Charging of Cupola Furnace

 Charging of Cupola Furnace

Before the blower is started, the furnace is uniformly pre-heated and the metal and coke charges, lying in alternate layers, are sufficiently heated up. The cover plates are positioned suitably and the blower is started. The molten metal starts trickling down and collecting in the well. The height of coke charge in the cupola in each layer varies generally from 10 to 15 cms. The requirement of flux to the metal charge depends upon the quality of the charged metal and scarp, the composition of the coke and the amount of ash content present in the coke. Generally about 40 kg to 50 kg of limestone, in form of flux, per metric ton of the metal is used. The amount of this flux to be charged should be properly determined. The excess amount of flux affects the acid lining of cupola. Lesser amount of the flux than required will result in the loss of molten metal. First charge received of the molten metal is either allowed to drain out or used for rough castings. For having desired composition of the casting, it is essential to control the proportions of its various constituents at the stage of raw material requirement for melting. It is also necessary due to number of losses and gains of different constituents take place inside the cupola during the process of melting. These losses and gains in composition are identified for compensating purposes. The losses or gains of different constituents during melting as identified are given as under:

1. Iron            –    Loss of about 4%


2. Carbon        –    Gain of about 0.1 to 0.15%.


3. Silicon         –   Loss of about 10%


4. Manganese    –  Loss of about 15 to 20%.


5. Phosphorus   –   Practically no change.


6. Sulphur          –   Gain of about 0.03 to 0.05%.

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