?To explore the spatial strength distribution of backfill in the stope, a group of experiments in a large similar stope model was designed for simulating the consolidation of cemented tailings backfill (CTB) in a stope. The height of CTB in similar stope model was measured to analyse the flow and sedimentation characteristics. The unconfined compressive strength (UCS) test on specimens cored in the different position of CTB sample in similar stope model was conducted. Moreover, the particle size and cement content of CTB sample were tested to help to explain the mechanism. The results show that during the flow and sedimentation of filling slurry in the model, inconsistency of the particle size and cement content leads to the inconsistency of strength. In the flow direction (horizontal direction), the median particle size of CTB first increases and then decreases, the cement content of CTB decreases slowly and then increases sharply, and the strength of CTB first decreases and then rises. In the sedimentation direction (vertical direction), the cement content of CTB decreases with the increase of depth, while the strength of CTB increases with the increase of depth. The strength is affected by the interaction between particle size and cement content, and the higher cement content of CTB does not translate into higher strength. The results provide a theoretical basis for improving the quality of CTB and optimizing the design.
?There has been an increasing move towards high-density thickened tailings systems over the last decade, mainly driven by the need to save water, meet environmental regulations and project specific demands. A typical tailings distribution system on a Tailings Storage Facility (TSF) consists of a main pipe with multiple discharges operating simultaneously, to distribute the slurry across an extended length over a specific area of the TSF at a time. A potential limitation of these systems is an uneven distribution of slurry flow rate and solids concentration between multiple spigot discharges, where an inadequate design can lead to laminar pipeline flow conditions resulting in particle segregation, and an increased risk of pipeline blockage. An operation with unbalanced flow rates could result in an uneven distribution of solids that could impact the formation of beach slopes and/or cause difficulties for the dam construction. Paterson & Cooke (P&C) has previously developed several thickened tailings distributed systems, where the discharge points are located on a distribution pipeline which branch off a main pipeline. This previous experience has allowed P&C to develop a methodology for the hydraulic modelling and implementation of these types of systems. This paper presents the methodology for distribution system deposition design review and its implementation of a TSF located in Southern Europe.
Given the current scenario experienced by Brazilian mining industry, the study and development of technologies that enable a more secure and controlled disposal of tailings has gained significant relevance. Among the various alternatives and disposal methodologies, Anglo American has been developing tests on different study fronts. Using dewatering polymers to improve tailings store potentials at tailings dam is one of the methods that has been studied extensively. The tested polymers can enhance de-watering performance and immobilization of mineral slurries during hydraulic deposition, therefore achieving optimization of tailings storage at the existing facility. The studies were divided into laboratory and industrial field-testing phases aiming to evaluate the applicability of this technology for eventual implementation at industrial scale. During the laboratory testing phase, more than two hundred tests were performed to determine the best polymer type, dilution and dosage. The parameters evaluated were based on yield stress measurements by a rheometer, slump tests performance and water released volume after 10 minutes and 24 hours after polymer addition. The results from laboratory testing phase have provided sufficient information for industrial scale trial. The second phase of the study consisted of an industrial field trial with polymer application in the tailings dam for five days. During the trial, topographic measurements were taken in order to evaluate the increase of settled material during the first kilometer after tailings discharge. The results demonstrated a significant increase of settled material and beach slope angle in the measured area. This showed a good potential for improved utilization of the storage in the tailings storage facility in the coming years.
Decision Support System for Water Infrastructure Security Human Consequence Module (DSS-WISETM HCOM) is an analytical module for automated assessment of the human consequences of dam-break floods. The National Center for Computational Hydroscience and Engineering (NCCHE) and the University of Mississippi developed the module with funding provided by the U.S. Federal Emergency Management Agency (FEMA) through a contract with Argonne National Laboratory.
DSS-WISE Lite is a web-based, automated two-dimensional dam-break flood modeling and mapping capability developed by the National Center for Computational Hydroscience and Engineering (NCCHE), the University of Mississippi. The development of the web-based tool and its operation and maintenance is supported by the U.S. Federal Emergency Management Agency (FEMA).
Secure, web-based graphical user interface and map server providing analytical capabilities and a decision support system for dam/levee security.
Manual summarizing the methodologies used by the bureau to perform flood hydrology studies.
Evaluation of highly thickened tailings technologies requires that during early design stages an understanding is developed for the range of feasible beach slopes to be achieved during deposition. A comprehensive evaluation of the whole range of factors that influence the beach formation process is paramount to ensure that expected performance during design stages is met throughout operations. This paper presents an integral approach for beach slope estimation, considering a broader range of aspects affecting the beach formation process than those commonly used in current models (rheology and discharge rate of the deposited tailings). The additional aspects considered by this approach are site conditions (site morphology and climate), the rate of rise of the tailings impounded (the relationship between the tailings production rate and the available area for tailings spreading) and the deposition sequence (the configuration of the deposition system and its operation, e.g. thin layer deposition with drying cycles). The approach is supported by a beach slope model based on a dimensionless parameter for non-Newtonian flows, associated with sheet flows on an inclined plane, which directly relates to the tailings beach slope expected to be formed due to sub-aerial disposal. This dimensionless parameter provides a closed expression for estimating tailings beach slopes based on rheological properties and discharge rates, but with the integration of site conditions, rate of rise and deposition sequence. High thickened tailings management facility (TMF) design is well supported by this approach, providing key input as the configuration of the distribution system and the minimum area required to achieve expected performance with respect to desired beach slope, density, degree of saturation and strength.
COSIA's Innovation Opportunities provide focused, actionable descriptions of the current state of opportunities related to environmental processes and impacts of the oil sands industry. Each represents a possibility that, if realized, would contribute towards the achievement of COSIA's environmental aspirations.
USGS Earthquake Hazards Program is responsible for monitoring, reporting, and researching earthquakes and earthquake hazards. The USGS collaborates with organizations that develop building codes (for buildings, bridges, and other structures) to make seismic design parameter values available to engineers. The design code developers first decide how USGS earthquake hazard information should be applied in design practice. Then, the USGS calculates values of seismic design parameters based on USGS hazard values and in accordance with design code procedures.