Basic oxygen furnace sludge to treat industrial arsenic- and sulfate-rich acid mine drainage

• Published in: Environmental science and pollution research international 2022-05, Vol.29 (25), p.37777-37789
• Main Authors: Araujo, Sandrine F., Caldeira, Cláudia L., Ciminelli, Virginia S. T., Borba, Ricardo P., Rodrigues, Joanna P., Simões, Gustavo F.
• Format: Article
• Language: English
• Subjects: Acid mine drainage; Aquatic Pollution; Arsenates; Arsenic; Atmospheric Protection/Air Quality Control/Air Pollution; Basic converters; Calcium carbonate; Calcium sulfate; Dehydration; Deionization; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Evaluation; Hazardous wastes; Hydrogen peroxide; Iron oxides; Magnesium; Manganese; Mine drainage; Modelling; Oxygen; pH effects; Pollutant removal; Research Article; Sludge; Stability analysis; Sulfates; Waste Water Technology; Water Management; Water Pollution Control; X-ray diffraction
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-021-18120-y

In this study, four systems (S1, S2, S3, and S4) were evaluated to determine whether basic oxygen furnace sludge (BOFS), mainly composed of Fe (84%, mostly as elemental Fe and FeO), Ca (3%, as CaCO 3 ), and Si (1%), is capable of removing As-spiked, Mn, Mg, and sulfate from an industrial acid mine drainage (AMDi) collected in a gold mine in Minas Gerais, Brazil. In the S1 system (BOFS/deionized water pH 2.5), the stability of the residue was evaluated for 408 h under agitation. The results showed that only Ca and Mg were solubilized, and the pH increased from 2.5 up to 11.4 within the initial 24 h and kept still until the end of the experiment (408 h). The S2 system (BOFS/AMDi) achieved 100% removal of As and Mn, and 70% removal of sulfate after 648 h. In the first 30 min, the pH increased from 2.5 to 10, which was maintained until the end of the experiment. The removal of As, Mn, and sulfate in the presence of hydrogen peroxide (S3 and S4 systems — BOFS/AMDi/H 2 O 2 ) was similar to that in the S2 system, which contained only BOFS. The formation of iron oxides was not accelerated by H 2 O 2 . As regards the removal of arsenic and sulfate species, the formation of incipient calcium arsenate and calcium sulfate dehydrated was indicated by X-ray diffraction analysis and PHREEQC modeling. Dissolved manganese and magnesium precipitated as oxides, according to the geochemical modeling. After contact with AMDi, the raw BOFS, initially classified as hazardous waste, became a non-inert waste, which implies simplified, less costly disposal. Except for sulfate, the concentrations of all the other elements were below the maximum permitted levels.