Pennsylvania Mine Research Articles

Assessing the Extractability of Rare Earth Elements from Coal Preparation Fines Refuse Using an Organic Acid Lixiviant

This work is a first-order study to assess the suitability of an organic acid lixiviant to extract rare earth elements (REE) from coal preparation fines refuse sourced from a Pennsylvania mine with a total REE of ~ 300 ppm. The extraction of REE using an organic acid, in this case 0.1 M citric acid and 0.5 M trisodium citrate solution, is compared against 0.5 M (NH4)2SO4, 1 M HCl, 1.2 M H2SO4, and 0.5 M ethylenediaminetetraacetic acid (EDTA). Ashing the coal waste material prior to leaching tests with the citrate solution nominally improved REE extraction. Buffered citrate solution recovered 7% of the total REE in the as-received Isabella Fines as compared to 11% in ashed samples, whereas (NH4)2SO4 extracted 5–6%, respectively. EDTA recovered up to 33% of the total REE, most likely due to the higher coordination chelate bond. Mineral acids, however, outperformed the organic acids on ashed material (16–52% REE recovery), suggesting that organic acids may not be a suitable competitive option for REE extraction from these types of feedstocks.

Long-term Performance and Costs for the Anna S Mine Passive Treatment Systems

AMD from the Anna S coal mine in Pennsylvania (USA) has been treated successfully since 2004 in the Anna and Hunters Drift (HD) passive systems. The systems, which consist of vertical flow ponds and constructed wetlands, are the largest and most costly mine water treatment project installed by a non-profit group in the USA to date. 15 years of monitoring data show that the systems effectively treated 1910 L/min of flow with pH 2.8–3.1 containing 121–330 mg/L acidity (as CaCO3), 11–31 mg/L Al, 6–33 mg/L Fe, and 6 mg/L Mn. The systems produced effluents with pH 7.5, 134–140 mg/L alkalinity (as CaCO3), < 1 mg/L Al, 1 mg/L Fe, 2–3 mg/L Mn, and never discharged water with less than 60 mg/L alkalinity (106 samples). In 15 years of operation, the systems generated a combined 5600 tonnes (t) of net alkalinity. Unit treatment costs were converted to 2018 U.S. $ and compared to active treatment systems. Over a 20 year period, passive systems generate alkalinity at a cost of $1168/t of CaCO3, which is 50% less than unit costs for lime treatment plants currently operated in Pennsylvania.

A Case Study of the Collapse of Slender Pillars Affected by Through-Going Discontinuities at a Limestone Mine in Pennsylvania

The sudden collapse of approximately 3 Ha of room-and-pillar workings at a limestone mine in southwestern Pennsylvania in 2015 resulted in an air blast that injured three mine workers. Subsequent investigations showed that an area encompassing 35 pillars had collapsed. The pillars were 9-10 m wide and up to 18 m high. A notable geologic feature is the through-going joints that dip at 50-80° and can extend from the roof to the floor of the pillars. These structures are thought to have weakened the pillars well below the strength that is predicted by empirical equations for hard-rock pillar design. This paper presents the relevant geotechnical data related to the collapsed area and numerical model results that were used to estimate the pillar loading underneath the variable topography, and compares the pillar loads to some established hard-rock pillar strength equations. The outcome is also compared to a strength equation that was developed specifically for limestone mines in which the negative impact of large angular discontinuities is explicitly accounted for. The results show that established hard-rock pillar strength equations do not adequately account for the impact of large through-going discontinuities on the strength of slender pillars. The equations would have significantly overestimated the strength of the pillars at the case study mine. The critical state of the workings would have been predicted correctly by the limestone pillar strength equation that accounts for the large discontinuities.

Non-invasive flow path characterization in a mining-impacted wetland

Time-lapse electrical resistivity (ER) was used to capture the dilution of a seasonal pulse of acid mine drainage (AMD) contamination in the subsurface of a wetland downgradient of the abandoned Pennsylvania mine workings in central Colorado. Data were collected monthly from mid-July to late October of 2013, with an additional dataset collected in June of 2014. Inversion of the ER data shows the development through time of multiple resistive anomalies in the subsurface, which corroborating data suggest are driven by changes in total dissolved solids (TDS) localized in preferential flow pathways. Sensitivity analyses on a synthetic model of the site suggest that the anomalies would need to be at least several meters in diameter to be adequately resolved by the inversions. The existence of preferential flow paths would have a critical impact on the extent of attenuation mechanisms at the site, and their further characterization could be used to parameterize reactive transport models in developing quantitative predictions of remediation strategies.

