Method for directly recovering fluorine from gas streams

摘要

This invention is a process for the direct recovery of gaseous fluorine from waste-gas streams or the like. The process comprises passing the gas stream through a bed of anhydrous K3NiF6 pellets to fluorinate the same to K3NiF7 and subsequently desorbing the fluorine by heating the K3NiF7 pellets to a temperature re-converting them to K3NiF6. The efficiency of the fluorine-absorption step is maximized by operating in a selected and conveniently low temperature. The desorbed fluorine is highly pure and is at a pressure of several atmospheres. Preferably, the K3NiF6 pellets are prepared by a method including the steps of forming agglomerates of hydrated K3NiF5, sintering the agglomerates to form K3NiF5 pellets of enhanced reactivity with respect to fluorine, and fluorinating the sintered pellets to K3NiF6.