3D geometallurgical characterization of coal mine waste rock piles for their reprocessing purpose

Some waste rock piles create some problems such as acid mine drainage (AMD), leaching of heavy metals, and slope stability concerns. These problems are related to the flow of water through the rock pile. Understanding the physical and hydrological properties of the waste rock piles is important for flow and solute transport modeling. To study physical properties and unsaturated flow in rock pile, some soil samples were collected from surface of the large coal waste rock pile and tested for some common geotechnical parameters in the laboratory. The results showed that materials are so heterogeneous and highly supporting segregation and natural gravity sorting of waste rock materials from top to toe. Numerical simulation was performed to investigate the unsaturated flow conditions in the pile. The results obtained showed that pile is unable to fully saturate and drain during the simulated period. It was also found that high evaporation and also coarse grain nature of waste rock materials results holding few amounts of water in the system.

Mechanical properties and durability of concrete containing coal mine waste rock, F-class fly ash, and nano-silica for sustainable development

Reduction and utilization of coal mine waste rock in China: A case study in Tiefa coalfield

This research investigates the properties of concrete utilizing coal mine waste rock (CMWR) as a substitute for river sand. The workability of fresh concrete is assessed through slump tests, revealing a decrease in a slump as the percentage of CMWR replacement increases. The density of the concrete mixtures increased with curing time, and the compressive strength also exhibited an upward trend but with lower values compared to the control concrete when CMWR was used as a replacement. The reduction in compressive strength ranges from 11.4% to 47.6% for CMWR replacement levels of 25% to 100%. The study also examines the influence of climate conditions, including temperature and humidity. Shrinkage deformation tests indicate that CMWR concrete demonstrates higher plastic and dry shrinkage than river sand concrete. CMWR concrete exhibits significantly higher drying shrinkage, attributed to the enhanced water absorption capacity of CMWR particles. These findings provide valuable insights into the performance of concrete incorporating CMWR and propose potential strategies for mitigating its effects. The research outcomes contribute to the knowledge base in the field and offer practical implications for the operation of CMWR in concrete applications

Temporal trends of dissolved weathering products released from a high Arctic coal mine waste rock pile in Svalbard (78°N)

98/03292 A study of producing light refractory bricks of mullite by using coal gangues as raw materials: Ni, W. et al. Dizhi Zhaokuang Luncong, 1997, 12, (4), 79–86. (In Chinese)

Around 25 million tons of coal mine waste rock (CMWR) are stored in many places in Morocco due to coal mining activities. As a result, air and water quality of the neighborhood is polluted and large lands are occupied. This study aimed to investigate the use of an integrated and circular approach based on coal recovery and waste rock recycling. More than 30 drill core samples were taken from the big coal dump reaching a depth of 60 m and analyzed to evaluate the chemical composition variability. Froth flotation was used to recover coal particles using diesel as a collector and Methyl Isobutyl Carbinol as a frother, 100 g/t each. The tailings of coal flotation process (CFT) were used to manufacture fired bricks at a pilot scale. The results of this study highlighted the possibility to valorize the whole waste material toward an objective of zero waste in the future. On a basis of 100t feed, (i) 10-15t can be recovered as high-quality anthracite coal with a calorific value over 7500 kcal/kg using flotation processing at a recovery yield over 80%, (ii) 45-60t can be reused as shales for bricks production with a compressive strength over 16MPa, (iii) 20-30t can be reused as aggregates for concrete production with a compressive strength over 20MPa. The remaining material can be reused as sand. The recovered anthracite can be reused to manufacture coal briquettes or used at it is in the thermal power plant next to the dump site.

Applications of inductively coupled plasma mass spectrometry and laser ablation inductively coupled plasma mass spectrometry in materials science

Recent applications on isotope ratio measurements by ICP-MS and LA-ICP-MS on biological samples and single particles

