Figure 5

(A) Partially reacted particle and (B) X-ray map. Figure 5A shows a partially decomposed particle made of a gel halo, a reaction front and an unreacting core. Figure 5B shows the mapping performed on the partially decomposed particle. In the part showing the gel halo it can be observed how K and S have diffused from the particle into the solution, and are present only in the unreacting core. Fe and As are distributed throughout the particle. Previous studies have reported that the arsenic remains in the solids of the alkaline decomposition of arsenical natrojarosite [19].