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1 INTRODUCTION The use of paste backfill is currently practiced in many modern mines throughout the world,

The use of paste backfill is currently practiced in many modern mines throughout the world,
particularly in Canada and the United States because of increasingly stringent environmental
regulations (Weaver & Luka 1970, Barsotti 1978, Viles & Davis 1989, Petrolito et al. 1998).
Paste backfill is a hardened composite material made from a mixture of mine tailings, hydraulic
binders (such as ordinary Portland cement, fly ash, blast furnace slag or a combination of these)
and water. The two main benefits of paste backfill are lower operating costs and a reduction in
the amounts of waste material sent to the tailings facility for disposal. This reduction of the
amount of waste sent to the tailings facility decreases the environmental impact and decreases
future capital expenditures related to the tailings facility (Barsotti 1978, Landriault & Tenbergen
1995, Hassani & Archibald 1998). Because the role of hydraulic binders is to generate mechani-
cal strength, one of the challenges is the use of cemented paste backfill as secondary pillars, to
ensure the stability of the underground excavations (Thomas et al. 1979, Mitchell & Wong
1982, Mitchell 1989, Stone 1993, Amaratunga & Hein 1997, Ouellet et al. 1998, Petrolito et al.
1998). A number of studies which have been published in the last 10 years have allowed a better
understanding of the properties of paste backfill (Ouellet et al. 1998, Benzaazoua et al. 1999a &
b, Bernier et al. 1999). These previous works have indicated the influence of many of the pa-
rameters on paste backfill which affect short-term and long-term strength acquisition. Some of
these parameters are tailings mineralogy and particle size distribution, moisture content, binder
type and proportion, the degree of saturation and finally, chemical weathering (e.g. Benzaazoua


Source: Aubertin, Michel - Département des génies civil, géologique et des mines, École Polytechnique de Montréal


Collections: Engineering; Environmental Management and Restoration Technologies