桑园铁矿露天转地下开采方法的选择

露天转地采矿山一般选用基建周期短和采矿成本低的地下采矿方法,如崩落法。然而,随着环保和土地保护的要求,矿山的开采一般不允许产生新的地表塌陷,转而采用充填法,对露天转地下矿山过渡时期的经营不利产生不利影响。由于露天开采已经对露天境界内地表造成了破坏,允许二次破坏,桑园铁矿提出了上部采用崩落法,下部采用充填法技术方案。为此,采用工程类比法和Laubscher法初步选定崩落法开采的高度,采用离散元的数值计算方法,开展了崩落采矿高度和碎石覆盖层厚度联合选择研究,最终确定崩落法采矿的深度为108 m、碎石覆盖层的厚度为40 m。经济分析表明,桑园铁矿采用上部崩落法下部充填法联合开采,不仅可推迟充填站建设时间,而且节省约1亿元采矿成本。

Selection of Mining Method of Transforming from Open-pit to Underground for Sangyuan Iron Mine

Some mining methods such as caving method, which have short construction period and low mining cost, are often selected for mines changing from open-pit to underground. However, as ecological and environmental protection getting more and more attention, surface collapse induced by underground mining is not permitted so that upward backfilling method with relative longer construction period and larger investment tend to be adopted by mine, which is harmful to mine management in transition period. Open-pit mining has already caused damage to the surface, so collapse is permitted inside the open-pit limit, therefore Sangyuan mine decide to combine caving and backfilling method for its transition to underground mining. Firstly, the engineering characteristic of Sangyuan Mine is introduced. Then, engineering analogy method and Laubscher method are used for preliminary choosing the depth of cave mining. Finally, based on the coupling analysis of block distinct element method (DEM) and particle DEM, the depth of cave mining and the thickness of covering layer are determined. Economic analysis showed that, with the combined mining method Sangyuan mine can not only overcome difficulties in transition period, but also save mining cost up to nearly 100 million Yuan.