Batch Size Increase in Dry Blending and Mixing

Department of Chemical and Biochemical Engineering, Rutgers University, Piscataway, New Jersey, U.S.A. 

There are currently no mathematical techniques to predict blending behavior of granular components without prior experimental work. Therefore, blending studies start with a small scale, try-it-and-see approach. The first portion of this chapter is concerned with the following typical problem a 5-ft - capacity tumble blender filled to 50% of capacity and run at 15 rpm for 15 minutes produces the desired mixture homogeneity. What conditions 

Are variations to the blender geometry between scales acceptable  

Unfortimately, there is no generally accepted method for approaching this problem therefore, ad hoc approaches tend to be the rule rather than the exception. 

Further complicating the issue is that rotation rates for typical commercially available equipment are often fixed, obviating question (1) and suggesting that, imder such conditions, true dynamic or kinematic scale-up may not be possible. 

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Alexander AW, Muzzio FJ. 2006. Batch size increase in dry blending and mixing. In Levin M, editor. Pharmaceutical process scale-up. 2nd ed. New York Taylor Francis. 

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