In this study, the total materials requirement (TMR) to recycle chemical elements from the urban ore by recycling (urban ore TMR, UO-TMR) has been compared with the TMR to extract the element from the natural ore by smelting (natural ore TMR, NO-TMR) in order to evaluate the urban ore grade on an equal footing with the natural ore. A framework of UO-TMR based on the NO-TMR framework is developed. To validate the developed framework, the UO-TMR of a laptop PC is estimated assuming gold, silver, copper, iron, aluminum, tantalum and indium are recycled. It is found that the UO-TMRs for gold, silver, copper, iron, aluminum and tantalum are lower than NO-TMR, but that for indium is higher. The ratio of ''urban tailings'' is at most 60% of the total, which is smaller than that of NO-TMR ''tailings''. In contrast to the contributions of energy and material inputs for the recycling process, the contribution of transportation is not very large. For the UO-TMR of indium, the contribution of materials for recycling process is extremely large. The availability and scalability of UO-TMR are also discussed.

Total materials requirement (TMR) for the recycling of elements and materials (Urban Ore TMR) from end-of-life electric home appliances (cathode ray tube TV, liquid crystal display TV, refrigerator, washing machine, air conditioner and microwave oven) have been estimated and evaluated. The estimation were carried out using scenario analyses, in which the number of recycled elements and/or materials was changed considering additional energy for advanced recycling. As the results of the estimation, the urban ore TMR of gold, silver, copper and stainless steel were lower than TMR when they are smelted from natural ore (natural ore TMR) for all the scenarios. The urban ore TMR for iron (steel), aluminum and die-casting aluminum were mainly affected by the dilution ratio using pure element for the recycling. The recyclability of the elements and materials are discussed from the view point of TMR.

SummaryIn this study we introduce the concept of total material requirement (TMR) to quantify the quality of materials from end-of-life buildings. The TMRs for the recycling of materials (urban ore TMR [UO-TMR]) from four types of Japanese buildings ( Japanese traditional wooden structure [ JTWS], wooden frame with walls structure [ WFS ], reinforced-concrete structure [RCS], and steel-based structure [SS]) have been estimated and the trade-off between the increase in function of recycled materials such as steel made from scrap and the additional inputs of energy and materials required to create the increase in function were evaluated. Steel made from scrap, aluminum made from scrap, and road material are assumed to be recycled from steel products, aluminum products, and aggregate and cement concrete in the buildings, respectively. Case study analyses were carried out to determine the effect of recycling only aboveground materials compared to recycling both aboveground and subsurface materials. Also, the effect of varying the recycling rate of wooden demolition debris is determined.The UO-TMRs of steel made from scrap range from 4.7 kilograms per kilogram (kg/kg) to 18.2 kg/kg. Urban tailings (unrecycled components) account for the greatest proportion of the UO-TMR of steel made from scrap, and the next largest contributor is the recycling process. In the case of aluminum made from scrap, the UO-TMRs range from 22 to 196 kg/kg, with the contribution of urban tailings generally dominant, and the second largest contributor being on-site demolition and shredding. The UO-TMRs of recycled road material range from 1.04 to 1.16 kg/kg and are similar for different recycling cases and types of buildings.

In this study, the total materials requirement (TMR) to recycle chemical elements from the urban ore by recycling (urban ore TMR, UO TMR) has been compared with the TMR to extract the element from the natural ore by smelting (natural ore TMR, NO TMR) in order to evaluate the urban ore grade on an equal footing with the natural ore. A framework of UO TMR based on the NO TMR framework is developed. To validate the developed framework, the UO TMR of a laptop PC is estimated assuming gold, silver, copper, iron, aluminum, tantalum and indium are recycled. It is found that the UO TMRs for gold, silver, copper, iron, aluminum and tantalum are lower than NO TMR, but that for indium is higher. The ratio of``urban tailings'' is at most 60 of the total, which is smaller than that of NO TMR``tailings''. In contrast to the contributions of energy and material inputs for the recycling process, the contribution of transportation is not very large. For the UO TMR of indium, the contribution of materials for recycling process is extremely large. The availability and scalability of UO TMR are also discussed.

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