34 • Showcase a collaborative innovation model between a mining company and a technology provider, focusing on documented engineering contributions rather than promotion of specific products. The scope covers tailings characterization, state-of-the-art review, laboratory mix design, industrial trial implementation and interpretation of technical, sustainability and economic results. 2. BACKGROUND AND STATE OF THE ART 2.1 Cemented Paste Backfill and sustainability CPB is widely used to backfill underground voids with a mixture of dewatered tailings, water and hydraulic binders, providing ground support and allowing higher extraction ratios. Numerous studies have shown that CPB helps reduce the area, volume and risk of surface tailings impoundments and can improve overall mine stability and safety. At the same time, lifecycle assessments identify cement use in backfill as a major contributor to embedded greenhouse gas emissions due to the energy-intensive clinker production process. Optimizing binder content without compromising strength is therefore a key decarbonization lever. Recent research and field practice have highlighted three main avenues for more sustainable CPB: (i) optimizing mix design to reduce cement and water demand; (ii) partially replacing Portland cement with alternative binders or supplementary cementitious materials; and (iii) using chemical admixtures to decouple rheology from water content, enabling higher solids contents and lower water-to-cement ratios while maintaining pumpability and stability. 2.1 Sulfide-rich tailings and admixture use Sulfide-rich tailings, such as those from base-metal deposits, pose specific challenges: high sulfur contents and reactive minerals can lead to sulphate generation, delayed ettringite formation, swelling and strength loss if mixes are not properly designed. Fine particle size distributions increase specific surface area and typically push both water and cement demand upwards. For these materials, simple increases in cement dosage can control early strength but at a disproportionate cost in CO₂ and operating expenditure. High-range water-reducing and rheology-modifying admixtures originally developed for concrete, have increasingly been evaluated for CPB. The formulations have been adjusted to adapt to the effects of the pernicious phases and Particle Size Distribution (PSD) variability of different tailings. Laboratory and field case studies show that they can maintain CPB pumpability (yield stress/slump) at a higher solids content, allowing lower water contents and improved strength efficiency. Translating these benefits from controlled tests into long-distance backfill systems with complex piping and variable tailings remains an area where mine-specific trials and partnerships are essential. 3. MATERIALS AND METHODS
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