Nadine M. Piatak

Mineralogy of mine waste at the Vermont Asbestos Group mine, Belvidere Mountain, Vermont

Abstract Samples from the surfaces of waste piles at the Vermont Asbestos Group mine in northern Vermont were studied to determine their mineralogy, particularly the presence and morphology of amphiboles. Analyses included powder X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and Raman spectroscopy. Minerals identified by XRD were serpentine-group minerals, magnetite, chlorite, quartz, olivine, pyroxene, and brucite; locally, mica and carbonates were also present. Raman spectroscopy distinguished antigorite and chrysotile, which could not be differentiated using XRD. Long-count, short-range XRD scans of the (110) amphibole peak showed trace amounts of amphibole in most samples. Examination of amphiboles in tailings by optical microscopy, SEM, and EPMA revealed non-fibrous amphiboles compositionally classified as edenite, magnesiohornblende, magnesiokatophorite, and pargasite. No fibrous amphibole was found in the tailings, although fibrous tremolite was identified in a sample of host rock. Knowledge of the mineralogy at the site may lead to better understanding of potential implications for human health and aid in designing a remediation plan.

Environmental Characteristics and Utilization Potential of Metallurgical Slag

Slag, an abundant by-product from the pyrometallurgical processing of ores, can be an environmental liability or a valuable resource. The most common environmental impact of slag is from the leaching of potentially toxic elements, acidity, or alkalinity that may impact nearby soils and surface water and groundwater. Factors that influence its environmental behavior include physical characteristics, such as grain size and porosity, chemical composition with some slag being enriched in certain elements, the mineralogy and partitioning of elements in more or less reactive phases, water-slag interactions, and site conditions. Many of these same factors also influence its resource potential. For example, crystalline ferrous slag is most commonly used as construction aggregate, whereas glassy (i.e., granulated) slag is used in cement. Also, the calcium minerals found in ferrous slag result in useful applications in water treatment. In contrast, the high trace-element content of some base-metal slags makes the slags economically attractive for extraction of residual elements. An evaluation tool is used to help categorize a particular slag as an environmental hazard or valuable by-product. Results for one type of slag, legacy steelmaking slag from the Chicago area in the United States, suggest the material has potential to be used for treating phosphate-rich or acidic waters; however, the pH and trace-element content of resulting solutions may warrant further examination.

Copper Speciation in Variably Toxic Sediments at the Ely Copper Mine, Vermont, United States

At the Ely Copper Mine Superfund site, Cu concentrations exceed background values in both streamwater (160-1200 times) and sediments (15-79 times). Previously, these sediment samples were incubated with laboratory test organisms, and they exhibited variable toxicity for different stream sites. In this study we combined bulk- and microscale techniques to determine Cu speciation and distribution in these contaminated sediments on the basis of evidence from previous work that Cu was the most important stressor in this environment and that variable observed toxicity could have resulted from differences in Cu speciation. Copper speciation results were similar at microscopic and bulk scales. The major Cu species in the more toxic samples were sorbed or coprecipitated with secondary Mn (birnessite) and Fe minerals (jarosite and goethite), which together accounted for nearly 80% of the total Cu. The major Cu species in the less toxic samples were Cu sulfides (chalcopyrite and a covellite-like phase), making up about 80-95% of the total Cu, with minor amounts of Cu associated with jarosite or goethite. These Cu speciation results are consistent with the toxicity results, considering that Cu sorbed or coprecipitated with secondary phases at near-neutral pH is relatively less stable than Cu bound to sulfide at lower pH. The more toxic stream sediment sites were those that contained fewer detrital sulfides and were upstream of the major mine waste pile, suggesting that removal and consolidation of sulfide-bearing waste piles on site may not eliminate all sources of bioaccessible Cu.

