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Abstract: The perhydrous Batalha coal (Portugal) is found in the Cabaços and Montejunto Formation of the Oxfordian–Kimeridgian, Upper Jurassic age. From the macroscopic point of view, its appearance is similar to other perhydrous coals. Microscopically, the maceral group of huminite is the main organic component (96%), ulminite being the most important petrographic component, followed by textinite with resinite (4%) lumina filled. The huminite random reflectance is 0.33%. This coal is characterized by high H/C atomic ratio, and anomalous physical and chemical properties that are characteristic of perhydrous coals such as: (i) the absence of any correlation between reflectance and the chemical rank parameters; (ii) a lower real density than that of non-perhydrous coals; (iii) a high hydrogen content; and (iv) suppressed reflectance. Using its calorific value (moist, ash-free basis) as rank parameter, Batalha coal must be considered a subbituminous A coal. Hydrogen enrichment due to the presence of resinite has influenced the technological properties of this coal, namely: (i) reduction of the thermostability and decrease in the temperature of initial thermal decomposition due to, among other reasons, the existence of aliphatic structures with low dissociation energy bonds resulting from the presence of resinite; (ii) from the DTG profile, the volatile matter combustion and char combustion is not evident; (iii) development of chars made up of isotropic particles with angular edges, which is typical of a low rank coal; (iv) the evolution trend of gaseous compounds (CO, CO2 and CH4) during pyrolysis; and, (v) an increase in its calorific value due to its hydrogen content. The study of this coal which is interbedded in Jurassic formations in the Lusitanian Basin of Portugal is a new contribution to the assessment of the evolution of organic matter in this area. [ABSTRACT FROM AUTHOR]

Abstract: The Buçaco Basin includes a Carboniferous/Permian sequence that comprises, from bottom to top, the following stratigraphic sequence: Algeriz Formation, Vale da Mó Formation and Monsarros Formation. Algeriz Formation is constituted by deposits of basal breccia with variable thickness and alternating layers of siltstone, mudstone and conglomerate. Vale da Mó Formation corresponds to lacustrine deposits comprising massive red beds in the base, that pass alternatively to silty-mudstones, shales and grey mudstones with organic matter; this formation also includes a thin coal seam. Monsarros Formation includes fluvial conglomeratic deposits prevalent in the base and top, separated by layers of siltstone and mudstone, redder to the top. The Buçaco Basin opens as a pull-apart basin, into the Porto-Coimbra-Tomar shear zone and later is affected by the clockwise (dextral) movement of this N10°W shear zone. The petrographic study of samples from Vale da Mó Formation showed that the organic matter corresponds to a type III kerogen, derived from higher land plants (gas-prone). The thermal maturation level of the strata was determined using random vitrinite reflectance, with values ranging from 0.72% to 0.80% (%Rr). Rock-Eval pyrolysis showed that Vale da Mó Formation is the only one with potential to generate hydrocarbons, an observation consistent with the petrographic characteristics. TOC ranges from 0.08% to 1.52%. Monsarros Formation reported the highest values for S1/TOC index. [Copyright &y& Elsevier]

The Rio Maior Basin (Portugal) is a tectonic depression, filled by a Pliocene sequence that comprises, from floor to roof: (i) kaoliniferous fine sands, (ii) diatomites and lignites, (iii) recent deposits of sandstone and clay. The diatomites and lignites form a small dissimetric syncline with alternating seams. Ten lignite seams were identified and named from floor to roof as F, E, D, C.2, C.1, C, B, A, a and a′. Seams A, D, E and F are considered to be the main seams.The organic fraction consists mainly of macerals of the huminite group, with small percentages of inertinite and liptinite groups. However, the petrographic composition of each seam is distinct, particularly with regards to macerals of the huminite and liptinite groups.Calculation of petrographic indices permitted to plot the coals in facies and palaeoenvironment diagrams. Five facies have been defined: (i) aquatic, (ii) herbaceous swamp, (iii) mixed swamp with forest and herbaceous vegetation, (vi) forest swamp (wetter) and (v) forest swamp (drier).These lignites are humic coals formed from organic matter of terrestrial origin. The peat biomass at the origin of these coals formed from a very diverse vegetation comprising gymnosperms and angiosperms. In seams F, and occasionally in seams E and D, Botryococcus algae have also contributed to the biomass. Peat deposition corresponded to a rheotrophic hydrological regime: the water level always remained above the topographic surface of the basin. Nevertheless, during the deposition of seam A in the northern part of the basin, the water level was slightly below the topographic surface. The organic matter was preserved in anaeorobic conditions. [Copyright &y& Elsevier]

