Mineral resource assessment: Compliance between emergy and exergy respecting Odum's hierarchy concept

- Both emergy and exergy are combined to evaluate the environmental impact of mining.
- Specific emergy of mineral reserves is based on chemical and concentration exergy.
- Evaluation of the theoretical minimum emergy for post-mining land restoration.
- 40 main commercially used minerals have been studied.

In this paper, authors suggest to combine the exergoecology and the emergy concept in order to evaluate mineral resources, taking into account their abundance, their chemical and physical properties and the impact of their extraction. The first proposition of this work is to consider that every group of mineral, dispersed in the Earth's crust, is a co-product of the latter. The specific emergies of dispersed minerals are, then, inversely proportional to their abundance. The results comply with the material hierarchy as the specific emergy of a dispersed mineral rise with its scarcity. The second is an emergy evaluation model based on the chemical and concentration exergy of the mineral, its condition in the mine and its abundance. This model permits to assess the decline of mineral reserves and its impact on the ecosystem. The dispersed specific emergy of 42 main commercially used minerals has been calculated. Furthermore, the emergy decrease of some Australian mineral reserves has been studied, as well as the land degradation of US copper mines.