| BACK HOME BREAKTHROUGH AT BROKEN HILL SOUTH On April 22, 1963 Broken Hill South Limited made headlines by completing the breakthrough of the longest single drive in the history of Broken Hill mining. The breakthrough linked up their Junction Shaft and their No. 7 Shaft workings by means of a 2 ¾ miles long haulage drive on the 1,480 ft. Level. The completion of this drive marks the final stage of a development programme, commenced in January 1962, to enable ore from the British – Junction leases to be transported underground to No 7 Shaft for hoisting, crushing and milling. The acquisition of the British – Junction leases in January, 1962, presented South Mine management with the problem of stepping up production from these leases and transporting this increased production to the mill. After studies of various schemes had been made, it was decided that the best solution was to gravitate Junction ore to the 1,480 ft. level by means of ore passes connected to the stopes. The ore could then be hauled in a large train to No. 7 Shaft, where existing hoisting and crushing facilities could adequately handle this extra tonnage. The 1,480 ft. level at No 7 Shaft was the most suitable level for the location of this haulage drive. Not only did it extend to within 1 ¼ miles of Junction Shaft, but it lay below most of the known or expected ore in the British – Junction leases. Driving commenced at No. 7 Shaft end on January 15, 1962. At Junction Shaft, where the shaft had to be deepened by 80 feet and the No.14 level plat established, full – scale driving did not start until June 25, 1962. DRIVING METHODS The optimum size of the drive was determined at 9’6” high by 8’ 0” wide. The driving method was based on one that had been successfully used, with the cooperation of the unions concerned, in previously extending the drive by 3,700 feet in 1959 – 60. The driving party was composed of four miners on each of three shifts, who cleaned up, bored and fired a complete end each shift. As skill and work methods improved the length of end increased from 4 feet to 6 feet per shift. A mobile drilling platform was used in boring out the ground; mounted on this platform was an automatic drifter for boring the large diameter holes for the cut. The pattern of large holes varied from two 2 ½ “ diameter holes to one 3” or 4” diameter hole, depending on the nature of the ground. The rest of the round – between 33 and 38 holes – was drilled out with air – leg mounted jack – hammers. The ground was cleaned up with Eimco 21 Loaders, filling into 55 cubic ft Granby trucks at No 7 Shaft end and Eimco 12B Loaders filling into 11 cubic ft. box trucks at Junction Shaft end (the largest size that could be hoisted). The average number of trucks per end was 16 and 60 respectively. Temporary 30 lb. Rail track was laid by the driving party. Permanment air and and water mains, 45 lb. Rails and precast concrete drain were installed by other workmen to within 60 feet of the drive face. The total number of men associated with the two drive faces was 52. This included miners, truckers, platelayers, pipefitters, tradesmen, labourers and mine supervisory and surveying staff. The best fortnight’s advance was 165 feet at No 7 Shaft end, and 135 feet at Junction Shaft. VENTILATION During the operation, fresh air was delivered to the face of the drive from the No 7 Shaft end (an ultimate distance of one mile) using two 15 H.P. fans in series and 281/2”polythene flex, and to three face of the drive from the Junction Shaft end (up to one – third of a mile) using a 71/2 H.P. fan and a 5 H.P. fan in series with a 221/2” polythene flex. Temperatures averaged 75 degrees F. wet bulb. CONTINUE NEXT |