Sequestration of CO2 in magnesium silicates, in Western Macedonia, Greece

Carbonation of magnesium seems to be an interesting option for long term storage of captured CO₂. This paper provides an approach to sequestration of carbon dioxide in magnesium silicates using ultramafic rocks from the mountain of Vourinos, in Western Macedonia, Greece. For the experimental procedure five samples were used, consisted of dunite, hartzburgite and pyroxenite. The carbonation method chosen is the aqueous scheme. The results showed low (only about 10% of the stoichiometrically possible amount) transformation into magnesium carbonates for the majority of the samples. Insufficient reaction time, the particle size, or improper choice of reaction conditions are may be some of the reasons for the small amounts of carbonation observed. Further studies are needed in order to identify the various issues that were responsible.     

Progressive Failure of Slopes: Stochastic Simulation Based on Transition Probabilities and Markov Chains

Geotechnical and Geological Engineering - A reliability analysis framework for the stochastic simulation of slope progressive failure is proposed in the current work. Progressive failure is...     

Analysis of Faults' Effect on the Stability of Surface Lignite Mining Areas Using the Distinct Element Method

Geotechnical and Geological Engineering - Mining operations can drastically affect the stability of nearby areas. A representative case for this has been the Mavropigi mine, a part of an open-pit...     

Numerical Slope Stability Analysis of Deep Excavations Under Rainfall Infiltration

Geotechnical and Geological Engineering - Rainfall leads to the deterioration of slope stability conditions, while intense rainfall has been commonly associated with landslides on natural or...     

The petrology of greek brown coals

Results are given in the petrography of Greek coals collected from most of the major coal-bearing basins in Greece.Rank was determined by measuring reflectances on the maceral varieties eu-ulminite A and eu-ulminite B and on the maceral textinite. Reflectances obtained from these components indicate a coalification stage of brown coal for all samples. Within this group of samples there is, however, a fairly wide scatter of reflectance values indicating for some of them the transition zone from peat to brown coal and for others a coalification stage close to the transition into bituminous coals. Reflectances obtained from eu-ulminite A and eu-ulminite B were found to correlate well with chemical rank parameters such as volatile matter and calorific value.Composition was determined by maceral analysis. The coals are in general characterized by low amounts of macerals of the inertinite group, low to intermediate amounts of macerals of the liptinite group and high amounts of macerals of the huminite group. Within the latter group densinite, attrinite, eu-ulminite and textinite make up the bulk of the samples.Typical macerals observed in the coals are illustrated by two black and white and three colour plates.Cluster analysis based on maceral distribution, mineral matter and reflectance indicates that the samples studied can be divided into three major groups. The first one is dominated by eu-ulminite and densinite with relatively high reflectances. The second is dominated by attrinite, textinite and texto-ulminite with somewhat lower reflectances. The third is represented by a single sample in which textinite and resinite are the most abundant macerals. This sample also has the lowest reflectance.     

Geochemical controls on leaching of lignite-fired combustion by-products from Greece

The mobility of inorganic pollutants is of key concern for a range of industrial and engineering applications of fly ash produced during the combustion of lignite in power generation. This paper investigates the role that the geochemical features of lignite, the ash composition and the partitioning of elements during combustion play in determining leaching properties of lignite fired by-products. The work is based on surveys on three lignite-fired power plants in Greece. Calcium-rich ashes show a high abatement potential for SO₂ and other gaseous pollutants. For most elements, the concentrations in the parent lignite and the ashes follow the same trend. Relative enrichments in Cd, Co, Cr, Cu, Mo, Ni, Pb, U, V, W, Zn fingerprint the regional and local geological settings of the lignite basins. The total and leachable concentrations of highly volatile elements are strongly influenced by the interaction with ubiquitous free lime. A broad array of elements is highly insoluble in alkaline ash, while a few oxyanionic-forming elements display substantial mobility. Their mode of occurrence in the parent lignite plays a primary role in the leaching of combustion ashes. The outcomes of this study may assist in addressing the impact of co-firing high ash or high Ca alternative fuels on the leaching properties of combustion by-products.