Assessing the fractionation of scandium, vanadium, and chromium in red mud of West Kalimantan using sequential methods

In this study, the fractionation of scandium (Sc), vanadium (V), and chromium (Cr) was analysed using sequential extraction to evaluate the mobility factors of these metals. The physicochemical characterisation of red mud was conducted for particle size distribution, pH, organic matter content and total metal content using the aqua regia method. The results indicated that red mud had a high pH and low organic matter content and was classified as silt and clay material. The percentage in the exchangeable fraction was V (82.59%), Cr (1.16%), and Sc was not detected, in the carbonate-bound fraction was V (5.69%), and Sc and Cr was not detected. Moreover, the percentages in Fe-Mn oxide-bound fraction were V (2.22%), Sc (26.45%), and Cr (3.48%), in the organic-bound fraction was V (1.33%), Sc (7.97%), and Cr (8.21%), and in the residual fraction was V (8.17%), Sc (65.58%), and Cr (87.15%). Calculating the mobility factor showed that the bioavailability of V was the highest (88.27%) and that of Cr was very low (1.16%). The sequential extraction procedure was successfully applied to assess the fractionation of Sc, V, and Cr in red mud and to provide evidence on the mobility factors of these metals for phytomining applications.