Salt Distribution and Alkalinity Characterization in Bauxite Residue Disposal Areas from the Spatial Scale Range

Bauxite residue (red mud) has high alkalinity and salinity, which seriously restricts its reuse. It is crucial to understand the salt distribution pattern and alkalinity characteristics in the bauxite residue disposal area (BRDA), which can provide a theoretical basis for realizing the salinity and alkalinity regulation and reuse of bauxite residue. In this paper, samples from different locations and depths of the BRDA were used for the determination of soluble salts content, pH, and electrical conductivity (EC), and the correlation between the indicators was analyzed. The results show that bauxite residue has a high content of soluble salts, and the spatial distribution of soluble salts in the BRDA is relatively complex, with moderate variability, but does not show an obvious regularity. The major cations are Na+, K+ and the major anions are CO32-, HCO3-. Through cluster analysis, the soluble ions in bauxite residue can be divided into two main groups, one is Na+, CO32-, HCO3-, and the other is Ca2+, Mg2+, K+, Cl- and SO42-. PH has a significant positive correlation with Na+, K+, CO32- and HCO3-, and a negative correlation with Ca2+. And its alkalinity depends to a large extent on carbonate and bicarbonate, and the Na+ content can be predicted from EC, thus reflecting the concentration of alkaline residues in the bauxite residue.