Characterization of Iron Oxides From Abandoned Mine Drainage Discharges

Abstract

This study characterizes mine-drainage derived iron oxides as a precursor for the determination of potential reuses in sustainable water treatment processes. Pure iron oxides have been established as an effective sorptive media or coating for water treatment, yet iron oxides from mine drainages have largely been ignored as a source for this raw material. In addition to passive mine drainage treatment systems, environmental discharges of mine water and associated iron deposits were also examined. In total 13 sources of iron oxides were collected, these sources include 12 coal mining related discharges and one hard rock mining discharge. Water quality and dissolved metals data for the mine water were analyzed to aid in correlating site specific mine water conditions and dominant form of iron oxide present at each location. The iron characterization consisted of X-ray diffraction (XRD) analysis to determine the dominant form of iron, Munsell color classification, particle density, loss on ignition (LOI) to estimate organic matter, scanning electron microscopy (SEM) analysis to determine individual particle size, dry sieve particle size distribution (PSD) to attain ASTM particle size classifications, Brunauer-Emmett-Teller (BET) analysis of surface area, acid oxalate digestions (AOD) to determine the percent of crystalline and non-crystalline material, and inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis for metal concentrations in each iron oxide sample. Observed ranges of selected parameters are: Munsell color (5YR-10YR); particle density (1.97-3.04 g/cm 3); LOI (0.59-1.41%); SEM of smallest individual particles (5-20 nm); BET surface area (63.75-497.02 m 2 /g); AOD (13.52-96.31% non-crystalline material); and the iron content obtained from ICE-OES analysis ranged from (47 to 94% as goethite). The information gained through this detailed characterization of mine-drainage derived iron oxides may eventually aid in the future selection of appropriate iron oxides for sustainable reuse in water treatment processes.

Potential Anionic Sorbent Use of Iron Oxides From Abandoned Mine Drainage Discharges

“…The sampling locations of Gowen Battle Seep and Panola Seep #2 both exist as environmental discharges where the base soil likely contained both silica and clay. This suggestion is supported by the high Al content of the iron precipitates from these locations (MR < PS2 < BS) as shown in Neely and Nairn (2010). Additionally, it is worth noting that characteristic XRD peaks of various clays and quartz were observed to exist in most of the samples, showing increased intensity counts for Battles Seep, Leboskey, Panola Seep #2, GCI, and Gowen Confluence (additional mine drainage derived iron oxides analyzed in the previously mentioned Neely and Nairn 2010 study).…”

“…Interestingly the Mayer Ranch sample was nearest to the pH pzc range of pure goethite even though it contained elevated levels of trace metal such as Zn, Cd, and As previously reported in Neely and Nairn (2010). The presence of impurities associated with the structure and configuration of surface charging is known to influence the point of zero charge possessed by an oxide/hydroxide (Pechenyuk, 1999).…”

Potential Anionic Sorbent Use of Iron Oxides from Abandoned Mine Drainage Discharges

“…The physical/chemical characteristics of Bayoxide E33 P displayed in Table 1 were obtained from the material safety data sheet provided by the manufacturer, LANXESS. A previous study performed by Neely and Nairn (2010) provides a detailed account of the methods used for sample collection, preparation, and characterization of 13 mine drainage derived iron oxides, including the three iron oxides used in this study. Water quality and dissolved metals data for the 13 mine water sources (12 coal and one hard rock) were analyzed to aid in correlating site specific mine water conditions and dominant forms of iron oxide present at each location.…”