Weba Chute Systems began replacing ageing competitor chutes for a South African steel producer recently, with the customer impressed by the immediate reduction in spillage, dust, and noise. The installation of over 30 engineered transfer chutes is translating into improved chute performance and a working environment that requires much less regular cleaning.
According to Dewald Tintinger, technical manager and designer at Germiston-based Weba Chute Systems, the upgrade at the steel plant brings multiple benefits to the operation. These include a cleaner and safer working environment, with significantly less expenditure on cleaning spillage.
Controlled material flow, something which the company is known for, also means that sinter degradation is minimised, for optimal furnace performance.
“We are replacing 16 chutes in one sinter plant, and 17 in another,” says Tintinger. “The installation process has begun and will continue through to the end of this year.”
The cooling circuit in each plant receives sinter after it has been reduced to a minus 200mm lump size, and passes over a circular cooler. An interesting feature of the circular cooler discharge chute is that it is mounted on load cells. This ensures a certain mass of material is maintained in the chute, which operates under choke conditions to reduce wear and tear on the vibrating feeder below.
“The top half of this chute is a fixed unit, while the bottom half rests on the load cells which measure the material in the chute and regulate material feed,” he explains.
As it makes its way to the furnace, the customised design of the Weba chutes control the speed of the material flow. The strategic use of dead boxes inside the chute also facilitates a lining of sinter, with material moving on material reducing wear on the metal structure.
“The way our chutes control the flow of material holds special benefits for sinter plants,” he explains. “To allow the furnace to operate efficiently, it is important that fines are kept to a minimum. By limiting the velocity and impact pressure of the material, our chutes reduce the degradation of sinter lumps into fines.”
Tintinger highlights that the company investigated a range of factors when planning for this retrofit, to enhance the overall performance of the circuit. Its three-dimensional laser equipment made for quick and accurate assessment of the site layout and equipment dimensions. Certain adjustments of the chutes’ general arrangement were also proposed and implemented.
“Our well-proven modus operandi is to survey existing arrangements with 3D scanning equipment to eliminate the chance of human error, and this is particularly advantageous where the site is very dusty or difficult to navigate,” he says. “Our resulting model is therefore very accurate, and we can identify any issues in the transfer point arrangement.”
Certain fine-tuning of layout arrangements in this project prioritised the central loading of material onto belts and screens. This, in turn, assisted in solving issues where belts were being pushed out of alignment, for instance. Attention to this level of detail allows the company to provide a performance guarantee with its new chutes.
“The customer was particularly struck by how quiet our chutes are, which is a result of the controlled flow and the protective lining the material moving on material creates,” he says. “Although there are dust extraction systems in place, the plants are also enjoying less dust creation as there is reduced impact.”