A fluidized-bed-type apparatus and method for treating gypsum, which activates or improves fluidity of gypsum powder to promote an effect of treatment of gypsum, such as modification or homogenization of the gypsum powder. The apparatus for treating gypsum includes a reactor vessel, a conditioned air supply port, a horizontal partition wall and a plurality of stationary vanes. The wall allows a conditioned air flow to flow upward into a reaction region. The vanes are arranged at an angular interval in a circumferential direction. A fluidized bed of calcined gypsum is provided in the vessel. The vane deflects the conditioned air flow flowing upward into the reaction region, toward a radially outward and circumferential direction of the reaction region. The calcined gypsum makes a saltational fluid motion or saltational movement in the vessel with the air flow.

Beads of materials such as activated alumina, zeolite and silica gel, are used as chloride salt absorbers. The beads are mixed with high-salt gypsum. After mixing for a short time, the mixtures are dried, and the beads and the powder are separated by using a sieve or other physical separation device resulting in a low-salt gypsum which can be used as a gypsum source to make gypsum wallboard.

A method for continuously forming gypsum-based panels of high fixing strength comprises the steps of: •forming a mixture comprising stucco, non-pregelatinized migratory starch, glass fibre, fluidizer and water; •casting the mixture in a continuous band; •maintaining the band under conditions sufficient for the stucco to form an interlocking matrix of set gypsum; •cutting the band to form one or more wet panel precursors; and •drying the wet panel precursor to form one or more gypsum-based panels. •The weight ratio of water to stucco in the mixture is less than 0.7; •the stucco is present in the mixture in an amount of over 60 wt % relative to the total solids content of the mixture; •the starch is present in the mixture in an amount of over 3 wt % relative to the stucco; •the glass fibre is present in the mixture in an amount of over 1 wt % relative to the stucco; •the fluidizer is present in the mixture in an amount of at least 0.1 wt % relative to the stucco; and the density of the gypsum-based panel is greater than 700 kg/m.

Beads of materials such as activated alumina, zeolite and silica gel, are used as chloride salt absorbers. The beads are mixed with high-salt gypsum. After mixing for a short time, the mixtures are dried, and the beads and the powder are separated by using a sieve or other physical separation device resulting in a low-salt gypsum which can be used as a gypsum source to make gypsum wallboard.

Provided are a gypsum set accelerator wherein the gypsum set accelerator is a dry-milled mixture comprising calcium sulfate dihydrate co-ground with one or more of the following: a polycarboxylic ether (PCE) and/or a sulfonated melamine polycondensate (SMP), gypsum slurries formulated with the gypsum set accelerator and methods for producing the gypsum set accelerator and manufacturing gypsum products with the gypsum set accelerator.

The present invention is directed to a construction chemical composition for the preparation of gypsum articles, said construction chemical composition comprising fine calcium sulfate and a dispersant being a polyarylether. Further the present invention is directed to a process for preparing said construction chemical composition as well as an article comprising said construction chemical composition.

The present invention is directed to a construction chemical composition for the preparation of gypsum articles, said construction chemical composition comprising fine calcium sulfate and a dispersant being a polyarylether. Further the present invention is directed to a process for preparing said construction chemical composition as well as an article comprising said construction chemical composition.

A multitubular rotary heat exchanger has a stationary shielding unit. The shielding unit is positioned in close proximity to a tube plate outside a heating or cooling region. A stationary surface of the shielding unit is positioned in opposition to and in close proximity to an end opening of a heat transfer tube moving in an upper zone of the heating or cooling region, thereby transiently reducing or restricting the flow rate of the thermal medium fluid flowing through the heat transfer tube moving in the upper zone.

A system for conditioning stucco particulate material includes a vessel having separation chamber in communication with a holding chamber having a holding volume therein. The conditioning system includes the holding volume sufficient to condition the stucco particulate material therein and/or a control system configured to delay discharge of the stucco particulate material from the holding chamber. The system for conditioning stucco particulate material is configured to increase residence time of the stucco particulate material in the holding chamber to promote calcining conditioning therein.

A fluidized-bed-type apparatus and method for treating gypsum, which activates or improves fluidity of gypsum powder to promote an effect of treatment of gypsum, such as modification or homogenization of the gypsum powder. The apparatus for treating gypsum includes a reactor vessel, a conditioned air supply port, a horizontal partition wall and a plurality of stationary vanes. The wall allows a conditioned air flow to flow upward into a reaction region. The vanes are arranged at an angular interval in a circumferential direction. A fluidized bed of calcined gypsum is provided in the vessel. The vane deflects the conditioned air flow flowing upward into the reaction region, toward a radially outward and circumferential direction of the reaction region. The calcined gypsum makes a saltational fluid motion or saltational movement in the vessel with the air flow.