While not specific to tailings, this resource includes valuable knowledge for tailings engineers. Proceedings of a specialty conference on hydraulic fill structures, held in Fort Collins, Colorado, August 15-18, 1988. Sponsored by the Geotechnical Engineering Division of ASCE. This Geotechnical Special Publication (GSP 21) contains 53 papers covering many aspects of hydraulic fill structures with special emphasis on geotechnical issues. The papers present an excellent review of historical development, as well as art and practice of hydraulic fill structures. Topics include: excavation, transport, and deposition; material properties; static and dynamic stability; soil improvement/geosynthetics; new developments, and case histories. Specific areas of interest include historical reviews, dredging technology and dredge spoil disposal, depositional behavior, mine backfill, tailings disposal, slurry pipelines, hydraulic fill properties and behavior, static and dynamic loading conditions, densification and improvement of hydraulic fills, artificial islands, land reclamation, and case histories of successes and failures.
?It has been determined, after a technical feasibility study, that ultrasonic is the best alternative to characterize slurry flows in tailings flumes, by using the Ultrasonic Velocity Profile (UVP) technique, which among its many advantages it has shown not to be invasive, to have a high sample frequency, to have the ability to make measurements in opaque means, to have portability, and also that its implementation in existing structures is not complex, nor that it requires special permissions like other technologies do (based on radiation). In the Investigation Centre JRI (CI-JRI), two measurement UVPs prototypes have been designed, built and set up in transport systems of flumes on a laboratory scale. These prototypes have also been able to perform ultrasonic measurements that have got to a correct estimation of the velocity profile, together with an ad hoc post-processing methodology, outcomes that allow projecting applications at an industrial level and that would generate meaningful benefits in the operation. The future challenges aim to higher scale tests and the development of a given post-processing methodology that would let determine inline, and with a precision over 1%, associated values to the concentration of solids in the fluid, the velocity profile of the fluid in the flume and rheological parameters, all essential to a correct controlling of stages in the transportation of tailing slurries with high concentration.
The perceived need for accurate and reliable methods of measuring suspension rheology in real time arises from the greater demands being placed on mineral processing operations. To extend mine life and reduce TSF footprint the adoption of finer grinds, higher solids concentration and high clay ores result in complex multiphase suspensions that need close monitoring to optimise thickener performance, pipeline transport and tailings deposition. Often the control of the processing or transport of these suspensions can be related to its rheology. However, due to the involved nature of rheological measurement for suspensions and the nuanced interpretation of data necessary to produce useful decisions, rheometry has only seen limited application in process monitoring. A robust unit that can measure, analyse and interpret the rheology of a process stream continuously and unattended is needed. The CSIRO has developed an online rheometer to address this problem. This paper describes the process prior to the deployment of the online rheometer to an Australian goldfield site, comparing online rheological measurement to benchmark laboratory values.
Recent tailings facility failures and the resulting emphasis on ensuring that the best available technology is applied when designing a tailings management system, together with a need to reduce water consumption, have brought about a need for wider evaluation of tailings management approaches. A key determining issue is the extent to which tailings slurry can be cost-effectively dewatered. This issue often drives the selection between high-density slurry, paste and filtered tailings management approaches. Commonly, the focus is purely on thickening, where production rates exceed 30,000 t per day, or filtration, which is most suitable for production rates below 30,000 t per day due to the number of units required, as the means for separating the solids and the liquids. However, there are alternative approaches, suitable for small and medium sized mines, that are not only competitive in terms of capital and operating cost but that may also be significantly more robust and accommodating of variations in ore mineralogy and process plant upsets. These entail the application of hydrocyclones and/or vibratory dewatering screens in conjunction with thickening and/or filtration, sometimes treating only a part of the tailings stream in order to more reliably achieve dewatering targets. The alternative approaches can facilitate more balanced optimisation between the broader drivers of water recovery, slope stability, seepage control and post-closure relinquishment. This paper describes a range of alternative dewatering approaches (in addition to pure thickening or filtration) that merit consideration. It provides insight into the methods of testing and evaluation for selection and sizing of the equipment, describes tailings placement and storage methods associated with varying degrees of dewatering, and discusses the related benefits in terms of robustness of dewatering, water recovery, slope stability, seepage control and post-closure relinquishment.
The technology behind industrial applications such as fluids with high percentage solids continues to evolve, as do the corresponding regulations and specifications that ensure the safety of workers and the environment. Valves make up key aspects of this technology and often represent the single point of failure for entire operations. More often than not, the valves being used in high percentage solids applications are known as severe service valves (SSVs) due to their ability to withstand extreme conditions. Most experts agree that SSVs are identified by applications, and that these applications are challenging to the valves ability to provide a minimum acceptable level of performance over a minimum acceptable duration. This paper serves to determine what the minimum requirements are for SSVs in high percentage solids applications specifically concentrating on paste and thickened tailings.
The disposal of diluted tailings in dams, due to their muddy state, becomes inherently difficult to contain and this poses a high risk to society, as observed in the last two accidents that occurred in Brazil in 2015 and 2019. Therefore, the disposal of coarser tailings becomes more relevant because besides contributing to the reduction of water consumption and environmental impact, it will also require a smaller disposal area. However, to transport a thicker slurry, the viscosity and the yield stress of the tailings will increase. Therefore, for long distance conveying systems, high friction losses are generated in the pipeline. In view of the high operating pressures and the low experience with these pumping systems, it is important to consolidate the hydraulic model used in the design. The loop test setup in this case was used to support the selected hydraulic model. Based on data from a loop test set up at a Brazilian mining company located in the Iron Quadrangle (Quadrilátero Ferrífero), the study proposes to validate the Hanks & Dadia (1971) model using yield stress correction according to the Buckingham equation presented by Abulnaga (2002). In the loop test, the fine iron ore tailings were pumped using positive displacement pumps. The viscosity of the tailings varied between 0.013 and 0.017 Pa.s and the yield stress between 31 and 42 Pa. Very close results were observed between the actual data from the loop test and the head loss calculation by the Hanks & Dadia (1971) model using the yield stress correction, according to the Buckingham equation.