Although not a new technology, the ladle refining furnace (LRF) method has of late become popular among steel manufacturers for the production of construction grade steel.
This spurt in its adoption is attributable to the Government of India’s focus on large-scale infrastructure projects, including ports, bridges and dams, as well as high rise buildings in urban areas. All these projects require the usage of 500D grade TMT bars. And LRF is the ideal method of producing high quality construction grade steel for producing “D” grade TMT bars as per the IS:1786 norms.
So, what is the Ladle Refining Furnace process and what are its benefits?
Ladle Refining Furnaces (LRF) are used to desulfurize steel, remove other impurities and hold the molten steel for casting operations. Large ladles are used in most metal-melting operations to transfer molten metal from melting furnaces to refining or pouring stations
The LRF Process
The Ladle Refining Furnace process can be applied once the basic steel has been produced in an oxygen furnace, arc furnace or induction furnace. In the LRF method, the steel is then transferred to the ladle for further refining, such as chemistry adjustment or inclusion modification. These treatments are carried out in the ladle, which is provided with a heat source to heat the liquid metal and compensate for thermal losses.
In other words, LRF is the furnace in which the quality of steel is improved by refining and heating. In the field of process metallurgy, refining steel in the ladle is known as secondary metallurgy.
Benefits of the LRF method
There are a number of benefits that accrue from using the LRF process to refine steel. These include
- Homogenizing the composition and temperature of the molten steel
- Making the steel cleaner, by the removal of oxygen inclusions
- Improving grain refinement in the microstructure
- Degassing of the steel, through inert gas purging
- Saving on Ferro Alloys consumption
- Increasing productivity, as the melting furnace gets emptied earlier
At present, the Ladle Refining Furnace process is the most effective method for producing high quality construction grade steel. Considering the growing number of large-scale infrastructure projects being commissioned and executed throughout the country every year, the LRF process will remain a popular process in the foreseeable future.