What are the steps that are involved in the manufacturing of glass??
Glass Manufacturing process:
Glass is manufactured in the following four steps:
Raw materials :
The raw materials lime, soda and sand separately cleaned, ground, sieved(called ‗Batch‘) in definite proportion and mixed with water are fused in a continuous type(tank) furnace or batch- type (pot) furnace.
Process Explanation :
The charge in the first stage melts, forming a bubbly, sticky mass, and as the temperature is raised (1100°C–1200°C) it turns to a more watery liquid and the bubbles rise to the surface. The melting process in case of ordinary soda-glass involves the following series of reactions:
Chemical Reactions :
CaCO3+SiO2 CaSiO3 + CO2
Na2CO3 + SiO2 Na2SiO3 + CO2
When all the carbon dioxide has escaped out of the molten mass, decolourisers such asMnO2 or nitre (KNO3) are added to do away with ferrous compounds and carbon.
The colouring salts are added at this stage. Heating is continued till the molten mass is free from bubbles and glass-balls. As the glass cools (800°C), it is ready to be drawn or floated to its desired thickness and size at the other end of the furnace.