The model of liquid diffusion in a solid fractal medium is developed by adopting random theory

and thus the relationship of diffusion coefficient between fractal medium and free space is obtained. According to the study and analysis of micro-processes

the reaction mechanism and kinetics of liquid-solid phase which feature phosphoric acid and phosphate ore particles system are revealed. When the reactive components diffuse in the ore particle through a large amount of micro pores

there exist three zones

including penetration zone where reaction has finished

reaction zone where reaction and diffusion happen at the same time

and unreacted zone. With the reaction proceeding

the penetration and reaction zone will move towards the center of the particle. From the above basic point of view

the zone and fractal model of two-phase reaction kinetics model has been put forward.