Gypsum

Brief Overview

Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate.

Manufacturing Process

Gypsum is processed in five stages:

1. Excavation is carried out by digging out an area of ground where the gypsum is located using open-cast techniques. To reach deeper deposits drift or shaft mines may be needed. 
2. Crushing the gypsum rock, especially if subsequent heating is to be done in a pan rather than a shaft kiln. Crushing should reduce the gypsum to grains of less than a few millimetres across. 
3. Screening with a sieve will remove large grains which have not been crushed properly which may contain impurities.
4. Grinding if the gypsum is to be used for high quality plasterwork or for moulding, medical, or industrial applications. The relatively soft gypsum could be pulverised in agricultural mills.
5. Heating by using a rotary dryer to dewater the materials, and a cyclone collector to gather the final gypsum powder for final application.
    

Construction Industry

• Gypsum in board form is used as a finish for walls and ceilings
• Concrete blocks and mortar
• Binder in fast-dry tennis court clay

Agricultural Industry

• Fertilizer and soil conditioner
• Agent for reclamation of saline soils

Other Applications

• Plaster ingredient in surgical splints, casting moulds and modeling
• Wood substitute
• Tofu coagulant