Tunneling

To transport solids from tunnel boring and to stabilize the working face, bentonite is added to the conveyance medium of water as required. The model SKC 30-K mixer is used to manufacture this bentonite suspension. This mixer generates an optimal, colloidally dispersed slurry that is immediately ready for use, as subsequent swelling through colloidal mixing is no longer required.

As drilling progresses, the solid is continuously extracted from the mud pump in the tunnel drilling rig and pumped to the desanding plant (BE 300-C or BE 500 depending on the volume required and tunnel cross-section). The desanding plant continuously separates the solids up to a certain grain size (60 µm to 20 µm, depending on the version) out of the slurry, allowing for the cleaned slurry to be pumped directly back to the tunnel drilling rig within the closed circuit.

For soil fractions smaller than 20 µm, it is possible to clean these down to 10 µm using the BD 90 decanter, or to separate all solids from the fluid by adding flocculating agents.

The slurry tanks under the separation systems of model ST are outfitted with agitators so that the slurry or solid particles inside the slurry are either kept in motion or fed to a pump organ, depending on the application. Horizontal or vertical agitators are available for this purpose.