Application of Geotextile on Slope Stability for Establishment of Tailings Dam in Gold Mines – The Case of Hidden Valley Mine, Papua New Guinea

1. Introduction

The Hidden Valley (HV) tailings dam/storage facility (TSF – Fig.1) is constructed with downstream method of embankment. The initial dam crest elevation was designed for RL 2,000 with a storage capacity of 40Mt of tailings with a mill throughput of 4.2Mtpa, (Rynhoud et al., 2017). The TSF has reached its designed capacity at RL 2,000 and the mining company plans to raise the dam height to RL 2,015 to increase the volume. In this study, it proposes for further 20m dam height expansion in two stages (RL 2,025 & RL 2,035) with the application of geotextile reinforcements for slope stabilization.

Fig.1 Hidden Valley (HV) tailings dam

2.Numerical Simulation

Analysis of the TSF is carried out in 2 cross sections (Fig.2) with 4 stages (stg): RL 2,000(stg.1), RL 2,015(stg.2), RL 2,025(stg.3), RL 2,035(stg.4). Phase2 software is used for numerical simulations with: (1) no reinforcement; (2) geotextile reinforcement. Desired critical shear strength reduction factor (SRF) is 1.3 and above.

Fig.2 Model view of section AA' and BB' at RL 2,000

3. Results, Discussion and Conclusion

Fig.3 Stability of dam at different RL with no support

Fig.4 Stability of dam with reinforcements at different RL in X2

Fig.5 Effectiveness of reinforcements at RL 2,000 (X1)

It is unstable at initial stage with no support in X1(Fig.3). Geogrid and Geocomposites are unstable in X1, whereas structural interface is stable in X1(Fig.5). In X2, it is stable at initial stage, but unstable as the dam height increases (Fig.3). Geogrid and Geocomposites are stable at initial stage but, unstable as dam height increases (Fig.4). Structural interface is consistent and stable (Fig.4).

RL 2,035 is possible to achieve with the application of geotextile reinforcement in structural interface for stability in both X1 and X2.

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Study of Slope Stability of Tailings Dam Height Expansion from Elevation (RL) 2000m to RL 2035m at Hidden Valley Mine, Papua New Guinea

 ABSTRACT

The tailings dam height expansion from the initial RL of 2000 m to 2035 m at Hamata Tailings (Dam) Storage Facility (TSF) at Hidden Valley Mine in Papua New Guinea pose some risks in terms of slope stability conditions. In this study it is proposed to analyse the TSF at four stages. i.e.RL 2000, RL 2015, RL 2025 and RL 2035. Based on the design parameters and material properties, this study utilizes Phase 2 software to analyse the slope stability conditions of the TSF. The embankment construction methodology in stage 1 is downstream whereas the other stages (2-4) are upstream method of construction. Numerical Simulation (Modeling) of the TSF is done in four stages (1-4) with three parameters, (1) Simulation without Reinforcement; (2) Simulation with Reinforcement (s); and (3) Simulation with Seismicity. Simulation result(s) that give Critical Shear Strength Reduction Factor (SRF) of 1.3 or above is/are ideal for consideration in this study. The findings in this study is somewhat useful for the mining company for future height expansion plans for the TSF and also it is helpful to government for assessment purposes for future TSF height expansion proposals. Future Researchers may analyse other safety aspects not covered in this study.

 Keywords: Tailings dam, slope stability analysis, Dam Height expansion, embankment, Shear Strength Reduction Factor(SRF), RL-Reduced Level(m), downstream construction method, Upstream Construction Method. Phase 2 Numerical Simulation, Reinforcement, Seismicity.

 

Google image of Hidden Valley TSF

Note: Full paper for this abstract  is ready and can be accessed upon request via contact form in this website.

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