METHOD FOR PRODUCING A CONCENTRATED AQUEOUS SODIUM HYDROXIDE SOLUTION AND FOR TREATING A SODIUM CARBONATE PURGE

摘要

Concentrated aqueous sodium hydroxide solution comprising: at least 25 wt % NaOH, and at least one soluble salt, said soluble salt comprising at least one of the following elements: As, Ba, B, Ca, Co, K, Li, Mg, Mo, P, Pb, Se, Si, Sr, Te, Tl, Ti, V, W, and the at least one of said elements being in specific concentrations ranges. And a process for producing such concentrated aqueous sodium hydroxide solution by treating a purge stream comprising sodium carbonate or bicarbonate.