Лаборатория иши №5

Materials, equipment and reagents required for the experiment.

1. 
   Drying cabinet.
   
2. 
   Porcelain mortar.
   
3. 
   №008 elak.
   
4. 
   Boiler or pan.
   
5. 
   Sandy laboratory bathroom.
   
6. 
   Electric hob or gas burner.
   
7. 
   Metal sleeve thermometer.
   

Procedure.

In the laboratory, the product of phosphogypsum binder, which is a waste of mineral fertilizers - for the production of gypsum, slightly dried phosphogypsum in a pre-drying oven is ground in a laboratory mill or porcelain kiln to a level that meets the requirements of GOST 125-70. Then № 008 is passed through a sieve until a residue of 15% remains. It is then placed in a drying oven at a temperature of 50-950C and dried for 2-3 hours, stirring constantly. Drying is continued until the weight becomes constant. As a result of drying, phosphogypsum is dried from hygroscopic moisture and we determine the amount of bound water. Theoretically, the bound water is 20.93%, which in turn corresponds to two molecules of water. In practice, due to the presence of various compounds, the amount of bound water is relatively small.
Thoroughly ground and dried phosphogypsum is placed in a pot (pan) heated using a gas or electric stove, placed in a sandy laboratory bath and slowly heated.
During cooking, the temperature of the phosphogypsum powder is measured using a thermometer. The thermometer is mounted on a metal sleeve, with which the phosphogypsum is frequently stirred.
Thus, the thermometer in the sleeve acts as both a stirrer and a temperature gauge.
Care should be taken to ensure that the temperature does not exceed 150-1600C during cooking. To do this, the burner flame is changed or the electric hob is switched on and off from time to time (the temperature can also be controlled by using an autotransformer to supply the appropriate voltage to the electric hob). Cooking takes 2 hours. SThe water bound to the right (hydrate) is determined. Theoretically, the bound water should be 6.21%.
The results obtained are recorded in the table.

Duration of cooking time	30 min	60 min	90 min	120 min
Product weight

Books.

1. 
   YU. M. Butt, VV Timashev and others.
   
2. 
   TA Otakuziev, ET Otakuziev «Binders». Toshkent-2002 y.