Dry flocculent agent removes fines from concrete plant settling basins

Ready mixed concrete plants are recycling process water to attain more sustainable operation and save on discharge costs or the amount of fresh water consumed. As cement fines accumulate in settling vessels, process water becomes less usable in fresh concrete mixes due to limits on the amount of solids that can be present in the makeup water. The solids also present scaling problems in pumps, valves and other fittings in the piping systems that carry recycled water.

Ready mixed producers have attempted to use various filters, polymers and flocculents to settle out the cement fines to clear the water with mixed results. Most of these products need to have process water pH at a specific point in order to work effectively, coupled with some form of mixer to stir the polymers into the process water. The polymers must be premixed and dosed with a liquid polymer feeder. Fresh stock solutions must be made up on a regular basis.

Fortrans Inc. and a manufacturing partner have introduced a new non-pH-specific dry flocculent called Drum-Floc, which is broadcast over the surface of the process water settling basin, then mixed in with a bucket loader. Drum-Floc can be mixed in a closed basin by mixing with an air sparger line or circulation pump, followed by pump or vacuum removal of solids. Once the product is added to the process water, all the solids will settle out in about 30 to 45 minutes. Once the solids have been settled, they will not remix into the clear water even if agitated or stirred. Operators can simply pump off the clear water and remove the settled solids with a loader.

If a producer is operating a concrete reclaimer, Drum-Floc can be added to the process and all of the solids will settle out when the slurry is discharged into the basin. In many reclaimers, there is an added benefit: the sand coming out of the reclaimer will be cleaner and in some cases may be used in lieu of virgin sand.

A non-hazardous material, Drum-Floc remains in settled cement fines, not in the recycled water, where it could hamper reuse in fresh concrete. The clear water may be pH adjusted and discharged to the environment if necessary. — 866/958-7267; www.fortransinc.com