J. L. Fernández Turiel

Trace elements in high-S subbituminous coals from the Teruel Mining District, northeast Spain

Abstract The elemental composition of high temperature ash (750°C) and forms of S were studied in 25 coal seams from the Escucha Formation (Middle Albian) in the Teruel Mining District, northeast Spain. The principal analytical method was ICP-MS, but ICP-ES was also used in the determination of some trace elements. The analytical data show wide ranges of trace element cotnents among the coal seams studied, even in the vertical profile of a single coal seam. These wide ranges of the trace element concentrations are attributed to both syngenetic and epigenetic processes. When a comparison was made between the average trace element contents of the Teruel Mining District coals, and those of the average content in worldwide coals, the Teruel coals show slightly higher concentrations of Be and U, and lower concentrations of Ba, Cd, Mn, Pb, Sr and Zr. Further, three main groups of trace elements were differentiated on the basis of the inorganic/organic association: (1) trace elements with inorganic affinity; Ba, Ce, Co, Cr, La, Mn, Ni, Rb and Zr. Between these, Ba, Ce, Cr and Rb show a well defined correlation with the clay mineral content, and Co and Ni with pyritic-S content; (2) trace elements with an intermediate (mixed) affinity; As, Cd, Cu, Dy, Er, Eu, Gd, Ge, Ho, Lu, Mo, Nd, Pb, Pr, Sb, Sm, Sr, Tb, Th, Tm, U, Yb and Zn. In this group, As, Cd, Cu, Ge, Mo, Th, U and Zn show a weak trend associated with the mineral matter and Sr with the organic matter; and (3) Be shows an organic affinity. The high mineral matter content (21.3% HTA) of the Teruel coals may account for the great number of elements with inorganic affinity. This classification represents a general trend, but the results show that the affinities of some trace elements (e.g. As, Sb and Zn) may vary from one coal seam to another in the Teruel Mining District.

Space–time evolution of monogenetic volcanism in the mafic Garrotxa Volcanic Field (NE Iberian Peninsula)

We reconstructed the evolution of the volcanic activity within the central Garrotxa monogenetic Volcanic Field, the youngest volcanic area of the Iberian Peninsula, by investigating the stratigraphy of the volcanic successions and the morphology of the monogenetic eruptive centres. Analysis of this volcanic succession has been conducted following the Unconformity Bounded Stratigraphic Units criteria. The detailed stratigraphy of the volcanic successions shows that the central Garrotxa Volcanic Field (GVF) evolved through four main periods of volcanic activity (Synthems) represented by the eruptive products of the mafic monogenetic volcanoes and associated syn-eruptive reworked deposits (Eruptive Units) and by the inter-eruptive deposits (Epiclastic Units). The distribution and the morphologies of the monogenetic volcanoes suggest that feeder dykes were emplaced under influence of the present stress filed and along pre-existing fractures of the basement. Our facies analysis of the deposits and their distribution shows that migration of volcanism toward the centre of the basin was accompanied by a trend of increasing explosivity. Episodic hydromagmatism in central Garrotxa occurred without a specific geographic locus or obvious temporal correlation. Finally, by integrating field data with the stratigraphy extracted from water wells, we determined the volume of the volcanic deposits. The small average volume of products emitted during each eruptive period, and the long quiescence separating them, allow us to classify the GVF as a low-output rate volcanic field.

Determination of pyritic sulphur and organic matter contents in Spanish subbituminous coals by X-ray power diffraction

Abstract Two analytical methods for the indirect determination of pyritic sulphur and ash contents in Spanish subbituminous coals by means of X-ray diffraction (XRD) are described. An indirect analytical method for pyritic sulphur is used to determine this type of sulphur in high-sulphur coals from the Teruel and Mequinenza mining areas (northeastern Spain). The analytical method is based on the quantification by m eans of XRD of the hematite content resulting from the oxidation of iron sulphides after coal ashing at 750°C. It has been possible to use this analytical method for the particular coals studied because they do not contain iron carbonates or organic-fixed iron in appreciable amounts. It can thus be assumed that the hematite in the ash proceeds exclusively from the oxidation of iron sulphide. The method of determining the ash content in coal by means of XRD was devised in order to analyze small amounts of samples from density separations. The small amount of sample available (some fractions lower than 0.5g) and the need to analyze various parameters (sulphur, mineral and trace element contents) in the sample did not allow us to determine the inorganic content by ashing. The method permits the total recovery of the sample for subsequent analyses and the determination of the different mineral phases. The method devised is based on the quantification of scattering due to the organic matrix in XRD. The organic matrix, as an amorphous matrix, increases the X-ray diffraction background intensity (scattering curve) by amorphous scatterring, to an extent proportional to the organic matter content. The main advantages of this method is its speedy determination (4 min) and the possibility of sample recovery for subsequent analyses.

Synthesis of industrial minerals from fly ash

Publisher Summary This chapter discusses the synthesis of zeolites after alkaline fly ash activation is studied as a function of the sample–solution ratio, chemistry of the solution, and reaction time. The experiments are performed using fly ash from the Teruel power station. The results obtained show the potential application of fly ash for zeolite synthesis after alkaline activation. Higher activation efficiencies are found for the synthesis of the NaP1. The mineral transformations produced during the activation of fly ash allowed to deduce the activated material in fly ash. The experiments demonstrated that the time needed for an effective activation is reduced by increasing the temperature and solution concentration.