Abstract: A rock cutting assembly consists of a rock cutting roller, a shaft on which it is mounted, and a means for varying the mass of the assembly about the drive axis, to vary the balance of the assembly about that axis. Preferably two rollers are mounted on a common drive axis, the axes of the rollers being diametrally opposed and eccentrically displaced by the same distance from the drive axis. The mass-varying means may be a cavity or cavities in the hub or hubs, with means to introduce fluid into and extract it from the cavity or cavities. Alternatively the means may be a weight mounted to permit adjustment to vary the degree of imbalance.

Abstract: A subterranean excavation such as a mine working is cooled by a refrigeration plant having a heat rejection system at an upper station and a heat absorption system in the excavation, the refrigerant medium being ammonia. The system includes a surge drum at the upper station and maybe also at the excavation. Safety measures include the location of the vapor and liquid pipes in a borehole separate from the mine shaft or shafts.

Abstract: A method for the electrical sequential initiation of explosions in which a series of detonators (D1-D11) is located in association with a series of explosive charges spaced from one another and in which a shot initiator 12 is used sequentially to initiate firing of the detonators at selected intervals to detonate the explosive charges, characterized in that each detonator is fired without the provision of a delay between the initiation of firing of the detonator at the shot initiator and the actual commencement of firing of the detonator, further characterized in that the interval between the firing of successive detonators is selected from a range of 5 ms to 40 ms.

Abstract: In the particular embodiments of the invention described herein there is disclosed apparatus for loading particulate material into a train of coupled rail cars. The apparatus includes open topped rail cars which carry a continuous rail track of rails which are attached to the upper edges of the cars, a loading car which carries a ramp which leads from a low level to the track on the rail cars, a bucket loader and perhaps a conveyor for loading a self propelled load distribution vehicle which is adapted to run under its own power on the ramp and the track.

Abstract: A process for constructing the plasmids pDR416 and pDR420 which contain arsenic resistance genes and which are able to replicate in both T. ferroxidans and E. coli comprises preparing a recombinant of pBR325 or the like and a T. ferrooxidans plasmid, forming a deletion plasmid and inserting arsenic resistance genes e.g. from R46 by EcoR1 excision and ligation.

Abstract: A rock cutting assembly which includes a rock cutting roller with the roller being composed of a central hub portion and an annular cutting element which is rotatably mounted on the hub and carries rock cutting formations, means for driving the hub portion of the roller about an axis which is eccentrically displaced from the hub axis, means engaged with the annular cutting element to limit its direction of rotation relatively to that of its hub to one direction only and means for balancing the roller against its eccentricity as the hub is rotated about its drive axis. Preferably the assembly includes a plurality of rock cutting rollers which are rotatable about a common drive axis with the axes of each roller hub being eccentrically displaced by a common distance and in such a direction from the drive axis so that the rollers balance each other as the rollers are rotated about their drive axis.

Abstract: The plasmids pDR401 and pDR412 are disclosed which contain a selectable chloramphenicol resistance gene and which are able to replicate in both T. ferrooxidans and E. coli. A process for constructing the plasmids is also described.

Abstract: In the logging of a grade characteristic of a borehole core, the core is placed in a trough which is caused to move, in step fashion, through an annular detector. For each step the detector measures a characteristic of a notional segment of the core. The measures are corrected to compensate for contributions due to adjacent notional segments. The correction factor is derived by passing a core segment of known characteristics through the detector under controlled conditions.

Abstract: A method of and apparatus for detecting a characteristic in particulate material wherein a stream of the material is caused to move past a plurality of detectors, each of which is responsive to the characteristic, the detectors being so arranged in relation to the material stream that the combined response of the detectors for a given particle possessing the characteristic is substantially independent of the position of the particle relative to the detectors as it passes the detectors.

Abstract: A load distribution vehicle which is adapted to run on a rail track on or over a train of open topped cars for the purpose of loading the cars with particulate material such as mineral ore, broken rock, sand, granular food stuff or the like. The vehicle consists of a bottom discharge hopper which includes a self contained power source for driving the vehicle on its rail track and opening and closing its load discharge doors. The wheels of the vehicle are rotatable on vertical axes and are dish shaped to provide the vehicle with an abnormal transverse movement capacity on its track to enable it to negotiate sharp kinks in its track.

Abstract: A method of eliminating errors in the radiation count of a scintillation detector in radiometric sorting caused by one or more adjacent particles. The spacing between the adjacent particles are determined, and statistically determined calibration factors are applied to the count to compensate for the adjacent particles. The calibration factors are dependent upon the spacings, the counts associated with the adjacent particles, and optionally on the shape, volume, mass and height of the adjacent particles.

Abstract: A method of and apparatus for measuring radio-active emissions from moving radio-active material.Use is made of a radiation detector, a first radiation shield of a first material which shields the detector, and a second radiation shield which is located between at least a portion of the first shield and the detector.The material of the second shield is inherently less contaminated and emits secondary excitation radiation of lower energy than the first material.

Abstract: For measuring the volume of a particle, for example in ore sorting, the particle is caused to move past radiators which illuminate the particle in two transverse directions. Detectors provide measures of the dimensions of the particle in the transverse directions in each of a number of adjacent zones which extend through the particle in its direction of movement. For each zone a volume measurement is derived from the product of the dimensional measurements and the various volume measurements are accumulated to obtain the final volume measurement.The dimensional measurements may be made in each zone in four or more transverse directions, and may be made by means of scanning cameras to obtain a more accurate final volume measurement.

Abstract: A method of determining the grade of a radioactive ore particle wherein a grade measurement of the particle e.g. the ratio of its radioactivity to its mass is corrected by means of predetermined calibration factors which are dependent on one or more of the shape, size, density or mass of the particle.

Abstract: Apparatus for measuring the radio-active emission from a particle including a housing, a plurality of elongated scintillation crystal radiation detectors in the housing with their axes parallel to each other to define between them a passage for the particle to be measured, an elongated photomultiplier attached to each detector with its axis parallel to that of the detector, light transmitting means joining the multipliers to their detectors and means for connecting electronic measuring means to the multipliers.

Abstract: In radiometric sorting a method of compensating for the count recorded by a detector for an ore particle which is displaced from the center line of the detector. The compensation is effected by applying one of a plurality of calibration factors to the detector count. The calibration factors are statistically determined and are dependent on the measured displacement and optionally on at least one of the shape, height, volume or mass of the particle.

Abstract: This invention relates to apparatus for and a method of sorting ore having a radio-active component. The method includes the steps of passing a stream of ore particles through a ring detector to detect ore in the stream having a radio-active emission intensity above a predetermined level and then sorting this ore from the remainder of the ore in the stream. Preferably the invention includes the step of determining the mass of each ore particle and correlating the mass and radio-active emission measurements of the particle to determine its grade.