Calcium chromate synthesis: process variables study [report]

B. Dillard
1978 unpublished
Gene ral Elec tric Comp any Neut ron Devi ces Depa rtme nt P. 0. Box 1150 8 Pot-»i-R bure . Flor ida 3373 3 Prep ared for the U. S. Depa rtme nt of Ener gy Albu quer que Oper atio ns Offi ce Unde r Cont ract No. EY-7 6-C-04-0 656 DISTR IBUTI ON QF THIS DOCU MENT IS UNLIM ITED DISCLAIMER ABSTRACT Five process variables affecting the synthesis of calcium chromate were studied. The variables were: molar ratios of reactants, substitution of anhydrous for aqueous ammonia, molal ity of chromic acid,
more » ... ate of addition of precipitating agent, and digestion times and temperatures. Results indicate that a product of higher purity and lower hydroxide ion concentration was obtained by use of a molar ratio of reactants of 2.1:1.1:1.0 (NH4OH:CrOs:CaO). Anhydrous ammonia could be substituted for aqueous ammonia if some engineering problems related to the synthesis process could be solved. The molality of the chromic acid had no effect on product purity over the range studied, but a significantly higher yield was obtained using chromic acid concentrations of 4.0 to 7.0 molal. A rate of lime addition from 0.3 to 1.5 liters per minute (4 to 17 minutes total addi tion time) produced a product of higher purity as compared to slower rates of addition. A digestion temperature of 80°C for 2 hours yielded a product of higher purity along with a high percent yield.
doi:10.2172/5070768 fatcat:l3qiseldk5drbhqrpagqscvjc4