一、绪言近年来,随着钢铁工业迅速地发展,需要的铁矿石正在显著地增加。然而在70年代以来,就铁矿石资源而言,世界性出规富矿石枯竭的趋势,则确保高品位铁矿石逐渐地成为困难。例如,美国铁矿石的采掘品位1951年为49.5％,而1971年降为34.0％;苏联1965年为40.8％,而1970年降低为37.3％,1976年降低为36.1％。为了扭转这种 I. INTRODUCTION In recent years, with the rapid development of the steel industry, the amount of iron ore needed is significantly increasing. However, since the 1970s, the trend of depletion of world-regulated ore in terms of iron ore resources has ensured that high-grade iron ore gradually becomes difficult. For example, the U.S. iron ore mining grade was 49.5% in 1951, down from 34.0% in 1971; the Soviet Union was 40.8% in 1965, down from 37.3% in 1970 and 36.1% in 1976. In order to reverse this