| A mathematical model for the precipitation of spherical particles has been developed for the growth stage of particles where no further nucleation is accounted for. The applicability of the model has been tested by measuring the rate of precipitation of hydronium jarosite from ferric sulfate solution at elevated temperatures, and the agreement was found to be satisfactory. At the initial period of reaction the rate of hydrolysis is limited by a surface controlled process (activation energy, 8.5 ㎉/㏖), whereas at the latter period that of hydrolysis is controlled by a diffusion process(activation energy, 2.2 ㎉/㏖) in the interfacial layer. The criterion of the operating mechanism is apparently the size of the precipitate particle. It is also interesting to note that the lower the initial concentration of ferric sulfate and also the higher the basicity of solutions, the higher the yield was obtained. |
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