Rio Tinto's clever coal conveyor touches lightly on the environment as it achieves engineering excellence

Skyline stacker with enclosed road crossing, above left, and  innovative incorporation of of an existing skyline gantry system contained within the new structure, top
Skyline stacker with enclosed road crossing, above left, and innovative incorporation of of an existing skyline gantry system contained within the new structure, top

A 2km coal conveyor system that combines engineering innovation and efficiency with built-in safety and environmental excellence has been completed by the Ellton Group for Rio Tinto Coal Australia's Coal and Allied Hunter Valley Operations.

The 1400 mm belt conveyor system rated at 2400 TH – driven by ground-mounted Bonfiglioli Power Pack drives - includes an overland conveyor and a skyline stacker conveyor system that eliminates the previous need for heavy trucks to transfer coal from another load out facility during peak production.

The unique conveyor design also overcomes numerous environmental and structural challenges as it traverses reclaimed and subsidence-prone land to deliver high volumes of coal to an existing stockpile facility through a cost-efficient design that incorporates recycled previous structures and which was delivered safely and within budget.

New gantry structure encloses existing skyline gantry system
New gantry structure encloses existing skyline gantry system

“One of the many unique aspects of the design was the complete incorporation of an existing skyline gantry system contained within the new structure,” said the Managing Director of the Ellton Group, Mr Mark Elliott.

“The old gantry had a tripper running through it. We built our new, higher capacity structure around the existing tripper gantry, running the conveyor in the opposite direction but sharing a radically improved and strengthened structure that easily and safely handles higher conveyor loadings but is designed to minimize additional mass and wind loadings.

“I think one of things that impressed Rio Tinto was that we didn’t attempt to impose standard solutions on their unique technical and site issues.

Working in consultation with their operations staff and their consultants, we evolved numerous options that made good use of existing infrastructure while observing their rigorous safety and environmental standards. The benefit of this innovative approach was clearly seen in the way in which we repaired and strengthened existing trestlesand piers to withstand new loads, for example, providing a solution for less than half their expected price.

“That’s the sort of thing you can do as a younger, nimble and innovative supplier. While we have had plenty of experience, particularly in the Hunter Valley, we are not bound to old ways of doing things or regimented thinking that says we have to tear down everything that’s already there and start again. As a company committed to efficiency, sustainability and minimising the impact on the environment, I think Rio Tinto were impressed by our close attention to their wishes.

“We certainly had to submit a very competitive tender and pass thorough scrutiny of our credentials and experience, but I believe one of our winning edges was the ability introduce fresh thinking to issues facing mine operators.”

Examples of design, safety and environmental initiatives introduced on the project include:

  • Safe and efficient design of the trestle structures carrying the overland conveyor above extensive areas of reclaimed and previously mined land that is prone to subsidence. The solution included trestle structures and roof sections that were not only structurally independent of each other, but also independently adjustable in three dimensions if and when issues arise.
  • Sound economics as well as a focus on environmental results meant that maximum utilization of existing infrastructure was a prime objective However, wanting to incorporate existing structures in the final design that were not originally rated for the revised duty, was only part of the design challenge. The upgrade works had to occur whilst the existing plant continued to operate so that the new design had to be suitable for construction in and around equipment that could not be stopped or demolished.
  • Minimised additional wind and mass loading on the existing structure was achieved by adopting a “wrap around” gantry design to support the new conveyor and tripper. The gantry design had to be as light as possible and still allow the existing tripper to operate inside the old gantry both during and following construction.

Refurbished and strengthened foundations and structures
Refurbished and strengthened foundations and structures

Extensive environmental protection including civil works and fully enclosed structures
Extensive environmental protection including civil works and fully enclosed structures

  • Extensive containment and protection of the load and environment surrounding it. In addition to full coverage of the conveyed load to minimize spillage and dust, the areas traversed by the overland conveyor are protected by civil works including bunding, side dish drains, channeling and settlement ponds. These works separate and redirect clean water run-off from surrounding landscape to avoid possible contamination and capture water emanating from the conveyor path and directed it to one of several dirty water settlement ponds constructed along the route. By containing run-off and run-on, recycling is optimized and contamination of the environment is avoided.

The fully enclosed overpassing of a public road further enhances community relations
The fully enclosed overpassing of a public road further enhances community relations

  • Recovery and re-use of old gantry structures, which were stripped , refurbished, painted and refitted to new standard and incorporated into the elevated stages of the overland conveyor. In addition to saving money and avoiding waste, the refurbishment and reuse cleaned up the entire site where they were previously located.The fully enclosed tipper feed structure now spans a busy local road, removing the need for trucking by providing a clean and safe alternative.The overpassing of a public road and elimination of truck movements further enhances community relations, which are a high priority of Rio sites.

Bonfiglioli Power Packs being custom engineered in Australia for Ellton
Bonfiglioli Power Packs being custom engineered in Australia for Ellton

  • Use of innovative Bonfiglioli Power Pack heavy duty fully coupled drive combinations, engineered by Bonfiglioli for optimum ease of installation, rugged service and low maintenance in materials handling and process applications.

    "The drives were specified by Bonfiglioli Business Development Manager Mr Kris Jaryn, with whom we have worked well before," said Mr Elliott. "He is a proven performer, and Bonfiglioli is a respected supplier that gave us what we needed, when we needed it to provide on-time performance."

Innovative drive mounting
Innovative drive mounting

  • Mounting of the drives and take ups at ground level, rather than with elevated drives and vertical take-ups, for ease and safety of maintenance. "A problem with off-ground mounting is that access is difficult and it is hard to isolate the belt and remove the energy load from within it.

    "With our on-ground concept, it is simple and safe to detension the belt and remove the stored energy, thus enhancing safety. The hazards associated with isolating suspended gravity weights are removed. The design – which reflects our experience in underground mining – also provides better and quicker access for maintenance," said Mr Elliott.