Minister joins Rio Tinto in Warkworth mine appeal THE NSW government has joined Rio Tinto's battle to overturn a court decision to halt the expansion of its Warkworth operation, but the miner has warned it is too late to avoid "significant" job losses at the mine. Darren Yeates, acting managing director of Rio Tinto subsidiary Coal & Allied, yesterday stepped up his fight against what Rio has called an "unprecedented" ruling.