中国における銅鉱床に関する品位 : 鉱量モデル Grade-Tonnage Models of Copper Deposits in China

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Author(s)

    • 張 欽礼 ZHANG Qinli
    • 東京大学大学院工学系研究科 地球システム工学専攻 Department of Geosystem Engineering, School of Engineering, The University of Tokyo
    • 正路 徹也 SHOJI Tetsuya
    • 東京大学大学院新領域創成科学研究科 環境学専攻 Department of Environment System, School of Frontier Sciences, The University of Tokyo
    • 金田 博彰 KANEDA Hiroaki
    • 東京大学大学院工学系研究科 地球システム工学専攻 Department of Geosystem Engineering, School of Engineering. The University of Tokyo

Abstract

中国の銅鉱床の品位,金属量,鉱量を統計的に解析した。品位と金属量,および品位と鉱量はほとんど相関がないのに対して,鉱量と金属量とは強い相関がある。品位,金属量および鉱量はそれぞれ対数正規分布をする。鉱石中の銅価格の割合(<i>R</i><sub>Cu</sub>) によって,銅鉱床を二つのグループ,すなわち銅を主産物とする鉱床(MC:<i>R</i><sub>Cu</sub> ≥ 0.5) と副産物とする鉱床(AC:<i>R</i><sub>Cu</sub> < 0.5) に分けたとき, MC 鉱床の品位- 鉱量モデルは高品位部(> 3.0%) と低品位部(< 2.0%) を表す二つの指数関数の組合せで近似できる。低品位部を表す指数関数から得られる臨界品位は0.34% である。現在いくつかの鉱山が採掘品位をこれより下げても金属量がたいして増加しない臨界品位付近で操業しているので,中国の銅資源は悲観的状態に移りつつあるといえる。随伴金属を銅品位に加味した銅相当品位と鉱量の関係における臨界銅相当品位は0.43% である。臨界銅相当品位で見ても,中国の銅資源は悲観的状態に入っている。

Copper-bearing deposits of China are statistically analyzed in terms of ore grade, metal amount and ore tonnage. Ore grade correlates to neither metal amount nor tonnage, while metal amount depends largely on tonnage. Each of grade, metal amount and tonnage shows more or less a lognormal distribution. Based on the ratio of copper in ore value (<i>R</i><sub>Cu</sub>), Chinese copper deposits are classified into two groups: mainly copper-producing deposits (MC : <i>R</i><sub>Cu</sub> ≥ 0.5) and accessorily copper-producing deposits (AC : <i>R</i><sub>Cu</sub> < 0.5). The grade-tonnage relation of MC deposits can be combined by two exponential functions approximating high grade (> 3.0%) and low grade (< 2.0%) parts. The critical copper grade, which is obtained from the low grade part of the relation, is 0.34%. Since less metal amounts are expected with decreasing ore grade below the critical grade, Chinese copper resources are concluded to become pessimistic, because some mines are working with grades close to this critical value. Taking account of the fact that many copper deposits are actually polymetallic, Cu-equivalent grades, which are converted from ratios of metal prices to the copper price, are also introduced. The critical Cu-equivalent grade of MC deposits (0.43%) is also suggesting that Chinese copper resources are pessimistic.

Journal

  • Shigen-to-Sozai

    Shigen-to-Sozai 120(1), 19-24, 2004-01-25

    The Mining and Materials Processing Institute of Japan

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