1,867 research outputs found
Fluid dynamics based modelling of the Falcon concentrator for ultrafine particle beneficiation
No full textEnhanced gravity separators are widely used in minerals beneficiation, as their superior gravity field enables them to separate particles within narrow classes of density and size. This study aims to shed light on the Falcon concentrator’s ability to separate particles within size and density ranges lower than usual, say 5 to 60 μm and 1.2 to 3.0 s.g. respectively. As differential particle settling is expected to be the prevailing separation mechanism under such conditions, this study presents the workings of a predictive Falcon separation model that embeds phenomenological fluid and particle flow simulation inside the Falcon’s flowing film. Adding to the novelty of modelling the Falcon concentrator
using a fluid mechanics approach, one point of practical significance within this work is the derivation of the Falcon’s partition function from fluid flow simulation results
Beneficiation of concentrated ultrafine suspensions with a Falcon UF concentrator
No full textFalcon concentrators are enhanced gravity separators designed for concentrating fine particles. The Falcon UF model is unique in that it is dedicated to beneficiation of ultrafines, one key feature being that it does not make use of any fluidization water. We investigated the physics of particle transport inside Falcon concentrators, and concluded that separation efficiency is governed by differential settling velocity. We derived and published a predictive model of the partition function under dilute conditions. We intend to extend the initial model to concentrated ultrafine suspensions for application to industrial scenarios by adding hindered settling to account for solid concentration effects
Physical analysis and modeling of the Falcon concentrator for beneficiation of ultrafine particles
No full textA predictive model of the Falcon enhanced gravity separator has been derived from a physical analysis of its separation principle, and validated against experimental data. After summarizing the previous works that led to this model and the hypotheses on which they rely, the model is extended to cover a wide range of operating conditions and particle properties. The most significant development presented here is the extension of the analytical law to concentrated suspensions, which makes it applicable to actual plant operating conditions. Two examples of industrial use cases are described and studied by interrogation of the model: dredged sediment waste reduction and coal recovery from fine tailings. Comparisons with empirical studies available in the literature show a good agreement between model predictions and industrial data. The model is then used to identify separation efficiency limitations as well as possible solutions to overcome them. These two examples serve to show how this predictive model can be used to obtain valuable information to improve physical separation processes using a Falcon concentrator, or to evaluate Falcon separator’s abilities for new applications
Experimental validation of a fluid dynamics based model of the UF Falcon concentrator in the ultrafine range
No full textThe process of separating ultrafine particles, say below 80 μm, on the basis of density is a true technical challenge. Indeed, the separation process itself becomes very much size dependent with such fine particles, so that large enough density differentials are necessary for offsetting the strong particle size effect. Our study is concerned with understanding the limitations of the UF Falcon concentrator, an enhanced gravity separator specifically designed for treating slurries with ultrafines. To this end, based on a number of hypotheses, we have already derived and published a theoretical model of the UF Falcon concentrator for treating dilute suspensions. This paper presents the validation and calibration of this model, based on experimental measurements carried out under controlled conditions using a laboratory scale concentrator. By comparing measured and predicted separation results for particles with known size distribution and density, the work validates the key model hypotheses, thereby confirming our understanding of the physics of the separation process. Moreover, by changing operating conditions in a systematic manner, the work is able to calibrate the model so that it can be used to make quantitative prediction of the UF Falcons performance
M. Renna, S. Vaccari, Commento all’art. 40 c.p.a. (Contenuto del ricorso), in G. Falcon, B. Marchetti, F. Cortese (a cura di), Commentario breve al Codice del processo amministrativo, Padova, Cedam, 2021, p. 433 e ss
No full textCommento all'art. 40 c.p.a. (Contenuto del ricorso
Cap. III La vicenda storica del regionalismo - parr. 8 - 14
No full textIn questo contributo si è sottoposto ad analisi la recente vicenda storica del regionalismo italiano, dall'emersione del principio della leale collaborazione, fino ai più recenti svolgimenti. Si è dato conto in particolare delle due grandi riforme organiche che hanno inciso sul Titolo V della Parte II della Costituzione, analizzando soprattutto le relative linee di tendenza e di sviluppo. Si è dato conto del più recente tentativo di riformare la riforma e delle problematiche emerse soprattutto con riguardo ai tentativi di costituzionalizzare il principio di leale collaborazione
Vitellogenin and zona radiata proteins as biomarkers of endocrine disruption in peregrine falcon (Falco peregrinus)
No full textThe aim of this study was to test a specific method for the detection of Vitellogenin (Vtg) and Zona Radiata Proteins (Zrp) in plasma
from peregrine falcon (Falco peregrinus) as specific biomarkers for the evaluation of the effects of endocrine disruptors. The method was
assayed with different peregrine falcon individuals (including mature and immature birds of both sexes) from a Spanish population being
studied in terms of their contamination with organochlorine compounds with endocrine disrupting properties. This study shows that
mouse anti bird Vtg monoclonal antibody ND3C3 (Biosense) seems to be the most specific antibody in binding plasmatic lipoproteins
in peregrine falcon when compared to other anti Vtg antibodies. Rabbit anti salmon Zrp polyclonal antibodies O146 (Biosense) show
cross-reactivity with Zrp in the samples studied. These preliminary results confirm the applicability of both of these diagnostic tools
assayed (induction of Vtg and Zrp) in detecting exposure to Endocrine Disrupting Chemicals (EDCs) in this species. The increase of
Vtg and Zrp detected in male specimens suggest a potential hazard to EDCs in the peregrine falcon which represents a species still
affected by organochlorine compounds, and in particular those with estrogenic activity
Dynamic Modeling of Waste Incineration Systems - A Startup Procedure
No full textThe paper deals with the development of a dynamic model which allows to describe the behavior of a rotary kiln (primary combustion chamber with heterogeneous combustion) and the corresponding afterbumers system (secondary combustion chamber with homogeneous combustion). For sake of brevity, the analysis here reported will be limited to a startup procedure used, as specific application, to really check robustness and reliability of the model itself. Few comparisons with experimental data available from a commercial unit will be reported to complete the model validation
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