Effect of dissolved metal sulphates on gas-liquid oxygen transfer in agitated quartz and pyrite slurries

• Published in: Minerals engineering Vol. 13; no. 14; pp. 1555 - 1564
• Main Authors: Zuidervaart, E, Reuter, M.A, Heerema, R.H, Van Der Lans, R.G.J.M, Derksen, J.J
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.12.2000; Elsevier Science
• Subjects: Applied sciences; biooxidation; Exact sciences and technology; gold ores; Hydrometallurgy; Metals. Metallurgy; oxidation; Production of metals; Production of non ferrous metals. Process materials; Sulphide ores; oxidation; Sulphide ores; gold ores; biooxidation; Gold ore; Pyrite; Biochemical reaction; Ore treatment; Oxidation; Experimental study; Hydrometallurgy; Sulfide ore
• ISSN: 0892-6875; 1872-9444
• DOI: 10.1016/S0892-6875(00)00138-2

A previous study on mass transfer in agitated three phase systems showed that for quartz slurries the volumetric oxygen transfer coefficient k La [s −1] decreases with increasing solids fraction, whereas pyrite particles increase the k La value. The present study was conducted in continuation of these results and attempts to explain why the addition of pyrite particles resulted in an increase in k La. For this purpose, the effect of ionic strength, mineral density and oxygen consumption due to homogeneous reactions was examined. Neither the high density of pyrite nor the oxygen consumption could offer an explanation for the increased k La values obtained for pyrite slurries. The variable mineral density did not affect k La at all, while the consumption of oxygen was not large enough to cause an enhancement of k La. However, by reducing bubble coalescence frequency and thus bubble size, the ionic strengths found for pyrite slurries could partially explain the increase in k La. For 15 vol.% pyrite slurries, the ionic strengths proved to account for at least 60% of the enhancement. The variable(s) and/or mechanism(s) causing the remaining 40% of the enhancement could not be identified (yet). To demonstrate the effect of ionic strength as such, various electrolytes (viz. CuSO 4, FeSO 4, ZnSO 4 and Al 2(SO 4) 3) were added to a 15 vol.% quartz slurry. For all metal sulphates, increasing the ionic strength up to about 0.25 mol/l resulted in an increase of k La by up to a factor 2.5.