J. L. Fernandez-Turiel

Trace elements in coal and their behaviour during combustion in a large power station

The trace elements (As, B, Ba, Be, Bi, Cd, Co, Cr, Cs, Cu, Ga, Ge, Hg, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ta, Th, Tl, U, V, W, Y, Zn, Zr and REE) in a subbituminous coal and their behaviour during combustion in a large power station were characterized by their content and distribution in the fuel (organic and/or inorganic affinities) and in the combustion wastes (partition and volatility). Samples were fractionated by density and magnetic separations and cascade impactors. Quantitative analyses were performed by X-ray diffraction, ICP-MS, ICP-AES, AAS and ICP-AES with hydride generation. Among the findings is the important role of anhydrite (CaSO4) in the sorption of trace elements such as As, B, Ge, Se, Pb, Mo, Zn and Tl from flue gas and in the reduction of emissions of these potentially toxic elements. Calcium oxide has a high sorption capacity for some of the elements studied. This sorption phenomenon and the condensation, mainly as fine fly ash particles, of important fractions of the trace elements during the cooling of flue gas significantly reduce the gaseous emissions of potentially toxic trace elements from coal combustion in the power station studied.

Geological controls on the mineralogy and geochemistry of the Beypazari lignite, central Anatolia, Turkey

Abstract The raw coal from the Cayirhan mine, Beypazari basin, Turkey contains an average of 28.5% mineral matter, consisting up to 80% zeolites. The coal seam is split by a 1-m-thick tuffaceous siltstone into the upper, first (Tv) and lower, second (Tb) seams, which contain essentially different zeolites. The first seam contains Ca-rich zeolites (clinoptilolite/heulandite) whilst the second seam contains Na-rich zeolites (analcime). Experimental work has shown that a Na-rich activation solution will produce Na-rich zeolites when the original volcanic glass is Na-rich, but will produce Ca-rich zeolites when the volcanic material is Ca-rich. It is thought that a Na-rich activation solution, derived from contemporaneous volcanics in the Beypazari basin, reacted with volcanic tuffs of different chemical composition to produce the vertical variability in the mineral matter of the two seams. Trace element analyses of the raw coal showed that they are enriched in As, B, Cr, Ni and Zr when compared to world-wide averages of coal. They are also enriched in the major elements Na and K. These elements are probably also derived from a volcanic source. Barium and Sr show a clear affinity for analcime, whilst Li, Cr, Ni, Cu, Zn, Co and Ga show a clear affinity for clinoptilolite/heulandite. Trace elements showing a positive correlation with the organic matter are Mn, B, Be, Ge, Y, Zr, Nb, Hf, W and U. Manganese, U, Th, Sc, Ge and HREE (heavy rare earth elements) show correlations with phosphate. Trace elements showing correlation with both Fe and S contents are Co, Mo, Ta, Pb and IREE (intermediate rare earth elements). Arsenic and V seem to have mixed affinities with sulphides and zeolites, and organic matter and zeolites, respectively. Although a proportion of the As, B and S are retained in the ash during coal combustion, due to the sorption mechanism of CaO derived from the clinoptilolite/heulandite decomposition, significant emissions of these elements may arise from the Cayirhan thermal power station due to the anomalously high concentrations of these elements in the Beypazari coal. The high total alkali metal content of these coals exceeds the recommended maximum for steam coal, but it is believed that sodium occurring in a mineralogical form such as analcime is not as likely to contribute to boiler fouling as organically-associated sodium.

Mobility of heavy metals from coal fly ash

The mobility of Cd, Co, Cu, Ni, Pb, Sb, and Zn from six different coal-fired power plant fly ashes that show a wide compositional range was examined using a sequential extraction procedure in order to assess their mobility when these wastes are ponded or landfilled. The extraction sequence was as follows: (1) water extractable, (2) cation exchangeable (CH3COONH4 at pH 7), (3) surface oxide-bound cations (CH3COONH4 at pH 5), (4) Fe oxide-bound cations (HONH3Cl), and (5) residual (HF, HCl, HNO3, 2∶1∶1). The heavy metal contents in the extraction solutions were determined by anodic (Cd, Cu, Pb, Sb, and Zn) and cathodic (Ni and Co) stripping voltammetry. The results reveal differences in the total contents of the selected trace elements among the fly ash samples, which must be related to differences in coal composition and combustion technology. The extractable fraction under natural conditions ranges from 1.5 to 36.4 percent of the total element content. Cadmium, Co, Cu, and Zn show the highest extractable fraction (10.8–18.9 percent on average). Cadmium is the most easily water-extractable element, while Co, Cu, and Zn increase their mobility as the severity of the extraction increases. Cobalt, Ni, Pb, and Zn are mainly associated with the surface oxide-bound and Fe oxide-bound fractions. Nickel, Pb, and Sb have low mobility potentials (5.3–6.6 percent as extractable fraction), but Sb presents a relatively high water-extractable fraction.

