Acid Recovery

Using conventional methods (without the Goemapur Al design), the anodizing bath is partially drained, the waste neutralized and the bath refilled with new electrolyte. This ensures that the concentration of aluminium remains between 10 and 15 g/l, but incurs chemical costs for acidic waste neutralization (for which caustic soda is required) and electrolyte refill (topping up the bath with sulphuric acid). If the aluminium concentration remains constant,considerable chemical savings may be made.

As the concentration of aluminium in the acid electrolyte bath increases, so too does resistance. Current density falls since the anodizing process (itself a function of current) becomes less efficient. To keep the current density constant, voltage must also be increased as aluminium concentrations rise. This increases energy consumption. If the aluminium concentration remains constant, significant savings can also be made in terms of energy consumption.

Using a Goemapur Al unit, the volume and strength of acidic waste is considerably reduced, as is the need to neutralize waste electrolyte using expensive chemical supplements (caustic soda). Using the Goemapur Al process, a small quantity of weak acidic aluminium sulphate is produced near continuously, rather than the occasional, much larger volumes of more strongly acidic spent electrolyte. Waste products for the Goemapur Al process are simpler and cheaper to dispose of; this may be a particularly important consideration for those who do not have their own wastewater treatment plant on site. 

Even aluminium oxide layers result from a constant current-voltage relation, offering an additional guarantee of quality.