Design Improvements for Draglines

The digging end of the dragline, the bucket, continues to evolve as various aspects of it are optimized. Recently, Weir ESCO launched the ProFill Delta design, which incorporates a rear taper feature that allows for simplification of the rigging package. Although this design approach has been on the market in various permutations over the years, the ProFill Delta takes this concept a step further by incorporating design elements from the standard ProFill model, which have proven over time to increase mine production and reduce unplanned downtime. Some of those differentiating elements include the use of high quality cast structural components, highly optimized bucket ratios, and mechanically attached upper wing shrouds to complement Esco’s Nemisys lip and Ground Engaging Tools (GET) system.

In terms of the design process, advanced simulation tools, such as the Discrete Element Method and Multi-Body Dynamic simulation software, provide the ability to achieve a much deeper understanding of bucket loading and response. These tools provide a means to rapidly iterate on various design options to quickly arrive at optimal solutions, and deliver a more efficient experimentation domain than physical testing.

“One of the things that sets the ProFill bucket apart from its competitors is its patented geometry,” said Shawn McCullum, technical product manager for Weir ESCO. “Developed through extensive scale model testing and field validation, the ProFill delivers faster cycle times and higher fill factors than alternatives in the market. An additional advantage the ProFill geometry provides is predictability. Some buckets in the market rely in heaping to produce the target payload. While this can certainly be an efficient approach, it can also introduce payload variability and can risk damage to the machine due to overload. The steady production levels of the ProFill make it easier to balance of maximizing payload, while adhering to load limits, and avoiding structural problems on the machine.”

Another feature that sets the ProFill bucket apart is the bucket structure. The use of high strength castings throughout the bucket provides a strong, durable structure that stands up to the toughest applications, while optimizing material placement to minimize bucket weight, McCullum explained. The use of proprietary alloys developed over Weir ESCO’s 100-plus-year history deliver an optimal balance of strength, wear resistance, and toughness to ensure that these valuable assets continue to produce for many years to come. “One element Weir ESCO has worked to avoid is the use of plate, rather than castings, for critical structural components,”  McCullum said. “Plate structures can be more economical to produce, but lead to more frequent repairs and higher maintenance costs over the life of the bucket.”

The degree of customization for each mine also separates the ProFill from its competitors. Each ProFill bucket is custom designed for the mine in which it will work. Some products in the market take a stock bucket approach, and utilize the same front end ring for a wide variety of capacities. While this is efficient from a manufacturing standpoint, this may not result in a productive, high performing overall bucket geometry.

The versatility of the ProFill design also separates it from its competitors. Weir ESCO has produced ProFill buckets in a wide range of capacities from 32 yd³ (24 m³) up to a 164 yd³ (125 m³) bucket currently in production, which will be the largest operating dragline bucket in the world.

Advances with Bucket GET

The ground-engaging tools (GET) for dragline buckets have also advanced significantly over the years. “Weir ESCO has secured its position as the world’s leading independent supplier of mining GET by continuing to advance the state of the art when it comes to point design, locking systems and alloy development,” McCullum said. “This commitment to the continuous improvement of its systems to deliver optimal performance, reliability and safety has led to Weir ESCO’s Nemisys system to be installed on more than 1,000 machines world-wide. A recent example of Weir ESCO delivering increased value to its end user comes in the area of lock design.” As one of the early pioneers in “hammerless” locking systems, Weir ESCO has continued to invest in optimizing and refining its locking and retention technologies, he explained. 

The Nemisys safety lock, which had already developed a reputation for best-in-class retention reliability and ease-of-use, was recently upgraded to include top and bottom o-ring seals which help ensure safe, easy removal even in environments with heavy fines, excessive moisture, or other factors that can impact component removal. This commitment to provide a combination of ease of use and retention reliability allows Weir ESCO’s customers in all applications to keep their machines digging, their employees working safer and
GET securely on the lip.

Wear packages have also changed in a number of ways. In the interest of safety, wear packages are migrating from large sheets of wear material to smaller sections. “This reduces the risk in handling during both installation and removal,” McCullum said. “This also enables targeted replacement of smaller sections in high wear areas. The other change is in the degree of customization. Weir ESCO works closely with each customer to tailor their wear protection based on digging conditions at the mine. We have a variety of options to draw on including traditional wear plate, clad plate, bi-metallic blocks/buttons, as well as UHMW liners to reduce carryback and filling friction.”

Dragline tooth life can vary greatly depending on factors such as: the machine/bucket/lip system size, tooth style, geographic location, blasting practices of the mine, and whether or not the mine is running overlaid teeth.

Bucket Rigging Systems

Dragline rigging systems have changed in several ways. First, the weight of rigging packages have been reduced, which lowers the overall suspended load and increases payload and production.

The other change is in lock/retention systems, McCullum explained. “The market is moving to safer, hammerless and hot work-free retention systems,” he said. “While there are a number of hammerless and hot work-free retention systems in the market, there is still significant room for improvement in reliability.”

