Iron Bridge taking FMG in a new mining direction
Located in WA’s world class Pilbara mining region, the Iron Bridge Project is a joint venture between Fortescue Metals Group (ASX: FMG) subsidiary FMG Magnetite and Formosa Steel IB, that will deliver high grade 67% Fe magnetite concentrate product.
Iron Bridge signifies Fortescue’s entry into the high-grade segment of the iron ore market, providing an enhanced product range while also increasing annual production and shipping capacity.
In May, Fortescue successfully made its first magnetite product, remarkably at first run grade of greater than 68% Fe.
The Australian Mining Review recently caught up with Fortescue Metals chief executive Dino Otranto for his first-hand view of the project and the achievements obtained at the project to date.
“Iron Bridge builds on Fortescue’s strong track record of safely and successfully developing and operating iron ore projects in the Pilbara and will lead the way for magnetite operations in Western Australia,” he said.
“Iron Bridge is Fortescue’s most complex iron ore project and once connected to the Pilbara Energy Connect program, will be Australia’s first magnetite project to operate using renewable energy by 2030.”
AMR: How are activities progressing at Iron Bridge? Iron Bridge transitioned to operational production in August. What is the next step in ramping up activities there?
DO: We have successfully completed technical commissioning, from the proof of concept to first production and shipment of high-grade magnetite.
We are now working to bring all the equipment up to capacity with staged mechanical commissioning.
We are on track to ramp up to capacity by August 2025, which will mark 24 months since we transitioned to operational production.
Our focus now is on completing the dry plant line B and the remainder of the wet plant.
AMR: This is Fortescue’s first magnetite operation. Is there much difference between commissioning and running a magnetite mine compared to your other iron ore projects?
DO: The Iron Bridge value chain is unique compared to our hematite operations and has a processing design that is different to every other magnetite producer.
The process, which is the subject of several patents, is designed to reduce energy consumption and water use.
It is primarily separate from existing Fortescue infrastructure but does interact at two key locations, receiving energy supply from the Solomon power station and loading product at Port Hedland by our Hedland operations team.
It also has dedicated water and energy requirements supplied from locations remote from the main mine site.
It’s important for the entire value chain to operate in harmony as there is a limited buffer or allowable separation of value chain steps.
The supply and management of water to our operations is a crucial element in the success of Iron Bridge as there is a complex water network that needs to be balanced.
Iron Bridge processing requires approximately 25GL per annum of fresh water when operating at full production with water being sourced from the Canning Basin, near mine borefields, recycled water from our concentrate handling facility (CHF) delivered through our return water pipeline as well as water extracted from the tailing storage facility.
Processing magnetite is significantly more intense than hematite which is why our processing plant design is a patented process and has been specifically designed to cost-effectively achieve high iron ore recovery while minimising energy and water usage.
The Iron Bridge ore processing facility (OPF) is physically larger and uses more plant and equipment than any of our hematite processing plants.
The most notable aspect of this design is the use of dry processing to achieve a very fine sized material.
To achieve 67% Fe product concentrate, the iron ore must be reduced from 400mm to 28 micron (0.028mm).
Unlike Fortescue’s haematite operations, Iron Bridge produces a wet concentrate product that is transported to Port Hedland through a 135km underground specialist slurry pipeline where dewatering and materials handling occurs at our CHF.
Magnetite concentrate also has a strict maximum transportable moisture limit to allow safe shipping of 9.5% which we achieve through dewatering the magnetite slurry at our CHF, creating very strict processing quality requirements on the CHF.
AMR: Have you incorporated any new technologies into developing and now operating Iron Bridge?
DO: A few of our most impressive technologies at Iron Bridge include: 12 high pressure grinding rolls with a total installed power of 93MW which reduce the 62.5 mtpa of OPF feed down to 80 micron; the high pressure grinding rolls operate in closed circuit with 12 massive air classifiers, which enable this classification down to 80 micron without introducing any water; and 10 high intensity grinding (HIG) mills, with a total installed power of 50MW.
These vertical stirred mills provide size reduction down to 35 micron in open circuit with high efficiency.
AMR: Fortescue has a strong push towards shrinking its environmental footprint. Is there anything we can highlight in that regard?
DO: Iron Bridge will be among our first fossil fuel-free sites once we connect it up to Pilbara renewable energy through our Pilbara Energy Connect program.
Additionally, the process flow has unique design elements throughout it to reduce electrical power and water usage.
Electrical power is reduced by the extensive use of dry grinding using high pressure grinding rolls.
We reduce the product size down to 80 micron while it remains dry by using two stages of high pressure grinding rolls and air classification.
This uses less power than traditional comminution pathways such as SAG and Ball Milling as well as reducing water usage.
Water usage is further reduced due to the 10 Lyons Flow Control Unit (LFCU’s) utilised to deslime the concentrate in the wet processing plant.
Facts and figures
Iron Bridge is expected to produce 22mtpa of high-grade magnetite concentrate over its lifetime.
More than 20,000 jobs have been created through the Iron Bridge project with the site workforce peaking at 4,000 jobs during construction.
Another 900 full time jobs will be created with the project moving into operations.
A total of $3.6b in goods and services have been sourced within WA for the Iron Bridge project and operations, including over $331m awarded directly to local Traditional Custodian Nyamal businesses since 2020.
