Emergy-based environmental accounting of one mining system.

Metal production from mineral resources is crucial for economic development. However, most mining activities usually target short-term financial benefits, rather than long-term consideration on ecological sustainability. To better understand the impact of metal production, systematic evaluation methods should be applied to complement current economic accounting tools. Under such a circumstance, this study proposes an emergy-based metal production evaluation framework, taking a life cycle perspective from the formation of mineral deposit to the final production of metal. Ecosystem service loss, CO2 emissions, and emissions' impact are quantified, evaluating the comprehensive performance of a lead and zinc production system in Yunnan Province of China. The results show that minerals contribute significantly to the formation of lead and zinc production; however, emergy received in terms of money substantially undervalues environmental work associated with production. Such a metal production system relies heavily on nonrenewable resources and put enormous pressures on local ecosystems. The beneficiation subsystem generates the highest negative impact per emergy output, followed by the smelting and refining subsystem and the underground mining subsystem. From climate change point of view, producing 1 ton of lead bullion leads to 1.79E+03 kg CO2 eq. Electricity use contributes a dominated share to the total CO2 emission of all subsystems. In addition, lead recycling can greatly reduce the overall CO2 emission, indicating that it is necessary to build up a regional lead collection and recycling system. Finally, several policy suggestions are raised by considering the local realities, aiming to promote sustainable development of this industry.