Surface characteristics of coal-oil agglomerates in the floc regime

Darcovich, K.; Capes, C.E.; Talbot, F. D. F.

doi:10.1021/ef00013a011

Cited by 19 publications

(7 citation statements)

References 1 publication

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“…At dosages below 10 -20 wt% the structural integrity of the agglomerates is low and as such they become difficult to recover using a screen or other gravity separation technique. However, many authors have noted that for fine coal agglomeration to be a commercial success, the level, and thus cost, of the oil must be significantly reduced (Darcovich et al, 1988;Mehrotra et al, 1983;Shrauti and Arnold, 1994). Therefore, a new binder was investigated in this work in an attempt to reduce the amount of oil required and develop an economically viable agglomeration process.…”

Section: Introductionmentioning

confidence: 99%

Selective agglomeration of fine coal using a water-in-oil emulsion

Netten

Moreno-Atanasio

Galvin

2016

Chemical Engineering Research and Design

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Fine coal may be separated from an aqueous suspension of coal and mineral particles through the application of a pure oil. The pure oil preferentially wets and agglomerates only the coal, forming a high quality, granular product. However, the use of the pure oil also comes at a relatively high cost and this cost prohibits commercial implementation of this process. In this work a new, economic binder, was introduced. This binder consisted of a high internal phase water-in-oil emulsion which was 95 vol% water and 5 vol% organic. This type of binder was selected as it possessed the hydrophobic surface functionality of oil while the space filling functionality of the binder was primarily satisfied by the dispersed water droplets within the emulsion. The application of this emulsion in the agglomeration process led to a 10-fold reduction in the organic liquid dosage required to achieve agglomeration as compared a pure oil binder. It was also observed that the agglomeration time required when using the emulsion binder was one order of magnitude less than required when using a pure oil binder. This variation was considered to result from the five orders of magnitude difference in the viscosity of the two binders.

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Section: Introductionmentioning

confidence: 99%

Selective agglomeration of fine coal using a water-in-oil emulsion

Netten

Moreno-Atanasio

Galvin

2016

Chemical Engineering Research and Design

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“…Tampy et al modified the Washburn technique by developing an analytical method to determine the surface energy changes associated with wetting based on the fundamental equations of fluid transport through a packed powder bed of solids. Darcovich et al . used the adhesion technique to study the surfaceproperties of oil agglomerates made from high-purity coal, using hexadecane as the bridging liquid.…”

Section: Introductionmentioning

confidence: 99%

“…Tampy et al 9 modified the Washburn technique by developing an analytical method to determine the surface energy changes associated with wetting based on the fundamental equations of fluid transport through a packed powder bed of solids. Darcovich et al 10 properties of oil agglomerates made from high-purity coal, using hexadecane as the bridging liquid. Fuerstenau et al 11 and Marmur et al 12 developed a film flotation technique to obtain the distribution of the critical wetting surface energy and the fractions of hydrophobicity for the fine particle populations from film flotation responses.…”

Section: Introductionmentioning

confidence: 99%

Surface Energy and Induction Time of Fine Coals Treated with Various Levels of Dispersed Collector and Their Correlation to Flotation Responses

Peng

1996

Energy Fuels

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Separation of fine coal in froth flotation relies upon the wettability difference between the coal-rich and mineral-rich particles in the aqueous solution. Two methods were used to measure the wettability of six ranks of coal as well as coal samples treated with various levels of dispersed collector in aqueous solution. Wettability was determined by measuring the distribution of critical wetting surface tension, i.e., surface energy, using the film flotation technique and by measuring the induction time, i.e., bubble−particle attachment time, of the material. The wetting of coal particles is strongly dependent upon the coalification processes and can be affected by ash content. For anthracite coal with a high ash content, very high surface energy and intermediate induction time were measured, but intermediate floatability with a very good ash rejection was obtained. Sub-bituminous coal with low mineral inclusion was found to have a relatively low surface energy, and thus a high floatability, but very poor selectivity was observed, which was reflected in lengthened induction time. When dynamics of flotation behaviors are involved, flotation results can be better interpreted by induction time. For dispersed collector-treated coal samples, an increase in collector dispersion (i.e., a decrease in kerosene droplet size), by direct liquid collector mechanical agitation, ultrasonic energy emulsification, or atomization, caused decreases in surface energy and induction time and closely matched the increase of flotation recovery and selectivity. With similar particle density, mineral liberation conditions, and particle size, the induction time was found to be closely related to the mean critical surface tension for untreated coal samples and for HV-bituminous coal samples treated by various levels of dispersed collector.

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“…The feed factor, f F in equation 6 was found to be 1.85 for average feed-particle diameters <30 mm, and 2.17 for diameters >30 mm. Equation 6 predicts the binding liquid content for wet agglomeration with an accuracy of only $30%, since liquid bonding is a function of the particle size and distribution, particle morphology and the interfacial properties of the system (56). Typical values of moisture content required for balling a variety of materials are listed in Table 2.…”

Section: Agglomeration By Tumbling and Other Agitation Methodsmentioning

confidence: 99%

Particle Size Enlargement

Darcovich

2008

Kirk-Othmer Encyclopedia of Chemical Technology

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Size enlargement concerns those processes that bring together fine powder particles into larger masses to improve the properties of the powders. Many diverse industries benefit from size enlargement processes. Examples discussed herein include fertilizer granulation, iron ore pelletization, tablet feeds for pharmaceuticals, instant food products, and the processing of mineral and chemical products. This article primarily considers those processes in which the creation of coarse granular material from fines is the objective. The characteristics of individual agglomerates are important only in their effect on the properties of the bulk granular product. Following an initial discussion of particle‐bonding mechanisms and the theory and measurement of agglomerate strength, size enlargement processes and equipment, including principal design parameters, are described. These processes are considered on the basis of the principal mechanism used to bring the particles together into agglomerates. The categories used are agglomeration by tumbling and other agitation methods, pressure compaction and extrusion methods, heat reaction, fusion, and drying methods, and agglomeration from liquid suspensions by competitive wetting.

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Surface characteristics of coal-oil agglomerates in the floc regime

Cited by 19 publications

References 1 publication

Selective agglomeration of fine coal using a water-in-oil emulsion

Selective agglomeration of fine coal using a water-in-oil emulsion

Surface Energy and Induction Time of Fine Coals Treated with Various Levels of Dispersed Collector and Their Correlation to Flotation Responses

Particle Size Enlargement

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