Abstract: A method for reclaiming gold in metallic form from gold-containing scrap, including gold-containing base metal alloys and articles in which base metals are at least partially covered with a layer of gold. The method includes the steps of exposing the gold-containing scrap under an inert atmosphere to a leaching solution. The leaching solution has dissolved therein an oxidizing agent including metal ions capable of assuming at least two oxidation states, a portion of the metal ions being in the higher of the two oxidation states. The leaching solution also contains a complexing agent including halide ions in aqueous solution. By so exposing the gold-containing scrap to the leaching solution, base metal contained therein is dissolved to leave a solid metallic residue enriched in gold. The solid metallic residue then is collected mechanically.

Abstract: An improved method and apparatus are disclosed herein for cryogenically cleaning and restoring sandy beaches which have become contaminated by oil spills. In the method, a mixture of particulate, pulverized and recycled rubber and wood fines is applied to the contaminated area for absorbing the oil prior to cryogenic treatment. The absorption of the oil by the particulate rubber and wood enhances the solidification during the cryogenic treatment. In the apparatus, a hopper is mounted to a beach cleaning vehicle forwardly of a liquid cryogen spray head. The hopper is constructed to receive and discharge particulate absorbent before the contaminated area is contacted by the liquid cryogen.