Unmined Areas Research Articles

Cuban Antislavery Narrative in a Postcolonial Light: Anselmo Suárez y Romero's Francisco

Unlike the two iconic Cuban antislavery narratives, Cirilo Villaverde's Cecilia Valdes and Gertrudis Gomez de Avellaneda's Sab, which have excited much critical interest, Anselmo Suarez y Romero's Francisco is sometimes treated as a nondescript novel of dubious literary stock and suspect antislavery pedigree. Nevertheless, this work occupies a special place in the gallery of these narratives. It was one of the first responses to the request from Richard Madden, the abolitionist Commissioner of the British Mixed Court, for literary compositions by young writers illustrating the Cuban view of slavery. As one of the first full-length literary pieces on the antislavery theme, it began a cycle that was to last for half a century. Suarez, who was born in Havana in 1818, started writing the novel in 1838, and completed it in 1839 at the age of 21. His youth qualified him for special mentoring by the more experienced members of the tertulia or writers' club organized under the auspices of Domingo Del Monte, a patron of the literary arts. Francisco is, in addition, the antislavery novel whose genealogy has been most fully documented. The novel was composed cooperatively, being in pan the product of ongoing exchanges between the author and members of the Del Monte tertulia, who contributed to its production by their commendations and criticisms. Whether to shed light or to cast their shadow on subsequent interpretations of the novel, the letters between members of the writers' circle during the course of its composition have been included as indispensable extensions of the text in its various editions. The edited version of the manuscript, which was included in the antislavery album delivered to Madden, has not been published and seems to have been lost. If the author is to be believed, the unedited version was the one that finally appeared in print in New York some 36 years later in 1880, after the abolition of slavery in Cuba. Neither version was subject, therefore, to the constraints of official censorship; the edited one was destined for Madden, not for public consumption in Cuba, while the original was published under a more liberal political regime. In offering his preferred reading of the work, Suarez's apologetic posture on its style is counterbalanced by his unabashed defence of its compelling moral message: usually laugh at the many clumsy words and phrases and the host of redundancies and tedious repetitions; but when I think of Francisco and Dorotea, victims of a horrible institution, I believe that even the most severe literary judge would have to silence his criticism to join me in weeping for those two wretched slaves1 (41). In a similar fashion, different commentators on the novel have used canonical criteria to make light of its literary value and have helped to divert attention from its discursive dimension.2 Using the insights offered by contemporary literary theories this essay proposes a reading of the unedited version that will broaden and deepen our understanding of the novel by focusing on the subversive effect of various unobtrusive signs included by the author. Postcolonial readings of colonial discourse, Mikhail Bakhtin's theory of the novel, as well as the methods of deconstruction and psychoanalysis are interpretive tools that will be engaged to explore certain unmined areas of this novel. These theoretical tools will help to tease out its multiple threads and, hopefully, help to correct some of the existing misperceptions of aspects of Suarez's composition. At the centre of the novel is the cliched Romantic fable of the ill-fated love between Francisco and Dorotea, two favoured house slaves, which is thwarted by their widowed mistress, Dolores Mendizabal and her son, Ricardo. Dona Dolores not only refuses their pleas for permission to marry, but eventually forbids their relationship. The slaves continue their affair in secret, and this leads to Dorotea's pregnancy, a crime which earns them expulsion from serving in the house. …

Temporal Variations in Water Chemistry at Abandoned Underground Mines Hosted in a Carbonate Environment

Closure of Pb-Zn mines in the Iglesias district (SW Sardinia, Italy) caused the cessation of pumping in 1997, and the consequent flooding of underground workings. Deep saline water mixed with the shallow groundwater as the water table rose, increasing salinity. Stratification caused the saline water at depth to settle over a period of three years. At the beginning of rebound, an increase in dissolved Zn, Cd, Pb, and Hg was observed under near-neutral pH conditions. Following peak concentrations, a marked decrease of Zn, Cd, and Hg, and to a lesser extend Pb, occurred. After 7 years of rebound, the concentrations of these metals are relatively low at most mine sites, although the levels are generally still higher than in unmined areas. Nowadays, the highest release of metals to the aquatic system occurs from the weathering of tailings and mine wastes.

