By Bill Putnam
By embracing new technology, companies are striving not only to serve their seasoned experts, but also to protect their younger workers and improve their chances of attracting new talent. Today, workers under the age of 30 have been raised around technology, are comfortable with its changing pace, and tend to prefer working with innovative techniques and materials that maximize efficiency. The high-tech rope industry has also participated in this movement by driving the transformation of one fundamental tool—the line.
Specialty rope manufacturers are now venturing below ground to help miners transition from using steel cable to custom-engineered synthetic rope for some of their most crucial tasks. Mining is one of the highest-stake tasks rope technology can be applied to, so it’s been one that the industry’s engineers have taken up with vigor. As a result, synthetic mining cables have been developed that enhance occupational safety for the underground miner. Aside from the intrigue of a good challenge, there are a few other reasons why the synthetic rope industry felt the need to apply application-specific technology to the world of longwall mining.
| Cable Breaking Strength and Weight | ||||
| Diameter (inches) | Breaking Strength (lb) | Weight (lb per 100 ft) | ||
| Cat’s Eye | Wire Rope* | Cat’s Eye | Wire Rope* | |
| 1/2 | 37,400 | 26,600 | 6.2 | 46 |
| 9/16 | 45,000 | 33,600 | 7.5 | 59 |
| 5/8 | 53,000 | 41,200 | 9.5 | 72 |
| 3/4 | 75,000 | 58,800 | 13.5 | 104 |
| 7/8 | 98,000 | 79,600 | 19.5 | 142 |
| 1 | 120,000 | 103,400 | 23.5 | 185 |
| 1-1/8 | 148,000 | 130,000 | 32.0 | 234 |
| 1-1/4 | 172,000 | 159,800 | 38.0 | 289 |
| 1-1/2 | 230,000 | 228,000 | 57.0 | 416 |
| 1-5/8 | 285,000 | 264,000 | 65.0 | 488 |
| 1-3/4 | 330,000 | 306,000 | 78.0 | 567 |
| *Wire Rope – Extra improved plow steel with IWRC core. | ||||
Ergonomic Advantages
Mining is a physically demanding trade, and with the average age of underground miners on the rise, companies are smart to do everything they can to take care of their most irreplaceable assets—their people. It is from that mentality that a trend toward more ergonomic products and tools has emerged. It would not come as a surprise to anyone in the field that back injuries in particular are the most common—and most costly—musculoskeletal injury in mining, comprising 31% of claims in a 10-year study conducted by the Mine Safety and Health Administration (MSHA).
Choosing the right task-specific cable system can have a huge impact on ergonomics, particularly with regard to the weight and flexibility of cables hauled and manipulated by workers. When it comes to weight, synthetic rope offers an undeniable advantage. Synthetic ropes are eight times lighter than traditional wire rope, meaning that a 100-lb load of wire-based cable could be reduced to 12.5 lb of synthetic rope, without any loss of functionality or breaking strength. In terms of flexibility, the fibers used in synthetic mining-specific ropes are extremely forgiving and lend distinctly better bend-over-sheave cycling capabilities than their steel counterparts. And with zero water absorption, these ropes are able to maintain their flexibility even in freezing conditions. These factors alleviate the conditions that lead to many lower back ailments, and help keep workers safe, healthy and productive.
Reduced Time Spent in the Danger Zone
Despite increased use of machinery for the most dangerous parts of a mining expedition, the task of moving a 20- to 30-ton hydraulic shield is still one precarious task in which miners must play the principal role, and in doing so expose themselves to a high level of risk. Since this work involves venturing into an unprotected area where an unpredictable gob edge could collapse, the goal is to keep the miner’s window of exposure as short as possible. But in confined, dim conditions, the process of finding and attaching the clevis can be significantly prolonged by the weight of traditional material.
The synthetics industry saw this process as an opportunity to create a better system. In instances like these, lightweight synthetic ropes provide a distinct safety advantage over traditional wire. Lightweight synthetics allow miners to work with maximum speed and agility as they complete this dangerous task. The faster the rope is transported and hooked to the shield and retriever, the sooner the worker can exit the danger zone and the extraction process can resume, minimizing exposure to the gob edge and saving critical extraction time.
Enhanced Visibility
The lack of light underground impairs visibility levels and poses an increased occupational safety risk among miners. Most people experience vision changes with age, with the most typical changes involving difficulty adapting to the dark and decreased peripheral vision. This sensorial change amplifies the danger of trip hazards and other threats posed by steel lines, which can camouflage themselves against a dark backdrop. Yale Cordage has addressed this problem with its Cat’s Eye reflective rope, which is enhanced with luminous reflective strands and has bright yellow pigmented coating. The custom nature of synthetic rope allows end users the flexibility to tailor color and reflectiveness to their needs, in this case, resulting in a product that enhances visibility in a way that steel products simply cannot.
Stronger & Safer
Today’s synthetic cables are durable enough to reliably stand up to a 98,000-lb break strength as opposed to the 79,600-lb break strength of their steel cable counterparts of the same diameter. Additionally, the ability to twist synthetic filaments both clockwise and counter-clockwise prior to the braiding process results in superior torque balance, as well as low stretch and low elasticity, which in turn reduces risks upon breakage and recoil. And unlike its steel counterpart, users do not have to be concerned with broken wire strands that can result in puncture wounds.
Beyond strength, weight and flexibility, perhaps one of the most important properties of a mining rope is its resistance to abrasion—the ability to withstand prolonged exposure to rough or corrosive underground conditions. Advanced urethane technology answers that need with unprecedented levels of toughness and dependability in even the most hostile environments. Finally, the zero water-absorption feature available in synthetic rope provides assurance that the product will not be weakened by rust in damp underground conditions.
Considerable Cost Savings
By reducing the time spent in the shield-hauling process, the small change to synthetic rope can offer mining companies extra productivity and quantifiable increases in profit. When equipment is easier to see and handle, and is carefully engineered for ergonomic benefits, the cost of workplace injury is likely to decline.
The MSHA study, which analyzed injury claims between 1994 and 2005, found that back injuries cost the industry more than $460.9 million in direct costs over that 10-year period. This figure did not include the cost of lost productivity or training new workers, etc., which they estimated could double or triple the expense. Also notably mentioned in the report was an anecdotal reference to unreported injuries, which the researchers suspected were common and had a noticeable impact on productivity.
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.
While it is critical for companies to innovate to keep pace with an ever-changing and competitive mining industry, it is also true that in an occupation like longwall mining where safety relies on proficient use of familiar materials, workers are reluctant to embrace major changes in the tools they use. The transition from wire cable to synthetic rope does not have to be an arduous one. On all counts, synthetics have evolved to meet and exceed the mining industry’s rigorous safety standards.
Putnam is president of Yale Cordage. www.yalecordage.com
