stirred and allowed to cool to 50 u00b0 c before being cooled further to 25 u00b0 c using externally applied cooling water the ph had changed to 5 25 it was brought back to 6 90 with 0 7 grams of 18 sodium hydroxide the suspension was then allowed to settle overnight some of the clear supernatant was withdrawn and found to contain 2 ppm aluminum and 10 ppm fluoride the suspension was filtered and the filter cake was washed thoroughly with deionized water then dried in an oven two major greater than 35 wt crystalline phases were present al oh 1 76 f 1 24 monohydrate and 34 cryolite 34 inductively coupled plasma icp measurement found 11 38 and 11 25 wt sodium and 21 20 and 21 57 wt aluminum in duplicate analyses a slurry of 1450 grams of used aluminum chlorofluoride catalyst containing about 10 wt solids was added with stirring to 1450 milliliters of deionized water the acidic aqueous layer was separated and contained 4 86 wt fluoride and 0 88 wt chloride to 300 grams of 23 8 wt aqueous calcium chloride solution was added dropwise with stirring 500 grams of this acidic solution of the catalyst simultaneously 992 grams of 6 wt sodium hydroxide solution.