Quantification of Cr(VI) fractions in COPR under different conditions. “Equilibrium”, “Disequilibrium” and “New equilibrium” show the Cr(VI) partitioning in T-RX in the untreated material, immediately after initial leaching and 400 days after initial leaching and aging under humid conditions. The “Cr(VI) leachable” fraction of the untreated material corresponds to the leaching step of the sequential extraction experiments, while the “Cr(VI) leachable” of the two other materials was determined as part of the equilibration experiment. UV-Vis spectrophotometry was used in all cases for Cr(VI) quantification. In the COPR after 400 days aging, the “Cr(VI) mineral” was calculated as the difference between the “Cr(VI) mineral” in the untreated COPR and the “Cr(VI) leachable” in the “400 days” sample.

Quantification du Cr(VI) dans les charrées de chrome sous les conditions d’« Équilibre », « Déséquilibre » et « Nouvel équilibre », montrant la répartition du Cr(VI) dans le matériau T-RX non traité, immédiatement après le lessivage initial, puis 400 jours après le lessivage initial.