Breeding biology of Henslow's Sparrows on reclaimed coal mine grasslands in Kentucky

Populations of Henslow's Sparrows (Ammodramus henslowii) are declining, and loss of habitat is a likely factor. Coal mine reclamation has created grassland habitat in Kentucky and elsewhere, and information is needed concerning the use of these areas by Henslow's Sparrows. We compared the behavior and ecology of populations on reclaimed sites and non-mined sites in west-central Kentucky during the 2000 and 2001 breeding seasons. Territories were smaller on the reclaimed sites than unmined sites, perhaps due to differences in habitat quality. Insect sweeps revealed more prey biomass on reclaimed sites than unmined sites. Twenty-eight of 48 nests (58%) fledged at least one young, and nesting success was similar on reclaimed and unmined sites. Mean clutch size was 3.75, with no difference between reclaimed and unmined sites. Similarly, the mean number of fledglings per nest was similar on reclaimed and unmined sites. Multivariate analysis revealed differences in the characteristics of vegetation on reclaimed areas and unmined areas. Reclaimed areas had more grass cover and greater vegetation density, probably due to differences in management history (i.e., mowing or burning) and species composition. Our results indicate that the nesting success of Henslow's Sparrows on reclaimed surface mines in Kentucky is comparable to that on unmined areas. As such, the thousand of hectares of reclaimed surface mines in Kentucky and elsewhere could play an important role in stabilizing populations of Henslow's Sparrows.

Can UK coal resources contribute to a gas renaissance?

The predicted shortage of indigenous UK natural gas coincides with the continuing decline of the UK deep coal mining industry. Significant capacity has been lost through mine closures over the last few years as a result of competition from cheaper sources of coal from overseas and changes to the UK energy market. It is unlikely that any new large underground mines will be developed in the UK in the short or medium term. There are, however, still vast untouched coal resources in the UK that represent a significant energy resource. Increased awareness of the potential for clean energy from coal seams, advances in technology and recognition of the environmental benefits has seen a revival of interest in the potential to release some of the energy value of UK coal via alternative, non-mining technologies such as coalbed methane production and underground coal gasification. If successful, these could supplement declining conventional UK natural gas production. The utilization of clean energy from coal seams is supported by the UK Government through its Cleaner Fossil Fuels Programme. There is some activity in this field already. Methane is being drained from most of the remaining deep mines and utilized as fuel for electricity generation or on-site boilers. Drained gas that is not utilized is conventionally vented, but at one mine this gas is now flared to reduce greenhouse gas emissions. Methane is also being produced from abandoned mines, but the present low electricity and gas prices have adversely affected its economics. For the longer-term future, there is potential for virgin coalbed methane production and underground coal gasification. The UK has coalbed methane resources estimated to be in the order of 2.9 × 10 12 m 3 CH 4 . However, the limited exploratory drilling for coalbed methane in unmined areas undertaken to date has not led to commercial production – the major barriers are perceived to be low seam permeability, drilling and completion costs, together with planning and access issues. Initial research suggests there is very large potential for underground coal gasification providing the environmental and perceived safety issues surrounding the application of this technology can be overcome.

English

Water quantity and quality conditions are described for a mine-pool aquifer in a fully flooded complex of underground mines in northern West Virginia. Abandoned mines in the Pittsburgh coal bed are contiguous, and separated by coal barrier pillars ranging from as little as 9 to about 60 meters thick. Barrier pillars are transmissive enough to circulate significant quantities of water between mines, yet they control head distribution and flow direction within the aquifer. The mine-pool acts as a partly confined to confined aquifer, and recharge is approximately balanced by withdrawal of about 5700 Liters/minute, leakage to adjacent mines, and unquantified outflow to unmined areas. Resulting drawdown prevents the mine-pool from discharging directly into overlying streams. A centrally located subgroup of mines within the aquifer currently acts as a ground-water sink, but water levels are slowly increasing in the sink, and in some outflow areas. Mine waters are highly reduced, with circumneutral pH, and variable Fe concentrations from 5 to over 100 mg/L. Total alkalinity averages about 200 mg/L with a mixed Ca-Na-HCO3-SO4 composition in recharge areas. End of flow path waters contain up to 600 mg/L alkalinity, and are Na-SO4 type waters with higher dissolved solids and metals concentrations. The shift from Ca to Na dominated waters is attributed mainly to cation exchange. Potentiometric head is increasing in the aquifer, and mine-pool withdrawal may have to be increased to prevent discharge to the surface. Mine-pool quality remains poor, and has shown slow improvement in 6 years of monitoring.

