hematite, page-68

What sriked me in the recent BRM ann was that the ore grades were indicated as Calcined Fe (CaFe) calculated by the formula CaFe% = ( (Fe%) / (100 – LOI1000) ) * 100

Has anybody seen any LOI values in recent UMC announcements?

Here are some grade of rock chip samples:
SF004RC S Flank Marra Mamba 58.3%FE 9.83 LOI
SF009RC S Flank Marra Mamba 64.7%FE 2.76 LOI

If you calculate the CaFE% of the 2 samples above you get:
64.65% for SF004RC
66.53% for SF009RC

wow!

Loss on Ignition (LOI)

Whilst it is desirable to have low contaminant levels of the elements mentioned above, it is considered the opposite for an LOI measure. Essentially, the LOI is a measure of the water content of the ore, which evaporates when the ore is fed into a blast furnace.
A typical iron ore analysis should include an LOI determination at 1000ºC, normally undertaken by Thermogravimetric Analyser (TGA). This allows for an addition of the oxides, generated at the ignition temperature and the LOI, to arrive at a total (oxides plus LOI). The LOI is due to the loss of water from hydrated minerals (goethite, gibbsite and kaolinite), decomposition of carbonates (calcite, siderite and dolomite) and the volatilisation of organic compounds. The LOI may be offset to some extent by the weight gain due to oxidation of reduced iron and manganese mineral phases.