When a mud plant can't get barite to the weigh hopper, the problem is almost always in the dry-bulk chain: the powder won't leave the silo, the line is blocked or worn, or the airlock has stopped sealing. These faults stall weight-ups and wear out equipment. This page covers the common dry-bulk failures and what restores flow.
When the powder won't move
Barite and bentonite are cohesive powders — they pack, hold moisture and resist flowing. Left to gravity alone in a silo, they form a stable arch (a bridge) across the cone, or they flow only through a narrow central channel (a rat-hole) while the rest sits stale around it. Either way, discharge stalls and the operator sees a silo that reads full but won't feed.
Bridging and rat-holing
Bridging is beaten by keeping the powder fluidised: aeration pads or fluidising slides in the cone, a properly designed mass-flow cone angle, and, where needed, vibration or air blasters to break an arch. Moisture is a major aggravator — damp barite bridges far more readily — so dry conveying and instrument air and protection against moisture ingress are part of the cure, not an afterthought.
Line blockage and wear
In the conveying line, two opposite faults appear. Too low a velocity lets material drop out and block the line, especially at bends; too high a velocity blasts the line and bends with abrasive barite and wears them through. The dense-phase answer — low velocity, long-radius bends — sits between them, and a blocked line is cleared and then re-tuned rather than simply blown harder.
Airlock and pressure loss
The rotary airlock meters material into the line while holding back conveying pressure, and its rotor vanes run in an abrasive stream. As they wear, the airlock leaks air back up into the silo: conveying pressure and rate fall, and the plant slows even though the blower is working. Worn vanes are a routine wear item — replacing them on schedule prevents a slow, puzzling loss of conveying performance.
Key takeaways
Dry-bulk faults in a mud plant come from cohesive powder and abrasion: silos bridge or rat-hole when the cone isn't fluidised, conveying lines block at low velocity or wear out at high velocity, and rotary airlocks leak conveying pressure as their vanes wear. The cures are cone aeration and mass-flow design, dry air and moisture control, correctly tuned dense-phase conveying with long-radius bends, and scheduled airlock maintenance. Equipment details vary; the fluidise-meter-convey logic is constant.