Process for removing soluble fluoride from a waste solution containing the same

A process for removing soluble fluoride from a waste solution containing said soluble fluoride, and manufacturing hydrogen fluoride from the fluoride so removed, said process comprising:

• (A) mixing said waste solution with an aqueous slurry containing seed calcium fluoride particles to form a first aqueous composition;
• (B) mixing said first aqueous composition with a calcium sulfate containing reagent to form a second aqueous composition;
• (C) advancing said second aqueous composition through a tubular reactor comprising a plurality of parallel tubes having a length and diameter to provide for an effective period of time and at a velocity sufficient to permit said soluble fluoride and said calcium sulfate containing reagent to react and attach to said seed particles of calcium fluoride, said seed particles of calcium fluoride thereby increasing in size to become enhanced particles;
• (D) removing from said second aqueous composition enhanced particles having an average particle size of at least about 20 μm;
• and
• (E) treating said enhanced particles removed in step (D) with sulfuric acid to form regenerated hydrogen fluoride containing less than about 500 ppm chloride and regenerated calcium sulfate.

A process for removing soluble fluoride from a refinery process waste solution containing said soluble fluoride, said process comprising:

• (A) mixing said waste solution with an aqueous slurry containing seed calcium fluoride particles to form a first aqueous composition;
• (B) mixing said first aqueous composition with a calcium sulfate containing reagent to form a second aqueous composition;
• (C) advancing said second aqueous composition through a tubular reactor comprising non-concentric tubes at a linear velocity in the range from about 8 to about 20 times the theoretical Stokes settling velocity based on median particle size, for an effective period of time to permit said soluble fluoride and said calcium sulfate containing reagent to react and attach to said seed particles of calcium fluoride, said seed particles of calcium fluoride thereby increasing in size to become enhanced particles;
• (D) removing a portion of the enhanced particles from said second aqueous composition, wherein said portion contains substantially only enhanced particles having a size greater than about 20 μm;
• and
• (E) removing water from said second aqueous composition, wherein said water removed contains less than about 50 ppm of soluble fluoride.