Rheomax™ and Water Conservation at Orapa Mine

Vietti, Andrew; H, Cooke R; Ntshabele, Keabetswe; Cooks, Martin; Busani, Bernard

doi:10.36487/acg_repo/863_32

Cited by 5 publications

(2 citation statements)

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“…Polymer treatment of tailings to increase the rate of dewatering, increase shear strength, reduce segregation, and promote a steeper beach angle is an emerging technology of increasing popularity (Dymond 2003;Kaiser et al 2006;Adkins et al 2007;Brumby et al 2008;Vietti et al 2008;Daubermann & Földvári 2008da Silva 2011;Wells et al 2011). While the implementation of PT has been shown often to result in improved behaviour as desired for the proposed steepened beach concept outlined herein, it has also been shown to affect the geotechnical behaviour of tailings.…”

Section: Geotechnical Effects Of Polymer Treatmentmentioning

confidence: 98%

Stability of a proposed steepened beach

Reid¹,

Boshoff²

2015

Proceedings of the 18th International Seminar on Paste and Thickened Tailings

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Existing topography at an operational lateritic nickel facility is such that if the tailings beach slope could be increased to 1-2% for approximately one year, significant costs related to wall building could be deferred. As additional thickening capacity would require significant capital expenditure, polymer treatment technologies have instead been investigated. As part of the trial process for polymer treatment, the stability of the potential steepened beach was assessed. While beach slopes of the range targeted here would, for many materials, be unlikely to produce an unstable landform, lateritic nickel tailings develop very low dry densities, consolidate slowly, and contain hypersaline pore fluid. This combination results in a lower resistance to slope instability, all else being equal. Further, polymer treatment technologies, while providing benefits through rapid dewatering and beach slope development, have been shown to result in an increased brittleness for some materials. Laboratory characterisation of the polymer treated material was first undertaken, by means of (i) monotonic, cyclic and post-cyclic simple shear testing, to assess the potential for strength loss of the material, (ii) laboratory-scale shear vane testing, to estimate residual shear strength, and, (iii) settling and consolidation tests, to provide input to consolidation modelling. A consolidation model of the proposed steepened beach was then developed. Outputs from this model were used as the basis for infinite slope stability analyses on a variety of scenarios. It was found that over the one year planned deposition period, beach slopes of 1.5% or less are likely to result in a satisfactory factor of safety (FS) for the steepened beach. 2 Previous relevant studies 2.1 Steepened beach stability A number of previous studies have been undertaken to assess the expected stability of proposed unconstrained tailings beaches, most of which were developed from thickened tailings deposition. Each of

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Section: Geotechnical Effects Of Polymer Treatmentmentioning

confidence: 98%

Stability of a proposed steepened beach

Reid¹,

Boshoff²

2015

Proceedings of the 18th International Seminar on Paste and Thickened Tailings

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“…Although some projects may benefit from a steepened beach concept to reduce the early capital cost of embankment construction through the use of polymer treatment, other projects may benefit from the process in other ways (Dymond 2003;Kaiser et al 2006;Adkins et al 2007;Brumby et al 2008;Vietti et al 2008;Daubermann & Földvári 2008da Silva 2011;Riley & Utting 2014).…”

Section: Introductionmentioning

confidence: 99%

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

Riley¹,

Reid²,

Utting³

2015

Proceedings of the 18th International Seminar on Paste and Thickened Tailings

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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'.

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