Several alkaline materials were studied with regards to their ability to form stable suspensions withwater. Gravitational injection of alkaline materials were performed into weathered mine waste in two differentpilot scales (25 L and 1 000 L). When water was added after injection lime mud (LM) was flushed out whilelime kiln dust (LKD) and green liqour (GLD) remained within the mine waste. Deconstruction of the pilot sys-tems showed that both materials had penetrated the voids present. LKD and GLD increased pH significantlyand reduced trace metal concentratios. It is concluded that both LKD and GLD are suitable for stabilizing acidgenerating mine waste.