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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 ...

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A polyanionic biopolymer known as alpha-ernulsan was found to flocculate fine particle suspensions of pyrite quite readily, but other materials including silica (quartz), kaolin, and a particular bituminous coal required activation in order to respond in large measure. Activation of these materials was achieved with small amounts of ferric iron which is known to hydrolyze to form ferric hydroxy complexes and conoidal particles of ferric hydroxide. When the positively charged hydrolyzed species of iron(III) were adsorbed by the negatively charged particles, the latter experienced a charge reversal which made them more receptive to adsorption of the polymeric anions. Larger amounts of ferric iron interfered with the flocculation of all the materials except pyrite, and the interference seemed due to the formation of ferric iron complexes with emulsan. Since high concentrations of ferric iron and low pH favored the flocculation of pyrite with emulsan but not the flocculation of the other materials, these conditions were applied to the selective flocculation of binary mixtures of pyrite and either silica, kaolin, or coal. Partial separation of the mixtures was achieved.