Prevention, control and/or extinguishment of coal seam fires using cellular grout

Coal fires are difficult and persistent problems throughout the world wherever coal is at or near the surface. Coal fires can be associated with mining activities including underground and surface mine operations, coal stockpiles and coal waste piles, and they can also occur in unmined areas along coal seam outcrops. Environmental safety and health hazards are posed by coal fires in the form of ground surface subsidence, air pollution, forest and brush fires, and destruction of property and surface improvements, in addition to the potential massive loss of energy resources. While many causes exist, the most common source of coal fire ignition is spontaneous combustion as weathered, or broken/pulverized coal oxidizes and the temperature rises to the ignition point. This process can occur before any mining in the case of outcrop fires, or anytime during and after the mining cycle. The magnitude of coal fire problems varies worldwide depending on reserves available, extent of mining, population, political/economic situations, and a host of other influencing factors. Mining and environmental regulations imposed in the United States have heightened awareness regarding coal fire problems and resulted in efforts to control the most problematic existing fires and extinguish small fires before they escalate. Coal fires in other major coal-bearing countries, such as China and India, pose a significantly greater problem in terms of worldwide impact. Figures for China vary dramatically but estimates indicate that as much as 100–200 million tons of coal reserves are consumed annually as a result of coal fires. Similar estimates for the Jharia Coal Field in India indicate that about 40 million tons of coal reserves were burned during the 1990s. These data point to a significant source of global pollution, in addition to substantial economic losses. Goodson & Associates, Inc. (G & AI), a Lakewood, CO engineering firm, has developed a technology utilizing cellular (foam containing) grout to mitigate coal fires from the perspectives of prevention, control and extinguishment. The variable combination of portland cement, waste fly ash, aggregates and special foams create a highly flowable, high-heat resistant grout that is used to simultaneously address each of the three necessary fire elements: fuel, oxygen and heat. Coal fire prevention can be achieved by spraying the material on the exposed surface of coal seams following completion of strip mining. Control is enabled by grout injection into cracks, vents and cut-off trenches to stall or prevent continued growth. Extinguishment can be accomplished by grout injection directly into the fire zone, air intakes and exhausts. The benefits of using this technology are numerous. Cellular grout injection is safer at lower cost than conventional techniques such as complete excavation, while causing less environmental disruption and providing for quicker applications. The use of large quantities of fly ash in the process is economically and environmentally sound, by providing for disposal of a waste material while addressing the worldwide problem of coal fires.

Ground-Water Flow and Quality in A Fully Flooded Underground Complex

Water quantity and quality conditions are described for a mine-pool aquifer in a fully flooded complex of underground mines in northern West Virginia. Abandoned mines in the Pittsburgh coal bed are contiguous, and separated by coal barrier pillars ranging from as little as 9 to about 60 meters thick. Barrier pillars are transmissive enough to circulate significant quantities of water between mines, yet they control head distribution and flow direction within the aquifer. The mine-pool acts as a partly confined to confined aquifer, and recharge is approximately balanced by withdrawal of about 5700 Liters/minute, leakage to adjacent mines, and unquantified outflow to unmined areas. Resulting drawdown prevents the mine-pool from discharging directly into overlying streams. A centrally located subgroup of mines within the aquifer currently acts as a ground-water sink, but water levels are slowly increasing in the sink, and in some outflow areas. Mine waters are highly reduced, with circumneutral pH, and variable Fe concentrations from 5 to over 100 mg/L. Total alkalinity averages about 200 mg/L with a mixed Ca-Na-HCO3-SO4 composition in recharge areas. End of flow path waters contain up to 600 mg/L alkalinity, and are Na-SO4 type waters with higher dissolved solids and metals concentrations. The shift from Ca to Na dominated waters is attributed mainly to cation exchange. Potentiometric head is increasing in the aquifer, and mine-pool withdrawal may have to be increased to prevent discharge to the surface. Mine-pool quality remains poor, and has shown slow improvement in 6 years of monitoring.

