Technological processes in the production of calcium sulphate binders

Of the many methods of production over time to identify some of them, that on investment and production costs, and processability of various raw materials are most suitable. Compared with North America or Japan, optimizing production methods in Europe should focus not on one product - gypsum board, and on a few basic products that are developed and implemented almost simultaneously, and are used interchangeably. These basic products in Central Europe are:

· Gypsum plaster for machine

· Plasterboard

· For spreading gypsum plaster.

So as gypsum, raw materials for these products have different requirements, and apply various production units for maintenance of calcium sulfate. They are:

· Rotary kiln

· Grate (cloth)

· Digester

· Autoclave.

These plants can be processed like natural gypsum and gypsum-UUSDG. Natural gypsum is mined in quarries and open pit mines occasionally closed method. The rock is crushed and milled to a size of grains, which is necessary for the corresponding firing process and, where appropriate, homogenized in the mixing silo.

UUSDG-gypsum is obtained as a wet fine product with a water content up to 10%. In a rotary kiln or autoclave it can be used without pretreatment, and the grate for gypsum-UUSDG web must first be dried and homogenized. In the future, they will be briefly explained the most important modes of production.

Autoclave method for producing α-hemihydrate

When the autoclave method used ground gypsum (0-200 microns) or UUSDG-plaster in its original condition. Dehydration occurs at about 130 0C and a pressure of 2 to 2.5 atmospheres. autoclave Units built for the passage of 150 tons / day. Figure 1.63pokazyvaet flow chart of a continuous autoclave process for the production of α-hemihydrate. This process produces commercially pure α-hemihydrate. alpha-gypsum (due to the method of producing is also called "autoclave gypsum") because of its large number of inclusions (low water requirement) and its high mechanical strength is particularly well suited for use in mass for spreading plaster and putty. With it, easily achieved the 28-day strength of 50-60 newtons / mm2. Along with the continuous production method is also used periodic (intermittent) method.

99. Autoclave method for producing α-hemihydrate

When the autoclave method used ground gypsum (0-200 microns) or UUSDG-plaster in its original condition. Dehydration occurs at about 130 0C and a pressure of 2 to 2.5 atmospheres. autoclave Units built for the passage of 150 tons / day. Figure 1.63pokazyvaet flow chart of a continuous autoclave process for the production of α-hemihydrate. This process produces commercially pure α-hemihydrate. alpha-gypsum (due to the method of producing is also called "autoclave gypsum") because of its large number of inclusions (low water requirement) and its high mechanical strength is particularly well suited for use in mass for spreading plaster and putty. With it, easily achieved the 28-day strength of 50-60 newtons / mm2. aryadu continuous production method is also used and periodic (intermittent) method.

Figure 1.63-technological scheme continuous autoclave process for the production of alpha-hemihydrate [187]

1 - raw plaster, 2 - dosing belt weigher, 3 rotary kiln with a kiln chamber, 4 pre-mill, 5 - air separator, 6 - fine grinding mill, 7 - electrostatic precipitator (dust removal)

 

Figure 1.64-production finishing (plaster), gypsum calcination in a rotary kiln

100. Gypsum boiling kettle for the production of ß-hemihydrate

In gipsovarochny boiler (kettle) loaded UUSDG-dried plaster or gypsum, which is crushed in a grind-drying plant to 0-2 mm and dried at the same time. Gipsovarochnye boilers heated directly and not designed for continuous operation. After exiting the boiler gypsum reaches approximately 150 0C in temperature. Figure 1.65pokazan continuously working gipsovarochny boiler. Existing plants have a capacity of about 700 tons / day. This gipsovarochny boiler produces ß-hemihydrate with small amounts of ß-anhydrite III and anhydrite virtually absent II. Most part obtained in this way is used for manufacturing gypsum building boards and gypsum, in particular gypsum boards.

Large boiler gipsovarochny submerged burner for continuous production of ß-hemihydrate (plaster finishing) comprises: mixer, - the boiler casing, 3- lift pipe for exit of the finishing plaster, - combustion chamber, - exhaust gas channel to the furnace, - a dip tube submerged burner - fan for exhaust and accumulating gases.

Level (12 points)