Pyrrhotite oxidation and its influence on alkaline amine flotation. (February 2015)

• Record Type: Journal Article
• Authors: Bunkholt, Ingjerd; Kleiv, Rolf Arne
• Is Part Of: Minerals engineering. Volume 71(2015)
• Page Start: 65
• Page End: 72
• Publication Date: 2015-02
• Subjects: Mineral processing -- Ground calcium carbonate -- Flotation -- Amine -- Pyrrhotite -- Oxidation; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2014.10.019
• Languages: English
• ISSNs: 0892-6875

Abstract

Highlights: Flotation recoveries of pyrrhotite are highly dependent on air exposure time. Microflotation recoveries dropped with exposure for more than 5 min at pH 8. At higher pH, recoveries were low at all exposure times tested. Bench scale flotation recoveries confirmed the dependency of exposure time. Abstract: In the production of ground calcium carbonate (GCC) for the paper industry, pyrrhotite dramatically reduces the GCC brightness and the removal of pyrrhotite through froth flotation is essential. The present study aims to study the effect of pyrrhotite oxidation on flotation recoveries during typical GCC flotation (i.e. alkaline pH, CaCO3 saturation, amine collector). EDTA extraction and measurements of Eh (redox potential) showed a significant difference in pyrrhotite surface oxidation state when comparing exposure times of 40 and 60 min, the latter being significantly more oxidised. Microflotation results show that when pyrrhotite is exposed to air extending for more than 5 min at pH 8, the recoveries drop significantly. At higher pH, recoveries were generally low at all exposure times tested. Flotation recoveries showed strong correlation with zeta potential measurements. Bench scale flotation experiments on a sulphide bearing marble, confirmed that pyrrhotite oxidation significantly lower the GCC quality at low collector concentrations. By increasing the amine concentration, the flotation performance became independent of pH and exposure time.