Open Cut Coal Mine Research Articles

Characterization of particulate emissions from Australian open-cut coal mines: Toward improved emission estimates

ABSTRACTGiven the significance of mining as a source of particulates, accurate characterization of emissions is important for the development of appropriate emission estimation techniques for use in modeling predictions and to inform regulatory decisions. The currently available emission estimation methods for Australian open-cut coal mines relate primarily to total suspended particulates and PM10 (particulate matter with an aerodynamic diameter <10 μm), and limited data are available relating to the PM2.5 (<2.5 μm) size fraction. To provide an initial analysis of the appropriateness of the currently available emission estimation techniques, this paper presents results of sampling completed at three open-cut coal mines in Australia. The monitoring data demonstrate that the particulate size fraction varies for different mining activities, and that the region in which the mine is located influences the characteristics of the particulates emitted to the atmosphere. The proportion of fine particulates in the sample increased with distance from the source, with the coarse fraction being a more significant proportion of total suspended particulates close to the source of emissions. In terms of particulate composition, the results demonstrate that the particulate emissions are predominantly sourced from naturally occurring geological material, and coal comprises less than 13% of the overall emissions. The size fractionation exhibited by the sampling data sets is similar to that adopted in current Australian emission estimation methods but differs from the size fractionation presented in the U.S. Environmental Protection Agency methodology. Development of region-specific emission estimation techniques for PM10 and PM2.5 from open-cut coal mines is necessary to allow accurate prediction of particulate emissions to inform regulatory decisions and for use in modeling predictions.Implications: Development of region-specific emission estimation techniques for PM10 and PM2.5 from open-cut coal mines is necessary to allow accurate prediction of particulate emissions to inform regulatory decisions and for use in modeling predictions. Comprehensive air quality monitoring was undertaken, and corresponding recommendations were provided.

MINErosion 3: Using measurements on a tilting flume-rainfall simulator facility to predict erosion rates from post-mining landscapes in Central Queensland, Australia.

Open-cut coal mining in Queensland results in the formation of extensive saline overburden spoil-piles with steep slopes at the angle of repose (approximately 75% or 37o). These spoil-piles are generally found in multiple rows, several kilometers in length and heights of up to 50 or 60 m above the original landscape. They are highly dispersive and erodible. Legislation demands that these spoil piles be rehabilitated to minimize on-site and off-site discharges of sediment and salt into the surrounding environment. To achieve this, the steep slopes must be reduced, stabilized against erosion, covered with topsoil and re-vegetated. Key design criteria (slope gradient, slope length and vegetation cover) are required for the construction of post-mining landscapes that will result in acceptable erosion rates.A novel user-friendly hillslope computer model MINErosion 3.4 was developed that can accurately predict potential erosion rates from field scale hillslopes using parameters measured with a 3m laboratory tilting flume-rainfall simulator or using routinely measured soil physical and chemical properties. This model links MINErosion 2 with a novel consolidation and above ground vegetation cover factors, to the RUSLE and MUSLE equations to predict the mean annual and storm event erosion rates. The RUSLE-based prediction of the mean annual erosion rates allow minesites to derive the key design criteria of slope length, slope gradient and vegetation cover that would lead to acceptable erosion rates. The MUSLE-based prediction of storm event erosion rates will be useful as input into risk analysis of potential damage from erosion.MINErosion 3.4 was validated against erosion measured on 20 m field erosion plots established on post-mining landscapes at the Oakey Creek and Curragh coalmines, as well as on 120 and 70 m erosion plots on postmining landscapes at Kidston Gold Mine.

Lived experiences of environmental change: Solastalgia, power and place

The concept of solastagia has been developed by environmental philosopher Albrecht to understand the psychological trauma, also referred to as place-based distress, experienced because of environmental change. In this article, we explore ways to further this concept. The article draws on ethnographic fieldwork in a village in the mid-western region of New South Wales (NSW), Australia, which is surrounded by three large open-cut coal mines. Over the past decade, the mines, in particular the Peabody-owned Wilpinjong mine closest to the village, have had a significant impact on biophysical, social and temporal landscapes in the area. We argue that whilst solastalgia may help explore the relationship between the environmental and human distress triggered in these circumstances, the sense of displacement and loss that emerge are entangled with questions of power and dispossession beyond the biophysical realm. Underpinned by a phenomenological framework of analysis, we contend that place-based distress should be understood as an ontological trauma, as the fabrics of place, belonging and the social relations embedded within disrupt the ongoing sense of being associated with home. These include the means to not only link to the past, but also to imagine the future.

