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Rheology modification of TT to enhance inline re-flocculation

IP.com Disclosure Number: IPCOM000246389D
Publication Date: 2016-Jun-02
Document File: 4 page(s) / 92K

Publishing Venue

The IP.com Prior Art Database

Abstract

This method describes a means of transporting oil sand slurry from a tailings treatment facility to a deposition area by adjusting the rheology for pumping and re-flocculation purposes. This invention is an improvement of the conventional approach were slurries are diluted by water addition to modify thickener underflow rheology in order to provide a suitable carrier fluid for Thickened Tailings (TT) for secondary flocculation and transportation to deposition with minimum segregation. The present method allows for modification of thickened tailings rheology by altering the clay to water ratio (CWR) through addition of Fluid Fine Tailings (FFT) or Mature Fine Tailings (MFT) and or rheology modifiers in order to improve process control and efficient mixing of viscous flocculants and high solids thickened tailings for better flocculation and transport to the deposit. The blending allows for formulating a suitable feed for re-flocculation and helps transport. The proposed modification allows for better utilization of flocculants, as MFT will not be flocculated twice and also allows for better utilization of thickener overflow water, as it is not added back to the TT stream after prior removal. An additional benefit is better thickener capacity utilization. If required additional MFT can be added to the thickener feed to enable better control of the thickening process.

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Title: Rheology modification of TT to enhance inline re-flocculation

Abstract:

This method describes a means of transporting oil sand slurry from a tailings treatment facility to a deposition area by adjusting the rheology for pumping and re-flocculation purposes. This invention is an improvement of the conventional approach were slurries are diluted by water addition to modify thickener underflow rheology in order to provide a suitable carrier fluid for Thickened Tailings (TT) for secondary flocculation and transportation to deposition with minimum segregation. The present method allows for modification of thickened tailings rheology by altering the clay to water ratio (CWR) through addition of Fluid Fine Tailings (FFT) or Mature Fine Tailings (MFT) and or rheology modifiers in order to improve process control and efficient mixing of viscous flocculants and high solids thickened tailings for better flocculation and transport to the deposit. The blending allows for formulating a suitable feed for re-flocculation and helps transport. The proposed modification allows for better utilization of flocculants, as MFT will not be flocculated twice and also allows for better utilization of thickener overflow water, as it is not added back to the TT stream after prior removal. An additional benefit is better thickener capacity utilization. If required additional MFT can be added to the thickener feed to enable better control of the thickening process.

Problem Statement:

Treating oil sand tailings has been a challenge to the industry since the 1960s, and several technologies are currently being applied and tested. Several of these technologies have varying successes in the treatment of MFT. All commercial oil sands operators use variations of the Clark hot water process, where caustic is added as a dispersant to enable liberation of bitumen from solids in aqueous pulp. Oil sand tailings consist of unrecovered bitumen, residual water and solids. The solids can be separated into fines and sands fractions. The fines fraction requires containment to allow water to drain out and for strength gain which poses a demand for storage volume and also recycling water. Thickening is one approach which has been successfully used in the mineral industry and is just finding a niche in the oil sands industry.

When operated with classifiers, thickeners can be efficiently operated, but the absence of prior particle size classification in some operations running thickeners poses challenges in running these systems as there is no good control of the feed coming to the thickener. Variation in feed Sand to Fines Ratio (SFR) poses challenges to both primary and secondary flocculation. The main challenges are associated with high SFR is increased risk for segregation during both thickening and transport. Additional challenges include exceeding thickener rake torque, underflow pumpability, pumping and secondary flocculation. For these systems rheology modification p...