Value Addition & Reducing Energy Wastage in Re-Rolling Mills

This technology is a process to utilise the energy that is presently being wasted - equivalent to around Rs. 250 per tonne at current price of furnace oil. The resulting product, high quality rebars as per international standards has the potential to save the country about Rs. 500 crores every year on the basis of an annual demand of 3.5 million tonnes. The additional gain is a better chance of survival in calamities such as earthquake. The adoption of this technology results in following benefits:

Utilising the available heat energy of rolled rebars (900 to 9500C at the cooling bed) to give a value added product of world standard instead of entirely wasting this energy as done in most rerolling mills. This productive utilisation of energy is equivalent to Rs. 250/ T, being the cost component corresponding to 9000C, of furnace fuel used in the reheating furnace.

Yield improvement of approximately 0.7% due to reduced scale loss-gain of Rs. 100/ tonne. Saving of about Rs. 80 to 100/ tonne in twisting and material handling costs. A saving of 8-15% in steel used in RCC works - benefit of Rs. 1500/ tonne to the customer besides the benefit of using rebars with high elongation values of 18 to 22% providing greater safety in buildings and civil construction - a potential saving of Rs. 500 crores each year at the national level.

By and large, most re-rolling mills in the country produce cold twisted deformed (CTD) bars used as steel reinforcement in civil construction. In the sixties, the basic raw material for the mills was 50 or 60 mm Mild Steel (MS) billets which gradually got replaced by 75 mm and later 100 mm billets because the main steel plants stopped the production of smaller size billets due to economic compulsions. This change in size of raw material was the first major challenge faced by re-rollers. While a few mills addressed this problem by upgrading their mill to allow for efficient rolling of 100 mm billets and the increased billet weight, most mills failed to do so or only undertook incomplete measures due to financial and technical constraints. They did not provide proper size of roughing stand, did not allow for problems longer loop lengths caused by increased billet weights, did not modify the reheating furnace etc. In short, the mills entered a phase of good returns in spite of inefficient operations as the protected market conditions prevailing in the country allowed them to make profits.

The second major crisis faced by the re-rollers was the global hike in oil process in early seventies. Here again the protected market conditions and lack of competition 'came to the rescue'. They merely made adjustments in prices of their products to compensate the increased fuel oil costs and continued to make profits.

Quality, efficiency, good yields, low wastage, reduction of operating cost and a host of similar yardsticks which generally engage the minds of mill personnel worldwide were totally neglected in the country and no attempts at improvement were made.

Areas of Application: Steel re-rolling sector

Advantages

The development of this technology has been great boon to the civil industry the worldover as an acceptable alternative to the use of rebars made from steel alloyed with costly elements. The Indian region, where CTD rebars has had a stranglehold for the past two decades, is today waking up to the benefits of the rebars primarily on account of:

• Superior product with consistent properties
  
• High strength combined with high ductility
  
• Easy manufacture of different strengths of rebars from mild steel grades
  
• Saving in steel consumption when using this technology in place of CTD rebars
  
• Better fatigue resistance
  
• Better weldability
  
• Easy and less construction time
  
• Lower production costs.
  

Most importantly, the technology is an in-line process and the high strength rebars are ready for despatch to the customer almost immediately after rolling is complete - unlike the few days taken in the case of CTD rebars which results in large inventory levels in the mill.

Stage of Development : Commercialised

Inputs Required: As per common parameters of a running unit.

Economic Data: Preliminary feasibility report available can be provided on request.


Transfer Forms: Transfer of technology and other technical assistance

Main Application: Energy

Source: Technology Bureau for Small Enterprises
APCTT Building, Qutub Institutional Area
P.O. Box – 4575
New Delhi – 110016, India