Abstract: Problems occur in a bead mill due to wear on a sealing member of a sealing device disposed on a contact portion between a rotating portion and slurry, and due to the adhesion of deposits on the sealing device. A bead mill device that stirs a mixture of slurry and beads in a vertical cylindrical container includes a slurry storage vessel disposed above the cylindrical container, and a slurry flow passage through which the slurry flows from the slurry storage vessel into the cylindrical container. A component that causes the slurry in the slurry flow passage to flow downward is disposed on a rotary shaft. Further, a component for suppressing the flow of the slurry is disposed in the slurry storage vessel. This structure obviates the need to dispose a mechanical sealing device on the rotary shaft.

Abstract: Provided is an organic nanoparticle production method comprising a step in which a mixture of beads having an average particle size at least 0.15 mm and no more than a value (mm) calculated by the formula 1.07?0.11×[outer peripheral speed of the stirring rotor (m/sec)] and a slurry containing organic particles is stirred by a stirring rotor rotating at an outer peripheral speed of 7 m/sec or less in a vessel of a wet bead mill.

Abstract: A method for the production of the present disclosure comprises: a) a step of agitating a mixture containing a material to be ground, beads and a dispersion medium in a bead mill; and b) a step of adjusting the pH of the mixture. This method reduces a contamination caused by grinding process using a bead mill.