Total mining costs represent 35% of total plant costs Mine maintenance accounts for less than 30% of the operating- mine cost. With the llSe of continuous miners, mming costs from production materials, maintenance materials, labor, and dilution of ore grade were reduced by approximately 25% from conventional mining. The use of contmuous miners also resulted in improved ground conditions, which in turn meant a reduction in time spent barring down ribs and backs and less spot-bolting off-pattern