Gelation of liquid bridges in spherical agglomeration

A method is introduced to increase agglomerate strength in an agitated system during spherical agglomeration. Spherical agglomeration is a process wherein the particles of dispersion are held together in aggregates by liquid bridges. The use of surfactants to improve wetting of the particulates by the bridging liquid often leads to lower interfacial tension, and liquid bridges too weak to withstand the levels of agitation required to bring the particles together. The approach suggested herein involves the addition of crosslinkable polymers to the agglomerating agent and effecting gelation as liquid bridge form. The added mechanical strength thus compensates for the reduction in agglomerate strength caused by the wetting agent. The approach is tested in a proof-of-principle practical application, viz., deinking of toner-printed paper. For the cases examined, the gelation of the liquid bridges significantly improves the agglomerate strength, as inferred from measurements of the agglomerate size distributions as functions of time for shear rates commonly encountered in a separation unit. Times required for gelation and for attainment of a steady-state aggregate size distribution are reasonable for this application.