Metallurgy
Haematite
The haematite ore at Argyle is relatively hard. Low grade ore and clays are less dense and considerably softer that the haematite. When the various materials are subject to crushing and screening. The "clay material" breaks down into finer particles. The fine particles can be removed by a combination of dry and wet screening. With the removal of the clays, the final product is beneficiated.
Preliminary metallurgical test work has indicated that the Argyle Iron Ore can be beneficiated but additional work is required to provide sufficent data to design the final crushing and screening circuit.
Magnetite
In addition to haematite, RMC has magnetite ore underlying the haematite resource. Whilst a JORC compliant resource has not been prepared for this material, the magnetite ore is of interest.
The magnetite occurence was identified as part of the Haematite exploration program. Subsequent aeromagntic survey has clearly outlined future magnetite exploration targets. Whilst the ultimate size and grade of the magnetite resource is unknown, it is estimated that the resource has development potential.
To provide a saleable product, the magnetite ore requires crushing / screening / fine grinding / wet processing / magnetic separation / filtering, drying etc. The final product is a high Fe material, (+65% Fe), of fine size, (<45 micron) which requires special handling in transport and shipping.
Preliminary test work using Davis Tube has shown that the RMC magnetite can produce a concentrate with an Fe content >66.5% Fe with weight recoveries exceeding 53%, at an average grind size of 32 microns.
RMC does not have a magnetite resource sufficiently large to support the type of development being contemplated by other companies such as: Grange Resources, Gindalbie Metals etc. Instead, RMC is considering the production of a “partial concentrate” by crushing and screening the magnetite ore to 2 to 3 mm in size, passing over a magnetic separator to theoretically upgrade the average +40% Fe magnetite to a +50% Fe partial concentrate.
There is a market in China for the provision of raw magnetite feed to concentrate plants. (Shougang imports a raw magnetite feed from Peru for processing in beneficiation plants in Hebei and Zhejiang Provinces). The challenge for RMC is to demonstrate the economics of such a proposal.
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