Recovery of reptile, amphibian and mammal assemblages in Australian post-mining landscapes – open cut coal mining

Recovery of reptile, amphibian and mammal assemblages in Australian post-mining landscapes – open cut coal mining

Groundwater impact of open cut coal mine and an assessment methodology: A case study in NSW

Large scale open cut coal mining operations have significant impacts to groundwater in surrounding areas in both active and post-mining phases. The prediction of water inflows into a surface mine excavation is one of the many components involved in mine design phase. Groundwater performance also reacts to mining activities from the operational, economic and safety implications perspective. Under NSW planning legislation, as part of the comprehensive risk assessment, a groundwater impact assessment has to be conducted for a coal project to predict and mitigate the impacts in consideration of the government requirements. In this paper, the groundwater assessment modelling of mine pits was discussed in predicting of groundwater inflows and reviewing analytical and numerical approaches. A methodology of groundwater impact assessment for an open cut mine in NSW with a three-dimensional groundwater flow model Modflow Surfact demonstrated its functions in simulating the project’s impacts on the groundwater regime. The key findings with mitigations are discussed and recommended in the paper to reduce impacts on groundwater and fulfil regulation requirements in NSW.

Fire behaviour on engineered landforms stabilised with high biomass buffel grass

Rehabilitated lands created by open-cut coal mines are generally protected by land managers from fire and grazing disturbances. This practice is employed to reduce negative impacts, such as erosion, on the developing ecosystems. However, fire exclusion over long periods inadvertently contributes to increased fire risk on rehabilitated landforms, particularly when high biomass, mono-dominant grasses form a major component of these new ecosystems. In May 2015, an experimental fire burnt 117ha of rehabilitation at a coal mine site in the Bowen Basin, Australia. Standing grass fuel loads, dominated by buffel grass (Cenchrus ciliaris L.), were up to 9.3t/ha in grassland areas and 5.3t/ha in areas of open woodland. Average litter fuel loads were 2.4 and 3.6t/ha for grassland and open woodland, respectively. Calculated fire intensity was higher in grassland (4612±502kWm−1) than open woodland areas (1977±804kWm−1) indicating that rehabilitated landforms dominated by buffel grass may represent a higher fire risk to mine sites and regional areas in the Bowen Basin when compared to the original vegetation. Fire behaviour reflected the varying underlying terrain, fuel loads and surface soil or overburden conditions. Further research is recommended to investigate fire behaviour in buffel grasslands across a range of fuel load and curing conditions, with the aim to develop an invasive grass fire spread model that can be used inform both landscape reconstruction prescriptions for ecological engineers and more broadly in managing the fire risk across landscapes dominated by these vegetation types.

Study on Soil Spread at Rehabilitation Area for Promotion of Plant Growth in Open Cut Coal Mine in Kalimantan Area in Indonesia

Study on Soil Spread at Rehabilitation Area for Promotion of Plant Growth in Open Cut Coal Mine in Kalimantan Area in Indonesia

A Framework for Geotechnical Hazard Analysis in Highwall Mining Entries

Highwall mining involves driving a series of parallel entries with web pillars in between. These entries are driven by using a continuous miner with attached conveying system to extract locked up coal behind the highwall slope when the open cut coal mine reaches its ultimate limit. These entries are driven unmanned, unventilated and unsupported. Therefore, a detailed knowledge of structural features ahead of operations is essential in assessing the stability of these entries. Highwall mining operations can greatly benefit from accurate structural mapping of rock mass defects. The stability of these entries can be suitably assessed for any major roof failure by adopting discrete fracture network based structural modelling to characterize and delineate the regions of possible major roof failures to prevent damage to the conveyor and burial of the expensive continuous miner. In this paper, a generalized framework is described based on photogrammetric survey, digital mapping and discrete fracture network based structural modelling to characterise such failures for an Indian highwall mining operation. A sensitivity analysis is undertaken to demonstrate the significance of structure persistence in the geotechnical assessment. Such analysis would provide more insight into designing highwall mining layouts and in predicting possible impending highwall failures, and indirectly facilitates reducing machine downtime for better management of highwall mining operations.

