Abstract: An improved "lump" process for producing alpha gypsum, calcium sulfate hemihydrate, from natural gypsum rock of the type wherein lumps of gypsum rock particles (a minimum of about 1/2 inch or 1.3 cm. in size) are calcined to low water-demand alpha hemihydrate by autoclaving in a saturated steam atmosphere, quickly dried and pulverized is disclosed. The improvement allows the thorough processing of natural gypsum as large sized particles or containing considerable selenite and includes the steps of initiating calcination without crystal habit modifier and, after hemihydrate formation has commenced, adding crystal habit modifier and completing calcination under increased steam pressure.

Abstract: An additive for reducing the amount of water necessary in forming a pourable aqueous calcined gypsum slurry, the additive comprising a high potassium salt of a condensation product of naphthalene and sulfonic acid having a molecular weight between about 300 and 3,000. Aqueous plaster slurries containing the additive are pourable, moldable and castable with much less excess water than ordinarily required, resulting in dried cast products of increased strength and other physical property benefits.

Abstract: A process is described for highly efficient recovery of phosphate values from a wide range of phosphate rock including low grade phosphate rock material by leaching with a dilute sulfuric acid and precipitating phosphate values as dicalcium phosphate. Water savings are accomplished in the process by the use of sea water instead of fresh water.

Abstract: Perfluoro compound-epoxy resin compositions manifesting oil and soil resistance said compositions comprising an epoxy resin and a block copolymer of the type [ABA].sub.n wherein A is a perfluoro group having from 8 to 10 carbon atoms, B is a low molecular weight functionality reactive with the epoxy resin and n is from 1 to about 5.