Abstract: In view that the optimization of the cut-off grade in ore drawing involves the whole mine system, a dynamic system study method is adopted. First, a mathematical model for all the dynamic link parameters of Daye Iron Mine is established, followed by establishing a comprehensive tech-economic model closely combining the technical parameters with economical ones. Secondly, What If function was used to make comparative analysis of thousands and hundreds of schemes and the policy-decision target values of all schemes are calculated. Finally, optimization decision-making is made by using twice multi-objective fuzzy comprehensive evaluation method. The optimized scheme can improve the three-year  total profit, present value and concentrate output by 25.9682 M yuan, 23.9436 M yuan and 0.1568 M t respectively.

Key words: Cut-off grade, Mathematical model, Dynamic optimization, Multi-objective fuzzy comprehensive evaluation method