PROCESSES CONTROLLING GEOCHEMICAL VARIATIONS IN THE SOUTH PIT LAKE, ELIZABETH MINE SUPERFUND SITE, VERMONT, USA

The Elizabeth mine Superfund site offers unique opportunities to investigate the interplay between geochemical and physical processes in the geochemical evolution of an acidic pit lake. The mine exploited a steeply dipping massive sulfide ore body. Ores contained pyrrhotite and chalcopyrite and were hosted by siliciclastic sedimentary rocks and amphibolites. An open pit that accessed part of the ore body is filled by a long (380 m), narrow (< 25 m), and shallow (< 7 m) lake, which is divided into two parts by a rock slide. The southern end serves as a decant point, and discharges for most of the year. Quarterly sampling and continuous temperature monitoring of the water column in the lake document geochemical variations that depend on seasonal variations in the amount of precipitation and the presence or absence of ice. From spring to fall, parameters show limited variation with depth except for temperature, which decreases with depth. The lake experienced overturn in the fall. During winter under ice cover, the lake developed a chemocline shown by a sharp decrease in pH, a doubling of total dissolved solids (TDS), and a ten-fold increase in dissolved Fe with depth (0.4 - 55.2 mg/L). Oxia throughout most of the year causes removal of Fe, but low pH prevents significant sorption of Cu and other metals. Ca (25 - 72 mg/L), Mg (9.6 - 15.0 mg/L), K (6.0 - 8.3 mg/L), Si (6.7 - 9.6 mg/L), and SO4 -2 (210 - 280 mg/L) are the major dissolved constituents during non-stratified ice-free periods; Fe (0.2 - 0.5 mg/L), Al (1.0 - 3.1 mg/L), Cu (0.6 - 1.2 mg/L), and Zn (0.3 - 0.5 mg/L) are important minor dissolved constituents. Throughout the year, the water quality is dependent upon a variety of factors including the geometry of the pit, the short residence time of water within the pit, wind mixing and fall overturn, the oxidation of sulfides on the pit walls and in the unsaturated waste on the floor of the pit south of the haulage way, oxidation of iron within the water column, and mixing of surface waters with high TDS waters entering the bottom of the lake.

Chapter 19 – Environmental Characteristics and Utilization Potential of Metallurgical Slag

Slag, an abundant by-product from the pyrometallurgical processing of ores, can be an environmental liability or a valuable resource. The most common environmental impact of slag is from the leaching of potentially toxic elements, acidity, or alkalinity that may impact nearby soils and surface water and groundwater. Factors that influence its environmental behavior include physical characteristics, such as grain size and porosity, chemical composition with some slag being enriched in certain elements, the mineralogy and partitioning of elements in more or less reactive phases, water-slag interactions, and site conditions. Many of these same factors also influence its resource potential. For example, crystalline ferrous slag is most commonly used as construction aggregate, whereas glassy (i.e., granulated) slag is used in cement. Also, the calcium minerals found in ferrous slag result in useful applications in water treatment. In contrast, the high trace-element content of some base-metal slags makes the slags economically attractive for extraction of residual elements. An evaluation tool is used to help categorize a particular slag as an environmental hazard or valuable by-product. Results for one type of slag, legacy steelmaking slag from the Chicago area in the United States, suggest the material has potential to be used for treating phosphate-rich or acidic waters; however, the pH and trace-element content of resulting solutions may warrant further examination.

Suitability of river delta sediment as proppant, Missouri and Niobrara Rivers, Nebraska and South Dakota, 2015

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Aquatic assessment of the Pike Hill Copper Mine Superfund site, Corinth, Vermont

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WATER QUALITY BEFORE AND AFTER RECLAMATION AT THE ABANDONED VALZINCO Zn-Pb MINE SITE, SPOTSYLVANIA COUNTY, VIRGINIA

