Process for producing hydrogen fluoride from an aqueous hydrofluorosilicic acid solution

A process for producing hydrogen fluoride from an aqueous hydrofluorosilicic which comprises:

• i. reacting potassium fluoride and silica with said aqueous hydrofluorosilicic acid solution according to the equation:
• 3KF + H.sub.2 SiF.sub.6 + 0.5SiO.sub.2 .fwdarw. 1.5K.sub.2 SiF.sub.6 + H.sub.2 O
• to form potassium fluorosilicate;
• (ii) reacting said potassium fluorosilicate with ammonia in water according to the equation:
• ##EQU8## to form an aqueous mixture of ammonium fluoride, potassium fluoride;
• and silica
• iii. heating said ammonium fluoride in aqueous solution in the presence of potassium fluoride according to the equation:
• ##EQU9## to release ammonia and to form potassium bifluoride;
• iv. recovering said potassium bifluoride as a solid from solution;
• v. reacting said potassium bifluoride with sodium fluoride according to the equation:
• ##EQU10## bifluoride and any aqueous potassium fluoride solution;
• and vi. heating said sodium bifluoride to release hydrogen fluoride and form sodium fluoride.