Assessing the Potential of Laterite in Adsorbing Cadmium from Mine Leachate and Surrogate Cadmium Solutions: A Case Study at Anglogold Ashanti Iduaperiem Gold Mine Ltd, Tarkwa

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2015-02-10
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Increased mining activities have resulted in the generation of huge stockpile of waste rocks. Subsequent heavy metal laden leachate emanate from these waste rocks. This has resulted in deleterious effects on adjacent water bodies and ecosystem thus posing issues of health and environmental concerns. Waste rock samples were obtained from two active waste rock dump sites. The waste rocks were characterized using XRF and XRD. Leach test was then performed using US Geological Survey Field Leach Test (USGS FLT). Batch and columns test were conducted using United State Environmental Protection Agency (USEPA) batch type procedures for estimating soil adsorption of chemical elements (eg. heavy metals). Cadmium level of 0.0505 mg/l obtained from the leach test exceeded WHO’s guideline value of 0.03mg/l for potable water. Optimal time, pH, adsorbent dosage, temperature and initial concentration of 1hour, 9, 10 g, 20 0C and 10 mg/l respectively were obtained from the batch tests. Langmuir isotherm provided a better fit for the experimental data resulting in a maximum adsorption capacity of 10689.31mg/g. From the ΔG° values (-1027.98, -147.23, -249.63, -662.87, -1765.21) J, ΔS° value (36.9726) and ΔH° value (10432.36) J obtained from the thermodynamic study, it can be inferred that adsorption of cadmium onto laterite is feasible, spontaneous and endothermic. Breakthrough time of 3 hours and exhaustion time of 11 hours were established from the column tests. Hence laterite proves as an appropriate adsorbent for cadmium.
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A Thesis Submitted to the Department Of Materials Engineering, in partial Fulfillment of the Requirement for the Award of a Master Of Science (Msc) Degree in Environmental Resources Management of Resources and Environment, 2014
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