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Remediation of acid mine drainage using natural zeolite

Motsi, Tafadzwa (2010)
Ph.D. thesis, University of Birmingham.

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Abstract

This research focuses on the removal of Fe, Cu, Zn and Mn from synthetic metal solutions and real AMD from Wheal Jane mine using natural zeolite. Laboratory experiments were performed to investigate the effectiveness of natural zeolite as a potential low cost material for the removal of these heavy metals from AMD. These include, equilibrium tests, batch kinetic studies, column studies and desorption studies.

Equilibrium studies showed that the capacity of natural zeolite for heavy metals increased with an increase in initial solution pH. Fitting of the Langmuir and Freundlich isotherms to experimental data gave good fits, R\(^2\) values ranging from 0.9 – 0.99. The selectivity series of natural zeolite was: Fe\(^{3+}\)>Zn\(^{2+}\)>Cu\(^{2+}\)>Mn\(^{2+}\). The amount of exchangeable cations increased at equilibrium, indicating that ion exchange had taken place. Higher metal uptakes were achieved by increasing agitation speed, initial solution pH, particle size reduction, and thermal pre-treatment. The rate limiting step for this process was intraparticle diffusion.

Column studies showed that natural zeolite was capable of removing heavy metals from a continuously flowing solution. The breakthrough time increased with a longer bed height and slower flow rate. The bed depth service time model (BDST) was used to simulate experimental data and deviated from these by 12 – 14%.

The treatment of actual Wheal Jane mine AMD showed that about 71-99% Fe and 97-99% Cu were removed from solution. Results from the treatment of actual AMD revealed that natural zeolite was best suited for treating dilute metal solutions, and hence should be used downstream of other AMD treatment technologies.

Type of Work:Ph.D. thesis.
Supervisor(s):Rowson, Neil and Simmons, Mark J. H.
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Chemical Engineering
Subjects:TN Mining engineering. Metallurgy
Institution:University of Birmingham
ID Code:683
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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