Steelmaking in Induction Furnace May24

Steelmaking in Induction Furnace...

Steelmaking in Induction Furnace Coreless induction furnaces have been used in the ferrous industry for over 50 years and are now one of the most popular means of melting and holding ferrous materials. Induction melting had dramatic growth during the 1960s based on line frequency technology, and later with the large-scale introduction of medium frequency power supply during the 1980s. Making of mild steel in the induction furnace was first experimented during early 1980s and it gained popularity when the production of sponge iron utilizing coal based process of rotary kilns became popular. Induction furnace is a type of electric melting furnace which uses electric current to melt metal. The principle of induction melting is that a high voltage electrical source from a primary coil induces a low voltage, high current in the metal (secondary coil). Induction heating is simply a method of transfer of the heat energy. Two laws which govern induction heating are (i) electromagnetic induction, and (ii) the joule effect. Coreless induction furnace comprises a relatively thin refractory crucible encircled by a water cooled copper coil excited from a single AC supply. When the coil is energized, the fluctuating axial magnetic field causes a current to flow in electrically conducting pieces of charge material within the crucible. The power induced in the charge depends on the physical properties of the material, the flux linking it and its geometric shape. Dependent on the resistivity of the material being melted, the coreless induction furnace converts electrical energy to heat the charge at an efficiency of between 50 % and 85 %, although furnace efficiency is further reduced by thermal losses from radiation from the melt surface and conduction through the furnace lining. Medium frequency induction furnaces which are commonly used for steelmaking use...

Developments of Steelmaking Processes Feb22

Developments of Steelmaking Processes...

Developments of Steelmaking Processes The earliest known production of steel are pieces of ironware excavated from an archaeological site in Anatolia and are nearly 4,000 years old, dating from 1800 BCE (before common era). Horace identified steel weapons like the falcata in the Iberian Peninsula, while Noric steel was used by the Roman army. The reputation of ‘Seric iron’ of South India (wootz steel) amongst the Greeks, Romans, Egyptians, East Africans, Chinese and the Middle East grew considerably. South Indian and Mediterranean sources including Alexander the Great (3rd century BCE) recount the presentation and export to the Greeks of such steel. Metal production sites in Sri Lanka employed wind furnaces driven by the monsoon winds, capable of producing high-carbon (C) steel. Large-scale wootz steel production in Tamilakam using crucibles and C sources such as the plant Avaram occurred by the sixth century BCE, the pioneering precursor to modern steel production and metallurgy. Steel was produced in large quantities in Sparta around 650 BCE. The Chinese of the Warring states period (403 BCE to 221 BCE) had quenched hardened steel, while Chinese of the Han dynasty (202 BCE to 220 CE) created steel by melting together wrought iron with cast iron, gaining an ultimate product of a carbon-intermediate steel by the 1st century CE (common era). The Haya people of East Africa invented a type of furnace they used to make C steel at 1,800 deg C nearly 2,000 years ago. East African steel has been suggested by Richard Hooker to date back to 1400 BCE. Evidence of the earliest production of high C steel in the Indian subcontinent is found in Kodumanal in Tamilnadu, Golkonda in Telengana, and Karnataka and in Samanalawewa areas of Sri Lanka. This steel known as wootz steel, produced by about sixth century BCE was exported globally. The steel technology existed prior to 326 BCE in the region as they are mentioned in...

Induction Furnace and Important Operational Aspects Feb14

Induction Furnace and Important Operational Aspects...

Induction Furnace and Important Operational Aspects   The development of the induction furnace for steel making has been a boon to the small steel producers. These furnaces are easy to install, operate and maintain. These furnaces are smaller in heat size with a low cost investment and preferred by lower capacity steel plants. In these furnaces, steel is produced by melting the charge material using the heat produced by electromagnetic field. The induction furnace consists basically of a crucible, inductor coil, and shell, cooling system and tilting mechanism. The crucible is formed from refractory material, which the furnace coils is lined with. This crucible holds the charge material and subsequently the melt. The choice of refractory material depends on the type of the charge and basically consist of either acidic, basic or neutral refractories. The inductor coil is a tubular copper coil with specific number of turns. An alternating current (AC) passes through it and magnetic flux is generated within the conductor. The magnetic flux generated induces eddy currents that enable the heating and subsequently the melting process in the crucible. The shell is the outer part of the furnace. This houses the crucible and the inductor coils, and has higher thermal capacity. It is made of rectangular parallelepiped with low carbon steel plate and joined at the corners by edge carriers from angular pieces and strips of non-magnetic metal. The cooling system is normally a through one way flow system with the tubular copper coils connected to water source through flexible rubber hoses. The cooling process is important because the circuit of the furnace appears resistive, and the real power is not only consumed in the charged material but also in the resistance of the coil. This coil loss as well as the loss...