OP-II-3

OP-I-1have opened a new perspective: the particle becomes visible and competing modelscan be excluded on the basis of direct observations.It has been shown in the present work that the surface area of a solid phase (A)can be expressed with a generalized equationincorporated into a rate equation e.g.dcdtAA =aMρ RPyA B0nx 1−x0 n, which can further be= −kAc , where R 0 is the characteristicdimension of the solid particle in the beginning of the reaction (radius of a sphere orinfinite cylinder, half-thickness of a slab), n 0 and n denote the amount of solidsubstance at t=0 and at an arbitrary reaction time, respectively. M and ρ are themolar mass and density of the solid material, respectively. The shape factor (a=1/x)APis defined accordingly a = R0,where AVp and V p are the surface area and volumePof the particle.Although reactions between solids and liquids, and more specifically dissolutionprocesses have been intensively studied the rigorous treatment of dissolution kineticsis far from complete. In the present work the dissolution kinetics of several industriallyrelevant reactions (leaching of zinc from sphalerite utilizing ultrasound for reactionenhancement; dissolution of boehmite and gibbsite in sodium hydroxide) wasstudied. The experimental data for different cases and the results of kinetic modelingwill be presented.References[1]. T.O. Salmi, J.-P. Mikkola, J. Wärnå, Chemical Reaction Engineering and Reactor Technology,CRC Press, 2010.38