Particle growth parameters in the precipitation of metastable iron phases from zinc-rich solutions

Agglomeration of metastable iron phases was studied at constant supersaturation in a continuous crystallizer. Specific attention was given to the influence of operating parameters such as pH, temperature, hot iron solution iron concentration, mass of seed, size of seed, stirring rate and viscosity of the iron solution on the agglomeration and quality of ferrihydrite and schwertmannite precipitates. The relative importance of the operating parameters was expressed in terms of the filterability of the solids formed, the change in the particle population density and iron removal efficiency using the so-called Hadamard matrix. The effect of seed addition on the purity of agglomerates was also evaluated.