A New Application of Solvent Extraction to Separate Copper from Extreme Acid Mine Drainage Producing Solutions for Electrochemical and Biological Recovery Processes

Over the last decade, AMD waters have gained more attention as a potential source of metals due to the emerging need to recover or recycle metals from secondary resources. Metals recovery supports sustainability and the development of a circular economy with benefits for resource conservation and the environment. In this study, five extractants (Acorga M5640, LIX 54, LIX 622, LIX 622 N, and LIX 864) diluted (15% (v/v)) in Shell GTL with 2.5% (v/v) octanol were compared and evaluated for Cu recovery from an extreme AMD sample (5.3?±?0.3 g/L Cu) collected at the inactive São Domingos Mine in the Iberian Pyrite Belt of Portugal. Of the five extractants, Acorga M5640 showed the best selective efficiency. Further tests showed that 30% (v/v) of this extractant was able to selectively extract ≈ 96.0% of the Cu from the AMD in one extraction step and all of the remaining Cu (to below detection) in three steps. Among the different stripping agents tested, 2 M sulfuric acid was the most efficient, with ≈ 99% of the Cu stripped, and the recyclability of the organic phase was confirmed in five successive cycles of extraction and stripping. Furthermore, contact time tests revealed that the extraction kinetics allows the transfer of ≈ 97% of the Cu in 15 min, and aqueous to organic phase ratios tests demonstrated a maximum loading capacity of ≈ 16 g/L Cu in the organic phase. Raising the concentration of Cu in the stripping solution (2 M sulfuric acid) to ≈ 46 g/L through successive striping steps showed the potential to recover elemental Cu using traditional electrowinning. Finally, a biological approach for Cu recovery from the stripping solution was evaluated by adding the supernatant of a sulfate-reducing bacteria culture to make different molar ratios of biogenic sulfide to copper; ratios over 1.75 resulted in precipitation of more than 95% of the Cu as covellite nanoparticles.

Graphical Abstract

     

3D modeling of uranium-bearing solution-collapse breccias in Proterozoic sandstones (Athabasca Basin,Canada)—Metallogenic interpretations

Unconformity-related uranium deposits are the highest grade, large tonnage uranium resources in the world. In the Athabasca Basin (northern Saskatchewan, Canada), which is the premier host for unconformity-type deposits, the ore deposits are frequently hosted and surrounded by breccias in sandstone. The significance of these breccias and their relation to mineralization are of major importance for the genesis of these high-grade deposits. Therefore, a modeling study, integrating results from structural geology and petrology, was performed with the gOcad 3D modeling software, in order to decipher geometrical and geological relationships between breccias, faults and mineralization zones. Mineralized bodies and the sudoite–dravite breccia bodies display strong spatial correlations. They appear to be controlled by reverse shear zones cross-cutting the unconformity and containing graphite in the basement. Geochemical computations evidenced that volumetric water–rock ratios up to 10,000 could be obtained in these breccia bodies for volume losses of up to 90%. Assuming reasonable values for quartz saturation, hydraulic conductivity and connected porosity, the minimal fluid volume and the time duration necessary to generate the sudoite–dravite breccia bodies were estimated at ca. 2 km³ and ca. 1 Myr, respectively. The comparison of these results with literature data suggests that the formation of sudoite–dravite breccia and mineralization could have been coeval. It may be proposed that within the space created by the quartz dissolution in the breccia body, a mixing between basement and basinal fluids could have induced U deposition and allowed the development of high-grade mineralization. The first-order uranium solubility that this coeval formation would imply is consistent with literature data, which suggests that this conceptual model is reasonable.     

Image-based gating of intravascular ultrasound pullback sequences

Intravascularultrasound (IVUS) sequences recorded in vivo are subject to a wide array of motion artifacts as the majority of these studies are performed within the coronary arteries of a beating heart. To eliminate these artifacts, an electrocardiogram (ECG) signal is typically used to gate (collect) those frames recorded at the points in time associated with a particular fraction of the cardiac cycle. However, this technique may be suboptimal for a number of reasons, among which is the difficulty of determining the optimal fraction at which to gate. This value is generally nonobvious. To circumvent this problem, we introduce a frame-gating method for IVUS pullbacks that mimics ECG (i.e., in the sense that it selects only one frame per cardiac cycle), but will automatically choose the fraction of the cycle that renders the most stable gated frame set. Stability here is gauged by measuring interframe similarity. Our method operates exclusively on the imagery data and does not require ECG or any form of image segmentation or other high-level image analysis. To validate our algorithm, we compare its behavior versus true ECG gating.     

Multi‐element characterisation of carob,fig and almond liqueurs by MP‐AES

Carob pod, fig and almond liqueurs are produced in various Mediterranean regions. This work reports the mineral content of these traditional beverages and evaluates the influence of the raw material. Twenty‐five fruit liqueurs from 16 producers were analysed. A simple open‐vessel sample mineralization by wet digestion using nitric acid–hydrogen peroxide (1:1) was used before spectrometric analysis. Nine essential elements (Cu, Ca, Mg, Na, K, Fe, Zn, Mn and P) and two non‐essentials (Cd and Pb) were quantified by microwave plasma–atomic emission spectrometry (MP‐AES). Carob liqueur presented the broader profile of minerals and was the only fruit liqueur containing iron (72.7% of samples), phosphorous, manganese and low levels of lead (in two of the 11 samples). Conversely, almond liqueurs contained the lowest mineral content with only five elements detected. Fruit liqueurs showed variability in mineral content even within the same liqueur, presumably as a consequence of the different manufacturing processes. Despite this variability, application of principal component analysis to essential mineral concentrations (K, Na, Ca, Mg, Mn, Fe and Zn) resulted in satisfactory classification (PC1 and PC2 accounting for 78.5% of the total variance) of the Portuguese liqueurs evaluated. Copyright © 2018 The Institute of Brewing & Distilling     

