PREDICTING ACID ROCK DRAINAGE FROM A NICKEL MINE WASTE PILE AND METAL LEVELS IN SURROUNDING SOILS

2017 ◽  
Vol 16 (9) ◽  
pp. 2089-2096
Author(s):  
Artwell Kanda ◽  
George Nyamadzawo ◽  
Jephita Gotosa ◽  
Nathan Nyamutora ◽  
Willis Gwenzi
Keyword(s):  
Acid Rock Drainage ◽  
Mine Waste ◽  
Acid Rock ◽  
Metal Levels

Field experimental cells to assess hydrogeological behaviour of store-and-release covers made with phosphate mine waste

2015 ◽  
Vol 52 (9) ◽  
pp. 1255-1269 ◽  
Author(s):  
Bruno Bossé ◽  
Bruno Bussière ◽  
Rachid Hakkou ◽  
Abdelkabir Maqsoud ◽  
Mostafa Benzaazoua
Keyword(s):  
Acid Rock Drainage ◽  
Mine Waste ◽  
Matric Suction ◽  
Water Infiltration ◽  
Mine Wastes ◽  
Acid Rock ◽  
Release Capacity ◽  
Cover Systems ◽  
Phosphate Mine ◽  
Hydrogeological Behaviour

A field investigation was conducted to evaluate the effectiveness of store-and-release (SR) covers made with different phosphate mine wastes in reducing water infiltration (system inclination and surface runoff were neglected) and controlling acid rock drainage (ARD) generation. Four instrumented experimental cells were constructed with different SR layer configurations (two thicknesses and three materials) placed over a capillary break layer. To assess the hydrogeological behaviour of these cover systems, volumetric water content, matric suction, and meteorological monitoring time trends were studied for a period of 1.5 years under actual and extreme conditions typical of an arid climate. Under natural climatic conditions, all net infiltration was released to the atmosphere by the physical process of evaporation (regardless of SR layer thickness and type). Although high surface matric suction (>3000 kPa) decreased the evaporation rate (or release capacity) during the drying period, field tests showed that the studied scenarios limited deep water infiltration even under extreme rainfall events. The release capacity of the SR layer was slightly lower for cover systems made with the finer-grained mine waste (phosphate limestone tailings). This study showed that, for a one-dimensional (1D) condition, the tested phosphate mine wastes have the appropriate hydrogeological properties to be used as components of SR covers under conditions at the Kettara mine site, located near Marrakech, Morocco.

Mechanical response of highly gap-graded mixtures of waste rock and tailings. Part I: Monotonic shear response

2010 ◽  
Vol 47 (5) ◽  
pp. 552-565 ◽  
Author(s):  
Ali Khalili ◽  
Dharma Wijewickreme ◽  
G. Ward Wilson
Keyword(s):  
Management Practices ◽  
Mechanical Response ◽  
Acid Rock Drainage ◽  
Mine Waste ◽  
Shear Loading ◽  
Waste Rock ◽  
Traditional Methods ◽  
Acid Rock ◽  
Shear Response ◽  
Rock Particle

The idea of mixing mine tailings and waste rock to form “paste rock” prior to disposal is now receiving significant attention from the point of view of sustainable mine waste management practices. This approach has been viewed as a favourable alternative to traditional methods of mine waste disposal because paste rock has the potential to overcome deficiencies (e.g., acid rock drainage and liquefaction-induced failures) associated with traditional methods. To advance the current limited knowledge, a laboratory research program was undertaken to study the mechanical response of paste rock. Testing was undertaken on paste rock specimens prepared so that the tailings would “just fill” the void spaces within the waste rock particle skeleton. The findings suggest that the material is unlikely to experience flow deformation under monotonic shear loading conditions, at least up to the tested initial effective confining stress conditions of 400 kPa. The monotonic shear response of paste rock was found to be similar to that of rock-only material; this finding is in agreement with previous observations from one-dimensional consolidation testing where it had been shown that the rock particle skeleton would carry almost 90% of the externally applied stress on a given paste rock mass.

scholarly journals Acid Rock Drainage or Not—Oxidative vs. Reductive Biofilms—A Microbial Question

2018 ◽  
Author(s):  
Margarete Maria Kalin ◽  
Soeren Bellenberg ◽  
William Nielson Wheeler
Keyword(s):  
Acid Rock Drainage ◽  
Mine Waste ◽  
New Technology ◽  
Field Tests ◽  
Inhibitory Effect ◽  
Organic Coating ◽  
Coal Waste ◽  
Mineral Surface ◽  
Acid Rock ◽  
Sulphide Oxidation

