Abstract: A gravity gradiometer is disclosed which has sensor masses in the forms of bars 41 and 43 arranged orthogonal to one another and transducers for providing an output signal indicative of movement of the bars in response to changes in the gravity gradient tensor. The transducers are formed from thin film structure having a first layer forming a fine pitch coil 510 and a second layer forming a coarse pitch coil 511. The layers are separated by an insulating layer. The coarse pitch coil 511 forms a transformer for stepping up the current flowing through the fine pitch coil 510 and the coarse pitch coil 511 supplies current to a SQUID device 367.

Abstract: A gradiometer is disclosed which has a pair of sensor bars 41, 43 supported in housings 45, 47. Transducers 71 are located adjacent the bars 41, 43 to detect movement of the bars in response to the gravity gradient tensor. At least one of the transducers 71 comprises a first coil 510 and a second coil 516 arranged in parallel and a switch 362 for proportioning current between the coils 510 and 516 so as to create a virtual coil at a position D between the coils 510 and 516.

Abstract: A gravity gradiometer is disclosed which comprises a pair of sensor masses 41, 43 arranged in housings 45, 47. Transducers 71 are provided for measuring movement of the sensor masses in response to the gravity gradient tensor. The masses are supported for movement by a flexure web 59 between the mass and a support and a stop comprises a pair of abutment services 554, 555 and 558, 559 defined by a cut 550 prevent movement of the sensor masses 41, 43 beyond the elastic limit of the flexure web 59.

Abstract: A heat switch 570 is disclosed as well as a gradiometer having the heat switch. The heat switch is formed from a non-magnetic material such as a semi-conducting material. The semi-conducting material may be provided by way of a Hall effect device. The heat switches are arranged in the gradiometer on a circuit board 856. The circuit board 850 has conducting strips 856 which are connected to conducting strips on a sensor 71 by bridges 852. The heat switch 570 is connected on the opposite side of the circuit board 850 to the strips 856 and processing circuitry 859. A copper substrate 865 is provided on the same side of the circuit board as the heat switch 570 to conduct heat away from the heat switch 570 when the heat switch is closed.

Abstract: The present invention provides a method of tuning properties of a gravity gradiometer for measuring components of the gravity gradient tensor. The gravity gradiometer comprises a pair of first and second transversely arranged sensor masses that are arranged for movement about an axis and relative to each other in response to a gravity gradient. The gravity gradiometer further comprises first and second capacitors for sensing and influencing the movement of the first and second sensor masses. The method comprising applying a bias voltage to at least one of the capacitors for generating an electrostatic force which acts on one of the sensor masses and thereby influences the movement of that sensor mass.

Abstract: The present invention provides a gravity gradiometer for measuring components of the gravity gradient tensor. The gravity gradiometer comprises at least one sensor mass for movement in response to a gravity gradient. The gravity gradiometer also comprises a pivotal coupling enabling the movement of the at least one sensor mass about an axis. Further, the gravity gradiometer comprises a plurality of capacitors. Each capacitor has first and second capacitor elements positioned opposite each other so that a gap is defined between respective first and second capacitor elements. The capacitors are arranged so that movement of the at least one sensor mass results in a change in the gap between respective first and second capacitor elements. At least one of the capacitor elements has at least two separate capacitor portions arranged so that separate voltages can be applied to the capacitor portions.

Abstract: The present invention provides a gravity gradiometer for measuring components of the gravity gradient tensor. The gravity gradiometer comprises a housing and a gimballed support structure with at least one actuator. The gravity gradiometer further comprises at least one sensor mass arranged for movement in response to a gravity gradient. The gravity gradiometer also comprises a transducer that is arranged so that the movement of the at least one sensor mass relative to a portion of the transducer generates a transducer signal. Further, the gravity gradiometer comprises an electrical feedback loop arranged to direct an electrical signal to the actuator of the external support structure. The gravity gradiometer is arranged so that an influence of an external angular acceleration on the rotation of the housing is reduced by the actuator when the transducer generates a transducer signal effected by the external angular acceleration on the gravity gradiometer.

