Putra Hanif AgsonGani, Bandung Institute of Technology; Nuhindro Priagung Widodo, Bandung Institute of Technology
Ciguha underground gold mine at PT ANTAM UBPE Pongkor Indonesia, use cut and fill method to extract its gold. So, blastings a necessary and regular activity in its development and production phase. Poisonous and dangerous gases that trapped in mine need mine ventilations to clear them out. This occurrence leads to safety, at the other hand, also a productivity problems. Due to this matter, a comprehensive study is needed to know the effective re-entry time. The study consists of mine ventilation, dispersion of CO gas concentration and diffusion coefficient. Diffusion coefficient found by comparing the analytic (Taylor, 1954) and the survey result. At the end, the re-entry time formula will be determined. The re-entry time formula become a standard of how long the smoke clears at the certain location. The dispersion of CO gas is a site specific, and has been applied at the location which the study takes place. The diffusion coefficient value for each place are: X-Cut 477 is 0.37 m2/s, X-Cut 475 is 6.57 m2/s, and Footwall RD CGS is 4.91 m2/s. The result of the re-entry time is found by comparing L/D with the time dispersion of CO gas. This study could be further developed by applying Principal Component Analysis (PCA) to find a universal re-entry formula. And the function would be: Re-Entry = f{Velocity, Quantity, Tunnel Length, Diffusion, Friction, Powder Factor, Velocity of Detonation, Temperature, Relative Humidity}.