Characteristics of an open-cut coal mine fire pollution event

On 9 February 2014, embers from a nearby grass/shrub fire spotted into an unused part of the Hazelwood open-cut brown coal mine located in the Latrobe Valley of Victoria, Australia and started a fire that spread rapidly and extensively throughout the mine under strong south-westerly winds and burned over a period of 45 days. The close proximity of the town to the coal mine and the low buoyancy of the smoke plume led to the accumulation of dense smoke levels in the township of Morwell (population of 14,000) particularly under south-westerly winds. A maximum daily PM2.5 concentration of 731 μg m−3 and 8-h CO concentration of 33 ppm were measured at Morwell South, the closest residential area located approximately 500 m from the mine. These concentrations were significantly higher than national air quality standards. Air quality monitoring undertaken in the Latrobe Valley showed that smoke from the Hazelwood mine fire affected a wide area, with particle air quality standards also exceeded in Traralgon (population of 25,000) located approximately 13 km from the mine. Pollutant levels were significantly elevated in February, decreased in March once the fire abated and then returned to background levels once the fire was declared safe at the end of March.While the smoke extent was of a similar order of magnitude to other major air pollution events worldwide, a closer look at emissions ratios showed that the open combustion of lignite brown coal in the Hazelwood mine was different to open combustion of biomass, including peat. It suggested that the dominant combustion process was char combustion. While particle and carbon monoxide monitoring started approximately 4 days after the fire commenced when smoke levels were very high, targeted monitoring of air toxics only began on 26 February (17 days after the fire) when smoke levels had subsided. Limited research on emission factors from open-cut coal mine fires make it difficult to assess the likely concentrations of air toxics emitted during the initial more intense period of the fire.

Spatial assessment of open cut coal mining progressive rehabilitation to support the monitoring of rehabilitation liabilities

Worldwide coal mining has expanded over the past few decades, though growth has recently slowed due to reduced demand, partly due to concerns around CO2 emissions and climate change impacts. Coal mining is also a significant driver of land disturbance in regions where economic coal seams and coal mining methods are applied, in particular open cut extraction. To address these impacts, mined landscapes are rehabilitated with the aim of making them safe, stable, non-polluting and self-sustainable to an agreed post-mining land use such as agriculture or conservation. Progressive rehabilitation is often conducted to keep the footprint of disturbance to a minimum and to ensure that ecological and/or agricultural land use production is restored as soon as possible in preference to waiting until after mine closure. Environmental regulators require methods for tracking the performance of mining companies engaging in progressive rehabilitation to evaluate the success or otherwise of their regulatory frameworks and to ensure companies meet the requirements of their environmental authorities or mining licenses.In this study, we describe a spatial method for assessing mine disturbance and rehabilitation regionally and analyse our results in terms of rehabilitation liability. We first developed a land cover classification framework for mapping mining impacts and rehabilitation that categorises land cover using a mining land cover disturbance typology. We then used the Fitzroy Basin in Australia as a case study, utilising the land cover classification scheme to map 37 open cut-coal mines, using manual interpretation of remote sensing data. By comparing the percentage area of rehabilitation with the total mine area we assessed the variability in progressive rehabilitation for the 37 mines. For example, older mines which have a history of progressive rehabilitation should have large areas and a high proportion of area rehabilitated. Finally, we calculated a range of regional rehabilitation liabilities by applying two publically available rehabilitation cost-calculators to the land cover data. We calculated the rehabilitation liability as ranging from $2.7 to $5.5 billion Australian dollars. The lower and upper bounds of the estimate reflect the uncertainty associated with the range of land use types and potential rehabilitation methods, from simple to more complex rehabilitation methods. We conclude by discussing how the methods could be used to support effective decision making by government agencies regulating and monitoring mining activities.

