Application of Near Infrared Sensors to Minerals Preconcentration
Thesis or dissertation
University of Exeter
Thesis contain a detailed characterization of the mineralogy and geochemistry of ore from Anglo American mines. Hence, in view of Anglo American stated intention to sell the South American mines, all information regarding the ore and its processing characteristics is considered to be commercially sensitive and as a result, is being locked down.
Reason for embargo
The aim of this project was to investigate the potential and suitability of the application of near Infrared spectroscopy/sensors in automatic preconcentration of complex ores. Two ore types (copper and platinum) were considered for investigation. The near infrared region of electromagnetic spectrum has been used for mineral mapping in the minerals industries. However, its application as a sensing technology in the sorting of base and precious metals is still minimal. In practice, a near infrared sensor can measure characteristic features of carbonate, hydroxyl and water groups contained in minerals and rocks. Successful sensor-based sorting requires a good understanding of the minerals and their distribution in an ore. For the copper ores, mineralogical analysis was carried out using QEMSCAN® and qualitative XRD analysis. XRF analysis was used to determine the copper concentration in the various particles. In addition to the XRF elemental analysis, copper values were calculated from copper bearing minerals in the ore. XRD analysis was performed on the platinum ore. Methods of ore sorting based on near infrared readings and near infrared active functional groups (-OH, H2O, and CO32-) were investigated and strategies developed for both ore types. In addition to external environmental influence, most minerals contain water in their chemical structure. Therefore, considering the H2O absorption feature(s) for ore sorting was not considered optimal. Strategies were developed which target the discrimination of either or both carbonate and hydroxyl bearing particles as waste. Individual particles spectra were analysed and absorption features assigned to the various chemical species and minerals responsible for the absorptions. Due to individual particle mineralogical variation, particles were classified either as products, waste or middlings. For copper ore, targeting only the calcite (carbonate) dominated particles for discrimination as waste provided a better option for preconcentration. Application for the platinum ores targeted the discrimination of chlorite, antigorite, and/or calcite dominated samples as waste. Compared with sample mineralogy, samples could be classified as product or waste using near infrared.
Nigerian Tertiary Education Trust Fund (TETFUND) and Anglo American
Iyakwari, S., Glass, H. J., 2014, ‘Influence of mineral particle size and choice of suitable parameters for ore sorting using near infrared sensors’. Miner Eng, 69, 102-106
Iyakwari, S., Glass, H. J., Kowalczuk, P. B., 2013, ‘Potential for near infrared sensor-based sorting of hydrothermally-formed minerals’. J Near Infrared Spectrosc, 21(3), 223-229
Iyakwari, S., & Glass, H. J., 2015. Mineral preconcentration using near infrared sensor-based sorting Physicochemical Problems of Mineral Processing 51(2), in press
Iyakwari, S., & Glass, H.J., 2014b. Strategy for copper preconcentration using near infrared sensor-based sorting. Proceedings of the Mineral Engineering Conference (MEC 2014), eds. M. Lutynski, T. Suponik, Istebna (2014) 288 – 296
Glass, Hylke. J.
PhD in Mining and Minerals Engineering