The invention pertains to a process for modifying gypsum, wherein a continuous feed of raw gypsum is provided; the water content of the raw gypsum is determined in the continuous feed by near infrared spectroscopy (NIR) measurement; the raw gypsum is calcined in a calcination unit at a fire rate to remove water from the raw gypsum and to obtain a continuous feed of calcined gypsum having a water content within a selected range; a water content of the calcined gypsum is determined by near infrared spectroscopy, and the fire rate is adjusted based on the water content of the raw gypsum and of the calcined gypsum. Further, the invention pertains to an apparatus for performing said process.

The invention pertains to a process for modifying gypsum, wherein a continuous feed of raw gypsum is provided; the water content of the raw gypsum is determined in the continuous feed by near infrared spectroscopy (NIR) measurement; the raw gypsum is calcined in a calcination unit at a fire rate to remove water from the raw gypsum and to obtain a continuous feed of calcined gypsum having a water content within a selected range; a water content of the calcined gypsum is determined by near infrared spectroscopy, and the fire rate is adjusted based on the water content of the raw gypsum and of the calcined gypsum.

Further, the invention pertains to an apparatus for performing said process.

The invention pertains to a process for modifying gypsum, wherein a continuous feed of raw gypsum is provided; the water content of the raw gypsum is determined in the continuous feed by near infrared spectroscopy (NIR) measurement; the raw gypsum is calcined in a calcination unit at a fire rate to remove water from the raw gypsum and to obtain a continuous feed of calcined gypsum having a water content within a selected range; a water content of the calcined gypsum is determined by near infrared spectroscopy, and the fire rate is adjusted based on the water content of the raw gypsum and of the calcined gypsum.

Further, the invention pertains to an apparatus for performing said process.

Perlite-free, lightweight setting-type joint compounds which comprise calcium sulfate hemihydrate with a dry density of less than 50 lb/ft.sup.3, a foaming agent having a HLB value of at least 10 and preferably comprising an alkylbenzene sulfonic acid having a linear alkyl chain containing 8 to 14 carbons and/or a salt thereof, and a combination of rheology modifiers. Methods for building wallboard assemblies and methods for wall patch and repair projects that include applying the perlite-free, lightweight setting-type joint compounds to a substrate.

Perlite-free, lightweight setting-type joint compounds which comprise calcium sulfate hemihydrate with a dry density of less than 50 lb/ft.sup.3, a foaming agent having a HLB value of at least 10 and preferably comprising an alkylbenzene sulfonic acid having a linear alkyl chain containing 8 to 14 carbons and/or a salt thereof, and a combination of rheology modifiers. Methods for building wallboard assemblies and methods for wall patch and repair projects that include applying the perlite-free, lightweight setting-type joint compounds to a substrate.

An apparatus for calcination of gypsum includes a gypsum calciner having an interior wall surface with a circular or annular configuration as seen in its plan view, and a tubular combustor positioned at a center part of a body of the calciner. Raw gypsum is calcined or dehydrated by a high temperature gas spouting flow (Hg) ejected from a lower portion of the combustor. The calciner has a stationary-vane-type or movable-vane-type auxiliary device, which circumferentially energizes the raw gypsum in the vicinity of the interior wall surface toward a circumferential direction of the calciner. The auxiliary device has a plurality of stationary vanes circumferentially arranged in an outer peripheral zone of a lower portion of the combustor and spaced apart from each other at an angular interval, or an agitator extending through a conical or inner circumferential surface defined by the interior wall surface.

The present invention is directed to a gypsum panel with reduced calcination and a method of making such gypsum panel. For instance, in one embodiment, the gypsum panel comprises a gypsum core and a first facing material and a second facing material sandwiching the gypsum core, wherein the gypsum core includes gypsum and a calcination inhibitor. The methods of the present invention are directed to making the aforementioned gypsum panels.

A method of producing a gypsum binder, the method including dehydrating of gypsum raw material lumps by heating in a gaseous medium with further drying, cooling, and milling stages, wherein the heating gypsum raw material lumps is performed either by: (i) placing the lumps in a heating medium set to a temperature exceeding the temperature under which dehydration and formation of gypsum -hemihydrate occurs; and/or (ii) placing the lumps in a heating medium having a high rate of temperature increase such that a temperature higher than the temperature under which dehydration and formation of gypsum -hemihydrate occurs is reached; wherein a heating time is selected sufficient for completion of the process of gypsum -modification formation within the gypsum lumps, and wherein the heating is performed under atmospheric pressure through lump surface.

A method of producing a gypsum binder, the method including dehydrating of gypsum raw material lumps by heating in a gaseous medium with further drying, cooling, and milling stages, wherein the heating gypsum raw material lumps is performed either by: (i) placing the lumps in a heating medium set to a temperature exceeding the temperature under which dehydration and formation of gypsum -hemihydrate occurs; and/or (ii) placing the lumps in a heating medium having a high rate of temperature increase such that a temperature higher than the temperature under which dehydration and formation of gypsum -hemihydrate occurs is reached; wherein a heating time is selected sufficient for completion of the process of gypsum -modification formation within the gypsum lumps, and wherein the heating is performed under atmospheric pressure through lump surface.

Disclosed is an apparatus and method for capturing the hot humid gases from a gypsum board dryer and utilizing those gases in the production of a synthetic gas (referred to as syngas). The syngas produced can then be utilized within a gypsum board plant to reduce the amount of natural gas needed. The method utilizes the heated water vapor (H.sub.2O) and carbon dioxide (CO.sub.2) found within the flue gas of a board dryer. The H.sub.2O and CO.sub.2 are used in a gasification process to yield the syngas.