Abstract
The solidification of copper mine tailings was investigated by using the natural biological process known as microbial induced calcium carbonate precipitation (MICP) as a potential method to valorize this waste stream. A submergent method was used to grow bio-columns and the toxicity of copper on Sporosarcina pasteurii (the ureolytic bacteria which drives the MICP process) was investigated. The bio-columns produced from copper mine tailings had a compressive strength of 0.54 MPa, lower than bio-columns produced from beach sand (1.85 MPa). The low porosity of the copper mine tailings limited the depth to which the MICP reaction could successfully occur, resulting in a 1.8 mm ± 0.4 mm crust forming around the outer extremities of the bio-columns. The results demonstrated that the particle size was a key deciding factor and that, as a result, MICP is not suitable for producing ‘thick’ bio-cemented materials from small particles (<100 μm) such as mine tailings. However, this method could produce thinner material such as bio-tiles or it could even be used to potentially cement together toxic dust particles typically formed on mine tailing heaps.
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