Impacts of surface mine valley fills on headwater floods in eastern Kentucky

The potential impacts of valley fills associated with mountaintop removal/valley fill (MTR/VF) coal mining on downstream flooding in the coalfields of eastern Kentucky and adjacent states are a subject of public debate and scientific uncertainty. This study explored two aspects of this issue. First, hydrologic indices of relative runoff production and surface and subsurface flow detention were applied to conditions typical of headwater and low-order drainage basins in eastern Kentucky. Results show that there is a clear risk of increased flooding (greater runoff production and less surface flow detention) following MTR/VF operations, and suggest that, on balance, valley fills are more likely to increase rather than decrease flood potential. However, there is a wide range of outcomes, qualitatively and quantitatively. Flood risks can be increased or decreased, and the degree of either may vary markedly. The effects of MTR/VF mining on downstream peak flows are highly contingent on local pre- and post-mining conditions, and it would be unwise to apply generalizations to specific sites. Second, the occurrence of flash floods downstream of MTR/VF operations when nearby unmined areas did not flood or had less severe floods has frequently been explained (without supporting data) in terms of locally greater precipitation. The likelihood of such short-range variability of storm precipitation is evaluated by applying the state probability function to NEXRAD radar estimates of precipitation for two 2001 storms which produced flash floods in eastern Kentucky. The spatial structure of the storm precipitation indicates that at the scale of the analysis (pixel size of approximately 2 km) large local variations in storm precipitation are unlikely—that is, the probability of nearby hollows or low-order drainage basins receiving substantially different storm precipitation totals is low.

Impact Of Gold Mining On Vegetation And Soil In Southwestern NIGERIA

This paper describes the current status of vegetation and determines the trace element concentration, of plant species and soil in the Ilesa goldfields of Southwestern Nigeria. The results show that there is a drastic reduction in the vegetal cover in the area as a result of mining activities. There is also an appreciable level of contamination of soil and plant species of the mined sites compared with unmined areas. For instance, the Pb content in cassava and oil palm grown on the mined sites are much higher than the FAO/WHO guideline. The results of this study underscore the need for close monitoring of mining operations in Southwestern Nigeria.

Is There a Characteristic Flora of Appalachian pre-SMCRA Surface Mines?

Within a landscape, specific physical habitats (shale barrens, limestone glades, acid bogs, etc.) are often characterized by their floras – the collection of plant species or taxa that inhabit them. Composition of some floras can be unique because their environments have characteristics that allow colonization by some taxa and select against colonization by others. A significant proportion of Appalachia was mined with limited reclamation before the Surface Mine Control and Reclamation Act of 1977 (SMCRA). Successional processes have, over time, enriched the plant communities on these mines to the point that their taxonomic richness is comparable to similar unmined areas. But are the floras of these mines distinctive unto themselves?

Flora of the Fonde Surface Mine Demonstration Area, Bell County, Kentucky

The pre-SMCRA, 7.3-ha Fonde Surface Mine Demonstration Area supported a vascular plant flora of 299 taxa after 24 years of succession. Relative richness of this mine was 88 percent of that to be expected in an unmined area of this size in the Mixed and Western Mesophytic Forest Regions, and this relative richness is similar to that found in other completely inventoried pre-SMCRA mined areas in Appalachia. One species, Scirpus fluviatilis, is on the Kentucky list of threatened plant species. Native taxa comprised 82.2 percent of the flora. Out of 31 taxa that were planted for reclamation and research purposes, 26 still remained. The planted herbaceous taxa have, for the most part, yielded to native taxa. Abundances of 73 percent of the taxa were rated as infrequent or rare. This abundance distribution is similar to that obtained when lognormally distributed species are assigned to abundance categories. Other studies of rec laimed mined lands using sampling methods returned lower relative richness and located no threatened or endangered species. Given the inherent advantages and disadvantages of inventories and sampling studies, we suggest that a combination of both methods is most desirable for future studies of succession and biodiversity on reclaimed surface mines and other areas.

