Sequential extraction of chromium, molybdenum, and vanadium in basic oxygen furnace slags

Abstract

Basic oxygen furnace slags (BOS) are by-products of basic oxygen steel production. Whereas the solubility of some elements from these slags has been well investigated, information about the mineralogy and related leaching, i.e., availability of the environmentally relevant elements chromium (Cr), molybdenum (Mo), and vanadium (V), is still lacking. The aim of this study was to investigate these issues with a modified, four-fraction-based, sequential extraction procedure (F1-F4), combined with X-ray diffraction, of two BOS. Extractants with increasing strength were used (F1 demineralized water, F2 CHCOOH + HCl, F3 NaEDTA + NHOH·HCl, and F4 HF + HNO + HO), and after each fraction, X-ray diffraction was performed. The recovery of Cr was moderate (66.5%) for one BOS, but significantly better (100.2%) for the other one. High recoveries were achieved for the other elements (Mo, 100.8-107.9% and V, 112.6-87.0%), indicating that the sequential extraction procedure was reliable when adapted to BOS. The results showed that Cr and Mo primarily occurred in F4, representing rather immobile elements under natural conditions, which were strongly bound into/onto Fe minerals (srebrodolskite, magnetite, hematite, or wustite). In contrast, V was more mobile with proportional higher findings in F2 and F3, and the X-ray diffraction results reveal that V was not solely bound into Ca minerals (larnite, hatrurite, kirschsteinite, and calcite), but also bound to Fe minerals. The results indicated that the total amount of recovery was a poor indicator of the availability of elements and did not correspond to the leaching of elements from BOS.

Reuse and Recycling of By-Products in the Steel Sector: Recent Achievements Paving the Way to Circular Economy and Industrial Symbiosis in Europe

“…In BOF slag, the mineralogy and element availability, such as chromium (Cr), molybdenum (Mo) and vanadium (V), could provide information about its possible environmental impact. A Sequential Extraction Procedure (SEP), four-fraction-based, combined with X-Ray Diffraction (XRD), of two BOF slags has been applied [45]. In particular, the four fractions are: F1 (water soluble), F2 (acid soluble), F3 (reducible) and F4 (residual).…”

Geochemical Characterization of Iron and Steel Slag and Its Potential to Remove Phosphate and Neutralize Acid

“…The solubility of the phases will also influence how much acid neutralization each phase contributes. Lime (CaO) is several orders of magnitude more soluble than CaCO 3 ; in general, calcite is more soluble than the Ca silicates [43,44]. According to experiments on the carbonation of steel slag by Kasina et al [45], the larnite in a steel slag sample was susceptible to dissolution in deionized water, rankinite (Ca 3 Si 2 O 7 ) was dissolved to a lesser degree, and srebrodolskite was insoluble.…”

Steel slag quality control for road construction aggregates and its environmental impact: case study of Vietnamese steel industry—leaching of heavy metals from steel-making slag

“…While there is increasing demand for utilizing steel slag for road construction in Vietnam, due to the lack of national regulations and guidelines, most of the slag remains unutilized and kept in the storage yard in the factory area. On the other hand, there is also the concern about bulk utilization of steel slag may post the signi cant impact to the environment due to leaching of hazardous substances from steel slag matrix, which may become mobile in ground water and soil environment (Chaurand et al 2007;Riley and Mayes 2015;Spanka et al 2018). Because slag is widely re-used as construction materials and environmental application globally, the assessment of environmental aspects of slag would contribute to encourage the utilization of steel slag in Vietnam.…”