Implications of Sulfur Speciation on the Assessment of Acid Rock Drainage Generating Potential: A Study of South African Coal Processing Wastes

The presence of sulfur in coal processing wastes can lead to environmental impacts, such as acid rock drainage (ARD). However, not all sulfur species are acid-forming, and the implications of sulfur speciation when assessing acid rock drainage potential by means of static chemical tests are not well understood. This study set out to evaluate the implications of different sulfur forms on the assessment of acid rock drainage potential using static laboratory-scale tests and to investigate the reliability of methods for the analysis of such forms for the case of three South African coal processing wastes. Both the International Organization for Standardization (ISO) 157:1996 and Australian Coal Association Research Program (ACARP) C15034 protocols were found to be suitable tools for analyzing the different forms of sulfur. Acid-generating sulfur forms constituted between 53% and 64% of the total sulfur in the wastes evaluated, with the maximum potential acidity (MPA) and net acid-producing potential (NAPP) values calculated on the basis of acid-forming sulfur being significantly lower than those calculated on the basis of total sulfur content. Results also showed that the partial conversion of sulfur species under the relatively aggressive conditions of the acid-neutralizing capacity (ANC) and net acid generation (NAG) tests may overestimate the potential acid generating potential in the case of coal. These findings highlight the uncertainties associated with standard ARD static tests and the importance of taking sulfur speciation into account when calculating the MPA for coal processing wastes.

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Mine Waste: Consolidation Behaviour of Precious Metal Tailings

Alberta Academic Review ◽

10.29173/aar41 ◽

2019 ◽

Vol 2 (2) ◽

pp. 29-30

Author(s):

Brandi Goddard ◽

Monica Figueroa ◽

Ahlam Abdulnabi ◽

Nicholas Beier

Keyword(s):

Hydraulic Conductivity ◽

Redox Potential ◽

Electric Conductivity ◽

Precious Metal ◽

Land Reclamation ◽

Acid Rock Drainage ◽

Acid Neutralizing Capacity ◽

Acid Rock ◽

Geochemical Parameters ◽

Neutralizing Capacity

All mine processing plants generate waste. These byproducts include waste rock and a fine-grained slurry referred to as ‘tailings’ (Beier, 2015). The primary objective of treating tailings is to remove water, to enhance strength and stiffness (Sobkowicz and Morgenstern, 2009). Studying the geotechnical properties of tailings is essential to understand consolidation behaviour and facilitate land reclamation. Moreover, the geochemical characteristics of tailings should be examined to examine the potential onset of acid rock drainage (ARD). Acid rock drainage occurs when pH falls below 4, which can cause metal heavy leaching as they become present in solution. This study investigates both the geotechnical and geochemical behaviour of precious metal tailings in atmospheric conditions. The geochemical parameters of interest are pH, redox potential (Eh) and electric conductivity (Ec). The Large Strain Consolidation test (LSC) was implemented to characterize the compressibility behaviour of the sample. Accordingly, the amount of deformation that the tailings underwent was measured as they were loaded to different effective stresses. In addition, the hydraulic conductivity or the velocity of water flow was measured at the end of each consolidation step. Furthermore, the chemical parameters were evaluated using standardized probes. The tailings exhibit high compressibility during self-weight consolidation due to a combination of high initial void ratio and a high initial saturated hydraulic conductivity. In addition, hydraulic conductivity decreases nonlinearly as the samples are loaded because loading reduces the pore volume. The permeability decreased two orders of magnitude during loading, from 2.14E-05 m/s to 1.60E-7 m/s. From the geochemical point of view, there is no significant change in pH as the tailings consolidate. In this scenario, the presence of calcium carbonate has an acid-neutralizing capacity. Moreover, there is a slight increase in both redox potential and electric conductivity due to exposure to the atmosphere. The increasing trend of redox potential had a slope of 10 mV per day. While the slope of electric conductivity was 9 mS/cm per day.

