This paper describes a simple means to settle fine particulate uranium diox
ide in the grinding sludge water obtained during the centreless grinding op
eration of cylindrical-sintered uranium dioxide pellets to bring down the l
evel of uranium in the supernatant to well below the permissible limits. Th
e present method offers feasibility of utilizing the supernatant, thereby a
voiding the necessity of long term storage of the sludge water. Additionall
y, it offers a way of recovering significant quantities of precious uranium
dioxide that is in the form of suspended particulate material in the grind
ing sludge. In the absence of any treatment, the as-received grinding sludg
e, even after very long settling times, contains a considerable quantity of
uranium in the supernatant in the form of very fine particulate material.
Uranium being radioactive and keeping the radiological problems in view, th
e decant solution needs to be stored. The strategy described here brings do
wn the uranium level in the decant solution to much below the permissible l
evel by settling in considerably short duration with potash alum (potassium
aluminium sulphate) additive. The process of settling is studied in the li
ght of the electrical nature of the sludge particles, dosage of alum and pH
, among others. (C) 2000 Elsevier Science S.A. All rights reserved.