Abstract: Economic evaluation on expansion project of a low-grade sulfide mine was made.According to the evaluation system of “with new project” and “without new project”,two opposite evaluation findings were obtained by computing two indicators of the incremental internal rate of return and the net present value of the incremental project respectively.The findings showed that as non-renewable and easily-exhausted resources,the mine has a constant reserve.At different calculation period of “with new project” and “without new project”,multiple internal rates of return were emerged,so the indicators have no reference value.Through statistical analysis on benefits and costs of the project,some projects including the original mine stripping,buildings and general plan and others that are treated as salvage according to a certain proportion,along with new investments,are considered as the total investment.Economic evaluation on the new project showed that this is a good approach and it can meet the requirements of the evaluation system.

Key words: Low grade of sulfur ore, Expansion project, Given period, Internal rate of return, Analysis