Patent ID: 6872296

Claim:
A method for removing ammonia from a gas comprising HCN, ammonia and water, comprising: a. contacting the gas with a first aqueous ammonium phosphate solution having a first ammonium ion to phosphate ion molar ratio to produce a substantially ammonia-free HCN gas and a second aqueous ammonium phosphate solution having a second ammonium ion to phosphate ion molar ratio higher than the first ratio, said second aqueous ammonium phosphate solution comprising ammonium oxalate and ammonium formate; b. distilling the second ammonium phosphate solution to produce ammonia gas and a third ammonium phosphate solution having a third ammonium ion to phosphate ion molar ratio less than the second ratio, said third aqueous ammonium phosphate solution comprising ammonium oxalate and ammonium formate; c. cooling said third ammonium phosphate solution to produce a fourth ammonium phosphate solution; d. passing said fourth ammonium phosphate solution between at least one pair of electrodes having a DC voltage across said at least one pair of electrodes, capable of generating a sufficient current to oxidize said oxalate and formate to produce an oxidation product comprising carbon dioxide and hydrogen and a fifth ammonium phosphate solution that is substantially free of oxalate and formate; and e. separating the oxidation product from the fifth ammonium phosphate solution.