Abstract: The mobile stope support apparatus comprises a number of individual units (10) which are interconnected by hydraulic cylinders (12). Each of the units (10) has a series of upright, double-acting legs (20). The legs (20) have independent bases of rounded shape and they are pivoted to an overhead canopy (22) which can be raised and lowered by appropriate actuation of the legs. Each unit also has a fore-and-aft hydraulic cylinder (34) which is connected to a common rail (37), the cylinder (34) being pivotable, by the action of a cylinder (36) in an upright plane to raise and lower the rail. By appropriate sequential operation of the various cylinders, the units can be advanced in turn to advance the whole apparatus. In addition, by appropriate operation of the cylinder (36), the front legs (20) can be lifted off the footwall to facilitate movement of the unit over a rough or uneven footwall.

Abstract: Metal values, particularly precious metal values, are recovered from fines on a footwall and in the fissures and cracks therein by passing a solution capable of solubilizing the metal values across the footwall. The metal values are preferably adsorbed on to a suitable support such as activated carbon underground and then the support, having the metal values adsorbed thereon, transported to the surface for further processing.

Abstract: A carbon monoxide gas detector comprises a housing consisting of two enclosures 10 and 12 having ports in the wall thereof to provide a tortuous path for air entering the inner enclosure 12. A gas cell transducer 16 connected to an electrical circuit 18 provides signals indicative of gas concentration. The detector is powered from a remote supply via wires 22 and 26 and provides gas concentration signals via a wire 24 to a remote central station with a fail-safe feature wherein failure of the circuit or the detector will provide signals interpreted as dangerous gas concentrations.