Development of a winged tine to relieve mining-related soil compaction after bauxite mining in Western Australia

Deep ripping, using a conventional chisel-tine to a nominal depth of 1.4 m, was introduced to Alcoa's operations on the Darling Plateau in 1969 following windthrow of a number of trees. Although research into mine floor compaction showed that this ripping depth was sufficient to remove the mining compaction, tillage studies showed that plastic failure around the point of a conventional tine ripping to this depth was actually adding to deep compaction rather than removing it. To improve tillage at depth, wing-like structures were attached to the shank of a conventional chisel-tine directly behind the point. These wings lift and till the soil across a broad front. Wingspans between 0.75 and 1.8 m were tested, and a final design of 1.8-m wingspan adopted for ripping during the 1980s and 1990s. Availability of suitable steels in the late 1990s allowed the winged tines to be fabricated from scratch, enabling the fitting of wear plates to almost completely eliminate shank wear and breakage problems, though these additions have resulted in some loss of tillage efficiency. Modification of the bulldozer ripping box is highly desirable for ripper design to be improved further, particularly to overcome lateral sliding when contour ripping is undertaken on steep slopes. An alternative is to divide the ripping process in two: a pre-rip up and down the slope followed by shallow ripping on contour. A two-step ripping process is now being used at Alcoa's Western Australian bauxite mines.