Estimation of the distribution of surface sites and contact angles on coal particles from film flotation data

Fuerstenau, D.W.; Diao, J.; Hanson, James S.

doi:10.1021/ef00019a007

Cited by 45 publications

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“…The Cassie equation has been used in several sessile drop studies to explain and predict the contact angle of a heterogeneous surface, such as coal (Ding, 2009;Drelich et al, 1996;Fuerstenau et al, 1990;Gosiewska et al, 2002;He and Laskowski, 1992;Keller, 1987;Rosenbaum and Fuerstenau, 1984). Studies have demonstrated that lithotypes have unique wetting surfaces, with inertinite rich coal creating a mean contact angle of 70°, in vitrinite rich the angle is 80º (Ofori et al, 2010) and liptinite rich the angle is 110° (Keller, 1987).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…As previously stated, some researchers have attempted to account for contact angles based on the differences between coal maceral contents and rank using the Cassie equation, as well as through carbon content and degree of surface oxidation expressed in the Keller equation (Ding, 2009;Drelich et al, 1996;Fuerstenau et al, 1990;Gosiewska et al, 2002;He and Laskowski, 1992;Keller, 1987;Rosenbaum and Fuerstenau, 1984). Noting the high level of heterogeneity in coal, and the need to clearly quantify the surface composition of the material we take a simpler approach in which there are four principle constituents that determine the wetting angle: bright coal (mildly hydrophobic); dull coal (mildly hydrophilic); void space (completely non-wetting); mineral matter (highly wetting).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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The effect of rank, lithotype and roughness on contact angle measurements in coal cleats

Mahoney

Rufford

Johnson

et al. 2017

International Journal of Coal Geology

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Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Accepted Manuscriptmentioning

confidence: 99%

The effect of rank, lithotype and roughness on contact angle measurements in coal cleats

Mahoney

Rufford

Johnson

et al. 2017

International Journal of Coal Geology

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“…In the approach developed here, it is necessary to know the value of c for the individual particles 20) . Since any point along a film flotation plot (a plot of the fraction of particles floating versus the liquid surface tension) represents conditions for zero contact angle at a specific surface tension, the distribution of wetting surface tensions obtained from film flotation results is the starting experimental information needed to evaluate contact angles.…”

Section: Film Flotationmentioning

confidence: 99%

Characterization of the Wetting and Dewetting Behavior of Powders

Chander

Hogg

Fuerstenau³

2007

KONA

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“…The Cassie Equation (Cassie, 1948;Cassie and Baxter, 1944) where θ1 and θ2 are the contact angles for different materials, and x1 and x2 are the fraction of surface each material covers and θc is the overall wetting angle. The Cassie equation has been used in several Sessile drop studies to explain and predict the contact angle of a heterogeneous surface, such as coal (Ding, 2009;Drelich et al, 1996;Fuerstenau et al, 1990;Gosiewska et al, 2002b;He and Laskowski, 1992;Keller, 1987;Rosenbaum and Fuerstenau, 1984 …”

Section: Techniques To Measure and Assess Wettabilitymentioning

confidence: 99%

“…As previously stated, some researchers have attempted to account for contact angles based on the differences between coal maceral contents and rank using the Cassie equation, as well as through carbon content and degree of surface oxidation expressed in the Keller equation (Ding, 2009;Drelich et al, 1996;Fuerstenau et al, 1990;Gosiewska et al, 2002b;He and Laskowski, 1992;Keller, 1987;Rosenbaum and Fuerstenau, 1984). Noting the high level of heterogeneity in coal, and the need to clearly quantify the surface composition of the material we take a simpler approach in which there are four principle constituents that determine the wetting angle: bright coal (mildly hydrophobic); dull coal (mildly hydrophilic); void space (completely non-wetting); mineral matter (highly wetting).…”

Section: Contact Angle Measurementsmentioning

confidence: 99%

The Effect of Water Occlusion on Gas Production in Coal

Mahoney¹

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Relative permeability is of fundamental importance to understand and model the flow of hydrocarbons and water in porous rocks including coal, and thus relative permeability is critical in prediction of commercial gas and water production rates from coal seam gas (CSG) reservoirs.Despite relative permeability being a primary parameter for determining reservoir performance, the fundamental physics of how or where water may occlude or block cleats in a coal seam, and thereby interfere with gas production rates, is not fully understood. This project aims to improve the understanding of water occlusion in CSG reservoirs through fluid experiments with model coal cleats and to evaluate the potential impact of water occlusion of reservoir performance.The aim of this thesis is to develop a new experimental methodology that can be used identify the main control factors that affect wettability in coal. There are two key objectives to satisfy the thesis aim 1) develop methods to make artificial channels in coal and 2) create a world first microfluidic device that assess micro scale flow through coal cleats, known as the cleat flow cell (CFC). The initial features to be evaluated will include: lithotype, surface roughness, surface composition, specifically chemical functional groups and pressure. oxygen plasma with a photolithography process to make the desired pattern on coal surface, UV Laser ablation, mechanical machining, a mechanical scratch technique, and a chemical etching technique that used potassium permanganate (KMnO4). Characteristics of the artificial channels were assessed using a surface step profiler, scanning electron microscopy, micro-Raman spectroscopy and light microscopy. A sixth methodology to create an artificial channel using pressed coal powder was also used as a means of evaluating the influence of the surface chemistry on the wetting behaviour, without the interference of surface topography.In Chapter Five, I report the effect of rank and lithotype on the wettability of coal in microfluidic experiments in two types of artificial microchannels; (1) reactive ion etched (RIE) channels and (2) die-cast channels prepared by pressing powdered lithotype concentrates. Contact angles and entry pressures of air and water in the artificial cleats were measured in imbibition experiments performed iii with a CFC. The relative contact angles measured in CFC imbibition experiments were in the range 110 -140° in the RIE channels and 85°-115° in the pressed discs, which are larger contact angles than measured on the flat bulk surfaces of these samples by the conventional sessile drop technique (58°-85°). The CFC observations show that the surface roughness of coal in inertinite-rich dull bands effects contact angle and the entry pressure of the air-water interface differently to the vitrinite-rich bright bands, with both lithotypes presenting unique wetting states. Drainage experiments revealed a thin residual water film on the inertinite cleat wall, not observed on the smoother vitrinite channel. were hydr...

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Estimation of the distribution of surface sites and contact angles on coal particles from film flotation data

Cited by 45 publications

References 0 publications

The effect of rank, lithotype and roughness on contact angle measurements in coal cleats

The effect of rank, lithotype and roughness on contact angle measurements in coal cleats

Characterization of the Wetting and Dewetting Behavior of Powders

The Effect of Water Occlusion on Gas Production in Coal

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