Assessment of bauxite refining residue (red mud) as a liner for waste disposal facilities

Abstract

Red mud (RM), a waste arising from the bauxite refining, was studied to assess its suitability as a compacted liner material. The geotechnical and hydraulic conductivity (K) characteristics of the RM, as well as the effect of desiccation, were evaluated. RM has index properties satisfying the requirements to achieve low K. The compaction-permeability studies showed that RM may be compacted to a dense homogeneous mass using a moderate compactive effort, while lowest K (61 Â 10 À7 cm/s) was achieved for RM compacted slightly (0.4-4%) wet of optimum. Shear strength test revealed high values of friction angle and cohesion for compacted RM, and its tight structure was also evidenced by its low compressibility and maximum settlement under load. Desiccation adversely affected the permeability of compacted RM, but to a lesser extent than generally observed for clays. These results suggest that RM could be potentially utilised as a low-permeability barrier to be laid down under engineered landfill sites.

Compaction and consolidation behaviour of untreated and treated waste of Indian red mud

“…activity <0·75). This observation is in agreement with the findings of Rubinos et al (2015). It has been observed that the activity value of RMW is closer to that of calcite and mica (=0·2) minerals and is comparable to that of the muscovite (≈0·25) mineral, but lower than that of the kaolinite (≈0·4) mineral (Mitchell, 1976;Skempton, 1953).…”

“…The compression behaviour in increasing order is found as sodium chloride > hydrochloric acid > untreated RMW. Evidently, the values of De for both untreated and treated samples are observed to be appreciably lower than that of conventional soils (Rubinos et al, 2015). Generally, in waste materials, the compression mechanism is controlled by applied stresses and changes in physico-chemical processes (Liu et al, 2006;Sowers, 1973).…”

Chemical and environmental compatibility of red mud liners for hazardous waste containment

“…A series of RM specimens were prepared by mixing the pulverised RM with distilled water (24 h of equilibrium) to water contents slightly (*0.5 to 2 %) wet of optimum standard Proctor (w opt = 28.1 %), where compacted RM is at its minimum K (Rubinos et al 2015). Then, the resulting wetted RM mixture was compacted using the standard Proctor (ASTM D698) compaction method, from which undisturbed core specimens of known dry density and water content (Table 2) were obtained and sequentially permeated, firstly with water until steady values of K, then with each corresponding chemical, using a rigid-wall, falling-head, permeameter.…”

“…Due to its geotechnical and adsorptive properties of a wide array of contaminants (Wang et al 2008;Bhatnagar et al 2011), RM has been proposed as a liner material (Kalkan 2006;Ç oruh and Ergun 2010;Rubinos et al 2015). However, the chemical compatibility of RM liners (RMLs) has not been previously studied even though rarely the RML would be exposed merely to water when performing as a hydraulic barrier in actual engineering applications.…”

“…Despite the adequate performance of such materials, some alternative residual materials-fulfilling some minimum requirements (Daniel 1993)-are receiving increasing attention as potential substitutes for natural clays in liners because of cost reasons, limited availability, conservation of natural clay resources, or poor resistance to chemical attack. Examples of these alternative materials (used alone or as admixture) are steel slags (Andreas et al 2014), fly ash (Nhan et al 1996;Hettiaratchi et al 1999;Sivapullaiah and Lakshmikantha 2004), bottom ash (Kumar and Stewart 2003), cement kiln dust (Amadi and Eberemu 2013), and also red mud (Rubinos et al 2015).…”