abstract:Retreat mining is a term used to reference the final phase of an underground mining technique known as room and pillar mining. This involves excavating a room or chamber while leaving behind pillars of material for support.
BHP Billiton Ltd., the world’s largestminingcompany, led a retreatamong raw-material companies, sinking 2.2 percent, as the priceofcopper headed for its largest decline in twoweeks.
Early on, it did not help that her first policy pronouncements were to signal a retreat from Kevin Rudd's mining super profits tax, which made her look weak, and to ditch her predecessor's "Big Australia" policy, which went down well with the tabloids but seemed indicative of a lack of national ambition.