Bruno Bussière

Chemical factors that influence the performance of mine sulphidic paste backfill

Sulphide-rich tailings from four Canadian mines were sampled (Mines A1, A2, B and C) to prepare several different paste backfill mixtures. The sulphur grade within these tailings samples range from 5 to 32 wt.%. The binders used were Portland-cement-based binders, fly-ash-based binders and slag-based binders with proportions ranging from 3 to 6 wt.%. The study was carried out in two stages. Stage I allowed us to understand the effects of binder type, binder proportion and tailings properties on compressive strength development of paste backfill during the course of curing time. It was pointed out that for high sulphide tailings, neither the slag-based binders nor the fly-ashbased binders were effective, whereas the sulphate-resistant-based binder (mix of Type I [TI] and Type V [TV] Portland cements) gave good long-term strength. However, the slag-based binders gave the best strength for low and medium sulphide-bearing tailings for which the Portland- and the fly-ash-based mixtures have a relatively low strength. Stage II allowed us to study the early stage strength acquisition of the various mixtures. It was found that the chemical composition of the mixing water plays a role on the mechanical behavior of certain cemented backfills. D 2002 Elsevier Science Ltd. All rights reserved.

Environmental desulphurization of four Canadian mine tailings using froth flotation

Abstract 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.