A fleet of 17 Sandvik hydraulic crawler drill rigs are being used by a Brazelian contractor to drill granite on the massive Jirau hydroelectric project, now underconstruction on the Madeira River in north-western Brazil.
The Jirau project which will have a capacity of 3,450MW generated by 50 turbines, is currently the largest hydroelectric scheme underconstruction in the Americas.
Construction for the project is being undertaken by the consortium ESBR Sustainable Energy of Brazil, under Camargo Correa which is one of Brazil's largest contractors, is undertaking the civil works.
Jirau will have a rockfill dam 35m high and 550m long, flanked by two compacted earthen dikes, one 930m long and the other 1,140m long. The reservoir will cover an area of 258 sq km. Powerhouses on each bank will house the turbines.
Fleet of 17 Sandvik trackdrill rigs include Ranger 600's and 680RP's, Dx600's and seven recently delivered Sandvik Dx700 drill rigs to drill the granite on the riverbank where the dam, spillway and reservoir are being constructed.
All seven Dx700 rigs are fitted with 3 inch standard or 2.5 inch Retrac button bits to generally drill 11m deep holes. In order to offer increased longevity of the 76mm drill bits, regrinding is carried out on site every 22 drilled metres - due to the hardness of the granite with the contractor experiencing rock densities of around 2.65t/m3- ensuring extended bit life of up to 1000 drilled metres.