Abstract: A drive sub for a drilling assembly includes a tubular body configured to receive and releasably engage a drilling tool. The body has inner and outer faces and further has a castellated edge provided on its operative downhole end, which edge defines a plurality of lugs separated from each other by intervening slots. In one aspect the drive sub has a contour profile provided at least partially along a circumference of the castellated edge, wherein the contour profile traverses the castellated edge substantially from the inner face to the outer face. In another aspect the drive sub has a channel provided in each of the lugs, wherein the channel at least partially traverses the lugs and leads from an inlet opening on the castellated edge to an outlet opening on the outer face. The contour profile and/or channel facilitate flow of drilling fluid and cuttings past the lugs during use.

Abstract: There is disclosed a torque transfer apparatus for a mineral drilling tool used in a downhole assembly of a drill string. The drilling tool has a downhole drill bit and one or more uphole drill bits spaced apart from the downhole drill bit, with the torque transfer apparatus being located between them. The apparatus has an axial bore therethrough for fluid flow and comprises first and second members being rotatably joined to each other. The apparatus rotationally couples and transfers torque between the first and second members when a torque difference between torque on the downhole drill bit and torque on the uphole drill bit is below a threshold torque value. The apparatus disengages the rotational coupling while the torque difference exceeds the threshold torque value. The flow rate of drilling fluid flowing through the axial bore is altered when the apparatus engages and disengages the coupling.

Abstract: A drive sub for a drilling assembly includes a tubular body configured to receive and releasably engage a drilling tool. The body has inner and outer faces and further has a castellated edge provided on its operative downhole end, which edge defines a plurality of lugs separated from each other by intervening slots. In one aspect the drive sub has a contour profile provided at least in partially along a circumference of the castellated edge, wherein the contour profile traverses the castellated edge substantially from the inner face to the outer face. In another aspect the drive sub has a channel provided in each of the lugs, wherein the channel at least partially traverses the lugs and leads from an inlet opening on the castellated edge to an outlet opening on the outer face. The contour profile and/or channel facilitate flow of drilling fluid and cuttings past the lugs during use.

Abstract: There is disclosed a torque transfer apparatus for a mineral drilling tool used in a downhole assembly of a drill string. The drilling tool has a downhole drill bit and one or more uphole drill bits spaced apart from the downhole drill bit, with the torque transfer apparatus being located between them. The apparatus has an axial bore therethrough for fluid flow and comprises first and second members being rotatably joined to each other. The apparatus rotationally couples and transfers torque between the first and second members when a torque difference between torque on the downhole drill bit and torque on the uphole drill bit is below a threshold torque value. The apparatus disengages the rotational coupling while the torque difference exceeds the threshold torque value. The flow rate of drilling fluid flowing through the axial bore is altered when the apparatus engages and disengages the coupling.

Abstract: A batch sample preparation apparatus (10) for preparing a geological sample for analysis is described and claimed. The apparatus (10) comprises a dryer (12) having a drying (chamber 52), a sample inlet (20) and at least one sample outlet (22), (24) communicating with the drying chamber (52), to a comminution device (14) in selective fluid communication via valves (26), (28) with the dryer (12) to selectively receive dried sample. The apparatus (10) has a source of fluid (74) introduced at the dryer (12) so that sample material may be transported from the dryer (12) to the comminution device (14) by fluid flow, which fluid flow also extracts the sample material from the comminution device (14) for collection and subsequent analysis.