Oil agglomeration of weakly hydrophobic coals and coal/pyrite mixtures

Abstract

Fine particle suspensions of various materials in water were agglomerated with heptane in a modified blender to determine the agglomeration characteristics of the solids. The materials included Upper Freeport coal, oxidized Upper Freeport coal, two batches of Illinois No. 6 coal, graphite, and iron pyrite. The response of these materials to oil agglomeration varied over a wide range and seemed to depend on their relative hydrophobicity. Treating the weakly hydrophobic materials with traces of sodium oleate greatly enhanced their response to oil agglomeration. The separation of mixtures of pyrite and various carbonaceous materials by selective agglomeration with heptane was also studied. While an excellent separation of graphite and pyrite was achieved, the separation of coal and pyrite proved elusive. surface areas, and adsorption isotherms for these samples were experimentally determined. The results (Table III) show that the measured contact angles in the large particle size fractions (-28 + 100 mesh and -28 mesh) are slightly smaller than those in the small particle size fractions (-100 mesh and -200 mesh). This may be attributed to the apparent differences in surface condition of the compressed coal pellet samples formed with large and small particle sizes. Hence the measured contact angle for the large particle size coal tends to underestimate the true contact angle. This phenomenon was also observed by Murata. 15 Considering the small differences in measured contact angles between these two size fractions of each group, it can be said that the particle size has only a minor effect on the contact angle. Disciplines Catalysis and ReactionAs expected, the surface area is smaller for the large size fraction than the small size fraction of coal samples. It is also found that coal with the smaller size fraction adsorbed more C0 2 on a unit weight basis. The increase in the external surface area for the finer coal particles is known to be the teason for the increased amount of C0 2 adsorption on a unit weight bases. However, when expressed on a unit surface area basis, the same amount of adsorption is observed. Similarly, the film pressure of each size fraction of these coal samples was compared, and little difference between the two size fractions was found for both of the tested groups. These results can be explained by the fact that when the coal particles are ground into smaller sizes, the increase in the total surface area is mostly due to the increase in the external surface area (assuming very few dead pores in the original coal particles), while the internal micropore surface area is the same for both the larger and smaller sizes of coal particles. ConclusivnsFrom the above discussion, it is clear that the LICADO process is a surface-property-driven process. The work performed so far indicates that the mechanism of the LICADO process is governed by the interactions among the interfacial, shear, and body forces present in the coal particle-liquid C0 2 -water system. The shear and body forces are ...

Sustained High Nutrient Supply As an Allelopathic Trigger between Periphytic Biofilm and Microcystis aeruginosa

“…All identified compounds of interest are hydrophobic. For example, the solubility of (9 Z )-octadec-9-enoic acid and (9 Z )-hexadec-9-enoic acid are both less than 10 μg L –1 (7.05 μg L –1 for (9Z)-octadec-9-enoic acid) . Furthermore, their densities are 0.89 g cm –3 and 0.85 g cm –3 , respectively and these “low density” compounds form micelles when mixed with water and can even form an “oil layer” which floats on the surface.…”

“…For example, the solubility of (9Z)-octadec-9-enoic acid and (9Z)hexadec-9-enoic acid are both less than 10 μg L −1 (7.05 μg L −1 for (9Z)-octadec-9-enoic acid). 38 Furthermore, their densities are 0.89 g cm −3 and 0.85 g cm −3 , respectively and these "low density" compounds form micelles when mixed with water 39 and can even form an "oil layer" which floats on the surface. Generally, M. aeruginosa inhabits the middle and upper layers of high nutrient medium (water) due to their heliotropic response.…”

Basic principles and mechanisms of selective oil agglomeration. Fossil energy interim report, October 1, 1983--September 30, 1992

“…For strongly hydrophobic materials, the maximum recovery approached 100% (refs. [5][6][7]26,27), and the principal effect of supplying excess oil was to increase the size of the agglomerates (refs. 6,7).…”

00/02252 Coal recovery from coal fines cleaning wastes by agglomeration with vegetable oils: effects of oil type and concentration

“…Oil agglomeration was found to be one of the most effective methods for cleaning coal at very fine particle size [9,10]. By contrast, vegetable oils were previously used in this laboratory as coal agglomerants with results comparable or even better [11] than those obtained employing light hydrocarbons, which were recognized to provide cleaner coal products [12][13][14][15]. However, the price of the hydrocarbons make their commercial use uncertain.…”