Management of topsoil for geo-environmental reclamation of coal mining areas

Topsoil is an essential component for land reclamation in mining areas. It is seriously damaged if it is not mined out separately without being contaminated, eroded and protected. Systematic handling and storage practices can protect topsoil while in storage and after it has been redistributed onto the regraded area. Impact of coal mining on topsoil quality in Indian context has been described. Systematic removal of topsoil, its storage practice, geometry of topsoil heap are discussed in this study. Removed topsoil should be reclaimed technically and its shelf-life period should be ascertained. To assess the shelf-life period, an investigation was conducted in a large opencast coal project. Soil dumps of different age classes in the area were identified and analyzed critically to evaluate the deterioration of soil quality with respect to time, and compared with those of unmined areas. Changes in soil quality showed a continuous decrease every year and ultimately became biologically sterile. Biological reclamation is essential if the soil is to be stored beyond the shelf-life period. Preservation of stockpiled topsoil, its redistribution on the regraded areas, nutrients and amendments to be added, are discussed briefly in this study.

Water-quality trends for a stream draining the Southern Anthracite Field, Pennsylvania

Stream flow, chemical and biological data for the northern part of Swatara Creek, which drains a 112 km 2 area in the Southern Anthracite Field of eastern Pennsylvania, indicate progressive improvement in water quality since 1959, after which most mines in the watershed had been flooded. Drainage from the flooded mines contributes substantially to base flow in Swatara Creek. Beginning in 1995, a variety of treatment systems and surface reclamation were implemented at some of the abandoned mines. At Ravine, Pa., immediately downstream of the mined area, median SO 4 concentration declined from about 150 mg l −1 in 1959 to 75 mg l −1 in 1999 while pH increased from acidic to near-neutral values (medians: c. pH 4 before 1975; c. pH 6 after 1975). Fish populations rebounded from non-existent during 1959–1990 to 21 species identified in 1999. Nevertheless, recent monitoring indicates (1) episodic acidification and elevated concentrations and transport of Fe, Al, Mn, and trace metals during storm flow; (2) elevated concentrations of Fe, Mn, Co, Cu, Pb, Ni, and Zn in streambed sediments relative to unmined areas and to toxicity guidelines for aquatic invertebrates and fish; and (3) elevated concentrations of metals in fish tissue, notably Zn. The metals are ubiquitous in the fine fraction (<0.063 mm) of bed sediment in mining-affected tributaries and the main stem of Swatara Creek. As a result of scour and transport of streambed deposits, concentrations of suspended solids and total metals in the water column are correlated, and those for storm flow typically exceed base flow. Nevertheless, the metals concentrations are poorly correlated with stream flow because concentrations of suspended solids and total metals typically peak prior to peak stream stage. In contrast, SO 4 , specific conductance and pH are inversely correlated with stream flow as a result of dilution of poorly buffered stream water with weakly acidic storm runoff derived mainly from low-pH rainfall. Declines in pH to values approaching 5.0 during storm flow events or declines in redox potential during burial of sediment could result in the remobilization of metals associated with suspended solids and streambed deposits.

