IngentaConnect WATER CHEMISTRY EFFECTS IN IRON ORE CONCENTRATE AGGLOMERATION FEE...

Authors: Eisele, T. C.¹; Kawatra, S. K.¹; Ripke, S. J.²

Source: Mineral Processing and Extractive Metallurgy Review, Volume 26, Numbers 3-4, -4/July-September 2005 , pp. 295-305(11)

Publisher: Taylor and Francis Ltd

Abstract:

In two different iron ore processing plants, it was demonstrated that when magnetite concentrate was filtered to prepare it for use as pelletization feed, the moisture that remained in the filter cake had greatly elevated levels of cations compared to the water removed by the filtration process. In particular, calcium concentrations in the filter cake were 565 times higher than in the filtrate water in Plant 1 and 19.4 times higher than the filtrate water in Plant 2. This effect is due to the adsorption of divalent cations on the magnetite surfaces resulting from electrostatic attraction when the pH of the solution is in the range where magnetite has a negative Zeta potential. Measurements of the Zeta potential as a function of pH for magnetite from Plant 2 determined that its point of zero charge (PZC) occurred at pH 3.0 to 3.5, which was much lower than is commonly reported in the literature and demonstrates that the PZC for magnetite is much more variable than is commonly thought. Plant experiments were carried out using carbon dioxide to reduce the pH of filter slurry so that the PZC could be approached. This was intended to allow adsorbed cations to be released from the magnetite surfaces during filtration. The pH adjustment was demonstrated to improve filtration rates by as much as 23%.

Keywords: cation adsorption; Zeta potential; filtration; calcium; iron ore; surface chemistry

Document Type: Research article

DOI: 10.1080/08827500590944063

Affiliations: 1: Department of Chemical Engineering, Michigan Technological University, Houghton, Michigan, USA 2: Cliffs Mining Company, Wabush Mines, Wabush, Labrador, Newfoundland, Canada

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WATER CHEMISTRY EFFECTS IN IRON ORE CONCENTRATE AGGLOMERATION FEED