Agglomeration by immiscible liquid wetting

Fine particles in liquid suspension can readily be formed into large dense agglomerates of considerable integrity by the addition of suitable amounts of 

A simple example of immiscible liquid wetting is the addition of oil to a fine coal suspension to agglomerate and remove the carbon constituents while the inorganic impurities (ash constituents) remain in suspension and are rejected. A number of such coal cleaning processes, such as the Trent Process [3], the Convertol Process [4] and the Spherical Agglomeration Process [5], have been developed and used in this century. As discussed below, developments of the latter process have shown that many other applications are possible for immiscible liquid wetting. 

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Examples of surface conditioning and selective agglomeration by immiscible liquid wetting [6]. 

Spherical agglomeration, see Agglomeration by immiscible liquid wetting Spouted bed granulation... 

The general relationships described above are not specific to a certain system. However, given the need for optimal separation of valuable particles from the associated gangue, the colloid and surface chemistries that are involved may be quite complex. As in the flotation process, selective agglomeration by immiscible liquids depends strongly on the relative wettability of surfaces, and the same fundamentals of surface chemistry apply to the conditioning of particles to yield the required affinity for the wetting liquid. 

Emulsion flotation is analogous to carrier flotation. Here, small-sized particles become attached to the surfaces of oil droplets (the carrier droplets). The carrier droplets attach to the air bubbles and the combined aggregates of small desired particles, carrier droplets, and air bubbles float to form the froth. An example is the emulsion flotation of submicrometre-sized diamond particles with isooctane. Emulsion flotation has also been applied to the flotation of minerals that are not readily wetted by water, such as graphite, sulfur, molybdenite, and coal [623]. Some oils used in emulsion flotation include mixed cresols (cresylic acid), pine oil, aliphatic alcohols, kerosene, fuel oil, and gas oil [623], A related use of a second, immiscible liquid to aid in particle separation is in agglomeration flocculation (see Section 5.6.4). 

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