The mixing time and power consumption of a helical double-ribbon impeller during blending of normal corn starch and icing sugar were studied. The approach took into account representative physical, flow and frictional properties of individual components and a 50:50 (w:w) blend, operating conditions and impeller characteristic dimensions. Physical tests showed the powders to be cohesive, hyperfine/superfine, with fair to good flow properties and different internal friction coefficient. Operating conditions played an important role in mixing time. Power consumption data were correlated with relevant powder physical properties; bulk density (rho(b)) and friction coefficient (mu(i)), system dimensions; impeller volume (V-1) and length (L-1), and operating conditions; load ratio (f) and impeller speed (N), by the relationship P = 0.21[(rho(b)mu(i))(V1L1)(fN)g]. A dimensionless correlation between the power number (N-p = P/rho(bDoN5)-N-3) and the effective cohesion number (N-Ce = [rho(bDoN2)-N-4/F-C][K-p(f)/f]) was obtained for the impeller; N-p decreased with increasing N-Ce. (C) 2014 Elsevier Ltd. All rights reserved.