This bulletin discusses common problems in the disposal of tailings at mines, quarries and other industries, and identifies safe methods of designing and operating dams and impoundments. The problems encountered at the end of operations when it becomes desirable to end tailings dam construction and it is necessary to rehabilitate the dam and its impoundment to make it permanently safe and environmentally acceptable are discussed and a final chapter describes some of the governmental regulations controlling tailings dams in some countries.
Rio Tinto Iron Ore operates 16 different mine operations in the Pilbara region of Western Australia. Across these operations, there could be more than 100 operational open pits at any given time. This poses a considerable challenge for the effective management of geotechnical risks with finite resources. There are also a number of external legislation and internal compliance requirements that need to be adhered to. A number of standardised systems and tools have been developed by the geotechnical teams to manage the geotechnical risks and this paper introduces the different components of Rio Tinto Iron Ores geotechnical management System (GMS). The GMS covers the complete process, from the geotechnical design of a slope, through implementation to verification of performance and feedback to the design engineer. The focus of the paper will be on the Geotechnical Risk and Hazard Assessment Management System (GRAHAMS) which is used to assess and document the safety and economic geotechnical risk assessments of different slope areas. A number of reports and visual summaries of the risk assessments are available in the system, offering leaders the opportunity to identify areas of elevated risk and allocate resources accordingly. Details of realised risks (geotechnical hazards) are also captured and GRAHAMS provides a process to communicate the hazard and relevant controls to operational personnel. The GRAHAMS system was recently enhanced, moving from a Microsoft Access front-end to a web-based platform. This will enable a number of system improvements to further increase its effectiveness.
It took five years to bring mining with paste backfill to Maaden Barrick Copper Companys (MBCC) Jabal Sayid Mine in Saudi Arabia. The work involved various studies, multiple test programs, site visits for benchmarking and detailed engineering before the paste system was commissioned in October 2017. Barrick is a world leader in paste backfill and drew on international teams to conceptualise, design and construct this 225 m3/hr cemented paste backfill system. Value engineering, peer reviews and risk management workshops were held throughout the process to ensure MBCC received value for money and a reliable system. The paste plant was required to handle a tailings stream that was originally planned to produce hydraulic fill (the coarse fraction) but through the reintroduction of fine tailings was able to generate a good paste product that met mining needs. Challenges involved getting the most out of the tailings dewatering circuits (both fine and coarse streams), the local conditions (temperatures >50°C), large bulk stopes fed by a gravity system and the capital cost associated with building a high throughput system with significant cement storage. This paper presents the history of the project, test work, engineering design and construction, commissioning, and training required to fill the first stope. More recent backfill monitoring, data logging, improvements and ongoing optimisation of the system that have continued through the first year of paste production are also presented.