Weba Chute Systems has installed more than 300 transfer points at various sections of Assmang’s Khumani Iron Ore Mine in the Northern Cape and the most recent 19 chutes are poised for hot commissioning as part of the Whims Expansion Project by the end of February 2013.

Assmang, which is jointly owned and controlled by African Rainbow Minerals and mining holding company Assore, initiated the KEP to increase the Khumani mine’s capacity from 10 Mtpa to 16 Mtpa. Of the 6 Mtpa expansion, 4 Mtpa is intended for the export market and 2 Mtpa for the domestic market.

The Weba Chute Systems order forms part of the greater Khumani Wet High Intensity Magnetic Separation (WHIMS) Project (KWP) that will incorporate a new WHIMS super fines beneficiation circuit and related infrastructure into the existing Parsons processing plant.

The Weba Chute team was tasked with engineering chutes capable of reducing production losses related to blockages, eliminating spillage and achieving an 80% maintenance-free transfer point.

"The major application requirement on the latest Expansion Project (Whims) was to cater for the extreme stickiness of the material, which is prone to choking and blocking in transfer points," Weba Chute Systems’ managing director, Mark Baller, says. "Although we have extensive experience with the type of material being handled at this operation, the application in itself presented certain challenges owing to the super fines being transferred from conveyor to conveyor.

"These particle sizes range downwards from 2mm to micron proportions and the material is very abrasive and sticky. Our design has, therefore, incorporated 20mm high alumina ceramic engineered tiles to facilitate the necessary level of abrasion resistance and the free flow of the sticky material."

Baller adds that one of the primary objectives during the design phase was to ensure that the angle of flow within the chute was such that it would not choke or block during material transfer.

In total, 19 chutes were custom designed, each ceramic lined and taking specific installation and application factors into account. The tonnage throughput rate varies from 120tph to 900tph, feeding onto the receiving conveyor. Conveyor widths vary from 750mm to 900mm, with belt speeds between 2.24m/s and 1.85m/s.

Four of the chutes supplied by Weba Chute Systems have been engineered to accommodate a Multotec cross belt sampler.

The company is now in the design phase for additional chutes for the Khumani Optimisation Project (KOP), with installation scheduled to start in February 2013 as part of an interface with the WHIMS project.

Lined transfer points and chute systems

Lined transfer points and chute systems designed and manufactured by Weba Chute Systems are proving successful in a number of applications, both locally and internationally.

"This is generally a material-specific application, where the characteristics of the material being conveyed means that the internal angle of friction results in a bonding effect that will inhibit material flow or result in blockages," explains Baller. "In these instances a lining material is selected to reduce the amount of friction and facilitate the flow of the material through the chute. By harnessing Weba Chute System principles, we’ve been able to achieve excellent control of the material being conveyed and virtually eliminate blockages, even with the stickiest of materials."

Belt loading is another area known to create problems in the movement of sticky material and Baller says it is essential that the outlet configuration is engineered to achieve optimum belt loading and minimal impact.

Each Weba Lined Chute System is custom designed for the specific application, taking into account factors such as belt width, belt speed, material sizes, shape and throughput. Easy access has been provided for inspection and maintenance purposes. A major advantage of Weba chutes is that they do not require ongoing supervision — translating into genuine savings in manpower and related costs.

Extensive experience and technical expertise, coupled with applications knowledge and system design carried with sophisticated 3D computer software, have positioned Weba Chute Systems as the leader in its field.

"All data received from our customers is fully verified and, in many instances, our highly skilled personnel are able to make cost saving recommendations," he says.