Constran, one of Brazil's major construction companies and concrete producers, are using locally produced pneumatic drilling rigs, with equipment supplied by Sandvik Brazil, at one of their largest quarries.
Constran Quarry is one of at least 20 quarries in the foothills surrounding Sao Paulo. The quarry covers an area of 150,000m2 and has an annual production level of 65-70,000m3. Approximately 70% of the gneiss rock produced is used by Constran, either in concrete production or as aggregate for roadbuilding.
Two pneumatic drill rigs are used at Constran Quarry, both units equipped with Sandvik shank adapters to reduce wear, and T38 3m long drilling rods. The 78mm diameter 7514/3876/S45 drill bits are supplied from Sandvik's Sao Paulo factory. Holes to a depth of 15m are drilled with a spacing of 3.5m and a 2.5m burden. On average, 60 holes are drilled before blasting, which takes place twice a week. Constran estimate that 3,000kg of explosives are used for every 60 holes drilled. After blasting, a team of workers with hand-held pneumatic rock drills reduce the size of the boulders before they are loaded on to haulers and transported to the crusher.
The drill rigs work 10h a day, six days a week, using on average 15 rods and 20 bits each week.