This paper presents an optimisation loop that looked to improve how Newmonts Tanami Operations (NTO) determines its required stable stope strengths. In order to do this, a comparison exercise was completed, in which NTOs current stability assessment method was compared to other popular assessment methods ranging from analytical to numerical methods. From this comparison, it was decided to proceed with a different stability assessment method that uses shear stress reduction. The paper then presents how the use of this method was implemented and presents three case studies on how the new stability assessment method has benefited NTO.
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.
This paper addresses issues related to understanding, managing and communicating geomechanical mining risk at all decision levels of a mining company. The focus is on how different risk analysis tools and procedures can be used effectively, while also highlighting limitations of some of the most popular tools. A strong case is made for a critical assessment of the effectiveness of risk-management tools. Finally, the paper discusses the challenges of understanding and communicating geomechanical mining risk, given the asymmetry of knowledge and information by decision-makers in mining companies.