Arrium was an Australian mining and materials company, employing nearly 10,000 workers before going into voluntary administration in 2016 with debts of more than $2 billion.

In 2006, an agreement was announced under which OneSteel would buy out scrap metal company Smorgon Steel for US$1.2 billion.

[7] In the same year, OneSteel sold its Piping Systems business and associated property investments to US-based McJunkin Red Man Holding for a total of $100 million.

In October 2012, a new dual gauge railway balloon loop was commissioned at Whyalla with the purpose of increasing Arrium's iron ore export capacity to 12 million tonnes per annum.

[24] In October 2015, the company announced that it was working with the South Australian government to facilitate third party use of the Whyalla harbour to make use of its excess capacity.