Estimating instream constituent loads using replicate synoptic sampling, Peru Creek, Colorado

Summary The synoptic mass balance approach is often used to evaluate constituent mass loading in streams affected by mine drainage. Spatial profiles of constituent mass load are used to identify sources of contamination and prioritize sites for remedial action. This paper presents a field scale study in which replicate synoptic sampling campaigns are used to quantify the aggregate uncertainty in constituent load that arises from (1) laboratory analyses of constituent and tracer concentrations, (2) field sampling error, and (3) temporal variation in concentration from diel constituent cycles and/or source variation. Consideration of these factors represents an advance in the application of the synoptic mass balance approach by placing error bars on estimates of constituent load and by allowing all sources of uncertainty to be quantified in aggregate; previous applications of the approach have provided only point estimates of constituent load and considered only a subset of the possible errors. Given estimates of aggregate uncertainty, site specific data and expert judgement may be used to qualitatively assess the contributions of individual factors to uncertainty. This assessment can be used to guide the collection of additional data to reduce uncertainty. Further, error bars provided by the replicate approach can aid the investigator in the interpretation of spatial loading profiles and the subsequent identification of constituent source areas within the watershed. The replicate sampling approach is applied to Peru Creek, a stream receiving acidic, metal-rich effluent from the Pennsylvania Mine. Other sources of acidity and metals within the study reach include a wetland area adjacent to the mine and tributary inflow from Cinnamon Gulch. Analysis of data collected under low-flow conditions indicates that concentrations of Al, Cd, Cu, Fe, Mn, Pb, and Zn in Peru Creek exceed aquatic life standards. Constituent loading within the study reach is dominated by effluent from the Pennsylvania Mine, with over 50% of the Cd, Cu, Fe, Mn, and Zn loads attributable to a collapsed adit near the top of the study reach. These estimates of mass load may underestimate the effect of the Pennsylvania Mine as leakage from underground mine workings may contribute to metal loads that are currently attributed to the wetland area. This potential leakage confounds the evaluation of remedial options and additional research is needed to determine the magnitude and location of the leakage.

MiniSipper: A new in situ water sampler for high-resolution, long-duration acid mine drainage monitoring

Abandoned hard-rock mines can be a significant source of acid mine drainage (AMD) and toxic metal pollution to watersheds. In Colorado, USA, abandoned mines are often located in remote, high elevation areas that are snowbound for 7–8months of the year. The difficulty in accessing these remote sites, especially during winter, creates challenging water sampling problems and major hydrologic and toxic metal loading events are often under sampled. Currently available automated water samplers are not well suited for sampling remote snowbound areas so the U.S. Geological Survey (USGS) has developed a new water sampler, the MiniSipper, to provide long-duration, high-resolution water sampling in remote areas. The MiniSipper is a small, portable sampler that uses gas bubbles to separate up to 250 five milliliter acidified samples in a long tubing coil. The MiniSipper operates for over 8months unattended in water under snow/ice, reduces field work costs, and greatly increases sampling resolution, especially during inaccessible times.MiniSippers were deployed in support of an U.S. Environmental Protection Agency (EPA) project evaluating acid mine drainage inputs from the Pennsylvania Mine to the Snake River watershed in Summit County, CO, USA. MiniSipper metal results agree within 10% of EPA-USGS hand collected grab sample results. Our high-resolution results reveal very strong correlations (R2>0.9) between potentially toxic metals (Cd, Cu, and Zn) and specific conductivity at the Pennsylvania Mine site. The large number of samples collected by the MiniSipper over the entire water year provides a detailed look at the effects of major hydrologic events such as snowmelt runoff and rainstorms on metal loading from the Pennsylvania Mine. MiniSipper results will help guide EPA sampling strategy and remediation efforts in the Snake River watershed.

