Subscriber access provided by UNIVERSITY OF TOLEDO LIBRARIES
Article
Rapid Determination of Bitumen Content in Athabasca Oil Sands by Laser-Induced Breakdown Spectroscopy Aissa Harhira, Josette El Haddad, Alain Blouin, and Mohamad Sabsabi Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b03821 • Publication Date (Web): 31 Jan 2018 Downloaded from http://pubs.acs.org on February 10, 2018
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Energy & Fuels is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
Rapid Determination of Bitumen Content in Athabasca Oil Sands by Laser-Induced Breakdown Spectroscopy Aissa Harhira*, Josette El Haddad, Alain Blouin, Mohamad Sabsabi Energy, Mining and Environment Research Centre, National Research Council Canada, 75 de Mortagne Blvd., Boucherville, QC J4B 6Y4, Canada
KEYWORDS Oil sands, Bitumen, LIBS, Spectroscopy
ABSTRACT
Evaluation of bitumen content in oil sands feedstock is important to control extraction process and improve the recovery efficiency. Current standard techniques for bitumen determination in oil sands ore suffers whether from their time consuming labor intensive method of sample preparations or from requiring a high number of samples for calibration purposes. The analysis of bitumen ore samples is very challenging for the analytical chemist due to its nature of several phases of wet and dry particles and heterogeneous mixture of clay, bitumen, water and solid
ACS Paragon Plus Environment
1
Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 19
contents. In this paper, we present a new enabling method using LIBS to determine rapidly and without sample preparation the bitumen content in oil sands ores. A qualitative study by principal component analysis was first done, and then a partial least squares method was performed to assess the feasibility of determining bitumen by LIBS. The results show a good correlation between LIBS spectra and bitumen content and a prediction averaged absolute error around 0.7%. This method demonstrates that the LIBS is a promising tool for rapidly assessing oil sands ore grades either in the lab, at-line or on-line. Elemental composition of solids is also investigated.
Introduction The Athabasca oil sands (Canada) are considered to be the largest oil sand reserves in the world1. Oil sands are heterogeneous mixtures composed of about 4% to 18% of bitumen, about 55% to 80% of mineral solids including coarse sand, silt and clay and about 2%to 15% of water2. Oil produced from oil sands by surface mining methods involves the basic steps of mining the oil sands, slurry phases for separation, bitumen recovery by flotation, upgrading for synthetic oil and finally refining. Prior to the recovery of bitumen by flotation, it is important to characterize the oil sands feedstock ore content to optimize the process and make decision on recovery efficiency and economic value perspectives. These measurements can be done in the laboratory or on an apron feeder to monitor the feedstock. However, current methods for assessing oil sands content are time consuming and labor intensive as well as difficult to control due to the complexity and heterogeneity of the samples that contain different particle sizes and several components. The industry standard for determining bitumen, water, and solids contents of oil sands ore samples is the Dean-Stark extraction method3. Full extraction of bitumen from the solids can often take hours to complete. Once the three components have been physically separated, they can be
ACS Paragon Plus Environment
2
Page 3 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
quantified by various means. The clean and dry solids can be further analyzed by a variety of techniques, including elemental analysis by inductively coupled plasma (ICP) or X-ray fluorescence (XRF), and mineralogy by X-ray diffraction (XRD). The Dean-Stark extraction method requires large amounts of expensive solvents and suffers from time consuming labor intensive method of sample preparations. Low field nuclear magnetic resonance (NMR) spectroscopy has also been used for measuring bitumen and water4. Although that solid content can be determined by the difference between the total content and the water and bitumen contents, the technique cannot give atomic elemental and mineralogical information. Nearinfrared reflectance (NIR) measurements between 800-2500 nm have been used to estimate the bitumen content since the early 1990s5,6. Despite substantial efforts to improve reliability and robustness of NIR analyzers, the technique still requires huge number of samples for calibration purposes while providing limited information. Due to these difficulties mentioned above, there is a need in oil sand industry for a breakthrough technology able to determine the content of bitumen quickly and without sample preparation in the laboratory or online. Laser induced breakdown spectroscopy (LIBS) appears to be a potential candidate technique to fulfill the requirements of the oil sands industry. The technique has already been used to characterize other types of mining and geological materials7-9 as well as to monitor mineral processings10,11. LIBS is a spectroscopic technique which uses a high power pulsed laser beam focused onto a sample to ablate a small quantity of materials from the sample surface, typically a few nanograms, and create a hot temperature plasma where atoms and ions are in excited state. As the plasma cools, the atoms and ions return to their fundamental states by emitting radiation. This emitted radiation is detected by a spectrometer. Wavelengths of either atomic transitions or molecular bands12 provide qualitative information on the chemical
ACS Paragon Plus Environment
3
Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 19
composition of the ablated material and the spectral intensities are related to the content concentrations. In addition to the ability to measure simultaneously several atomic elements, LIBS can measure light elements (Z
