Aluminum Chloride Production

The process under analysis comprises three major sections: (1) Reaction; (2) Crushing and sizing; and (3) Scrubber.

Reaction. The reaction takes place in ceramic-lined, tube-shaped reactors containing molten aluminum. The chlorine gas is injected below the surface of the molten aluminum pool, leading to the formation of aluminum chloride vapors in a highly exothermic and practically instantaneous reaction. The reaction occurs at 670 – 850°C and the temperature is maintained in this range by the control of chlorine and aluminum admission rates and by cooling reactors walls with water. The AlCl3 vapor from the reactors is fed to air-cooled condensers, which are vertical cylinders with conical bottoms. As the aluminum chloride vapor gets in contact with condenser walls, it loses its heat of sublimation, and gets deposited in the walls. Such deposited solid is withdrawn from the condenser walls at regular intervals, and subsequently conveyed to holding silos.

Crushing and sizing. The aluminum chloride crystals from the holding silos are crushed and sized by sieving under a dry air atmosphere. After sizing, aluminum chloride product is obtained.

Scrubber. The condensing, crushing and sizing operations, as well as storage facilities, are designed to avoid the entrance of moist atmospheric air. In this way, a vent system tied to such pieces of equipment directs the off-gas removed, containing unreacted chlorine and uncondensed gases, to a caustic scrubber. The scrubbed gas is vented to the atmosphere, while the scrubber’s bottom stream comprises wastewater.