Rehabilitation of Gypsum-Mined Lands in the Indian Desert

The economic importance of mining in the Indian Desert is second only to agriculture. Land disturbed by mining, however, has only recently been the focus of rehabilitation efforts. This research assesses the success of rehabilitation plans used to revegetate gypsum mine spoils within the environmental constraints of the north west Indian hot-desert ecosystem. The rehabilitation plan first examined both mined and unmined areas and established assessments of existing vegetative cover and the quality of native soils and mine spoils. Tests were made on the effect of the use, and conservation, of available water through rainwater harvesting, amendment application (for physical and chemical spoil modification), plant establishment protocols, and the selection of appropriate germplasm. Our results show that the resulting vegetative cover is capable of perpetuating itself under natural conditions while concurrently meeting the needs of farmers. Although the mine spoils are defi cient in organic matter and phosphorus, they possess adequate amounts of all other nutrients. Total boron concentrations (g 5.0 mg kg-1) in both the topsoil and mine spoil indicate potentially phytotoxic conditions. Electrical conductance of mine spoil is 6-10 times higher than for topsoil with a neaR-neutral pH. Populations of spoil fungi, Azotobactor, and nitrifying bacteria are low. The soil moisture storage in rainwater harvesting plots increased by 8 % over the control and 48 % over the unmined area. As a result of rehabilitation efforts, mine spoils show a steady buildup in organic carbon, and P and K due to the decomposition of farmyard manure and the contribution of nitrogen fixation by the established leguminous plant species. The rehabilitation protocol used at the site appears to have been successful. Following revegetation of the area with a mixture of trees, shrubs, and grasses, native unplanted species have become established. Species diversity, measured in terms of species richness, increased after one year and then gradually declined over time; the decline was the result of the loss of annual species. The study not only develops methods of gypsum mine land rehabilitation but also helps in understanding pro cesses of rehabilitation success in arid regions and emphasizes the importance of long-term monitoring of rehabilitation success.

Rehabilitation of Gypsum-Mined Lands in the Indian Desert

The economic importance of mining in the Indian Desert is second only to agriculture. Land disturbed by mining, however, has only recently been the focus of rehabilitation efforts. This research assesses the success of rehabilitation plans used to revegetate gypsum mine spoils within the environmental constraints of the north west Indian hot-desert ecosystem. The rehabilitation plan first examined both mined and unmined areas and established assessments of existing vegetative cover and the quality of native soils and mine spoils. Tests were made on the effect of the use, and conservation, of available water through rainwater harvesting, amendment application (for physical and chemical spoil modification), plant establishment protocols, and the selection of appropriate germplasm. Our results show that the resulting vegetative cover is capable of perpetuating itself under natural conditions while concurrently meeting the needs of farmers. Although the mine spoils are defi cient in organic matter and phosphorus, they possess adequate amounts of all other nutrients. Total boron concentrations (g 5.0 mg kg-1) in both the topsoil and mine spoil indicate potentially phytotoxic conditions. Electrical conductance of mine spoil is 6-10 times higher than for topsoil with a neaR-neutral pH. Populations of spoil fungi, Azotobactor, and nitrifying bacteria are low. The soil moisture storage in rainwater harvesting plots increased by 8 % over the control and 48 % over the unmined area. As a result of rehabilitation efforts, mine spoils show a steady buildup in organic carbon, and P and K due to the decomposition of farmyard manure and the contribution of nitrogen fixation by the established leguminous plant species. The rehabilitation protocol used at the site appears to have been successful. Following revegetation of the area with a mixture of trees, shrubs, and grasses, native unplanted species have become established. Species diversity, measured in terms of species richness, increased after one year and then gradually declined over time; the decline was the result of the loss of annual species. The study not only develops methods of gypsum mine land rehabilitation but also helps in understanding pro cesses of rehabilitation success in arid regions and emphasizes the importance of long-term monitoring of rehabilitation success.

