Water from HAR is run in a closed cycle. The solid material from the ash
cyclones and electric filters (ash mixed with fine fraction of dry shale in the
mass ratio of 99.8/0.2) is contacted with recycle water in wash-out facilities
of the plant, then collected in the sludge tank and directed to mixing with the
alkaline aqueous ash suspension from firing oil shale in the power station
boilers. The resulting suspension of solid waste material is directed to the
settling area of the ash ponds. In the inclined area of the latter the solid portion
of the suspension is settled, and the water is recycled to wash-out facilities.