Composition and risk assessment of roasted pyrite ash from fertiliser production. (October 2018)

• Record Type: Journal Article
• Authors: Gabarrón, M.; Babur, O.; Soriano-Disla, J.M.; Faz, A.; Acosta, J.A.
• Is Part Of: Chemosphere. Volume 209(2018)
• Page Start: 277
• Page End: 285
• Publication Date: 2018-10
• Subjects: Metal pollution -- Particle size -- Pyrite ash -- Sequential extraction -- Sulphuric acid production; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.06.109
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Pyrite ash is a residue from the roasting of pyrite ores to obtain sulphuric acid used in the fertiliser industry and its production is widely extended worldwide. The mismanagement of this waste may result in environmental and health damages due to its physico-chemical characteristics. The main objective of this study was to examine the physico-chemical and mineralogical composition of roasted pyrite ash from an abandoned fertiliser company, and to evaluate the environmental risk caused by the wind and water dispersion of metals posed by this waste. In order to achieve these objectives, a sequential extraction procedure and a physical fractionation into six size fractions: >100, 100–50, 50–20, 20–10, 10–2.5 and < 2.5 μm were applied. Results showed that pyrite ash is composed mainly of iron-oxides such as hematite (46%) and secondary minerals as anglesite and shows high concentrations of Pb (7464 mg kg −1 ), Zn (2663 mg kg −1 ) and Cu (585 mg kg −1 ). The highest Risk Assessment Code (RAC) values were found for Cd, Pb and Zn, bound to the more labile fractions. Conversely, Pb showed the lowest water solubility due to the covering effect provided by a coating of anglesite in the pyrite ash surface. Most of the metals were associated to both the coarsest (>100 μm) and the finest (2.5–10 μm) fractions, although none represented an environmental risk according to the ecological risk index results. However, 30% of the metals were bound to the respirable fraction (≤100 μm) posing a potential risk for human health and a high potential dispersion by wind to the surrounding areas. Highlights: Variation in metal accumulation depends on the raw material of pyrite ash. Roasting process bounds Zn, Cu, Cd and Ni to labile phases. Pb shows high mobility but low leachability. 60% of metals in pyrite ash are associated with respirable particles. Ecological risk index (RI) does not report risk for the environment by any particle size.