The behavior of tellurium during copper ore processing at the American Smelting and Refining Company (Tucson, AZ)

Thesis (M.S.) University of Alaska Fairbanks, 2016Essentially all tellurium (Te), an element used in solar panels and other high technology devices, is recovered as a byproduct of copper mining. Recent increases in demand have sparked questions of long-term supplies of Te (crustal abundance ~3 μg∙kg-1). As part of a larger study investigating Te resources, this project examines the behavior of Te during Cu ore mining, smelting, and refining at the American Smelting and Refining Company (Tucson, AZ) as a first step toward optimizing Te recovery. Mass balance calculations estimate that only 4 ± 1% of the Te in the ore reports to the Cu anodes, while 60 ± 30%, 0.8 ± 0.2% and 5.8 ± 0.4% is lost in the tailings, slag, and dust, respectively. The uncertainties reported are the standard deviation of analytical measurements, but due to heterogeneity of Te distribution in the ore, the actual uncertainty is likely higher. Microprobe data shows that Te in the concentrate is mainly present as telluride minerals, but substitution into sulfides most likely also occurs. X-ray fluorescence (XRF) mapping showed that Te is collocated with S in the raw anode slimes, pressed anode slimes, and doré furnace soda slag. X-ray absorption spectroscopy (XAS) was used to examine Te speciation in anode slimes. It was found that Te oxidizes during the Cu ore smelting process, with 44% Te4+ in the flash furnace SO₂ filter. Te also showed 32% Te4+ in the raw and pressed anode slimes. The doré furnace soda slag and dust filter showed the most oxidation of Te at 57% Te4+ and 60% Te6+ respectively. These results indicate several points in the extraction process that could be examined further to determine if additional Te might be recovered from the overall process.Chapter 1 Introduction -- 1.1. What is Tellurium? -- 1.2. Tellurium End Uses and Market -- 1.3. Global Supply of Tellurium -- 1.4. Tellurium Scarcity and Criticality -- 1.5. Current Copper Extraction Process -- 1.5.1. Copper Mining -- 1.5.2. Copper Smelting -- 1.5.3. Copper Refining -- 1.6. Tellurium Byproduct Recovery -- 1.6.1. Mineralogy of Tellurium in Ore Deposits -- 1.6.2. Behavior of Tellurium during Copper Concentration -- 1.6.3. Behavior and Mineralogy of Tellurium in Copper Anodes and Anode Slimes -- 1.6.4. Extraction of Tellurium as a Copper Byproduct -- 1.7. Research Objectives -- Chapter 2. Site Description -- 2.1. The Mines -- 2.2. The Smelter -- 2.3. The Refinery -- Chapter 3. Methods -- 3.1. Sample and Standard Collection, Preparation, and Preservation -- 3.2. Elemental Analysis -- 3.2.1. Inductively Coupled Plasma Mass Spectrometry -- 3.2.1.1. Method Development of Sodium Peroxide Sinter -- 3.2.1.2. Sample Preparation for ICP-MS -- 3.2.1.3. ICP-MS Elemental Analysis -- 3.2.2. Wavelength Dispersive X-Ray Fluorescence -- 3.2.2.1. Sample Preparation and Analysis of WD-XRF -- 3.3. Mass Balance Calculations -- 3.4. X-Ray Absorption Spectroscopy -- 3.4.1. Bulk S XAS -- 3.4.1.1. Bulk S XAS Collection -- 3.4.1.2. S XAS Data Analysis -- 3.4.1.3. S Linear Combination Fitting -- 3.4.2. Bulk Te XAS -- 3.4.2.1. Bulk Te XAS Collection -- 3.4.2.2. Te XAS Data Analysis -- 3.4.2.3. Te Linear Combination Fitting -- 3.5. Microfocused X-Ray Fluorescence Map Collection and Analysis -- 3.5.1. Experimental Conditions -- 3.5.2. Map Analysis -- 3.6. Electron Microprobe Analysis -- 3.6.1. Experimental Conditions -- Chapter 4. Results -- 4.1. Method Development and Verification -- 4.2. Elemental Analysis of Samples -- 4.3. Mass Balance -- 4.4. X-Ray Absorption Spectroscopy -- 4.4.1. Sulfur -- 4.4.2. Tellurium -- 4.5. Micro-focused X-Ray Maps -- 4.6. Electron Microprobe Analysis -- Chapter 5. Discussion -- 5.1. Mass Balance -- 5.2. Mine -- 5.3. Smelter -- 5.4. Refinery -- Chapter 6. Conclusions -- 6.1. Future Directions -- References

