Brief calculation of calcined gypsum

Brief Calculation of Calcined Gypsum
Natural gypsum: When the free water content is 2%, the purity is 85%, the temperature for removing free water is 120 ℃, the calcination temperature is 150 ℃, and the theoretical chemical reaction heat is 104.5 kJ/kg (25 kcal/kg). It is calculated that when 1 ton of dihydrate gypsum is heated to remove 3/2 crystalline water and form hemihydrate gypsum, the required heat is 58.52 × 104 kJ/t (14 × 10 4kcal/t). This calculation result is consistent with foreign data, such as the data from Germany's Knauf company. For a purity of 90% and a free water content of 15%, the theoretical required heat is 58.52 × 104-59.77 × 104 kJ/t (14 × 104-14.3 × 10 kcal/t). The theoretical calculated value in Japanese and British data is 58.52 × 104-71.06 × 10 4 kJ/t (14 × 104~17 × Between 104 kcal/t).
Desulfurized gypsum: The free water content is between 10% and 15%, and when calculating the gypsum production line, 12% is taken. Therefore, the evaporation heat of this free water is much greater than that of natural gypsum. Based on these conditions, for a purity of 95% and a free water content of 12%, the theoretical heat required for 1 ton of desulfurization gypsum is 79.42 × 104kJ/t (19.0 × About 104 kcal/t).
Phosphogypsum: Phosphogypsum contains higher free water content. If calculated at an average of 18% and purity of 90%, the theoretical heat required for gypsum powder equipment is 91.96% × 104kJ/t (22.0 × About 101kcal/t).
The above is only a purely theoretical calculation, and for different heating and calcination methods, equipment selection, calcination process systems, etc., the theoretical heat demand can be calculated for a specific calcination equipment. However, the actual production conditions are more complex, resulting in a significant difference between the actual heat consumption and the theoretical heat consumption. For example, the theoretical heat demand for the frying pan and rotary kiln provided by German company Knauf is:
58.4 × 104-59.86 × 104 kJ/t (14.0 × 101-14.3 × 101 kcal/t). The actual heat consumption of the fryer during production is 117.2 × 10 4-125.6 × 101 kJ/t (28.0 X 101~30.0 X 104 kcal/t). The difference in numbers is more than twice. The actual heat consumption of domestic calcination equipment will be introduced in each calcination equipment.

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