Abstract: This invention concerns improvements to gravity gradient instruments (GGI) and in particular to the accelerometers that are paired within these instruments. Accelerometers have a proof mass suspended by a spring within a magnetic field. An internal feedback loop provides a signal related to movement of the proof mass back through a reaction coil retaining the proof mass in the magnetic field, to maintain the proof mass stationary. An external feedback loop adjusts the accelerometer scale factor. The internal feedback loop provides second order compensation to the proof mass and the spring stiffness. In a further aspect the invention is a method of matching accelerometer pairs.

Abstract: An apparatus for reducing rotation of an article such as a bird for holding a superconducting quantum interference device for use in airborne transient electromagnetic mineral prospecting. The apparatus includes a support sphere having an inner shell and an outer shell. Liquid is contained between the inner and outer shells and a sphere has openings through which support strings project for locking to an internal point within the sphere. The strings have one end connected to an internal point within the support sphere and another end connected to a spring. The spring includes a damper for damping movement of the spring. Baffles are arranged in the cavity between the inner and outer shells in which the liquid is contained for damping movement of the liquid.

Abstract: Steel with ultrafine grains is produced by altering the transformation from one which normally proceeds with grain boundary nucleation followed by intragranular nucleation at deformation bands and other defects, to one which induces a substantially instantaneous transformation homogeneously over the austenite grain. This is favoured by a reduction or minimisation of grain boundary nucleation, (for example by enlargement of the austenite grain size), prior to or during the transformation. In an embodiment, a partially cooled austenite phase steel is deformed in a single pass at a temperature in the range of 700-950.degree. C. to obtain ferrite grain size of 5 .mu.m or less.

Abstract: This invention is directed to a method and apparatus for thermal homogenization of molten metal in a heath of a electric arc furnace for steel production. The invention addresses the problem of lack of thermal homogenization by providing a lance which directs oxygen gas downwardly towards the surface of the bath and into the molten metal in a direction that diverges away from a direct line to a central region of the hearth through a horizontal divergence angle in the range of 10.degree. to 50.degree. thereby to enhance movement of the molten metal about the hearth and the direction of the gas is inclined downwardly to strike the nominal horizontal plane of the surface of the bath at an inclined angle in the range of 35.degree. to 50.degree. thereby to minimize splashing of the molten metal.

Abstract: A highwall mining system for mining aggregate material from a seam (8) includes a mining device (9) for cutting aggregate material from the seam (8) thereby to form a drive (10) in the seam (8), a conveying device (11) for conveying mined aggregate material from the drive (10), and a circulation device located on or in the region of the mining device (9) for circulating the atmosphere at least at the forward end of the drive (10). The system further includes an inertization device (60, 61, 63, 71) for maintaining the concentration of oxygen in the atmosphere in the drive (10) lower than the concentration of oxygen required for explosion of methane gas and/or dusts and/or other flammable materials in the drive (10).

Abstract: This invention concerns improvements to gravity gradient instruments (GGI) and in particular to the accelerometers that are paired within these instruments. Accelerometers have a proof mass suspended by a spring within a magnetic field. An internal feedback loop provides a signal related to movement of the proof mass back through a reaction coil retaining the proof mass in the magnetic field, to maintain the proof mass stationary. An external feedback loop adjusts the accelerometer scale factor. The internal feedback loop provides second order compensation to the proof mass and the spring stiffness. In a further aspect the invention is a method of matching accelerometer pairs.

Abstract: This invention concerns improvements in the performance of a mobile gravity gradient instrument (GGI). Gravity gradiometers measure one or more components of the gradient of gravity which is expressed as the gradient of a gravity vector, or in other words a tensor. The instrument comprises a first, second, third and fourth accelerometer equally spaced around the circumference of a circle, with their sensitive axes tangential to the circle, and arranged in opposing pairs with the first accelerometer opposite the second, and the third accelerometer opposite the fourth. In use the accelerometers are spun around an axis normal to the circle which passes through its center. A summing amplifier receives the outputs of the accelerometers and combines them in a manner to cancel the common mode output signals and so produces all instrument output. One or more feedback loops extend from the instrument output to one or more of the accelerometers to compensate for errors.

Abstract: A method of extracting a mineral or mineral species comprising contacting the mineral or mineral species with a leachate solution which contains metal or metalloid ions capable of forming soluble fluoro-complexes of high bond strength with fluorine in the mineral or mineral species.

Abstract: A highwall mining system for mining aggregate material from a seam (8) includes a mining device (9) for cutting aggregate material from the seam (8) thereby to form a drive (10) in the seam (8), a conveying device (11) for conveying mined aggregate material from the drive (10), and a circulation device located on or in the region of the mining device (9) for circulating the atmosphere at least at the forward end of the drive (10). The system further includes an inertization device (60, 61, 63, 71) for maintaining the concentration of oxygen in the atmosphere in the drive (10) lower than the concentration of oxygen required for explosion of methane gas and/or dusts and/or other flammable materials in the drive (10).

