A CASE STUDY OF DIFFERENT LIMESTONES DURING QUICK LIME AND SLAKED-LIME PRODUCTION

We have examined 5 different limestones in order to study their behavior i) during calcination at different temperatures (900, 1050 and 1200°C for 30 min) and ii) after hydration of quick limes derived to slaked lime. Quick limes calcined at 900°C show the lower reactivity values. This could be related to the low calcination temperature or to the short calcination time of 30 min which was unable to produce enough lime. The samples calcined at temperatures of 1200°C are less reactive compared to the hydrated limes which were prepared by hydration of quick lime calcined at 1050°C, indicating by parameters such as the (CaO+MgO)Lime, the time required to become the temperature maximum and the reactivity rate. These, probably could be due to crystal growth at relative high temperatures

A case study of lime`s behavior during slaking with different set of natural water: implications for industrial water treatment technologies for light brackish waters

Two samples were collected from different quarries from Greece; one sample is characterized as calcitic limestone and the other as dolomitic limestone. The samples were calcined at 1050 0C. We investigated the effective role of the water anions on the reactivity and slaking rate on the basis of laboratory-produced quicklime. The ultimate scope of the present work is to place constraints on the brackish-water treatment processes as potential guidelines, marking the cost-benefits of pointless investments

The potential of phosphorus in clinopyroxene as a geospeedometer: examples from mantle xenoliths

We investigate the potential to use concentrations and zoning patterns of phosphorus (P) in clinopyroxene as indicators of the rates of igneous and metasomatic processes, comparable to recent applications of P in olivine but applicable to more evolved rocks and lower temperatures of crystallization. Few high-P pyroxenes have been previously reported, and none have been analyzed in detail for the mechanism of P enrichment or the implications for mineral growth kinetics. Here, we report the discovery and characteristics of exotic phosphorus-rich secondary clinopyroxene in glassy pockets and veins in composite mantle xenoliths from the Cima Volcanic Field (California, USA) and the Middle Atlas Mountains (Morocco, West Africa). These glass-bearing xenoliths preserve evidence of melt infiltration events and the contrasting behavior of P in their pyroxene crystals constrains the different rates of reaction and extents of equilibration that characterized infiltration in each setting. We report optical petrography and chemical analysis of glasses and minerals for major elements by electron microprobe microanalyzer and trace elements by laser-ablation Inductively Coupled Plasma Mass Spectrometry. The Cima Volcanic Field specimen shows one end-member behavior, with unzoned P-rich clinopyroxene in a melt pocket. We attribute this occurrence to a slow crystallization process that occurred after the melt temperature reached near-equilibrium with the host rock and during which the P concentration in the melt was buffered by apatite saturation. In the Morocco xenolith, by contrast, clinopyroxene exhibits zonation with P increasing all the way to the rim, in contact with the glass. We ascribe this feature to a rapid growth process in which excess P was incorporated into the growing clinopyroxene from a diffusive boundary layer. We demonstrate quantitative agreement between the enrichment of P and other trace elements and their expected diffusion and partitioning behavior during rapid growth. We suggest that P has not been widely reported in clinopyroxene in large part because it has rarely been looked for and that its analysis offers considerable promise as a kinetic indicator both in xenoliths and volcanic rocks

PHOSPHORUS ZONING FROM SECONDARY OLIVINE IN MANTLE XENOLITH FROM MIDDLE ATLAS MOUNTAINS (MOROCCO, AFRICA): IMPLICATIONS FOR CRYSTAL GROWTH KINETICS

Συλλέχθηκαν δείγματα μανδυακών ξενολίθων σε επαφή με βασάλτες από το μάαρ Tafraoute του Μαρόκκου. Διαπιστώθηκε η ύπαρξη φλεβών τήγματος που τέμνουν την πρωτογενή στρωμάτωση και σχιστότητα. Για τον πετρογραφικό και χημικό χαρακτηρισμό των φλεβών τήγματος, εφαρμόστηκαν οι τεχνικές της οπτικής μικροσκοπίας και ηλεκτρονικής μικροανάλυσης. Οι φλέβες αποτελούνται από ύελο και κρυστάλλους ολιβίνη, κλινοπυροξένου, πλαγιοκλάστου, σπινελίου και απατίτη. Ο ολιβίνης είναι πλούσιος στην περιφέρειά του σε φώσφορο ~0,3 %κ.β (εκπεφρασμένο ως P2O5). Correlations between Al and P, as well as experimentally determined partition coefficient for P, point towards non-equilibrium partitioning during rapid crystal growth at the end of crystallization. Βασιζόμενοι σε συντελεστές κατανομής φωσφόρου μεταξύ ολιβίνη και τήγματος, και τη σχέση του αργιλίου με το φώσφορο, 1924 καταλήγουμε σε κατανομή σε συνθήκες μη ισορροπίας κατά τη διάρκεια ταχύτατης ανάπτυξης στο τέλος της κρυστάλλωσηςMantle xenolith samples in contact with basalt flows were collected from the Tafraoute maar in Morocco. Discrete melt veins are present in one xenolith sample, crosscutting primary layering and foliation. We used both optical microscopy and electron microprobe analysis to characterize the glasses and minerals in the melt veins. The melt veins consist of glass and crystals of olivine, clinopyroxene, plagioclase, spinel and apatite. The olivine in the melt veins is quite distinct from the same mineral within the matrix due to its characteristic P-enriched rims (up to 0.3 wt.%). Correlations between Al and P, as well as experimentally determined partition coefficient for P, point towards non-equilibrium partitioning during rapid crystal growth at the end of crystallization

Assessment of the quality of calcination of marbles from Thassos Island using Raman spectroscopy and X-Ray Diffraction

The degree of calcination of a dolomitic and a calcitic marble from Thassos Island, was investigated, by combining both Raman spectroscopy (RS) and X-Ray diffraction (XRD) techniques. The samples were prepared in isometric 2 cm cubes and calcined at three different temperatures, 900, 1050 and 1200 0C for 2 hours in order to produce quick lime. RS was applied at the lime sample's surface and inner (near core) part after gently crushing. XRD was applied on the bulk rock specimens in order to verify the transformation process during heating of the raw material. Quality control of the applied calcination procedure is provided through the hydration of quick lime. The rise in solution temperature suggests the chemical "reactivity" of the produced slaked lime. Raman and XRD results revealed the presence of unburned quantities of calcite and dolomite on samples that were calcined at 900 0C. Furthermore, temperatures of 1050 and 1200 0C have shown comparable mineralogical features signifying evenly the conversion of carbonate minerals to their oxide equivalents, proving the completion of the calcination process. Finally, reactivity tests showed that the highest reactivity value of the produced quicklime, for both marbles is observed at the temperature of 1050 0C