Coupled superconductors and beyond

This paper describes the events leading to the discovery of coupled superconductors, the author's move in the 1970s to a perspective where mind plays a role comparable to matter, and the remarkable hostility sometimes encountered by those who venture into unconventional areas.Comment: Invited paper for special issue of Low Temperature Physics/Fizika Nizkikh Temperatur devoted to "Quantum Coherent Effects in Superconductors and New Materials". 6pp. v5: open-access published versio

Don't forget the memory: Contribution of the T wave vector in localizing the site of origin of a monomorphic idiopathic ventricular tachycardia

SummaryWe report a case of cardiac memory following recurrent episodes of monomorphic idiopathic ventricular tachycardia and explain how it could be helpful in localizing the site of origin of the arrhythmia

Characterization of Respiratory and Cardiac Motion from Electro-Anatomical Mapping Data for Improved Fusion of MRI to Left Ventricular Electrograms

Accurate fusion of late gadolinium enhancement magnetic resonance imaging (MRI) and electro-anatomical voltage mapping (EAM) is required to evaluate the potential of MRI to identify the substrate of ventricular tachycardia. However, both datasets are not acquired at the same cardiac phase and EAM data is corrupted with respiratory motion limiting the accuracy of current rigid fusion techniques. Knowledge of cardiac and respiratory motion during EAM is thus required to enhance the fusion process. In this study, we propose a novel approach to characterize both cardiac and respiratory motion from EAM data using the temporal evolution of the 3D catheter location recorded from clinical EAM systems. Cardiac and respiratory motion components are extracted from the recorded catheter location using multi-band filters. Filters are calibrated for each EAM point using estimates of heart rate and respiratory rate. The method was first evaluated in numerical simulations using 3D models of cardiac and respiratory motions of the heart generated from real time MRI data acquired in 5 healthy subjects. An accuracy of 0.6–0.7 mm was found for both cardiac and respiratory motion estimates in numerical simulations. Cardiac and respiratory motions were then characterized in 27 patients who underwent LV mapping for treatment of ventricular tachycardia. Mean maximum amplitude of cardiac and respiratory motion was 10.2±2.7 mm (min = 5.5, max = 16.9) and 8.8±2.3 mm (min = 4.3, max = 14.8), respectively. 3D Cardiac and respiratory motions could be estimated from the recorded catheter location and the method does not rely on additional imaging modality such as X-ray fluoroscopy and can be used in conventional electrophysiology laboratory setting

The Predicted RNA-Binding Protein ETR-1/CELF1 Acts in Muscles To Regulate Neuroblast Migration in Caenorhabditis elegans

This work is licensed under a Creative Commons Attribution 4.0 International License.Neuroblast migration is a critical aspect of nervous system development (e.g., neural crest migration). In an unbiased forward genetic screen, we identified a novel player in neuroblast migration, the ETR-1/CELF1 RNA binding protein. CELF1 RNA binding proteins are involved in multiple aspects of RNA processing including alternative splicing, stability, and translation. We find that a specific mutation in alternatively-spliced exon 8 results in migration defects of the AQR and PQR neurons, and not the embryonic lethality and body wall muscle defects of complete knockdown of the locus. Surprisingly, ETR-1 was required in body wall muscle cells for AQR/PQR migration (i.e., it acts cell non-autonomously). Genetic interactions indicate that ETR-1 acts with Wnt signaling, either in the Wnt pathway or in a parallel pathway. Possibly, ETR-1 is involved in the production of a Wnt signal or a parallel signal by the body wall muscles that controls AQR and PQR neuronal migration. In humans, CELF1 is involved in a number of neuromuscular disorders. If the role of ETR-1/CELF1 is conserved, these disorders might also involve cell or neuronal migration. Finally, we describe a technique of amplicon sequencing to detect rare, cell-specific genome edits by CRISPR/Cas9 in vivo (CRISPR-seq) as an alternative to the T7E1 assay.NIH P40 OD010440National Institute of General Medical Sciences (P20GM103638)Madison and Lila Self Graduate Fellowship progra

