The Ribbon Blender MRBL houses two concentric helical ribbons on a common shaft running the length of a horizontal U-trough. The outer ribbon is wound in one helical direction; the inner ribbon is wound in the opposite direction. When the shaft rotates, the outer ribbon moves material inward from the ends toward the centre, while the inner ribbon simultaneously moves material outward from the centre toward the ends. This continuous counter-current flow pattern lifts and interpenetrates the two streams of material, producing uniform distribution throughout the batch.

The double-helical counter-current mechanism achieves uniform blending of free-flowing dry powders at relatively low RPM — typically 40–60 RPM — which minimises heat generation, particle attrition and the centrifugal segregation that occurs in blenders operating at higher shaft speeds. The MRBL is suited to free-flowing and mildly cohesive dry powders; for highly cohesive, sticky or semi-solid materials, the MPBL Paddle Blender is the appropriate selection.