Abstract: A wet pulp of mineral fibers or the like is forced between a pulp carrier and a corrugated texturing skid inclined toward the downstream end of a moving slab of the pulp. The corrugations of the skid are co-directional with the machine direction of the conveyor belt that transports the pulp under and beyond the skid.

Abstract: A method for the manufacture of very low density mineral wool structural panels on a moving foraminous support wire by frothing a dilute aqueous dispersion of mineral wool is disclosed. The forth, a mass of delicate, non-resilient and non-uniform bubbles among the entangled mineral wool fibers readily breaks, is stripped of water and dried without substantial loss of the highly open, porous structural configuration by a first controlled rate of maturation dewatering followed by brief pulses of high vacuum. Then the open structure is rapidly stripped of remaining water and dried by passing high volumes of heated dry air through the structure with continued vacuum. The drainage water may be recycled in the process to maintain a low level of binder and any frothing aid additions.

Abstract: In a method and apparatus for calcining calcium sulphate dihydrate or like heat sensitive material, in which a bed of the material is heated in a vessel (41) by the direct introduction of a hot gas through a tube (21) extending downwardly into the bed, the proportion of insoluble anhydrite (II) in the product is reduced by lowering the temperature of the hot gas before it contacts the material of the bed. This is done by indirect heat exchange through the wall of the tube 21 with a relatively cool substance, for example, powdered gypsum or recycled exhaust gases, in an outer tube (26). The cooling material in the outer tube contacts the material in the bed before the latter is contacted by the hot gas.

Abstract: A paper cover sheet particularly designed for use as the face sheet in the manufacture of gypsum wallboard, the face sheet having a base formed of a plurality of filler plies formed of recycled paper comprised of clean hard stocks such as kraft and boxboard cuttings, and being free of topliner plies containing flyleaf furnish, the base having a coating on the face surface thereof comprising a light colored mineral filler and a binder. The coating provides a light color to the face surface generally termed "manila". The elimination of the topliner plies results in a paper of excellent strength and porosity.

Abstract: This invention comprises a suspended ceiling grid system having an adjustable compression strut installed between the grid members of the system and the building or construction superstructure which lies in a plane above the suspended ceiling. The adjustable compression strut stabilizes the ceiling system and prevents upward movement of the system such as might occur during a seismic shock or earthquake tremor. The compression strut comprises two co-axial, telescoping cylindrical strut members having a spring clip attached to the inner end of the inner strut member that allows the strut to be extended but not retracted. The compression strut is installed by simply holding it in position between the suspended ceiling grid and the superstructure and then extending the strut members until they are locked in place by the action of the spring clip.

Abstract: An apparatus for texturing the surface of wet cast plastic acoustical composition during manufacture of acoustical tiles by use of spinning air rolls. In the apparatus, at least one hollow cylindrical roll that is perforated in a random manner is suspended over the surface of wet cast plastic acoustical composition, the roll being driven by a motor. The interior of the roll is preferably provided with a perforated air tube or pipeline, from which issues uniform air pressurization of the spinning roll vessel. By providing differential speed of the roll in contrast to the line speed of the wet plastic composition and different air pressurization of the roll, a wide variety of textures may be produced on the surface of the wet plastic acoustical composition.

Abstract: The invention concerns an improved method of calcining gypsum in which non-reactive hot gas is passed into contact with the gypsum from a source through a plurality of tubes extending downwardly into the gypsum. The invention also contemplates an improved apparatus which comprises a calcining kettle and a plurality of tubes connected to a common source of non-reactive hot gas and extending downwardly into the kettle and having openings in their lower regions to release the hot gas into the contents of the kettle. The invention provides a method and apparatus which produces gypsum plaster of improved quality and with less insoluble anhydrite.

