Ann: Quarterly Report - March 2018, page-69

Perhaps their deprecation is not fixed. Perhaps its also via units of production method.

If they are stockpiling, it's usually a sign that its not being sold as fast as they are produced.

No business wants to stockpile if there's a chance to make $$ out of it. Everyone would prefer $$ than to stockpile it unless there's some bottleneck issue in the mine to port or port to customer.

So what's the bottleneck issue?

Has some trucks broken down and need repairs? after all - depreciation is very big and those wear and tear eventually breaks down.

Or is it geopolitical issue of the trade war between US and China? (which resulting in lower demand for EVs? due to higher steel and aluminium costs?)