For a mine to be changed from an open pit to underground stope, the stability of the boundary pillar has direct influences on the safety production of the mine.

此时为了处理好露天与地下同时开采相互影响的问题，一般采用空场法，它需要在露天坑底部、地下开采第一中段的矿房顶部保留一定厚度境界顶柱。

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In this paper, the research is carried out deeply aimed at the problems of the structure parameters of underground stope for transition from open pit to underground Mining in Shirengou Iron Mine.

针对石人沟铁矿露天转地下过渡期开采I区地下采场结构参数问题展开了深入研究。

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The hanging wall ore of the open-pit is one of important projects in transition from open pit to underground in Daye iron mine, and the shallow hole shrinkage mining method is adopted in the project.

大冶铁矿露天采场挂帮矿是该矿山露天转地下项目的重要工程，采用浅孔留矿法进行开采。

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Encina said Codelco is working to convert one of its biggest mines, Chuquicamata, from open pit to underground.

FORBES: Continuous Mining To Help Chile Extend Mine Life, Save Money

Open pit mines cannot be converted to underground mines.

FORBES: Continuous Mining To Help Chile Extend Mine Life, Save Money