TREATMENT OF ACID ROCK DRAINAGE (ARD) WITH A LIMESTONE BUFFERED ORGANIC SUBSTRATE (LBOS) IN A VERTICAL FLOW CONSTRUCTED TREATMENT WETLAND

Aspergillus niger is a prominent fungi that has been used for bioleaching of nickel laterite ore and commercial production of citric acid. Series of shake flask bioleaching assays have been conducted to study the effects of ore type, ore particle size distribution, solid percentage, and substrate volume percentages as well as sulphur addition on the nickel extraction from Indonesian laterite ore. Acid rock drainage (ARD) from local coal mine was used as a substrate for carbon and nutrient sources of the fungus. The results show that saprolite ore exhibits a better leaching with fungal metabolic acids than limonite. The highest nickel extraction of saprolite ore was 43%, which was obtained from the shake flask bioleaching assays with ore particle size distribution of -60+80 mesh, pulp density of 2.5%, and ARD substrate volume percentage of 10%, after 24 days of incubation. For both saprolite and limonite ore samples, coarse particle size ditribution of -60+80 mesh provides a better nickel extraction than the finer ore particle size. The addition of potato dextrose agar and fresh innoculum after 16 incubation days generated a re-increase of nickel extraction, indicating the refreshment of the active fungus. Based on the results, it was found that Aspergilus niger growth can take place with an organic substrate of liquid ARD obtained from coal mining area.

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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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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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