Trend analysis of rainfall and streamflow in "Alto Teles Pires Watershed", northern Brazil.

In this studied were analyzed the streamflow and rainfall of the "Alto Teles Pires Watershed", northern Brazil, in the period from 1977 to 2009.H11G-0934

Method for Improving the Pozzolanic Character of Fly Ash

A method for improving the pozzolanic character of fly ash includes the steps of first hydraulically classifying and then flotation separating the fly ash in order to reduce particle size distribution and remove carbon. The method also includes the steps of spiral concentrating separated coarse particles to recover iron, pyrite and marcasite and screening the fly ash to remove ultra-light carbon and plant debris

Influence of the synthetic procedure on the properties of three Ziegler-Natta catalysts with the same 1,3-diether internal donor

Being the main responsible for the huge production of polyolefins, heterogeneous Ziegler-Natta catalysts are among the most important catalysts in the chemical industry and they have been optimized over the years since their discovery in 1953 crossing many different generations. Lastly, catalysts of the 5th generation are characterized by the introduction in the pre-catalyst of 1,3-diether compounds as internal electron donors, which are stable in the presence of AlR3 activators and do not require the further addition of external donors during the following steps of the catalytic process to control the activity and selectivity. In this work, we synthetized and systematically investigated by a multi-technique approach three Ziegler-Natta catalysts characterized by the same 1,3-diether donor, but differing in the synthesis route. We found that the synthetic route influences the MgCl2 particle size, as well as the properties of the Ti species. In particular, the reprecipitation method brings the smallest MgCl2 particles and the most positive Ti4+ sites in the pre-catalyst, but also the largest amount of accessible Ti3+ sites after TEAl activation. These structural and spectroscopic data correlate pretty well with the kinetic of gas-phase propylene polymerization in very mild conditions

Silica-magnesium-titanium Ziegler-Natta catalysts. Part 1: Structure of the pre-catalyst at a molecular level

In this paper, which is the first part of a more extended work, we elucidate the molecular level structure of a highly active SiO2-supported Ziegler-Natta precatalyst obtained by reacting a dehydroxylated silica and a solution of an organomagnesium compound with TiCl4. The synergetic combination of Ti K-edge and Ti L3-edge X-ray Absorption spectroscopy (XAS) and diffuse reflectance UV–Vis spectroscopies, complemented by Density Functional Theory (DFT) simulations, indicate that small TiCl3 clusters similar to β-TiCl3 coexist with isolated monomeric Ti(IV) species. Ti K-edge Extended X-ray Absorption Fine Structure (EXAFS) Spectroscopy allows the quantification of these two phases and demonstrates that the Ti(IV) sites are 6-fold coordinated (either by six chlorine ligands or by five chlorine and one oxygen ligands), but highly distorted, similar to what is modelled for TiCl4-capped MgCl2 nanoplatelets. Finally, IR spectroscopy suggests that the MgCl2 phase has a molecular character (Far-IR) and that the only accessible Mg2+ sites are uncoordinated cations acting as Lewis acid sites (IR of CO adsorbed at 100 K). Based on these experimental findings, we propose the co-existence in the precatalyst of small TiCl3 clusters and of mixed oxo-chloride magnesium-titanium structures deposited at the silica surface. The evolution of the precatalyst in the presence of the activator and of the monomer is discussed in the second part of this work

POC-scale testing of an advanced fine coal dewatering equipment/technique: Quarterly technical progress report No. 9, October 1996--December 1996

The advanced fine-coal cleaning techniques such as column flotation, recovers a low-ash ultra-fine size clean-coal product. However, economical dewatering of the clean coal product to less than 20 percent moisture using conventional technology is difficult. This research program objective is to evaluate a novel coal surface modification technique developed at the University of Kentucky Center for Applied Energy Research in conjunction with conventional and advanced dewatering technique at a pilot scale at the Powell Mountain Coal Company`s Mayflower preparation plant located in St. Charles, VA. During this quarter in the laboratory dewatering studies were conducted using copper and aluminum ions showed that for the low sulfur clean coal slurry addition of 0.1 Kg/t of copper ions was effective in lowering the filter cake moisture from 29 percent to 26.3 percent. Addition of 0.3 Kg/t of aluminum ions provided filter cake with 28 percent moisture. For the high sulfur clean coal slurry 0.5 Kg/t of copper and 0.1 Kg/t of aluminum ions reduced cake moisture from 30.5 percent to 28 percent respectively. Combined addition of anionic (10 g/t) and cationic (10 g/t) flocculants was effective in providing a filter cake with 29.8 percent moisture. Addition of flocculants was not effective in centrifuge dewatering. In pilot scale screen bowl centrifuge dewatering studies it was found that the clean coal slurry feed rate of 30 gpm was optimum to the centrifuge, which provided 65 percent solids capture. Addition of anionic or cationic flocculants was not effective in lowering of filter cake moisture, which remained close to 30 percent for both clean coal slurries

Inherited Ocean-Continent Transition zones in deeply subducted terranes: Insights from Alpine Corsica

In the Schistes Lustrés of Alpine Corsica (France) serpentinized mantle rocks are associated with continental basement and meta-volcanic/-sedimentary cover rocks. The relationships among these different lithologies are especially well exposed in the Monte San Petrone unit, where Alpine metamorphism reached lawsonite-eclogite conditions. The contact between serpentinites and slivers of continental basement, relatively flat-lying over several kilometers, is characterized by evidence of cataclastic deformation pre-dating Alpine High-Pressure ductile fabrics. The serpentinite/continental basement pair is stratigraphically overlain by metasediments with a typical Jurassic-Cretaceous supra-ophiolitic lithostratigraphy, with metaradiolarites passing upward to marbles and calcschists. Noticeably, no evidence of cataclastic deformation is found in metasediments. These observations indicate that the lithostratigraphy of the Monte San Petrone unit was established during a pre-Alpine polyphase evolution, which culminated in extensive brittle deformation along a flat-lying detachment fault prior to the deposition of Jurassic sediments. We suggest that the inferred Mesozoic extensional tectonics were related to the opening of the Western Tethys. The Mesozoic architecture of the Monte San Petrone area, which is typical of an Ocean-Continent Transition (OCT) zone, was preserved despite Alpine deformation and metamorphism, when the different lithologies (i.e. meta-ophiolites, continent-derived rocks and metasediments) underwent a common metamorphic evolution, culminating at T=490-550. °C and P=2.2-2.6. GPa. Similar tectono-stratigraphic associations are observed in other high-pressure terranes of Alpine Corsica, suggesting that inherited OCT-type domains may be common in Alpine-type orogens. © 2011 Elsevier B.V