Processing Magazine

Fluidized Bed Mixer

June 26, 2012

The new Fluidized Bed Mixer model MF-5-SS from Munson Machinery, gently mixes low- to medium-density bulk materials, including liquid additions, in 10 seconds to two minutes, with 30 seconds typical. Unlike ribbon, paddle and plow blenders with a single shaft turning agitator blades slowly within a U-shaped trough, this specialized machine has two counter-rotating shafts turning paddle agitators rapidly within two, parallel U-shaped troughs. Flat, angular paddles with overlapping paths sweep material from the troughs toward the center and upward, causing it to become airborne in a "fluidized zone" above the longitudinal centerline of the mixing chamber, where discreet particles of batch ingredients readily intersperse, regardless of disparities in particle size, shape or bulk density. High- or low-viscosity liquids sprayed into the fluidized zone disperse readily throughout the batch, allowing liquids to be added in relatively high ratios while maintaining free-flowing characteristics of the batch. The mixing action is said to minimize shear, which together with short mixing times, reduces product degradation. According to the company, the mixer discharges rapidly through full-length, drop-bottom gates, and evacuates a greater percentage of material than conventional agitated machines, reducing the need to manually remove, and waste, residual material between product changeovers.