The adoption of new technologies is often a long and sometime difficult road, but synthetic pendants are now being seen as a proven technology in dragline operations with a long list of demonstrated benefits. Today, both Synthetic Main and IBS pendants are available through industry rope pendant leader, Bridon-Bekaert The Ropes Group’s Tiger Blue Synthetic Pendant and Applied Fiber’s terminations.
Barry Brennan, Bridon-Bekaert The Ropes Group, recently explained to IM why Tiger Blue Synthetic Pendants are being adopted by global dragline and shovel operators: “Synthetic main support pendants were first discussed for development over 12 years ago. At the time, it was recognised that a reduction in weight aloft could greatly improve dragline performance as it would allow for increased capacity or reduce the working load of the machine. As mine operators are always looking for improvements, these two benefits alone were a strong catalyst to move forward and build the first synthetic main pendants for a dragline.”
The product was first adopted by Cloud Peak Energy, now NTEC. Applied Fiber designed, built, and successfully installed the first set of mains at the Antelope mine in Wyoming over five years ago. While the pendants were originally developed to take advantage of the weight reduction synthetic rope would provide, by increasing production capacity, numerous benefits have been noted beyond the production gains.
“Synthetic pendants are multiple times lighter than steel and reduce sag weight, and this, combined with synthetics natural damping properties, have proven to be a huge benefit as the pendants no longer bounce or ‘jump rope’ like steel does. Formerly, the constant jumping of a large mass of steel also causes the lattice boom to also bounce around, creating all kinds of stresses in the dragline boom structure and throughout the machine. Cyclic fatigue is one of the key contributors to metal cracking and fatigue of the structural components.”
The first set of synthetic mains were installed, and a change was immediately noted. The bounce and jump rope effect were nearly eliminated with the synthetic pendants, and the boom movements were quietened dramatically. This has had a substantial reduction of fatigue and stress on the structural components. The difference between steel and synthetics can not only be seen at a distance but felt by the operators – who comment how much less movement and vibration exist in the cab.
“Over time, it became evident that the machine was seeing less vibration and cyclic fatigue damage. Draglines converted to synthetics were no longer seeing any fatigue cracks or cracking in the boom. A scheduled maintenance outage to weld the boom lacing, was eliminated as the fatigue had been significantly reduced. In time, it was also noted that maintenance crews were not going out and performing welding on the catwalks, railings and the steps on the machine, a constant and accepted maintenance issue at most mines.”
NTEC calculated a conservative week’s worth of added dragline productivity per year as they skipped the outage planned for lacing welding as it was a normal occurrence and part of the maintenance plan. The company has experienced no major welding repairs in the lacing since the installation. This benefit alone was enough to make the change, and no one had even considered this benefit when they were first installed. Since then, all NTEC draglines ready for changeout have been converted to synthetic pendants.
Following years of evaluation, the company owning the largest dragline fleet in the world is making Tiger Blue Synthetic main pendants the go-forward standard product for its fleet. The company has already installed synthetic pendants main and IBS pendants on both Marion and Bucyrus draglines, and they are seeing first-hand the benefits for production and maintenance with the dragline jumping and bouncing reduced significantly.
“Numerous mining machine operating companies are now looking to adopt the proven technology for their draglines as the evidence continues to grow in support of large financial gains with synthetic pendants. More recently, through extended data, it has become clear that synthetic ropes will reduce annual downtime and welding cost and may have a material impact on fatigue life of the boom structure and pendant changeout cycle. This means that the boom is not only anticipated to last longer, but if combined with other activities, it is seen as very possible to push out the outage for boom laydown event. In some cases where other components in the system have been optimised, it is envisioned that a full pendant replacement outage may be skipped.”
The ability to materially shift pendant changeouts is based on the added advantage of synthetic pendant life. One of the goals in developing the synthetic pendants with extended life was based around the development of a monitoring system to continuously gauge the life of the pendants. The synthetic pendants last longer than the steel because it has better fatigue properties than steel strand. Longer pendant life, coupled with this health management capability, allows the mine to safely push out the planned boom laydown to replace the steel pendants. This is a huge production benefit and financial savings for the mine.
While clients first saw the synthetics as a mean to either increase capacity or reduce the welding downtime on an ageing fleet of dragline booms, it has now become clear that there is also the distinct potential to further extend the life of the machines and defer boom laydown events. “This opens the door for yet another wave of financial gains for the operating companies. While there are many benefits, some of the company’s clients are realising this may be the greatest financial benefit in adopting Tiger Blue Synthetic Pendants.”
The maintenance benefits, combined with the production benefits, make it clear that there are many substantial financial gains in switching from steel to synthetics – despite the difference in cost. Putting a damper in the load path makes the dragline runs better.
The innovation has proven out; dragline operators have increased production capacity, reduced machine stress, fatigue and structural cracking, reduced maintenance, increased uptime, and extended the life of major components including the product that was replaced. Additionally, nearly all dragline operators appreciate and comment on the lack of machine vibration.
It was also clear that the product weight and damping benefits would also translate well for shovels. Electric rope shovels and their pendants were in many cases replaced more frequently than dragline pendants primarily because of the frequent shock loading from ‘boom jacking.’ Boom jacking is one of the more violent events that a rope shovel can experience in operation. It occurs when the pendants supporting the boom go slack because of the boom being driven upward by the dipper. When the shovel reengages, the boom drops freely, slamming downward and severely shock-loading the pendant cables and system overall.
While mines always work and train to avoid boom jacking, it is an inevitable part of rope shovel’s operation, and its effects are quite damaging to the machine over time. With Applied Fiber’s modified rope termination, the design creates a shock damping pendant set to reduce the impact of boom jacking and vibration for electric rope shovels. “Installed and running for a few years now the product is proving out, machines run smoother, and the effects of boom jacking are greatly lessened, reducing peak loads from boom jacking up to 52%
“Vibration in the machine is also greatly reduced. Lab testing has shown that synthetics dampen vibration up to 12x more than steel. Vibration is a large cause of maintenance issues on shovels. The operators notice the improvement. They can feel the reduced vibration which causes hand and body fatigue after long shifts working the equipment.”
Bridon says its Tiger Blue Synthetic Pendants help the machines run smoother and more efficiently and is well suited for the hard material digging and rough conditions in oil sands, coal, gold, or copper mines in both cold temperatures of the Canadian oil sands to the hot temperatures of the Australian desert. “Mines worldwide are now making the change to Tiger Blue Synthetic Pendants for more and more critical applications. The high strength synthetics handle fatigue, reduce vibration, and are safer and easier to handle, providing numerous benefits to equipment and their operators.”
