Slurry tunnel boring machines circulate a bentonite suspension to support the face and transport spoil. Sustained progress depends on a separation plant that continuously removes excavated solids while conditioning and recovering the bentonite for reuse.
Specialised water treatment for TBM slurry, groundwater and construction runoff on underground projects.
Dissolved air flotation for oil, grease and fine-solids removal from equipment washdown water.
Screw and belt presses producing stackable cake from excavated spoil and treatment sludge.
This page walks through the slurry-shield TBM separation plant — screening, hydrocyclone desanding, desilting and centrifuge dewatering — and how each stage recovers bentonite for reuse. It is here because separation throughput, not the cutterhead, usually sets how fast a slurry TBM can advance. Each separation stage targets a progressively finer particle cut, dropping slurry density step by step until the bentonite is clean enough to recirculate to the cutterhead. Recovering the bentonite rather than disposing of it cuts make-up chemical demand sharply and reduces the volume of spoil that has to leave site, which is where most of the operating cost of a slurry drive is won or lost.
Excavated material ranges from coarse gravel to colloidal clay. The separation plant must handle the full grading at the instantaneous excavation rate, or the machine is forced to slow.
Face support depends on maintaining suspension density and yield stress within a narrow band. Excess fines raise viscosity and pumping cost; over-dilution loses support.
Bentonite is a significant consumable. Recovering and reconditioning it, rather than disposing of spent slurry, materially reduces project cost and spoil volumes.
Vibrating screens remove gravel and sand to roughly 100 micron, protecting downstream pumps and cyclones from abrasion.
Banks of desanding and desilting cyclones classify the suspension, cutting progressively finer particles while returning conditioned bentonite to the circuit.
Decanter centrifuges or filter presses dewater the fine fraction the cyclones cannot resolve, yielding a stackable cake and a clarified, reusable bentonite stream.
Modular screening and cyclone units sized to the excavation rate, with abrasion-resistant linings for tunnelling duty.
High-G decanters for fine-solids capture and bentonite clarification, with polymer conditioning to sharpen separation.
Buffer tanks, pumps and cake conveyors in a compact plot suited to constrained urban sites.
Reynolds & Bauhm designs and deploys treatment and recovery packages matched to your geology, programme and discharge consent.
Our expertise spans multiple industries with sector-specific water treatment solutions.