what is the difference between dross and scale?

Answer Posted / nihar ranjan

Dross is a mass of solid impurities, which forms during smelting of low-melting point metals viz, Aluminium, Tin, Lead . As metal is melted, it oxidizes, forming a layer of scum and impurities which float to the surface as the metal heats up.

Scaling is mainly due to the presence of calcium and magnesium salts (carbonates or sulphates), which are less soluble hot than cold, or to the presence of too high concentration of silica.

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