Production of Gypsum

Fig.1.Gypsum Production 

Production of Gypsum involves the following steps:

1. Excavating
2. Crushing
3. Grinding
4. Calcination
5. Cooling and Pulverizing
6. Packing

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Fig. Gypsum Manufacture and Recycling Process
The excavation involves collecting the materials from their source mainly through mining. They are also seen deposited in the sea water or lake. Then it is crushed into particles of size approximately 25mm and subjected to grinding. 

The next main stage in gypsum production is heating of the ground material, It is also called as calcination. Here the gypsum particles are heated to 100 to 190 degree Celsius which result in three forth of water loss from the particle. This process is called as the incomplete calcination or low burning process. Which can be represented by the chemical equation:

CaSO4.2H2O = CaSO4.1/2 H2O + 3/2 H2O
CaSO4.1/2 H2O = Plaster of Paris

The temperature is further increased above 190 degree Celsius which forms high burning process or complete calcination :
CaSO4.2H2O = CaSO4 +2H2O

CaSO4 =  Gypsum-Anhydrite

For the manufacture of drywall and plaster material the mined gypsum is used as the raw material. Synthetic gypsum is used in more amount for manufacture. The wet limestone which is a combination of calcium and water, when combined with sulfate forming calcium sulfate or gypsum is called as a chemical gypsum or synthetic gypsum.

Recycling Of Gypsum

The process of recycling of gypsum involves the conversion of gypsum waste material to the lowest form of raw material. This helps in the manufacturing of new gypsum products in construction. This way the material is sustainable and eco-friendly.
A demonstration of the same is shown in the above figure, as a process along with manufacturing.

Need for Recycling of Gypsum

The recycling of gypsum gain many significance as mentioned below:
  • Reduction in the need for the quarrying and production of virgin gypsum raw materials.
  • 1 ton of the ordinary gypsum , when recycled, will save 1,000 pounds of black alkali, 1 ton of lactic acid and 500 kWh of energy. It saves 28 kwh of energy and 4 pounds of aluminum.
  • The disposal of plaster board causes emission of hydrogen fluid gases which are toxic in nature. It strictly recommended to have a recycling than disposal.
  • Recycling og gypsum helps in the preservation of Natural gypsum