Abstract
The effective utilization of materials found in what have come to be termed urban mines, (stockpiles of waste materials found in consumer-based cities), has become a crucial waste issue in Japan. It is therefore now necessary to evaluate not only the quantity in waste piles, but also the quality (grade) of materials found there. This paper introduces the concept and position of TMR (Total Material Requirement) as a prospective streamlined substitute indicator as compared to other indicators. An expanded concept of TMR, an urban ore TMR (UO-TMR) developed by the authors, is also presented. Using the UO-TMR, the grade of materials located in an urban mine can be evaluated as an expanded elemental concentration that takes into consideration additional material and process inputs as a negative factor. Some examples of this evaluation method are shown using cases of PC laptop recycling. The effects of tailings and urban tailings, which have rarely been points of focus previously, are also discussed here.
