Abstract: At present,Magang Gaocun Iron Mine is facing the status quo of the second phase project is about to reduce production.In order to extend the stable production life of the mine,it is planned to carry out the construction of the third phase project in the west of the stope.The thesis introduces the plan of the third phase mining in the stope.Combining the current status of the mine and the characteristics of mineral resources,the mining difficulties during the transition period from the second phase to the third phase are explained.The advantages and disadvantages of steep slope mining and gentle slope mining are compared and analyzed.It is pointed out that steep slope mining can balance the production stripping ratio and reduce peak stripping,which is a suitable expansion method for stable production in the transition period of Gaocun mine.At the same time,combined with the characteristics of the mine,it is recommended to use the goosetracking steep side mining scheme.The net present value of production cost is calculated according to the dynamic method.Under the condition of ensuring stable production in the transition period (20212027),the steep slope mining can save direct costs of 34.215 million yuan compared with the gentle slope mining,and the economic benefits are very significant.

Key words: phased mining,production transition period,steep cut mining,economic benefit