(Adds detail on output, guidance change for projects)
April 27 (Reuters) - Diversified miner South32 Ltd S32.AX posted a 34% jump in third-quarter metallurgical coal output on Tuesday, thanks to the reintroduction of a form of underground coal mining at its Illawarra project near Sydney.
Output has risen at the Illawarra project since last year after it returned to a three longwall configuration - a form of mining where a long wall of coal is mined in a single slice.
In the three months to March, production of metallurgical coal increased to 1.6 million tonnes (mt), from 1.2 mt a year earlier. That was lower than an RBC Capital Markets estimate of 1.8 mt.
Metallurgical coal sales rose 10% to 1.5 mt.
The Perth-based company's quarterly manganese ore output rose about 8% to 1.4 million wet metric tonnes.
The miner also raised its forecast for full-year output from its South African manganese and Cannington projects by 10% each, drive in part by increased demand.
It kept the full-year metallurgical coal production outlook unchanged at 6.4 mt.
South32, which was spun off from BHP Group BHP.AX in 2015, said it was nearing the sale of its South African energy coal assets, helping it exit the thermal coal sector as concerns grow over global warming.