Aftershocks of an explosively induced mine collapse at White Pine, Michigan

AbstractWe recorded an explosively induced, 320-m-deep mine collapse and subsequent aftershocks at White Pine, Michigan, using an array of 12 seismic stations, sited within 1 km of surface ground zero. The collapse, which followed the rubblizing of a 2 × 104 m2 panel of a room-and-pillar copper mine, was induced to facilitate leaching operations. The explosions produced little seismic energy; however, fracturing and collapse stages produced large signals that were observed at distances up to 900 km, yielding a magnitude (mbLg) of 2.8. Previous work showed the initial collapse to be an expanding seismic source, interpreted as an opening tensile crack, opposite to the implosional character most often observed for natural mine collapses (Yang et al., 1998). We counted over 4000 aftershocks; their occurrence rate followed the modified Omori law: rate = 560 (time − 0.01)−1.3, with time in hours. Based on P-wave polarities, we identified events of shear-slip, implosional, and tensile character in the aftershock sequence. For shear-slip events, we found stress drops of 1 bar or less, seismic moments of 1015−1017 dyne cm, (Mw−0.8−0.5) and source radii of 10-50 m. Corner frequencies for implosional events were relatively low, an indication that the collapsed cavity played a role in the source process. This caused implosional events to separate from other events in source parameter plots, providing a technique for classifying events of unknown type. We obtained locations of 135 aftershocks using P- and S-wave data. The aftershock zone was less than 100-m thick, situated just above and along the western, mined edge of the collapsed mine panel. Implosional events occurred at the bottom of the active volume, while shear-slip events were distributed throughout. Shear-slip focal mechanisms indicated thrusting along north-striking planes, consistent with the high, eastwest regional compressive stress, coupled with a local decrease in vertical stress. The inferred deficit of vertical stress above the western panel edge following collapse indicated that overburden load shifted preferentially to the surrounding, unmined areas, consistent with lower-than-predicted stresses measured in the first row of intact pillars.

99/00268 Kinetic study of the water gas shift reaction and its role in the conversion of methane to syngas over a Pt/MgO catalyst

Coal fires are difficult and persistent problems throughout the world wherever coal is at or near the surface. Coal fires can be associated with mining activities including underground and surface mine operations, coal stockpiles and coal waste piles, and they can also occur in unmined areas along coal seam outcrops.Environmental safety and health hazards are posed by coal fires in the form of ground surface subsidence, air pollution, forest and brush fires, and destruction of property and surface improvements, in addition to the potential massive loss of energy resources. While many causes exist, the most common source of coal fire ignition is spontaneous combustion as weathered, or broken/pulverized coal oxidizes and the temperature rises to the ignition point. This process can occur before any mining in the case of outcrop fires, or anytime during and after the mining cycle.The magnitude of coal fire problems varies worldwide depending on reserves available, extent of mining, population, political/economic situations, and a host of other influencing factors. Mining and environmental regulations imposed in the United States have heightened awareness regarding coal fire problems and resulted in efforts to control the most problematic existing fires and extinguish small fires before they escalate. Coal fires in other major coal-bearing countries, such as China and India, pose a significantly greater problem in terms of worldwide impact. Figures for China vary dramatically but estimates indicate that as much as 100–200 million tons of coal reserves are consumed annually as a result of coal fires. Similar estimates for the Jharia Coal Field in India indicate that about 40 million tons of coal reserves were burned during the 1990s. These data point to a significant source of global pollution, in addition to substantial economic losses.Goodson & Associates, Inc. (G & AI), a Lakewood, CO engineering firm, has developed a technology utilizing cellular (foam containing) grout to mitigate coal fires from the perspectives of prevention, control and extinguishment. The variable combination of portland cement, waste fly ash, aggregates and special foams create a highly flowable, high-heat resistant grout that is used to simultaneously address each of the three necessary fire elements: fuel, oxygen and heat.Coal fire prevention can be achieved by spraying the material on the exposed surface of coal seams following completion of strip mining. Control is enabled by grout injection into cracks, vents and cut-off trenches to stall or prevent continued growth. Extinguishment can be accomplished by grout injection directly into the fire zone, air intakes and exhausts.The benefits of using this technology are numerous. Cellular grout injection is safer at lower cost than conventional techniques such as complete excavation, while causing less environmental disruption and providing for quicker applications. The use of large quantities of fly ash in the process is economically and environmentally sound, by providing for disposal of a waste material while addressing the worldwide problem of coal fires.