BATTLING BAT FUNGUS

AS MICROBIOLOGIST Hazel A. Barton of Northern Kentucky University descended into the cool, damp, pitch-black darkness of an abandoned iron mine in Pennsylvania, she switched on the LED lamp on her helmet just as she had hundreds of times before and prepared to take stock of another subterranean ecosystem. But she started getting an uneasy feeling that something wasn’t right. “It’s hard to describe,” Barton says. “But it felt evil.” As she continued into the mine, last worked a century ago, Barton realized her premonition was right. Everywhere she looked, bat bodies were covered with white fungus. “The bats flying around were zombies,” she says. “On the cave floor, there were hundreds of bat carcasses. Because they decompose quickly, there were piles of bones with loose flesh. In some places, it was just a brown, sludgy mass.” It turns out that the fast-spreading fungal disease, named white-nose syndrome for the visually striking white Geomyces destructans ...

Reinforcing Coal Mine Roof with Polyurethane Injection: 4 Case Studies

NIOSH has recently completed a study of the interaction between polyurethane (PUR) and coal mine roof in order to determine the mechanism of reinforcement, in both highly fractured rock and unfractured rock. Four case studies of PUR reinforcement are presented. At a West Virginia site, a borehole camera revealed the location of roof voids and guided the PUR injection. By injecting polyurethane into a zone from 0.6 to 1.8 m (2–6 ft.) high in the roof, a roof beam was created and ongoing intersection falls were halted. In another highly fractured roof in a western Pennsylvania mine, a total of 5.8 cm (2.3 in.) of rubbleized rock was found in a zone up to 3 m (10 ft.) into the roof. Untargeted PUR injection filled approximately 1/2 of the fractures. These two case studies showed that it is not necessary to fill up 100% of the void space to create stability. In the other two field sites, polyurethane was injected into weak, but unfractured roof. Post-injection video monitoring showed that weak bedding planes were hydraulically wedged open and polyurethane injected along bedding. The reinforcement value of this injection method is limited because of the wafer-thin layer of PUR introduced along bedding, and the lack of a PUR “webbing” which would serve as a structural framework to provide strength. It was determined that video inspection prior to PUR injection can aid in identifying the fracture zones to target, and minimize “blind” pumping and loss of PUR.

Mourning “Men Joined in Peril and Purpose”: Working-Class Heroism in News Repair of the Sago Miners’ Story

Initially promising to replicate the story of the 2002 rescue at the Quecreek mine in Pennsylvania, news coverage of the January 2006 coal mine accident in Sago, WV, went terribly wrong when journalists incorrectly reported the miners’ “miracle” survival. Analysis of 761 newspaper, newsmagazine, and broadcast news reports illustrates how journalists corrected a mishandled story, and offers a glimpse into their broader role in constructing politically affirming national mythology. The final story of Sago was one of a rural community with class pride, distinct gender roles, and other “traditional” values presumed lost—a nostalgic parable of blue-collar patriotic sacrifice.

Evaluation of Seat Designs Relative to Transmitted Vehicle Vibration on Underground Mine Transport Vehicles

The National Institute for Occupational Safety and Health (NIOSH) researchers have investigated seat design issues for the occupants and operators of underground mine transport vehicles relative to whole-body vibration (WBV) and mechanical shock. Considering the ergonomic and engineering improvements made to underground mine shuttle car seats, this study has focused on reducing injury risk by improving seating on transport vehicles such as scoops, mantrips, personnel carriers, and rail-mounted locomotives. Similarly, proposed seat design improvements included layering of various types of viscoelastic foam padding to isolate vehicle occupants and operators from adverse health effects of jarring/jolting exposure. This paper discusses the results obtained from laboratory vibration testing of new seat padding materials in seven configurations at the NIOSH – Pittsburgh Research Laboratory (PRL) showing that careful use of configuration and materials can reduce the operator's exposure to WBV. In addition, results for four mine transport vehicles are presented from field data collection efforts at a Southwestern Pennsylvania mine showing that a NIOSH based design does reduce the operator's exposure to WBV. Finally, the authors discuss efforts to develop and field test seat padding interventions using new padding materials and configurations based on the laboratory test results [The findings and conclusions in this report are those of the author(s) and do not represent the views of the National Institute for Occupational Safety and Health.]

