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Numerical evaluation of one-dimensional large-strain consolidation of mine tailings

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dc.contributor.authorAgapito Tito, Luis Angel, author
dc.contributor.authorBareither, Christopher A., advisor
dc.contributor.authorShackelford, Charles D., advisor
dc.contributor.authorSutton, Sally J., committee member
dc.date.accessioned2016-01-11T15:13:46Z
dc.date.available2017-01-07T06:30:24Z
dc.date.issued2015
dc.description.abstractThe objective of this study was to evaluate the applicability of commercially-available, one-dimensional (1-D) large-strain consolidation programs (FSConsol and CONDES0) for predicting mine tailings consolidation to estimate storage capacity of tailings storage facilities (TSFs). This study consisted of the following tasks: (i) consolidation modeling of well-known benchmark examples from literature, (ii) parametric study to assess the influence of input parameters (i.e., constitutive relationships, initial void ratio, impoundment geometry, and tailings production rate) on consolidation behavior and storage capacity, and (iii) consolidation and storage capacity prediction for a full-scale copper TSF. A benchmark example that represented instantaneous deposition of tailings (Townsend and McVay 1990) was evaluated with CONDES0 and FSConsol and indicated that both models are appropriate for predicting the consolidation behavior of tailings that are deposited instantaneously. Both models yielded similar temporal settlement curves and void ratio profiles. A gradual tailings deposition benchmark example (Gjerapic et al. 2008) was evaluated with both programs and suggested that FSConsol was more applicable for problems dealing with continuous discharge of tailings. In particular, FSConsol was more applicable when the tailings discharge rate varied temporally, which is a key constraint to modeling a full-scale TSF. The parametric study results suggested that the initial tailings void ratio and constitutive relationships (i.e., void ratio versus effective stress, e-σ', and hydraulic conductivity versus void ratio, k-e) had more pronounced effects on consolidation behavior relative to impoundment geometry and tailings production rate. In particular, a comparison between rapidly consolidating mine tailings (copper tailings) and slowly consolidating mine tailings (mature fine tailings from oil sands) indicated that a decrease in hydraulic conductivity by four orders of magnitude can extend the time required for consolidation by more than 200 yr. Changes in impoundment geometry and tailings production rate had limited effects on impoundment capacity for the range of side slopes (1.0H:1V to 4.5H:1V) and production rates (50 mtpd to 300 mtpd) evaluated in this study. FSConsol modeling results from the full-scale copper mine TSF were compared to field data and suggest that a 1-D consolidation model can yield a satisfactory prediction of in-situ consolidation behavior of copper tailings. Comparison between the actual average tailings dry density (ρd) during the first 4 yr of operation and predicted average ρd yielded coefficients of determination (R2) as high as 81 % and 93 % for Operation and Design assessments, respectively. In addition, predicted tailings height within the TSF showed good agreement with actual impoundment heights for the first 6 yr of operation; R2 = 99.1 % for the Operation assessment and cyclone operation time (COT) of 70 %, which was the average actual COT. A procedure was developed to predict average ρd of a full-scale TSF using a 1-D consolidation model that includes the following considerations: (i) estimate total tailings volume in the TSF based on predicted impoundment height and (ii) use this total volume with dry tailings mass discharged into the TSF to compute ρd. The main finding from this study was that the modeling of gradual tailings deposition with FSConsol provides a reliable prediction of impoundment height and impoundment capacity.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.identifierAgapito_colostate_0053N_13305.pdf
dc.identifier.urihttp://hdl.handle.net/10217/170334
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectconsolidation
dc.subjectcopper
dc.subjectmine
dc.subjecttailings
dc.subjecttailings storage facility
dc.titleNumerical evaluation of one-dimensional large-strain consolidation of mine tailings
dc.typeText
dcterms.embargo.expires2017-01-07
dcterms.embargo.terms2017-01-07
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineCivil and Environmental Engineering
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)

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