layer of mineral left by the machine which attenuates the radiation has a thickness which is constrained to fall within preselected limits.