某矿为多金属矿山，矿石成分复杂，可回收的元素有Au、Cu和Mo。由于含有多金属成分，并且金铜精矿混合在一起进行冶炼，因而金属回收率的计算十分复杂。运用微积分原理对选矿生产中的理论回收率及产率进行推导，进而计算出各元素理论品位值，使回收率更趋于精确化，可以平衡取样和化验等方面产生的误差。

For a multi-metal mine，its ore components is complex，and the recyclable elements have gold，copper and molybdenum.As it contains multi-metal components，and the gold concentrates and copper concentrates are mixed and smelted together，the calculation of metal recovery is very complicated.Using the calculus principles deduce the theoretical recovery and the productivity which in the process of mineral production.Then the theoretical values grade of each element is calculated，and that making recoveries tend to be more precise.It can balance the error which concludes the aspects of sampling，testing，and so on.