Net smelter return - QueensMineDesignWiki
As a result, the copper and gold net smelter returns for copper concentrate sold to Smelter A are equal to $511 and $515 per tonne of concentrate, or $48.01 and $48.37 per tonne of ore. When these numbers are divided by the mill feed grade, the copper and gold NSR factors are equal to $20.69 per % Cu and $18.97 per gram of gold.