Raw Material Processing
The main raw material used is Sponge Iron or DRI. In addition to this, castings and some selected industrial end cuts such as punching, etc are used in predetermined proportions. These different raw materials are graded and stored in very large thesis statement on love consequences of global warming short note raw material yard. The selected raw material sample is then added into the lab furnace for melting. The sample is tested to analyze the chemical composition with the help of in-house spectrometer and C & S apparatus.
The core-less induction furnace used for melting is composed of a refractory container capable of holding the molten bath which is surrounded by water cooled helical coil connected to a source of alternating current. The furnace lining is made of up Silica to withstand the slag condition of mild steel or any plain carbon steel that is acidic in nature. After melting, the furnace is tilted to remove the slag and other impurities that come to the surface of molten metal.
Addition of Micro Alloying Elements
Micro alloying elements are added for refining the molten metal to achieve the desired level of composition. The molten metal is fully killed with Aluminium, Ferro Silicon, and Ferro Manganese. If necessary, de-sulfurising and de-phosphorising is also done to remove all the gases present in the molten metal. Throughout the melting process and micro alloying elements addition process, samples are chemically analyzed to ensure accurate and desired chemical composition.
Ladle Purging Process
Purging is done to the molten metal tapped to the ladle to achieve homogenous chemistry and temperature throughout the ladle. In order to avoid thermal stratification that leads to undesirable varying steel compositions, gas purging is done. Purging is conducted by generating bath turbulence and also helps in removing excessive non-metallic inclusions.
Continuous Casting Process
After purging, the ladle is taken to continuous casting set up where it is placed on the tundish. The material then passes from ladle to tundish and tundish to moduls. Liquid steel is continuously poured into the mould to replenish the withdrawn steel at an equal rate. The withdrawal rate depends on the cross section, grade and quality of steel being produced and may vary between 12-300 inches per minute. Casting time is typically 0.9 -1.2 hours per heat to avoid excessive ladle heat losses.