Fly ash produced from coal-fired power stations
could be a valuable source of alumina, processed
via caustic potash
Caustic potash, or potassium hydroxide, is a mineral derivative that acts as an important feedstock for numerous potassium-bearing chemicals and is present in many soft and liquid detergents. The precursor of potassium carbonate, in addition to potassium phosphate and many other potassic chemicals, its main competition comes from caustic soda (NaOH) with which it can be used interchangeably in various applications - the latter often preferred by industry owing to its lower cost.
The reason why caustic potash (KOH) is so expensive is not only because of the current high price of potassium chloride (KCl), nor because of the power required for electrolysis, but because of the extremely high costs of purification - heavy metals down to ppb level - of the KCl solution fed to the electrolytic cells. This is owing to...