Characterization of mine waste at the Elizabeth Copper Mine, Orange County, Vermont

Abstract

Figure 1. Copperas Brook confluence with the West Branch of the Ompompanoosuc River, about 0.5 km downstream from the base of the tailings at the Elizabeth mine site. The distinctive orangered color of iron-rich coatings on the streambed and river rock is a hallmark of acid mine drainage. The U.S. Geological Survey is currently (1999) cooperating with the Elizabeth Mine Study Group to characterize acid mine drainage from the site (Seal and others, 1999) as part of a broader study of the environmental behavior of massive sulfide deposits. Preliminary USGS water quality data are included in a report on hydrologic characterization and reclamation options prepared for the Elizabeth Mine Study Group (Barg and others, 1999). The water data show elevated concentrations of dissolved iron, aluminum, and acidity downstream from the tailings. Preliminary evaluation suggests that the heavy metals copper, zinc, and cadmium exceed U.S. EPA guidelines for acute toxicity for aquatic ecosystems (Seal and others, 1999). Increased metal loads from dissolution of sulfate salts during storm events degrade the water quality and aquatic biology of Copperas Brook. In conjunction with the USGS water quality study, the site was visited in August, 1998, and different geologic materials were sampled to characterize the mineralogy and chemistry of solid phases. Mineralogy is an important control on water chemistry because the primary minerals in ore and host rock, and the secondary minerals that form during weathering of ore and tailings, provide the source for metals and acidity in associated waters. Soluble efflorescent sulfate salts forming on mine dump soils and tailings piles at Elizabeth are an important source of metals that affect surface runoff from the extensive mine waste on short time scales. Host rocks and mine waste composed mainly of common rock-forming minerals such as mica and feldspar release aluminum upon weathering and some of the minerals, although less effective than carbonate minerals, can consume some acidity. Results of field observations and measurements, mineralogic data, and geochemical analyses for samples collected at Elizabeth in 1998 are summarized in this report, preceded by a general overview of environmental signatures associated with massive sulfide deposits elsewhere. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and electron microprobe analysis (EMPA) were used to identify the minerals; mineralogic and geochemical data are used to track the distribution of metals during weathering. These data provide preliminary information about the mineralogic residence, concentrations, and spatial distributions of metals and other elements in the solid materials on the site after 50 years (or more) of weathering and oxidation. Together with water analyses, these data can be used to help focus plans for site reclamation by providing information on the character of materials impacting Copperas Brook from the Elizabeth mine site. ENVIRONMENTAL SIGNATURES OF MASSIVE SULFIDE DEPOSITS Besshi-type massi...

Geochemical Characterization of Mine Waste From the Pike Hill Superfund Site in Vermont, Usa

“…11). The anomalous concentration of Se in the partially-burnt flotation-mill tailings (04PKHL9) is consistent with anomalously high Se concentrations in partially-roasted waste rock at the Elizabeth mine (Hammarstrom et al, 1999). This sample also contains the highest concentration of S. The composition of mine waste including waste rock and unoxidized tailings from the Elizabeth (Eliz) and Ely mines are shown as the blue colored area in the background (Hammarstrom et al, 2001(Hammarstrom et al, , 2003Piatak et al, 2004).…”

Role of microbial iron reduction in the dissolution of iron hydroxysulfate minerals

“…[19] The release of the jarosite structural ions (iron, sulfate, and potassium) observed in this study (Figure 1) indicates that metals or radionuclides substituted at these structural positions might also be released by microbial Fe(III) reduction under anoxic conditions at neutral pH. By their physical nature, jarosite and related iron minerals precipitating in tailings ponds [Schuiling and van Gaans, 1997] and streambeds [Hammarstrom et al, 2000] can form crusts or hardpans that seal the sediment-water interface and limit oxygen penetration to underlying materials, thus promoting the development of anoxic conditions. Although jarosite may be formed and perhaps initially disposed of in oxic environments, it may be subsequently transported to anoxic environments by erosion and burial; for example, dewatered UMT containing jarosite-bound 226 Ra can be eroded from surface impoundments and redeposited in anoxic, downstream wetlands.…”

“…A distinct color change occurred in treatments with cells at 30°C after 24 h; the solid material, originally golden yellow, became a deep rust‐colored orange. The stoichiometry of Fe +3 :SO 4 +2 :K +1 in the starting material was 3:2:0.6 on the basis of chemical analyses by Hammarstrom et al [2000], while the release to solution calculated after incubation with G. metallireducens was 0.37:2:0.59. The control treatment with cells incubated at 4°C produced comparatively little Fe +2 .…”

“…Mineralogy was determined by X‐ray diffraction (XRD) on an automated diffractometer using CuKα radiation, as described by Hammarstrom et al [2000]. Both the Utah and Elizabeth Mine jarosite spectra were dominated by the following diagnostic peaks (reported as d spacing (and Miller index of plane hkl )) 2.29 Å ( 107 ), 3.08 Å ( 021 ), 3.11 Å ( 113 ) [ Brown , 1961].…”

“…Schwertmannite [Fe 8 O 8 (OH) 6 (SO 4 )], informally known as “yellowboy”, is a poorly crystalline mineral with a high specific surface area, structurally similar to either akaganeite [ Bigham et al , 1994] or ferrihydrite [ Loan et al , 2004]. It occurs as an ochreous precipitate from acid, sulfate‐rich waters [ Bigham et al , 1994; Hammarstrom et al , 2000], such as acidic mine‐drainage environments, often coprecipitating with jarosite or goethite. Few studies of metal accumulation by schwertmannite have been done.…”