Rising floodwaters: mapping impacts and perceptions of flooding in Indonesian Borneo

The roles of forest and wetland ecosystems in regulating flooding have drawn increasing attention in the contexts of climate change adaptation and disaster risk reduction. However, data on floods are scarce in many of the countries where people are most exposed and vulnerable to their impacts. Here, our separate analyses of village interview surveys (364 villages) and news archives (16 sources) show that floods have major impacts on lives and livelihoods in Indonesian Borneo, and flooding risks are associated with features of the local climate and landscape, particularly land uses that have seen rapid expansions over the past 30 years. In contrast with government assessments, we find that flooding is far more widespread, and that frequent, local, events can have large cumulative impacts. Over three years, local news agencies reported floods that affected 868 settlements, 966 times (including 89 in urban areas), inundated at least 197 000 houses, and displaced more than 776 000 people, possibly as many as 1.5 million (i.e. 5%–10% of the total population). Spatial analyses based on surveys in 364 villages show that flood frequency is associated with land use in catchment areas, including forest cover and condition, and the area of wetlands, mines (open-cut coal or gold mines), and oil palm. The probability that floods have become more frequent over the past 30 years was higher for villages closer to mines, and in watersheds with more extensive oil palm, but lower in watersheds with greater cover of selectively-logged or intact forests. We demonstrate that in data-poor regions, multiple sources of information can be integrated to gain insights into the hydrological services provided by forest and wetland ecosystems, and motivate more comprehensive assessment of flooding risks and options for ecosystem-based adaptation.

Energy from the foodbowl: Associated land-use conflicts, risks and wicked problems

This article reports on a study of an agricultural region in southeast Queensland, Australia that is undergoing rapid change with development of an extensive coal seam gas industry and some large open cut coal mines. The region has become a locus of land use conflict between various industries: farming, grazing, mining and gas extraction. The effects of these multiple industries on each other, on environmental assets, infrastructure and economic and social systems entail many risks. Infrastructure shortfalls, a two-speed economy, widening social divisions, threatened livelihoods and stress in the face of rapid and far-reaching change associated with a new industry are evident in the words of those experiencing the impacts that provide the data reported in the paper. These problems are shown to be characterised by connectedness, complexity, uncertainty, disputed science, conflict, multiple stakeholders and an associated multiplicity of perspectives and values. The problem-solving and management strategies being adopted are unlikely to satisfactorily resolve the ‘wicked’ problems associated with this resources boom because they tackle aspects of the problem in a fragmented way, rely on inconclusive ‘science’, cannot readily incorporate hard to quantify aspects, values and subjective considerations, involve a restricted group of key decision-makers, and are dependent on formal rules and planning. The article proposes characteristics of alternative mechanisms involving adaptive risk management and multi-stakeholder participation. However the authors also caution that most of the barriers identified are not easily overcome.

Comparative sensitivity of aquatic invertebrate and vertebrate species to wastewater from an operational coal mine in central Queensland, Australia

Coal excavation and refinement processes generate substantial volumes of contaminated effluent that may be detrimental to aquatic ecosystems. As such, understanding the impacts of coal mine water releases on aquatic animals and ecosystems is essential for effectively managing and protecting neighboring environments. Such information will ultimately be applied towards developing ongoing monitoring strategies that are protective of native wildlife. Despite intensive mining operations in Australia, few studies have documented toxicity associated with coal mine wastewater (CMW) on native species. To address existing knowledge gaps, we investigated acute toxicity (48–96h) using eight native invertebrate species and sub-chronic effects (2 week) using three vertebrate species following exposure to wastewater from two dams (CMW1 and CMW2) located at an open-cut coal mine licensed to discharge into the Fitzroy catchment (Queensland, Australia). Wastewater from these sites is characterized by elevated conductivity, pH, sulfates as well as relatively high total and dissolved metal(loid)s (including As, Al, B, Cu, Mn, Ni, Se and Zn). Acute exposures revealed cladocerans (Daphnia carinata) and planarians (Dugesia sp.) to be the most sensitive species, exhibiting significant mortality after 48 and 96h exposure to CMW2, respectively. Neither wastewater was found to elicit acute toxicity in vertebrates, but a range of sub-lethal morphological effects were observed following the sub-chronic exposures. The overall response pattern was characterized by decreased condition factor and hepatosomatic index in the fish Hypseleotris compressa and Pseudomugil signifier, and in Limnodynastes peronii tadpoles. Tadpoles were generally more sensitive compared to the two fish species. Differences in responses were observed amongst CMW1 and CMW2, which likely relates to differences in physico-chemical properties between sites. Our results have identified several candidate vertebrate and invertebrate species that show promise for ongoing monitoring of water quality and toxicity risk in Central Queensland, Australia.

