Sulfuric acid reprocessor

An acid reprocessor at a semiconductor processing station for reprocessing waste oxidant solution containing contaminated H.sub.2 SO.sub.4 from a semiconductor processing operation at said semiconductor processing station, said acid reprocessor comprising:

• an input flask means for receiving said waste oxidant solution containing contaminated H.sub.2 SO.sub.4, light boiling contaminants, particulates and water, said input flask means having an output for outputting said waste oxidant solution;
• a first distillation having an input coupled to said output of said input flask means to receive said waste oxidant solution and having a gaseous output being coupled to a first column packed with a column packing means, a first heating means for heating said waste oxidant solution in said first distillation means to boil off water and other light boiling contaminants from said waste oxidant solution to produce an enriched acid, said light boiling contaminants and water escaping from said gaseous output through said fist column of said first distillation means, an input in said first column to receive reflux liquid which is trickled through said first column to retard loss of H.sub.2 SO.sub.4 in said first distillation means, a feed output from said distillation means for said enriched acid;
• a second distillation means having an input coupled to said feed output for receiving said enriched acid, a second heating means for heating said enriched acid in said second distillation means to boil off substantially pure H.sub.2 SO.sub.4, through a second column leaving an acid waste sludge in said second distillation means, said second distillation means having a first output for providing said substantially pure H.sub.2 SO.sub.4, said first output being coupled to a condenser to condense said substantially pure H.sub.2 SO.sub.4, said second distillation means having a second output for removing said acid waste sludge from said second distillation means;
• a vacuum generation means coupled to said first and second distillation means, providing a reduced operating pressure in said first and second distillation means, such that said particulates remain in said acid waste sludge;
• an ozone generation means to produce ozone;
• an ozone introduction means to introduce said ozone into said substantially pure H.sub.2 SO.sub.4, said ozone introduction means being coupled to said ozone generation means, said substantially pure H.sub.2 SO.sub.4 mixed with ozone being used at said semiconductor processing station for said semiconductor processing operation;
• a waste collection tank providing for removal of said acid waste sludge from said second distillation means through a second output.

An acid reprocessor at a semiconductor processing station for reprocessing waste oxidant solution containing contaminated sulfuric acid (H.sub.2 SO.sub.4) from a semiconductor processing operation at said semiconductor processing station, said acid reprocessor comprising:

• an input flask means for receiving said waste oxidant solution containing contaminated H.sub.2 SO.sub.4, light boiling contaminants, water and particulates, said input flask means including a first heating means for heating said waste oxidant solution, said input flask means having an output for outputting said waste oxidant solution;
• a first distillation means having an input coupled to said output of said input flask means to receive said waste oxidant solution and having a gaseous output being coupled to a first column packed with a column packing means, said first distillation means having a second heating means for heating said waste oxidant solution to boil off said water and said light boiling contaminants from said waste oxidant solution to produce an enriched acid, said contaminants escaping from said gaseous output through said first column and through a mist eliminator means of said first distillation means, said first column having an input to receive reflux liquid which is trickled through said column to retard loss of H.sub.2 SO.sub.4 in said first distillation means, said first distillation means having a feed output for providing said enriched acid;
• a second distillation means having an input coupled to said feed output for receiving said enriched acid, said second distillation means having a third heating means for heating said enriched acid to boil off substantially pure H.sub.2 SO.sub.4, through a second column leaving an acid waste sludge in said second distillation means, said second distillation means having a first output for providing said substantially pure H.sub.2 SO.sub.4, said first output being coupled to a tubular shell of a condenser to condense said substantially pure H.sub.2 SO.sub.4, said condenser having a first coil through which a coolant flows to cool the substantially pure H.sub.2 SO.sub.4 which flows through said tubular shell, said second distillation means having a second output for removing said acid waste sludge from said second distillation means;
• a heat exchanger means having a cooling means including a second coil through which a coolant flows and having a first input coupled to said gaseous output of said first distillation means to receive said water escaping from said first distillation means and having a second input coupled to said second output of said second distillation means to receive said acid waste sludge, said heat exchanger means having a third column packed with column packing means and having an input to receive waste acid which is trickled through said third column;
• a vacuum generation means coupled to provide a vacuum in said first distillation means and in said second distillation means, said vacuum generation means producing a vacuum in said second distillation means to reduce said particulates of said substantially pure H.sub.2 SO.sub.4 ;
• an ozone generation means to produce ozone;
• an ozone introduction means to introduce said ozone into said substantially pure H.sub.2 SO.sub.4, whereby said acid reprocessor provides a reprocessed semiconductor grade H.sub.2 SO.sub.4 and ozone at said semiconductor processing station from waste oxidant solution of a semiconductor processing operation.

A method for reprocessing waste oxidant solution containing contaminated sulfuric acid (H.sub.2 SO.sub.4) from a semiconductor processing operation at a semiconductor processing station, said method comprising the steps of:

• receiving from said semiconductor processing station said waste oxidant solution containing contaminated H.sub.2 SO.sub.4, light boiling contaminants, water and particulates in an input flask means having a first heating means for heating said waste oxidant solution, and outputting said waste oxidant solution from an output of said input flask means;
• first distilling said waste oxidant solution in a first distillation means having an input coupled to said output of said input flask means to receive said waste oxidant solution and having an gaseous output coupled to a first column packed with a packing material comprised of glass rings and a first mist eliminator means coupled to the output of said first column, said first distillation means having a second heating means;
• heating said waste oxidant solution by said second heating means such that water is boiled off from said waste oxidant solution to produce an enriched waste oxidant solution, said water escaping said first distillation means from said gaseous output through said packing material in said first column of said first distillation means and then through said first mist eliminator means;
• refluxing liquid that is trickled through a reflux input of said first column to retard distillation of H.sub.2 SO.sub.4 in said first distillation means, wherein said first distillation means has a feed output for said enriched waste oxidant solution;
• second distilling in a second distillation means having an input coupled to the output of said first distillation means for receiving said enriched waste oxidant solution, said second distillation means having a third heating means;
• heating said enriched waste oxidant solution with said third heating means and vaporizing substantially pure H.sub.2 SO.sub.4 from said enriched waste oxidant solution through a second column leaving an acid waste sludge remaining in said second distillation means;
• collecting a substantially pure H.sub.2 SO.sub.4 liquid after said substantially pure H.sub.2 SO.sub.4 vapor ascends through said second column and a second mist eliminator coupled to the output of said second column and condenses in a condensing means;
• generating a vacuum that reduces the operating pressure in said first distillation means and said second distillation means with a vacuum generation means coupled to said first distillation means and to said second distillation means;
• reducing said particulates of said substantially pure H.sub.2 SO.sub.4 vapor by adjusting said operating pressure, thus decreasing the density of said substantially pure H.sub.2 SO.sub.4 vapor and decreasing the terminal velocity of said particulates, such that said particulates remains in said acid waste sludge;
• generating ozone and introducing said ozone into said substantially pure H.sub.2 SO.sub.4, said substantially pure H.sub.2 SO.sub.4 having ozone introduced therein being used at said semiconductor processing station;
• removing said acid waste sludge from said second distillation means through a second feed output into a waste collection tank.