Emergy of Gold Mined at Yanacocha Based on an LCA Model

A Life Cycle Inventory (LCI) was assembled for gold production extending from the formation of gold-ore deposits through the production of semi-refined gold-silver bullion. Inputs traditionally considered in life cycle assessment (LCA) such as energy, materials, and capital were counted along with geologic inputs and labor. Emergy, rather than traditional LCA methods, was used to make inventory cutoffs and to measure environmental impact as total environmental contribution. Uncertainty analysis was performed by characterizing both input flows and unit emergy values with uncertainty values and performing Monte Carlo simulations. A breakdown of emergy requirements for different stages of the process and the uncertainty ranges of parameters and results are presented. The benefits of using LCA software to create and manage LCI inventories and of combining these different accounting frameworks are discussed. The results show that mining is more intense in emergy contribution than the geologic work of deposit formation.