Cemented Rockfill, Hydraulic Fill, and Paste Backfill
Underground mining operations often include mine backfill. The three most common techniques are cemented rockfill (CRF), hydraulic fill (HF) and cemented paste backfill (CPB). Depending on the geotechnical requirements, the materials are mixed with varying amount of cement binder to provide the required strength. Uncemented fill (such as uncemented rockfill) is also commonly practiced to minimize the cost of removing development waste rock from the underground. In some cases, these backfill techniques are applied for mine remediation. For example, a mix of paste backfill and self-leveling concrete were used to stabilize the arsenic chamber underground at Giant Mine in Northwest Territories, Canada. Clearly, each of the three types of backfill techniques have its advantages and disadvantages. Sometimes a trade-off study is useful to identify one or a combination is most suitable for a specific application. In our experience, CAPEX is not always the best indicator for selecting a backfill method. Other factors such constructability, operability, OPEX, safety, environment, and society are important to consider.