Dissolution kinetics of ulexite in ammonium nitrate solutions

In this study the dissolution kinetics of the boron mineral ulexite, a sodium-calcium-borate hydrate (Na(2)O center dot 2CaO center dot 5B(2)O(3)center dot 16H(2)O), in ammonium nitrate solutions was investigated in a batch reactor. The effects of solution concentration, particle size, solid/liquid ratio. and reaction temperature on the dissolution rate were determined. It was found that the dissolution rate increased with increase in ammonium nitrate concentration and reaction temperature, and with decrease in particle size and solid/liquid ratio. No effect of stirring speed was observed on the conversion. It was determined that the dissolution rate fit to the chemical reaction control model. The activation energy of this dissolution process was found to be 58.2 kJ/mol. (C) 2008 Elsevier B.V. All rights reserved.