Foamy slag practice

The foamy slag practice, currently in use in the steel production industry, consists in simultaneously injecting oxygen and carbon (in the form of coal dust) into the slag at the end of the melting. TTie foam of slag is produced by the action of CO bubbles. The CO gas comes from the oxidation of carbon in the metal by the injected oxygen and also from the reduction of the iron oxides (FeO) by the injected carbon. 

Creating a foamy slag improves the heat transfer to the charged units and protects the refractory material inside the furnace. Because of the better arc stability and less radiation effects, slag foaming leads to a reduction in energy consumption, electrode consumption, noise levels and increased productivity. 

Reduction of energy consumption and electrode consumption, lower noise levels and reduction of flue-gas volume. 

Heating time 1584 - 1630 °C min 1 Imin 45sec 7min 30sec 

Slag density is reduced from 2.3 tonne/m to 1.15 - 1.5 tonne/m  

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For smaller furnaces, a single slag door burner is convenient and adequate since the operator can effectively reach all cold spots by aiming the burner as necessary. For larger furnaces, generally three sidewall-mounted burners are optimal (Table 5.1). If a foamy slag practice is employed, roof-mounted burners can reduce maintenance requirements. However, in many cases, roof mounting has led to considerable installation and maintenance costs. 

When utilizing a foamy slag practice, it is also important to control closely slag basicity with simultaneous injection/addition of lime. In addition, the generation of higher CO concentrations and an associated increase in off-gas volume and heat content must be adequately addressed, preferably by some form of post combustion. 

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