Strain Induced Percolation

Bridgwater, J.; Cook, H. H.; Drahun, J.A.

doi:10.1016/b978-0-08-028785-0.50015-0

Cited by 4 publications

(4 citation statements)

References 9 publications

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“…Like its non-centrifugal counterpart, the Reichert cone, the continuous Falcon can yield good recoveries, but at low upgrading ratios [15]. Upgrading stems from the different percolating velocity of particles through the bed, which is size, shape and density dependent [16]. Percolation is induced by the strain rate which develops as a result of the high rotation speed, both axially and radially.…”

Section: Basic Considerationsmentioning

confidence: 98%

A Study of the Falcon Concentrator

Laplante¹,

Buonvino²,

Veltmeyer³

et al. 1994

Canadian Metallurgical Quarterly

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A B6 Falcon Concentrator was tested on several systems: a synthetic magnetite-silica ore, a massive sulphide gold--eopper ore, a fine gold-pyrite-silica flotation tail, and a high-grade gold ore in a low sulphide gangue (cyclone overflow).The Falcon demonstrated its ability to achieve separation in all cases, but with varying degrees of success. For the magnetite-silica system, separation proceeded until the concentrate bed overloaded, at a mass of 300-400 g of magnetite. Recovery increased with decreasing particle size, down to 25-37 /lm, and in some cases even below 25 /lm. Bowl geometry (angle) and gangue size distribution were the most significant operating variables. Results with the massive sulphide ore were the poorest, with gold recoveries typically around 10-20% at very low upgrading ratios, 1:1-5:1. Gold recovery from the fine flotation tail ranged from 30 to 70% at upgrading ratios of 5-15. The high-grade gold cyclone overflow yielded a wide range of gold recoveries, with a very consistent relationship between recovery and mass processed. With a highgrade feed, a concentrate of 0.5% Au could be produced at a recovery of 50%.Resume-Un concentrateur Falcon, type B6, a ete utilise pour Ie traitement de plusieurs echantillons: un melange synthetique de magnetite-silice, un minerai or et cuivre de sulfures massifs, un rejet de flottation tres fin contenant de l'or, de la pyrite et de la silice, et un minerai d'or a haute teneur contenant peu de sulfures (sur-verse de cyclone).Le Falcon a pu enrichir les produits traites, avec plus ou moins de succes, selon Ie cas. Pour Ie melange magnetite-silice, la separation se poursuit tant que la bande de concentre n'est pas saturee, ce qui se produit lorsque de 300-400 g de magnetite ont ete recupere. La recuperation augmente a mesure que la taille des particules de magnetite diminue, jusqu'a 25-37 /lm, et meme dans certains cas, Ie -25 /lm. La geometrie du rotor et la granulometrie de la gangue sont les variables operatoires qui ont Ie plus d'effet sur la recuperation. C'est Ie minerai de sulfures massifs qui a donne les pires resultats, soit des recuperations en or de 10-20%

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Section: Basic Considerationsmentioning

confidence: 98%

A Study of the Falcon Concentrator

Laplante¹,

Buonvino²,

Veltmeyer³

et al. 1994

Canadian Metallurgical Quarterly

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“…Four areas of the bed were thus investigated. This work is described in detail elsewhere (Cook and Bridgwater, 1982;Bridgwater et al, 1983), but the key points will be reviewed here. The findings from these studies will be assessed in relation to the findings here and those of others.…”

Section: The Canadian Journal Of Chemical Engineering Volume 63 Aprmentioning

confidence: 99%

Particle residence times in the continuous spouting of mixtures

Cook

Bridgwater

1985

Can J Chem Eng

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A magnetic labelling technique has been used to examine particle residence time distributions in a continuous spouted bed. For a single particle species, the nearly perfect mixing observed found by others is confirmed. For a binary particle system, perfect mixing of each component is found, but the mean residence times are not equal. The ratio of mean residence times is found to be dependent on the fountain height and bed depth; the influence of some of the underlying physical mechanisms in the fountain, free surface and outlet regions can be seen.

