RU1784602C - Process for producing gypsum binder - Google Patents

Abstract

The invention can be used in the production of gypsum binders, obtained by heat treatment of a gypsum stone with subsequent grinding. The essence of the invention is a method for producing gypsum binders, including heat treatment of gypsum stone and its grinding, provides for grinding in the presence of superplasticizer C-3 at a temperature not less than 75-80 ° C. Mechanical compressive strength after 2 hours 15-27 MPa of dry samples 28-48 MPa. 1 tab.

Description

The invention relates to the building materials industry and can be used in the production of gypsum binders, obtained by heat treatment of lump of gypsum stone, followed by grinding.

Various methods are known for making gypsum binders, for example, producing gypsum binders / -modifications, including grinding gypsum stones in a shaft mill and firing the crushed product in digesters. According to this technology, they are released into life at most gypsum plants in the country.

The disadvantage of this method is the intermittent mode of operation and the low strength of the binder, due to the firing of the powdery material.

A known method of preparing gypsum in cement - including crushing gypsum stone, heat treatment and grinding the resulting product

When heat treating crushed gypsum stones in drying drums at atmospheric pressure with gas combustion products, followed by grinding the calcined hemihydrate in a ball mill, higher quality gypsum cement / 3 - modifications are obtained compared to the heat treatment of crushed gypsum stones in digesters.

This is due to the fact that when a part of crystallization water is removed from a piece, in the latter, a large number of large crystals are formed with the correct faceting during recrystallization.

Therefore, binder obtained in this way, in comparison with binder made by roasting the crushed powder in digesters, is characterized by lower water demand and greater strength.

However, especially when using low quality raw materials with

(L

WITH

x |

00

J

CN About Yu

low content of calcium bicarbonate and in this case it is obtained in the binder with low strength of the order of grades G-2, G-3.

At the same time, for the manufacture of a number of products (for example, the most widespread gypsum plasterboards), gypsum binder of at least grade G-4 (dry strength 8 MPa) is required.

The closest in technical essence and the achieved effect to the claimed is a method of producing a crushing gypsum stone in autoclaves by heat treatment under pressure with saturated steam, followed by drying and grinding the calcined hemihydrate.

With this method, a gypsum cementing "-modification of the G-10 brand is provided.

The disadvantage of this method is the low strength of the resulting gypsum binder.

The purpose of the invention is to increase the strength of gypsum binder.

This goal is achieved in that with the known method for producing gypsum binder, including heat treatment of lump gypsum stone and grinding it, grinding is carried out in the presence of dry superplasticizer, and the duration of transportation of the gypsum raw material that has undergone heat treatment and its exposure time in the feed hopper for grinding should be organized so that the material before grinding is not self-cooled to a temperature of less than 75 - 80 ° C. The amount of superplasticizer added is 0.2-0.8%.

The invention is as follows

The burnt lumpy gypsum stone with a temperature of at least 75-80 ° C and dry superplasticizer are loaded into a ball mill and they are ground together until the finished product is obtained.

The compositions and test results of samples made by the proposed and known methods are presented in the table. As can be seen from the table, the use of the proposed method allows to increase the strength of gypsum binder by 40 - 96% and reduce water demand by 6-50%.

In this case, when using gypsum

drying “-modification for the manufacture of building materials, drying is not required, since the water-gypsum ratio of the mixture will be only 0.2-0.3, which corresponds to the humidity of the finished product

1.5-11.4%.

Using this method allows to increase the strength of gypsum binder by 40 - 90% and, accordingly, in the manufacture of "-modification to obtain brand material not lower than G-4, and in the manufacture of" -modification, respectively, in brand cement not lower than G-19.

In addition, the aodine demand of "-modification is significantly reduced (up to 20-30%),

which in the manufacture of products based on them allows us to exclude a whole technological redistribution-drying.

The economic effect is due to an increase in the brand and the possibility of manufacturing on its basis a wider range of products, with the exception of the drying process (in some cases) and, accordingly, the uselessness of drying plants, and an increase in the productivity of production lines.

Claims (1)

The claims A method of producing gypsum binder, including heat treatment of gypsum stone and its grinding, characterized in that, in order to increase the strength of gypsum binder, grinding is carried out in the presence of superplasticizer C-3 based on the sodium salt of the condensation product of naphthalene sulfonic acid with formaldehyde at a temperature not less than 75-80 ° С, The content of components, wt.% Gypsum plaster 99.9 99.8 99.5 99.2 98 bb modifications 99.9 99.8 99.5 99.2 98 Gypsum plaster - - modifications Superplastic, S-gZ 0.1 0.2 0.5 0.8 2 0.1 0.2 0.5 0.8 2 Index Gypsum plaster ratio 0.37 0.3 0.23 0.2 0.18 0.4g 0.4 0.45 0.43 0.4 O, Temperature hy- „„, Owl stone 70 100 103 35 South Ossetia 93 90 95 88 60 100 The mobility of the test on the diffusion of the cylinder Suttard, „„ mm 175 180 180 185 185 175 175 175 180 185 185 180 Heat treatment of material No drying required Compressive strength after 2 hours, MPa15 19 22 25 .2 3.3 M, 95 5.5 6.0 13 Hedgehog Strength dry samples, MPa 28 35 40 A 48 6.1 8 l 9.4 Yu, 8 11.7 25 100 99.9 99.8 99.5 99.2 98 100 0.45 0.43 0.4 O, „„, 95 88 60 100 „„ 180 185 185 180 and Drying 95 5.5 6.0 13 l 9.4 S, 8 11.7 25 0.5 96 180 2.9 5.5