Application of exergy analysis in recycling streams

Abstract

Materials for recycling always contain a certain degree of contamination. The presence of impurities i.e. contamination in the recycling streams causes a change in the composition of the original materials to recycle. As a result, the quality of materials can be reduced in each successive step of recycling. In addition, the resources of lower quality are produced from the resource flows which had a higher quality in their original form. This kind losses of quality cannot be measured by mass balance, as well as the quality degradation not only can display measurements of mass. For the calculation of all losses caused by recycling contaminations, all further recycling processes required to return the materials back into resource cycles must be included. The method for calculating the exergy content and exergy losses of metal solutions during recovery and recycling is presented in this paper. The losses attributed to recycling, namely the material losses, the contamination losses with other metals, and the consequent need for dilution can be used as indicators of the quality loss of materials and of the efficiency of resource use in product systems. Therefore, exergy is proposed here as a measure of the efficiency of resources use. This paper presents calculations of exergy losses during recycling shown in the case of aluminum waste.