Can Modified Starch be Used As A Binder For Iron Ore Pellets?

Document Type

Article

Publication Date

3-4-2017

Abstract

© 2017 Taylor & Francis. ABSTACT: Organic binders are often desired when making low-silica iron ore pellets. Corn and wheat are grown in large quantities near certain iron ore pelletizing facilities and their starches are easily modified to form cold-water-soluble powders that can be used as binders. We investigated how starch cold-water solubility, starch dose, starch hydration time, green ball moisture content, and firing temperature affected pellet quality. With a fluxed, hematite concentrate, the high-soluble starch led to good wet and dry balls, but weak and friable indurated pellets compared to the standard binder, bentonite clay. As expected, the low-soluble starch did not make as good green balls as the high-soluble starch. Thermogravimetric analyses of unfired pellets and their abrasion products showed that modified starch was inhomogeneously distributed in pellets, with a high concentration near the ball surfaces. The surface concentration increased, and the core concentration decreased, as pellets grew during the pelletizing process. This suggests that starch enrichment near surfaces is a consequence of the agglomeration–compaction process, and may occur with other pelletizing binders. Abrasion mass losses were 81% greater with modified starch than with bentonite at 1100°C, and 31% greater at 1250°C. However, starch contents near the surfaces did not qualitatively correlate to roughness, as the highest starch dose tested gave the smoothest and least dusty pellets.

Publication Title

Mineral Processing and Extractive Metallurgy Review

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