STUDY ON OPEN PIT OPTIMISATION BY WET MINING AND DRY MINING METHOD FOR QUARTZ SAND MINING FROM PROCESSING RESIDUES IN PT TIMAH TBK.

• Main Author: Zidan Amali, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69402
• Institution: Institut Teknologi Bandung

Quartz sand is one of the precious non-metal mining commodities, especially in the glass and construction material industries. As a tin mining company, PT Timah Tbk. produces a large amount of quartz sand from processing residues which has some good quality in grade and potential to be mined and processed. Therefore, it is necessary to carry out a pit optimization process on that quartz sand block model to determine the amount of mineable quartz sand reserves and the maximum undiscounted profit value (net value). The mining software, namely Micromine 2021, will execute the pit optimization based on two mining method options, wet mining and dry mining. Wet mining or hydraulic mining uses high-pressure water to dislodge the material. Dry mining uses excavators and dump trucks to dislodge, load, and transport the mineable material. The difference between the two mining methods is that there are several input parameters in the pit optimization process, such as mining recovery, mining dilution, processing recovery, mining cost, and processing cost. Then, the results obtained from the pit optimization process are in the form of a pit shell. A pit shell can show the amount of quartz sand reserves, reveal the net value, and become a reference in designing the ultimate pit limit (UPL). So, there are two UPLs for each method. The results of the UPL design will reveal the difference in the quantity of mineable quartz sand reserves between the two methods. In addition, there is sensitivity analysis based on the fluctuations in the selling price of quartz sand and the operating cost of the amount of quartz sand reserves produced from the pit shell for both mining methods. The final result of this research is that the wet mining method gets more quartz sand reserves than the dry mining method, which is 528,031 tons compared to 526,111 tons for the results from the pit shell and 590,226 tons compared to 511,200 tons for the results from the UPL design. In addition, the fluctuation of the selling price of quartz sand has an effect in the form of a directly proportional relationship to the amount of quartz sand reserves. Meanwhile, the fluctuations in operating cost have an inverse relationship to the amount of quartz sand reserves.