Search Documents

By Ben E. Adams

The Duval Corporation Sierrita copper and molybdenum mining complex is located approximately twenty-three miles south of Tucson, Arizona. The original open pit mine, Esperanza, was put into operation in 1958 and utilized one tailings dam until the Sierrita operation began in 1970, and a second pond was started. Both tailings operations continued to be operated separate and independently of each other until 1977, when the Esperanza Mill was temporarily shut down, and the Esperanza Tailings Dam was retired from service. Except for short periods of use, no new tailings were put on the surface. With the reactivation of the Esperanza Mill in 1979, the Esperanza tailings were combined with the Sierrita Mill tailings and put on the Sierrita Dam, leaving the Esperanza Dam in a retired state.

Jan 1, 1984

By T. P. Lim, J. A. Cherry, A. J. Vivyurka, R. D. Blair

The first phase of an investigation of the chemical composition of subsurface water and the hydrochemical processes in and near the abandoned Nordic tailings at Elliot Lake, Ontario, was conducted in 1979. The Nordic area, which covers 85 hectares with an average thickness of 10 m and overlies deposits of permeable glaciofluvial sand, contains 15 million tonnes of tailings with 4-7% pyrite. Nests of standpipe piezometers installed at three locations on the tailings indicate that seepage through the tailings is predominantly downward. The water table in the tailings slopes from the north side of the tailings dam, where it is within a metre of surface to the south side near the tailings dam, where it is approximately 10 m below surface. When they were deposited during the period from 1957 to 1968, the tailings contained pore water at a pH of about 8 resulting from neutralization treatment in the mill. At the three piezometer nests, the pH increases from 3 near the water table to 7 near the bottom of the tailings. The pore water in the tailings is gradually becoming acidic because of oxidation of pyrite in the zone above the water table. The concentrations of Fe, Mn, Ni, Co, Zn and Pb are high in the shallow acidic zone and much lower in the deeper neutral zone. Concentrations of 226Ra range from 30 to 230 pCi/L. At the three sites concentrations of major ions in the permeable sand a short interval beneath the tailings indicate 226Ra presence of tailings seepage, but Ra concentrations are only 2 to 8 pCi/L. Greater downward penetration of 226Ra probably occurs in the area closer to the tailings dam. Monitoring of a network of multilevel bundle piezometers installed in permeable sand that extends southward from beneath the tailings indicates the occurrence of a plume of tailingsderived water containing high concentrations of Ca, Mg, Fe and S04 that extend 400 m downgradient from the tailings dam. The total dissolved solids decline from 20,000 at the dam to less than 500 mg/L at the identifiable downgradient periphery of the plume. A much smaller but distinct plume of water with high heavy metal concentrations and 226Ra in the range of 10 to 130 pCi/L extends from beneath the dam for a distance of 15 m. The pH of the groundwater in this heavy metal-radium plume is 4 to 5, whereas elsewhere in zone of groundwater with high dissolved solids, the pH is above 6. The results of this investigat, suggest that the heavy metals an 226 Ra are relatively immobile in the perme-

Jan 1, 1980

By D J. A Van Zyl, J C. Cunning

Technological advances associated with the expanded application of paste technology in underground mine backfilling are now stimulating an interest in the disposal of process tailings as paste in the surface environment. Concurrent with the development of alternative surface tailings disposal practices is the requirement to fully understand the consolidation behaviour of tailings in paste form, and to relate this understanding to the significant body of data and operating experience from decades of study of the performance of hydraulically placed tailings. One effective method for demonstrating the benefits derived from handling and placement of tailings as paste is to review tailings slurry consolidation theory from the perspective of the changes which take place in the material as it makes its transition from a loose slurry to a dense, stable deposit resulting from managed thin-layer deposition. For a typical process tailings, an example is provided which illustrates the effect which mechanical dewatering has in accelerating the consolidation process and thereby providing a range of benefits from the perspective of surface disposal. Increased rates of filling (rise), expanded use of upstream embankment construction methods and elimination of impounded surface solutions are some quantifiable benefits which can be assembled on a site-specific basis to allow for valid comparisons with more traditional approaches to tailings disposal.