Abstract: In the Douro Coalfield anthracites were exploited for decades (1795–1994). Besides many small mines Douro Coalfield had two principal mining areas (S. Pedro da Cova and Pejão). Coal mining activities cause several impacts on the environment, one of which is the amount of discard or waste which was disposed of all over Douro Coalfield resulting in one of the most significant and severe impacts on the environment. Over 20 waste piles exist in the old mining areas, geographically dispersed, and three of them are presently burning. Their ignition was caused by forest fires during the summer of 2005. Samples from the burning and unburned zones of the waste piles were studied as were the gas from vents and the minerals resulting after combustion. Geochemical processes and mineralogical transformations in the burning coal waste pile were investigated. Microscopic analyses of the samples identified some particular aspects related with combustion: oxidation of pyrite, the presence of iron oxides, organic particles with cracks and rims with lowered (suppressed) Rr, devolatilization vacuoles and some char structures. The occurrence of vitreous (glassy) material as well as Fe–Al spinels in the burning coal waste provide evidences that the combustion temperature could have reached values above 1000°C. Due to combustion, and as expected, the samples studied reported high ash yields. Samples taken from the burning zones reported an increase of As, Cr, Li, Nb, Ni, Pb, Rb, Sr and LREE concentrations and a decrease in Zr and HREE concentrations. Enrichment in Cs, Li and Rb was noted when comparing with the geochemical composition of black shales and world coals composition that is related with the contribution of granitic rocks in the sediments that originated the main lithologies of the Douro Coalfield (carbonaceous shale and lithic arenites). Cluster analyses (R-type and Q-type) were performed to understand the trend between the unburned and burning samples and it seems that some chemical variations are responsible for this separation. Elemental sulphur and salammoniac (ammonium salt) are the coal fire gas minerals neoformed on the surface of piles, near the burning zones. They were identified by different techniques, mainly SEM-EDX, XRD and FTIR. Relatively high concentrations of several aromatic compounds were detected in the gas collected at the studied areas, as well as aliphatic hydrocarbons. The highest concentrations of aromatic hydrocarbons were measured in gas samples from S. Pedro da Cova waste pile. The exposure to hazardous compounds present in the gas is a serious risk to human health and the environment. [Copyright &y& Elsevier]

A new system for the microscopic classification of fly-ash components has been developed by the Fly-Ash Working Group, Commission III of the ICCP and is presented herein. The studied fly-ashes were obtained from the combustion of single coals of varied rank, coal blends, and coals blended with other fuels (biomass, petroleum coke), in different operating conditions and by means of different technologies. Microscopic images of the fly-ash samples were used to test the optical criteria proposed for classifying the fly-ash components. The classification system developed is based on a small number of microscopic criteria, subdivided into six independent levels or categories, three of which are directed at whole particle identification on the basis of nature, origin and type of fly-ash particle, while the other three levels are directed at the smaller section identification on the basis of character, structure and optical texture of unburned carbons. To classify the inorganic components of the fly-ash, the criterion proposed is composition in terms of metallic/non-metallic character. To establish the classification criteria the petrographers involved in the work performed three successive round robins. Evaluation of the results by using firstly descriptive statistics and then the criteria and parameters employed by the ICCP in their accreditation programs indicated that the classification of the fly-ash components was accurate and that there was only a minor bias. The main conclusion of this study was that the proposed criteria are valuable for identifying, and classifying fly-ash components and for describing the optical properties of fly-ash particles. [ABSTRACT FROM AUTHOR]

Abstract: Mining waste resulting from the Douro Coalfield exploitation was emplaced all over the coalfield area. More than twenty coal waste piles were identified, consisting of lithic fragments, normally carbonaceous shales and lithic arenites, sometimes with organic matter and particles of variable size. The main objectives of this work were the petrographic and geochemical characterization of the waste material, which provide information about the potential environmental problems associated with the waste disposal. The methodologies applied were optical microscopy and scanning electron microscopy with X-ray microanalysis for the petrographic studies, proximate analysis (moisture and ash), carbon content determination by LECO analyzer, and inductively coupled plasma mass spectrometry for the geochemical characterization. Petrographic observations demonstrated that the organic fraction is attributed to vitrinite and inertinite macerals. The mineral matter comprises lithic fragments with organic and inorganic layering, clay minerals, quartz, iron oxides, oxidized framboidal pyrite and, rarely, non-oxidized pyrite. Some evidence of weathering was detected and found to be related to the time of exposure to the weathering processes. The geochemical composition of the samples are relatively similar and, as expected, are between the chemical composition of coal and main lithologies of the Douro Coalfield. Based on Pearson''s correlation coefficients, the trace elements with inorganic affinity are Ba, Cr, Ga, Hf, Ni, Rb, Sc, V, and Zr, and the elements with intermediate affinity are S, As, Bi, Pb, U, and W. According to the results of cluster analysis, a sulphide fraction is represented by the association of As, Cd, Cu, Ni, Pb, and Zn. The association of Al, Be, Co, Fe, Ti, and U indicate that these elements are likely to be related with silicate minerals such as clays; the elements Ba, Cr, Li Mn, Rb, Sr, V, Zr, and RRE probably characterize a silicate fraction, perhaps detrital accessory minerals. Generally, the leachable concentrations are not high, and the elements showing highest releases include Ba, Co, Cu, Mn, Ni, and Zn, indicating that these elements are associated with H2O-soluble compounds. Comparing the leaching results with the waste acceptance criteria for landfilling the waste material is classified as non-hazardous wastes. [Copyright &y& Elsevier]

