There are examples of UG coal mines in Australia with appropriately rated ST conveyor belt. There are also examples of facilities which have ST belting in (or maybe some would consider, potentially) "hazardous" areas (such as reclaim tunnels et al).

The steel cords should be nice and buried in FRAS cover rubber.

I think the concern is generally related with ignition / burning of the rubber rather than the steel cords (potentially contacting something and generating a source of ignition).

Condition monitoring could be implemented to ensure this is maintained, however considering the cost of outages and or capital value of the installation, this would seem prudent regardless.

Regards,

Lyle ■

Thank you for the feedback.

I've contact several belt suppliers and have been told that steel cord is 'very common' in the underground coal mining industry, so long as anti-static & fire-resistant covers are used. There were even suggestions that steel cord belt without the above ratings can be used for surface coal mining.

As Lyle pointed out the concern may be for the rubber cover igniting before the steel cording is even able to cause any damage, which can be minimised with regular monitoring of the coal (dust, temperature etc).

So I think this solves the query

Thank you ■

I know of installations without FRAS covers on "surface" coal conveying. However some of these installations include “potentially hazardous areas”, such as reclaim tunnels (or maybe even enclosed transfer towers)...

Static discharge is a real event and the consequences can be unacceptable.

I guess it depends.

I didn’t notice you are based in Australia.

If you gave a look at Australian Standards on line (assuming you have access) there are standards on FRAS belting (Fire Resistant Anti Static). Unfortunately I don’t have access at this moment, and cant recall the number.

Additionally there are standards on the classification of hazardous areas (i.e. underground coal mines or other areas where hazardous accumulations can occur such as breweries, refineries etc).

It is a bit of a read, and from memory, I think you would need to have significant experience in the field to accurately adopt the hazard ratings in accordance with the, standards, expectations.

If you are interested, have a look on google for coal mining health and safety act, Queensland. I think it specifies that all UG coal belts require FRAS covers. Additionally I *think* (stretching the memory friendship at the moment) is specifies the classifications of Explosion Risk Zones (which is referred to in the hazardous area classification standard).

Regards,

Lyle ■

Nishant - whether the belt is fabric or steel cord is immaterial with the issues that you are considering.

I would expect that the belt that you have is anti-static by default, because of the carbon black loading in the compounding, and that it would meet the requirement that the electrical resistance of the covers does not exceed 300M-Ohm (AS1333.6.7).

I am sure that this could be checked in situ if required (test method AS1334.9).

The same would apply for a fabric belt, but the belt will be the least of your concerns I would expect.

At major coal handling terminals grade M steel cord and fabric belts are used very commonly but it is the situation of the belt conveyor that determines the belts suitability.

You will need to carry out a Risk Assessment. There will be other applicable standards but you would certainly need to review your application to consider the requirements of AS1755 - Conveyors - Safety Requirements. I expect there would also be insurance implications.

You need to consider such factors as the "accummulation of combustible materials". Potential for coal dust etc I expect will be factors. The same would apply for handling grain.

The results of your assessment will confirm whether a standard Grade M belt is acceptable, or whether a fire resistant belt is needed and that could be one from a number of fire resistant belt classifications.

Cheers,

Ray ■

Thank you for the feedback.

Our initial concern was that steel cord belting would be unsuitable for coal conveying, but I am convinced now that provided the correct steps are taken, it is a suitable option.

Another concern was for a steel cord belt, which has been in service for around 40 years conveying various materials in underground tunnels. The question was whether belt degradation and wear could adversely affect its operation once it was switched for coal use. I assume this would be determined during the risk assessment process, combined with the relevant standards relating to combustible dusts.

I appreciate the comments.

Cheers ■

I was assuming that if the belt was suitable for use with the other materials (in terms of its current state of degradation and wear), coal would be no different. Assuming similar troughing profile etc.

There are plenty of people (re companies) who can do scans of the cords (they usually do them whilst they are on a conveyor, I suspect they could be done in a work shop, with the right facilities), which could be an option.

There are repair options for the covers also.

A documented 40 years, sounds like a pretty impressive service.

I guess there are concerns, such as: if it breaks what will happen (especially if there are people around or it is on an incline..). These concerns exist with a new belt, however you have recent manufactures certificates to provide some reassurance.

I guess it comes down to comparing the cost to make yourself happy it is suitable to use (scanning, repair) versus savings over buying a new belt.

You would have to factor in recovery (of the old belt) to the new location also.

The hazardous area classification standard series I referred to previously was AS2430.XX.

Regards,

Lyle

Edit to correct typo / spelling mistakes. ■

Hi Nishant,

The simplest approach will be to simply monitor the internal condition of the steel cords, look for any changes in the splices and track the wear rate on the covers. CBM has been doing this for the last 25 years, so if you'd like some further information our website is www.cbmi.com.au.

Best regards

Stephen ■

Hi everyone,

Thanks for the feedback.

I've been alerted to the issue regarding deck plates and the buildup of material under the idler, but have found it doesnt exist on these particular conveyors.

There was also the concern with sulfuric acid leaching out of the coal but could not find much information to confirm this effect, and whether it would eat away at the rubber covers at all.

I would imagine that if the conveyors will go ahead with coal use, they will be scanned and checked, although just a visual inspection suggested the belts were in good condition (ie. no visible belt problems). Thus it is likely the belts have been replaced one or more times during the last 40 years or so, but cannot confirm how often (or even if) if has occurred.

Thanks Again ■

Hi Nishant,

The issue is sulphuric acid getting through cracks in the rubber cover and attacking the steel cord. Also, visual inspection is ok, but it tells you nothing about the condition of the steel cord (breaks or corrosion) or the splices internally. I would strongly advise that the belt be scanned before use, as more than 10% cord breakage is a serious OH & S issue and will lead to catastrophic belt failure.

Best regards

Stephen ■