Jan 1, 1998

By N Currey, G W. Wilson, P Ritchie

Kidston Gold Mine in Queensland, Australia has a 310 ha tailings impoundment that has undergone final closure rehabilitation. Kidston Gold Mine evaluated their closure options for this low acid generating tailings impoundment, and due to a lack of cover soils and the cost of importing material, the mine decided to investigate the possibility of direct vegetation onto the tailings impoundment surface. The mine subsequently embarked upon a well planned and detailed research program to determine the feasibility and sustainability of this closure option. The research program included vegetation trials, toxicology studies for metal uptake by vegetation, as well as a comprehensive closure water balance model for the tailings impoundment complex. This paper describes the results of the long-term closure water balance for the tailings impoundment complex for the pre-closure state of the impoundment, as well as predictions towards the impoundment performance once final rehabilitation of the tailings impoundment complex has been achieved. The water balance presented is unique in that it is founded on unsaturated flow principles and accounts in full the impacts of the surface flux boundary conditions. This novel approach enables the prediction of actual infiltration rates into the tailings impoundment surface, which in turn allows for the calculation of how much seepage will exit from the tailings dam toe drains.

Jan 1, 2003

By R. D. Doepker, P. L. Drake

The dissolution of metals from various metal- mine tailings has been studied through a series of submerged tailings batch tests at US Bureau of Mines laboratories. Tailings selected for this study included both reactive (as determined by column leaching studies) and benign tailings. Metal mobilization in aerated (97% saturated with oxygen) samples appeared to be consistently greater than metal dissolution from stagnant (79% or 70% saturated with oxygen) waters. In the early weeks of the study, sulfate concentrations increased with solid-liquid contact time, while calcium dissolution remained early constant. Metal concentrations varied in relation to solid-liquid contact time and aeration. Leachate pH appeared to be nearly independent of solid-liquid contact time for basic tailings. Reactive tailings having both a submerged and a surface component demonstrated increased metal mobility.

Jan 1, 1991

By Tracy Shimmield

Deep sea tailings placement (DSTP) techniques have been pioneered in Papua New Guinea (PNG): a mining reliant economy in a seismically active region, facing major environmental challenges in the safe handling and storage of mine tailings on land. Scientists at SAMS have researched impacts of DSTP on the marine environment specifically to inform and develop guidelines for the use of DSTP to reduce environmental impact, thereby lowering risk and increasing private sector investment. Guidelines have been established as regulation by the PNG Government providing reassurance to private investors, facilitating an increase in mining exports to 60% of total export. Researchers investigated the effects of DSTP at 2 PNG mines: Lihir Gold Mine which has been actively discharging tailings since 1996 and Misima Mine, closed in 2004 after discharging tailings for 15 years, allowing an assessment of the recovery of the marine environment after tailings placement. Research involved investigating ocean currents and mixing, the behaviour of metals and the effect of tailings on benthic communities including the risk of elevated metal contents entering the food chain. The research established a metal ?fingerprint? of tailings compared to natural sediments, which enabled the transport of fine tailings within the deep ocean to be ascertained.

Sep 14, 2011

By K. A. Hughes

Under the oxidizing conditions of the McClean Lake Tailings Management Facility (TMF) hydrocarbons entrained on the surface of tailings material from mill processes are gradually converted to soluble bicarbonate ion. This has been observed to be a process occurring over approximately three years likely encouraged by the presence of a microbiological community within the tailings mass and in the water column. A recent tailings sampling campaign has provided evidence that bicarbonate ion is participating in the conversion of gypsum to calcite. In older tailings, equilibrium with calcite appears to be controlling the terminal bicarbonate ion concentration.

Aug 1, 2010

By W. G. Miller, J. D. Scott, D. C. Sego

ABSTRACT The influence of using different extraction processes (caustic versus non-caustic) on thethixotropic strength of oil sands fine tailings is examined, as is the influence of adding a coagulant tocaustic fine tailings. The thixotropic strength of fine tailings at large void ratios manifests itself as a bonding or gel strength that has been widely noted both in the laboratory and in the field. This gel strength has a significant influence on preventing the initial consolidation or settlement of fine tailings. Differences between the fine tailings’ thixotropic strength development are explained based on their physical and chemical characteristics.

