Simple Solutions That Work! Issue 12

18 than most other types of furnaces resulting in a greater utilization of heat energy. The efficiency of these types of furnaces ranges from 900 to 1100 Btu per pound. These furnaces are also typically far more expensive. Even though they hold less than reverbs typically hold they still take up about as much room because of their loading mechanism attached to the stack to carry the scrap and ingot up to the top of the stack and dump it. It is highly recommended that you load the hearth from the bottom with ingots before first using the dump hopper to plummet the load of ingots and scrap down on the refractory hearth. Most of these units as well have high melt losses when melting lightweight scrap. Typical die cast and foundry loses are between 5-7% depending upon the density of the scrap. FUEL FIRED HIGH HEADROOM REVERBS The next most common type of furnace is called a reverb taking its name from years past where a separate chamber that was coal fired reflected its heat off of a sloped wall and the furnace roof to heat the molten bath of metal. Most reverb furnaces are closed box type furnaces with a bath depth of around 22-30 inches. Many have high side walls and the dimension from the molten bath to the to the underside of the roof is 4 feet or greater. These higher walled furnaces have tall door openings and usually wall fired burners. These burners usually are convective and depending on the type can cause agitation of the metal as they are trying to push the heat into the metal. The efficiency of these types of furnaces ranges from 1700 to 1900 Btu per pound. Many in the extrusion industry use this type of furnace as they have rejected extrusion sections, they need to charge that are bulky. This is commonly known as a batch melter. Most secondaries use these furnaces because of their capability to melt a lot of metal sizes range from 80,000# capacity to 350,000# and more. It is advisable to circulate the metal in these large furnaces to keep the metal more homogenous and the alloying agents in solution. Sometimes these are referred to as… Well Melting Furnaces taking its name from an external well that either scrap or return parts or gates and risers are charged into. These types of furnaces or versions similar are found in the die casting, foundry and secondary industry. The external well is an ideal place to charge dirty scrap and thin sections as there is a greatly reduced metal loss when these items are melted by submersion into a molten bath versus being exposed directly to the products of combustion or direct flame impingement. The other benefit is that the coatings and volatiles are burned of in the external well that is hooded and ducted to a baghouse. Further as most well melters have submerged openings to allow circulation of the hot metal to the well the drosses, oxide and residue from the dirty scrap remain in the well and do not enter the main chamber. The dross and residue are easily skimmed from the well metal surface. The main chamber therefore remains a little cleaner and acts more as the heat sink Most of these units are side wall fired and have high side walls and tall door openings to accommodate cleaning their large interior areas. The heat absorbed by the main chamber is typically transferred to the well through the submerged eyelets in the hot wall separating Tower or Stack Melter High Headroom Melter