Innovative process for the recovery of gold from mining waste

The metals and industrial minerals contained in the tailings produced by mining and quarrying activities, are cause of environmental damage. The objective of this experimental work is the application of innovative technologies for the treatment and exploitation of mining tailings in Romania, in order to recover materials high grade raw to be placed on the market, reducing the volume of the wastes. The study is focused on hydrometallurgical process for the recovery of gold. The innovative treatment chosen is the thiosulphate process that, compared to conventional cyanide, has several advantages, first of all the most eco-friendly and non- toxic to humans. The conventional processes - such as cyanidation - show operating limits in the case of auriferous minerals refractory materials, such as Romanian wastes object of the study. Another fundamental characteristic of the ammoniacal thiosulphate solutions, is the best selectivity towards gold, not attacking the majority of the gangue mineral constituents. The objective of the investigation, is to optimize some parameters relating to the dissolution of gold and the subsequent recovery from purified solutions, determining beforehand the technical feasibility of the scheme of process developed on a laboratory scale. The dissolution rates of gold reached a final value of 65% Au – working at room temperature - with recoveries of the global process of about 65%, in line with the conventional process.