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~r Production and Distribution at Rietspruit <br />GROUND FROZEN TO HIGHWALL <br />LAST ROW OF. PROFILE BEFORE BLAST <br />HOLES / <br />w J// <br />Z_ <br />J PROFILE AFTER BLAST <br />~ r - - -~ <br />a I I <br />m I 1 <br />w I ^ t----------- _ / <br />a L--'- r I <br />I 62°/° <br />FIG. 14. Section through Blast -parallel Tie-up (0°). <br />Although the parallel pattern gave more throw over, 62Sc <br />vs. 61°,'i. it has been rejected in preference (or the 30° pa[- <br />tern. As can be seen from the sections, the parallel pattern <br />results in freezing of the highwall. This leads to extremely <br />difficult digging conditions on the highwall key cut. Sec- <br />ondar}~ drilling and blasting is necessary at times to bring <br />down the frozen material. <br />The sequencing of tht 30° pattern has the tendency to <br />clean the highwall. ComQaring the patterns shown at the <br />beginning of this sec[ion it can be seen that the energy <br />input near the highwall and presplit line is virtually doubled <br />when applying the 30° pattern as comQared to the parallel <br />patcern. <br />For the above reasons the mine has adopted the 30° <br />pattern. SM ^ <br />E22 <br />Reclamation Foreman P. J. Rousseau, Rietspruit mine. <br />Dragline and Shovel Mechanical Foreman Sakkie <br />Holthuizen, Rietspruit mine. <br />