Past Challenges

REWARD - RS 1,00,000
Ferous Oxide

Steel/LD slag is a by-product generated during manufacturing of steel. Primarily, this slag consists of calcium, magnesium, manganese and aluminium silicates in various combinations. Although the chemical composition of slag may remain unchanged, physical properties vary widely with the changing process of cooling. Typically, for iron ore feed containing 60 to 65% iron, steel slag generated is approximately 20%, by mass, of the crude steel output. 

A considerable portion of this steel slag in India and around the world (We generate about 2 million tons) is being disposed in open lands. Dumping in open land could lead to air, water and land pollution.  To avoid this, various applications of steel/LD slag have been developed in many Countries. One of the major usage of this slag is as a replacement of natural aggregate in road construction. The major problem of using this slag in road construction is that it expands due to the presence of un-hydrated free lime and small quantities of magnesium oxide.  If such a product is used in construction, it adversely influences both the mechanical and physical properties.

We have evaluated various (and used a few) techniques to solve this problem. These are:

  • Natural aging : It takes more than a year and needs lot of land as the ageing time is approx.1.5 years.   
  • Dry and Wet cycle aging : It takes about 3 -6 months to age the slag but the uniformity is not ensured. It also needs large tracts of land. 
  • Open Steam ageing : In this method the steam is passed through the slag to age it.
  • Pressurised Steam aging : It is quick and needs less area but is very costly to set up and run such a plant.   

We are looking for solutions (not theoretical ideas) that will enable us to age (remove free lime completely) the Steel Slag quickly, economically and without the need of a large piece of land.

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