Effect of ore type on the leaching and biosorption characteristics of lead from waste cupels using spent tea leaves (camellia sinensis)
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2019-06
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ABSTRACT
Waste cupel samples from two commercial gold fire assay laboratories in Ghana were sampled
and characterized. The selection of the fire assay laboratories was based on the type of ore being
processed. Comparative study of the effect of ore type (oxide and sulphide) on the leaching and
biosorption characteristics of lead from waste cupels using spent tea leaves (Camellia sinensis)
was investigated. Both laboratories use magnesia (MgO) cupels. Waste cupel samples were
collected, pulverised and characterized prior to acid digestion. The mineralogical and chemical
compositions were determined using X-ray Diffraction and Inductively Coupled Plasma
Optical Emission Spectroscopy / Mass Spectroscopy, respectively. Leachates from the waste
cupels were contacted with spent tea leaves and the biosorption efficiency and specific metal
uptake determined. Results show that lead concentrations in waste cupels from oxide ore
(CWO) increased as particle sizes increased whilst lead concentration from sulphide ore (CWS)
decreased with increased particle sizes. The biosorption efficiency of lead was higher in CWO
leachate ( > 99 %) than in CWS leachate ( < 98 %). For a given biomass concentration, CWO
recorded a higher specific metal uptake as compared to CWS. The specific metal uptake in both
samples were affected by the volume of leachate and lead concentration in leachate. In both
samples, the adsorption isotherms fitted well in Langmuir model. The results from this study
indicate that spent tea leaves can be used as an adsorbent to render waste cupels non-toxic
before disposal.
Description
A thesis submitted to the Department of Materials Engineering, in partial fulfilment of the requirements for the degree of Master of Philosophy Environmental Resources Management