EDTA disodium salt → Ethylenediaminetetraacetic Acid

Participants

Reaction Steps

An EA-5 fixer solution is treated in the silver recovery unit 200 shown in FIG. 2 which also incorporates a silver precipitating unit 80, according to U.S. Pat. No. 5,437,792 and described above. Silver precipitating unit 80 comprises a vessel 81 which receives untreated EA-5 fixer via line 250 at inlet 49 and is drawn via line 220 at outlet 39 to form a continuous stream of untreated EA-5 fixer flowing at a rate of 100 mls/minute. A solution of 15 g/l disodium EDTA dihydrate and 45 g/l sodium carbonate in storage vessel 210 is drawn off by line 211 by pump 212. The solution is then pumped to line 220 via line 213 and injected at a rate of 100 mls per minute through injection tee 215 into a seasoned and untreated EA-5 fixer solution with a pH of about 4.1, in line 220, flowing at a rate of 100 mls per minute. The resulting solution is then mixed within a tubular reactor 216. The solution is then returned to a silver precipitation unit 80 which employs TMT as a silver precipitating agent, and a flocculant to agglomerate the TMT-silver precipitate, as described above.

Provenance & Evidence