Known as the only metal with a PhD in economics for its forecasting prowess, perhaps Dr Copper was warning us of speculative froth as much as expected growth when it surged this year. 铜价的预测能力,使铜被称为唯一拥有经济学博士学位的金属。在今年铜价飙升之际,或许铜博士在反映预期增长的同时,也在向我们发出有关投机性泡沫的警告。
The useful elements of iron, copper, gold were retrieved from tailings by gravity concentration, magnetic separation, froth flotation and chemistry of metal, bricks, concrete, ceramics and other building materials were made from tailings at home. 国内主要利用重选、磁选、浮选、化学选矿联合工艺流程回收铁、铜、金等尾矿中的有用元素,利用废石、尾矿作建筑石料或加工制造砖、混凝土、陶瓷等建筑材料。