A real time in situ light-scattering technique for tailings solids content measurement: Near-infrared versus visible wavelengths

Abstract

Optical scattering can be potentially used to develop an effective solids content measurement tool for tailings ponds monitoring and management. This bench-scale study investigated suitable laser wavelengths in both visible (405, 520 and 658 nm) and near infrared (980, 1310 and 1550 nm) ranges for real time in situ application in oil sands tailings. In general, the near infrared wavelengths demonstrated higher sensitivity over the entire test range compared to the visible wavelengths. Furthermore, residual bitumen in oil sands tailings tended to absorb the visible wavelengths, which interfered with the scattering light signals, leading to inaccurate measurements. Due to a sufficiently strong water absorption, the 1550 nm wavelength in particular showed an almost linear sensitivity of the light scattering with the change in solids concentration with a 1.5% accuracy and was able to overcome the effects of the variation in the physical and chemical properties of the samples including particle size distributions. Conveniently, the absorption was not strong enough to generate noise in the measurement caused by atmospheric moisture. The 1550 nm wavelength was identified as a promising candidate for the light scattering-based solids content analyzer for real time in situ tailings ponds monitoring. • Light scattering technique for real time in situ solids content measurement. • Investigate wavelengths from visible to near infrared. • 1550 nm wavelength demonstrated sensitivity to better than 2 percent level. • 1550 nm wavelength mitigates bitumen fouling effects in oil sands tailing applications.