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Critical Path Identification Sample of CPM and PERT Approach can show the estimation of time spent to finish the project with assumption of Optimistic, most likely, pessimistic and variance activities.
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. Development is a process of making aperture (tunnel) is done by dismantling (excavation) both manually and mechanically. The results to be obtained that is in the form of opening holes according to Grasberg Block Cave (GBC Mine) production plan based on the purpose of the open pit function. Propose is done to support other fix facility in order t...
Citations
... GBC is one of future mines with the block caving mining method in PT Freeport Indonesia. The development cycle carried out in the GBC mine production area includes surveying, drilling and blasting, loading and hauling, scalling, and supporting installation [1]. Some underground mining areas in PTFI are Kucing Liar, Big Gossan, Deep Ore Zone (DOZ), Deep Mill Level Zone (DMLZ), and GBC [2]. ...
PT Freeport Indonesia (PTFI) applies two mining systems, open pit mining in Grasberg and underground mining. This study was carried out in the Grasberg Block Cave (GBC) underground in extraction level at panel area, one of the underground mines located just below the Grasberg open pit mine by the block cave method. At present, GBC is in the development process, one of the cycles in development process is supporting installation. Supporting installation is the last cycle which include two operations, namely primary support installation and secondary support installation. The study was conducted on primary support. Primary support is the operation after excavation has been completed and aims to strengthen the rock mass (reinforcement). The use of primary support material actually experiences a significant increase so a technical study is needed to determine the difference between material requirements based on the design and actual conditions. After that, an evaluation is carried out by redesigned the support system based on rock mass classification of the Q-System to obtain a safe support recommendation. The Q value for Panel 16 is 0.7 including to the poor rock mass. The Q value for Panel 14 is 2.9 including to the fair rock mass. According to this study, recommendations are obtained using a split set length of 2.1 meters and 1.3 meters spacing and resin bolt with a length 2.4 meters and 1.2 meters spacing for panel areas with poor and fair conditions. Numerical modelling with finite element method is done with the help of Phase2 software version 8.0 determine the strength factor of the recommendations obtained analytically. Based on the results of the modelling, it is found that the smallest strength factor is 1.3.
Deterioration of mining conditions at mining deposits by open pit methods (increased mining depths, reduced ore deposit thickness) leads to an increase in mining costs. In Ukraine, to reduce open pit mining costs, overburden is disposed in temporary internal dumps located directly in the open pit over the ore reserves. Reactivation of pit areas with the temporary internal overburden dump located on them results in a surge of mining operations and deterioration of technical and economic indicators. Increased energy consumption, a decrease in working site parameters, an increase in angles of open pit slopes and stripping lags lead to unprofitability of open pit mining. One of the solutions to the mentioned scientific and engineering problem involves combined mining of deposits by integrated open pit and underground mining operations. The combined open pit-underground mining method enables reducing mining costs and enhancing technical and economic indicators. The suggested schemes for opening reserves located under the internal overburden dump enhance technical and economic indicators of deposit mining through making the internal dump a permanent one. This allows further disposal of overburden into internal dumps. Implementation of scientific recommendations and technological solutions resulted from the research performed (exemplified by the deposit Hannivske, Ukraine) reduces the cost of ore by 1.33 USD/t. At the same time, the total cost of building an underground mine makes 16.4 M USD, which is 30% less than when applying traditional opening vertical shaft schemes.
Deterioration of mining conditions at mining deposits by open pit methods (increased mining depths, reduced ore deposit thickness) leads to an increase in mining costs. In Ukraine, to reduce open pit mining costs, overburden is disposed in temporary internal dumps located directly in the open pit over the ore reserves. Reactivation of pit areas with the temporary internal overburden dump located on them results in a surge of mining operations and deterioration of technical and economic indicators. Increased energy consumption, a decrease in working site parameters, an increase in angles of open pit slopes and stripping lags lead to unprofitability of open pit mining. One of the solutions to the mentioned scientific and engineering problem involves combined mining of deposits by integrated open pit and underground mining operations. The combined open pit-underground mining method enables reducing mining costs and enhancing technical and economic indicators. The suggested schemes for opening reserves located under the internal overburden dump enhance technical and economic indicators of deposit mining through making the internal dump a permanent one. This allows further disposal of overburden into internal dumps. Implementation of scientific recommendations and technological solutions resulted from the research performed (exemplified by the deposit Hannivske , Ukraine) reduces the cost of ore by 1.33 USD/t. At the same time, the total cost of building an underground mine makes 16.4 M USD, which is 30% less than when applying traditional opening vertical shaft schemes.
