SPOUTED BED ELECTROWINNING OF ZINC .2. INVESTIGATIONS OF THE DYNAMICSOF PARTICLES IN LARGE THIN SPOUTED BEDS

The behavior of particles in thin spouted beds, mostly equipped with d raft tubes, has been investigated. Three apparatuses have been used: a laboratory-scale cylindrical bed, a 2-m-tall ''flat'' (rectangular cr oss section) bed and a 2-m-wide flat bed, the last equipped with multi ple draft tubes. Most of the results were obtained on the tall bed. Mi nimum spouting flow rate, pressure distribution, particle velocities, and solid circulation rates were determined as a function of bed geome try (including draft tube dimensions and position). Observations were made of the direction of liquid flow in the bed outside the draft tube and of the occurrence of zones in the bed where the particles appeare d stationary. The wide bed was used to determine that there is a maxim um separation between draft tubes beyond which particles cannot be kep t in motion across the whole width of the bed.