Shape-driven segmentation of the arterial wall in intravascular ultrasound images

Segmentation of arterial wall boundaries from intravascular images is an important problem for many applications in the study of plaque characteristics, mechanical properties of the arterial wall, its 3-D reconstruction, and its measurements such as lumen size, lumen radius, and wall radius. We present a shape-driven approach to segmentation of the arterial wall from intravascular ultrasound images in the rectangular domain. In a properly built shape space using training data, we constrain the lumen and media-adventitia contours to a smooth, closed geometry, which increases the segmentation quality without any tradeoff with a regularizer term. In addition to a shape prior, we utilize an intensity prior through a nonparametric probability-density-based image energy, with global image measurements rather than pointwise measurements used in previous methods. Furthermore, a detection step is included to address the challenges introduced to the segmentation process by side branches and calcifications. All these features greatly enhance our segmentation method. The tests of our algorithm on a large dataset demonstrate the effectiveness of our approach.     

Lessons from the organization of a proficiency testing program in food microbiology by interlaboratory comparison: analytical methods in use, impact of methods on bacterial counts and measurement uncertainty of bacterial counts

The proficiency testing program in food microbiology RAEMA (Réseau d'Analyses et d'Echanges en Microbiologie des Aliments), created in 1988, currently includes 450 participating laboratories. This interlaboratory comparison establishes proficiency in detection of Salmonella and Listeria monocytogenes, as well as enumeration of aerobic micro-organisms, Enterobacteriaceae, coliforms, beta-glucuronidase-positive Escherichia coli, anaerobic sulfito-reducing bacteria, Clostridium perfringens, coagulase-positive staphylococci, and L. monocytogenes. Twice a year, five units samples are sent to participants to assess their precision and trueness for enumeration and detection of micro-organisms. Most of participating laboratories use standard or validated alternative methods, they were 50-70% in 1994 and, for 5 years, they are 95%. An increasing use of alternative methods was also observed. This phenomenon is all the more significant as standard methods are laborious and time consuming; thus, 50% of the laboratories use alternative methods for the detection of Salmonella and L. monocytogenes. More and more laboratories use ready-to-use media and although the percentage is variable according to the microflora, we can consider that, today, 50-60% of the laboratories participating to the proficiency program only use ready-to-use media. The internal quality assurance programs lead also to an increasing use of media quality controls. The impact of analytical methods on bacterial counts was assessed by grouping together the results obtained by participating laboratories during the 10 last testing schemes from 1999 to 2003. The identified significant factors influencing enumeration results are variable from one microflora to another. Some of them significantly influence many microflora: the plating method (spiral plating or not) is influential for aerobic micro-organisms, Enterobacteriaceae, coliforms, and staphylococci, the type of culture medium and the medium manufacturer is influential for aerobic micro-organisms, Enterobacteriaceae, coliforms, E. coli, anaerobic sulfito-reducing bacteria, staphylococci, and L. monocytogenes. Others are specific of some micro-organisms: the resuscitation broth for L. monocytogenes, the mode of medium preparation for staphylococci and the incubation temperature for C. perfringens. These effects lead generally to small differences of about 0.1 log10 cfu g(-1), except for the enumeration of anaerobic sulfito-reducing bacteria, where the difference reaches 0.7 log10 cfu g(-1). These results, although difficult to extrapolate to all actual situations, which associate numerous food constituents and physiological states of bacteria to detect or numerate, allow nevertheless the quantification of interlaboratory variations linked to the methods in use. The analysis of bacterial counts obtained by the laboratories participating to the RAEMA proficiency testing program allowed also to validate a formula to calculate the repeatability of bacterial counts and to estimate the between-laboratory uncertainties for the majority of micro-organisms enumerated in food microbiology. The repeatability uncertainty is only indirectly affected by the method in use but depends essentially on the number of counted colonies. On the other hand, the between-laboratory uncertainty varies with the enumeration method in use, this variability is relatively small for the enumerations calling for methods without colony confirmation, i.e. for the enumeration of aerobic micro-organisms, Enterobacteriaceae, 'total' and thermotolerant coliforms, beta-glucuronidase-positive E. coli and coagulase-positive staphylococci with the technique using the rabbit-plasma fibrinogen agar. For these methods, the average between-laboratory standard deviation is 0.17 log10 cfu g(-1). The between-laboratory uncertainty is, on the contrary, larger for more complex techniques. For the enumeration of coagulase-positive staphylococci with the Baird-Parker agar, the between-laboratory standard deviation is equal to 0.23 log10 cfu g(-1), it is equal to 0.28 log10 cfu g(-1) for the enumeration of L. monocytogenes, to 0.34 log10 cfu g(-1) for the enumeration of C. perfringens, and to 0.47 log10 cfu g(-1) for the enumeration of anaerobic sulfito-reducing bacteria.     

Species identification of meat products by ELISA

ELISA methods used in this study are proved to detect low contents of animal species (pork, beef, sheep and poultry), even in highly processed foods. They present the advantages of being robust, cheap and easy to perform. Nevertheless, F factors, determining the threshold values of the test, need to be validated for each species.