Environmentally important elements in fly ashes and their leachates of the power stations of Greece

The relative mass of major and trace elements that potentially can be released from the fly ashes generated in the main Greek power plants (Megalopolis A, Amynteon, Agios Dimitrios, Ptolemais, and Kardia) when they are landfilled and exposed to water have been determined. These fly ashes were subject to a one-stage leaching procedure using the Synthetic Groundwater Leaching Procedure (SGLP) test to simulate this situation. The elements Si, Al, Fe, Ti, Ca, Mg, Na, K, S, Ag, As, B, Ba, Be, Bi, Br, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Ho, I, La, Li, Lu, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Tb, Th, Tl, Tm, U, V, W, Y, Yb, Zn, and Zr have been studied. Results show that the elements with the highest potential hazard for the environment are S, Ca, Br, I, Mo, and Sr. The elements with a moderate mobility are K, Na, Ti, B, Ba, Cd, Cr, Cs, Li, Rb, Sb, Se, Sn, W, and Zn. Si, Al, Fe, Mg, Ag, As, Be, Bi, Ce, Co, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Ho, La, Lu, Mn, Nb, Nd, Ni, Pb, Pr, Sc, Sm, Ta, Tb, Th, Tl, Tm, U, V, Y, Yb, and Zr have a low mobility and, consequently, a low potential hazard for the environment.

Geological controls on the coal quality of the Mequinenza subbituminous coal deposit, northeast Spain

Abstract The results of geological, petrographical, geochemical and mineralogical studies, performed to determine the coal-forming paleo-environmental conditions which gave rise to anomalous enrichments in organic sulphur, molybdenum and uranium in the Oligocene Mequinenza subbituminous coal deposit of northeastern Spain, are summarized. This paper demonstrates the major influence exerted by the paleohydrology of the depositional framework on the early diagenetic evolution of the precursor peat deposits. The S, Mo and U enrichments, the preservation of aragonite and chlorophillinite, and the high degree of gelification of the Mequinenza coal are a consequence of alkaline syngenetic conditions in the depositional environment. Similar conditions can be inferred for many Mesozoic and Tertiary coal deposits in the Mediterranean region (Mallorca, Sardinia, Hungary, Bulgaria, Serbia, Greece and Turkey). However, the source of sulphur may have been different and have included Triassic and Early Jurassic sulphate recycling scenarios or volcanic sources. Whatever the source, sulphur enrichment is always influenced by the alkaline depositional environments developed in basins generated during the Alpine Cycle in circum-Mediterranean mobile belts.

Assessment of a Smelter Impact Area Using Surface Soils and Plants

The concentrations of 37 trace elements (Ag, Ba, Be, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Ga, Gd, Ge, La, Li, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sm, Sn, Sr, Tb, Th, Tl, U, V, W, Y, Yb, Zn and Zr) were determined by ICP-MS in surface soils and plants (Sida rhombifolia) sampled around a lead smelter in Lastenia, Province of Tucuman, NW Argentina. Soil and plant patterns of Pb, Cd, Ag, Zn and Cu demonstrate the effects of pollutant dispersion plumes following the prevalent wind directions. The high element concentrations observed, especially Pb (> 5,000 mg/kg), could cause serious environmental problems in areas of close proximity to the smelter. Consequently, measures to assess potential consequences for the local population should be considered to determine if measures to protect the environment are necessary.

Evolution of ocean-island rifts: The northeast rift zone of Tenerife, Canary Islands

