The implications of improved conveyor technology on in-pit crusher conveyor systems

Abstract

Open pit mines are beginning to reach depths previously considered impossible, due to moderntechnology, geotechnical advances and fluctuating commodity prices. Open pit haulage costscurrently account for up to 60% of the total mining operational costs, and with increasing depth,the haulage distance and hence the number of trucks required to satisfy production hasincreased. This creates opportunities for alternative material transportation methods to replacethe conventional TS system. This research project aims to investigate the performance of asemi-mobile IPCC system as replacement to TS operations in an open pit copper-gold mine.An extensive review of literature regarding open pit mining systems and mine planningconcluded that there is a gap of understanding in the industry for determining the optimumsystem for open pit metalliferous mining. A review of literature highlighted a shared ideologythat whilst IPCC systems present the benefit of much lower operating costs, increased safety,and lower dust and GHG emissions, the system represents a significant up-front capitalinvestment which the mine is only able to depreciate over a sufficient mine life. IPCCimplementation requires extensive mine planning and scheduling, often requiring large wasteproduction early on in the mine life, deterring mine planners away from the advantages that thesystem is capable of providing.A copper-gold deposit block model underwent mine planning using two separate miningsystems, semi-mobile IPCC as well as TS. Two IPCC pits were designed, IPCC 26B and 36Bat depths of 390 m and 540 m deep respectively. A conventional TS pit was designed, with anoptimum depth of 525 m. IPCC yielded the greatest total undiscounted pit revenue, howeverapplying production scheduling and a discount rate to the revenues found that TS had thegreatest total discounted value. IPCC presented lower operational costs than TS, with savingsof up to $1.43 per tonne of material moved, and up to $36 M annually in OPEX.Applying the capital costs on a yearly basis found that TS had the lowest CAPEX requirement,due to truck implementation over time compared to the large upfront CAPEX that wasnecessary for IPCC operations. Using the yearly cash flows, OPEX and CAPEX, an FTM wasgenerated. The TS pit yielded the greatest NPV, with $1.325 B, including an IRR of 63%.Making the TS mining method the most economically viable mining method for the givendeposit, and the most ideal mining system in countries where NPV is regarded as the highestpriority in mine valuation. Whereas, the large recovery presented by IPCC 36B indicates that IPCC systems can be selected as the most ideal mining system in countries that value recoveryover NPV in mine valuation, such as Post-Soviet countries.Further work consisted of investigating similar comparisons between IPCC and TS systemswith varying deposits, pit exit strategies and crusher portability modes. It was alsorecommended that an existing IPCC mine be compared with a theoretical TS mine simulation,using real life cash flows, OPEX and CAPEX to reduce the chance of error in the investigation.