Abstract: Anthracite fly ash from a deactivated Portuguese thermo-electric power plant has been characterized to assess its relationship to the mineral matter in typical feed coal and the potential environmental impacts that might be caused by ash disposal. Several different aspects of the ash were characterized, including the petrographic and mineralogical composition, as well as the chemical composition of both the ash samples and their water leachates. Petrographic analysis demonstrates that the fly ash consists predominantly of glass, followed by char and crystalline mineral particles. SEM-EDX studies were used to complement this approach, revealing a mixture of different inorganic phases and unburnt organic matter. Quantitative XRD analysis further showed that amorphous material (or glass) is the main constituent (60–70%), followed by mullite, quartz, and traces of maghemite. Small proportions of kaolinite and illite also occur in some of the fly ash samples. According to their chemical composition, the fly ashes would be classified as sialic and are within the range of values shown by other European fly ash samples. Relatively low concentrations of elements in leachates from the fly ash could be due to enclosure of most of the elements within the amorphous material, together, possibly, with mobilization of some of the material (e.g. adsorbed ions) from the ashes with storage. The fly ash leachates developed very acidic pH values (between 2.5 and 2.8) under test conditions, attributed to the low-CaO content and the co-firing with fuel oil. [Copyright &y& Elsevier]

Abstract: Serrinha is the largest coal waste pile resulting from mining activities in the Douro Coalfield, Portugal. The exploitation of anthracite in tens of small mines caused some environmental impacts, as is the case of the coal waste piles that exist in old mines and adjacent areas. The Serrinha waste pile is essentially made up of 2million tonnes of shales and carbonaceous shales, deposited in a topographical depression over about 30years. Despite the environmental restoration accomplished in the Serrinha waste pile, some environmental problems seem to persist. In this study a petrographic, mineralogical and geochemical characterization was done in order to recognize and understand these problems. The materials studied were coal waste, sediments and waters from the drainage system and decanting basins, soils from the surrounding areas, leachates from waste material and neoformed minerals formed at the bottom of the waste pile. The main lithologies (carbonaceous shale and lithic arenite) and coal from the Douro Coalfield were also analyzed. Petrographic analysis shows some evidence of weathering (on organic and inorganic matter) related to the time of exposure to the weathering agents and the easy access of air within the waste pile (due to both the poor compaction and the heterogeneity of the material). Mineralogically, the composition of coal waste material has contributions from both the coal and the associated lithologies. R-type cluster analysis of the waste pile material allows two distinct clusters to be identified. In the first cluster a sulfide fraction is represented by the association of As, Cd, Cu, Pb, Ni and Zn, while Fe clustered with Al, Co, and Ti indicates that some of the Fe and the other elements are likely associated with silicate minerals such as clays. The second cluster, represented by Cr, V, Zr, Rb, REE, Mn, Li and Ba, probably represent a silicate fraction, perhaps detrital accessory minerals. The waste pile material, leachates, soils, sediments, neoformed minerals and water analyses indicate the existence of potential environmental impacts due to the acid mine drainage and associated leaching of heavy metals and other elements. [Copyright &y& Elsevier]

Abstract: This paper describes an assessment of char classification system by the Combustion Working Group in Commission III of the International Committee for Coal and Organic Petrology (ICCP). The work of the group culminated in the production of a char atlas after a final round robin exercise. This round robin involved 21 analysts and was an electronic exercise using digitally captured images of individual char particles, rather than actual char blocks. A software program featuring 170 char images was specifically designed to allow operators to identify each char based on a classification system with 9 individual char types; tenuisphere, crassisphere, tenuinetwork, crassinetwork, mixed porous, mixed dense, fusinoid, solid and mineroid. The program electronically recorded all decisions as well as the time taken for each decision to be made. From 170 chars, 128 chars were identified by a majority (>70%) and these chars were then compiled in a char atlas that is now available for download (www.nottingham.ac.uk/~eczehl/charatlas). As would be expected all analysts appeared to become more confident in identifying chars during the exercise, taking less time per image, but with no clear evidence of improvement. Without exception, analysts took longer to make an incorrect decision. [Copyright &y& Elsevier]