Development of compact fluorescent spectrometers and field deployable optical solids content monitoring devices

  • Author / Creator
    Ho, Timothy Then-Siong
  • Two techniques were used to develop industrial and environmental sensing devices: fluorescence spectrometry and light scatter. The focus of the thesis is to develop real-time, portable and economical sensors using these techniques for environmental detection and management of tailings slurries. A compact fluorescence spectrometer compatible with cone penetration was developed for hydrocarbon contamination in soils. To be compatible, the device was designed to fit into a 25 mm diameter tube. To simplify the alignment of optics in a small space, 5 long-pass filters were used to divide the fluorescence spectrum for spectral analysis. A 405 nm wavelength laser diode was used as the excitation source because of its high output, sufficiently high photon energy and cost-effectiveness. Fluorescence results were obtained and show capability to differentiate between several fluorescence spectra. The light scatter intensity of highly concentrated slurries, typically 30% w/w to 70% w/w, was investigated using blue (405 nm wavelength) and red (639 to 650 nm wavelengths) laser diodes. First, a small test cylinder was used to learn about the relationship between light scattered and solids content of a sample. A ring device was also constructed for use with cuvettes to analyse the angular distribution of the light scatter and light scatter intensity for various samples including different tailings slurries and polystyrene beads. This ring was also used to develop a calibration relationship between solids content and relative amount of light scattered. Using the relationship established, 3 different sensor systems were developed under differing criteria to measure concentration (or solids content) of slurries undergoing 3 methods of dewatering. A centrifuge sensor was made to withstand 100 times gravity and measure in real time. A 3 m tall device was built to continuously monitor the progress of tailings with flocculants settling over the course of a year. Finally, a sensor was designed to measure changing solids content of slurries being actively processed in a pipeline, using a credit-card sized economical microprocessor as the main computation device. These three devices were field tested and show light scatter sensitivity to the changing solids content.

  • Subjects / Keywords
  • Graduation date
    Spring 2015
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.