South Flank is a sustaining mine replacing BHP's Yandi 80Mtpa Yandi operation, which is largely played out.

According to BHP it will be the most technically advanced high quality iron ore mine in WA and, with the existing Mining Area C, form the world's largest operating iron ore hub. Together the two operations will turn out 145Mtpa.

It has expanded the existing infrastructure at Mining Area C, which involved building an 80Mtpa crushing and screening plant, an overland conveyor system, and stockyard and train loading facilities.

BHP also had to buy additional mining fleet and conduct substantial mine development and pre-strip work.

The mine was designed with autonomous haulage in mind.

South Flank has a capital intensity of US$45 per tonne, about half that of BHP's most recent major iron ore project Jimblebar.

More than A$4.6 billion of works were awarded for South Flank with 78% awarded to Australian businesses, including 41% to WA businesses and 37% committed in the Pilbara.

It is the second of the big three iron ore sustaining projects to begin operating after Fortescue Metals Group's US$1.27 billion, 30Mtpa Eliwana project, which hit the first ore milestone last year.

Rio Tinto's US$2.6 billion 43Mtpa Gudai-Darri mine is expected to begin its production ramp up in early 2022.

Those three projects have all managed to avoid the cost blowouts WA's labour shortage is dealing to projects. FMG's Iron Bridge magnetite project is a case in point.

BHP Minerals president Edgar Basto said South Flank was the largest iron ore mine to start operating in Australia in more than 50 years and was on time and on budget.

"South Flank's high quality ore will increase [BHP] WA Iron Ore's average iron ore grade from 61% to 62% and the overall proportion of lump from 25% to 30-33%," he said.

"The project has created more than 9000 direct and indirect jobs during construction and will provide more than 600 operational roles through its life.

"South Flank's ore will supply global steel markets for the next 25 years, helping to build electricity, transport and urban infrastructure across the globe. And its high quality ore will have an important role in helping BHP's customers lower their greenhouse gas emissions.

"South Flank is on Banjima country and this milestone would not have been possible without their support and collaboration over many years. We are proud of our longstanding partnership and strong working relationship with the Banjima people and we thank them for their vital contribution to this success.

"First ore from South Flank is the result of the hard work and ingenuity of people and organisations spanning state and federal governments, our suppliers, customers and partners in WA and around the world."

The relationship with the Banjima needed some tweaking over the past year.

At the height of the crisis caused by Rio Tinto's destruction of two 46,000 year old rock shelters in the Juukan Gorge last year, BHP created a heritage advisory committee with the Banjima. It also promised them that it would not destroy any culturally significant sites without consulting with them first.

Chamber of Minerals and Energy of WA chief executive Paul Everingham said South Flank provided a glimpse of the future of mining and insights into best practice in the sector.

"South Flank showcases many aspects of best practice, which not only BHP but CME member companies around the state strive to achieve on a daily basis," Everingham said.

"The diversity of the South Flank workforce with 40% female and 15% Indigenous operational staff reflects the nature of modern mining workforces.

"It is also extremely pleasing to see the positive relationship BHP has forged with the Banjima people and the more than $1.5 billion in works at South Flank that have been awarded to Pilbara businesses."

Everingham said South Flank also highlighted the sector's commitment to working safer, cleaner and smarter.

"The modular construction methods used at South Flank reduced exposure to some of the higher risk construction activities that would traditionally have been involved in a major project like this.

"South Flank has also been designed from the start with a focus on technology and the use of autonomous mining equipment, including haul trucks."