Abstract: Measures to counteract AMD generation need to start at the mineral surface, inhibiting mineral-oxidizing, acidophilic microbes. Laboratory and long-term field tests with pyrite-containing mining wastes, where Carbonaceous Phosphate Mining Waste (CPMW) was added, resulted in low acidity, and near neutral drainage. The effect was reproducible, nd confirmed by several independent research groups. This was shown to involve an organic coating, likely a biofilm. The biofilm formation was confirmed when CPMW was added to lignite coal waste with an initial pH of 1. Forty five days after the addition, the coal waste was dominated by heterotrophic microorganisms in biofilms. A review of the scientific literature supports that CPMW has physical and chemical characteristics which are capable of inducing a strong inhibitory effect on sulphide oxidation by forming an organic coating over the mineral surface. CPMW characteristics appear to provide the cornerstone of a new technology for the reduction of sulphide oxidation in mine wastes. An hypothesis for testing this technology is presented which could result in an economical and sustainable approach to mine waste and water management.

Design and evaluation of mixtures of mine waste rock and tailings

2006 ◽  
Vol 43 (9) ◽  
pp. 928-945 ◽  
Author(s):  
Benjamin E Wickland ◽  
G Ward Wilson ◽  
Dharma Wijewickreme ◽  
Bern Klein
Keyword(s):  
Acid Rock Drainage ◽  
Mine Waste ◽  
Mixture Design ◽  
Particle Packing ◽  
Waste Rock ◽  
Particle Model ◽  
Acid Rock ◽  
Mixture Ratio ◽  
Mine Waste Rock ◽  
Laboratory Investigations

The technique of mixing mine waste rock and tailings for disposal has the potential to avoid the problems of acid rock drainage and tailings liquefaction. This paper presents a rational basis for the design of mixtures based on particle packing theory and laboratory investigations. Mixtures were conceptualized using a particle model that allows mixture design and interpretation of behaviour. Laboratory investigations included examination of tailings rheology, mixture trials, and compressibility testing of waste rock, tailings, and mixtures of waste rock and tailings. Results indicate that mixture design governs mixture structure, and consequently also compressibility behaviour. A method is presented to predict mixture compressibility from mixture ratio and the properties of the parent waste rock and tailings. The study provides theory for the design and evaluation of mixtures as a mine waste disposal technique and demonstrates that the design of geotechnical properties is possible for homogeneous mixtures of mine wastes at the laboratory scale.Key words: co-disposal, particle packing, rheology, compressibility, waste rock, tailings.

Variations in moisture content for a soil cover over a 10 year period

2005 ◽  
Vol 42 (6) ◽  
pp. 1615-1630 ◽  
Author(s):  
Björn Weeks ◽  
G Ward Wilson
Keyword(s):  
Moisture Content ◽  
Soil Cover ◽  
Acid Rock Drainage ◽  
Lower Layer ◽  
Mine Waste ◽  
Waste Rock ◽  
Weather Data ◽  
Moisture Profile ◽  
Acid Rock ◽  
Cover Design

The Equity Silver mine is located in north-central British Columbia and is the site of a large, well-instrumented soil cover. The soil-cover site was designed to prevent the generation of acid rock drainage from the acid-generating waste rock disposed of at this site. The cover was designed to act as an oxygen barrier by maintaining a layer of saturated soil above the waste rock. The cover consists of a compacted till placed over the waste rock and covered with a non-compacted layer of the same material. Neutron probes and thermal conductivity sensors were used to monitor the moisture content of the cover soil over a 10 year period. Weather data at the site were also collected. A review of the data collected has shown that saturation was maintained in the lower, 0.5 m thick compacted layer of the cover, as per the original cover design. The upper cover layer (0.3 m of noncompacted till) was subject to seasonal variations in moisture content, with drying in the summer months and wetting in the fall and spring. Variations in the moisture of the upper layer correlated well with the weather data collected at the site. Spatial variations were noted in the water contents measured over the cover, but a nearly saturated lower layer appears to have been maintained throughout the area monitored.Key words: soil cover, neutron probes, moisture profile, mine waste covers.

