Downtime on any system has an opportunity cost, but on high-capacity systems this effect is even more pronounced. Engineers from Kinder Australia explain how businesses can tackle this major conveyor problem.
Premature conveyor belt wear, specifically grooving in the top cover at the skirt line, is one of the biggest issues for high speed conveyors .
Conveyor belts, are the most expensive for many sites, are often frequently replaced – especially in high-capacity applications.
Cameron Portelli, Senior Mechanical Engineer and head of Kinder Australia’s engineering team, says when higher-capacity belts require downtime, the costs increase due to the lost opportunity.
“This is particularly true at the ports where a ship needs to be filled in the shortest period to minimise stationary time,” he says.
“The high-speed volume stream creates an enormous amount of friction on hard-skirts, liners, external skirts, the impact support zone and belt cleaners. Our international partners in South America are constantly having conventional products that last a matter of days on high-capacity systems replaced with their line of products in order to extend the clients shut cycle.
High volume streams of bulk materials, not the skirting products, are often the culprit for this high rate of wear in most cases. When fines leak under the hard skirts, they enter the cavity, bulge the soft skirts creating sticky abrasive clumps that remain static and rub against the top cover of the conveyor belt. The belt is then continually subjected to this abrasive build up, which subsequently creates the unwanted grooves. As the grooves become deeper, the issue compounds as more material is allowed to escape under the hard skirts.
Some operations have trialled the removal of soft skirts, some have lifted the hard skirts, others have made repairs on the fly at slow speed.
Yet, according to Charles Pratt, Operations Manager at Kinder Australia none using these methods have eliminated the costly belt damage that ultimately leads to replacement of the conveyor belt.
“The problem unfortunately doesn’t stop there, as the grooves in the conveyor belt cause enormous amounts of carry back (material that fails to be cleaned off at the discharge end of a conveyor by the belt cleaners),” Pratt says.
“Conventional belt cleaner blades are not flexible enough to allow the appropriate penetration of these grooves, whereby the material left in these grooves, then leads to premature idler wear, spillage under return rollers and poor belt tracking. So, the cost of the new conveyor belt is just one negative downside to what is a major problem that causes so much damage and unnecessary waste of resources.
“There is light at the end of the skirted tunnel though, as what has been proven to reduce or eliminate the costly wear on conveyor belt, is simply keeping the transfer point clean and free of material build up.”
Doing so is easier said than done, often due to the guarding in place, reduced number of maintenance opportunities and lack of automated cleaning products available for conveyor transfer points.
However, the combination of a high-pressure water spray combined with the low friction, engineered self-adjusting polyurethane soft skirting, allows for programmed automated cleaning which cleans away the sticky abrasive clumps previously causing the conveyor belt top cover damage.
Idler / roller profile alignment
Proper alignment of impact idlers in conveyor transfer points is extremely important.
Due to the initial tolerance of supplied idler frames, coupled with the harsh wear and tear of components installed in these areas, an uneven belt profile is often present, which makes it difficult for the skirts to do their job and prevent spillage, let alone prevent conveyor skirt grooving.
Pratt says to reduce the concentrated grooving caused by turbulent material and or dust sandwiched between the skirting material and your conveyor belt, the orientation of chute and skirting parts should ideally not be parallel to the conveyor belts running direction.
“This offset or bias orientation will help significantly to aid material flow when exiting the chute, and importantly spread the unwanted damage to your conveyor belt over a larger cross-sectional area, thus extending the life of your belt,” he says.
“The time it takes for the grooves to appear in your conveyor belt is exponentially proportionate to the offset bias in your chute or skirting alignment.
For example, if your skirting material is 12 millimetres thick, and the offset distance is just six millimetres from the beginning and end of the skirted section, you will find that any groove damage should decrease by more than just 50 per cent.
“Providing an even or flat surface for the conveyor belt to be supported in the loading or transfer point, is paramount in reducing the amount of fugitive material escaping under the hard and soft skirts.”
One of the products Kinder manufactures is the K-Shield Dynamax Impact idler, which is suited for heavy duty and high-capacity applications. It consists of a dual trough roll configuration matching the existing trough profile, to provide a uniform cross-section while maximising the overall loading capacity of the system.
K-Shield Dynamax Impact Idlers are suspended above anti vibration/spring element mounts, providing maximum cushioning and absorption of the conveyed materials impact. For maintenance purposes, the idler frame system also features an additional jack down/lowering access facility. This allows rollers to be easily and efficiently replaced within the high-impact loading points.
Pratt says there is no quick fix to conveyor belt wear, calling it a massive issue that plagues the global mining, export and processing industries.
“Instead, there are many improvements required by sites to reduce or eliminate the grooving in conveyor belts caused by transfer points,” he says.
“The most important first step a site must take though, is to stop accepting the problem and thinking it can’t be solved.”
Article courtesy ABHR.