The Valzinco deposit was a massive sulfide ore body, dominated by pyrite, sphalerite, galena, and chalcopyrite. It was mined intermittently in the first half of the 20th century by underground methods. The host rocks were metamorphosed felsic volcanic rocks. Mine wastes were dominated by flotation tailings deposited in the stream channel, which were subsequently partially transported downstream by fluvial processes. Acid-base accounting results indicate that the tailings are net acid (net neutralizing potential = -268 to -138 kg CaCO3/tonne) and leach significant quantities of Fe, Al, Zn, Pb, Cu, Cd, and SO4 2- . Pre-reclamation quarterly sampling of the stream below the site documented low- pH waters having elevated concentrations of Fe, Al, Zn, Pb, Cu, Cd, and SO4 2- . Reclamation began in 2001 and major construction was completed in 2002. Reclamation included the removal and encapsulation on site of tailings, application of bactericide, installation of limestone drains, construction of wetlands, and revegetation. Results of recent sampling of the site (June 2007) indicate an increase in pH from 3.4 to 5.1, an increase in hardness of 37 %, and decreases in total dissolved solids (68 %), Fe (94 %), Al (98 %), Zn (77 %), Pb (99.5 %), Cu (97 %), Cd (94 %), and SO4 2- (81 %) relative to mean pre- reclamation values. Even though significant reductions in dissolved metals have been achieved and positive biologic indicators of ecosystem health are present, the concentrations of Cu and Zn remain above hardness-based acute ecosystem toxicity criteria. The elevated concentrations, in part, appear to be a natural, pre- mining characteristic of the watershed. The elevated concentrations also highlight the sensitivity of calculated hardness-based toxicity criteria for soft waters. The hardness-based criteria do not account for the mitigating effect of dissolved organic carbon on metal toxicity in wetland areas such as at Valzinco.

Surface-Water Hydrology and Quality at the Pike Hill Superfund Site, Corinth, Vermont, October 2004 to December 2005

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GEOCHEMICAL CHARACTERIZATION OF MINE WASTE FROM THE PIKE HILL SUPERFUND SITE IN VERMONT, USA 1

The Pike Hill mines Superfund site consists of a group of mines that worked copper-rich Besshi-type massive sulfide deposits. The site contains the abandoned Smith, Eureka, and Union mines and was listed in 2004 as a Superfund site due to aquatic ecosystem impacts. This study is part of a larger project that includes mine waste characterization, surface-water geochemical studies, and documentation of downstream impacts on biota. It is intended to be a precursor to a formal remedial investigation by the U.S. Environmental Protection Agency (USEPA). The goal of this paper is to provide a relative comparison of the various waste piles through characterization of bulk geochemistry, mineralogy, paste pH, acid-base accounting, and metal leachability. In addition, results were compared to similar studies of mine waste from the nearby Ely and Elizabeth Superfund sites. Mine-waste samples at the Pike Hill mines include flotation-mill tailings and waste rock that is composed of fine-grained to boulder- sized host rock and mineralized rock. The waste is primarily composed of silicates, oxides, sulfates, and sulfides, including pyrrhotite, pyrite, chalcopyrite, and sphalerite. Samples locally contain native sulfur and calcite; efflorescent sulfate salts have been observed on waste piles and adit walls. Composite mine- waste samples contain concentrations of Cd, Cu, and Fe that exceed USEPA Preliminary Remediation Goals (PRGs). The concentrations of Se are elevated relative to the average composition of eastern U.S. soils. All mine-waste samples, except the processed flotation-mill tailings, which contain calcite, have paste pH values of 4 or less and negative net-neutralization potentials indicating the samples are acid generating. Twenty-four-hour leachate tests, which use a solution that approximates eastern U.S. precipitation, indicate that potentially toxic trace elements and acidity can be released under simulated weathering conditions. Mine waste at Pike Hill mines is chemically and mineralogically similar to that at the Elizabeth and Ely mines. Also, metals are leached and acid produced in comparable concentrations. Based on the results of this study, mine waste at the Pike Hill Superfund site contaminates soils, is acid generating, and may release potentially toxic metals to streams.