By Colin Rice, Colin Rice Exploration and Training (Pty) Ltd

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Mechanical solids removal units, SRU's, are finding increasing application in mineral engineering projects because of the many advantages and cost savings that they provide. 

This is the seond article of Part 2 of our Technical Series on Drilling Fluids. Click here for an outline of the entire Drilling Fluids, Oils & Greases Series.

What is a solids removal unit?

An SRU is a mechanical device or devices that are used to remove solids from a water based drilling fluid. The devices that can be used vary in their effectiveness based on the size of the solid particles that they have to remove. Since diamond drilled cuttings are so small in size the only mechanical devices capable of efficiently removing solids are hydro-clones, SRU's are therefore cyclone based.  

Drilling fluid returned from the borehole is directed into a small return sump and is then pumped to the SRU where it is directed into a horizontal centrifuge at high pressure. The solids are spun out of the centrifuge and the "cleaned' drilling fluid is returned to a suction tank from which it is recirculated through the borehole. Because the centrifuge is so effective, it is possible to drill a borehole with incredibly small circulating volumes. Not only does this reduce the amount of water required to drill a borehole, it also reduces the consumption of fluid additives.

For a detailed explanation of the benefits of an SRU, read this article.

Other articles in Part 2 OF the Drilling Fluids Series.