Development of slag alternatives for paste backfill operations

Paste backfilling, a critical step of the underground mining cycle which enables both increased resource recovery and provides a resilient tailings storage solution, is increasingly challenged by limited availability of industrial byproduct binders such as ground granulated blast furnace slag (GGBFS). The use of high quality GGBFS has proven to be critical for operators to address challenges posed by unique and complex ore compositions such as high sulphate ores while also contributing towards reducing the scope 3 greenhouse gas (GHG) emissions, especially as traditional cement binders can be responsible for up to 70% of the GHG emissions in the backfill process. This paper focuses on the development of a versatile engineered lime-based binder for paste backfill which maintains a low GHG footprint and can be made adaptable to various mine conditions, such as high sulphate ores, without compromising strength and other performance requirements. The novel binder has been tested in laboratory conditions by monitoring the unconfined compressive strength development over time using a sulphate-rich paste tailings provided by a commercial mining operation in Canada and has shown promising progress as a slag alternative.