Solubility of Amorphous Sodium Aluminosilicate and Zeolite A Crystals in Caustic and Nitrate/Nitrite-Rich Caustic Aluminate Liquors

摘要

The solubility of amorphous sodium aluminosilicate solid and zeolite A crystals in sodium hydroxide and nitrateditrited sodium aluminate solutions has been determined at temperatures of(303.15,338.15,and 403.15)K and as a function of solution NaOH,NaNO_3j NaNO_2,and Al(III)concentrations.Similar solubilities were measured when equilibrium was approached from below(via dissolution in undersatu-rated liquor)and above(by precipitation from supersaturated liquors).The solubility(expressed in terms of SiO_2 and Al(III)concentrations)increased monotonically with increasing temperature,solution ionic strength,and hydroxide concentration for both amorphous and zeolite A phases.However,the solubility decreased with increasing solution Al(III),NO_3~-,and NO_2~-concentrations and was significantly higher for the amorphous than the zeolite phase at all temperatures and solution conditions.