Rapid urbanization in 21st-century China has been fraught with contested demolition, overdevelopment and shoddy infrastructure with short lifespans. By viewing this infrastructure as having “high metabolism” and examining the urban scrap trade that is fuelled by its material outputs, this article challenges a common assumption that such a form of urbanization is merely wasteful and problematic. Crucially, such urbanization also puts rural migrants and scrap into motion in a way that helps to reproduce its form. This occurs by generating socio-material nodes of scrap trading wherein migrants make the most of temporarily stable situations with entrepreneurialism. The nodes are spaces of “suspension” shaped by challenges including cheap rental housing that is often targeted for demolition and frequent harassment from the authorities. However, the challenges do not prevent scrap traders from caring for kin, attending to human sentiments and sometimes achieving social mobility.

Aluminium (Al) consumption growth exceeded those of all other major metals over the lastdecades. The main driver for this development is the broad range of applications for Aland Al-alloys. As the growth in consumption went along with an increase of anthropogenicstocks and flows of Al, information about material cycles became a crucial issue in termsof resource management. In this study a comprehensive material flow analysis (MFA) of theflows and stocks of Al in Austria for the year 2010 is conducted. The focus of thepresented Al balance is on data harmonization and plausibility checks, both based onextensive data and literature research. The stock of Al is derived from bottom-upcalculations indicating a total stock of about 260 kg Al per capita with an annual growthof 11 ± 3.1 kg/cap yr in 2010.Total old Al scrap generation is calculated to be 7 ± 1 kg/cap yr. For considering dataquality aspects of single input data an adopted method for uncertainty assessment has beenapplied to the different material flows. This allowed a consistent evaluation ofuncertainties within the material flow model. Due to the substantial uncertaintiesassociated with end-of-life Al flows and their significance for secondary Al production inAustria, a better data base is needed in order to evaluate and optimize national Al scraputilization in secondary production. Therefore, a dynamic MFA model will be built forAustrian Al flows and, in conjunction with the results from the static analyses, willprovide a reliable decision basis for future Al resource management.

When introducing a new control paradigm in industry or society one has to accept that it is an evolutionary process where people, methods and processes must develop simultaneously, and this takes time. The recycling of material has been studied intensely for the last ten years using different approaches to material flow analyses, MFAs. They have given a good view of the magnitude of material flows but their use has been limited by lack of relevant data. In the case of recycling, data must be acquired from the practitioners of the trade and in order to get it, the value of the output for them and for society must be proved and visualized. This paper is based on a MFA model developed at KTH for steel flows in Sweden (part of the Swedish environmental research program, the “Steel-Eco-Cycle”). The aim of the work reported on here was to initiate the process of motivating better sampling of data in industry and society for performing MFAs. The KTH model is based on a product-to-product approach for steel, describing the recycling machine. Data is presented in a simplified model for Sweden with total figures and figures per capita. Areas where improvements can be made are identified and ways to “lubricate” the recycling machine are discussed. The main idea is to provide a way of describing flows that can be of use to recyclers and steel producers and form a basis for discussions on improvements. Finally, the underlying model is briefly described and the uncertainties of data are discussed.