Modeling effect of bitumen extraction processes on oil sands tailings ponds

Silawat Jeeravipoolvarn, Warren Miller, J. Don Scott

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Mining Geotechnics

ABSTRACT: In the oil sands industry, high temperature with the addition of a caustic dispersing agent have formed the basis of the Clark Hot Water Extraction process used successfully on a commercial scale to recover bitumen from surface mined oil sands ore since 1967. Processes different from the established Clark process (high temperature and caustic) have been developed to work at a range of temperatures with or without the use of sodium hydroxide. Large scale bitumen extraction pilot tests were performed with two different extraction processes and large strain consolidation tests were performed on the resulting different tailings. These consolidation tests determined the compressibility and hydraulic conductivity relationships with void ratio which are engineering properties that influence the long-term disposal of the fine tailings. They were used in large strain consolidation numerical analyses of storage ponds to predict water release rates and changes to surface elevations that impact storage volumes and elevation of reclamation surfaces. RÉSUMÉ Dans l'industrie des sables bitumineux , à haute température avec l'ajout d'un agent de dispersion caustique ont formé la base du processus d'extraction de l'eau Clark chaude utilisée avec succès à une échelle commerciale pour récupérer le bitume de surface extrait ce minerai depuis 1967 . Processus différente de la place processus Clark (haute température et caustique) ont été développés pour fonctionner dans une plage de températures, avec ou sans l'utilisation de l'hydroxyde de sodium. Des essais pilotes d'extraction de bitume à grande échelle ont été réalisés avec deux différents procédés d'extraction et de grands essais souche de consolidation ont été effectués sur les différents résidus qui en résultent. Ces essais de consolidation ont déterminé la compressibilité et les relations de conductivité hydraulique avec l'indice des vides qui sont l'ingénierie des propriétés qui influent sur le stockage à long terme des résidus fins . Ils ont été utilisés dans de grandes analyses numériques souche de consolidation des bassins de stockage de prédire les taux de rejet de l'eau et des changements à des altitudes de surface que les volumes de stockage de l'impact et l'élévation des surfaces de remise en état. 1 INTRODUCTION In the oil sands industry, high temperature and addition of caustic (NaOH) form the basis of the caustic process used successfully to recover bitumen from surface mined oil sands ore. However, the caustic process results in the creation of extremely dispersed, high void ratio fine tailings composed primarily of silt, clay, water and residual bitumen. These caustic-affected fine tailings exhibit extremely low consolidation rates and shear strengths and require considerable real estate for surface storage. Non-caustic processes have been developed to improve bitumen recovery, improve the process water chemistry and reduce the dispersion of fines during bitumen extraction. Producing tailings with reduced fines dispersion should improve the consolidation and strength properties of the fine tailings. A potential reduction in fine tailings volume and improved geo-environmental behaviour provided an environmental and economic incentive to examine the relative differences between the characteristics of the fine tailings derived from a caustic and a non-caustic extraction process. Large strain consolidation tests were performed on both caustic and non-caustic fine tailings to determine the relationships effective stressŒvoid ratio and void ratioŒhydraulic conductivity. These relationships are used in large strain consolidation analyses of a storage pond to predict water release rates and changes to surface elevations that impact storage volumes and elevation of reclamation surfaces. The analyses were first used to model long term one meter high standpipe tests on both materials to verify the large strain consolidation test results and the analyses equations used in modelling. They were then used in consolidation analyses of commercial scale tailings ponds to examine the benefit of non-caustic tailings in long term tailings disposal. 2 OIL SANDS AND EXTRACTION METHODS Fine tailings were generated from 80 tonne samples of typical Suncor Energy Inc. ore that was processed using both a caustic and a non-caustic extraction method. The extraction process water was determined based on the water source that would be used for commercial operation. Recycled pond water from Syncrude's Mildred

RÉSUMÉ: ing effect of bitumen extraction processes on oil sands tailings ponds

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Cite this article:
Silawat Jeeravipoolvarn; Warren Miller; J. Don Scott (2014) Modeling effect of bitumen extraction processes on oil sands tailings ponds in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper258,author = Silawat Jeeravipoolvarn; Warren Miller; J. Don Scott,title = Modeling effect of bitumen extraction processes on oil sands tailings ponds ,year = 2014}