Abstract: A rock bolt (1) adapted to be anchored in a hole in a rock formation by means of a cement or a chemical resin anchor is disanchored. The rock bolt (1) comprises a core (5) on which is formed a profile for optimising the load transfer and the stiffiess properties of the rock bolt (1), the profile comprising opposed sides (6), with one or both sides (6) comprising at least two sections (9, 11), with a first section (9) being steeper than a second section (11).

Abstract: A high temperature T.sub.c SQUID chip magnetometer has a flux-locked loop circuit including an independent feedback coil having an internal diameter greater than the maximum SQUID chip dimension. The feedback coil is mounted in close co-axial proximity to the SQUID chip to produce a substantially uniform feedback field over the entire area of the SQUID chip to cancel applied fields which penetrate the superconducting material.

Abstract: A highwall mining system for mining aggregate material from a seam includes both a mining device for cutting aggregate material from the seam and thereby forming a drive in the seam and a conveying device for conveying mined aggregate material from the drive. The conveying device is formed of a plurality of modular conveyor units having a mechanism for releasably coupling together the conveyor units. A driving device is used for driving the mining device and the conveyor device into the seam to form the drive. A controlling device is employed to control forward movement of the mining device and the conveying device so that the mining device and the conveying device can move together at a predetermined rate of advance into the seam without there being any uncontrolled forward movement of the mining device and/or the conveying device in response to the incline of the seam and/or during the addition of a new conveyor unit to the conveying device.

Abstract: A large truck with compliant longitudinal frame members is disclosed. The truck has a pair of rear wheel hubs which are independently mounted on the frame members so that the hubs and their tires will rotate about the longitudinal axis of the frame members to accommodate uneven terrain and minimize the forces applied to the individual tires. This also minimizes bending loads on the main frame, rear axles and rear wheel support systems.

Abstract: An apparatus is disclosed which controls the speed of a motor driving a load. A speed controller finds the difference between a command speed value of the motor and a detected speed value of the motor and generates a command current value of the motor on the basis of the difference. A current controller controls current in the motor on the basis of a difference between a command current value received from the speed controller and a detected current value. A torque detector is mounted on the shaft, whereby the motor is connected to the load, for detecting torque acting on the shaft, and an adder adds the detected torque signal detected by the torque detector to the command current value received from the speed controller, the torque detection signal being a correction signal for controlling acceleration torque of the motor.

Abstract: The separation density of a dense media comprising a slurry of magnetite and water in a cyclone for beneficiating coal containing refuse is maintained within predetermined limits by: (a) measuring the total solids in an overflow of the cyclone; (b) comparing the total solids with a predetermined correlation with separation density; and (c) changing the relative proportions of the feed flow of magnetite and water to the cyclone when the separation density as determined by the correlation is outside the predetermined limits.

Abstract: A blast furnace with a blowpipe (12) opening through the furnace wall (11) has apparatus for analysis (20) in a raceway (18) adjacent the blowpipe opening in a bed of the blast furnace. The apparatus includes means (24) arranged in relation to the blast furnace to transmit an optical signal into the raceway and means (30) for monitoring a received signal derived from reflection or scattering of the transmitted optical signal in the raceway. Means (32) is provided to analyse the received signal in relation to the transmitter signal and to thereby obtain a measure of a parameter of the raceway. The method of analysis comprises transmitting an optical signal into the raceway, monitoring a received signal derived from reflection or scattering of the transmitted optical signal in the raceway, and analyzing the received signal in relation to the transmitted signal to obtain a measure of a parameter of the raceway.

Abstract: The casting apparatus includes an electro-slag mould (7) which includes a bath adapted to hold a pool of molten flux and an underlying pool of refined liquid metal and an exit passage extending downwardly from the bath. The casting apparatus further includes electrode carrier (FIG. 2) adapted to feed a consumable electrode (51) of raw metal into the bath and a power supply to pass a heating current from the electrode through the flux pool to melt the electrode. The apparatus further includes a product transporter (FIG. 1) to draw a cast product downwardly from the mould, and a drive (9,11) to effect concerted rotary oscillation about the axis of the product, of the mould, and of the product transporter.

Abstract: The activation of catalysts which include carbonate compounds is brought about by exposing the catalyst to an atmosphere containing hydrogen. The invention is useful for activating Group IIA carbonates, such as strontium carbonate, for use in the oxidative coupling of methane.

Abstract: Processes for converting synthesis gas into hydrocarbons by passing the synthesis gas over a catalyst, and catalysts suitable for use in such processes. The catalysts include cobalt supported on ZSM-5 type zeolites and they also include chromium.

Abstract: A method of operating a diesel or spark ignition engine which includes enriching the combustion air supply with oxygen while simultaneously adjusting the fuel injection or ignition timing of the engine to compensate for advanced combustion caused by an increased oxygen content in the conbustion air. Oxygen producing means such as an oxygen generating membrane can eliminate the requirement for, or significantly reduce the size of, an intercooler which is normally installed between a turbocharger and the air/fuel inlet of an engine. Oxygen enrichment of the combustion air permits combustion of otherwise unsuitable or difficult to combust fuels such as residual or heavy fuel oils, alcohol and alcohol blends, seed oil and blends of light gas oils and residual or heavy fuel oils.