Abstract: A suspended grid subceiling and panel units therefor having the appearance of a continuous expanse of decorative light-transmitting block masonry. In a preferred embodiment, the panels units are assemblies of an opaque subgrid of rails and cross rails and translucent subpanels simulating the mortar lines and faces of glass block. The undersides of the grid main runners and cross runners are similar in shape to the subgrid rails and cross rails and have a surface finish matching the color and texture of the subgrid undersides.

Abstract: A setting accelerator for calcined gypsum plaster and a process for its preparation are disclosed. The accelerator comprises finely ground calcium sulfate dihydrate having composite coatings on the particles of firstly a calcination inhibiting material such as sugar and secondly a coating of aluminum sulfate hydrate. The accelerator is particularly useful in the formation of gypsum wallboard.

Abstract: A lightweight cast acoustical material requiring less drying time and energy is obtained by lightly cooking an aqueous slurry of starch, cooling it to about less than 140.degree. F., whipping air into it, adding granulated mineral wool with thorough mixing to form a foam, casting the resultant wet foamed pulp into a form and drying the formed pulp to an acoustical product. The web pulp has an about 40 weight % reduction in water content, resulting in considerable savings in drying time and energy.

Abstract: Increased fire resistant gypsum board core formulations and plaster fireproofing formulations are provided by incorporating calcium sulfate anhydrite into the formulations. Particularly fire resistant effects are achieved with a fibrous form of calcium sulfate anhydrite, and with blends of calcium sulfate anhydrite II in particulate or fibrous form. Optionally, the formulations may contain either small amounts of textile glass fiber, wollastonite or vermiculite.

Abstract: High strength and high density wood fiberboard is formed by treating the wood fiber source material with a highly alkaline solution, such as sodium hydroxide solution, before interfelting the fibers into a loose mat. The wood source material may be treated after refining the material into fibers, but preferably, the wood source material is treated before fibrillation. Further, wood fiber source material may be partially neutralized before felting without substantial change in the resulting densities and strengths.

Abstract: Blown mineral wool fibers are introduced into slurries (such as gypsum board core formulations and steel column fireproofing plaster formulations) by first blending and coating the blown mineral wool with a powdered calcium sulfate to produce a light, open nodulated effect. When mixed into aqueous calcined gypsum slurries, the nodules open up, thoroughly dispersing the mineral wool--calcium sulfate blend in the aqueous slurry and contributing fire resistant properties to the set gypsum product.

Abstract: A process for adsorbing sulfur dioxide from a gas comprising contacting a gas containing SO.sub.2, such as a flue gas, with about stoichiometric amounts of a specially prepared calcium oxide so that substantially all of the sulfur dioxide content is reacted throughout the calcium oxide particle to form a calcium sulfate reaction product. The useful calcium oxide particles comprise a highly voided skeletal structure of very large surface area and large pore volume with numerous macro pores. Such particles are obtained by flash calcining sand-size grains of calcium carbonate, such as aragonite, calcite or dolomite.

Abstract: Wet chemical gypsum cake may be directly fed to a continuous kettle calciner to produce a stucco having lowered dispersed consistency. Pre-drying of the chemical gypsum is eliminated and the thus produced stucco may be used in the formulation of building plasters and in gypsum wallboard manufacture that will use less fuel for drying excess gauging water.

Abstract: Apparatus for making an acoustical tile having a pattern of raised portions and portions in relief on the tile surface is provided by a hollow embossing roll containing the pattern in reverse and interstices communicating from the surface of the roll into the hollow interior of the roll. In operation the roll contacts the formable, acoustical tile fiber composition pulp with sufficient force as to disspell the pulp, vent air that may be between the roll and the pulp surface through the roll, and produce a reversed pattern of the roll upon the pulp surface, then releasing the pulp from the surface of the roll by rotation of the roll.

Abstract: Expanded perlite is produced while simultaneously or substantially simultaneously coating the expanded perlite with an hydrophobic coating material by passing the expanded perlite and heated expander exhaust gases from the expansion chamber through a cooling and coating chamber provided with spray nozzles to provide a stream of atomized coating material onto the expanded perlite, while upstream thereof an air intake and temperature sensor are situated to control the air flow and temperature in the cooling and coating chamber so as to provide proper curing temperatures for the coating material upon the expanded perlite before it is separated from the exhaust gases.

Abstract: Mineral filler materials are provided with improved hydrophobic coatings by pressure coating of porous minerals using steam as a carrier for the coating material. Thereby more complete sealing of fissures and cracks in the porous filler materials' surface is provided, resulting in very water-resistant coated particles useful in filling polymeric substrates such as paints, plastics and joint compounds.

Abstract: A method for making acoustical tile having a pattern of raised portions and portions in relief on the tile surface is provided by contacting deformable, acoustical tile fiber composition pulp with a hollow embossing roll containing the pattern in reverse and interstices communicating from the surface of the roll into the hollow interior of the roll; pressing the roll against the deformable pulp with sufficient force as to dispel the pulp; vent air, between the roll and the pulp surface, through the roll and produce the reversed pattern of the roll upon the pulp surface; and releasing the pulp from the surface of the roll by rotation of the roll.

Abstract: Solidification of colloidal argillaceous matter in essentially non-settling, aqueous slime media into a solid stable matrix is accomplished by mixing such slime with a hydratable calcium sulfate and hydrating to form an interlocking strength bearing matrix. The method is particularly useful for coalescing phosphatic clay slimes with hydratable calcium sulfate prepared from the co-produced waste phosphogypsum.

Abstract: A wet process for producing phosphoric acid and phosphoanhydrite by acidulation of phosphate rock with a phosphoric acid/sulfuric acid mixture containing a very high recycle content of small sized anhydrite seed crystals. A strong phosphoric acid is obtained having a concentration of at least about 35% P.sub.2 O.sub.5. Further, the phosphoanhydrite may be readily converted to an industrially usable gypsum product.

Abstract: A process for rapidly dewatering and drying calcium sulfate hemihydrate in a centrifuging and flash drying operation by ejecting the wet solids from the centrifuge bowl directly into the flash dryer's high velocity, high volume, heated air stream.

Abstract: Substrates such as metal, plastic, hardboard and plywood may be coated with a translucent film of a filled acrylic resin so that a decorative stain may be applied. The filler in the acrylic resin is an extender pigment having a mean particle size of from about 5 to about 7 microns.

Abstract: A wet process for producing phosphoric acid and phosphohemihydrate by acidulation of phosphate rock. A strong phosphoric acid is obtained with concomitant production of an improved calcium sulfate that is extremely low in radioactivity by operation in Region II for shorter time so as to produce small sized hemihydrate particles, then hydration of a substantial proportion but less than all of the hemihydrate to coarse gypsum substantially free of radioactivity in a dilute acidic aqueous slurry at a temperature and P.sub.2 O.sub.5 concentration selected so as to be within Region I of FIG. 1 and having a substantial weight proportion of coarser gypsum particles that are substantially free of radioactivity.

Abstract: A method of disposing of wastes, especially wastes containing radioactive or toxic substances, such as the wastes generated in the water associated with nuclear power production is described. A feature of the invention is to incorporate the waste into a hardenable setting mass when mixed with water, comprising calcium sulfate hemihydrate, water soluble melamine formaldehyde resin which when cured is hydrophobic, and a cross-linking agent for curing the resin.