Gypsum is a soft mineral that has been used in the construction industry for centuries. There are a number of reasons for its popularity: it is relatively lightweight, easy to mold and cut, and does not burn.
One of the oldest and most widely used building materials is gypsum. It is derived from limestone and provides a number of benefits to society. For instance, it is lightweight and easy to cut, which means that it’s easier to transport and work with. Additionally, gypsum is soft enough that it can be carved into intricate shapes like statues.
Gypsum is known with the chemical formula “CaSO4.2H2O”, and it consists of 79% calcium sulfate, and approximately 20.9% of water. Usually, raw gypsum contains many impurities, the most important of which is sand, “silica SiO2“, and calcium carbonate “CaCO3”.
About the history of gypsum
Gypsum has been used in construction since ancient times, especially in ancient buildings in Egypt and Rome, and this indicates that man knew gypsum since nearly six thousand years BC, and one of the most famous evidence of this is the existence of the pyramids until the current era.
It was found in many historical manuscripts dating back to the era of the Romans that they used plaster, and they were ordering the owners of the buildings to cover all the walls with plaster to protect them from fire. The Romans knew since ancient times the unique benefits and advantages of gypsum that prompted them to use it.
Gypsum industry
For the manufacture of gypsum must go through four stages, namely:
Raw material preparation stage
At this stage, gypsum is taken from special quarries and is in the form of large stones. These quarries cannot be burned without resorting to crushing, masonry, and then grinding into a powder. The crushing process is not considered a difficult process. The grinding process is also not a difficult process, but the plaster must be sieved afterwards to be ready for the burning process.
Roasting stage
At this stage, the plaster is roasted in order to obtain gypsum of type SH – B, and there are many methods that are used in roasting, the most important of which are:
*Open trough method.
*Intermittent boiler method.
*The successive and continuous spiral method.
*conveyor belt method.
*Rotary horizontal boiler method.
*Countercurrent continuous rotary kiln method.
The plaster is roasted in order to obtain gypsum of the SH-a type, and there are many methods that are used in roasting at this stage, the most important of which are:
*Locomotive method.
*Aquarius method.
Grinding stage
The resulting gypsum is ground after the second roasting process, and after grinding the gypsum must be sieved, take out the large granules and grind again.
Storage stage
Usually, the gypsum resulting from the grinding process is not used directly, and the reason for this is that it is almost immature, and therefore the ground gypsum is stored in special warehouses for short periods until it matures by absorbing some quantities of water in the atmosphere to become more homogeneous and mature.
Gypsum uses
Gypsum is used in many different areas of life:
1. Gypsum is used in decoration, finishing and construction works.
2. Gypsum is used in the cement industry.
3. Gypsum is used as soil fertilizer.
4. Gypsum is used to adjust the soil temperature.
5. Gypsum is used in the glass-making process.
6. Gypsum is used in the manufacture of chalk used in educational blackboards.
7. Gypsum is used as a splint to fix the broken limbs in the human body until complete recovery and to remove the splint.