Preparation of High-Purity Silver from Waste Fixer

Abstract

The present invention discloses a purely chemical, non-electrical process for preparing high- purity metallic silver from radiographic clinic fixer waste and photographic processing solutions. The process comprises alkaline precipitation and sulphide conversion of dissolved silver to form an insoluble silver-containing sludge, chemical purification of the sludge using nitric acid to remove non-silver impurities, and thermal fusion of the purified silver using borax as a flux. The method operates without electrical energy or electro-chemical systems and produces metallic silver with a purity exceeding 99.9%, while reducing environmental pollution associated with untreated silver-bearing waste..