In the ambitious search to find an alternative, to the conventional cupola furnaces or midsize induction furnaces, which could save space and maintenance costs, the evolution of Rotary Furnace emerged.  Much sought after by foundry industry, the construction of rotary furnace is different in providing different burners for different fuels.  The personnel and the space requirement are minimal.  Mainly used for the production of gray and malleable cast iron with great accuracy in composition.  The investment cost also is much less that really attracts many foundry people.

Rotary Kiln Furnace and Rotary Hearth Furnace are the two main types of Rotary furnace.  Rotary hearth furnace is designed mostly in heat treatment processes, bloom heating in seamless pipe mills, calcinations, carbon based Direct Reduced Iron production and reclamation of metals.  They come in various sizes.  They are suitable for continuous hardening of gears requiring press quenching or preheating of copper, brass and bronze slugs and billers prior to forging or impact extrusion. To provide heat to the furnace either gas or electricity is used.

Both types are energy efficient.  They do the melting in a very short time and melting losses are very less.  Low quantity of flue gases are let out and the refractory material lifetime is more.  In rotary hearth furnace the temperature inside the furnace is uniform and both charging and discharging are done from the same floor in both types.  Sensitive to distortion parts could be transacted individually.  Parts that vary in shapes and sizes can be given proper treatment.  When thin walled parts are handled charge carriers serve as energy storage.  Hardening depth in gas carburizing and carbo-nitriding process drive is simple and safe in operation.

Hardening, Preheating, Normalizing, heat-treating of wire coils and of large pipes and carbon baking are some of the major areas of application of the rotary kiln type.  In rotary hearth type the list of application is bigger: Bloom/billets reheating for seamless pipe mills, reheating for forging applications, wire coils and large pipes heat treatment, carbon baking, glass parts thermal treatment, calcinations of coal & carbon products, DRI production from ore as well as waste material, iron nugget production, hardening, preheating and normalizing.

Some Rotary hearth furnaces operate at variable speed.   Top portion of the furnace is for charging and for removal of elements.  Oil seals are water-cooled at the hearth.  The fabrication is from continuously welded and reinforced steel shell. Door operation is by pneumatic mechanism.  These furnaces have good space efficiency and versatile capabilities for continuous operation.  For low temperature furnaces, alloy re-circulating fan is provided.  The outer wall of the furnace has long-term stability with minimal resistance around.  This is achieved by low watt density rod with round cross-section over bend elements. There are excess temperature control instruments.

Preparation of various pretreatment facilities becomes unnecessary in rotary kiln furnace.  Used in the treatment of various solid, liquid and gaseous wastes.  This has a long retention time easing the control of the load fluctuations for suitable operation.  Rotary kiln furnaces can perform multiple jobs.  Having a power rating of 500 KW, rotary kiln finds application in gasification and pyrolysis of sewerage sludge. Meant for continuous process, kilns are used even in cement manufacturing and drying of granular materials.  Thus, the versatility of this rotary kiln furnace finds application in many major industrial processes.