Balancing Your Cupola Operations
Understanding how the inputs in cupola melting are interrelated with the outputs of molten iron, slag and furnace temperature is crucial to running an
effective, effi cient melt department. LYLE HEBERLING, IRON CASTING RESEARCH INSTITUTE, COLUMBUS, OHIO
C
upola furnace operation is a transformation process, meaning numerous inputs are transformed into out-
puts, primarily iron, slag and the stack gases. T is cycle is straightforward and somewhat automatic. Feedback loops made through testing and analysis take more eff ort, but they ultimately help you improve operations (Fig. 1).
T e cupola melter is a shaft
furnace in which charge materials are fed into the top and continuously melted and discharged at the bottom as long as air is blown into the shaft. Depending on the size of the cupola and volume of air being blown, it can be 30 minutes to an hour before the material charged into the top comes out the bottom. Measurements help
give a clear picture of the cupola operations so you can better control the output of the furnace. While all inputs have an effect
Fig. 1. This fl ow chart illustrates how cupola operations are a transformation process.
on the operations, many cannot be changed by the operator. These include whether the refractory used is acidic or basic, whether the air is cold or hot blast, the type of charg- ing mechanism, charge materials, iron demand, whether it’s lined or unlined, and weather conditions. However, a number of inputs can be changed by the operator day to day and hour to hour and these include the charge makeup, blast volume, blast temperature and use of oxygen (if so equipped) . Decisions about how to change the inputs can be made with the help of monitoring what happens during the conversion process, such as the backpressure of the air going into the furnace, the water temperature to keep
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