Cost-efficient high-capacity material transport over difficult terrain

30th May 2008 By: Darren Parker

In August 2007, shortly after category-four Hurricane Dean ravaged the Caribbean island of Jamaica, with winds of up to 249 km/h, conveyance specialist Doppelmayr Transport Technology handed over Mt Olyphant, its biggest RopeCon system yet, to bauxite mining company Jamalco/Alcoa.

The system withstood this crucial test virtually unharmed and was back in operation as soon as the necessary safety checks had been carried out. Doppelmayr Transport Technology MD Hermann Frühstück reports that nine months later, the system remains unaffected by the challenging weather and is working well.

In December 2004, Doppelmayr was consulted on behalf of Jamalco/Alcoa, which was looking for a material transport system to link its new South Manchester mine with St Jago. Jamalco/Alcoa required that design measures be taken to ensure a trouble-free transport of bauxite, a sticky material prone to caking when transported on conventional conveyor belts. The new system needed to prevent dust dispersion and have a quieter operation, while offering reduced operational and maintenance costs and enhanced security.

In 2005, Jamalco/Alcoa visited the RopeCon installations in Austria and when Doppelmayr was awarded the contract in December 2005, its scope of delivery covered engineering, equipment supply, assembly and site training. The equipment was shipped to Jamaica from Europe in its entirety, along with the special tools required for the pulling of the ropes, which alone filled 14 containers. Meanwhile, the belt was dispatched in twenty-one 1 010-mm containers and vulcanised on site. The track ropes came on six reels, two of which weighed about 86 t each.

Doppelmayr set up a project development team at its headquarters in Wolfurt, Austria, as well as a project coordination team on site, in Jamaica. The assembly team dispatched to Jamaica was assisted by local aid provided by a contractor of Jamalco/Alcoa, which was also responsible for the exact survey of the line and all civil works.

With a total length of 3,4 km and a vertical descent of 470 m, the Mt Olyphant RopeCon integrates the world’s largest flat belt with corru- gated side walls, in terms of length and tensile strength. Frühstück says that the occasional tropical thunderstorm and a couple of power outage disruptions were the only major obstacles he and his team encountered.

“We believe that our system represents the optimum solution for Jamalco/Alcoa’s requirements, and, in terms of environmental sustainability, we have been able to exceed our client’s expectations: not only were we able to decrease space requirements and save 1 200 truck journeys a day along with the associated emissions of carbon dioxide and fine dust, but owing to the specific topographical situation at Mt Olyphant, the RopeCon generates about 1 300 kW/h of braking energy, which is fed back into the power network,” says Frühstück.

He adds that the RopeCon, in Jamaica, is the first to transport bauxite, but that there have been several RopeCon systems built before, which transport different materials, such as wood chips, quartz and inert material.

“We believe the quality and attention to detail of this total system is extremely good. The Doppelmayr employees on site have provided focus and determination through numerous power outages and Hurricane Dean disruptions to achieve this. “It is really to their credit that we now see a world-class, first-of-its-kind system, of which we all can be very proud,” says Alcoa mine project manager David Ritchey.

RopeCon is a bulk material and unit load handling conveyor, which combines the benefits of well-proven ropeway technology with those of a conventional conveyor belt. It is quiet in operation and prevents dust dispersion while offering reduced operational and maintenance costs.

The overhead conveyance system operates completely off the ground and consists of a belt with corrugated side walls and integrated wheel sets that run on fixed anchored track ropes, guided over tower structures. This decreases space requirements and easily crosses buildings, roads, rivers and other obstacles.

The hauling function is performed by the belt and, with the wheel sets integrated in the belt, virtually all mechanical equipment returns to the station where it can be easily and economically maintained. Travelling along the track ropes on wheels, the belt is not subject to flexing and so wear on the belt is reduced as much as possible while the material is stationary on the belt. This has proven greatly beneficial with regard to the properties of the material.

After the material has been discharged, the belt is turned soiled-side-up to decrease the dispersion of residual material and dust.

Austrian company Lenzing, an expert in cellulose fibre technology, relies on RopeCon technology to transport wood chips from the storage area to the processing plant. The material transport system is required to cross existing plants and conveyor systems, a river and several roads with minimum use of tower structures. In the case of Lenzing, the RopeCon was designed to guarantee 100% availability at wind speeds of up to 130 km/h.

Austrian Ramsau quarry operator Hans Zöchling was the first RopeCon operator to benefit from the topographical situation at the quarry. As in Jamaica, the RopeCon system at Ramsau actually generates power from braking energy, which is used to operate the crushers and other equipment. The quarry operator was awarded the Austrian ‘Klima:aktiv’ award for an active contribution to preserving the environment.

Recent contracts have been awarded to build a RopeCon system in Papua New Guinea (PNG) and the Sudan. The system in PNG is currently being assembled and will transport gold ore over a distance of 2,7 km. Just three support towers over the entire length are needed.

The Sudan project services the cement industry, transporting limestone over a distance of 3,5 km and crossing the river Nile with a rope span of 850 m. The equipment for the project is currently being delivered and construction is scheduled to start soon.