BHP Billiton Ltd., the world’s biggest mining company, said quarterly iron ore output rose 3 percent on improved rail and plant performance, putting the exporter on target for record annual production.

Output was 61.6 million metric tons in the three months ended Dec. 31, from 60 million tons a year earlier, Melbourne-based BHP said Thursday in a statement. That beat a 61 million tons median estimate among five analysts surveyed by Bloomberg.

Fiscal full-year production guidance for coking coal was lowered to between 41 million and 43 million tons, from an earlier estimated range of 44 million to 46 million tons, on expected lower volumes at the Broadmeadow and Blackwater sites, BHP said.

Work is continuing on a “number of alternatives” aimed at exiting the U.S. onshore oil and gas sector, BHP said. The company also flagged it expects to book a $250 million to $350 million impairment in the first half on redundant conveyor systems at Chile’s Escondida copper mine.

“A strong operating performance in the first half allowed us to capture the benefit of higher prices,” Chief Executive Officer Andrew Mackenzie said. Copper output jumped 20 percent in the quarter on higher volumes at Escondida, while thermal coal output rose 10 percent.

Iron ore production, including third party tons, hit an annualized rate of 284 million tons in the final three months of 2017, above the company’s full-year forecast for output of 275 million to 280 million tons, according to the statement. Rio Tinto Group on Tuesday forecast its full-year cargoes may rise by 3 percent at most.

The steelmaking raw material capped a tumultuous 2017 by surging into a bull market last month, boosting earnings prospects for miners including BHP and Rio.