976 Figure 6 – Yield stress vs slump test 3.4 Industrial trials and monitoring Based on promising laboratory results, industrial trials were conducted on mine CPB plant. The polymer admixture was dosed via a dedicated pump into the mixers, synchronized with tailings and cement feed rates. The target was to reduce cement dosage from 4 % to 3 % of tailings cake feed rate, while slightly increasing solids content and maintaining comparable pumpability. A long-distance stope with a pipeline length near 1.8 km was selected as the primary trial site. During the trials, the following data were collected: • Paste density and slump at the plant outlet; • Real-time pump pressures along the pipeline; • Observations of flow stability and increased dispersion in the mixer; • UCS of field-cast cylinders at 7, 14, 21, 28 and 60 days. Operational data on cement, water and tailings throughput were used to estimate annualized impacts on cement use reduction, water use, tailings utilization and operating costs. 4. RESULTS 4.1 CPB pumpability and strength development, lab test results Laboratory tests results showed that, when the chemical admixture is used in the mix (different testing dosages 1.6-2.7 liters/m3), it is possible to improve pumpability over time in comparison with CPB mix without admixture (Figure 7), while increasing solids content (1.5-3%), reducing cement content by 25%, reducing water use by 4-10% and increasing tailings use by 6-9% (Table 2). Table 2 – CPB lab mix trials Paste Mix Design DP-01 DP-02 DP-03 DP-04 Percent solids (%) 74.7% 76.2% 77.1% 77.7% Dry weights dosage per m3 HS Cement (Kg) 65 49 49 49 Water (Kg) 507 487 470 458 Tailings (Kg) 1426 1512 1533 1549 Admixture (L) - 1.6 2.2 2.7 Admixture dosage mL/ton Sika® Stabilizer MF 701 - 800 1064 1317 Paste density (t/m3) 2.00 2.05 2.06 2.07
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