Conservation of Mineral Resources

actual addition alternative amount applied assumed average benefit body calculations capacity capital cent Chapter charges coal companies conservation consideration continue copper costs curve demand depletion deposits discount discussion economic effect efficiency equals estimated example exhaustion extraction fact factors fall FIGURE fixed future given grade greater hand higher increase individual industry interest investment iron larger lead least less level of recovery limits loss lower marginal material maximum means measures mercury metal methods mill mineral mineral resources mining natural necessary objectives obtained operating optimum rate output particular partly plant position possible practice preference present value probably problem production profit rapid rate of recovery ratio recovered reduced relative reserves result rise risk scale selective social society sources stoping submarginal supply tion tonnage tons uncertainties unit usually variable waste whole yield zinc