| 摘要 |
Pickling process for alloy steels, copper, non-ferrous heavy metal alloys, special alloys, titanium, zirconium, tantalum, etc. employs a nitric acid bath, opt. contg. other acids (e.g. hydrofluoric acid), to which urea or an aq. urea soln. is added, the urea supply being metered directly by a NOx detector, operating continuously in the exhaust gas conduit, and a regulator (e.g. as P.I (0/0)
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