Geotechnical classification of deep and ultra-deep Witwatersrand mining areas, South Africa

As depth of mining increases, so the production costs of the aurifereous Witwatersrand deposits are continuously increasing, with some mines already mining at depths exceeding 3500 m. Health and safety aspects are, simultaneously, gaining in importance. Therefore, in order to mine deep orebodies in existing mines, as well as to develop new mining ventures safely and efficiently, novel approaches, including mining strategies, layouts and support systems have to be adopted. Geological features largely control the deformation mechanisms associated with Witwatersrand orebodies. These features are grouped into two major categories: primary and secondary features. Both impact on the rockmass behaviour associated with the excavations, and contribute to the definition of geotechnical areas. Primary geological features are defined by the various rock types, orebody geometry, and the frequency and mineralogical characteristics of sedimentary structures (e.g. various kinds of bedding planes and lithological boundaries). The primary features also control rock engineering properties, closure rates, attitude and frequency of mining-induced stress fracturing, and planes may be reactivated during seismic events. Secondary geological features are faults, dykes and veins/joints, and associated metamorphism. These cause stability problems and are often associated with seismic events. Compositional and textural characteristics of these features, and their controls on the rockmass behaviour, are ill-defined. Primary and secondary geological characteristics also play an important role in identifying the appropriate mining strategy, layout and support. Geological features can be predicted into deep unmined areas, and therefore contribute to the safest and most efficient extraction of the orebody. Witwatersrand orebodies are mined in complex geological environments, with the rockmass behaviour differing from one orebody to the other. This is approached by employing a new methodology that attempts to quantify the problems encountered when mining the major Witwatersrand orebodies.

Deep‐sea Environmental Disturbance and Recovery Potential

AbstractMining the abyssal seafloor for manganese nodules will destroy the hard substrate and it will severely disturb the seabed and the benthic soft substrate community. Recolonization will occur from unmined areas. Reestablishment of a community similar to that originally present is, however, not possible, since the nodules will be removed and epigrowth on hard substrates is thereby precluded. Small scale experiments using azoic sediment in trays exposed to ambient deep‐sea conditions, may not be appropriate models for large scale recolonization processes.Results of such experiments and general knowledge of deep‐sea ecology suggest that decades may be required for reestablishment of a balanced community.With respect to evaluation of some ecological consequences of mining an ongoing large scale experiment, termed DISCOL (DIS‐turbance and re‐COL‐onization) is shortly described as a new approach in deep‐sea risk assessment.

Natural Revegetation of an Unreclaimed Lignite Surface Mine in East-Central Texas

Evaluating plants and soils on unreclaimed surface mines helps land managers un- derstand the effects of minesoil properties on plant growth and community development and may aid in the development of current reclamation plans. Eight unreclaimed surface mined sites in east-central Texas, ranging in age from 3 months to 50 years, were sampled to evaluate vegetation and minesoil changes over time and for comparison to an adjacent unmined area. Three- and 6-month-old unre- claimed areas had about 1% plant cover composed of pioneer grass and forb genera, including Di- chanthelium, Aster, Chenopodium, and Polygonum. Herbaceous plant cover increased from 12% on the 5-year-old site to a peak of 25% on the 20-year-old site. Dominant genera on 10- to 20-year-old sites were Andropogon, Bothriochloa, Cynodon, Dichanthelium, Paspalum, Aster, and Rumex. Woody species established as early as 5 years after mining (predominantly Baccharis salicina T. et G.), and canopy cover reached 14 and 35% on the 20- and 30-year-old sites, respectively. On the 50-year-old site, 17 woody species formed a multilayered vegetation structure with > 100% cover. Bulk density of minesoils in the surface 12 cm declined with time from 1.30 to <1.00 Mg/m3 as vegetation and litter increased. Undisturbed soils had an average pH of 5.9. Minesoil pH decreased from 6.9 on 3- and 6-month- old sites to 3.8 on 5- to 30-year-old sites (due to pyrite oxidation) and increased to 6.8 on the 50- year-old site. Several grass and forb species found on acidic minesoils in this study may be good candidates for low input revegetation programs for other postmining land uses.