For anyone interested in this type of trade, there is a website game called ‘entreprenauts’ in which various players operate shipping and storage companies, in addition to the mining and factory companies which need things shipped.

It usually turns out that buying raw materials is the easy part compared to finding someone with free space on a (container, dry bulk, liquid bulk, compressed gas) ship that will be traveling between the ports you need - and then you will be bidding against other people who need that cargo space