Jan 1, 2010

By Wu Aixiang, Zhou Qian, Zhou Zaibo, Liu Juanhong, Wang Hongjiang

To improve the pumping capacity and engineering efficiency of fresh thickened tailings slurry, a high charge density superplasticizer was developed to improve the rheological properties of tailings slurry. The effects of superplasticizer content, the concentration and fineness of tailings, the proportion and type of cementitious materials, temperature, and hydration time on the rheological properties of unclassified tailings slurry and backfill materials were studied. The variation characteristics of the slurry yield stress, plastic viscosity, and thixotropy with different factors were measured by a Brookfield R/S-SST plus rheometer. The experimental results of fresh thickened tailings illustrated that the higher the concentration of the slurry and the finer the tailings, the worse the rheological properties of the slurry. The results of cemented paste backfill materials indicated that the rheological parameters increased as binder content and time increased. The rheological parameters decreased as the temperature increased. The addition of a superplasticizer reduced the rheological parameters and improved the rheological behavior of the fresh thickened tailings and cemented paste backfill materials, which was beneficial to the slurry’s pipeline transportation. This paper can provide technical guidance for slurry transportation in the backfill system and provide a reference for designing the superplasticizer used in tailings.

Jan 5, 2022

By J. Locat, G. Parker, D. Turmel

ABSTRACT Since 1964, the Iron Ore Company of Canada has deposited iron ore tailings into Wabush Lake in western Labrador, Canada. From 1999 to 2008, the authors completed multibeam bathymetric and sampling surveys and an airborne LiDAR survey. These data were integrated to study the evolution of the tailings delta shoreline and lakebed elevation. Subaqueous channels evolved between surveys, influencing the tailings depositional pattern. With this analysis it is possible to evaluate the effect of disposal strategies on the delta topset and tailings accumulation. This project uniquely couples marine and terrestrial techniques to follow the fate of tailings in a dispersal system.

Jan 1, 2014

By Jérôme Girard, Shiu Kam, Sue Longo

"Historically, tailings management in a northern climate has involved the deposition of tailings into the Tailings Management Area (TMA) as conventional slurry. This type of system is obviously viable but presents challenges that are difficult to manage as circumstances change over the life of mine. These issues can include:? Increases in mill throughput, and? Life of the TMA for the life of mine.This case study will present how thickened, high-density, non-segregating tailings are used as an alternative to conventional slurry disposal to achieve greater storage capacity and enhanced environmental performance for a gold tailings facility in a northern climate. This paper will focus on how this change in deposition strategy accommodated the increased throughput of the mill and the increased life of mine. Specifically, the paper will discuss the addition and integration of new processes to the exiting mill system to accommodate the tailings management issues. It will highlight the challenges from laboratory testing to pre-feasibility to the engineered design of the thickened tailings system implemented at Musselwhite Mine.BACKGROUNDGoldcorp Canada’s Musselwhite Mine, in Northwestern Ontario (120 km north of Pickle Lake), is an underground gold mining operation that began production in 1997. The current mill throughput is about 4000 tpd (1.4 Mtpa). Gold extraction is based on a CIP process with cyanide destruction.The existing tailings management area (TMA) is located about 2 km southwest of the mill complex. The TMA is contained by high ground to the north and to the west and flanged by a moraine ridge along the south side. A number of dams have been constructed along this ridge. The dams were first built in 1996 and subsequently raised in 2000 and again in 2005. Excess tailings pond water is discharged to a polishing pond then released to the environment via a wetland.The TMA was originally designed to contain 13.7 Mt of tailings under a ponded surface for closure. The water cover was to inhibit adverse long-term environmental effects because the tailings contain pyrrhotite and other sulphide-bearing minerals that are potentially acid generating. The design was modified during Stage 3 Construction in 2005 to expand the storage capacity to 17.3 Mt (Golder, 2005). As of end of 2009, over 16 Mt of tailings had been deposited in the TMA. The slurried tailings were historically deposited at 50% solids."

Jan 1, 2011

By Kevin Schraden, Andrea Pezzi

environmental and social/political changes the world is currently experiencing. Three of major challenges facing the mining industry today are: water scarcity, unpredictable weather conditions that generate a risk of tailings dam failures as well as the correlating social pressure and government regulations that prevent the development of new or expanded tailings dam projects. It is estimated the total number of active, inactive and closed storage facilities globally is over 8,500 containing over 217 km3 of tailings (46% are from copper mining)1 which at some point will need to be addressed. Technologically, there are several solutions for tailings management, including conventional ponds, thickened tails, paste backfill and filtered dry stack tailings. The use of pressure filters, for tailings dewatering is currently being evaluated and often selected as the preferred technology where dry stacking is the chosen solution for residue disposal. This is mainly due to the pressure filters ability and flexibility to address and achieve the current challenging aspects of tailings processing including: • Extremely high capacities of >80,000 dry tons/day • Lower ore grades which require finer grinding and result in a higher amount fine fractions and clay content • Residual moisture targets required for the geotechnical specifications for dry stacking

