Dust formation in electric arc furnace: birth of the particles



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CONCLUSION
From the study of the morphological and mineralogical characteristics of EAF dust samples combined to the knowledge of the EAF steelmaking process, we could determine the mechanisms of EAF dust formation. Among the different sources of emission, the major one is the projection of liquid droplets by bubble burst at the liquid bath surface. We therefore designed an experimental device to observe the gas bubble burst at the surface of liquid steel by means of high-speed video, and to quantify the resulting projections by granulometric and gravimetric analyses. The phenomena involved are similar to those taking place in the case of an air bubble bursting at water surface and result in the emission of two types of droplets: film drops and jet drops. Only film drops take part to the formation of EAF dust, jet drops are too big to be exhausted and fall back into the liquid bath. We have also shown that the amount of film drops decreases with the size of the parent bubble. When the bubble size reaches 4.5 mm, no film drop is emitted. The bubble size is therefore a key parameter for the reduction of dust produced in EAF.

The continuation of the present piece of work will consist in studying the influence of a slag at the surface of the bath, as well as that of surfactants, on the bubble-burst process.




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