Following an order placed by Bateman Engineered Technology (BET) in 2011, bulk materials handling company Weba Chute Systems has delivered three transfer chutes to Barrick’s Chimiwungo Development Project (Chimiwungo is one of the two main Lumwana ore deposits along with Malundwe) in Zambia for installation in the raw materials handling section of the plant. Commissioning will take place at the end of the second quarter of 2012. All three chutes will operate on the same line, handling primary crushed ore up to 250 mm with a maximum lump size of 400 mm at an average throughput of 5,140 t/h. The first chute will transfer material from an 1,800 mm wide conveyor at 3.15 m/sec to a 1,350 mm outgoing conveyor at 5.5 m/sec. The second trifurcated chute will move material from here to either of two receiving belts at the same width and speed or bypass to a bin to cater for the feed conveyor coasting time during a power failure or emergency stop.

The third chute will transfer material from the incoming 1,350 mm belt, which it receives at 5.5 m/sec to an outgoing 1,800 mm belt travelling at a speed of 3.17 m/sec. Alwin Nienaber, Weba Chute Systems technical director, says the design of the second chute took into account the client specification that changeover from normal operating conditions to bypass mode must be achieved within 5 seconds. This resulted in a trolley speed of 400 mm per second. “In applications like this where abrasive materials such as copper ore are handled and require regular maintenance as well as planned chute maintenance intervals, Weba Chute Systems are proven to reduce operating costs per tonne,” he says. “This is possible because the chutes not only require substantially less maintenance, but their design also eliminates the downtime associated with conventional chute design and the typical lack of attention traditionally given to transfer points at the plant design stage.”

Weba Chute Systems control the direction, flow and velocity of the calculated volume and type of material in each application, also taking into account belt width, belt speed, material sizes, shape and throughput. “A correct and appropriate chute design is critical and it is imperative that all these factors are taken into account,” Nienaber says. “It’s not just about manufacturing a chute. We look at both current and historical data in order to fully understand exactly what the customer requires. We look at the most important factors that need to be addressed in a particular application and this, in some cases, could be as simple as reducing dust and spillage.”