Heap Leaching: Modelling and Forecasting Using CFD Technology

Heap leach operations typically employ some form of modelling and forecasting tools to predict cash flow margins and project viability. However, these vary from simple spreadsheets to phenomenological models, with more complex models not commonly employed as they require the greatest amount of time and effort. Yet, accurate production modelling and forecasting are essential for managing production and potentially critical for successful operation of a complex heap, time and effort spent in setting up modelling tools initially may increase profitability in the long term. A brief overview of various modelling approaches is presented, but this paper focuses on the capabilities of a computational fluid dynamics (CFD) model. Advances in computational capability allow for complex CFD models, coupled with leach kinetic models, to be applied to complex ore bodies. In this paper a comprehensive hydrodynamic CFD model is described and applied to chalcopyrite dissolution under heap operating conditions. The model is parameterized against experimental data and validated against a range of experimental leach tests under different thermal conditions. A three-dimensional ‘virtual’ heap, under fluctuating meteorological conditions, is simulated. Continuous and intermittent irrigation is investigated, showing copper recovery per unit volume of applied leach solution to be slightly increased for pulse irrigation

Terminal 77

Located south of Dallas, Texas, on Highway 77, a 550,000 sf site was transformed into a fueling station for Semi-trailer trucks. Creating a set of parameters, such as vehicular type, turn radius, and maximum vehicle dimensions, a systematic approach was organized in which to cultivate an architecture. The fueling station was reduced to three components: an area to fuel, an area to park, and an area leading to amenities. Researching the audience that would occupy the architecture, it was found that a further separation between the public and the truck drivers would be necessary. The solution was to make a fueling station that harbors a triple story configuration: the Trucker’s Haven, the People’s Haven and the Meditation Haven. This allowed the much disrespected truck driver a private plane on which they could affect an honorable existence. If need be, truckers could leave this haven, emerging on the upper most level, signaling a poetical release and meditative transformation. Reflecting on the fast pace nature of contemporary mass-transportation of goods and products, the meditation chamber was inserted into the canopy of the uppermost structure, violating a space that would otherwise be purely mechanical, in order to slow down the pace of daily rituals and allow a sense of exploration and removal from a culture of constant movement

Orbital Debris Observations with WFCAM

The United Kingdom Infrared Telescope has been operating for 35 years on the summit of Mauna Kea as a premier Infrared astronomical facility. In its 35th year the telescope has been turned over to a new operating group consisting of University of Arizona, University of Hawaii and the LM Advanced Technology Center. UKIRT will continue its astronomical mission with a portion of observing time dedicated to orbital debris and Near Earth Object detection and characterization. During the past 10 years the UKIRT Wide Field CAMera (WFCAM) has been performing large area astronomical surveys in the J, H and K bands. The data for these surveys have been reduced by the Cambridge Astronomical Survey Unit in Cambridge, England and archived by the Wide Field Astronomy Unit in Edinburgh, Scotland. During January and February of 2014 the Wide Field CAMera (WFCAM) was used to scan through the geostationary satellite belt detecting operational satellites as well as nearby debris. Accurate photometric and astrometric parameters have been developed by CASU for each of the detections and all data has been archived by WFAU

Clinical and cost effectiveness of a system for turning and positioning intensive care unit patients, when compared to usual care turning and positioning devices, for the prevention of hospital-acquired pressure injuries

Pressure injuries affect 13.1% to 45.5% of patients in the intensive care unit and lead to pain and discomfort for patients, burden on healthcare providers, and unnecessary cost to the health system. Turning and positioning systems offer improvements on usual care devices, however the evidence of the effectiveness of such systems is still emerging. We conducted an investigator initiated, prospective, single centre, two group, non-blinded, randomised controlled trial to determine the effectiveness of a system for turning and positioning intensive care unit patients, when compared to usual care turning and positioning devices, for preventing PIs. The trial was prematurely discontinued after enrolment of 78 participants due to COVID-19 pandemic related challenges and lower than expected enrolment rate. The study groups were comparable on baseline characteristics and adherence to the interventions was high. Four participants developed a PI (in the sacral, ischial tuberosity or buttock region), n = 2 each in the intervention and control group. Each participant developed one PI. As the trial is underpowered, these findings do not provide an indication of the clinical effectiveness of the interventions. There was no participant drop-out or withdrawal and there were no adverse events, device deficiencies, or adverse device effects identified or reported. The results of our study (in particular those pertaining to enrolment, intervention adherence and safety) provide considerations for future trials that seek to investigate how to prevent PIs among ICU patients.info:eu-repo/semantics/publishedVersio

Navigating the Contested Terrain of Teacher Education Policy and Practice: Authors Respond to SCALE

Stanford Center for Assessment, Learning, and Equity (SCALE) provided a commentary on the manuscripts in the first part of this special issue, which highlighted the benefits of edTPA and the necessity for such assessment programs to improve teacher education and strengthen teaching practices. In turn, the authors responded to the SCALE commentary. The authors’ responses raise concerns about equity, fairness, and unintended consequences of teacher performance assessments. These responses highlight the need for continued dialogue on ways to improve teacher education and strengthen the teaching profession

Kinesin heads fused to hinge-free myosin tails drive efficient motility

AbstractThe rat kinesin motor domain was fused at residues 433, 411, 376 or 367, respectively, to the C-terminal 1185, 1187, 1197 or 1185 residues of the brush border myosin tail. In motility assays, K433myt and K411myt, which preserve the head-proximal kinesin hinge, and K367myt, which deletes it, drove rapid microtubule sliding (∼0.6 μms−1) that was optimal when the head-pairs were spaced apart by adding 1:1 headless myosin tails. K376myt, which partially deletes the head-proximal hinge, showed poor motility in sliding assays but wild type processivity, velocity and stall force in single molecule optical trapping. Accordingly, the head-proximal kinesin hinge is functionally dispensable