Both of these changes have resulted in innovations to traditional rigging components. “One way that Weir ESCO is responding to these needs is with the development of a new rigging product line, ProSeries Rigging,” McCullum said. “ProSeries Rigging components will deliver significant weight reduction over available products in the market, and the proven retention reliability offered by our Nemisys locking system.”

These changes were brought about by the need to improve productivity, efficiency and safety.  As mines are seeking opportunities to maximize production, all opportunities for weight reduction are on the table. Less rigging weight means more payload that can be moved within machine limits. With worker safety at the forefront for Weir ESCO and the mines, the need to provide a zero-harm solution is paramount, McCullum explained. This shift will lead to improved changeout times, in addition to keeping mine personnel safer at work. These changes were also driven by advances in the tools that our engineers have at their disposal, such as Multi-Body Dynamic simulation tools, which enable more complete analyses than were achievable in the past. Lastly, these changes were brought about by a greater focus on sustainability. Lighter-weight rigging designs allow us to manufacture parts using less metal and less energy.

Service Intervals

The maintenance philosophy of each mine determines bucket repair/replacement timelines. If the mine conducts regular, proactive maintenance, a bucket can remain in service for a long period of time and last a long time. Some mines run ESCO buckets for 18 months at a time and many operating Weir ESCO dragline buckets have been in service for over 20 years.

To determine the time to pull a bucket for repair, visual inspection is the fastest, easiest approach, but other methods can be employed to assess service schedules, McCullum explained. The use of ultrasonic thickness gauges coupled with bucket maps can be used to track wall and other key areas for thickness degradation and component wear. Tracking can also help a mine optimize placement of wear material to maximize bucket life while reducing overall weight and reducing total suspended load.

The decision to repair versus replace is complex and based on site-specific capital hurdles, ROI analysis and cash availability.

“On pure like-for-like bucket replacement, many mines have thresholds where a new bucket is purchased when the projected cost of repair exceeds a certain value of a new bucket cost,” McCullum said. “The ongoing maintenance costs of an ESCO ProFill bucket tend to be lower than market alternatives. Based on ROI analyses that Weir ESCO has conducted, mines will come out ahead by purchasing a long-lasting, quality bucket, rather than purchasing a cheaper alternative, which will be less expensive at the time of purchase, but can cost the mine much more in maintenance costs over the life of the bucket.”

However, miners are very sophisticated today and production outcomes play a large factor in bucket purchases, McCullum explained. “Since we are always optimizing our buckets and improving performance outcomes, incremental production gains can lead to shorter payback periods that quickly justify new bucket purchases,” he said.

Draglines are really interesting mining machines. “Having produced dragline buckets and rigging for over 90 years, and having produced more than 8700 dragline buckets during that time, we are continually learning,” he said. “Learning and innovation are the most exciting part of this product.”

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WireCo Introduces Union Gladiator Pendants for Improved Mining Operations

The Union Gladiator pendants have been designed to improve the service life of shovels and draglines by 10 to 15 times over traditional technologies. WireCo’s Union brand is for delivering exceptional rope quality and outstanding performance and the Gladiator pendants are made with synthetic fibers, which significantly increase the service life by absorbing loads and reducing vibration.

“I am excited to participate in the release of this groundbreaking product that is a testament to our organization’s strength in both the surface mining application and synthetic rope capabilities,” said Dustin Dunning, senior vice president of global energy and mining for WireCo. “Gladiator is a true technology step change for our customers who are looking to lower HS&E risks while also improving operating costs of their mining fleets.”

Surface mining is among the most punishing environments for ropes and boom pendants on the planet. To transmit raw power into cubic yards moved, the entire rope system must be rugged and reliable. For decades, customers have relied on steel pendants to consistently deliver outstanding performance. Gladiator pendants could improve that performance with innovative design. 

“Compared to conventional steel pendants, Gladiator’s synthetic aramid fibers act like a shock absorber during digging operations, reducing fatigue-related issues for both the shovel and the people operating them,” Dunning said. “As surface mining continues to take the lead in meeting the world’s current and future energy needs, the Gladiator synthetic boom pendant is just another example of how WireCo is leading the rope industry through novel innovation and forward-thinking products.”

WireCo is introducing a full line of Union Synthetic Mining Rope Solutions, including Gladiator main boom synthetic penfdants and ARA-Boom aramid fiber mid-boom synthetic pendants, which significantly increase the service life for shovels and draglines by absorbing loads and reducing vibration.

WireCo’s new Gladiator Cable main boom pendants include more than just ordinary sockets and rope fibers. Key elements of the new product lines include:

New patent-pending Uni-HatchT Inspection Port: Tool-less inspectability — opens without the need for tools during routine inspections and features the measurement device embedded in the socket.

Eco-Friendly: The pendant ropes used in the Union synthetic mining rope solutions are fully recyclable. The aramid fibers can be reused in various applications.