Afaik, those types of ships are typically referred to as bulk carriers
A bulk carrier or bulker is a merchant ship specially designed to transport unpackaged bulk cargo — such as grains, coal, ore, steel coils, and cement — in its cargo holds.
The interesting element is the extra option that COSCO gains by being able to leverage one extra type of ship. This method is probably inferior cost-wise to regular containers, but if a bulk carrier is the only ship that happens to be available, then, it becomes very valuable to have the option.
Afaik, those types of ships are typically referred to as bulk carriers
From https://en.wikipedia.org/wiki/Bulk_carrier
The interesting element is the extra option that COSCO gains by being able to leverage one extra type of ship. This method is probably inferior cost-wise to regular containers, but if a bulk carrier is the only ship that happens to be available, then, it becomes very valuable to have the option.