The South32 is a result of the breakup of BHP Billiton company in two. This company will have in its portfolio those assets considered non-priority by BHP. It will be called South32 because most of its mines are located in the southern hemisphere along the latitude 32 in Australia and South Africa.
This is the new market trend and BHP as well as VALE SA will be selling these new substantial parts of the new companies in IPOs on the stock exchanges. A way to improve valuation, raise new funds, wipe the company to avoid contamination of good assets and refocus the assets of interest.
The new company will bring together the manganese mines, aluminum and nickel, with copper and coal assets of less interest (Source: http://www.geologo.com.br).