An apparatus and a method for dispersing particulate materials prone to agglomeration, in a liquid. Particulate materials are exposed to a liquid and put into that liquid to form a suspension or a dispersion in a controlled method thereby minimizing agglomerates. The method uses mechanical/hydro mixing that prevents the physical deterioration of the particulate material and inhibits agglomeration of the particles. In many cases, these materials may be nanomaterials. Almost all particulate materials, can be handled in this manner. This method has been found to be especially useful for preparing solutions of exfoliated graphene and certain drugs.