Mini-Encyclopedia of Papermaking Wet-End
Part Three: Equipment & Unit Operations
The function of a save-all is to remove fiber fines and other solids from white water. The clarified white water can then be used for showers, for stock dilution, and for make-down of certain types of chemical product. Also it can be stored with a much-reduced chance of materials becoming settled as deposits. Clarified white water from a save-all also may be discharged to wastewater treatment, minimizing the loss of solids from the process. The most widely used types of save-alls use disk screens or drum screens. Some long fiber or broke usually is added to aid in the filtration of fines. Dissolved-air-flotation (DAF) equipment is also used for flotation save-alls in many mills. Such processes are designed so that fiber fines and other solids rise to the top of a shallow chest where they can be skimmed off and recovered.
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