Mineral Composition of Sludge from a Highly Mineralized Alkaline Industrial Waste Settlement Tank

Abstract

The article presents the results of a study of the mineral composition of sediments in a man-made settling pond in Berezniki (Perm Krai, Russia), originating from soda production processes. Along with soda production waste, wastewater from other industries also entered the sedimentation pond. The composition of the accumulated sediment was studied using undisturbed columns. Samples were analyzed using X-ray diffraction and simultaneous thermal analysis (DSC/TG). The mineral composition of the sediments in each layer of all the studied cores is characterized by a predominance of calcite precipitated from wastewater. Along with calcite, due to the presence of magnesium and sodium in the solution, other carbonates—dolomite and sodium (natron)—as well as complex transitional carbonate phases (nortupite and trona)—were also precipitated. Along with carbonate minerals, chloride salts (halite and sylvite), sulfates (gypsum and bassanite), as well as pyrite and native sulfur, were identified. The group of terrigenous minerals is represented by quartz, feldspars, and aluminosilicates. In the lower layers of the sediments, the role of the amorphous phase and non-mineral compounds increased, as determined by thermal analysis. The obtained data on variations in the mineral composition of the sediments provide initial information for selecting methods for the disposal of accumulated waste