Operation with acidic or basic slag

A flux is used to render the slag fluid enough to separate from the iron and to allow it to flow freely from the cupola. The most commonly used flux is limestone (calcium carbonate), which calcines in the cupola shaft to form lime, a basic oxide, which then combines with the other slag-forming constituents (mainly acidic in character) to provide a fluid slag. 

The basicity of a slag is given by the following ratio (CaO % + MgO %)/Si02 % 

Most cupolas operate with an acidic or slightly basic slag (basicity 1.2). Basic cupolas (basicity up to 2) offer 3 advantages higher carbon lower sulphur 

But they present the following disadvantages silicon losses are high 

For acidic cupolas, dry filters can be used. The slag of basic cupolas has a higher melting point. So a flux based on Cap2 is generally used to maJce it fluid. In this type of cupola, there are emissions of fluor-containing components. This necessitates the application of wet scmbbers for efficient capture of these components. 

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