Feb 1, 2024

By N Kawashima, R St C Smart, A M. Robertson

This paper focuses on a case study at a base metal mine located in a tropical semi-arid area of Western Australia (WA). It is demonstrated that understanding the geochemical nature of the mine tailings forms an integral part of innovative management strategies developed throughout the life-of-mine (LOM) when planning for mine closure. The tailings are currently stored at an above-ground valley fill tailings storage facility (TSF) and one option for long-term management under consideration is leaving the tailings in situ at mine closure and covering using the concept of an enhanced æstore and releaseÆ cover system.Extensive geochemical and mineralogical studies have found that the geochemical behaviour of the tailings in the TSF is significantly more benign than initially predicted. The sulfide content of the tailings is primarily pyrrhotite, which can be acid-forming, acid-neutral or acid-consuming depending on a number of factors including redox conditions. Tailings pore water at depth is pH neutral with excess alkalinity, low concentrations of dissolved metals and elevated sulfate concentration.Recent geochemical tests on tailings samples indicate that a reduction in the acid potential and a corresponding increase in the neutralising potential of the tailings, through partial removal of pyrrhotite at the ore processing stage, has the potential to further reduce the long-term risk of potential impact to the environment from any TSF seepage. The current work program investigates whether partial removal of pyrrhotite is feasible and secondly, whether this approach is necessary to produce a significantly better outcome at mine closure.CITATION:Robertson, A M, Kawashima, N, Smart, R St C and Schumann, R, 2012. Understanding tailings geochemistry - Continuous learning and innovation when planning for mine closure, in Proceedings Life-of-Mine 2012 , pp 287-292 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By Paktunc. A. Dogan, Nand K. Davé

Unsegregated pyritic uranium mill tailings from Elliot Lake, Ontario, with and without limestone amendment, were subjected to column leaching experiments for the purposes of predicting the onset of acidic drainage and the magnitude of metal and radionuclide release under various treatment and control strategies. The unamended tailings produced acidic drainage after approximately one and a half year. The tailings mixed with various grain-sized limestone did not produce acidic drainage during the study period. The tailings consist essentially of quartz, K-feldspar, muscovite and pyrite. The unsegregated tailings amended with very fine limestone displayed the least amounts of pyrite loss whereas those without limestone amendment had the greatest pyrite losses. Predicted onset of acid generation varied from 16 to 75 years for the top sections and in most cases greater than 100 years for bottom sections of the unsegregated tailings with limestone amendments. Unsegregated tailings mixed with fine- and very fine-grained limestone proved to be the most effective in controlling or delaying the onset of acidic drainage under unsaturated conditions.

Jan 1, 2000

By P E. H Gregg, R B. Stewart

Reclamation field trials commenced in 1985, two years before the granting of the Mining Licence. The level of pasture production on varying soil depths (0 cm, 5 cm, 15 cm and 25 cm) overlying both tailings and oxidised waste overburden was assessed.   After seven years, the rate of increase of N, C, P and S, losses of Sand P and pH changes were investigated on the plots where grass seed was sown into bare tailings. It was determined that on these plots it would take approximately 24 years to reach the original carbon and nitrogen levels at the mine site. Further tailings trials have been initiated to investigate alternative land use options for the tailings dam. Growth increases of 73% occurred in native species growing directly in tailings, and growth increases of 78% occurred in tailings amended with compost over the first six months. Pasture trials on tailings with and without a compost amendment have also been initiated. Research has commenced to investigate the restoration options for acid producing pit slopes. The early field trials have been put into practice with the restoration of oxidised waste on the tailings embankment. This is progressive with approximately 16 ha restored to productive pasture at present. Yields compare well with those of the most versatile and productive soils types investigated in baseline studies of the area before the tailings dam was constructed.

