The behaviour of gallium during jarosite precipitation

The behaviour of gallium during the precipitation of jarosite-type compound s from Fe(SO4)(1.5)M2SO4 solutions (where M is Na, K or NH4) was investigat ed. Gallium is readily precipitated in jarosite-type compounds and the exte nt of gallium precipitation increases as the Ga concentration of the soluti on increases. The Ga3+ ion replaces Fe3+ in the jarosite structure to form a nearly ideal solid solution series. The molar partitioning coefficient, ( Ga/Ga+Fe)(solid):(Ga/Ga+Fe)(Solution) is approximately one for the Na-, K- and NH4- jarosite species studied. Solution pH exerts a major influence on the amount of Ga-bearing jarosite formed, but has a lesser effect on the pr oduct composition. In particular, higher pH values slightly enhance the pre cipitation of Ga relative to Fe. Increasing ZnSO4 concentrations have a neg ligible effect on the amount of product formed or its Ga content. Longer re tention times significantly increase the amount of precipitate formed, but have only a minor effect on the composition of the Ga-bearing sodium jarosi te product. Increasing concentrations of Fe(SO4)(1.5) in the presence of a constant Ga(SO4)(1.5), concentration proportionally increase the amount of product and result in a consequential dilution of its Ga content. A compari son with previously published results for indium shows that both gallium an d indium behave similarly during the precipitation of jarosite-type compoun ds.