Magnetic Mineralogical Characteristics of Hamersley Iron Ores in Western Australia

William W Guo

doi:10.4236/jamp.2015.32023

Abstract

This paper presents the research outcomes of a magnetic mineralogical study on Hamersley iron ores. Thermal magnetic analysis shows that typical high-grade martite-microplaty hematite or M- (mpl H) and martite-microplaty hematite-goethite or M-(mpl H)-g ores contain a small amount of original magnetite. A small amount of magnetite/maghemite and pyrite/pyrrhotite/siderite may exist in typical martite-goethite (M-G) and martite-ochreous goethite (M-oG) ores. In “the hardcap zone”, M-(H)-g ores contain a small amount of magnetite and maghemite. Compared with XRD, thermal magnetic analysis is not only more sensitive in identifying trace of magnetite contained in high-grade hematite ores, but also more diagnostic in identifying other unstable magnetic minerals like maghemite and pyrite/pyrrhotite/siderite co-existed in the ores.

Highlights

The Hamersley Province in the southern Pilbara is situated in the northwest of Western Australia, approximately 1000 km north of Perth
This paper presents the research outcomes of a magnetic mineralogical investigation on Hamersley iron ores
It is noticeable that iron sulphides such as pyrite and pyrrhotite are present in some of the ores, goethite-rich ores. This thermal magnetic analysis indicates that a trace or a small amount of original magnetite exists commonly in typical high-grade martite-microplaty hematite or M-(mpl H) ores and martite-microplaty hematite-goethite or M-(mpl H)-g ores in the Hamersley Province

Summary

Introduction

The Hamersley Province in the southern Pilbara is situated in the northwest of Western Australia, approximately 1000 km north of Perth. This paper presents the research outcomes of a magnetic mineralogical investigation on Hamersley iron ores This is the first time that a systematic thermal magnetic approach was used to identify magnetic mineral combinations of different iron ores in the region. Compared with other methods such as XRD, this approach was proven more sensitive to trace of magnetite contained in high-grade hematite ores, and more diagnostic in identifying other unstable magnetic minerals co-existed in the ores. This new finding leads to a better understanding of Hamersley iron ores classification established through traditional geological, geochemical, and mineralogical models [14]-[16]. Conclusions will be drawn from this study at the end of this paper

Classification of Hamersley Iron Ores

Principles of Thermal Magnetic Analysis

Discussion

Findings

Contribution to Hamersley Iron Ore Classification

Conclusions