Design and operating principles can be found in suppliers literature. Mud cleaners consist of a desilter mounted over a fine mesh screen of 150‑240 mesh. The desilter underflow is treated mechanically by the fine 150-240 mesh screen which allows the liquid phase and any barites present to pass back into the circulating tank while the drilled solids above 75 microns (for 200 mesh screen) are removed.
It is clear from this statement that any drilled solids of particle size less than 75 microns will also be returned to the mud. Return of drilled solids to the mud is the main disadvantage of mud cleaners. In addition, mud cleaners are known to disintegrate drilled solids into very fine particles which are more difficult to remove.
- Mud cleaners shall be used as a substitute for desilters in the following circumstances:
- With weighted muds.
- With mud systems having an expensive or environmentally damaging liquid phase, such as oil based mud.
Note: Caution must be exercised in the use of mud cleaners for such applications since whole mud losses can be rather high.
- Mud cleaner shakers shall be switched on together with feed pumps.
- The operational guidelines outlined for desilters shall also be applied to mud cleaner cones.
- Mud cleaner screens shall be inspected regularly and changed immediately if they are found to be defective.
- Feed pumps shall be switched off prior to stopping the mud cleaner shakers to minimise whole mud losses.
Notes: Mud cleaners must not be used in situations where desilters may be applied since the mud properties may be adversely affected by the inevitable introduction of fines and consequent change in particle size distribution of the mud. It is not recommended to run the mud cleaners all the time.
If primary shakers are fitted with 120 mesh screens, or finer, mud cleaners are rendered ineffective.