[QUOTE:

To the best of my knowledge, the this cover grade is effective in minimising operating power consumption in HORIZONTAL conveyors and not in INCLINED conveyors wherein the power consumed to raise the load is too predominant for there to be any significant advantage gained out of using a belt with LRR back covers.

I would also like to know if a LRR belt should at all be employed in a DOWNHILL conveyor. If not, why not & if yes, why ?

Looking forward to answers from forum experts.

Regards

BoL[/QUOTE]

What is the percentage of power saving is expected compared to that of conventional belts?

Regards, ■

In General terms, LRR rubber lowers the rolling resistance about 0.4%. So, from a 1.5% rolling loss you may reduce this to about 1.1%. The loss is for belt losses with constitute about 75% of all losses. Thus, the reduction in rolling loss is about 27%.

When the belt inclines or declines, the frictional difference remains the same. If a belt inclines 10 degrees, this equates to 17.6 % slope. The gain or loss on the 10 degree slope is still about +/- 0.4% of the +/- 17.6 % change in slope for a 10 degree slope or about 2% gain.

Please note: some belt manufacturers are full of "baffle-gab". They say they have Low Rolling Resistance (LRR) rubbers but the performance they install does not. I have witnessed this on multiple projects. One example: Belt is installed in 1990 that achieves LRR status that transports 2800 t/h. With planned speed increase and new power old belt could do better than 3000 t/h. An SLRR belt could do 3500 t/h. Client buys LRR belt from Baffle Gabber. Then belt produced 2200 t/h. Client is in disbelief - hires reputable firm from Europe to investigate, at great expense. Also sends rubber sample for CDI testing. Test results show 2200 t/h. Europeans say its something else but not sure. However, they cannot explain that only by changing belt production drops 27%. Hmmm?

There are also belts that produce greater gains than the above. Some are called Super Low Rolling Resistance (SLRR). These can improve rolling losses as large as 50% or more. You must also be cognizant of belt cover thickness, belt speed, idler roll diameter, idler spacing, trough angle, bearing series and type of grease, operating temperature, and percent material loading. These are the fundamentals.

There are other factors that can alter the above including: belt fabric reinforcements, vertical and horizontal curves, belt turnovers, steel cord diameter and pitch, to name a few more complications.

Future gains may improve rolling resistance by another 15-20% over SLRR. These are in research and will be available for use in about one year.

Final Two Words: 1) Beware of charlatans. Some belt manufacturers have no scruples and just plain lie, and 2) Take care that belt bottom cover surface press does not exceed allowed belt properties and cause divots or pitting under cables at the high stress zones as has happened on some long overlands.

We are available to assist with these design criterion. ■

There is not such thing as conventional belts. It depends on who you buy the belt from - reputable or junk dealer.

Junk dealers sell belt based on price. These belts are filled with literal junk. Material that is cheap and acts as a bulking agent - increase volume but does not decrease tensile and abrasion resistance in a major way. The junk does however substantially reduce the viscoelastic damping or hysteresis with clays and ash and non-binding oils.

The junk costs about 10-20% of the proper carbon, silicon fillers with proper coupling agents, or improved polymers of today. THus, the belt price is better, but, the hysteresis can be 20-50% more than a good NR (Natural Rubber) belt.

Buyer beware of cheap belts. The power loss can equal the total cost of a conveyor system when evaluated over a 20 year life cycle period.

Most owners are not aware of the tremendous loss of revenue. So long as there is sufficient power everything is OK.

We worked on a 15 km project where the client changed the belt 2010. We told the client a year ago, after testing the belt, he could obtain a 50% reduction in power or 100% increase in production. A year later, purchasing agent buys the junk belt, judged on price. Another opportunity lost. ■

The question is can the user/owner make use of the regenerative power? Where power is at a premium, higher regenerative power lowers cost of transport. Thus, regenerative conveyors are ususally in demand. They run the many other operations of the mine.

Where there is no benefit to power regeneration, then higher rolling resistance belts are selected. This is seldom the case. ■

Dear Mr.Nordell,

Is there any standards or testing available to differentiate between good seller and a bad seller while selecting LRR belts?

Thanks & Regards, ■

Dear Spanesh,

You have obviously not been on CDI web site. Please do so and look in Innovations. On right side of page you will see a list. Top of list is Power Analysis. Go to and look at slide 11. Here you see: 1) explanation of power loss in rubbers, and 2) comparisons of 24 rubber bottom cover compounds with varying kW vs. Temp. performance properties.

We do measure all rubbers from around the world from all manufacturers. The rubbers are classified according to their power vs temperature performance on a Benchmark conveyor where all idler drag and parasitic losses have been removed. We and others have also published performance of rubbers on many of the long overland conveyors designed by CDI. Please read and then ask your questions left unanswered.

Note, performance varies with manufacturer's by more than 100% when comparing best to worst, and more than 150% when comparing one compound's variation from warm to coldest temperature extremes.

Different conveyor designs yied different results. Larger conveyors typically are more sensitive to power variations as are pipe conveyors. ■