Published in the September 2007 Australia’s Mining Monthly
SYDNEY-based materials handling company RJ Cox Engineering is looking north to Newcastle, where the company has submitted proposals to companies involved in transferring coal to take up its conveyor belt tear and rip detector system.
Cox Engineering distributes conveyor products manufactured by Unites States company Arch Environmental Equipment, which Cox Engineering managing director Richard Cox believes is the best product available for detecting spills and repairs.
The product is already in use at BHP Billiton's Olympic Dam mine in South Australia and it is understood Port Waratah Coal Services is considering using the system at its Carrington and Kooragang terminals in Newcastle.
Splitting and tearing in conveyor belts has always been a problem, particularly when it comes to dealing with heavy duty material. Being slow to detect belt damage increases wear on the conveyor system due to spillage, and cleaning up the mess is time consuming.
With the Arch system, a tear in the edge or the centre of the belt, or a torn piece of the belt that hangs more than 60mm, will make contact with the system's profiled arm mounted below the belt, and trip the switch to shut the conveyor down.
This also happens if the belt becomes loose or misaligned.
"The detector has an oscillating free tray underneath and if anything hits it, it will knock it out of the way and hit a switch," Cox said.
Each system is designed specifically for each belt it operates on and the switch structure is designed to minimise material build-up, which could render it inoperable.
Another detector system also manufactured by Arch incorporates a network of infrared sensors mounted beneath the troughing belt.
If material penetrates the belt, it falls through the split on to the detector's tray. As material builds up, the infrared beams are blocked and the conveyor is stopped.
A "wash" cycle allows the unit to be cleaned without stopping the conveyor belt.
Cox said there were many hazards and delays associated with spillage from belt splits and tears.
"Spillage can fall back on to the return belt and builds up at the tail pulley," he said.
"It depends if you have a vertical take-up or gravity take-up on the conveyor system.
"If they don't have a V-plough before vertical take-up, it means all material is then going to go down around the pulley on the vertical take-up and it creates a lot of mess around the conveyor, causing undue stoppages.
"What usually happens is if you don't have any protection it means that the build-up is going to cause other problems. For instance it can bury a tail pulley before its detected, especially if it's running 24 hours a day, seven days a week.
"Unless they know there is a problem, there is usually some other damage caused if it continues to operate. If that doesn't occur, it still means you have a crew cleaning up around it; you've got to get someone to go down and shovel the spilt material out of the way.
"If it's an overhead conveyor, you can get material falling and building up in the structure under the belt, which aggravates the operation of the belt conveyor."
Cox Engineering also supplies a heavy duty belt scraper, the Gordon Super Saber Cleaner, which is designed with a polyurethane blade on a shock absorbing mount that withstands the tougher materials that would normally destroy belt cleaners.
"It's for pulleys in excess of 1-1.5 metres in diameter," Cox said. "It has a segmented blade system, which means because of the size of it, you can replace the damaged section; for instance when one section wears more than another, you can remove it.
"The polyurethane is poured into individual moulds, it's cured and then it's autoclaved to give it high wear resistance. In heavy applications, the blades are applied to the width of the product being carried on the belt, not the width of the belt.
"This is due to the fact that the blades wear in the centre if they are not allowed to sit in the crown of the pulley and, as such, because of their wear characteristics, they require to have product running past the blade so it wears in to suit the profile.
"If you have a full width blade with no product going past it, it doesn't wear and therefore the centre gets worn in the blade. It has a dual primary, where they fit the two saber blades within the one quadrant of the pulley. The first blade is the width of the product plus 50 millimetres and the second blade is required as a clean-up blade to go the full width of the belt."