Effects of arsenic incorporation on jarosite dissolution rates and reaction products

Synthesis, characterization and thermochemistry of synthetic Pb–As, Pb–Cu and Pb–Zn jarosites

“…The dissolution/transformation reactions of arsenic containing jarosites are much more complex. A recent study (Kendall et al, 2013) indicates that arsenic containing jarosites have incongruent dissolution. Future work is needed to undestand the processes between arsenic and jarosite type minerals.…”

Jarosite versus Soluble Iron-Sulfate Formation and Their Role in Acid Mine Drainage Formation at the Pan de Azúcar Mine Tailings (Zn-Pb-Ag), NW Argentina

“…The concentration of these elements increases at the beginning of the wet season (T3) by the dissolution of the efflorescent salts rich in SO 4 , Fe, Zn, Al, and Ca (copiapite, coquimbite, rhomboclase, alunogen, szomolnokite, gypsum, and Zn-rich melanterite) formed in DC2 during the dry season (Figures 4e and 13a, Process 5). Arsenic content could be provided from the dissolution of jarosite exposed to AMD runoff [35,36] (Figure 13a, Process 6). At the end of the wet season (T4), the pond shows the lowest concentration of sulfate and metals and an increase in its pH value by dilution from rain water.…”

Kinetic Analysis of the Decomposition of the KFe3(SO4)2-x(CrO4)x(OH)6Jarosite Solid Solution in Ca(OH)2Medium

“…Flores et al 48 and Reyes et al 50 found orders of reaction of n = 0 at low [OH − ], which is indicative of inexistent dependence on the reaction medium. In the present work, it is proposed that when there is no dependence on the reaction medium [OH − ], the attack towards the solid particles is done by water, 43 which results in orders of reaction equal to zero and, therefore, much slower reaction rates independent of [OH − ]. The dependence of the chemical rate constant on temperature is given by equation 9 (Arrhenius equation): (9) where k 0 is the frequency factor, E a is the activation energy, R is 8.3144 J mol Table 2.…”

“…28,36,[38][39][40][41][42] Site Z is fully occupied by SO 4 2− in the potassium jarosite, but it can be substituted by varying the amount of chromate until it is completely substituted. 43 It was observed that, the larger the radius of the ions that incorporate in the anionic site, the bigger the difficulty to compete with the SO 4 2− ion. This is the main limiting factor for the incorporation of a larger amount of CrO 4 2− with SO 4 2− still present.…”

“…It was suggested that two dissolution mechanisms can occur: at pH < 3.5 the H + attack is the dominating mechanism, while at pH > 3.5 the OH − attack is the controlling mechanism. Kendall et al 43 suggested a third mechanism for the dissolution rates of jarosites with arsenic. They propose that near the point of zero charge of the jarosite, the dissolution may be controlled by water attack.…”