Exergy concept and its implementation in the recycling of metals

Abstract

Modern industrial product design implies presence of many different materials. Consequently, in the recycling process, shredding and separation procedures are applied. However, all materials cannot be completely separated; therefore, there is a contamination in the recycling streams. The quality of the materials streams can be reduced in each of the following recycling steps. These qualitative losses cannot be described by material balance. This paper presents the concept of exergy as a measure of quality losses, and gives the methods for the calculation of the exergy content and the exergy loss. Losses attributed to the recycling or material losses, material contamination losses and dilution requirements can be used as indicators for the materials quality loss as well as for the resource efficiency in the production systems. In this paper, the example of calculations on the steel scrap is presented.