ABSTRACT
The addition of liquid binders to bulk solids has been employed to increase the cohesive properties of the bulk material. This technique is often used to decrease the dustiness of a bulk material, to enhance agglomeration processes, to increase green strength during tablet and mold production, and to prevent segregation tendencies [1]. For example, roofing tile production companies may occasionally add oil to the roofing granules to prevent segregation of fine and coarse granules as they are deposited on the asphalt shingle. Food industries, chemical producers,
and even wood manufactures add liquid binders to their briquetted or extruded products to produce a more robust particulate ensemble. Conversely, the presence of liquid in bulk powder materials can significantly increase the unconfined yield strength of the bulk and create significant arching and rathole tendencies in process equipment. These flow problems are responsible for many billions of dollars in lost revenue, additional operator involvement, and high maintenance cost to powder manufacturers. The mechanism behind increasing cohesiveness through the addition of liquid binders is not well understood but, in part, arises from the capillary forces between the individual particles. Understanding of these capillary forces will help prediction of the cohesive properties acting within a bulk material.