Nutrient and Trace Element Leaching following Mine Reclamation with Biosolids

Mine reclamation with biosolids increases revegetation success but nutrient addition well in excess of vegetation requirements has the potential to increase leaching of NO3 and other biosolids constituents. A 3-yr water quality monitoring study was conducted on a Pennsylvania mine site reclaimed with biosolids applied at the maximum permitted and standard loading rate of 134 Mg ha(-1). Zero-tension lysimeters were installed at 1-m depth 1 yr before reclamation: three in the biosolids application area, one in a control area (no biosolids). Before reclamation, all water samples had pH in the range 4.7 to 6.2, acidity < 20 mg L(-1), and very low levels of all other measured parameters. Following reclamation, percolate water in the biosolids-treated area had lower pH and greater acidity than the control area. Acidity was greatest during the first winter following biosolids application, decreased during the spring, and showed a similar pattern but with much smaller concentrations the second year. Maximum first- year leachate NO3 concentrations were approximately 300 mg L(-1) and half as large the second year. Estimated inorganic N leaching loss during the first 2 yr after biosolids application was 2327 kg N ha(-1). Aluminum, Mn, Cu, Ni, Pb, and Zn followed similar leaching patterns as did acidity, and their mobilization appeared to be the result of the increased acidity. These results indicate that large applications of low-C/N-ratio biosolids could negatively impact area water quality and that biosolids reclamation practices should be modified to reduce this possibility.

Geochemical evolution of solutions derived from experimental weathering of sulfide-bearing rocks

The chemical composition of natural waters is affected by the weathering of geologic materials at or near the surface of the Earth. Laboratory weathering experiments of whole-rock sulfide rocks from the Shoe-Basin Mine (SBM) and the Pennsylvania Mine (PM) from the Peru Creek Basin, Summit County, Colorado, indicate that the mineral composition of the sulfide rocks, changes in pH, the duration of the experiment, and the formation of sorbents such as Fe and Al oxyhydroxides affect the chemical composition of the resulting solution. Carbonate minerals in the rock from SBM provide buffering capacity to the solution, contribute to increases in the pH and enhance the formation of Fe and Al oxyhydroxides, which sorb cations from solution. The final solution pH obtained in the experiments was similar to those measured in the field (i.e., 2.8 for PM and 5.0 for SBM). At PM, acidic, metal-rich mine effluent is discharged into Peru Creek where it mixes with stream water. As a result, the pH of the effluent increases causing Fe and Al oxyhydroxide and schwertmannite to precipitate. The resulting solids sorb metal cations from the water thereby improving the quality of the water in Peru Creek.

Characterization of limestone reacted with acid-mine drainage in a pulsed limestone bed treatment system at the Friendship Hill National Historical Site, Pennsylvania, USA

Armoring of limestone is a common cause of failure in limestone-based acid-mine drainage (AMD) treatment systems. Limestone is the least expensive material available for acid neutralization, but is not typically recommended for highly acidic, Fe-rich waters due to armoring with Fe(III) oxyhydroxide coatings. A new AMD treatment technology that uses CO 2 in a pulsed limestone bed reactor minimizes armor formation and enhances limestone reaction with AMD. Limestone was characterized before and after treatment with constant flow and with the new pulsed limestone bed process using AMD from an inactive coal mine in Pennsylvania (pH=2.9, Fe =150 mg/l, acidity =1000 mg/l CaCO 3). In constant flow experiments, limestone is completely armored with reddish-colored ochre within 48 h of contact in a fluidized bed reactor. Effluent pH initially increased from the inflow pH of 2.9 to over 7, but then decreased to <4 during the 48 h of contact. Limestone grains developed a rind of gypsum encapsulated by a 10- to 30-μm thick, Fe-Al hydroxysulfate coating. Armoring slowed the reaction and prevented the limestone from generating any additional alkalinity in the system. With the pulsed flow limestone bed process, armor formation is largely suppressed and most limestone grains completely dissolve resulting in an effluent pH of >6 during operation. Limestone removed from a pulsed bed pilot plant is a mixture of unarmored, rounded and etched limestone grains and partially armored limestone and refractory mineral grains (dolomite, pyrite). The ∼30% of the residual grains in the pulsed flow reactor that are armored have thicker (50- to 100-μm), more aluminous coatings and lack the gypsum rind that develops in the constant flow experiment. Aluminium-rich zones developed in the interior parts of armor rims in both the constant flow and pulsed limestone bed experiments in response to pH changes at the solid/solution interface.

