Much less sludge was spilled than first estimated from a dam burst at a Brazilian iron ore mine last November which killed 17 people, co-owner BHP Billiton (BHP.AX)(BLT.L) said on Friday. Satellite assessments showed about 32 million cubic meters of sludge was released into the Rio Doce river, BHP said, citing information from mine operator Samarco, its joint venture with Brazil’s Vale (VALE5.SA). “The amount of tailings released is therefore significantly less than some initial estimates which were in excess of 50 million cubic meters,” BHP said.