Environmental desulphurization of four Canadian mine tailings using froth flotation

Environmental desulphurization is an attractive alternative for management of acid generating tailings. This process placed at the end of the primary process treatment circuit will reduce a large amount of the problematic tailings by concentrating the sulphide fraction. To produce desulphurized tailings, non-selective froth flotation is the most adapted method. The desulphurization level is fixed by the sulphide content of the tailings and their neutralization potential (NP). The final residue should have enough NP to safely compensate for its acidity potential (AP). In this paper, the authors present the results of a battery of tests conducted in Denver cells to study the sulphide flotation kinetics of four different mine tailings samples which contain 2.9 S%, 3.4 S%, 16.2 S% and 24.2 S%, respectively. Tailings P, M, and G are cyanide free and can be floated at pH values of less than 10 by using amyl xanthate as the collector agent. However, tailings D, which come from a gold cyanidation process, did not provide good sulphide recovery because of pyrite depression (even after cyanide elimination followed by a sulphide surface activation and a pH decrease). To successfully overcome this problem, amine acetate was used. This collector allows easy flotation without a pretreatment stage. Dosage of the two type of collector were optimized for the tailings studied. The results of all kinetic tests and collector dosage optimization were combined to establish a model which will estimate the cost of desulphurization. A preliminary analysis shows that the expense of the implementation of this desulphurization technology is comparable to other rehabilitation methods. (C) 2000 Elsevier Science B.V. All rights reserved.