Abstract: The present invention provides a gravity gradiometer for measuring components of the gravity gradient tensor. The gravity gradiometer comprises at least one sensor mass for movement in response to a gravity gradient and a pivotal coupling enabling the movement of the at least one sensor mass about an axis. Further, the gravity gradiometer comprises a constant charge capacitor that is arranged so that the movement of the at least one sensor mass generates a change in a voltage across the constant charge capacitor.

Abstract: The present invention provides a gravity gradiometer for measuring components of the gravity gradient tensor. The gravity gradiometer comprises at least one sensor mass for movement in response to a gravity gradient and a sensor and actuator unit for generating an electrical signal in response to the movement of the at least one sensor mass and for influencing the movement of the at least one sensor mass. The gravity gradiometer also comprises an electronic circuit for simulating an impedance. The electrical circuit is arranged for amplifying the electrical signal received from the sensor and actuator unit and for directing an actuating signal to the sensor and actuator unit. The electronic circuit comprises a differential amplifiers having first and second amplifier input terminals and an amplifier output terminal and impedances Z1, Z2, Z3, at least one of the impedances have an imaginary impedance component.

Abstract: The present invention provides a gravity gradiometer which comprises at least one sensor mass suspended by a coupling which enables movement of the at least one sensor mass about an axis in response to a gravity gradient. Further, the gravity gradiometer comprises at least one transducer for generating an electrical signal in response to the movement of the at least one sensor mass relative to a component of the transducer and for influencing the movement of the at least one sensor mass. The gravity gradiometer also comprises electrical circuitry for receiving the electrical signal from the at least one transducer and for directing an actuating signal to the at least one transducer so that in use the at least one transducer functions as sensor and actuator.

Abstract: A metallurgical vessel having a cylindrical upper end section and a top section fitted to the upper end of another section to form a top closure of the vessel about a central opening through which to extend a gas injection lance for injecting gas into the vessel. Top section is formed as a two-part domed construction comprising an outer annular panel welded to the vessel top section and an inner annular panel removably fastened to outer panel, both panels being formed with inwardly concave curvature so as to form together the continuously domed top section. The two panels are fastened together by clamping bolts extended through outturned flanges formed on annular flanges standing up from the panels. On release of bolts panel is removable to provide access to the interior of the vessel.

Abstract: A direct smelting plant for producing molten metal from a metalliferous feed material is disclosed. The plant includes a fixed smelting vessel to hold a molten bath of metal and slag and a gas space above the bath. The plant also includes means for supplying solids and gas feed materials to the vessel and for tapping molten material from the vessel. The plant also includes at least two platforms for supporting plant operators at different heights of the vessel. The metal tapping means and the slag tapping means are located so as to be accessible by plant operators on a cast house platform and the end metal tapping means and the end slag tapping means are located to be accessible by plant operators on an end tap platform that is at a lower height than the cast house platform.

Abstract: A molten-bath based direct smelting process and apparatus for producing metals from a ferrous material is disclosed. The process includes injecting feed materials being solid material and carrier gas into a molten bath at a velocity of at least 40 m/s through at least one downwardly extending solids injection lance having a delivery tube of internal diameter of 40–200 mm that is located so that a central axis of an outlet end of the lance is at an angle of 20 to 90 degrees to a horizontal axis. The feed materials injection generates a superficial gas flow of at least 0.04 Nm3/s/m2 within the molten bath at least in part by reactions of injected material in the bath. The gas now causes molten material to be projected upwardly as splashes, droplets and streams and form an expanded molten bath zone, with the gas flow and the upwardly projected molten material causing substantial movement of material within the molten bath and strong mixing of the molten bath.

