Recovery of hf

Claim 1

THE PROCESS OF PREPARING SUBSTANTIALLY ANHYDROUS HF WHICH COMPRISES CONTACTING, AT TEMPERATURE BELOW ABOUT 30* C., A GAS CONTAING HCI AND AT LEAST 5 MOL PERCENT HF WITH AQUEOUS HYDROFLUORIC ACID SOLUTION OF HF STRENGTH ABOVE ABOUT 60 MOLE PRECENT, CONTROLLING THE HF STRENGTH AND TEMPERATURE OF SAID SOLUTION SO THAT THE VAPOR PRESSURE OF HF ABOVE SAID SOLUTION IS LESS THAN THE PARTICAL PRESSURE OF HF IN SAID GAS, CONTINUING GAS-LIQUID CONTACT FOR TIME SUFFICIENTLY LONG AND IN THE PRESENCE OF A SUFFICIENT QUANTITY OF GAS TO ABSORB SUFFICIENT OF SAID GASEOUS HF INTO SAID SOLUTION TO PRODUCE AN AQUEOUS HYDROFLUORIC ACID SOLUTION OF HF STRENGTH SUBSTANTIALLY GREATER THAN 60 MOL PERCENT AND OF SUBSTANTIALLY NO HCI CONTENT, AND FRACTIONATING THE RESULTING HYDROFLUORIC ACID SOLUTION TO DISTILL SUBSTANTIALLY ANHYDROUS HF GAS THEREFROM.