A cupola furnace is a tall, cylindrical furnace used mainly to melt cast iron, scrap iron and other metals so they can be poured into moulds to make castings. It is one of the oldest and most widely used furnaces in foundries because it is simple, cheap and can melt metal continuously. The cupola is charged from the top with alternate layers of metal, coke (fuel) and flux (limestone), while a blast of air is blown in from the bottom to burn the coke and melt the metal.
A cupola furnace is mainly used to melt cast iron and scrap iron for castings.
It is a tall cylindrical steel shell lined with refractory bricks.
The charge is fed in alternate layers of coke (fuel), metal, and flux (limestone).
Air (blast) is blown in through tuyeres near the bottom to burn the coke.
Limestone flux removes impurities as slag, which floats on the molten metal.
Main zones: well, combustion, reducing, melting, preheating and stack.
It is simple, cheap and allows continuous melting, but composition control is poor.
A cupola furnace is a vertical, cylindrical steel shell lined inside with refractory (heat-resistant) bricks. Its main parts are:
Working: The furnace is first heated and then charged from the top with alternate layers of: • Coke (fuel) • Metal (cast iron, pig iron and scrap) • Flux (limestone, which removes impurities as slag)
A blast of air is blown in through the tuyeres. The coke burns and produces intense heat, which melts the metal. The molten metal trickles down and collects at the bottom, from where it is tapped out. The limestone combines with impurities to form slag, which floats on the molten metal and is removed through the slag hole.
Main zones (from bottom to top):
Uses: • Melting cast iron and scrap to produce iron castings • Used in foundries to make machine parts, pipes, manhole covers and engine blocks
Advantages:
Limitations:
A cupola furnace is used mainly to melt cast iron, pig iron and scrap metal in foundries. The molten metal is poured into moulds to make iron castings such as machine parts, pipes, manhole covers and engine blocks.
The furnace is charged from the top with alternate layers of coke (fuel), metal and limestone (flux). A blast of air is blown in through tuyeres near the bottom, burning the coke and producing intense heat that melts the metal. The molten metal collects at the bottom and is tapped out, while the limestone combines with impurities to form slag that is removed separately.
The charge consists of three things fed in alternate layers: coke, which acts as the fuel; metal, which is the cast iron, pig iron and scrap to be melted; and flux (usually limestone), which combines with impurities to form slag and keep the metal clean.
From bottom to top, the main zones are: the well (collects molten metal), the combustion or oxidising zone (where coke burns and the temperature is highest), the reducing zone (protects the metal from oxidation), the melting zone (where the metal melts), the preheating zone (heats the charge), and the stack zone (carries away hot gases).
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