The super large Valemax ships were built to reduce shipping costs for Brazil's Vale iron ore mining company, to allow Brazil to compete more effectively with Australian iron ore suppliers who are much closer to China and who therefore have lower shipping costs. China seeks to protect defend their own shipping businesses in the currently collapsed shipping industry, according to MercoPress's article "China bars Brazil's bulk carriers from its ports; clash over iron ore shipping rates", which I acknowledge. The irony is that the ships are being built in China contrary to Brazil's government's wishes.
Along with their decision to reduce rare earths exports, Mainland China appears to be making some interesting decisions, which might offer valuable insights into the motives of the Chinese Communist Party Central Committee.
This action would appear to benefit Australian iron ore suppliers: BHP Billiton Limited (NYSE: BHP, LSE: BLT, ASX: BHP); Rio Tinto Limited (LSE: RIO, ASX: RIO); and Fortescue Metals Group (ASX: FMG).
Also see the related Mineweb article: "Vale/China iron ore shp dispute deepens".