Fluorine-contg. waste water processing - by mixing with calcium nitrate tetra:hydrate and adding carbon di:oxide and ammonia (NL 5.8.80)

摘要

The removal of F cpd. -contg. waste waters, formed by scrubbing waste gases from a fertiliser plant in which crude phosphate is solubilised with HNO3 and Ca(NO3)2.4H2O is partly or completely pptd. by cooling and sepd., is effected by (a) mixing the waste waters with the Ca(NO3)2.4H2O sepd. and (b) converting to CaF2. CaCO3 and an NH4 NO3 soln. by the addn. of CO2 and NH3. The F cpds. are bonded to Ca ions and the water is used up in NH4NO3 soln. Waste water removal requires no additional appts.