Continuous washer for non-filterable hydroxide precipitates - having initial mixing zone with subsequent horizontal settling zone

摘要

Pptes. which are difficult to filter are washed in continuous process with final sepn. of suspension and wash liquor. The suspension is the heavy phase and the wash liquor the light phase, both being intensively mixed. The agitated mixture is then fed along a horizontal settling zone to allow sedimentation. By means of the flow and of gravity the heavier phase collects and is subjected to a horizontal motion. The two phases are sepd. at the end of this horizontal zone. The sepd. heavy phase can then be recontacted with more of the lighter phase in a series of contactors arranged in series giving repeated mixing and sedimentation processes. For use in washing gelatinous pptes. of metal hydroxides esp. Ni(OH)2 and Cd(OH)2. Gives a process for washing any such aq. suspensions in a quasi counter current wash which is economical in water usage and low in energy usage. Such materials cannot be washed on filters because they rapidly clog them.