Particle suspension in (air-agitated) Pachuca tanks

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Process metallurgy and materials processing science, 1998-04, Vol.29 (2), p.339-349
• Main Authors: ROY, G. G, SHEKHAR, R, MEHROTRA, S. P
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Hydrometallurgy; Metals. Metallurgy; Production of metals; Production of non ferrous metals. Process materials
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-998-0111-1

Particle suspension is an important parameter in the design of an energy-efficient Pachuca tank. Unfortunately, very little attention has been forcused on the suspension behavior of air-agitated Pachucas. In the present investigation, therefore, extensive experiments have been carried out in three laboratory-scale Pachuca tanks to examine the effect of design and operating parameters, and scale-up, on particle suspension. A mathematical model that combines the Bernoulli's equation and the theory of transport of particles in the horizontal flow of a liquid has been developed to predict the critical gas velocity for particle suspension in Pachuca tanks. Some important results, crucial to the design and scale-up of Pachuca tanks, have emerged. Full-center-column (FCC) Pachuca tanks with a draft tube-to-tank diameter ratio (D sub d /D sub t ) on the order of 0.1 are found to be energetically more efficient in suspending particles than free-air-lift (FAL) and stub-column (SC) Pachuca tanks. It is also observed that taller tanks require lower air flow rates for particle suspension than shallower tanks. Finally, it is explained why industrial Pachuca tanks operate at lower air velocities than laboratory-scale tanks.