Autosime you are confusing cash costs with fixed costs (i.e. the...

Autosime you are confusing cash costs with fixed costs (i.e. the head office + interest payments). Note that these HO + Int payments are obviously paid in cash but its normally done at the corporate level not at the operating plant level.

Cash costs of production are most relevant in calculating the cash contribution per tonne of iron ore sold.

Depreciation once capex has been spent is largely irrelevant once the plant is up and running (well if you want to get technical you may argue that the depreciation could be relevant insofar as it is a proxy for ongoing maintenance capex - but I am not sure this will be the case for GBG in the first few years of the plant)