A SEMIEMPIRICAL KINETIC-MODEL FOR DISSOLUTION OF COLEMANITE IN AQUEOUS CH3COOH SOLUTIONS

In this study the dissolution of Colemanite in aqueous acetic acid sol utions was investigated in a batch reactor employing the parameters of particle size, solid-to-liquid ratio, and temperature. It was found t hat the dissolution rate increases with increasing temperature and dec reasing solid-to-liquid ratio and particle size. The most effective pa rameter was particle size with a power of -1.420 after temperature and solid-to-liquid had less effect than the other parameters. The conver sion rate increased up to 3.365 M acid concentration and then decrease d with increasing acid concentration. No important effect of stirring speed was observed. The activation energy of the process was determine d to be 51.490 kJ mol(-1). It was determined by graphical and statisti cal methods that the reaction fits a model in the form of -ln(1 - X) = kt. The following semiempirical mathematical model, which expresses t he process well, was established: -ln(1 - X) = 56 664(D)(-1.42)(S/L)(- 0.270) exp(-6193.0/T)t, where X is the conversion fraction, D the part icle size, S/L, the solid-to-liquid ratio, and T the reaction temperat ure.