BackgroundSafety assessment of nanoparticles (NPs) requires techniques that are suitable to quantify tissue and cellular uptake of NPs. The most commonly applied techniques for this purpose are based on inductively coupled plasma mass spectrometry (ICP-MS). Here we apply and compare three different ICP-MS methods to investigate the cellular uptake of TiO2 (diameter 7 or 20 nm, respectively) and Ag (diameter 50 or 75 nm, respectively) NPs into differentiated mouse neuroblastoma cells (Neuro-2a cells). Cells were incubated with different amounts of the NPs. Thereafter they were either directly analyzed by laser ablation ICP-MS (LA-ICP-MS) or were lysed and lysates were analyzed by ICP-MS and by single particle ICP-MS (SP-ICP-MS).ResultsAll techniques confirmed that smaller particles were taken up to a higher extent when values were converted in an NP number-based dose metric. In contrast to ICP-MS and LA-ICP-MS, this measure is already directly provided through SP-ICP-MS. Analysis of NP size distribution in cell lysates by SP-ICP-MS indicates the formation of NP agglomerates inside cells. LA-ICP-MS imaging shows that some of the 75 nm Ag NPs seemed to be adsorbed onto the cell membranes and were not penetrating into the cells, while most of the 50 nm Ag NPs were internalized. LA-ICP-MS confirms high cell-to-cell variability for NP uptake.ConclusionsBased on our data we propose to combine different ICP-MS techniques in order to reliably determine the average NP mass and number concentrations, NP sizes and size distribution patterns as well as cell-to-cell variations in NP uptake and intracellular localization.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-016-0203-z) contains supplementary material, which is available to authorized users.

Metal speciation and bioavailability in acid mine drainage from a high Arctic coal mine waste rock pile: Temporal variations assessed through high-resolution water sampling, geochemical modelling and DGT

Based on laboratory analysis of soil samples collected from abandoned coal mine in Datong area, content of heavy metals in the soils was monitored and the soils were evaluated for heavy metal pollution. The spatial distribution of heavy metals was study with means of Kriging method by under ArcGIS environment in the abandoned coal mine in Huainan area. The results show: (1) the content of 5 types of heavy metals( Hg, Cd, Cr, Pb, Cu) were all higher than Huainan area background value of soil elements, among of these heavy metals, the enrichment of Cd was higher and polluted quite seriously; the enrichment of Hg, Cr, Pb and Cu was lower, and polluted lightly comparatively. (2) The coal mine waste rock pile and abandoned chemical plant were the main pollution sources. (3) The heavy metal concentrations and space distribution were mainly affected coal mine waste rock pile, and abandoned chemical plant. (4) Positive correlation between concentrations of most heavy metals was significant, and there is a certain relationship between concentrations of heavy metals and organic matter, nitrogen, available phosphorus. On the basis of the above research, some countermeasures were put forward for ecological restoration in Datong abandoned coal mine.

Rare-Earth Doping Graphitic Carbon Nitride Endows Distinctive Multiple Emissions with Large Stokes Shifts

In the last few decades, the utilization of coal to generate electricity was rapidly increasing. Consequently, the production of coal combustion ash (CCA) as a by-product of coal utilization as primary energy sources was increased. The physical and geochemical characteristics of CCA were site-specific which determined by both inherent coal-source quality and combustion condition. This study was intended to characterize the physical, chemical and mineralogical properties of a coal-combustion ash (CCA) from a site specific power plant and evaluate the leachate characteristic of some scenario on the co-placement of CCA with coal-mine waste rock. The physical properties such as specific gravity, dry density, porosity and particle size distribution were determined. Chemically, the CCA sample is enriched mainly in silica, aluminum, iron, and magnesium along with a little amount of calcium and sodium which includes in the class C fly ash category. Moreover, it is found that the mineral phases identified in the sample were quartz, mullite, aragonite, magnetite, hematite, and spinel. Co-placement experiment with mudstone waste rock shows that the CCA, though it has limited contribution to the decreasing permeability, has important contributed to increase the quality of leachate through releasing higher alkalinity. Moreover, addition of CCA did not affect to the increase of the trace metal element in the leachate. Hence, utilization of CCA by co-placement with coal mine waste rock in the dumping area is visible to be implemented.

Background: Resource-saving developments using industrial waste as a man-made raw material for the production of binders allow for the expansion of the raw material base and improve the environmental situation in regions through the recycling of large-scale industrial waste, including coal mining waste. The dump coal mining unburned rocks of the Khmelnitskaya mine and the Sverdlov mine of Ukraine have been studied in the work. Methods: The mineral composition of the rocks was determined by X-ray phase analysis, the oxide composition and micrographs of the surface of cement clinker particles were determined by electron probe microanalysis using scanning electron microscope. Results: Clinochlore and muscovite have been detected in coal mining waste rock. These minerals are typically present in clays used in the production of Portland cement clinker. High adsorption and hydraulic activity of coal mining waste rock has been established. Conclusions: The use of unburned coal mining rock in the raw mix, instead of the clay component (5.8−10.2%), was demonstrated in the production of Portland cement clinker. The resulting cement clinker matches Portland cement in terms of its oxide and mineralogical composition and physical and mechanical properties. Significanc: The applied direction of using industrial waste as a man-made raw material for the production of binders has received further development.