SU69597A1 - The method of obtaining gypsum in a binder - Google Patents

Description

Production of high-strength gypsum type KINA cement using the most common method involves pre-firing the gypsum stone into semi-aquatic gypsum, impregnating it with alum solution and drying, after which the material is subjected to secondary calcination at a temperature of up to 800 °. After firing, the material is milled and shuttered either with water or with an aqueous solution of alum.

Another method of producing this type of gypsum involves saturating the gypsum stone with a solution of alum, drying it and firing it once at high temperature, followed by grinding and mixing with either water (ENT plaster) or an aqueous solution of alum.

The most advanced method of producing KINA cement is calcining gypsum to complete dehydration, treating the dehydrated product with a 10% alum solution, secondary calcination at a high temperature, grinding the finished product and mixing eso, as in previous cases.

All these methods have one drawback. As you know, one of

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features of the production process is to give the material a snow-white color, bringing the product in whiteness to the standard - barium sulphate. For this, in all herds of production, it is necessary to sort out contaminated pieces, both burned before impregnation and after impregnation with alum and secondary roasting.

In addition, significant losses occur during the impregnation of the semi-finished product, drying it, and especially during the secondary calcination of the already impregnated product.

The second method mentioned above is generally associated with great difficulties, since it is difficult to imbue a dense stone from the first time with the necessary amount of alum, and even more so to obtain a uniformly impregnated stone. It is necessary to resort to repeated impregnation and re-drying of the material.

In all cases, with improper firing, all products are lost.

The authors have developed a new method for the production of high-strength gypsum-type cement KINA, which is that the gypsum stone burns

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prior to anhydrous modification, then impregnated with boiling aqueous solution of aluminum-potassium alum for about 40 minutes, after which the material is dried until the hygroscopic moisture is removed (at a temperature of about 120 °) and then ground.

Before use, the powder is water shut.

The calcined gypsum is sorted before impregnation. All pieces of KINA unsuitable for cement and contaminated with M, eirio4b are used as anhydrite-cement or as a filler in paper production, etc. According to the authors, product losses in production according to the proposed method are minimized, and the resulting material has 1.5 times

larger physico-mechanical indicators than the similar one obtained with the usual method of production. The latter is explained by the authors of a more complete and uniform impregnation of the intermediate product with alum, as well as the fact that alum is not exposed to high temperature.

Subject invention

The method of obtaining gypsum in a live by firing raw gypsum to anhydrous modification and impregnation with alum solution, characterized in that the impregnation is carried out in boiling aqueous solution of alum, after which the material is subjected to substance at a temperature of about 120 ° and the subsequent grinding by known techniques.