A large proportion of aggregate used in the production of concrete and road wearing materials require to be washed in order to maintain a consistent end product free from impurities.  In both instances the cleaner the aggregates and sand the less cement and bitumen is required in the mix.  The cement and bitumen represents the majority of the mix cost although representing only a fraction by weight.  It is therefore of the utmost importance to maintain a high quality clean aggregate.
  
To initiate the washing of aggregate the material is passed over a Finlay vibrating screen fitted with water spray jets.  This both washes the stone products and separates the sand from the stone.  In most situations it is also normal to split the stone products into finished grades at this stage.
 
Where aggregates are heavily contaminated by clays a rotating scrubber barrel or Logwasher can be incorporated into the system to ensure adequate cleaning.  The sand product flows with the wash water to a Hydrasander where the silt and clay are removed and the sand dewaterered.  The silt-laden wastewater from the Hydrasander is normally gravity fed to either settling ponds or a water cleaning system such as the Finlay Siltmaster.
 
In quarry situations it has now become economically feasible to wash the material previously thought of as waste from the grizzly at the primary jaw crusher.  Using the Finlay screens, Scrubber Barrels and Siltmaster it is now possible to retrieve the valuable stone product.  The Siltmaster enables this to be done without the need for settling ponds for the wastewater.

100TPH Mobile Sand washing plant incorporating Finlay 310 Hydrascreen, Finlay 120E Hydrasander and Finlay 524 Stockpilers

Crusher grizzly waste washing plant incorporating scrubber barrel, washing screen and Siltmaster water cleaning system.

©  June 2001, M.H. Screening