Geotextile tubes filled with mine tailings as a construction element

Abstract

Large quantities of mine tailings are stored in mine tailings storage facilities. These facilities are only costing money for mining companies. In addition, these tailings storage facilities are prone to failure. To prevent this from happening these facilities have to be reinforced. This research introduces a concept to use geotextile tubes filled with mine tailings as reinforcing construction elements. That way value is assigned to the mine tailings while also making the storage facilities safer. However, pumping mine tailings in geotextile tubes is not an option due to the small particle sizes which will flow through the openings in the geotextile fabric. In addition, the contaminations in the mine tailings will also be mobilised using this method. Therefore, this research investigates potential enhancement of mine tailings to make them suitable to be pumped in geotextile tubes. The potential enhancement is in the form of flocculation and remediation. While flocculation increases the dewatering properties of mine tailings, the remediation will prevent the contaminations from mobilising. Test performed in this research include a series of jar tests, cone tests, two different strength tests and hanging bag tests. The results show that when flocculants are added to the tailings, the dewatering rate increases. The flocculant type which proved the most effective for these specific tailings type is a flocculant with an average molecular weight and average anionic value. Adding coagulant to the tailings further increases the dewatering rate of the tailings. When Ordinary Portland Cement is added, to stabilise and solidify the tailings, the dewatering rate increases even more. In addition, adding Ordinary Portland Cement to the tailings resulted in an increase of shear strength and unconfined compressive strength. After seven days of curing, the highest strength of curing was measured for the mixtures where fifteen mass percentage Ordinary Portland Cement was added. The mixture where the highest strength and the fastest dewatering rate was measured, was the mixture composes of mine tailings, flocculants, coagulants and fifteen mass percentage Ordinary Portland Cement.
With these results, it may be concluded that mine tailings can be used to fill geotextile tubes to form reinforcing construction elements if its dewatering behaviour is enhanced and its contaminants remediated.