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“…Two different processes govern the infiltration of sand for a gravel matrix, namely static sorting and kinetic sieving. Static sorting of sand into an immobile gravel framework as “spontaneous percolation” (Bacchi et al., 2014; Bridgwater et al., 1969; Kleinhans and Van Rijn, 2002) has received extensive attention, due to its ecological significance primarily related to the implications in terms of reproduction of salmonids (Richards & Bacon, 1994; Sklar et al., 2009). The process was studied in laboratory experiments (Beschta & Jackson, 1979; Carling, 1984; Diplas & Parker, 1992; Wooster et al., 2008), in the field (Carling & McCahon, 1987; Frostick et al., 1984; Lisle, 1989), and simulated in numerical models (Chassagne et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Hydrograph Shape Impact on Sand Infiltration and Sediment Transport Dynamics in Gravel‐Bed Rivers

Ravazzolo

Mao

Friedrich

2022

Water Resources Research

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A wide range of sediment grain sizes (from fine sand to pebbles) can be found in gravel-bed rivers. In fully alluvial systems, most of the size fractions (often differentiated into fine and coarse grains) can be actively transported during flood events. Sediment can be transported as bedload, suspended load, or can migrate inside the bed layer. For coarse grain sizes, the predominant transport process is bedload, whereas the influence of suspended load is negligible. In addition to bedload, fine grains can also be transported within the water column, by being kept in suspension by turbulence generated near the channel bed. The resultant turbulent flow must be equal or exceed the particle fall velocity to sustain suspended sediment load. Mobility and composition of the bed (e.g., grain size distribution, porosity) can change drastically during a flood event. In this gravel-bed study, we consider sand being transported as bedload only. Coarse grains can create interstitial spaces (pore space), that finer grains can occupy. The porosity of a channel bed will thus depend on the size and the heterogeneity of a sediment mixture (Standish & Borger, 1979). Two different processes govern the infiltration of sand for a gravel matrix, namely static sorting and kinetic sieving. Static sorting of sand into an immobile gravel framework Abstract Sand (i.e., < 2 mm) infiltration into a gravel bed is recognized to affect sediment dynamics of coarser fractions (i.e., entrainment and transport rate), near-bed velocities, bed morphology, and to pose significant engineering and ecological issues. Local hydraulics, sediment dynamics, and sand infiltration into the gravel matrix are related and mutually affect each other in gravel-bed rivers. However, relatively little research has been done to explore sediment dynamics and sand infiltration in a mobile gravel-bed under unsteady flow conditions. In the present study, we experimentally simulated three hydrographs of different durations of rising and falling limbs, and monitored sand infiltration over beds with a coarse and a fine grain size distribution. Results confirmed that the addition of sand enhances sediment dynamics. Moreover, the shape of the rising limb of the hydrograph was responsible for altering identified sand infiltration processes and bedload rate. Short time-to-peak floods (i.e., short time from the start to the peak of the hydrograph) experienced higher sediment transport rates during the falling limb than the rising limb of the hydrograph, favoring sand infiltration. In contrast, long time-to-peak floods (i.e., long time from the start to the peak of the hydrograph) experienced higher sediment transport rates during the rising limb than the falling limb of the hydrograph, resulting in reduced sand infiltration.Plain Language Summary Understanding how sediment is transported during floods is important, as their movement affects channel morphology and river ecology. Fine sediment can infiltrate gravel bed-rivers, a process that depends on the local hydraulics, the size...

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Strain Induced Percolation

Cited by 4 publications

References 9 publications

A Study of the Falcon Concentrator

A Study of the Falcon Concentrator

Particle residence times in the continuous spouting of mixtures

Hydrograph Shape Impact on Sand Infiltration and Sediment Transport Dynamics in Gravel‐Bed Rivers

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