2.5-km, $65 conveyor belt key to Highland Valley transformation

Visitors travelling the Highland Valley highway at Logan Lake, B.C., last year must have wondered what was going on at the Highland Valley Copper mine site. Slowly taking shape, like some ancient Egyptian earthwork, was a gigantic ramp stretching almost as far as the eye could see. When it had stopped growing in May, and was ready for the next phase of construction, it was 2.5 km long.

The ramp is actually a $62-million state-of-the-art belt conveyor and crusher system, one of the most impressive in the world. It is designed to transport ore from the open pit mine to the mill. Mining engineers from Chile, People’s Republic of China, Japan and Australia have already visited the site to inspect it during construction and mine staff are expecting more visitors this year.

When Cominco and Lornex Mining first discussed the feasibility of combining forces early in 1986, one of the major points of the partnership was a mine plan involving a system of in-pit crushers and conveyors which would supply 100% of the ore from the Valley pit for at least five years. The partnership was formed on July 1, 1986, and immediately the plan was put into action.

“One of the major advantages of this system is the reduction on the cost of transporting this ore,” says Phil King- Jones, manager, services. “We just didn’t have enough trucks and equipment to work both the Lornex and Valley pits at full capacity. With the new system we are able to run 6,000 tonnes of ore per hour on each conveyor and because the crushers are right at the Valley pit we have cut back on the long ore hauls to the Lornex crushers.”

Within the Valley pit, two crushers feed their own 152-cm conveyors which deliver the ore to a transfer stockpile outside the ultimate pit limit. At this point the ore is directed to a load-out conveyor for hauling by truck to the Bethlehem mill across the valley and also to the two parallel conveyors which link up with the existing conveyors feeding the Lornex mill. Most of the ore will be conveyed to the Lornex mill with approximately 30,000 tonnes per day directed at the Bethlehem mill.

“The system incorporates a number of important features,” King- Jones says. “The new crushers are semi-mobile. They may be required to be moved as frequently as every six months to one year and each move can be prepared quickly and without need of concrete or other additional structures. Each unit consists of three modules; the apron feed, the crusher, and the discharge belt. All can be disassembled easily and moved by a crawler or multi-wheel transporter deeper into the Valley pit as mining progresses and then the conveyor will be extended as required.”

“The conveyor belting system, a twin-section 2.5 km line, is monitored by consoles located in the pit crusher stations, in the Lornex stationary crusher and in the Lornex mill. These are linked together by a fibre optic `data highway.’ Instruments can detect the temperature of any of the drive motors or pinpoint a rip in any of the belts. If trouble anywhere along the line occurs, the system will automatically shut down.”

A completely new water collection system, built at a cost of $2.7 million, has been installed to deal with ground water seepage into the pit floor as the mine deepens. A $900,000 power distribution system has been installed to handle the increased power requirements for the new conveyor and crusher system. A series of dewatering wells were drilled around the pit rim. The water pumped up to the Lornex mill is to be used in the flotation process.

With this new crushing and conveying system, Highland Valley Copper will increase tonnage mined to 90 million tonnes per year and become the third largest metal mine in the world, just 10 million tonnes behind Palabora of Sou th Africa and 30 million tonnes behind the leader, Chuquicamata of Chile.

From Orbit, Cominco Ltd.’s in- house publication.