Abstract: Based on the theory of floating cone exclusive method， the ultimate boundary of two open pits in different producing conditions was optimized together by Smart Miner software. In view of the technical and economic parameters being different in open pits and the optimization results being sensitive to these parameters， the software incorporated some functions to indentify the partitions of mining objects and optimized the boundary by the corresponding parameters in each partition. Meanwhile， the software incorporated the function of optimizing boundary in any constraint ranges for the mining range being restricted by the surface structures. Taking Sijiaying open pit as an example， the ultimate boundary was optimized with restrictions and non-restrictions according to the parameters in different partitions. The results showed that the surface structures which caused 0.1 billion ore loss were a strong constraint to the optimum boundary. The 0.1 billion ores formed hanging wall ores from -202m level. If the hanging wall ores were still mined opening， the cost of moving surface structures must be less than 0.34 billion.

Key words: boundary optimization, floating cone method, open pit mine, profit value, model