Effect of Sewage Sludge on Formation of Acidic Ground Water at a Reclaimed Coal Mine

AbstractData on rock, ground water, vadose water, and vadose gas chemistry were collected for two years after sewage sludge was applied at a reclaimed surface coal mine in Pennsylvania to determine if surface‐applied sludge is an effective barrier to oxygen influx, contributes metals and nutrients to ground water, and promotes the acidification of ground water. Acidity, sulfate, and metals concentrations were elevated in the ground water (6‐ to 21‐m depth) from spoil relative to unmined rock because of active oxidation of pyrite and dissolution of aluminosilicate, carbonate, and Mn‐Fe‐oxide minerals in the spoil. Concentrations of acidity, sulfate, metals (Fe, Mn, Al, Cd, Cu, Cr, Ni, Zn), and nitrate, and abundances of iron‐oxidizing bacteria were elevated in the ground water from sludge‐treated spoil relative to untreated spoil having a similar mineral composition; however, gaseous and dissolved oxygen concentrations did not differ between the treatments. Abundances of iron‐oxidizing bacteria in the ground water samples were positively correlated with concentrations of ammonia, nitrate, acidity, metals, and sulfate. Concentrations of metals in vadose water samples (&lt;5‐m depth) from sludge‐treated spoil (pH 5.9) were not elevated relative to untreated spoil (pH 4.4). In contrast, concentrations of nitrate were elevated in vadose water samples from sludge‐treated spoil, frequently exceeding 10 mg/L. Downgradient decreases in nitrate to less than 3 mg/L and increases in sulfate concentrations in underlying ground water could result from oxidation of pyrite by nitrate. Thus, sewage sludge added to pyritic spoil can increase the growth of iron‐oxidizing bacteria, the oxidation of pyrite, and the acidification of ground water. Nevertheless, the overall effects on ground water chemistry from the sludge were small and probably short‐lived relative to the effects from mining only.

Amelioration of the toxicity of H+ to larval stoneflies by metals found in coal mine effluent

Stonefly nymphs (Acroneuria carolinensis) were used as a bioindicator of the toxicity of coal mine drainage, and of the interaction between low pH and dissolved metals at severe pollutant levels. Laboratory experiments were done to determine the mean life expectancy of stoneflies subjected to simulated mine drainage with various levels of metals and pH. Both iron and aluminum had significant protective effects against low pH toxicity (at levels found in mine drainage streams of pH 2.8–3.3). The ameliorative effect of Al and Fe was additive. At pH 2.8, the protective effect of aluminum increased with concentration, approaching a maximum near 12 mM. Increased water hardness due to Ca and Mg had a lesser protective effect. A laboratory simulation of a field site at pH 2.8 (modelling field levels of Na, K, Mg, Ca, Al, and Fe) was more toxic than the field site it was patterned after, indicating that there is an ameliorating factor that is not among the ions considered. The other metals tested (Mn, Zn, Cu, and Cd at concentrations prevalent in central Pennsylvania mine effluent) did not reduce the toxicity of H+ ions at pH 3.3. Stonefly nymphs placed in an acid mine drainage stream with a pH of 4.0, lost approximately 50% of their body sodium. However, when these field water chemistry conditions were mimicked in the laboratory there was no significant body Na loss. This indicates that some factor(s) other than the cations considered is affecting toxicity, and that field conditions were more toxic than the laboratory simulation at pH 4.0. Larval stoneflies are more tolerant of acidic mine effluent than are trout. Hence, they can be a useful bioindicator of the toxicity of severe acid and metal mixtures, especially when enough detail to understand the mechanisms is sought.

Mine controls bad roof with trusses bolted on cycle : Barish, K Coal AgeV90, N5, May 1985, P62–66

Roof conditions deteriorated in a drift mine in Pennsylvania, and timber, steel, 10 ft roof bolts and resin bolts used in combination proved unsuccessful for roof control. A truss system of rods in tension was finally found satisfactory and was installed on-cycle using modified roof-bolting machines. An account is given of the application of the method.

