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Home > The factors that effect oxidation loss in the aluminium melting

The factors that effect oxidation loss in the aluminium melting


1 The oxidation loss degree depends on the affinity between metal and oxygen and the metal surface oxidation film property


The affinity between aluminium and oxygen is big, but oxidation film α >1, so the oxidation loss is not too much.


In the melting, the surface active elements that have good affinity with oxygen will be oxidized in the first priority, or be oxidized with the base metal at the same time.  In this process, the property of alloy elements oxides and base metal oxides will control the whole alloy oxidation process.


2 Melting temperature

The effect law for melting temperature is metal oxidation speed is small as the temperature is low, the oxidation will speed up in the high temperature. Because the materials diffusion will augment in high temperature, the oxidation film temperature decrease, the linear expansion difference between oxidation film and metal increase, so the oxidation film will break. 


3 The property difference of furnace gas has different effect for oxidation loss


As the melting furnace structure, heating source and fuel burning degree are different, there is different proportion O2,  H2O, CO2,  CO, H2,  CmHn, SO2,  Netc gas in the furnace gas.  Whether these gases make the metal oxidized or not is subject to the interaction between furnace gas and metal.


4 Aluminum melting furnace type


Different type aluminium melting furnace will effect oxidation loss in the melting.  As different melting furnace type, its molten pool, area and heating mode will be different.  For example, low frequency (LF) induction furnace melt aluminium alloy, the oxidation loss will be 0.4%-0.6%, electric resistance reverberatory oxidation loss is 1.0%-1.5%, flame furnace oxidation loss is 1.5%-3.0%.


5 Furnace charging, furnace feeding materials

Furnace charging condition is one important and considerable factor that effect oxidation loss.   The smaller furnace charging lump, the bigger area will be, the oxidation loss will be more serious.   In general, aluminum ingot burning loss will be 0.8%-2.0%; the baled sheet scraps burning loss is 3%-10%, chipping scraps maximum burning loss can reach to 30%.


6  In the fixed other conditions, the longer meting time, the bigger oxidation loss will be.


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