Ground motion over mine sites, while an everyday occurrence, may represent hazards that need to be identified and monitored over time. An accurate and regularly updated overview of surface movement over mining operations is therefore critical as part of an ongoing risk assessment program. By having a complete picture of ground stability, movement patterns which represent potential geotechnical hazards to safety and mine operations can be identified and tracked over time. From routine monitoring to highfrequency updates, interferometric synthetic aperture radar (InSAR) technology is increasingly being used to identify a wide range of movement patterns which may be of concern to mine operators and geotechnical engineers. Recent advances in radar image processing algorithms, combined with an increase in the number of satellite systems launched into orbit, have resulted in improvements in the ability of this technology to capture complex and rapid displacement. In particular, the ability to characterise rapid and sudden motion (metres of movement) has increased the utility of InSAR from a practical standpoint in characterising geotechnical hazards. Further exploitation of 2D monitoring approaches in capturing vertical and horizontal movement, particularly for producing displacement vectors along cross sections, can also provide additional insights into hazard characterisation. Key differences between the ability of highresolution imagery to capture complex and rapid deformation in comparison to low-resolution (but freely available) Sentinel imagery are also touched upon. This paper will focus on the practical application of InSAR technology to monitor mine sites around the world, illustrating how new processing approaches and data sources are used in the identification of geomechanical risks that are typically of greatest concern from both an operational and safety standpoint. Examples of results over an active mine site will be shared and a particular emphasis will be placed on selecting the right InSAR tool for helping geotechnical engineers best manage risk due to movement.
Traditional paste filling materials adopt industrial solid wastes such as unclassified tailings and waste rocks as filling aggregates, but the binder used is dominantly commercial cement, which raises the filling cost. Hemihydrate phosphogypsum (HPG) is one of the main by-products of the phosphorus chemical industry, and the high-efficiency utilisation technology of HPG has been a problem worldwide. The potential gelling property of HPG is found in the laboratory at first. It is then modified by appropriate chemical and physical methods to produce new filling binder with the purpose of replacing cement completely. A lot of experiments show that the modified HPG (MHPG) has outstanding properties of quick setting (setting time less than 90 minutes), high early strength (UCS for three days more than 8 MPa) and good flowability (yield stress less than 50 Pa). In addition, MHPG can bind different aggregates according to the filling needs to prepare a homogeneous, non-settling, and non-bleeding filling paste. In the past three years, two mines in Guizhou, China have adopted the underground paste backfill technology and surface open pit cemented filling technology based on MHPG paste materials. In practice, this new technology reduces the material cost by 30%, increases the flow capacity by 50%, and has a solid wastes rate of more than 98% compared to traditional methods.