A mixer has a circular housing defining a mixing area for mixing and kneading of a gypsum slurry. A rotary disc is positioned in the housing and rotated in a predetermined rotational direction. A rotary driving shaft cointegrally connected with the rotary disc and a plurality of scrapers are positioned in the mixing area. A slurry discharge port is provided on an annular wall of the housing for feeding the gypsum slurry of the mixing area onto a sheet of paper for gypsum board liner. An opening of the slurry discharge port is divided into a plurality of narrow openings, so that fluid resistance on the gypsum slurry flowing out of the mixing area is increased. An annular basal part rotates integrally with the rotary disc and an inner end portion of the scraper is fixed to the annular basal part.

Apparatus and method in which a solid or liquid additive is dispensed within a mixing chamber for mixing with a fluid from the pressurized fluid flow line and is effective mixed in a vortex under vacuum while precluding contamination of the unused additive.

Apparatus and method in which a solid or liquid additive is dispensed within a mixing chamber for mixing with a fluid from the pressurized fluid flow line and is effective mixed in a vortex under vacuum while precluding contamination of the unused additive.

Apparatus and method in which a solid or liquid additive is dispensed within a mixing chamber for mixing with a fluid from the pressurized fluid flow line and is effective mixed in a vortex under vacuum while precluding contamination of the unused additive.

A continuous kneading device is provided with an upper trunk (1) to which a powder supply tube (3) through which quantified powder is supplied is connected and in which the powder is blended with a fluid, and a lower trunk (2) concentrically connected to the bottom of the upper trunk (1). The continuous kneading device continuously kneads the powder and the fluid by a first rotating kneading plate (10) built into the upper trunk (1) and a second rotating kneading plate (11) built into the lower trunk (2), wherein surfaces of the base metals of the first and second rotating kneading plates (10, 11) are covered with a coating material (50) for reducing friction when the powder and the fluid are kneaded together.

A mixing apparatus is provided that evenly mixes a powder raw material and a liquid raw material. The powder raw material is supplied to and spread out on a rotating disk to form a thin layer of dispersed particle swarms close to the periphery of the rotating disk. A rotary atomizer that synchronously rotates on the same axis is provided above the rotating disk. The liquid raw material is supplied to an inside surface of the rotary atomizer. Then, the liquid raw material is conducted to an atomizing head where the liquid raw material is atomized, and droplet swarms are horizontally radiated. The dispersed particle swarms and the droplet swarms are merged and condensed within a tapered wedge-shaped space, with the result that these swarms change into a fine and homogeneous mixture. The mixture is then radiated from the periphery.

A pretreatment mixing and stirring device includes a cylindrical housing having a top plate, a bottom plate arranged to oppose to the top plate, a side plate arranged between the top plate and the bottom plate, and a mixing and stirring region where a calcined gypsum and an additive are mixed and stirred in an interior surrounded by the top plate, the bottom plate, and the side plate, a disk-shaped rotating plate arranged inside the housing, a rotating drive shaft, penetrating the top or bottom plate, and coupled to the rotating plate, a calcined gypsum supply port, arranged in the top plate, and supplying the calcined gypsum to the mixing and stirring region, and an additive supply port, arranged in at least one of the top and side plates, and supplying the additive to the mixing and stirring region.