Abstract
The increase of mining tonnage throughput and the variation of tailings mineralogy in a mature mining complex can bring new challenges to underground operations that depend on cemented paste backfill (CPB). The LaRonde mining complex in the Abitibi region (Qc, Canada) is facing this challenge as the mill throughput includes an increasing proportion of satellite zone material to the Volcanic-Massive-Sulphides (VMS) ore. The inclusion ore from the LZ5, 11-3 and Frange zones introduced new geometallurgical tailings signatures that can vary daily and affect the backfill operation and the overall CPB strength development.
Historically, LaRonde VMS tailings consisted of various silicate (Quartz, Aragonite, Chamosite), sulphates (Gypsum) and a large proportion of sulphides, with up to 27.5% of pyrite. This tailings mineralogy did not significantly affect backfill quality. It is inert at early curing age and did not affect the hydration dynamics of cementitious reactions. When LaRonde started introducing a low proportion of LZ5 ore, there was a significant increase in phyllosilicate content that was not caught immediately. Use of this new tailings mineralogy, combined up to 20% chlorite and up to 25% muscovite, significantly affected CPB strength development. Depending on the ratio of LaRonde and LZ5 tailings, the required binder percentage had to be increased to achieve the same UCS strength.
This paper will cover how variability in tailings mineralogy in a mature mining complex can impact the cemented paste quality and how operational lessons-learned and data analytics were used to restore the backfill quality.