Research status and prospect of gold leaching in alkaline thiourea solution

Abstract

In this paper, fundamentals, development and the recent research progresses of gold leaching in alkaline thiourea solution, which is the most prospective substitute for dissolving gold in cyanide solution, are reviewed. The mechanism of gold dissolution is the theoretical foundations for gold leaching in thiourea solution. The suitable oxidant should be the substances with moderate redox potential. An efficient stabilizing reagent selected for alkaline thiourea must be satisfied with two conditions: i.e., easily forming hydrogen–sulfur bond and a stable orbicular structure with thiourea molecular in alkaline medium. A series of electrochemical behaviors, adaptability to leach different gold ores and the correlative fundamentals have been studied in detail, gold leaching rate has been improved to 82.68%, the selectivity of gold dissolution has been anatomied based on complex theory. At present, the dissolution process and mechanism are not very well understood, the leaching rate is still lower than that of cyanidation and further studies are needed. It should be believed that gold leaching rate would be improved on a large degree when the key questions are resolved. These fundamentals are of vitally importance that gold leaching in alkaline thiourea solution quickly, high-efficiently and nontoxically will be realized industrially and successfully, translation of this new method into productivity will be quickened, widely industrial application of alkaline thiourea will be propelled, and persistent and harmonized development of gold industry will be accelerated.