RU2270813C2 - High-strength gypsum production method - Google Patents

Abstract

FIELD: binding material, particularly high-strength gypsum production.

SUBSTANCE: method involves hydrothermally treating natural dehydrate gypsum rock with saturated steam under 1.3 kg/cm² pressure; drying thereof under atmospheric pressure. Above treatment is performed at 100-130°C temperature for 7 hours. Then the gypsum material is subjected to evaporation under excessive pressure of 0.2-1 kg/cm² along with uniform temperature reduction up to 95-96°C temperature obtaining. Then the material is dried and cooled for 5.5 hours under atmospheric pressure to reduce gypsum temperature up to 45°C. The treated material is crushed and grinded to obtain gypsum particles having 0.2 mm dimensions, wherein not more than 0.2% of gypsum particles remain on sieve having 0.2 mm openings.

EFFECT: increased gypsum quality due to provision of uniform regular gypsum structure by uniform cooling of gypsum subjected to hydrothermal treatment.

1 tbl, 2 cl

Description

The invention relates to the field of manufacture of binders, more specifically high-strength gypsum, and can be used in construction, engineering and other industries. To obtain high-strength gypsum in an autoclave, hydrothermal treatment of gypsum stone with saturated steam under pressure is necessary. Under the influence of temperature and pressure, water is released from the gypsum stone in a liquid state. This is followed by drying, crushing and grinding of gypsum. The method of hydrothermal treatment of gypsum is widespread. A known method of producing a gypsum binder in an autoclave (AC 513578277, C 04 B1 1/02, 1976), according to which the process of producing gypsum is carried out with a dry coolant with a temperature of 110-120 ° C at a pressure of 2-8 kg / cm ² until complete replacement saturated steam, and the final drying is carried out cyclically: evacuation to a residual pressure of 360-260 mm RT. Art., air purge at a temperature of 120-150 ° C for 3-15 minutes. There is also a method for producing high-strength gypsum binder described in the description of (AC 111167861 A1, C 04 B 11/02, 1993), according to which steaming of natural two-water gypsum of a fraction of 40-60 mm is carried out at a pressure of 1.2-1.3 kg / cm ² for 1.5-2 hours, then the pressure is increased to 7-8 kg / cm ² for 0.5-1 hours, after which the pressure is reduced to atmospheric for 0.3-0.5 hours, drying is carried out for 2.5-3 hours. However, there are no known methods for regulating pressure and temperature parameters for a certain period of time when hydrothermal treatment, drying by evaporation in an autoclave, drying in a hotel drying chamber, and cooling are performed, which makes it possible to obtain high-strength gypsum with improved characteristics.

The objective of the invention is to improve the quality of high-strength gypsum by obtaining a uniform defect-free structure obtained by cooling gypsum obtained without hydrothermal treatment uniformly without temperature dips. The problem is solved in that in a method for producing high-strength gypsum, including hydrothermal treatment of natural two-water gypsum stone with saturated steam at a pressure of 1.3 kg / cm ² , drying at atmospheric pressure, according to the invention, said treatment is carried out in a temperature range of 100-1300 ° C for 7 hours, then for 5.5 hours carry out the alignment at an excess pressure of 0.2-1 kg / cm ² with a uniform decrease in temperature to 95-96 ° C, drying and cooling to 45 ° C at atmospheric pressure.

The problem is also solved by the fact that after cooling, crushing and grinding is carried out to a fineness of grinding of 0.2 mm with a maximum residue in a sieve with a cell in the light of 0.2 mm not more than 0.2%

The values of the actual improved performance of a particular brand of gypsum obtained on the basis of the proposed method are given in table 1.

Table 1. No. p / p The name of indicators GOST requirements Actual Results one Setting time for quick-setting gypsum, min Start end setting start no earlier than 2 end no later than 15 3 7 2 Fineness of grinding, residue on a sieve with a 0.2 mm mesh for fine grinding, not more than,% 2 0.2 3 The tensile strength of samples of jars 4 · 4 · 16 cm at the age of 2 hours for brand G-15 under compression kg / cm, MPa 150; (15) 146: 150 (14.6; 15.0) when bending kg / cm, MPa 58.3; (5.83) 59.0; 60.0 (5.9; 6.0)

The whole process is divided into the following technological cycles:

- loading gypsum stone fraction 30 mm into the autoclave and its hydrothermal treatment with saturated steam at a pressure of 1.3 kg / cm ² at a temperature of from 100-130 ° C for 7 hours;

- within 5.5 hours, evaporation, drying, cooling.

Evaporation is carried out in the autoclave after turning off the saturated steam pressure under the action of an excess pressure from 0.2 to 1 kg / cm ² created by evaporation of water from the obtained gypsum and controlled by a valve, evaporation is performed to a cooling temperature of 95 ° C-96 ° C;

Then unload for drying in a drying ventilation chamber;

After drying, unload in a tubular water refrigerator to cool to a temperature of 45 ° C;

After which crushing of gypsum stone and grinding to fineness of grinding follows: maximum residue on a sieve with a cell in the light of 0.2 mm is not more than 0.2%

Claims (2)

1. A method of producing high-strength gypsum, including hydrothermal treatment of natural two-water gypsum stone with saturated steam at a pressure of 1.3 kg / cm ² , drying at atmospheric pressure, characterized in that the said treatment is carried out in a temperature range of 100-130 ° C for 7 hours then for 5.5 hours, evaporation is carried out at an excess pressure of 0.2-1 kg / cm ² with a uniform decrease in temperature to 95-96 ° C, drying and cooling to 45 ° C at atmospheric pressure for 5.5 hours 2. The method according to claim 1, characterized in that after cooling, crushing and grinding is carried out to a fineness of grinding of 0.2 mm with a maximum residue on a sieve with a cell in the light of 0.2 mm not more than 0.2%.