Live-Bottom Silos and Bunkers

SPIRAC has been the market‑leading supplier of live‑bottom silos and bunkers for the wastewater industry since the 1980s. Hundreds of installations are operating worldwide—many with decades of continuous service. This long operational history reflects the reliability, durability, and engineering quality that SPIRAC systems are known for.

SPIRAC’s live‑bottom silos and hopper systems are purpose‑designed for the storage, transfer, and controlled discharge of non–free‑flowing materials, particularly dewatered sludges. These materials are often sticky, cohesive, or high in moisture, and can easily cause bridging, ratholing, and blockages in conventional silo systems. SPIRAC’s designs eliminate these issues by ensuring consistent, reliable flow under all operating conditions.

While the overall design is based on standard engineering principles, every silo can be customized in size, geometry, and orientation to meet specific project and site requirements. Three standard configurations offer a wide range of cost‑effective layout options.

SPIRAC silos are typically top‑loaded via shaftless spiral incline conveyors and/or vertical/horizontal spiral systems. Discharge is managed by large‑diameter, large‑pitch shaftless (screw) spiral conveyors operating at low RPM. This combination provides a true live‑bottom effect that delivers continuous, uniform material movement across the entire silo floor—preventing flow bottlenecks even with highly cohesive materials.

Rectangular geometry is preferred to maximize conveyor coverage and efficiency. A tapered floor supports the live‑bottom mechanism; while it reduces total storage capacity, it greatly enhances flow performance, making these silos ideal for small to medium volumes where consistent and dependable discharge is more important than maximum capacity.

Live‑bottom silos offer excellent bridging control, low energy consumption, and minimal maintenance requirements due to their slow‑speed, high‑torque operation and lack of hydraulic components. They represent a cost‑effective solution for facilities handling challenging sludge materials that demand reliable flow assurance.

Typical handled materials include wastewater/'industrial sludges, and other difficult, non–free‑flowing solids that are prone to ratholing.