Abstract: A method of decreasing the expansion temperature and improving the expansion characteristics of vermiculite ore comprising subjecting vermiculite ore containing interlamellar cations to a potassium nitrate solution for a time interval sufficient to ion-exchange interlamellar cations within said ore with potassium ions. Subsequent to this ion exchange the low temperature expandable vermiculite may be expanded by heating in an oven, or incorporated in an intumescent material and heat expanded in situ, or expanded by other heating means. An intumescent sheet is provided which may be used for mounting automotive catalytic converter monoliths comprising an unexpanded vermiculite produced by the method of the invention; an inorganic fibrous material; and a binder.

Abstract: A method of decreasing the expansion temperature and improving the expansion characteristics of vermiculite ore comprising subjecting vermiculite ore containing interlamellar cations to a potassium nitrate solution for a time interval sufficient to ion-exchange interlamellar cations within said ore with potassium ions. Subsequent to this ion exchange the low temperature expandable vermiculite may be expanded by heating in an oven, or incorporated in an intumescent material and heat expanded in situ, or expanded by other heating means. An intumescent sheet is provided which may be used for mounting automotive catalytic converter monoliths comprising an unexpanded vermiculite produced by the method of the invention; an inorganic fibrous material; and a binder.

Abstract: Stable vermiculite dispersions which are substantially free of settling and a method of preparing same are provided. The dispersions are obtained by treating the vermiculite platelets of which the dispersion is comprised with citrate anion. The citrate anion functions as a swelling agent for the vermiculite and enhances the rate and extent of swelling in an aqueous medium. The swollen vermiculite is delaminated by shearing to provide the inventive dispersions, which comprise a suspension of the delaminated platelets and citrate anion.

Abstract: A process is described for the formation of fibrous insoluble calcium sulfate anhydrite, the fibers thereof having specified dimensions. A dilute aqueous suspension of gypsum and, if desired, a crystal habit modifier suitable for the formation of fibrous calcium sulfate hemihydrate, is first formed. The gypsum in this suspension is then converted to the fibrous hemihydrate by reaction in the presence of saturated steam at 120.degree. C to 155.degree. C for 0.5 to 2.5 hours, thereby forming fibrous calcium sulfate hemihydrate of the desired dimensions. The fibrous hemihydrate is thereafter calcined at 500.degree. C to 750.degree. C for 0.5 to 3.0 hours to convert the fibrous hemihydrate to fibrous insoluble calcium sulfate anhydrite having substantially the same crystalline shape and dimensions.

Abstract: A process is described for the formation of fibrous calcium sulfate hemihydrate, the fibers thereof having specified dimensions, wherein a dilute aqueous suspension of gypsum and, if desired, a crystal habit modifier is first formed. The gypsum in the suspension is then converted into fibrous hemihydrate by reaction in the presence of saturated steam at 120.degree. to 155.degree.C for 0.5 to 2.5 hours.