Effects of coal mine wastewater on locomotor and non-locomotor activities of empire gudgeons (Hypseleotris compressa)

Coal mining represents an important industry in many countries, but concerns exist about the possible adverse effects of minewater releases on aquatic animals and ecosystems. Coal mining generates large volumes of complex wastewater, which often contains high concentrations of dissolved solids, suspended solids, metals, hydrocarbons, salts and other compounds. Traditional toxicological testing has generally involved the assessment of acute toxicity or chronic toxicity with longer-term tests, and while such tests provide useful information, they are poorly suited to ongoing monitoring or rapid assessment following accidental discharge events. As such, there is considerable interest in developing rapid and sensitive approaches to environmental monitoring, and particularly involving the assessment of sub-lethal behavioural responses in locally relevant aquatic species. We therefore investigated behavioural responses of a native Australian fish to coal mine wastewater, to evaluate its potential use for evaluating sub-lethal effects associated with wastewater releases on freshwater ecosystems. Empire gudgeons (Hypseleotris compressa) were exposed to wastewater from two dams located at an open cut coal mine in Central Queensland, Australia and activity levels were monitored using the Multispecies Freshwater Biomonitor® (LimCo International GmbH). A general decrease in locomotor activity (i.e., low frequency movement) and increase in non-locomotor activity (i.e., high frequency movement including ventilation and small fin movement) was observed in exposed fish compared to those in control water. Altered activity levels were observable within the first hour of exposure and persisted throughout the 15-d experiment. Results demonstrate the potential for using behavioural endpoints as tools for monitoring wastewater discharges using native fish species, but more research is necessary to identify responsible compounds and response thresholds, and to understand the relevance of the observed effects for populations in natural receiving environments.

Locomotor and behavioural responses of empire gudgeons (Hypseleotris compressa) exposed to coal mine wastewater.

Coal mining generates large quantities of complex effluent and may pose a threat to aquatic wildlife. Despite this, few studies have explored the consequences of exposure to mine wastewater on aquatic organisms, and this is particularly true for the Australian environment. We investigated sub-lethal behavioural responses in a native Australian fish exposed to wastewater from two releasing dams (CMW1 and CMW2) located at an open cut coal mine in Central Queensland. Swimming activity and movement of empire gudgeons (Hypseleotris compressa) were assessed during a two-week exposure using video-tracking software. Increased activity was observed in exposed fish after 7 and 14 days. Specifically, we found a significant increase in the mean velocity and mobility of fish exposed to CMW1 treatments. Exposed fish also spent on average 23% more time in the peripheral zone compared to controls after 14-d exposures. A similar response pattern was observed in fish exposed to CMW2, but differences between treated and control fish did not generally reach statistical significance. Alterations to normal swimming activity and movement patterns can be indicative of a stress response in fish, and could subsequently lead to negative population-level impacts by increasing the conspicuousness of exposed individuals to predators, or by altering foraging abilities. More research is warranted to explore relationships between behavioural and physiological outcomes, including endocrine disruption, and subsequent population-level outcomes in aquatic organisms at risk of exposure to coal process-affected water.

Vegetation succession and soil infiltration characteristics under different aged refuse dumps at the Heidaigou opencast coal mine

Vegetation succession and soil infiltration characteristics under five different restoration models of refuse dumps including different-aged revegetated sites (1995, 1998, 2003 and 2005) in the northern, eastern and western open-pit coal mine dump and a reference site with native vegetation, which had never been damaged by coal mining activities on the Heidaigou Open Cut Coal Mine were studied. Changes in the plant species, soil properties and infiltration rates were evaluated at the different refuse dumps. The results indicated that the number of herbaceous species, plant cover, biomass, fine particles, and total N, P and SOM increased significantly with increasing site age. However, the number of shrub species decreased since revegetation, its cover increased from 17% to 41% initially and subsequently decreased to the present level of 4%. The natural vegetation community and the northern refuse dump had the highest cumulative infiltration rates of 3.96 and 2.89 cm s−1 in contrast to the eastern and western refuse dumps and the abandoned land, where the highest cumulative infiltration rates were 1.26, 1.04 and 0.88 cm s−1, respectively. A multiple linear regression analysis indicated that the infiltration rate was primarily determined by the silt percentage, SOM, plant coverage and the variation in soil bulk density. Our results provide new ideas regarding future soil erosion controls and sustainable development at open-pit coal mine refuse dumps.

