Side entry fluid mixing

A mixing system for circulating and suspending particles in a suspension having at least two phases in a tank having a bottom and a side wall about a center and having first and second interior regions which face each other, which system comprises a cluster comprising a plurality of mixers entering said tank through said side wall in said second region and disposed along said side wall in side-by-side relationship in a zone which subtends a sector of about 100.degree. between radial lines to the center and are symmetrically disposed about a radial line to the center, a first and second of said plurality of mixers being disposed at opposite ends of said cluster and being separated by more than 60.degree. defined between radial lines from said center to said side wall and said second region, said mixers having axial flow impellers and shafts which drive said suspension from said second to said first region, thereby establishing in the tank a circulating flow along the bottom, upwardly along the said wall and said first region and downwardly along said side wall in said second region, and said mixers being in spatial and orientational relationships such that the axes of said impellers do not intersect within the tank and said flow from each of said mixers is in substantially non-interfering relationship along the bottom of said tank between said first and second regions.