关于金属物质社会蓄积量的分析

Analysis of Social Stocks of Metallic Substance

金属的社会蓄积量在一定程度上决定了可供回收的二次资源的数量．给出了金属物质社会蓄积量的两种分析方法．从理论上分析了金属消费量呈线性变化和二次曲线变化情况下金属物质社会蓄积量的变化．以我国铜工业为例，根据1950-2007年我国铜消费量的变化情况，分析了此期间内铜的社会蓄积量的变化，2000年以后铜社会蓄积量进入了快速增长期；给出了金属社会蓄积量的平均年龄的概念及其计算公式，并分析了此期间内铜社会蓄积量中制品的平均年龄，1988年以后铜社会蓄积量中制品的平均年龄基本上逐步下降，2005-2007年间基本稳定在7．8年左右．

Social stocks of metallic substance determine the secondary or recoverable resources to a certain extent. Two methods are given for the social stocks to analyze theoretically the variation of social stocks of metallic substance with the assumption that the metal consumption presents linear or quadratic curves. Exemplifying the copper industry in China, the variations of social stocks of copper and its consumption in the period from 1950 to 2007 were analyzed and the results reveal that the social stocks have come into a quicker growth period since year 2000. Proposes the notion of average age of social stocks of metals and its calculating formula, and an analysis is made to the average age （aa） of copper products in social stocks in the period. It is found that aa of copper products in the period decreased gradually since 1988 and basically remained unchanged from 2005 to 2007, i.e. about 7.8 years.