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Identifikasi Batuan PAF, NAF dan UNCERTAIN dengan Menggunakan Metode NTAPP Pada Area PT. Trubaindo Coal Mining, Melak-Kalimantan Timur

Indo J Chem Res ◽

10.30598//ijcr.2019.7-alf ◽

2020 ◽

Vol 7 (2) ◽

pp. 120-126

Author(s):

Alfian Irviansyah ◽

Saibun Sitorus ◽

Aman Sentosa Panggabean

Keyword(s):

Acid Mine Drainage ◽

Coal Mining ◽

Mine Drainage ◽

Ph Value ◽

Acid Neutralizing Capacity ◽

Total Sulfur ◽

Testing Methods ◽

Neutralizing Capacity ◽

Sulfur Level ◽

Actual Acidity

The research about identification of PAF, NAF and uncertain rock using NTAPP method in the PT. Trubaindo Coal Mining has been done. This research was conducted as an effort to control the potential for the formation of acid mine drainage, with identifying the types of mine rocks using certain testing methods. Some important parameters such as Total Sulfur Level, Slurry pH, Total Actual Acidity (TAA), Chromium Reducible Sulfur (CRS) and Acid Neutralizing Capacity (ANC) using the NTAPP method on mine rocks have been determined to identify mining rock category categories. Based on the results of tests on 101 samples, 63 samples were identified included in the category of rocks that are not NAF (Slurry pH value = 4.1 - 8.9; Total Sulfur = 0.01-0.60 %; CRS = 0.01-0.10 % and NTAPP = 0.030-0.959 %), 38 samples were classified as PAF (pH Slurry = 2.9-7.9; Total Sulfur = 0.01-5.10 %; CRS = 0.11-2.04 % and NTAPP = 0.053-4.571 %), and no sample was included in the uncertainty category.

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

Environmental Engineering and Management Journal ◽

10.30638/eemj.2017.216 ◽

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

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Chapter A6. Section 6.6. Alkalinity and acid neutralizing capacity

10.3133/twri09a6.6 ◽

2012 ◽

Cited By ~ 2

Keyword(s):

Acid Neutralizing Capacity ◽

Neutralizing Capacity

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Evaluation of Hemidesmus indicus root as an antacid by In vitro

International Journal of Bioassays ◽

10.21746/ijbio.2016.04.0013 ◽

2016 ◽

Vol 5 (04) ◽

pp. 4524

Author(s):

Abdullah Shaikh Farooque ◽

Md. Azharuddin Ismail Atar*

Keyword(s):

Skin Diseases ◽

Care Delivery ◽

Health Care Delivery System ◽

Acid Neutralizing Capacity ◽

Standard Drug ◽

Hemidesmus Indicus ◽

Neutralizing Capacity ◽

Loss Of Appetite ◽

Powdered Drug

Medicinal plants are being widely used, either as single drug or in combination in health care delivery system. Indian Sarsaparilla, Hemidesmus indicus (Family: Asclepiadaceae) is a commonly known Indian Medicinal Plant, which is widely recognized in traditional systems of Medicine. It contains various phytoconstituents belonging to the category glycosides, flavonoids, tannins, sterols and volatile oils. It has been reported as useful in biliousness, blood diseases, dysentery, diarrhea, respiratory disorders, skin diseases, syphilis, fever, leprosy, leucoderma, leucorrhoea, itching, bronchitis, asthma, eye diseases, epileptic fits in children, kidney and urinary disorders, loss of appetite, burning sensation, dyspepsia, nutritional disorders, ulcer and rheumatism. Several studies are being carried towards its activities like analgesic, anti-inflammatory, antiulcer, hepatoprotective, antioxidant and helicobactericidal properties. In our study we have evaluated antacid activity of sariva (Anantmool) by using In-Vitro method, i.e. ANC (Acid Neutralizing Capacity). This evaluation was done by comparing the ANC of sariva macerated & powdered drug with water as blank & standard drug i.e. NaHCO3. Based on this In-Vitro experiment, we can conclude that, the macerated & powdered drug of sariva (Anantmool) evaluated in this study, varied in potency as measured in terms of their ANC. These results having ** i.e. P < 0.01 & Passed the normality test. However, the present study being in-vitro, the effects of antacid may vary In-Vitro; individual variations also contribute to the ultimate effectiveness of as antacid.

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

Geochemistry Exploration Environment Analysis ◽

10.1144/geochem2021-066 ◽

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.

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