The hours of operation can only be determined by the user as to how much material you want to move over a given time period. This will only give you a required TPH (tons per hour).

Typically a system is designed to be somewhat greater than the operational requirements. Future expansion may also want to be considered.

A conveyor system designer will need at a minimum the following information:

TPH - tons per hour

HD - horizontal distance head to tail.

TL - total lift head to tail

PD - product details - bulk density, lump/particle size, moisture content, temperature, etc.

transfer points if any or is it one single conveyor?

This is like I say only the bare minimum. From there you can then work with a consultant to have your system designed according to the standards that are applicable to your country.

Good luck,

Gary Blenkhorn ■

For coal operation with a proper operating and maintenance plan, 6000 hrs/y is OK. Some operators have extended the limit to 7000 hrs./y. Large capital systems work for more than 18 hours per day. The 18 hour figure in a nominal or average spread over many scenarios and production procedures.

First, you must have detailed understanding about the planned maintenance versus expected downtime and repair time given outage likelyhoods. This includes production time, shift change time, planned maintenance time, holidays, production starvation, and unplanned loss of production integrated into a most likelhood set of conditions caused by many events.

Thus, mean time between failures (MTBF) and mean time to repair (MTTR) yield the nominal availability index. A complex site of many machines and stockpile options should be evaluated using Monte Carlo simulation tools.

Couple Monte Carlo and an LP shadow cost and shadow profits procedures will provide the necessary trade-off decision mechanism. THe Monte Carlo model is normally run 1000 times or more to get a statistical spread on variablilities and the power of the statistics to evaluate risk and benefit of all definable options.

The Monte Carlo tool should be used for new projects including plant sconstruction scheduling and financial planning estimates and variances as well as debottle-necking or expanding existing facilities.

This method can act as the driver for most large financial actions. ■

Hello all

I covered this in one of my two papers that were presented at Beltcon 13 this year.

In the paper I explained how to calculate the overall availability of a string of materials handling components in series and operating hours per year.

Having established the overall availability, you then have to calculate the utilisation, which is based on hours per shift, shifts per day, and days per year. On top of this, you have to allow for bad weather days, public holidays, scheduled outages, downtime for shifting systems if applicable, and so on.

The inclusion of correctly sized and positioned stockpiles often makes a massive difference, as does the ability (or especially inability) of the system you are feeding, to actually be able to receive material when you want to run the materials handling system.

You then combine the availability with the utilisation to finally calculate the realistic operating hours per year.

I have just calculated the operating hours a materials handling system for mine waste in India.

The inclusion of the effect of the monsoon season turned out to be quite significant to this mines operations.

Please do not assume anything like operating hours per annum when designing a materials handling system. It involves alot of capital which you could easily loose, so it must be done properly.

Regards

LSL Tekpro ■

Mr Graham Spriggs

How can i get hold of your paper. I need to clculate the same on Ash and coal conveyors and i think that reading your paper might help me a lot.

Regards ■

The paper is too large to e-mail, but they tell me it will be published in Bulk Solids sometime soon.

Otherwise I can fax a copy, if you send details to gspriggs@global.co.za

LSL Tekpro ■