Drill monitoring results reveal geological conditions in blasthole drilling

•Monitor-while-drilling and geophysical logging data have been acquired for blast holes in an open cut coal mine•Comparison of results show that MWD results respond to the variations in geology revealed by the geophysical logs.•MWD data can be used to predict sonic velocity.•MWD data can be used for geological and geotechnical analysis including blast design.

Simulation and animation model to boost mining efficiency and enviro-friendly in multi-pit operations

A discrete-event system simulation and animation program was developed to enhance the efficiency of a truck-excavator operation and reduce the environmental impact of haulage in an open-cut coal mine with multiple-pit operations. In any mine, a key objective is to have sufficient equipment for production and not to have excess to where it becomes counterproductive. Due to the advent of responsible mining, environmental regulations, and eco-friendly practices, these factors must also be considered in the analysis. Simulation studies can be financially advantageous for both the optimization of existing mine operations and new development phases in a mine. This study is a new approach to use discrete-event system simulation for mine systems, in order to investigate and possibly reduce environmental impact considering mining haulage performance and production target. A hypothetical layout of a surface coal mine with two pit operations was used for the simulation and animation model. The simulation model includes the animation of the operation. Animation is helpful to enhance the benefit of a mine simulation model. GPSS/H® and Proof Professional® were the software used for the investigation.

A comparison of the energy consumption and carbon emissions for different modes of transportation in open-cut coal mines

Transportation accounts for 80% of open-cut coal mine carbon emissions. With regard to the energy consumption and carbon emissions of transportation within an open-cut mine, this paper systematically compared the work and energy consumption of a truck and belt conveyor on a theoretical basis, and constructed a model to calculate the energy consumption of open-cut mine transportation. Life cycle carbon emission factors and power consumption calculation model were established through a Process Analysis–Life Cycle Analysis (PA–LCA). The following results were obtained: (1) the energy consumption of truck transportation was four to twelve times higher than that of the belt conveyor; (2) the CO2 emissions from truck transportation were three to ten times higher than those of the belt conveyor; (3) with the increase in the slope angle for transportation, the ratio of truck to belt conveyor for both energy consumption and carbon emissions gradually decreased; (4) based on 2013 prices in China, the energy cost of transportation using a belt conveyor in open-cut coal mines could save 0.6–2.4Yuan/(tkm) compared to truck transportation.

Using Radon-222 as an Indicator of Atmospheric Mixing Depth in ME-2 for PM2.5 Source Apportionment

We isolated diurnal timescale contributions to a 6-year hourly radon record and incorporated them in ME-2 as a proxy for changes in atmospheric mixing depth in an attempt to improve the source apportionment of fine atmospheric particulate matter (PM_(2.5)). Results from this radon-based implementation of ME-2 are directly compared with the more traditional ME-2 implementation where wind speed is used, as a proxy for changes in mixing depth. The radon-based version more accurately reproduced daily PM_(2.5) source contributions, as evidenced by better correlations with the results from the corresponding bi-linear model. The versions of ME-2 employed in this study were modified to account for calm wind conditions separately, and a recently updated solution approach was adopted. Source apportionment for the radon-based ME-2 implementation was most successful for the finer, primary emissions (Smoke, Autos, Industry) that are more easily suspended and whose concentrations are more directly tied to changes in atmospheric mixing depth. Incorporation of the diurnal radon signal in ME-2 improved the estimated source strength distributions of the Smoke, Autos and Industry sources with respect to the township of Muswellbrook. It also resulted in a more consistent anti-correlation between these 3 source types and atmospheric mixing depth than for the wind speed case. These results confirm that near surface radon concentration is more closely tied to atmospheric mixing depth (and therefore pollutant concentrations) than wind speed. The measurement site for this study is a small township in a rural setting, with nearby power stations and open-cut coal mines. Consequently, the distribution and characteristics of anthropogenic aerosol sources are very different than for a typical urban or industrial setting. This is reflected in lower correlation between the multi-linear models and the corresponding bi-linear models, indicating that the performance of multi-linear models is affected by the nature of the distribution of sources.