In the metallurgical world, reverberatory furnace holds an important place. The main task of reverberatory furnace is to separate the treated or processed material from coming in contact with the fuel. However the contact with the combustion gas is avoided.

Reverberatory furnace is used for smelting, refining, or melting in which the fuel is not in direct contact with the contents but heats it by a flame blown over it from another chamber. This furnace is applied in copper, tin, and nickel production, in the production of certain concretes and cements, and in aluminum recycling. In steelmaking, this process is called the open-hearth process in which the heat passes over the hearth and then radiates back onto the contents. The arched roof slopes downward toward a bridge of flues that deflects the flame so that it reverberates.

Types
On the basis of function, operation and objective reverberatory furnace is classified into two types.

Fusion or Melting Furnaces
Fusion or Melting Reverberatory Furnace are used for various industrial applications. They are used by both founders and smelters in the fusion of metals; in the concentration of poor metallic compounds by fusion into regulus; in the reduction of lead and tin ores; for refining copper and silver; and for making malleable iron by the puddling processes and welding.

Wasting or Calcining Furnace
Calcining furnaces on the other hand are employed to convert metallic sulphides into oxides by continued exposure to the action of air at a temperature far below that of fusion or into chlorides by roasting with common salt. Here heat is properly regulated during operation otherwise it may lead to the clotting or fretting together of the masses this is generally done by making the bed of the furnace very long in proportion to its breadth and to the fire-grate area, Such calcining furnace are used especially for roasting zinc blend into zinc oxide, and in the conversion of copper sulphides into chlorides in the wet extraction process.

Classifications on the basis of Functions
On the basis of function the reverberatory furnace can be classified as:

Lead Reverberatory Furnace
Reverberatory furnaces are designed and operated to produce a soft, nearly pure lead product. The smelting process involves charging and tapping of lead and slag. The tapping operations involve pouring the molten lead and slag from the furnace into molds or ladles. Some smelters tap metal directly into a holding kettle, which keeps the metal molten for refining. Other smelters cast the furnace metal into blocks and allow the blocks to solidify. Since in both the process there is a possibility of discharge of large amount of lead fumes so proper care and steps should be taken to minimize such operation.

Aluminum Reverberatory Furnace
For these types of furnaces which are refractory-lined vessels normally employ natural gas-fired burners. Here the the transfer of heat takes place from the roof of the Furnace and to some extent from the side wall for melting operation. Inspite of various variant are utilized for operating procedures, all reverberatory furnaces suffer from large energy losses. The average melting furnace operates at 30 percent thermal efficiency. However some advancement in oil fuel burners including improved insulation, refractories, and sensors and control systems has reduced the problem to certain extent.

Features

• Heat environment is low. This results from the completely enclosed furnace and careful selection of lining components.
  
  
• By opening the charge well covers and through the rear manual access door Sidewalls can be easily accessed.
  
  
• Burners flame impingement on surface metal is reduced by high thermal release.
  
  
• The charge well surface is meant for channelizing the combustion products.
  
  
• Shell construction is strong as the Carbon steel plate is used for welding inside out.
  
  
• Similarly the Upward-rotating covers are also strongly welded with steel plate and are lined with high quality refractories.
  
  

Advantages
Reverberatory furnace has following advantages:

• It is easy to operate and and are highly productive.
• Sidewalls can be cleaned easily. Easy cleaning of sidewalls.
• The life of refractory is long.
• The possibility of oxidation and melt loss is minimum.
• In proportion to the holding volume, the melting is fast.
• It can be installed quickly and easily.
• It's construction ensures easy and complete access to the furnace chamber for charging and cleaning

Applications
Reverberatory furnace has following applications:

• Smelting
• Refining
• Melting
• Copper, tin, and nickel production
• Production of certain concretes and cements
• Aluminum recycling
• Steelmaking