Abstract: Gingivitis and related periodontal problems of the gingival tissues may be treated with a dental hygiene composition comprising an effective amount of a calcium sulfate compound such as calcium sulfate hemihydrate. Preferred compositions comprise mouthwashes and oral rinses containing about 5-90% by weight of calcium sulfate hemihydrate, a liquid carrier such as water, a humectant and an alcohol.

Abstract: A paper particularly adapted for use as cover sheets in the production of gypsum wallboard, the paper having improved porosity and strength to permit better drainage and more rapid drying in the production of the paper to permit less fiber to be utilized, and to permit less heat to be utilized in drying the paper, providing for production of superior gypsum board. The paper comprises in weight percent:(A) fibers having a fiber freeness of from about 350 to 550 ml. Canadian Standard Freeness,(B) a buffering agent in an amount from about 0.25 to about 10%,(C) a neutral sizing agent in an effective amount to prevent water penetration, and(D) a cationic starch.In a preferred embodiment the paper is treated with a neutral internal sizing agent during its formation, and subsequently treated with a surface sizing agent after formation of the paper, in order to provide certain properties including better adhesion to the gypsum core.

Abstract: This invention relates to the manufacture of hydroxylapatite in a through-solution process wherein monobasic calcium phosphate is reacted with a calcium hydroxide solution. In a preferred embodiment, an acidic premix is formed by reacting phosphoric acid and calcium hydroxide with high shear agitation in a first stage, and thereafter reacting the acidic premix with a saturated solution of calcium hydroxide also under high shear agitation in a second stage. The second stage reaction is carried out in an alkaline solution by carefully metering the acid premix into the calcium hydroxide solution whereby the pH of the solution is maintained above 11 until the reaction is near completion. It is particularly preferred to use a stoichiometric portion of calcium hydroxide in carrying out the reactions. After the hydroxylapatite precipitate is recovered, it may be sintered at a temperature between about 700.degree. C. and 1100.degree. C. for about 5 to 30 minutes to form a crystalline hydroxylapatite.

Abstract: A tabular variety of acicular gypsum crystal filler is prepared by hydrating calcium sulfate dihydrate particles in a seeded continuously stirred reactor at a low level of super-saturation to obtain crystals having an aspect ratio of about 100:10:1 and average length in the longest dimension of about 100-450 micrometers. For the manufacture of paper, the obtained tabular crystal slurry may be directly added to the paper pulp before web formation to obtain a filled paper having high filler retention.

Abstract: A shower door mounted on rails for movement thereon and having a lower guide assembly which is free-floating and which comprises a flange retained in a lower sill track slot and having the other end hingedly mounted on a flange of the shower door.

Abstract: A belt press for dewatering slurries is described having a frame designed to minimize the time, effort and frame stress heretofore encountered in the replacement of endless belts, said press comprising a rigid frame comprised of essentially parallel horizontal and vertical members supporting a plurality of laterally oriented longitudinal rolls upon which a pair of endless flat foraminous belts pass in a serpentine path with dewatered material sandwiched therebetween. The frame is equipped with vertical legs having removable spacers on one side and corresponding elastomeric hinges mounted with pre-stressed bolts, and alignment pins on the other side. Jack means positionable between the sides of the frame, co-operate with the pre-stressed bolts to permit removal of the frame spacers and extraction of the endless belts through the resulting gaps in the vertical legs.

Abstract: An industrial waste anaerobic digester is disclosed having separate sections therein, in which the acid forming and gas forming phases of the digestion process can occur separately under conditions optimized for each phase. A rotating biological contactor is provided in each section for increasing the liquid/gas interface to facilitate the anaerobic reaction. A series of partitions is provided in each section to create zones in which the waste concentration is extremely high and on which the biota can react at maximal reaction rates. The CO.sub.2 produced in the acid forming phase is used in both acid and gas forming sections to mix and achieve pH adjustment, and the methane can be used in the gas forming sections for mixing. A thermophilic chamber in the center of the tank is surrounded by the mesophyllic chamber to minimize and utilize conductive heat loss.