Control system minimises dust escape during grab discharge

7th July 2017 By: Simone Liedtke - Writer

Control system minimises dust escape during grab discharge

DUST CONTROL The grab discharge cycle includes transferring materials down the line using handling systems

Materials handling equipment supplier BLT South Africa’s (SA’s) Samson travelling Eco-Hoppers have an effective dust control system that minimises the escape of dust during the grab discharge cycle.

“Environmental pollution, which is caused by fugitive dust, is a major problem in dry bulk handling,” states BLT SA MD Ken Mouritzen.

Therefore, Eco-Hoppers are designed to suit the characteristics and flow properties of virtually any bulk material, including coal, iron-ore, gypsum, copper concentrates, soda ash and wood chips, he explains.

“These robust grab unloading hoppers, which are manufactured in China to withstand tough conditions in bulk handling, offer handling rates of up to 5 000 t/h, depending on grab crane performance. Handling rates depend on the speed of handling the feed material,” he points out.

He adds that the low maintenance system also reduces investment and operating costs, owing to fewer moving components and a lower capital outlay.

Eco-Hoppers have an upper and lower section, separated by a dust retention feature called the Flex-Flap. This divider – which comprises a series of pressed steel sections and vertical rubber flaps – opens to allow for the free flow of material into the hopper and closes to prevent the flow of air out of the hopper.

When bulk material is released by the grab, it falls through the Flex-Flap and accumulates in the inner hopper below. The hopper system then automatically closes as a result of the newly created pressure differential between the hopper and the atmosphere, forming a seal to contain the dust-contaminated air, Mouritzen explains.

“Integral reverse jet filters are positioned around the hopper inlet to extract and clean the dust-laden air. Collected dust is then recycled into the mainstream of material,” he adds.

The Flex-Flap feature also reduces the volume of exhausted air, which is necessary to control fugitive dust, and requires the use of small, compact filters rather than a large dedusting system.

The standard Samson travelling Eco-Hopper series includes circular hoppers, which are designed to accommodate grab capacities of between 1 m3 and 37 m3.

“Each hopper size has a corresponding high or low-level framework, depending on the chosen discharge option.”

Material from the Eco-Hopper can be discharged directly onto a belt conveyor for a fixed installation. In this case, the bulk material is reclaimed by a gravity discharge unit, which feeds the material onto the conveyor at the required output rate. Using a dust-controlled loading spout, the hopper can discharge directly into tipping trucks.

Samson travelling Eco-Hoppers can be rail-mounted or bolted to suitable concrete foundations. “For applications requiring a higher level of manoeuvrability, hoppers can be supported on solid rubber-filled pneumatic tyres. The combination of fixed and steering axles provides the option of power travel.”

Custom-designed hopper solutions that suit specific application requirements are also available.

The Samson travelling Eco-Hoppers’ range of bulk handling equipment also includes link conveyors, other grab hoppers, surface feeders, radial boom stackers and mobile ship loaders.