Bioleaching of clays and iron oxide coatings from quartz sands

Silica sands of low quality contain free iron oxides, clay and silt. These impurities may be removed by biological leaching as well as by industrial washing. The fine fractions obtained from industrial washing of quartz sand from Šastín, Slovakia, with a higher content of iron-bearing minerals and c...

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Bibliographic Details
Published in:Applied clay science 2012-06, Vol.61, p.1-7
Main Authors: Štyriaková, Iveta, Mockovčiaková, Annamária, Štyriak, Igor, Kraus, Ivan, Uhlík, Peter, Madejová, Jana, Orolínová, Zuzana
Format: Article
Language:English
Subjects:
Bacillus spp
Bacteria
Bacterial leaching
Bioleaching
Biological
Clays
Earth sciences
Earth, ocean, space
Exact sciences and technology
Heterotrophic bacteria
Iron
Iron oxides
Mineralogy
Quartz
Quartz sands
Sands
Silicates
Surface chemistry
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Summary:Silica sands of low quality contain free iron oxides, clay and silt. These impurities may be removed by biological leaching as well as by industrial washing. The fine fractions obtained from industrial washing of quartz sand from Šastín, Slovakia, with a higher content of iron-bearing minerals and clay minerals were used to study bioleaching of impurities of the quartz sands. The influence of biological leaching by indigenous heterotrophic bacteria and Bacillus spp. bacteria was evaluated by changes in chemical composition of the fine fractions before and after reaction. The bioleaching experiments were performed for 63days at 24°C. The extracted iron and clay products were characterized by XRD, FTIR, Mössbauer spectroscopy, chemical and granulometric analyses, SEM, EDX, and nitrogen adsorption techniques. The bacteria assisted in releasing the poorly ordered clay minerals from the surface of quartz particles via dissolution of amorphous Fe oxyhydroxides. ► The fine fractions of quartz sands formed the surface impurities on quartz grains. ► The bioleaching of the fine fraction caused a break of the minerals binding. ► The poorly ordered clay minerals was released via dissolution Fe mineral. ► The bioleaching experiment explains the purification process of quartz sands.
ISSN:0169-1317
1872-9053
DOI:10.1016/j.clay.2012.02.020