Lindberg/MPH shipped a gas-fired aluminum stack melting and holding furnace to a company in the secondary smelting industry. The furnace, which has a melt rate of 4,500 pounds per hour, will be utilized to produce aluminum ingot and sows. It is designed with access grating and a ladder for safe access to roof-mounted equipment during maintenance. A three-point laser metal-level sensor is provided that notifies operators of the current furnace metal level through an attached light tree.

In this application, the stack will be fed continuously, which maximizes efficiency in keeping the stack full, especially with a low-density charge that aluminum scrap can present. As it melts, the metal flows into the holding chamber, where it is alloyed to a certain specification. In addition to low fuel consumption, this technology lends itself to lower metal loss due the burning off of contaminants in the stack.  Equipment motion, temperature control, combustion control, stack level control and metal-level control are handled by a PLC and HMI in the control panel.

According to Lindberg/MPH, the stack melter design is the most efficient method of melting scrap and ingot as it utilizes combustion gases to preheat the material in the furnace stack prior to melting. The stack melter top portion allows the necessary flue gases to be exhausted while insulating the other portions for fuel efficiency.