The northeast rift zone of Tenerife presents a superb opportunity to study the entire cycle of activity of an oceanic rift zone. Field geology, isotopic dating, and magnetic stratigraphy provide a reliable temporal and spatial framework for the evolution of the NE rift zone, which includes a period of very fast growth toward instability (between ca. 1.1 and 0.83 Ma) followed by three successive large landslides: the Micheque and Guimar collapses, which occurred approximately contemporaneously at ca. 830 ka and on either side of the rift, and the La Orotava landslide (between 690 +/- 10 and 566 +/- 13 ka). Our observations suggest that Canarian rift zones show similar patterns of development, which often includes overgrowth, instability, and lateral collapses. Collapses of the rift flanks disrupt established fissural feeding systems, favoring magma ascent and shallow emplacement, which in turn leads to magma differentiation and intermediate to felsic nested eruptions. Rifts and their collapses may therefore act as an important factor in providing architectural and petrological variability to oceanic volcanoes. Conversely, the presence of substantial felsic volcanism in rift settings may indicate the presence of earlier landslide scars, even if concealed by postcollapse volcanism. Comparative analysis of the main rifts in the Canary Islands outlines this general evolutionary pattern: (1) growth of an increasingly high and steep ridge by concentrated basaltic fissure eruptions; (2) flank collapse and catastrophic disruption of the established feeder system of the rift; (3) postcollapse centralized nested volcanism, commonly evolving from initially ultramafic-mafic to terminal felsic compositions (trachytes, phonolites); and (4) progressive decline of nested eruptive activity.

Leachability of Major and Trace Elements of Fly Ash from Ptolemais Power Station, Northern Greece

Major (Si, Al, Fe, Ti, Ca, Mg, Na, K, and S) and trace (Ag, As, B, Ba, Be, Bi, Br, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Ho I, La, Li, Lu, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Tb, Th, Tl, Tm, U V, W, Y, Yb Zn, and Zr) elements were determined in experimental leachates of fly ash from the Ptolemais coal-fired power plant (Northern Greece). This plant has a total capacity of 620 MW and consumes lignite from the Ptolemais basin. Experimental leaching was carried out using one stage and column leaching procedures. These leaching experiments allowed for the characterization of the relative mass leached and the element behavior in function of time. Relative mass leached is generally low. Only Sr and Mo are lost during the first five pore volumes of the leaching. The foremost transformations are relatively fast, implying mainly Ca and S reactions and an important lowering of pH values. The results can be used in the disposal assessment of this combustion byproduct to model more accurately the behavior of major and trace elements released during fly ash landfilling.

Spatial and seasonal variations of water quality in a Mediterranean catchment: the Llobregat River (NE Spain).

The Llobregat and Ter Rivers, typical Mediterranean catchments in Northeast Spain, supply water to more than 4.5 million inhabitants residing in the metropolitan area of Barcelona. The objective of this work is to study the factors that influence the surface water quality of Llobregat catchment. As such, spatial and temporal variations of more 50 water chemical parameters were monitored in 10 sampling sites for a period that extended from July 1996 to December 2000. The temperature, pH and conductivity were measured at sites, whereas metals were analysed using ICP-OES and ICP-MS instrumental techniques. The head waters of the Llobregat River catchment flow through detrital Mesozoic–Cenozoic sedimentary rocks resulting in calcium bicarbonate-type water with low mineral content. The high water quality of the waterhead is deteriorated in the upper-middle part of the catchment due to: occurrence of evaporite-bearing geological formations, and the mining and industrial activities related to potash exploitation. As a result, an obvious increase in Na, K, Mg, Cl−, Br, Rb, and Sr concentrations is reported leading to a sodium (potassium) chloride water type. This saline hydrochemical fingerprint persists downstream. This important feature renders the low water quality of the Llobregat River to be adequate for drinking supply purposes. In addition, the industrial and residential activities, specially at the lower part of the catchment, increases P, B, Mn, Fe, Pb, Al, Cr, Co, Ni, Cu, Zn, As and Sb water concentrations.

Geological factors influencing the concentration of trace elements in the Philippi peatland, eastern Macedonia, Greece

Abstract Six peat samples obtained from the Holocene and the Weichselian of the Philippi peat deposit, eastern Macedonia, Greece, were analyzed for 48 trace elements by Inductively Coupled Plasma–Mass Spectrometry (ICP–MS). The ash contents of these samples were also determined. Most of the trace elements are associated with the minerals in the peat, while Ge, Mo, Pb, Se, Ta, Tl, U, and W display a greater affinity with the organic matter. Compared with crustal averages (Clarke concentrations), the Philippi peat is enriched in some elements (Ag, As, Au, Cd, Mo, Se, Te, U, and W) because of the respective mineralizations in the area. The Philippi peat is also enriched in Cr, Cu, Mo, Pb, Sc, Sn, T, V, Y, and Zn in comparison with typical fen peats, as well as in As, Cr, Mo, Se, and U in comparison with typical coals. Climatic and hydrogeological conditions strongly influenced the peat-forming environment resulting in a differentiation between Holocene and Weichselian peat. Generally, the Holocene peat contains lower concentrations of trace elements in the northern and southern part of the fen, than the Weichselian one. The opposite trend is observed in the fen area close to the western basin margins.