A Study of Rock Magnetism of High-Grade Hematite Ores

Abstract

Rock magnetism is useful in various applications. Hematite is one of the two most important carriers of magnetism in the natural world and its magnetic features were mostly studied through laboratory experiments using synthetic hematite samples. A gap exists between the magnetic behaviors of hematite contained in the natural rocks and ores and those of synthetic hematite samples. This paper presents the results of a rock magnetism study on the natural hematite ores from the Whaleback mine in the Hamersley Province in the northwest of Western Australia. It was found that high-grade hematite ores carry a much higher remanent magnetization than induced magnetization. Hematite ores with less than 0.1% magnetite appear to have an exponential correlation between the bulk susceptibility and hematite content in weight percentage, different from the commonly accepted linear relationship between the bulk susceptibility and hematite content obtained from synthetic hematite samples. The new knowledge gained from this study contributes to a better understanding of magnetic behaviors of hematite, particularly natural hematite, and hence applications to other relevant disciplines.

Magnetic Mineralogical Characteristics of Hamersley Iron Ores in Western Australia

“…The province contains extensive banded iron formations (BIFs) and large iron-ore deposits, consisting predominantly of hematite/martite and goethite, and contains approximately 10% of the world's known reserves of iron ore [1]. Study on magnetism of iron ores and rocks in this region has a profound impact on exploration of new iron ore deposits [2] [3], understanding the genesis of iron ore formation [4]- [6], magnetic mineralogy [7]- [9], and potentially iron ore grade control in mining [10].…”