Theranostic Imaging of the Kinases and Proteases that Modulate Cell Death and Survival

Several signaling cascades are involved in cell death, with a significant amount of crosstalk between them. Despite the complexity of these cascades several key pro-survival and pro-death players have been identified. These include PI3-kinase, AKT and caspase-3. Here we review the approaches used to date to perform molecular imaging of these important targets. We focus in particular on approaches that include the possibility of modulating the activity of these kinases and proteases in a theranostic approach

The Josephson effect throughout the BCS-BEC crossover

We study the stationary Josephson effect for neutral fermions across the BCS-BEC crossover, by solving numerically the Bogoliubov-de Gennes equations at zero temperature. The Josephson current is found to be considerably enhanced for all barriers at about unitarity. For vanishing barrier, the Josephson critical current approaches the Landau limiting value which, depending on the coupling, is determined by either pair-breaking or sound-mode excitations. In the coupling range from the BCS limit to unitarity, a procedure is proposed to extract the pairing gap from the Landau limiting current.Comment: 4 pages, 3 figures; improved version to appear in Phys. Rev. Let

Usefulness of electrophysiologic study to determine the clinical tolerance of arrhythmia recurrences during amiodarone therapy

The relation of clinical and electrophysiologic variables to outcome was evaluated in 121 patients treated with amiodarone for sustained ventricular tachyarrhythmias. Electrophysiologic study was performed in all patients a mean of 14 days after beginning amiodarone therapy. Forty-six patients who were given oral amiodarone therapy experienced arrhythmia recurrence. Multivariate analysis was performed using 16 clinical and electrophysiologic variables to determine which factors were associated with 1) arrhythmia recurrence and 2) a poorly tolerated arrhythmia recurrence (that is, cardiac arrest or sudden cardiac death) during oral amiodarone therapy. No variable predicted arrhythmia recurrence. Five variables correlated significantly with a poorly tolerated arrhythmia recurrence. Hemodynamic stability of the arrhythmia induced on electrophysiologic testing during amiodarone therapy had the best predictive value (p < 0.001). Younger age, lower ejection fraction, a poorly tolerated rhythm at clinical presentation and absence of left ventricular aneurysm were also associated with a poorly tolerated arrhythmia recurrence.Only 3 of 57 patients who had a well tolerated arrhythmia induced on electrophysiologic testing during amiodarone therapy had recurrence of a poorly tolerated arrhythmia versus 19 of 47 who had hemodynamically unstable arrhythmias induced during amiodarone therapy (p < 0.001). Thus, electrophysiologic testing during amiodarone therapy appears useful in identifying patients who are prone to have catastrophic arrhythmia recurrences and could allow for the institution of additional or alternative modes of therapy

Phase Modulated Thermal Conductance of Josephson Weak Links

We present a theory for quasiparticle heat transport through superconducting weak links. The thermal conductance depends on the phase difference ($\phi$) of the superconducting leads. Branch conversion processes, low-energy Andreev bound states near the contact and the suppression of the local density of states near the gap edge are related to phase-sensitive transport processes. Theoretical results for the influence of junction transparency, temperature and disorder, on the phase modulation of the conductance are reported. For high-transmission weak links, $D\to 1$, the formation of an Andreev bound state at $\epsilon_{\text{\tiny b}}=\Delta\cos(\phi/2)$ leads to suppression of the density of states for the continuum excitations that transport heat, and thus, to a reduction in the conductance for $\phi\simeq\pi$. For low-transmission ($D\ll 1$) barriers resonant scattering at energies $\epsilon\simeq(1+D/2)\Delta$ leads to an increase in the thermal conductance as $T$ drops below $T_c$ (for phase differences near $\phi=\pi$).Comment: 4 pages, 3 figures Expanded discussion of boundary conditions for Ricatti amplitude