"I would have thought the amount mined is completely different to what is milled given that ore has to be transported, crushed, grinded, leached etc etc. i.e. there is a delay of some time between mining and milling. I've read that leaching can take between 1-2 months - I've got no idea how it works at Mt Magnet other than to say I think there would be some sort of time delay."
Sam for me that paragraph you posted was talking about mill reconciled product, ie the relationship between tonnage and grade in (expected ounces) and ounces out (produced ounces). As I said it was very confusing and my previous post is my best guess at what it meant, maybe someone else can give an opinion.
With regard to leaching you might be getting confused between heap leaching and conventional cyanide leaching which happens over periods of hours/days (not months) depending on how large and exposed the gold particles are to the cyanide solution.
"The surface of a gold particle will typically be dissolved at a rate of around 0.2-0.5 µm of surface depth per hour in a cyanide leach. For large gold particles and nuggets, this is too slow to be fully dissolved in a typical processing plant. Much simpler and less expensive gravity methods are available to recover this gold. Cyanidation is used for gold that is distributed finely through a mineral matrix."
If you want to go really deep into the science you can read this below (from where I extracted the chart below) which shows an example of the effect of adding oxygen to the cyanide solution and how the % gold extracted changes over time. Heap leaching on the other had, which is a completely different process, can take one or two months for simple gold oxide ores or even years for other ore types, like nickel laterite ores. I don't think RMS are currently doing any heap leach processing of their ores. Esh
(20min delay)