Polymer-modified tailings deposition – ongoing testing and potential storage efficiency opportunities

Abstract

An emerging technology, known by various names such as in-line flocculation, polymer modified tailings deposition or more commercially as enhanced tailings disposal (ETD), is the subject of growing interest from mining operations. Business drivers for the mine tailings facility owners can include a variety of site-specific, material-dependant operational challenges, as well as more general desires to improve efficiency at tailings storage facilities (TSFs). Polymers can modify the behaviour of tailings in a variety of ways; one of these is through rheological adjustment. This can often result in a steepened beach which, with careful design and use of natural or man-made landforms, can result in the potential for significant reduction in the volume of initial embankment construction material. These opportunities are the subject of a number of ongoing large-scale operational trials that are likely to become the topic of future papers. Other material behavioural changes are inextricably linked with the technology. These include reduced segregation, improved water release, less long-term settlement, and improving permeability and subsequent consolidation behaviour. Thorough understanding of these improvements can allow for appropriate design and operational management, which can then allow the operator leverage to improve long-term operational performance. This paper describes some scoping-level testing that focused on potential time-related opportunities that may lead to more efficient tailings management. Subject to site-specific constraints, there may be a costeffective opportunity to defer future capital expenditure required for construction of a subsequent facility, or construction of the next raise of the embankments. Increased consolidation rates may also lead to improved trafficability and thus more efficient rehabilitation. Whilst not going into specific detail concerning operational or construction costs, this paper presents high-level results of testing and consolidation modelling, demonstrating a combination of opportunities for improved tailings performance through the implementation of the following:  Accelerating and increasing overall water release.  Improving the rate of consolidation.  Reducing the rate of rise.  Reducing the amount of post depositional settlement. The implications of the data and modelling are discussed in the context of potential business opportunities, which can be broadly described as the 'time value of volume'.

Large strain shearing behaviour of untreated and polymer treated clayey silt slurry specimens

“…Owing to the increased application of forms of PT, studies to characterise the effects PT may have on post-deposition geotechnical behaviour of the treated slurry have been undertaken. Broadly, these studies have indicated the following effects of PT: lower consolidated densities at a given vertical effective stress and higher permeability at a given density (Jeeravipoolvarn et al 2009;Yao 2012;Manzotti et al 2014;Beveridge et al 2015;Gholami & Simms 2015;Reid & Boshoff 2015;Riley et al 2015;Znidarcic et al 2015;Reid & Fourie 2016, 2018aAbdulnabi et al 2022), higher undrained shear strengths at a given density (Jeeravipoolvarn et al 2009;Yao 2012;Beier et al 2013;Manzotti et al 2014;Cooling & Beveridge 2015;Gholami & Simms 2015;Reid & Fourie 2016Abdulnabi et al 2022) and higher CSL elevation (Reid & Fourie 2016), and various contrasting outcomes when examining the effects of PT on brittleness in undrained monotonic or post-cyclic shearing (Beier et al 2013;Gholami & Simms 2015;Reid & Fourie 2017) and drastically different penetrometer responses (Reid and Fourie 2018a), with a summary of recent studies provided by Reid and Fourie (2018b).…”

Dewatering polymer application in an iron ore tailings dam

“…The method of applying polymers to treat tailings is known as in-line flocculation or in-line polymer addition (Wells and Riley, 2007., Bembrick, 2008., Wells et al 2011., Mizani, 2013., Guang et. al, 2014., Riley and Utting, 2014., Guang and Longo, 2017., Costine et al, 2018.…”

Geotechnical effects of polymer treatment on tailings – state of knowledge review

“…Attempts to improve the dewatering behaviour of tailings through the addition of polymers at the point of discharge appear to have been first attempted in the early 1980s on coal tailings (Backer & Busch 1981;Stewart et al 1986). Significant interest has developed more recently, with a variety of applications on a number of tailings types over the past 10 years (Cooling & Beveridge 2015;Jeeravipoolvarn et al 2009;Riley et al 2015). An area of particular focus has been mature fine tailings (MFT), which is the very fine tailings resulting from processing oil sands, owing to the closure challenges related to that material type.…”