FLSmidth's Dorr-Oliver® rake classifier is a rectangular classifier tank with an inclined channel, and equipped with a reciprocating raking mechanism which transports the settled solids towards the upper discharge end. Solids are dewatered and, if necessary, washed by addition of wash liquid.

How does it work if two Classifers are installed (Deliquoring and Wash Classifier)?

The deliquoring Rake Classifier provides a feed distribution tank on top of the Rake Classifier ensuring distribution into the trough classifer. The liquor then overflows into an overflow collecting launderer which is connected to the discharge piping system. The settled sand is then deliquorted partly while it is raked out of the trough and oasses the deliquoring zone of the classifer.

The deliquored sand falls by gravity into the trough of the first Wash Classifer where it is mixed with the overflow liquor of the second Wash Classifier. The overflow of the first Wash Classifer is then collected in the overflow collecting launderer connected to the discharge piping system. The settled sand is deliquored partly while it is raked out of the trough and passes the deliquoring zone of the first Wash Classifier. The deliquored sand then falls by gravity into the trough of the second Wash Classifer where it is mixed with wash water. The liquor of the second Wash Classifer overflows by gravity into the trough of the first Wash Classifer via two launderers between both Wash Classifiers. The settled sand is deliquored partly while it is raked out of the classifers' trough and passes the deliquoring zone of the second Wash Classifer. Wash water is fed to the sand of the second Wash Classifer via spray nozzles installed within the deliquoring zone. After further deliquoring, the washed sand is discharge passing the discharge chute installed at the end of the deliquoring deck.

The above described system is designed for solids flow rate of max. 37 t/h within 124.9 m³/h slurry.