Dear Henk,

I offer the following non-exhaustive notes on Monte Carlo Simulation input data.

I do not believe that such a generic database exists. We have modeled many such systems and always must build the model for the site specific conditions as noted below.

You might try Prof. John Sturgle at the Univ. of Idaho. He may wish to aid you. website: www.sturgul@uidaho.edu See his pubication: www.modelingandsimulation.org/MayMining.html

Dr. Alex Lebedev may be willing to help with a reasonable database there in South Africa. He helped us on the original ESKOM 143 km overland study using one of the Monte Carlo tools. The original study was only indicative and not exhaustive. He can be reached through Phil Staples (CKIT).

Mechanical Rotating Equipment :

a) Mean-time-to-failure (MTTF)is calculated from the bearing ratings, loading time based histograms, and Palmer's (not Miner's) damage failure related criteria (non belt related )

b) Mean-time to- repair (MTTR) is provided by site history such as: spares inventory, mobility, crew and lifting equipment availability, instrumentation and diagnostic aids, etc. -- can vary with the client including: location, country, shift, preventive maintenance schedule influences and programming ( normally a part of item (a)), weather, etc. These and other events all add or reduce the time to identify the problem, the problem cause(s), call for the appropriate resources, execute, debug; commission. Taking data out of context is not appropriate for meaningful simulation.

NOTE: Building of the model also must include large periods of downtime, although infrequent, for consequential damages and their risk implications, such as fire, flood, lightening, storm damage, and other damage events. Proper preventative maintenance can anticipate likelihood of failure, in a elected time period, and alter the MTTF and MTTR for the model.

Non-Rotating Equipment (eg. belting):

a) Belts rips -- depend on: the type of mine, the detection and protection against tramp material damage, rock containment on slopes, at head transfer/transition chutes, at load station and skirts -- against being fed into to the pulley nip, the build up potential on pulleys (drive; non-drive), the type of liners in chutes, etc.. Engineers overlook the importance of belt damage potential and most often do not design to the potential risk. Therefore, the number ususally needs to be developed by, or reviewed by, a third party that is removed from the design team.

The above notes are not exhaustive but just a introduction on the matter.

Electrical & Instrumentation:

IEEE publishes exhaustive data on MTTF & MTTR for all manner of electrical substation equipment, CB, MCC, motors, and many types of instruments. Furthermore, most prominent manufacturers can provide these paramters for their specific products and guide you in the added necessities or penalties to optimize the call for the design. I do not have the latest. I am sure this can be tracked down.

My regards to Mr. Danny Odendahl.

Lawrence Nordell

President

Conveyor Dynamics, Inc.

www.conveyor-dynamics.com ■