Peter Andráš

Raman spectra of oriented and non-oriented Cu hydroxy-phosphate minerals: Libethenite, cornetite, pseudomalachite, reichenbachite and ludjibaite

Oriented cornetite [Cu3PO4(OH)3], libethenite [Cu2PO4(OH)] and pseudomalachite [Cu5(PO4)2(OH)4] and non-oriented reichenbachite [Cu5(PO4)2(OH)4] and ludjibaite [Cu5(PO4)2(OH)4] minerals from Ľubietová and Špania Dolina dump fields, Banská Bystrica, Slovakia were examined by polarized Raman spectroscopy. The examined minerals display the characteristic vibrational modes of PO4 and OH groups and further lattice modes. The PO4 stretching and bending vibrations of the investigated minerals occur between 1150 and 900 cm(-1) and between 700 and 350 cm(-1), respectively. On the other hand, the hydroxyl group stretching and bending modes appear above 3350 cm(-1) and between 900 and 700 cm(-1), respectively. The lattice vibrations occur below 350 cm(-1). The different bond distances of the PO4 groups readily explain the shift of the bands to higher or lower wavenumbers among the studied Cu hydroxy-phosphate minerals.

Investigations of the Fe sulfosalts berthierite, garavellite, arsenopyrite and gudmundite by Raman spectroscopy

Abstract Arsenopyrite (FeAsS), gudmundite (FeSbS) and the rarer Fe sulfosalts berthierite (FeSb2S4) and garavellite (FeSbBiS4), were investigated by Raman spectroscopy. Whereas (Sb,Bi)S3 pyramids are responsible for the Raman spectra of berthierite and garavellite, the spectra of gudmundite and arsenopyrite arise from the stretching and bending modes of (Sb,As)S units. Internal vibrations for berthierite and garavellite occur between 400 and 50 cm-1, and those of the gudmundite and arsenopyrite between 500 and 100 cm-1. The longer bond distances of the SbS3 groups readily explain the lower frequencies for berthierite in comparison with garavellite. Similarly, the greater mass and the longer bond distances of the Sb-S units also explain the lower frequencies observed for gudmundite relative to arsenopyrite.

The interaction of heavy metals and metalloids in the soil–plant system in the São Domingos mining area (Iberian Pyrite Belt, Portugal)

São Domingos belongs among the most important historic Iberian Pyrite Belt Cu mines. The anthrosoil is contaminated by a very high content of heavy metals and metalloids. The study was focused on evaluating the interaction of some chemical elements (Ca, Mg, Fe, Mn, Cu, Pb, Zn, Ag, Cd, Ni, Co, As, Sb) in the system soil vs. five autochthonous dominant plant species: Pinus pinaster Aiton, Quercus rotundifolia Lam., Agrostis sp., Juncus conglomeratus L. and Juncus effusus L. The plants are heavily contaminated by Cu, Pb, As and Zn. The bioconcentration factor proved that they exhibit features of metal tolerant excluders. The trees are accumulators of Ag, whereas the graminoids are hyper-accumulators of Ag and Juncus effusus of Co. The translocation factor confirmed that the selected elements are immobilised in the roots except for Mn and Zn in Pinus pinaster and Mn in Quercus rotundifolia and Juncus conglomeratus. The bioaccumulation of Mn, Zn and Cu at low pH increases. The increased content of Ca and Mg in the soil inhibits, in the case of some metals and metalloids, their intake to plants. Although the studied plants, despite their fitness and vitality at the contaminated sites, are not suitable for phytoextraction (except Co and Ag), they can be used for phytostabilisation at the mining habitats.

The determination of the Sb/As content in natural tetrahedrite–tennantite and bournonite–seligmannite solid solution series by Raman spectroscopy

Abstract Natural samples containing tetrahedrite-tennantite, bournonite-seligmannite and geocronite-jordanite from the Coranda-Hondol ore deposit, Romania, were investigated by Raman spectroscopy to determine its capability to provide estimates of solid solutions in three common and widespread sulfosalt mineral series. Raman measurements were performed on extended solid solution series (Td1 to Td97, Bnn25 to Bnn93 and Gcn24 to Gcn67, apfu). The tetrahedrite-tennantite and bournonite-seligmannite solid solution series show strong correlations between spectroscopic parameters ( position, relative intensity and shape of the Raman bands) and the Sb/(Sb+As) content ratio, while Raman spectra of geocronite-jordanite shows no evolution of Raman bands. In order to simplify the method used to estimate the Sb/(Sb+As) content ratio in tetrahedrite-tennantite and bournonite-seligmannite series, several linear equations of the first-order polynomial fit were obtained. The results are in good agreement with electron microprobe data. Moreover, a computer program was developed as an analytical tool for a fast and accurate determination of Sb/(Sb+As) content ratio by at least one spectroscopic parameter. These results indicate that Raman spectroscopy can provide direct information on the composition and structure of the tetrahedrite-tennantite and bournonite- seligmannite series.

Thermal Treatment of Wood for Mitigating of Climate Change

Among individual techniques of wood treatment, there are highly significant differences in the greenhouse gas balance. Greenhouse gases have, according to the currently adopted global convention, a major impact on global warming and climate change. Nevertheless, there are also sceptical opinions on the scientific basis of such concept. As well as the natural processes of tree growth and the end of their life cycle, the wood processing technologies also affect the balance of greenhouse gases on Earth. The current natural forest without human intervention does not have to reduce greenhouse gas emissions definitely, but can also be the source of their emissions. Also, technological, particularly thermal, processes have different contribution to the production of greenhouse gases. The submitted paper presents the context of warming and cooling of the Earth during its development with a concentration of carbon dioxide in the atmosphere. Further, the indicative greenhouse gas balance, respectively, CO2 generated at thermal wood processing processes, are analysed.

ACIDIFICATION PROCESS IN THE AREA OF THE ABANDONED ĽUBIETOVÁ - PODLIPA CU-DEPOSIT, SLOVAKIA PROCES ACIDIFIKÁCIE V OBLASTI OPUSTENÉHO CU-LOŽISKA ĽUBIETOVÁ - PODLIPA, SLOVENSKO

Abstract Acidity in surroundings of the abandoned Ľubietová-Podlipa Cu-deposit depends predominantly on the geochemical behaviour (weathering) of particular minerals (mainly pyrite). The article presents the results of measurements of basic physicochemical parameters - pH and Eh in technogenic sediments and in surface and drainage water of a dump-field. Although the dump material shows a significant amount of mobility-able metals and thus also a potential to form acidity, a massive AMD formation in future is not probable. Abstrakt Acidita v okolí opusteného Cu-ložiska Ľubietová - Podlipa závisí predovšetkým od geochemického správania sa (zvetrávania) niektorých minerálov (hlavne pyritu). V článku sú prezentované výsledky meraní základných fyzikálno-chemických parametrov - pH a Eh v technogénnych sedimentoch a v povrchovej a drenážnej vode haldového poľa. Haldový materiál síce stále vykazuje značné množstvo mobilizovateľných kovov a teda aj istý potenciál tvoriť kyslosť, podľa výsledkov výpočtu rizika, k masívnejšej tvorbe AMD nebude v budúcnosti pravdepodobne dochádzať.