Used 22,500 TPY Sodium Cyanide plant immediately built in 1995. The purpose of the process is to manufacture sodium cyanide of a purity suitable for use as an intermediate for further chemical manufacture such as Dyes, Vitamins, Chelates etc.
Caustic NaCN solution is produced with hydrocyanic acid which is fed into the crystallizer cycle and with sodium hydroxide solution (50 wt. %) which is added via the crystallizer. The reaction takes place within the crystallizer cycle (pos. 5103)
The heat required to evaporate the water of the caustic NaCN solution is added to the crystallizer cycle at the steam-heated reboiler (pos. 5102). Before the vapor leaves the crystallizer at its top, it is washed with fresh sodium hydorxide solution and is almost entirely free of hydrocyanic acid. Liquid droplets are carried along with the vapor condensers (pos. 5201 and 0502). The condensation is achieved with vapor condensate which is recycled and cooled on plate heat exchangers (pos. 5211 or 5212). One of the heat exchanger is cooled with cooling tower water and the other with chilled water. Since the pressure of the cooling tower water and chilled water is higher than the pressure of the vapor condensate, the condensate cannot get into the cooling media.