Evaluation of the Grade of Elements and Materials in Urban Mine by means of Total Materials Requirement

Abstract

Objective. The objective of present paper is to introduce an evaluation method of the grade of elements/materials in “urban ore” using Total Materials Requirement, TMR and to show issues of recycling, especially for home appliances, in terms of TMR.
Results and Discussion. The evaluation was carried out using the index of “urban ore TMR, UO-TMR” compared with “natural ore TMR, NO-TMR”. Assuming that only one element/material（gold, silver, copper, scrap steel, scrap aluminum or mixed plastics）is recycled from home appliances（cathode- ray tube TV, liquid crystal display TV, refrigerator, washing machine, air conditioner and micro wave oven）,only the UO-TMR of copper is less than NO- TMR, indicating that only copper is worth of recycling in terms of TMR. For all the target elements/materials, the impact of “urban tailings” is dominant. With increasing the number of recycled element/material, the UO-TMR of gold is drastically reduced because urban tailings is allocated for all the recycled elements/materials. The contributions due to transportation process are not large for all the cases investigated, compared with other processes. The effect of allocation method, the expansion of system boundary for the processing of urban tailings and the evaluation method of inferior recycled material are discussed.