Rio Tinto Mine Pause Unlikely to Have Long-Term Production Impact

0421 GMT - A pause on underground operations at Rio Tinto's Oyu Tolgoi copper mine due to a seismic event is unlikely to have long-term impact on production there, says Jefferies. Yet "a core question that this event generates is: What is the long-term sustainable rate of cave propagation, and does it align with the targeted production rate?" the bank says. The Oyu Tolgoi underground uses block caving, a process that stresses the surrounding rock. Jefferies wonders whether such events could change the way investors value different mining techniques. "For those generalists not frightened from the sector by mining disruptions, we do think that we will start to see further premiums paid for lower-risk mining methods," it says. Rio is down 1.7% in Sydney at 147.09 Australian dollars, amid a broad decline in materials stocks.