A mud cleaner looks like a desilter with a shaker bolted underneath, and that is exactly what it is — a bank of small hydrocyclones mounted over a fine vibrating screen. It exists for one job that a plain desilter cannot do: recover expensive barite on weighted mud instead of dumping it. Knowing when to reach for it comes down to what your mud weighs.
What a mud cleaner actually is
Strip a mud cleaner down and the top is identical to a desilter: a bank of 4-inch cyclones making a fine cut, around 15 microns and up. The difference is underneath. A desilter sends whatever the cones throw out the apex straight to the discard; a mud cleaner lands that apex underflow on a fine-mesh screen — typically 150 to 200 mesh, about 74 to 105 microns — instead. That single screen changes everything, because it gets a second chance to sort what the cones concentrated.
On that screen, the liquid and the fine, dense barite pass through and return to the active system, while the larger, lower-density drilled solids are retained and discarded as waste. The high-frequency vibration dewaters the retained solids so you are not throwing away mud with them. In one compact skid you get two-stage separation — centrifugal in the cones, then vibratory on the screen — which is why it slots neatly between the primary shaker and the centrifuge, handling the 15-to-74-micron range that escapes the shaker — the band Rig IQ helps you place the right stage against.
Why weighted mud is the whole reason it exists
The problem a mud cleaner solves is a density problem disguised as a size problem. A hydrocyclone sorts by mass, not by what the particle is, so it preferentially removes the densest material in the feed. On weighted mud that densest material is barite — specific gravity around 4.2, against drilled solids at about 2.6 — and much of it is fine. Run a bare desilter on weighted mud and the cones send that expensive barite straight out the apex to waste. As the field rule puts it: never run bare desilters on weighted mud — you are not cleaning the fluid, you are paying to dump barite.
The mud cleaner closes exactly that gap. Because barite is ground mostly below 74 microns, it passes the fine screen and goes home to the mud, while the coarser drilled solids stay on the screen and leave. The economics kick in around 10.5 ppg (about 1.26 SG): above that weight, the value of the barite in the underflow makes recovery worth the equipment. Whether the barite you would save actually justifies the unit at your mud weight and circulation rate is the kind of trade Rig IQ is built to work out before you rig anything up.
When a fine-screen shaker beats it — and unweighted mud
The mud cleaner is not automatically the answer, and honest sizing means admitting where it loses. It was designed in an era when shakers could only run about 100-mesh (149-micron) screens, too coarse to hold barite. Modern linear-motion shakers run fine screens down to 200 mesh, and many experts now prefer a good number of fine-screen shakers to a mud cleaner where space allows: the shaker screen has longer life, processes the full circulation rate, and reports lower barite losses. A mud cleaner does not treat the whole circulation rate, has a small screening area and high underflow viscosity — which is why barite losses over a cleaner screen can exceed those over a shaker screen of the same mesh.
On unweighted mud the calculus flips entirely: there is no barite to protect, so you simply run the unit as a plain desilter and skip the screen — screening the underflow is unnecessary unless you are pulling abrasive solids ahead of a centrifuge. So the decision is genuinely conditional: weighted mud above the threshold with limited fine-screen shaker capacity is where the mud cleaner earns its place; elsewhere, fine-screen shakers or a barite-recovery centrifuge often serve better. Running the numbers on both paths in Rig IQ keeps that an engineering decision rather than a habit.
The rule
Mud cleaner = desilter cones (4") over a fine screen (150–200 mesh / 74–105µm).
Weighted mud (> ~10.5 ppg): use it — the screen returns fine barite (SG 4.2) and discards drilled solids (SG 2.6). Never run a bare desilter here.
Unweighted mud: run it as a plain desilter (screen not needed).
Modern caveat: fine-screen (200-mesh) shakers often beat a mud cleaner — longer screen life, full circulation rate, lower barite loss.
Read the decision off the mud weight. A hydrocyclone sorts by mass, so on weighted mud a bare desilter dumps barite (SG 4.2) — and above ~10.5 ppg that is expensive. A mud cleaner’s fine screen returns the barite and discards drilled solids. On unweighted mud, run it as a plain desilter. And be honest that modern fine-screen shakers often beat it — size both before you commit.
Common questions
What is a mud cleaner used for?
Recovering barite on weighted drilling mud. It is a bank of desilter cyclones over a fine screen (150–200 mesh): the cones concentrate solids, and the screen returns fine barite and liquid to the mud while discarding the coarser drilled solids — something a plain desilter, which would dump the barite, cannot do.
When should you use a mud cleaner instead of a desilter?
On weighted mud, roughly above 10.5 ppg, where a bare desilter would throw expensive barite away. On unweighted mud there is no barite to protect, so you run the unit as a plain desilter and the screen is unnecessary. Where the rig has fine-screen (200-mesh) shaker capacity, those shakers often outperform a mud cleaner.
Why does a desilter lose barite on weighted mud?
Because a hydrocyclone separates by mass, not by material. Barite (specific gravity ~4.2) is much denser than drilled solids (~2.6), so the cones preferentially send barite out the apex underflow — straight to waste on a bare desilter. A mud cleaner's fine screen recovers that barite before it is lost.
