Concentration Of Trace Elements In Coal Research Articles

Enrichment of trace element concentrations in coal and its combustion residues and their potential environmental and human health impact: Can Coal Basin, NW Turkey as a case study

In this study, the variation of trace element concentrations (total of 48 trace elements including rare earth elements) in coal, coal ash and fly ash were examined and compared with coal Clarke values. Results showed that the average concentrations of trace elements including As, B, Cu, Ce, Co, Cs, Gd, Hf, La, Lu, Mo, Nd, Nb, Pr, Pb, Sc, Sm, Ta, Tb, Th, U, V, W, Y, Yb, Zn and Zr in the Can Basin coals are higher than their respective Clarke values for world low-rank coals. The elements As, Cu, Co, Cs, Mo, Nb, Sc, Pb, Pr, Th, U, V, Zn and Zr are enriched in coal ashes, whereas As, Co, Nb, Sc, U and V are enriched in fly ashes. Among the elements, maximum enrichment in coal was observed for As, with the average concentration of 253.5 ppm As in the Can Basin coals, while the coal Clarke value is 14 ppm and world average value is 8.3 ppm. From the ecotoxicological point of view, combustion residues formed by indoor combustion of coal and/or in thermal power plants may be a hazard to the environment and to aquatic and terrestrial life including human beings, particularly As, trace elements and released radioactive elements.

Enrichment of trace element concentrations in coal and its combustion residues and their potential environmental and human health impact: Can Coal Basin, NW Turkey as a case study

Enrichment of trace element concentrations in coal and its combustion residues and their potential environmental and human health impact: Can Coal Basin, NW Turkey as a case study

Distribution of trace elements in coal and combustion residues from five thermal power plants in India

Abstract The rapid increase of coal fired thermal power generation in India has resulted in increased generation of fly ash and bottom ash of various properties. In this study, coal and ash samples collected from five different thermal power plants across India were characterized and quantified to determine trace element concentration so as to understand their distribution, enrichment, and partitioning behavior. Concentrations of Pb, Cu, Cd, Zn, Fe, Mn, Cr, Ni, Mg, Li, Co, Hg, and As, were estimated in fly ash, bottom ash, and coal samples. The concentrations of toxic elements, such as As, Hg, Pb, and Cd in fly ash were in the range of 0.19–0.35 μg/g, 0.51–2.13 μg/g, 7.6–35.3 μg/g, and 0.6–0.93 μg/g, respectively, whereas in bottom ash, concentrations of these toxic elements were in the range of 0.1–0.29 μg/g, 0.41–1.58 μg/g, 8.8–28.28 μg/g, and 0.49–0.79 μg/g, respectively. Cadmium and As were the lowest in both coal and ash samples, whereas Fe, Mn, and Zn were found to be the highest. The elements were classified into three groups based on their volatility. All the elements were found to be enriched more in fly ash than in bottom ash. To evaluate the influence of the elements on local environment, enrichment factor with respect to Fe was calculated for all the elements in fly ash and bottom ash. The enrichment ratio, relative enrichment index, and partitioning behavior were used to describe the differences of trace-element concentrations in coal, fly ash, and bottom ash. Among the elements, maximum enrichment was observed for Mn in both fly ash and bottom ash.

Trace elements in coal derived liquids: analysis by ICP-MS and Mössbauer spectroscopy

Concentrations of trace elements in coal derived liquids have been investigated by inductively coupled plasma-mass spectrometry (ICP-MS) and by Mössbauer spectroscopy. Liquefaction extracts prepared from the Argonne Premium Coals and a coal tar pitch have been examined. Microwave digestion in concentrated nitric acid has been shown as a suitable method for determining trace element concentrations in coal derived liquids by ICP-MS—for sample sizes as small as 3–20 mg. High concentrations of Fe were found for all extract samples (<265–1474 ppm). Ti, Cr, Mn, Co, Ga, Sb, Cs and Ba were measurable. Concentration distributions of trace elements found in the extracts bore little relation to the corresponding distributions in the original coals. The proportions of individual trace elements present in the original coals and found in the extracts, varied widely. Mössbauer spectroscopy of the extracts indicated that the high Fe-concentrations corresponded to the presence of organometallic-Fe compounds—and not to pyritic iron. There is evidence suggesting the presence of material derived from iron-storage proteins such as ferritin, but final proof is lacking. Our data suggest that other metallic ions detected in these coal derived liquids may be present in association with the organic material. Concentrations of paramagnetic metal species were found to be of the same order of magnitude as ESR spin-densities already found in coal liquids. Both types of paramagnetic species are suspected of causing loss of signal in solid state 13C NMR.

Studies of trace element distribution at the coal-rock interface

Trace element concentrations in coal of the Istrian coal basin were determined by PIXE spectroscopy. The PIXE milliprobe was used to obtain positional data of elements on a submillimeter scale, while the microprobe facility served for the elemental mapping on a μm scale. The elemental distribution pattern on the coal-rock interface serves as a basis for the investigation of possible diffusion processes which could be going on in that particular boundary region.

The occurrence of trace elements in coal

The standard comparison of relationships of trace element concentrations in coal is based on a comparison of mean values of elemental concentrations. This method is extended by including some functions of covariances among trace element concentrations. In the proposed method, the comparison is based on: the pattern of the mass spectrum of mean values of concentrations; the spectrum of the covariance matrix; the eigenvectors of the covariance matrix; and the order of eigenvectors. The method has been applied to the coal of the Istrian coal basin and the same genesis of the elements calcium, sulphur, iron, titanium and vanadium throughout the considered coal seam has been established.