Coal Workers' Pneumoconiosis: In vitro study of the chemical composition and particle size as causes of the toxic effects of coal

Cells grown in vitro are inhibited to a greater extent by leachates of coal particles from a mine in Pennsylvania where the miners have a high incidence of Coal Workers' Pneumoconiosis than by leachates of coal of the same particle size but from a mine in Utah where the miners show a low prevalence of the disease. Leachates of respirable particles (1.5 μm and less) of the two coals caused markedly different responses in the cell culture system. The leachate from the Pennsylvania coal caused a growth depression while chemicals leached from the same size particles of the Utah coal stimulated cell growth. The concentration of selected metals in the leachates of the two coal samples differed. The results support the hypothesis that toxic substances leached from coal may be a factor in the etiology of CWP.

The Concentration of Cd, Cu, Fe. Ni, Pb, and Zn in Bituminous Coals from Mines with Differing Incidences of Coal Workers' Pneumoconiosis

A detailed study of the analysis of Cd, Cu, Fe, Ni, Pb and Zn content in bituminous coals from Pennsylvania and Utah was made and a satisfactory procedure for their analysis is presented. The Cu, Fe, Ni, Pb and Zn content of coal from a Pennsylvania mine having a high incidence of Coal Workers' Pneumoconiosis (CWP) was found to be higher than a sample of coal from a Utah mine of low disease incidence. The cadmium content was found to be the same in both coals. The present investigation also deals with some observations concerning interferences associated with coal analysis using atomic absorption spectrophotometric methods. The significance of data with regard to the change in metal levels found in coal miners' lungs is discussed.

Isolation of metal-binding agents from coal dust and their effects on mitochondrial function.

Abstract Bituminous coal samples from mines in Utah and Pennsylvania were extracted with a series of organic solvents, used in order of increasing polarity. The extracted materials, amounting to 58–70 mg/g of Utah coal and 12–15 mg/g of Pennsylvania coal, were each fractionated on a carboxymethyl cellulose column in the Cu (II) form. The copper-complexing fractions for Utah and Pennsylvania were 30% and 22%, respectively, of the total extract. Copper-binding capacity was 400 ug copper/g Utah coal and 40 ug/g for Pennsylvania. The copper-binding ligands from both coals uncoupled oxidative phosphorylation of isolated rat liver mitochondria, a system containing copper and iron metalloenzymes. The inhibitory activity per gram of extracted material was higher for Pennsylvania than Utah. These results suggest that the extraction and absorption of metal-binding agents from coal may adversely alter vital cellular energetics. Coal dust and its effects on human health is of concern because of the prevalence of respiratory disorders incurred by coal mine workers. In epidemiological studies it has been found that 10% of working miners showed definite radiological evidence of pneumoconiosis. Another survey revealed that nearly 50% of working miners suffered from some degree of dyspnea. Several investigators are studying the effects of coal as a particle. However, in the present study coal dust is being investigated as a carrier of chemicals. Coal dust has been shown to contain significant amounts of heavy metals such as Fe, Ni, Al, Cd, Pb, and many others. In this paper we are concerned with the nature of the organic chemicals in coal, particularly in the presence of metal-binding agents. It is our contention that metal-binding ligands in coal (if extractable and absorbed) may interfere with trace metal metabolism by interacting with essential trace metals. In this manner, they may act as metalloenzyme inhibitors and thus may play an important role in health effects such as pulmonary, cardiovascular, neoplastic, and collagen diseases in which alterations of trace metal metabolism have been implicated. Metal-binding agents have been isolated from tobacco smoke condensate and from the smoke of other burned vegetable matter. These constituents were found to inhibit several metalloenzymes, i.e., galactose oxidase and catalase as well as to inhibit the in vitro function of copper-and iron-requiring biological systems such as respiratory activity of rat liver slices and uncoupling of rat liver mitochondria (V. Elia, unpublished results). Therefore, the goal of this study was a) to devise a method for extraction of coal dust; b) to establish whether the extracts contain metal-binding agents; and c) to obtain evidence that these agents may interfere with trace metal metabolism or act as inhibitors of metalloenzyme-requiring biological systems. Two types of bituminous coal, one obtained from a mine in Pennsylvania and the other from a mine in Utah were examined. The Pennsylvania coal is a harder variety, contains more heavy metals, and causes higher incidence of coal miner's pneumoconiosis in comparison to the Utah coal.