Damage Prediction in the Extraction Level of Block Caving Mine - Case study in Deep Ore Zone Mine, PT Freeport Indonesia

摘要

Damage on the extraction level of a Block or Panel Cave mine can have tremendous impact not only on the availability of an open productive area but also in the cost of repairing and the opportunity cost of not producing from a given area prepared and developed to be in production. The study of the underlying mechanics of damage could facilitate the intrinsic modeling of computation for active layout availability and therefore produce more reliable production estimates. Several mines around the world looking at block or panel cave mining as a mining system should be aware that depending on the strength of the rock mass, the induced stress as a result of mining activities and the dynamic loading as a function of seismicity could facilitate the occurrence of damage across an active production layout as means of structural damage of drifts and brows, rock collapse and rock burst. This paper summarizes the experience of DOZ mine of PT Freeport Indonesia in relation with damage of production areas where the main concern is to be able to forecast potential losses of infrastructure due to damage from migrating between skarn into a diorite rock mass. The work performed at DOZ consists of analyzing in terms of statistical significance several indicators related to rock mass behaviour, induced seismicity, mine design and mine planning in a 50 cases database collected over the period 2005 to 2008. It is found that the rock mass behaviour, seismicity, mine design and production planning contribute in 31%, 27 %, 23% and 19% to explain the damage occurrence at DOZ. Based on this statistical analysis a regression analysis is computed as means of a methodology that could be mimic at other mining operations. There is no intent that this regression analysis is used as a mine design nomogram at other mine sites but rather to be used as a methodology to integrate different areas into the design and planning of a mining system.