Detailed Characterization Tests Research Articles

Vanadyumun Silis Kumundan Liç Yöntemi ile Ekstraksiyonunda Organik Asitlerin Performansının İncelenmesi

In this study, performance of organic acids in the extraction of vanadium from silica sand, a potential vanadium source, were investigated by leaching method. Silica sand samples used in this study was obtained from a silica sand beneficiation plant operating in Istanbul, Turkey. In the context of experimental studies, detailed characterization tests and leaching tests with organic and inorganic acids were performed on the representative samples obtained from the desliming unit of the plant, and the optimum extraction conditions for vanadium were determined. The obtained results showed that the best result for vanadium extraction was obtained with hydrofluoric acid. The extraction efficiency of vanadium was found to be 76% under optimal leaching conditions of 2 h of leaching time, 800 kg/ton of HF amount and 40oC pulp temperature. On the other hand, the best results among the organic acids were obtained with oxalic acid. The extraction efficiency of vanadium was found to be 50% under optimal leaching conditions of 2 h of leaching time, 200 kg/ton of oxalic acid amount and 40oC pulp temperature.

Hydraulic and Mass Transfer Performances of a Commercial Hybrid Packing: The RSP200X-Key Modelling Parameters for Gas Treatment Applications

The use of the last generation of Raschig’s structured packings, Raschig SuperPack (RSP) has been investigated for scrubbing columns operating at high liquid loads, for their potential to increase capacity while maintaining mass transfer efficiencies at high levels. IFPEN has measured pressure drops, flooding limits, liquid and gas side mass transfer coefficients and interfacial areas for the RSP 200X. Flooding limits were in agreement with literature, however at high liquid loads and for tested X-Style RSP they were 30-40% lower than those calculated with the Winsorp Software. This indicates that extrapolation of flooding models should be used with caution to size column diameters for fluid systems and liquid loads that differ from those from which these models were derived. With the support of the present results a modified version of Winsorp has been elaborated for high liquid loads and X-Style RSP. RSP 200X develops a high interfacial area, close to the one of a standard 250 m2/m3 structured packing. One important difference however has been noted about the impact of the gas flowrate on the interfacial area. While for standard packings the gas flow rate is often considered to have only a small effect on area when operating below the loading point, the effect measured on RSP200X is significant and of the same order as for liquid load. Measurements of kLae further confirm that these latest generations of packings show different trends when compared to standard structured packings. Detailed characterization tests are therefore highly recommended to estimate the performances of these packings in terms of hydraulics and mass transfer properties. In some distant future, it is believed that CFD calculations (gas and gas/liquid) will help to better understand and model such phenomena.

The PreAmplifier ShAper for the ALICE TPC detector

In this paper the PreAmplifier ShAper (PASA) for the Time Projection Chamber (TPC) of the ALICE experiment at LHC is presented. The ALICE TPC PASA is an ASIC that integrates 16 identical channels, each consisting of Charge Sensitive Amplifiers (CSA) followed by a Pole-Zero network, self-adaptive bias network, two second-order bridged-T filters, two non-inverting level shifters and a start-up circuit. The circuit is optimized for a detector capacitance of 18–25pF. For an input capacitance of 25pF, the PASA features a conversion gain of 12.74mV/fC, a peaking time of 160ns, a FWHM of 190ns, a power consumption of 11.65mW/ch and an equivalent noise charge of 244e+17e/pF. The circuit recovers smoothly to the baseline in about 600ns. An integral non-linearity of 0.19% with an output swing of about 2.1V is also achieved. The total area of the chip is 18mm2 and is implemented in AMS's C35B3C1 0.35μm CMOS technology. Detailed characterization tests were performed on about 48000 PASA circuits before mounting them on the ALICE TPC front-end cards. After more than two years of operation of the ALICE TPC with p–p and Pb–Pb collisions, the PASA has demonstrated to fulfill all requirements.