Small-scale field evaluation of geochemical blending of waste rock to mitigate acid rock drainage potential

2021 ◽  
pp. geochem2021-066
Author(s):  
S.J. Day
Keyword(s):  
Acid Rock Drainage ◽  
Field Evaluation ◽  
Waste Rock ◽  
Small Scale ◽  
Proof Of Concept ◽  
Acidic Water ◽  
Acid Rock ◽  
Acid Generation ◽  
Acidic Waters ◽  
Critical Consideration

Blending of potentially acid generating (PAG) waste rock with non-PAG waste rock to create a rock mixture which performs as non-PAG is a possible approach to permanent prevention of acid rock drainage (ARD) for PAG waste rock. In 2012, a field weathering study using 300 kg samples was implemented at Teck Coal's Quintette Project located in northeastern British Columbia, Canada to test the prevention of acid generation in the PAG waste rock by dissolved carbonate leached from overlying non-PAG waste rock and direct neutralization of acidic water from PAG waste rock by contact with non-PAG waste rock.After eight years of monitoring the experiments, the layered non-PAG on PAG barrels provided proof-of-concept that as the thickness of the PAG layer increases relative to the thickness of the non-PAG layers, acidic waters are more likely to be produced. The PAG on non-PAG layering has resulted in non-acidic water and no indications of metal leaching despite accelerated oxidation in the PAG layer shown by sulphate loadings. The study has demonstrated that the scale of heterogeneity of PAG and non-PAG materials is a critical consideration for providing certainty that rock blends designed to be non-PAG will perform as non-PAG in perpetuity. This is contrary to the standard paradigm in which an excess of acid-consuming minerals is often considered sufficient alone to ensure ARD is not produced.

Performance of engineered test covers on acid-generating waste rock at Whistle mine, Ontario

2006 ◽  
Vol 43 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Celestina Adu-Wusu ◽  
Ernest K Yanful
Keyword(s):  
Acid Rock Drainage ◽  
Geochemical Modeling ◽  
Thick Layer ◽  
Waste Rock ◽  
Test Plot ◽  
Layer System ◽  
Acid Rock ◽  
Geosynthetic Clay Liner ◽  
Clay Liner ◽  
Sandy Silt

This paper presents the design and 3 year field performance results of three engineered test soil covers for the mitigation of acid rock drainage (ARD) at Whistle mine near Capreol, Ontario. Each test cover was a two-layer system consisting of a 0.90 m noncompacted pit-run gravelly sand overlying a barrier layer. The three barrier layers studied were a 0.46 m thick mixture of sand (92%) and bentonite (8%) (SB), a 0.60 m thick layer of sandy silt with about 5% clay (SS), and a 0.008 m thick geosynthetic clay liner (GCL). Each cover was installed on 6.10 m thick acid-generating waste rock and was instrumented and monitored along with a control test plot that consisted of 6.10 m of waste rock. The ultimate objective of the study was to select a suitable cover for full-scale decommissioning of acid-generating waste rock backfilled into the Whistle pit. Results from 3 years of monitoring showed that the GCL was the most effective barrier in reducing percolation into the underlying waste rock. Percolation through the GCL barrier was 7% over the 3 year period compared with 20% and 59.6% through the sand–bentonite and sandy silt barriers, respectively, and 56.4% through the control plot. The overall quality of percolate water from the covered waste rock was much better than that of percolate water from the uncovered waste rock. Aqueous geochemical modeling suggested that percolate water draining the oxidized waste rock was controlled by hydroxides, oxide, and sulphate phases of Al, Ca, Mg, and Fe3+.Key words: waste rock, acid rock drainage (ARD), capillary barrier, geosynthetic clay liner, amended soil systems, percolation, MINTEQ.

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 Identification of the Potential of Acid Rock Drainage in the Tin Mine on Bangka Island

PROMINE ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 56-60
Author(s):  
Delita Ega Andini ◽  
Fajar Indah Puspita Sari
Keyword(s):  
Environmental Pollution ◽  
Metal Content ◽  
Acid Rock Drainage ◽  
Acidic Water ◽  
Acid Rock ◽  
Mining Areas ◽  
The World ◽  
Volcanic Processes ◽  
Granite Rocks ◽  
Potential Acidity

Bangka Belitung is one of the tin-producing areas in the world which is characterized by the large number of granite rocks in the area as the rock carrying cassiterite minerals. Granite rocks found on Bangka Island are rocks formed due to magma activity from acidic volcanic processes. The availability of acidic water is possible due to the presence of acid-carrying minerals from granite which causes acid rock drainage or acid rock water which generally occurs in mining areas, ex-mining and exploration in tin mines. Before making efforts to prevent environmental pollution, identification is needed regarding the potential acidity of the rock so that the pH and dissolved metal content that endangers survival can be prevented to a minimum.

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.

scholarly journals Assessing Environmental Risks Associated with Ultrafine Coal Wastes Using Laboratory-Scale Tests

2015 ◽  
Vol 1130 ◽  
pp. 635-639 ◽  
Author(s):  
A.K.B. Opitz ◽  
Jennifer L. Broadhurst ◽  
Susan T.L. Harrison
Keyword(s):  
Acid Rock Drainage ◽  
Laboratory Scale ◽  
Metal Species ◽  
Chemical Extraction ◽  
Supporting Evidence ◽  
Acid Rock ◽  
Static Tests ◽  
Acid Generation ◽  
Coal Wastes ◽  
Ultrafine Coal

Characterisation of the risk of acid rock drainage is typically achieved through the quantification of acid-generating and acid-consuming components present within a sample using initial laboratory-scale, chemical static tests. Such tests, however, consider ARD generation under chemical conditions and do not account for the role of micro-organisms. Their focus is exclusively on the net potential for acid generation, with no account of metal deportment or the relative rate of acid generation and consumption. The present study investigates the ARD potential of two ultrafine coal wastes samples using the standard static tests as well as the UCT biokinetic test to account for microbial ARD generation. The deportment of metal species under each test condition was also considered. The UCT biokinetic test results supported the static test classification, adding provided preliminary kinetic data on the ARD generation. Sequential chemical extraction tests allowed for differentiation of the host minerals according to their leaching potentials, providing supporting evidence for the deportment of metal species under the characterisation tests, thereby improving the knowledge base on which to classify coal wastes as benign or otherwise.

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.

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