electric arc furnace

Examples of electric arc furnace in the following topics:

• Steelmaking and Refining

  • Secondary steelmaking is most commonly performed in an electric arc furnace.
  • Once the furnace is charged with scrap metal, meltdown commences.
  • The electrodes are lowered onto the scrap, an arc is struck, and the electrodes are set to bore into the layer of shred at the top of the furnace.
  • Once the electrodes have reached the heavy melt at the base of the furnace and the arcs are shielded by the scrap, the voltage is increased and the electrodes raised slightly, increasing the power to the melt.
  • For plain-carbon steel furnaces, as soon as slag is detected during tapping, the furnace is rapidly tilted back towards the deslagging side, minimizing slag carryover into the ladle.

• Metallurgy

  • Physical properties of valuable materials can include density, particle size and shape, electrical and magnetic properties, and surface properties.
  • Often, however, energy must be added to the process by combustion of fuel or, in the case of some smelting processes, by the direct application of electrical energy.
  • The metal of interest is plated onto the cathode, while the anode is an inert electrical conductor.

• The Mass Spectrometer

  • In order to measure the characteristics of individual molecules, a mass spectrometer converts them to ions so that they can be moved about and manipulated by external electric and magnetic fields.
  • A perpendicular magnetic field deflects the ion beam in an arc whose radius is inversely proportional to the mass of each ion.

• Cathode Rays

  • The image in a classic television set is created by focused beam of electrons deflected by electric or magnetic fields in cathode ray tubes (CRTs).
  • The early cold cathode vacuum tubes, called Crookes tubes, used a high electrical potential between the anode and the cathode to ionize the residual gas in the tube.
  • The electric field accelerated the ions and the ions released electrons when they collided with the cathode.
  • Modern vacuum tubes use thermionic emission, in which the cathode is made of a thin wire filament that is heated by a separate electric current passing through it.
  • In 1838, Michael Faraday passed a current through a rarefied air-filled glass tube and noticed a strange light arc with its beginning at the cathode (negative electrode) and its end almost at the anode (positive electrode).

• The Alkaline Earth Metals

  • Even beryllium fluoride, which is the most ionic beryllium compound, has a low melting point and a low electrical conductivity when melted.
  • Magnesium oxide (MgO) is used as a material to refract furnace brick and wire insulation (melting point of 2852°C).