Author/EditorTESELETSO, LARONA SETHUNYA
Alternative Title鉱物資源の長期供給可能性とTMRを元にした環境インパクトの定量的モデル化
Note (General)Historically, mineral resources have been vital in engineering the modern society. However, over the last few decades, the surge in demand of these resources for their specific usage changing the market landscape, has raised concern of their future availability. As the demand for metals rise, the metal prices simultaneously rise, further increasing the anxiety in physical scarcity and quality of these metals. In addition, the absolute decoupling of the environment from resource activity is a necessity to ensure that economic development progresses without harming the environment.To sustainably plan for our future resource requirements, creating a supply model for these metals is critical to understand how much resources will be economically accessible at a given grade, which is a measure of the metal quality. If there is a shortage, how much recycling production quantities are needed to meet the increasing demand of these exhaustible metals. Vulnerability to the environment caused by these anthropogenic activities is a confronting issue in the society that also requires attention through modelling their sustainable projections based on future metal production patterns.There remain few studies that examine long term trends in mining production and linking them to environmental sustainability based on factors such as ultimate recoverable resources, increasing production quantities, declining ore grade, and mine waste (overburden and mine muck) and ultimately how recycling promotion will ameliorate the shortage of primary metal supply to satisfy metal demand. Therefore, the study investigates the future resources and their grade qualities by geographic location, their supply and demand long term trends, and the degree of vulnerability on the environment created by these metals during metal mining activities. The analysis period of this study ranges between 1990-2070.The long term future availability of resources proposes a quasi-dynamic approach that measures economically extractable reserves to determine the physical scarcity of resources. The limit of future reserves is determined by ultimate recoverable reserves at a given cut off grade. The deteriorating metal ore grade creates a concern of future resource quality and ultimately how this inherent nature harms the environment. The environmental impact is tracked based on the total material requirement indicator. This indicator is dependent on changes of strip ratio and ore grade during metal mining production. A comparative analysis of six metals namely copper, gold, iron, lead, nickel and zinc whose importance to the basic applications of modern use in society has risen is evaluated to identify the resource lifetime, quantity and quality by geographic location is applied. The study identifies that physical scarcity is unlikely to occur in this century, but the physical peak of some resources will occur earlier than others as the mining industries become fully matured. Gold for example, has an early Hubbert’s peak contributed by the long historical mining history, resource size and occurrence. The total material requirement depicts that gold attributes to the largest environmental harm compared to copper, nickel, lead, zinc and iron ore with the least impact. This is because larger material volumes of gold are removed to access the low ore grades and thin veins of gold ore deposits. For copper, the Latin American region experiences high potential negative environmental impacts compared to other regions mainly because of the high global extractions in the top copper producer country, Chile, where similar high ore TMR trend patterns are experienced. Nickel, lead and zinc have similar trend patterns to copper due to their close association in occurrence. For iron, even though it has the least impact on the environment, positively spiking anomalies in the ore TMR trends in Australia synonymously with the Asian Pacific region due to historical large scale increase in production for iron from Australia for exports to consuming countries. The dynamically varying ore TMR trends therefore outlines the importance of investigating ore TMR trends with unique individuality to tackle these potential concerns on the environment.With regards to the promotion of recycling, system dynamics modelling using STELLA software is carried out on copper, gold and iron to investigate the future total supply trends to satisfy the metal demand by application. By investigating additional supply, factors such as the recycling rate, recycling efficiency, recyclability potential and the environmental implication on the total system boundary are applied. Primary production will remain the largest contributor of copper supply to 2070 while production ratio of primary and secondary supply is almost equivalent over the same period. Finally, we observe the resource outlook based on the United Nations Environmental Programme-International Resource Panel scenarios ideal to achieve the Total Sustainability and Recycling Efficiency scenarios. By achieving these scenarios, a 25% and 17% reduction, respectively, in global extraction are proposed. The study outlines these adjustments relative to increasing consumption as primary production declines whilst maintaining the same current demand levels. The appreciation of these to manage our future resource would ultimately reduce the outcome of future ore TMR patterns during metal mining production.From a sustainability perspective this study demonstrates that the trends of primary production will increase the environmental footprint in the future as the total economic and non-economic material flows increase and the associated metal ore grades decline. However, the promotion of secondary metal sources will provide an alternative supply source should availability of primary resources be constrained. Therefore, tracking of both economic and non-economic material flows is crucial for effectively decoupling resource activity from the environment.Mineral resources are a fundamental component to the global society and economic growth. Although the combination of forecast trends on mineral production based on the URR values and promotion of recycling as a secondary metal supply source outline that a supply risk is not eminent to 2070, this study did not include other factors of uncertainty such as economic, technological and social factors in which future systems modelling could be improved. However, the study provided and important basis towards the total material flow of resources to establish material efficiency in the quantities and quality of resource use. Further, accountability of resources through material flow tracking is discussed, providing a basis for quantitative assessment on environmental implications.
Collection (particular)国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文
Date Accepted (W3CDTF)2022-07-05T02:30:21+09:00
Data Provider (Database)国立国会図書館 : 国立国会図書館デジタルコレクション