By Bill Putnam
Making the case for modern synthetic over traditional steel rope in mining applications
Mining is a high-stakes, high-risk industry, from occupational hazards to environmental concerns and geological impacts. It is also a highly profitable and absolutely necessary part of the global economy: In the United States alone, the total mineral production value was $74 billion in 2011.1 The industry has been relatively stable in recent years but has also seen fluctuations in demand and material value. To keep up with a sometimes unpredictable market and to prevent complacency, the methods and processes of mineral mining have started to shift to include more advanced technologies, refined tools and a broader awareness of the environmental factors of mining.
Over the last several decades, rope manufacturers have contributed to this evolving industry by improving the line systems used during the mining process, including both above and underground mining. Through sophisticated design and advanced manufacturing, synthetic rope has become an alternative to steel cable, one that is more agile, resistant to the elements and cost-effective. The transition from a steel cable to synthetic rope or synthetic cable is helping to revolutionize the mining industry and products are being developed in conjunction with industry engineers to construct a rope that is innovative, customizable and occupationally consonant.
Advanced Weight Capacities
Steel cable has been the decades-long customary choice due to its ability to lift, hold and transport extreme weight. However, the weight of the steel cable itself adds to the overall load and it is in this aspect that synthetic ropes begin to exhibit clear advantages. Synthetic ropes are seven to 10 times lighter than their steel cable counterparts of the same diameter, and a conversion to synthetics could replace a 100-lb (45-kg) steel cable with 12.5 lb (5.7 kg) of synthetic rope. In addition to its lightweight characteristics, the fibers used in synthetic rope provide maximum flexibility, making their bend-over-sheave cycling capabilities exceptionally better than that of steel cable. A change from steel cable to synthetic rope could lead to a reduction in back injuries—a prevalent health issue among miners—and could potentially increase productivity.
A synthetic rope system has a higher break-strength than a steel cable with an equivalent diameter. The braided ropes used in mining-specific synthetics are inherently torque-balanced and typically these high-strength modern ropes have very low elongation characteristics similar to the steel wire rope they are replacing. These fundamental differences in design remove the possibility of a miner enduring puncture or laceration injuries often attributed to working with aging steel cables.
Throughout the industry, minimizing the time a miner is exposed to dangerous situations is a top priority and selecting the right task-specific cable systems can greatly reduce these exposure times. When working in danger zones, a miner faces unprotected environments—areas that may be compromised or unstable. The use of machinery has alleviated some of the most risky tasks, such as moving a 20- to 30-ton hydraulic shield. Replacing steel cable with a more agile synthetic rope enables a worker to transport the line, hook a walking shield and exit the area more quickly. In instances like these, the lightweight characteristics of synthetic rope provide a distinct safety advantage over traditional wire.
Environmental Exposure Advancements
Perhaps the most important properties of a mining rope, beyond strength, weight and flexibility, are its resistance to abrasion or its ability to withstand prolonged exposure to rough or corrosive underground conditions. Over time, steel cables can become rusted, brittle and can begin to corrode due to exposure to intense weather elements such as heat, cold and moisture. Preventive measures can be taken to protect the steel cables from these elements; i.e., periodic lubrication of the cable to help preserve it. However, modern mining synthetics do not require this maintenance as advanced urethane technology provides unprecedented levels of toughness and dependability in even the most hostile environments. Synthetic rope can be designed to protect against snags and UV exposure, and does not rust. It maintains flexibility in cold temperatures and does not absorb water.
Varieties of rope specifically designed for underground mining can be safety-enhanced with reflective strands and designed to meet specific color needs. The custom nature of synthetic rope allows users to tailor color and reflectiveness to their needs and can improve visibility in a way that steel products simply cannot. Combined, its visibility features and resistance to exposure can help reduce situations that lead to injuries, while keeping workers safe and productive.
Cost Saving through Occupational Safety
A 2005–2007 occupational mining report from the Institute of Occupational Health and Safety Research (IRSST) stated that the average associated costs of injuries for one year of mining was more than $129 million.2 This cost estimate included administrative, legal, recruitment and training costs. As with any occupation, not all injuries are always properly reported, and some are not documented at all, so the total cost could be greater. Overall, however, the metallic and industrial mineral mining industry has seen a significant decrease in mining-related injuries and replacing steel cables with synthetics could continue to support this declining trend in the mining industry.
The U.S. Mine Safety and Health Administration (MSHA) reported that, over the past 20 years, there has been a 69% decrease in injuries associated with metal/non-metal mineral mining.3 Improving upon an element of the mining process that a worker engages with so frequently, like replacing heavy steel cable with lightweight, abrasion-resistant and highly visible synthetic rope, can continue to reduce occupational injuries and their associated costs. Replacing heavy cable with lighter synthetic rope can help mining companies stay productive, decrease their workers’ compensation and insurance claims, and get a handle on the crippling expense of employee injury.
As with any occupational setting, workers who have come to rely upon familiar materials and procedures can be reluctant to a sweeping change in equipment or process. In the case of transitioning from steel cable to synthetic rope, however, the change does not have to be a strenuous or overwhelming task. The technology behind synthetic rope has evolved to exceed the rigorous safety policies and standards of the mining industry, and the relationship between rope manufacturers and mining companies is often a collaborative one. Rope manufacturers can extend specification needs beyond that of a steel cable provider with custom-made design requests including size, weight, color and break strength. The design conversation provides opportunities for collaborative engagement between the manufacturer and the purchaser and can include specific usage guidelines, employee product training, workplace transition and worker confidence.
It is important to note that once the transition has been made and a rope system implemented, the relationship between the mining company and rope manufacturer does not end. Synthetic rope manufacturers and their key distributors have the technology to periodically monitor a rope’s performance and integrity over time by collecting abrasion, strength loss and other data specific to industry use. This information not only provides valuable feedback to the rope manufacturer, but also helps the end user gauge the effectiveness of their materials and compatibility with their workers and environment.
Challenged with increasing margins and efficiencies while reducing injuries, today’s mining companies are continuously reviewing and optimizing their operations. One possible solution to advancing the mineral mining industry is transitioning from steel cable to synthetic rope.
The flexible design characteristics of synthetic rope are unmatched by that of steel cable. Synthetics offer features that increase visibility, reduce breaking and prevent corrosion, while also exceeding ergonomic and occupational safety standards. The rope’s lightweight and forgiving qualities could potentially increase load hauling size, which, in turn, could lead to increased profits and reduced operational costs. Synthetic rope has played a major role in the evolution of the metallic and industrial mineral mining industry and it continues to provide the opportunity for further modernization and profitability.
1. 2012 Mineral Commodity Summary (2012), U.S. Geological Survey.
2. Estimating the Costs of Occupational Injuries, A Feasibility Study in the Mining Industry. (2013). Institute of Occupational Health and Safety Research (IRSST).
3. U.S. Metal-Nonmetal Mining Record of Reduction, Total Injury Rate, 1990-2012, (2012). Mine Safety & Health Administration.
Bill Putnam is president of Yale Cordage, a custom and specialty rope manufacturer based in Saco, Maine, USA.