Introduction

Green aluminium production based on scrap melting is now essential in the aluminium market. Melting contaminated scrap can present quality, environmental and yield issues. The dross generated by this process is contaminated with carbon and tends to burn, even violently. This is a safety, environmental and economic problem. Thermised dross has virtually no value, because the dross combustion ends with the almost complete oxidation of the aluminium contained in it. In conclusion, preventing the ignition of the dross or stopping its thermisation brings multiple benefits.

Foundry Ecocer’s endothermic fluxes

The oxidation of aluminium is a highly exothermic reaction, meaning it occurs with a significant release of heat; it can be considered a “combustion” in which aluminium acts as a fuel. The idea of Maurizio Sala, president and founder of Foundry Ecocer, was to use that heat to boost reactions that, from an energetic perspective, move in the opposite direction; these are “endothermic” reactions, which occur by absorbing energy. In this way, it is possible, within certain limits, to limit the temperature rise of the dross, preventing combustion from self-powering in an uncontrolled way.

This brilliant idea has resulted in several chemical formulations based on substances capable of endothermic reactions. Foundry Ecocer has specifically developed two categories of fluxes based on the same principle: fluxes that limit the ignition of dross inside the furnace and fluxes that stop the underway combustion of dross outside the furnace.

The first category includes Rockflux® 190, 191, 192 and 193, with progressively increasing degrees of endothermicity and produced in the form of Rockflux®, Foundry Ecocer’s typical and exclusive small tablets; the second category includes Foundry Quench 193 in powder form.

The reasons behind the adoption of two different forms for the two families of fluxes are as follows:

• Rockflux® fluxes are chemically more stable than granulates and powders, and therefore, the endothermic reaction can take place in the furnace for a longer time; vice versa, the powder shape provides the best covering power.
• Rockflux® is loaded into the furnace along with the scrap; the Foundry Quench is poured onto the burning dross when it is in the pots. This product forms a stable and homogeneous layer that isolates the dross from oxygen and, at the same time, reacts endothermically (and without emitting irritating fumes), leading to rapid quenching and cooling of the dross within a few hours.

In conclusion, Foundry Quench acts as a fire extinguisher, an additional safety for the operators who treat the dross.