Evaluating ceramic membranes for the removal of sulfate ions from mine waters
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Journal Title
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Volume Title
Kemian tekniikan korkeakoulu |
Master's thesis
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Mcode
CHEM3043
Language
en
Pages
108+8
Series
Abstract
Water is a key component in the mining and mineral processing industry, which is used widely for the processing of ore, separation of minerals, dust suppression, tailings disposal and human consumption. One of the vital strategic requirements for moving forward is reducing the water withdrawal and improving the usage of mine water for more sustainable mining industry. Thus, developing advanced water treatment technologies has become a high priority in the mining industry worldwide. Ceramic membrane filtration has become more attractive nowadays due to its small footprint, chemical and thermal stability, longer lifetime, and modest energy demand compared to conventional separation processes such as distillation, crystallization, extraction etc. The objective of this study is to enhance the understanding of ceramic membranes and to evaluate the removal of divalent sulphate ions from ceramic membranes in crossflow filtration mode. Comprehensive information on ceramic membranes is provided under literature review including their separation mechanisms and applications. Additionally, the criticality of water in mineral processing operations and current water treatment technologies, specially adapted to remove sulphate ions from mining effluent are introduced. Different types of ceramic membrane modules are commercially available. A comparison is performed to select the optimum ceramic membrane module by considering the material of construction, membrane operation and the geometry of the available ceramic membrane modules to evaluate ion removal from mine waters. Three ultrafiltration ceramic tubular type membranes with different pore sizes are tested using a laboratory membrane filtration testing unit, and synthetic water spiked with sulphate ions is used as the filtering solution. In addition to the effect of pore size for the sulphate removal, the effects of pH of the feed solution, pressure and the presence of other anions and cations in the filtering solution are studied. The sieving mechanism is the predominant separation mechanism in ultrafiltration. However, with the tested ceramic membranes, which have pores relatively larger than the sulphate ions, different amounts of sulphate removal rates are observed. The typical sulphate removal from 5 kDa and 10 nm membranes vary around 4-15% and 3-12% respectively. It is observed that there is a combination effect on sulphate ion retention from membranes by feed solution pH, transmembrane pressure and the presence of different ions.Description
Supervisor
Alopaeus, VilleThesis advisor
Dixon, RichardHiidenheimo, Sakari