Hydraulic conductivity and consolidation response of mixtures of mine waste rock and tailings

2010 ◽  
Vol 47 (4) ◽  
pp. 472-485 ◽  
Author(s):  
Benjamin E. Wickland ◽  
G. Ward Wilson ◽  
Dharma Wijewickreme
Keyword(s):  
Hydraulic Conductivity ◽  
Acid Rock Drainage ◽  
Mine Waste ◽  
Waste Rock ◽  
Column Studies ◽  
Acid Rock ◽  
One Dimensional ◽  
Specimen Diameter ◽  
Dense Deposits ◽  
Mine Waste Rock

Hydraulic conductivity and consolidation behaviour are examined for an alternative mine waste disposal technique. One type of waste rock, one type of tailings, and mixtures of the same waste rock and tailings were tested in bench-scale and column studies. Specimens 150 mm in diameter were tested for hydraulic conductivity by falling-head method alternated with one-dimensional consolidation, specimens 300 mm in diameter were tested for one-dimensional consolidation response, and specimens 1 m in diameter were tested for self-weight consolidation behaviour in 6 m high columns. Deformation of mixtures under one-dimensional loading was similar to that of waste rock alone and much less than that of tailings alone. Hydraulic conductivity of mixtures was similar to that of tailings alone and independent of specimen diameter. Mixture behaviour was attributed to a homogeneous structure including waste rock in particle-to-particle contact and a continuous, saturated matrix of tailings. The results indicate that mixing waste rock and tailings can produce dense deposits with values of hydraulic conductivity that are orders of magnitude lower than those of waste rock alone, thereby limiting fluxes through the waste and the associated potential for acid rock drainage. Mixture deposits will also have less consolidation-related settlement than tailings, thus improving stability and aiding reclamation.

Mathematical modeling for optimized mine waste rock disposal: Establishing more effective acid rock drainage management

2020 ◽  
pp. 125124
Author(s):  
Vahid Vaziri ◽  
Ahmad Reza Sayadi ◽  
Amin Mousavi ◽  
Anita Parbhakar-Fox ◽  
Masoud Monjezi
Keyword(s):  
Mathematical Modeling ◽  
Acid Rock Drainage ◽  
Mine Waste ◽  
Waste Rock ◽  
Acid Rock ◽  
Mine Waste Rock

Design of a composite soil cover for an experimental waste rock pile near Newcastle, New Brunswick, Canada

1993 ◽  
Vol 30 (4) ◽  
pp. 578-587 ◽  
Author(s):  
Ernest K. Yanful ◽  
Alan V. Bell ◽  
Mark R. Woyshner
Keyword(s):  
New Brunswick ◽  
Soil Cover ◽  
Acid Rock Drainage ◽  
Mine Waste ◽  
Gas Diffusion ◽  
Climatic Conditions ◽  
Waste Rock ◽  
Freezing And Thawing ◽  
Gaseous Oxygen ◽  
Acid Rock

The Heath Steele Waste Rock Project was initiated in 1989 under Canada's Mine Environment Neutral Drainage (MEND) Program to develop and test strategies for managing acid-generating waste rock. The multiphase project involved the identification and selection of a few waste rock piles for field evaluation at the Heath Steele mine site located at about 50 km northeast of Newcastle, New Brunswick. As part of the evaluation, a 0.25-ha acid-generating pile, pile 7/12, was relocated and reconstructed on an impermeable synthetic membrane by end dumping from the perimeter and pushing into the middle section. The pile, which contains about 14 000 t of mine waste rock, has been producing an acidic seepage characterized by high dissolved iron (3.5–13.5 g/L) and sulphate (12.7–43.4 g/L) concentrations. Following the definition of the baseline acid-generating characteristics of the pile and laboratory investigation of potential soil cover materials in the vicinity of the site, a three-layer cover design is proposed. The design calls for a 60 cm thick saturated impermeable cover sandwiched between a 30 cm thick sand base and a 30 cm thick, overlying granular layer. The principal objectives of the design are to obtain a low gas diffusion coefficient to minimize oxygen fluxes and, also, to attain a low hydraulic conductivity to reduce infiltration into the pile. Both objectives can be achieved by compacting the impermeable cover at a density of 95% of Modified Proctor or greater and a water content slightly higher than the optimum value. The design of the cover and the anticipated resulting low gaseous-oxygen fluxes are confirmed by one-dimensional diffusion modelling. The potential for the impermeable layer to remain nearly fully saturated, even under an evaporative flux, is demonstrated by flow modelling. It is noted that the assessment of the durability of the cover with respect to variable climatic conditions (drying, freezing, and thawing) is a critical component of the performance evaluation. Key words : acid rock drainage, soil cover, capillary barrier, oxygen flux, infiltration.

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