Copper cycle in China and its entropy analysis

Copper cycle analysis approaches have been broadly investigated for sustainable development of copper industry in China. There are four stages in the life cycle of copper products, including mining & processing, fabrication & manufacture, use and reclamation. The 2005 copper cycle in China, analyzed by copper-flow diagram of the copper products life cycle with time factor, indicates that the copper ore index and copper scrap index were 0.78 t/t and 0.063 t/t, respectively; and copper resource efficiency was 1.3 t/t. To ascertain the degree of both aggregating and dispersing of the copper in the life cycle of copper products, the substance flow analysis with the index of entropy and the calculating method of entropy was presented. The variation of entropy along copper cycle was calculated based on the analysis of the life cycle of copper products in China in 2005. The entropies at the five nodes along copper cycle were 0.26, 0.046, 0.24, 0.60 and 0.25, respectively. The variation ratio of relative entropy in the whole system was -2.9%, which showed the copper-contained materials were congregated after the whole products life cycle. The same method was also applied to the variation of entropy along copper products life cycle in China in 2002. The discussion was focused on the results of these two years. The values of entropy at the five nodes along copper cycle in 2005 were all lower than those in 2002. The entropy at the five nodes along copper products life cycle in 2005 was extracted through two scenes under different technical indices, including scene one: 0.26, 0.032, 0.23, 0.60 and 0.17, respectively; and scene two: 0.26, 0.023, 0.23, 0.60 and 0.096, respectively. The values of entropy are effectively reduced, especially from the fourth to the fifth node, which is the obsolete copper products reclaiming stage. (C) 2009 Elsevier B.V. All rights reserved.