Abstract: The apparatus includes a two-stage mixer formed within a single housing and including a first high shear mixer and a second low shear mixer. Plaster slurry is formed in the first mixer. A partition is laid on a first fixing sheet, a portion laid on a second fixing sheet, and the remainder discharged to the second mixer. In the second mixer, foam is added and the formed slurry is laid on the unformed slurry on the first fixing sheet. The unformed slurry in the second fixing sheet is brought to the formed slurry to join the product.

Abstract: The apparatus includes a two-stage mixer formed within a single housing and including a first high shear mixer and a second low shear mixer. Plaster slurry is formed in the first mixer. A partition is laid on a first fixing sheet, a portion laid on a second fixing sheet, and the remainder discharged to the second mixer. In the second mixer, foam is added and the formed slurry is laid on the unformed slurry on the first fixing sheet. The unformed slurry in the second fixing sheen is brought to the formed slurry to join the product.

Abstract: Hot gas is introduced into a fluidised bed of granular material, for example gypsum, contained in a vessel 10 having a grinding device or mill 11 in its lower region, which may comprise grinding rollers 15 cooperating with a table 17 on the base of the vessel. The gas may be supplied through a tube 20 passing down through the vessel, while raw material is fed into the bed, preferably by a feed screw 34. The ground product is discharged from the bed by an overflow 28 which determines the level of the bed.

Abstract: The invention provides a method of making gypsum products such as plasterboard from foamed gypsum plaster slurry. The method uses a first mixing chamber 10 containing a high speed rotor 14 and inlets 18, 19 for gypsum plaster and water. The initial dispersion of gypsum plaster and water foamed in the first chamber passes directly and continuously into a second chamber 25 containing a low speed rotor 29. Preformed foam is introduced into the second chamber through an inlet 33, and the foamed slurry product leaves the second chamber through an outlet 34, to be formed into plasterboard.

Abstract: The invention provides apparatus for use in the preparation of gypsum products such as plasterboard from foamed gypsum plaster slurry. The apparatus comprises a first mixing chamber 10 containing a high speed rotor 14 and inlets 18, 19 for gypsum plaster and water. The initial dispersion of gypsum plaster and water foamed in the first chamber passes directly and continuously into a second chamber 25 containing a low speed rotor 29. Preformed foam is introduced into the second chamber through an inlet 33, and the foamed slurry product leaves the second chamber through an outlet 34, to be formed into plasterboard.

Abstract: A wall or lining structure for shafts, ducts or barriers comprises panel members (11) supported by studs (10) having spaced parallel flanges (13,15). The panels are held against the inner surface of at least one flange by an independent spacer member (14) having different cross-sectional dimensions in different directions. Different numbers of thicknesses of the panel members can be accommodated between the flanges of identical studs by varying the orientation of identical spacer members relative to the studs.

Abstract: In a method and apparatus for the heat treatment of gypsum or like heat material, in which the material is heated in a vessel by indirect heat exchange with hot gas produced by the fluidized combustion of a fuel, material is fed into a first fluidized bed of the material. Partially treated material is removed from the lower region of the first bed and introduced with the assistance of compressed air into the upper region of a second fluidized bed. Treated material is removed from the second bed. The beds of material are both fluidized by means of the introduction of the hot gas product of the fluidized combustion bed, further heating the beds. The first bed may be operated at a lower temperature than the second bed, although both beds may receive substantially the same heat input.

Abstract: A flooring system which enables floors of enhanced sound insulation to be produced with minimal raising of floor level above that for a simple floor comprises inverted channel section floor supports mounted longitudinally on joists and having outwardly directed flanges. Sound isolating material is interposed between the floor supports and the joists, panel members are laid between the floor support flanges, and floor decking extends over the panel members and is secured to the floor supports. Where the floor supports, which may be of a standard width, are substantially wider than the joists, locating clips may be interposed between the supports of the joists. The system is advantageously used in conjunction with a resiliently supported ceiling.

Abstract: The invention relates to building components, for example studs for supporting wall boards, made of a plaster-resin mixture, with a fibrous sheet embedded near the surface. Components according to the invention have excellent fire-resistant properties. Such components can be made by, for example, introducing a plaster-resin slurry into a mould lined with fibrous sheets, and allowing the slurry to set, or they may be made continuously by, for example, passing the slurry and sheets through one or more suitably profiled conveyors, vibration being employed to cause the slurry to penetrate through the sheets. Such components may be of H, C or U section for use as, for example, studs. They can also be used, for example, as ceiling panels or acoustic tiles, for which purposes they may be of hollow or channel form, and be filled with fibrous or other porous material.

Abstract: An apparatus for calcining a granular or powdered mineral, more specifically hydrated calcium sulphate, comprising a vessel the side wall or walls of which slope inwardly toward a bottom of small cross-sectional area, as compared with an upper region of the vessel, and provided with a downwardly extending heating tube connectable in an upper portion to a gas source and an opening in a lower portion into the interior of the vessel adjacent to the bottom thereof, the arrangement being such that, in use, hot gases issuing from the lower portion of the heating tube will mix and heat substantially all the contents of the vessel.

Abstract: In the manufacture of cementitious board by depositing a slurry of hydraulic cementitious material, commonly gypsum plaster, between two facing sheets and forming it to the desired width and thickness prior to setting, the formation of voids in the core, due to air trapped in the slurry is avoided by vibrating the lower sheet (10) after the slurry (15) has been deposited on it, usually before the upper sheet (14) contacts the slurry, and subsequently vibrating the upper sheet when it comes into contact with the mass of cementitious slurry. The vibration of the lower sheet, for example by rotating polygonal shaft (20), causes bubbles of unwanted trapped air to rise through the slurry towards the upper surface and the accumulated bubbles are then broken by the vibration of the upper sheet, which may be accomplished by a second rotating shaft (21), before they become incorporated into the formed board as voids.

Abstract: A building board comprises a core 31 of set cementitious material, such as gypsum, faced on at least one side by a fabric or web 33 of mineral fibres embedded in the face of the core and a continuous film 32 of the cementitious material having a higher density and lower porosity than the core extending over the outer face of the fabric. The film may have a smooth surface or a desired textured or figured surface. The preferred fabric or web 33 is a non-woven glass fibre tissue and it is preferred that a continuous film 32 of gypsum at the surface should not exceed 2 mm in thickness. The board is made by bringing the fabric or web into contact with the respective face of a layer of an aqueous slurry of gypsum plaster or other cementitious material, and vibrating the layer of slurry in contact with the fabric or web until slurry penetrates the web and the latter is completely embedded.