Online analysis of minerals from sulfide ore using near‐infrared Raman spectroscopy

• Published in: Journal of Raman spectroscopy 2020-06, Vol.51 (6), p.978-988
• Main Authors: Uusitalo, Sanna, Soudunsaari, Tuomas, Sumen, Juha, Haavisto, Olli, Kaartinen, Jani, Huuskonen, Jarmo, Tuikka, Aki, Rahkamaa‐Tolonen, Katariina, Paaso, Janne
• Format: Article
• Language: English
• Subjects: analysis; Bedrock; beneficiation; Flotation; Fluorescence; Infrared analysis; Internet; Iron; Levels; Liberation analysis; Low concentrations; Mine tailings; Minerals; online; Optimization; ore; Ores; Process parameters; Raman spectra; Raman spectroscopy; Spectroscopy; Spectrum analysis; Sulfide; Sulfides; Sulfur
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.5859

Efficient recovery of minerals from bedrock ore requires precise knowledge of the mineral levels during enrichment processes. Froth flotation is a commonly used method for efficient separation of different minerals from finely grinded sulfide ore. The mineral level information is an important tool for the optimization of flotation process parameters as it is uneconomical to make mineral products with unacceptably low concentrations and to lose a share of the valuable minerals of the ore to the tailings. Online mineral control is commonly executed with X‐ray fluorescence detection or laser‐induced breakdown spectroscopy, which detect the elements of the minerals during flotation. Unfortunately, in case of sulfide ores, the method suffers from inadequate detection of lightweight materials such as sulfur and the common nature of iron, as iron is constantly present in several different minerals found in sulfide ores. Raman spectroscopy can be used to detect the minerals instead of mere elements of ore. This paper presents the study of Raman spectroscopy for online detection of enriched sulfide ore minerals from froth flotation. The Raman instrument with a custom‐made probe connector allowed for the recording of good quality Raman spectra during froth flotation and for the identification and analysis of the valuable minerals levels. The comparison of Raman analysis to online X‐ray fluorescence and offline mineral liberation analysis show that Raman spectroscopy is a suitable method for the online analysis of sulfide ores. Volcanogenic massive sulfide ferrous iron ores containing sulfide minerals were analysed online using a near‐infrared Raman spectrometer at a Pyhäsalmi beneficiation facility. Raman spectra were used to identify different process phases and to detect enriched sulfide minerals chalcopyrite (copper), sphalerite (zinc), and pyrite (iron/sulfur). Results were compared to reference methods showing that Raman spectroscopy is a feasible online analysis tool for mineral level indication from finely grinded liquid‐immersed sulfide minerals containing light‐weighted or common elements.