Process for producing calcined gypsum and gypsum board

Abstract

The invention provides a process for calcined-gypsum production which attains a reduction in the amount of water to be mixed and does not prolong setting time. A raw-material gypsum is calcined after a carboxylic acid is incorporated thereinto, whereby calcined gypsum can be obtained which necessitates a smaller amount of water to be mixed therewith and needs no prolonged setting time. Even when recycled gypsum, which leads to an increase in the amount of water to be mixed, is used in a large amount as a raw material for gypsum, the calcined gypsum produced by the process is reduced in the amount of water to be mixed therewith and needs no prolonged setting time. Consequently, ordinary gypsum boards can be produced without lowering the productivity thereof.

Description

technical field [0001] The present invention relates to a method for producing plaster of paris by firing raw gypsum and a method for producing plasterboard using the plaster of paris. Background technique [0002] Plaster of paris can be produced by burning raw material gypsum such as chemical gypsum and natural gypsum alone or in combination, and transferring the raw material gypsum which is mainly dihydrate gypsum to mainly hemihydrate gypsum. [0003] Since the plaster obtained by the above method can become a dihydrate and solidify quickly when adding an appropriate amount of water and making it into a slurry, it can be used as a raw material for various gypsum products, such as gypsum boards. [0004] Gypsum board is a plate-shaped body in which base paper for gypsum board is covered on a core mainly composed of dihydrate gypsum. Plaster of paris, adhesion promoters, hardening accelerators, foam for weight reduction, and other additives are used in the manufacture, and...

AI Technical Summary

Problems solved by technology

Although this method can reduce the amount of water mixed in the plaster of paris, and can reduce the drying energy required, but due to the prolonged setting time, the manufacturing speed of the gypsum board is reduced. In order to avoid delaying the manufacturing speed of the gypsum board, a large amount of setting accelerator can be used , but this in turn leads to the decline of various physical properties of gypsum board

Moreover, since this method requires a new water treatment device and a drier for drying the residual free water of the water-treated plaster, it leads to problems of complicated equipment, increased installation costs, and increased cost of producing plaster.

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