Jan 1, 1995

By G Burton, S Fityus, J Li, S Vaughan, D Payne

Daunia and Caval Ridge coal mines, owned and operated by BHP, have been co-disposing rejects and dewatered tailings within spoil dumps from the beginning of their operations in 2013 and 2014, with the purpose of minimising environmental impact and geotechnical risk. Following the recent large failures of tailings dams around the world, BHP Coal, through its Coal Tailings Program, plans to transition other coal mines to deliver “dry” tailings and produce mixed plant rejects (MPR) for inpit co-disposal. This will materially reduce future tailings dam risk exposure. Previous laboratory shear strength testing was conducted on rejects with a maximum particles size of 20 mm, and some concerns were raised that this might not represent the mechanical properties of the actual full particle size distribution (PSD) rejects. BHP was also aware that using different technologies to dewater the tailings, such as belt press filters (BPF) and solid bowl centrifuge (SBC), could produce thickened tailings which could significantly modify the physical behaviours of the MPRs, particularly the bonding between particles. Therefore, laboratory testing on both coarse rejects and mixtures of the coarse rejects and dewatered tailings (MPRs), with full PSDs, was carried out. Testing was performed using the large direct shear machine developed by the Australian Coal Association Research Program (ACARP) project C20019 in 2017, as well as a 300 mm diameter triaxial apparatus at the University of Newcastle (UoN). This paper presents details of the laboratory testing program and results for the rejects from the first studied mine of the BHP Coal Tailings Program. It compares the shear strengths measured at full scale with those tested on modified (scalped or crushed) specimens in the past; and discusses the tailings dewatering technique selection from geotechnical aspects based on the testing results, and finally presents some dump and tip head stability analysis results using the testing results.

Jul 1, 2021

By D. Murray

A 2-hectare uranium tailings area has been reclaimed. The exposed tailings of 1.4 hectares were capped with glacial till and vegetated with grasses and legumes. The water running through the tailings was diverted around the tailings in a line ditch and treated with sodium hydroxide and barium chloride. Difficulties occurred in placing the till capping because of the low bearing strength and the uneven surface of the tailings. This led to varying thicknesses of till and the need for manual labour in some areas. Total reclamation costs were $32,200, with vegetation establishment costs at $13,700 per hectare. This report provides a record of work for use in assessing the long-term suitability of these treatments.

Jan 1, 1979

By R. D. Doepker

The dissolution of metals from various metal-mine tailings has been studied through a series of submerged tailings batch tests at U.S. Bureau of Mines laboratories. Tailings selected for this study included both reactive (as determined by column leaching studies) and benign tailings. Metal mobilization in aerated (97 pct saturated with oxygen) samples appeared to be consistently greater than metal dissolution from stagnant (79 pct or 70 pct saturated with oxygen) waters. In the early weeks of the study, sulfate concentrations increased with solid-liquid contact time, while calcium dissolution remained nearly constant. Metal concentrations varied in relation to solid-liquid contact time and aeration. Leachate pH appeared to be nearly independent of solid-liquid contact time for basic tailings. Reactive tailings having both a submerged and a surface component demonstrated increased metal mobility.

Jan 1, 1990

By G Johnson, G W. Wilson

The settlement and drainage behaviour of co-mix, or mixtures of waste rock and tailings, are examined in a column study. Three co-mix profiles were observed for settlement, drainage, and pore water pressure response. A fourth profile with waste rock and no tailings was also observed for settlement. Co-mix consolidated faster than predictions for tailings alone, and maintained a saturated void space relative to waste rock alone. Practical benefits of co-mix as a waste disposal technology may include faster time to consolidation than tailings, a reduction in total settlement of placed material compared to tailings alone, and a reduction in acid drainage by limiting the flow of water and oxygen through maintenance of a saturated void space.

Jan 1, 2003

By Rick J. Chalaturnyk

In Alberta, oil sands bitumen is utilized for synthetic crude oil production by surface mining, bitumen extraction followed by primary (coking) and secondary (catalytic hydrotreating) upgrading processes, or by catalytic hydrocracking and hydrotreating replacing the primary and secondary upgrading processes. Oil sands tailings, composed of water, sands, silt, clay and residual bitumen, is produced as a byproduct of the bitumen extraction process. Several processes have been proposed for the treatment of oil sands tailings, resulting in different recovered water characteristics, consolidation rates and consolidated solid characteristics, which may have effects on the performance of the overall plant operations. A process for the same purpose has been developed by treating the oil sands tailings with CaO lime and CO2 and thickening it using a suitable thickener. In this process a release water of acceptable properties is recovered in a short retention time, which makes it possible to recycle the recovered water, probably after a reconditioning treatment, as warm as possible to improve the thermal efficiency of the extraction process. The paper presents the theory and laboratory results for the CaO and CO2 thickening of low temperature flotation tailings. The water release rates, segregation potential of the thickened underflow and chemistry of the release water are shown and discussed. It is suggested that in using the proposed process, the thickened tailings underflow can be disposed for further consolidation, or combined with the coarse tailings to produce Blended Composite Tailings, corresponding to the Composite Tailings process in the existing hot water extraction plants.

May 1, 2002