| 摘要 |
<p>Lead impurity is removed from a nonferrous metal or alloy by immersing the metal or alloy in divided form in a bath, at room temperature, which comprises water, nitric acid and a substance capable of modifying the surface tension of a liquid, 50-100 Kgs. of bronze, brass or aluminium cuttings from machine tool operations may be treated by immersion in a bath of the following composition: water 10 litres; nitric acid (36 DEG Baume) 10 litres; alkyl sodium sulphate 0.5 litre. The bath may be agitated by mechanical means or by air or other neutral gas or the vat p containing the bath may be put under pressure and the liquid circulated by means of a pump. The vat is preferably made of, or internally coated with, cement or ceramic material.</p> |
