| 摘要 |
<p>A bath for removing a magnetite film from a metal surface comprises an aq. soln. of a mineral acid, alkylpyridinium chloride and an amt. of soluble cyanide complex greater than that required for reaction with all the ferric ions in the film to form an insoluble cpd. Pref. the cyanide complex is present in amt. at least 1.5 (esp. 2-10) times the required amt. The bath is useful for cleaning cast iron or steel installations e.g. carbonation columns in soda and caustic cleaner prodn., sodium bicarbonate crystallisation reactors, boilers, steam generators in nuclear plant and electrolysis cell steel cathodes having worn magnetite coatings. The bath removes magnetite films effectively, even at ambient temp., without attacking the underlying metal and will also remove lime scale and sodium bicarbonate deposits.</p> |
