This paper presents an improvement of the roll compaction process of dusty caustic magnesia carried out by using vinasses and molasses from the sugar beet industry as organic binders. The objective of this industrial study is to verify the possibility of increasing the particle size of the powdery raw material by granulation. It involved an instrumented pilot scale roller press (corrugated surface) to set the operating parameters and control the agglomeration process assessing the quality of the product established on a lot of final granules. As result, the effect of the addition of 5% (w/w) of binder by a spray nozzle atomizer on the caustic magnesia and the intensive mixing in a high shear mixer reduces notably the proportion of fines (by 30%) and increases significantly the rate of granules greater than 2 mm formed when the "moist powders" are compacted in the subsequent pressure agglomeration unit. This furtherance represents a process optimization strategy which increases the productivity and achieves a significant reduction in the quantum of failures. (C) 2012 Elsevier B.V. All rights reserved.