Wednesday 20th Nov, 2019

Bulknet builds bespoke screw solution

When a major miner needed to move a heavy and hazardous material, Bulknet was the only company able to meet its strict requirements.

When a major miner needed to move a heavy and hazardous material, Bulknet was the only company able to meet its strict requirements.

As part of a major multinational mining company’s new project, bulk material handling specialist Bulknet was selected to design and manufacture a unique screw feeder.

Positioned under a 150-tonne storage hopper, the screw feeder supplies nickel sulphate crystals to a bagging system below. The system needed to start under a full load from the hopper through a four-metre-long outlet. This would allow the client to fill and store material in the hopper for when planned maintenance was undertaken upstream.

The hopper’s significant capacity and the weight of the material would place the screw feeder under extreme pressures. Special consideration was necessary in the design phase to ensure it was robust enough to handle the task.

When the screw rotates, it creates shearing force and under a full load, immense pressure is placed on the spiral gear drive unit. A Bonfiglioli planetary drive was selected to handle this as it was ideal for low speed, high torque and small footprint tasks such as this.

Related stories:

“Deflection of the centre tube was a major concern during the design and consultation phase,” Geoff Thomson, Business Development Manager for Bulknet, says.

“If there is too much deflection on a screw conveyor’s centre tube, unnecessary radial loads are transferred to the drive and tail bearings, resulting in faster wear.

“In addition, extra stresses are exerted on the centre tube’s welds, reducing its fatigue life.”

Nickel sulphate crystals are a class one carcinogen, which presents a hazard to human health. As such, the screw feeder had to be completely air-tight, so Bulknet incorporated a number of sealed gaskets and air purged Clamp Ezy Seals to ensure no leakage of the product. Bulknet then manufactured the feeder using Grade 316 stainless steel and delivered it to the client.

As a specialised designer and manufacturer of screw conveyors, Bulknet was also able to offer the customer engineering expertise and spare parts to keep the system running after installation.

According to the customer’s feedback, Bulknet was the only screw feeder manufacturer able to meet all of the unique design requirements needed for its screw feeder.