Abstract: A process and apparatus for supplying solid feed materials for a direct smelting process to solids injection lances of a direct smelting vessel is disclosed. The feed materials supply apparatus includes a supply line (L) for conveying iron-containing material and solid carbonaceous material under pressure to solids injection lances (7), and the supply line includes a main feeder line section (15) and a plurality of branch line sections (17) extending from the main feeder line section. Each branch line section is connected to one solids injection lance for supplying iron-containing material and carbonaceous material to that lance. The apparatus further includes an assembly for dispensing iron-containing material under pressure into the main feeder line section of the supply line and an assembly for dispensing carbonaceous material under pressure into the main feeder line section of the supply line.

Abstract: A molten bath-based direct smelting process for producing ferrous metal from a ferrous feed material is disclosed. The process is characterised by injecting pro-heated air downwardly into metallurgical vessel at an angle of 20 to 90° C. relative to a horizontal axis and at a temperature of 800-1400 ° C. and at a velocity of 200-600 m/s via at least one lance (27) . This step forces molten material in the region of a lower end of the lance away from the lance and forming a “free”space around the lower end of the lance that has a concentration of molten material that is lower than the molten material concentration in the raised bath. The process is further characterised in that the lance is located so that: (i) the lance extends into the vessel a distance that is at least the outer diameter of he lover end of the lance; and (ii) the lower end of the lance is at least 3 times the outer diameter of the lower end of the lance above a quiescent surface of the molt bath.

Abstract: A gas injection lance and an apparatus employing the lance for producing ferrous metal are provided. The lance has an elongated flow duct made of inner and outer concentric carbon steel tubes, a cooling water supply and return, and exterior surface which is designed to hold a frozen layer of slag on the duct, a gas inlet at a rear end of the duct, a tip joining the concentric tubes at the forward end of the duct, a non-metallic or refractory lining for the duct, and swirl-imparting member or members located in the duct for imparting swirl in the gas flow through the forward end of the duct.

Abstract: A hydrometallurgical process for extracting copper and any one or more than one of zinc, silver and gold from a sulphide ore or concentrate is disclosed. The process includes a range of mineral species that contain copper and one or more than one of zinc, silver and gold, which process includes two or more than two leach steps using each liquors of different composition, each leach step selectively leaching one or more than one metal from the minerals. The process also includes separating a solid residue and an exit leach liquor after each leach step, leaching the solid residue produced in each leach step in a successive leach step, and recovering metal from the exit leach liquor produced in each leach step.

Abstract: An injection lance (26) for injecting hot gas into a vessel includes an elongate gas flow duct (31) which receives hot gas from a gas inlet structure (32) and an elongate central tubular structure (33) which extends within gas flow duct (31) from its rear end to its forward end. Adjacent the forward end of duct (31), central structure (33) carries a series of flow directing vanes (34) for imparting swirl to the hot gas flow exiting the duct. The wall of duct (31) downstream from gas inlet (32) is internally water cooled by flow of water through annular passages (43,44). The cooling water also flows through the interior of a duct tip (36) at the forward end of duct (31). The front end of central structure (33) which carries the swirl vanes (34) is internally water cooled by cooling water supplied forwardly through a central water flow passage (52) from a water inlet (53) at the rear of the lance through to a nose (35) of the central structure.

Abstract: A process for upgrading of titaniferous material containing silica, including pretreating the titaniferous material by alkaline leaching to precipitate the silica as an aluminosilicate which is amenable to further leaching. Subsequently, the pretreated titaniferous material is leached under acid conditions, causing the silica to enter solution under conditions such that the silica is not hydrolysed or precipitated as a silicate.

Abstract: A direct smelting process for producing iron and/or ferroalloys is provided, which involves injecting feed materials into a molten bath of molten metal in a metallurgical vessel to form an expanded molten bath zone, and injecting oxygen containing gas, wherein the selection of the number of, and position of, the solids injection and oxygen gas injection lances is such that the expanded molten bath zone includes a raised region around the oxygen gas injection region, and such that splashes, droplets and streams of molten material project upwardly from the raised region, and such that a free space forms around a lower end of the oxygen gas injection lance.