Kinetics of dissolution of Mardin-Mazidagi (Turkey) phosphate ore in dilute phosphoric acid solutions

The dissolution process of phosphate rock from the Semikan area (Mardin-Mazidagi, Turkey) using dilute phosphoric acid has been investigated. The work involved studying the effect of important variables, such as reaction time, stirring speed, particle size fraction, phosphoric acid concentration and temperature. Van der Sluis et al.'s model was used to determine the rate of the partial dissolution of phosphate ore. Mass-transfer coefficients (k(L)) varied between 2.8 and 28.5.10(-3) m.s(-1). The activation energy of the process varied between 16 and 20 kJ.mol(-1). It has been found that the dissolution process is controlled by calcium ion diffusion, rather than by chemical reaction.