Hollow fiber membrane technology for removal and recovery of cyanide from process solutions

Removal of cyanide from process solutions and wastewater is important to maintain the quality of water resources. Cyanide, one of the most toxic of compounds, is widely used in gold leaching operations due to its ability to form water soluble complexes with gold, silver, copper and other metals. Several methods being used in the industry, such as alkaline oxidation, photochemical dissociation, sulfur dioxide catalyzed oxidation, and others, destroy cyanide present in the process solutions before their surface discharge, except the idification-Volatilization-Reneutralization (AVR) technique, which recovers cyanide by acidification of cyanide-containing solutions, causing generation of hydrogen cyanide gas, which is reneutralized in sodium hydroxide solution. A similar technique for removal and recovery of cyanide using hollow fiber membrane modules has been investigated to study the effect of operating parameters upon its performance in cyanide removal. Hollow fiber membrane modules consisting of hydrophobic polypropylene hollow fibers were tested for their performance in cyanide removal under varying conditions of pH, the flow rates of the acidified feed and the alkaline acceptor solutions, and the temperature of operation and cyanide concentration in the feed solution to determine the optimum conditions of operation. The technology has been tested using a larger module under the optimum conditions derived, with the higher flow rates of the feed and the acceptor solution. The performance of the membrane modules for cyanide removal with