I accept there are substantial areas with grades over .03% but they seem to be indespersed with lower grades. Mining 18Mt p.a would require an area of 1 sq Km to a depth of 10m every year, which doesn't sound like much when you have 2000Km2 of allevial flats but would tend to average the grade somewhat.
18,000,000 t x .03% = 5400 t x 70% recovery = 3780 t Treo