8/11/2019 slurry2of6.pdf

1/1

High density slurry: An engineering challenge

Technical overview 2 of 6

The second installment of our technical overview looks at thedesign considerations of our high density slurries and pasteapplications.

Energy and water conservation continues to be a crucialconsideration when designing or re-designing plants. AbelPumps are your solutions in high density slurry and pastetailings applications with significant cost savings.

Design Considerations:

Systems ApproachIncreasing solids concentration has a number of requirements that are different from conventionalslurry systems. Designing a high density system requires an overall systems approach as there isstrong dependence between the disposal site requirements, pumping requirements and preparationfacilities.A typical example that illustrates this is that high density systems are often considered, whenadditional storage capacity of a disposal site can be increased, due to the greater beaching anglesachieved with higher concentration slurry.

The beach slope achieved on a deposition site is a combination of many factors, such as depositionrate, terrain slope, particle size grading, layer thickness, drying cycle etc but one of the keyparameters is slurry yield stress (Sofra & Boger, 2001). Slurries with high yield stresses tend to

deposit at steeper angles than slurries with a low yield stress. It is necessary to establish the slurryproperties in terms of size grading, viscosity and yield stress that will result in the necessarybeaching slope to achieve storage capacity. Once this established, the process requirements toproduce the high density slurry must be investigated, together with the pumping requirements totransport the more viscous material. If the required storage capacity cannot be achieved without ahigh beaching angle, then alternative disposal site needs to be investigated. Close co-operation isneeded between different engineering disciplines to ensure the preparation facility can producesufficiently thick material that will form the required beaching angles after it has been transportedfrom the preparation site to the disposal facility.

Increasing solids concentration affects the following preparation and pumping processes:

Slurry preparation requirements to achieve consistently viscous material

Hydraulic design systems, which is more complex due to variable rheology

Mechanical design of the piping components due to higher operating pressures

Pump selection criteria between centrifugal and positive displacement pumps.

Reference: Paterson & Cook Consulting Engineers (Pty) Ltd.

ABEL pumps can handlehigh density slurries