Prediction of Acid Mine Drainage: Importance of Mineralogy and the Test Protocols for Static and Kinetic Tests

Static tests, which compare the acid-generating potential and acid-neutralizing potential for a given mine waste (tailings or waste rocks), are characterized by a wide uncertainty zone in which it is impossible to accurately predict the acid-generating potential (AGP). Then, to better assess long-term AGP, kinetic tests are usually performed to provide more information about the reaction rates of the acid-generating and acid-neutralizing minerals. The present work compares the classic Sobek static test with three mineralogical static tests to assess the importance of sample mineralogy in acid mine drainage (AMD) prediction. We also investigated how experimental procedures related to static tests can influence prediction results. We used three synthetic tailings samples made by mixing well-characterized pure minerals in calibrated proportions. Although basically different in their principles and procedures, the modified Sobek and mineralogical static tests gave similar results. These AGP predictions were then validated by the use of a kinetic test. The kinetic test protocol was also modified in this study and the results obtained correlated well with the static test results, in contrast to the standard kinetic test protocol. The present work highlights the limitations of static and kinetic test procedures, and provides recommendations for a better use of these tests for more reliable AMD prediction.     

A low-complexity audio fingerprinting technique for embedded applications

Multimedia Tools and Applications - This paper proposes a new optimized audio-based fingerprinting technology for embedded applications. The target use case is related to TV content synchronization...     

LEKIDs Developments for mm-Wave Astronomy

Microwave Kinetic Inductance Detectors (MKIDs) have recently drawn the attention of the low-temperature detectors community. Easy fabrication, high sensitivity, small time constants and most notably the intrinsic capability to frequency multiplexing open new possibilities to applications that need very large array sizes and/or high speed read-out. Lumped Element Kinetic Inductance Detectors (LEKIDs) designed and fabricated in our collaboration have already shown good on sky performances, but new developments are needed for future multi-thousands-pixels instruments. In this contribution we present such ongoing developments: a new LEKIDs design, optimized to be dual polarization sensitive; use of new materials such as TiN in order to reach better signal to noise ratios; new solutions to minimize the cross-talk between pixels in order to achieve a better control of the resonance positions in frequency space. We discuss present lab measurements of the optical performances and recent improvements of the read-out electronics.     

Pairwise testing for software product lines: comparison of two approaches

Software Product Lines (SPL) are difficult to validate due to combinatorics induced by variability, which in turn leads to combinatorial explosion of the number of derivable products. Exhaustive testing in such a large products space is hardly feasible. Hence, one possible option is to test SPLs by generating test configurations that cover all possible t feature interactions (t-wise). It dramatically reduces the number of test products while ensuring reasonable SPL coverage. In this paper, we report our experience on applying t-wise techniques for SPL with two independent toolsets developed by the authors. One focuses on generality and splits the generation problem according to strategies. The other emphasizes providing efficient generation. To evaluate the respective merits of the approaches, measures such as the number of generated test configurations and the similarity between them are provided. By applying these measures, we were able to derive useful insights for pairwise and t-wise testing of product lines.     

Deterioration of Concrete by the Oxidation of Sulphide Minerals in the Aggregate

Cases of degradation of concrete associated to iron sulphides in aggregates were recently recognized in the Trois-Rivi6res area, Canada. The aggregate used to produce concrete was an anorthositic gabbro containing various proportions of pyrite, pyrrhotite, chalcopyrite and pentlandite. Quantitative microanalysis on sulphide minerals show that pyrrhotite contains small amount of Ni, Co, Cu and As substituting for Fe in the mineral structure. Considering element substitution, x value in the chemical formula （Fe~.xS） was calculated to 0.099 in the pyrrhotite studied. Petrographic examination of damaged concretes showed the presence of oxidized pyrrhotite. The observation of polished samples shows, in several cases, that the pyrite is intact while the pyrrhotite presents evident signs of oxidation. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste and provokes the formation of gypsum and ettringite. These minerals were observed by SEM-EDS （scanning electron microscope/energy dispersive x-ray spectrometer） and their precipitation causes a volume increase that creates expansion and cracking of the concrete.     

两类典型碱活性岩石试体在碱溶液中的膨胀行为

为确定以Spratt硅质灰岩(SL岩石)和Pittsburg泥质白云质灰岩(PL岩石)为代表的两类典型碱活性岩石试体在碱性环境中的膨胀来源和发展评定岩石碱活性的方法,研究了不同条件下SL和PL岩石在砂浆和混凝土中的膨胀行为.研究结果表明:SL岩石在砂浆和混凝土中均呈高ASR膨胀性,尽管其中的少量白云石可发生去白云石化反应;决定PL岩石高膨胀性的机制是ACR,与传统的ASR有本质不同,尽管其中含有的少量微晶石英可参与与碱的反应并可能对岩石的膨胀有一定贡献.采用能保持岩石微观结构构造特征的颗粒尺寸是正确评估PL岩石碱活性的关键.利用ASR和ACR对粉煤灰等混合材及含锂化合物的不同响应,特别是LiOH的抑制ASR膨胀和引发ACR膨胀的双重效应,在实验室可以快速区别同时含有白云石和石英的灰岩类集料的活性来源.     

Experimental investigation of solid particles flow in a conical spouted bed using radioactive particle tracking

Solid particles flow in a conical spouted bed is characterized by radioactive particle tracking. The influence of operating conditions on key parameters of this flow is evaluated and discussed: the morphology of the solid bed is not strongly influenced by the forces exerted by the gas on the solid particles, but rather by geometrical considerations; the particles spend approximately 8% of their time in the spout in all experiments; it is the force exerted on the solid particles by the gas that directly controls the volumetric flow rate between adjacent regions, and not the amount of particles in the bed; as U/U_ms increases, the volume of solid particles in the annulus decreases, the volume of solid particles in the fountain increases and the volume of solid particles in the spout remains constant. Correlations to predict key flow parameters as functions of operating conditions are also established and discussed. © 2015 American Institute of Chemical Engineers AIChE J, 62: 26–37, 2016