持続可能な社会における資源供給―多様な資源をとりまく複雑な動き

Abstract

Currently more than 40 metals are systematically extracted and used in many different fields in civilized society. The quantities and qualities of the metals had been increasing after the Industrial Revolution. Especially, the pace continues to accelerate remarkably with advances in technology and globalization during the past several decades. The current frameworks of supply-demand for the metal commodities were assessed from the standpoint of the statistics, geology, and economics. Wide ranging scope of quantity, market, price, and uneven distribution of geological factors are illustrated using a logarithmic scale. There is no general model or economic analysis applicable to all metal commodities. Recycling and/or reuse have become very important because recycling contributes to supplying the material needs of society and protecting the environment. A number of factors that vary from metal to metal influence the recycling of old scrap. Values in old scrap recycling seem to be assessed based on various combination of four major factors, (a) primary production costs, (b) environmental benefits, (c) a fear of poisoning and (d) a fear of mineral depletion. As a result, it is not realistic that all waste materials are capable of being recycled, because recycling metals have fundamentally been competing with primary production.Metal prices are determined by a number of factors, such as costs, technology, strikes, and policies that affect individually each metal price. It is observed that an immediate-run price rose often to few times that of long-run price due to extraordinary variables. For example, distinct properties of the six platinum group metals such as catalysts, stable electrical properties, resistance to chemical attack, and excellent high temperature characteristics have been exploited for industrial applications by advanced technologies during three decades. Since 1979, autocatalysts has emerged as the principal consumer of Pt-group metals. Platinum-palladium mix was used first to oxide the unburned hydrocarbons and carbon monoxide, and then it was replaced by a palladium-rhodium mix that oxide the unburned hydrocarbons and carbon monoxide and reduced nitrogen oxides according to the national legislation. Prices of Pt-group metals have alternatively risen and fallen, because they are determined in competitive markets based on balance of supply and demand. Fluctuations in Pt-group metals prices after 1970s mark a phenomenon not previously seen before using Pt-group metals in a number of their applications using advanced technologies