A pneumatic conveying system transports bulk materials such as meal, fines, pellets or dust through enclosed pipework using a stream of moving air, rather than mechanical conveyors like belts or screws. Material is either pushed through the pipe under positive pressure from a blower, or pulled through under vacuum (negative pressure) generated by a fan or exhauster downstream.

These systems are common in feed mills wherever a fully enclosed, low-maintenance transfer path is needed — particularly for moving dust from cyclones and bag filters back into the production line, or for transferring fine ingredients and additives between storage and processing without the housekeeping issues that open conveyors can create.

Pneumatic systems are generally divided into dilute-phase (high air velocity, low material concentration, suited to lighter or more fragile materials) and dense-phase (lower velocity, higher material concentration, gentler on the product but requiring more sophisticated control). Dilute-phase systems are by far the more common configuration in feed mills, owing to their simpler equipment requirements and lower capital cost, while dense-phase systems tend to appear where minimizing product degradation or dust generation during conveying is a higher priority than energy efficiency.

System design requires careful attention to pipe routing, since bends, elbows and vertical-to-horizontal transitions all introduce pressure losses and wear points; abrupt direction changes are a common source of both increased energy consumption and accelerated pipe wear from material impact, which is why long-radius bends are generally preferred over sharp elbows wherever layout allows.

Rotary airlocks, typically installed at material entry and exit points, are essential components of most pneumatic systems, since they allow material to be introduced into or removed from the pressurized or vacuum airstream without allowing excessive air to escape or be drawn in, which would reduce conveying efficiency and could affect dust collection performance elsewhere in the system.

Energy consumption per tonne moved is typically higher than mechanical conveying, which is the main trade-off against pneumatic systems' cleanliness and flexibility of routing — a pneumatic line can be routed around obstacles in ways that would be impractical for a rigid mechanical conveyor, making pneumatic conveying particularly attractive in retrofit situations or congested plant layouts where running a new belt or screw conveyor route is not feasible.