To provide technical staff with the opportunity to view the inside workings and dynamics of a slurry pumping system, pumps manufacturer KSB Pumps & Valves has produced and showcased a fully transparent operational slurry pump loop model.

The working model that was showcased at the 2014 Electra Mining Africa trade show, in September last year, depicts a typical mill cyclone feed application. It has a clear casing pump, cyclone and pipes to enhance this visualisation and uses different sized and coloured glass beads to represent solids.

KSB slurry pumps product manager Mohamed Trabelsi says the slurry loop model was built as a training aid to give engineers a chance to study various parameters, such as pipe diameters, inclines, declines, flow rates and their effect on sediments and on a slurry pump system.

“KSB has done a significant amount of research and development on slurry pumping worldwide and we wanted to show our customers how the system works, as well as the do’s and don’ts of designing a slurry system,” Trabelsi says.
He emphasises that the system also showcases the expertise of KSB in terms of design, research and development, as well as its system integration expertise on any level.

Trabelsi explains that the model begins with a clear casing pump, driven by a variable speed drive (VSD), which allows speed to vary from 150 rpm to 2 000 rpm. The system then splits into two sections with different pipe diameters to show the effect of different velocities on slurry transport.

The slurry is then transported into two sections where it flows into a 45 °C section, followed by a vertical loop, which shows what happens to slurry in different inclines.

“To do this it uses different size particles of the same specific gravity with different colours to indicate the effect on settling velocities,” he says.

“The flow then goes into the cyclone where one can see the underflow and the overflow. For purposes of the demonstration, the underflow and overflow go back into the sump; however, in a typical processing application the fine material would proceed to the next processing step, while the underflow, such as larger solids would go back to the mill for further grinding,” he adds.

Pipe Dynamics
KSB Pumps & Valves US product manager Richard Inglett notes that the model is designed to answer technical dilemmas that designers and engineers are faced with on a daily basis.

“For example, when viewing the two pipes (2" and 1 1/2" diameter) at full speed, you can see settling slurries on the 2" pipe, owing to the larger diameter and reduced flow. On different inclines it also shows that, on the 45 °C pipe you can see unsteady bed developments, which represent the worst case for the transport of settling slurries,” he highlights.

Inglett further notes that, for long distance pipelines it shows that the degree of incline must be taken into account for the system calculations.

Since inclined sections can cause instability and plugging – even in short sections – it indicates that, when possible, horizontal or vertical sections are more preferable than gradual inclines or declines, he says.

Meanwhile, the aim of the VSD is to show what happens to materials at different pump speeds and where it reaches its best efficiency point (BEP).

“At this point there is minimal recirculation of fluids inside the pump. Away from BEP, the system shows how recirculating slurry within the pump – that is not discharged – becomes entrapped. These slurries are then driven between the impeller and the suction liner and can lead to premature pump wear and a shortened operational life span,” says Inglett.

This system also highlights the importance of proper pumps selection and shows users how slurries behave throughout the pumping system, Trabelsi says.

In light of this, the company offers a new LCV series of vertical slurry pumps, which can withstand harsh mining operational environments.

“The pumps allow for interchangeable wet-end components with the common LCC range of horizontal slurry pumps for routine maintenance requirements,” Mining Weekly reported in June last year.

These pumps vary in discharge sizes – from 50 mm to 300 mm – and feature a flow rate of up to 1 360 m3/h. The pumps can operate to a head of up to 38 m. Shaft sizes are available from 90 m to 200 mm, while cantilevers range in size from 900 mm to 2 100 mm.