Novel instrumentation has been developed to detect stationary bed conditions for settling slurries by using externally-mounted sensor heads with a heater and a temperature sensor. These heads are configured in such a way that suitable data are obtained online. Additional sensor heads can be mounted along the circumference of the pipe to detect the actual height of the stationary bed, at pre-determined levels.

The embedded software in the Settled Bed Detector (SBD) provides unambiguous outputs for full flow, stationary bed, or bed heights at predefined levels, i.e. 5%, 10% or 15% of the internal pipe diameter. The knowledge about the existence and the vertical extent of the stationary bed and its longevity can reduce the risk of pipeline blockages as part of an optimised mineral process control strategy.


During recent mine trials with the SBD, it was discovered that contrary to the expectations regarding the performance of traditionally designed slurry pipeline systems, stationary beds or even sliding dunes did occur quite frequently within a few hours. Fortunately, the pump characteristics were able to increase the flow rate and thus removed the temporarily formed stationary beds. The new instrumentation provides the opportunity to detect stationary beds and to correlate their existence with other process parameters, like volumetric flow rate, slurry density, and preferable even with the prevalent particle size distribution.

The concept of using thermal sensors, sometimes in direct contact with slurry flow, to detect flow behaviours, their transitions and anomalies during pipe flow has been published as early as 1979 (1,2,3). Results of two thermal probes protruding through the pipewall to be in direct contact with the slurry flow or with the developing stationary bed to detect the bed height were presented in 2005 (4). However, a serious limitation of protruding probes was the generally convex shape of theses probes, which created undesired turbulences at their interface with the concave surface of the inner pipe wall.

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