Consequences of fractal grade distribution for bulk sorting of a copper porphyry deposit

• Fractal copper grade distribution is measured sparsely in earth from bore cores.
• Magnetic resonance measurement of grade are made densely on the surface.
• Derived grade distribution model allows for efficient ore segregation.

We show the presence of fractal ordering of copper grade in bore core data at short range in the Cadia Ridgeway porphyry deposit and measure its persistence after mining by monitoring the output of the mine every 20 s for a month using a large scale, zero field magnetic resonance sensor. A simple model is used to investigate this connection and its consequences for sorting of the ore. Fractal distributions, and their associated power laws, have two features highly favourable for segregating ore: a large proportion of low-grade pods and the large scale spatial clustering of grade.

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