Hawsons Iron (ASX:HIO) has validated and de-risked the phase one mineral processing design developed by global engineering firm Stantec for its Hawsons Iron Project.
The validation comes from a pilot testwork program emanating from a strategic review at the project, situated 60km southwest of Broken Hill in New South Wales in the emerging Braemar Iron Province.
It is potentially capable of producing the world’s ‘highest‐grade’ iron product (70% Fe), making it among the world’s leading undeveloped high‐quality iron ore concentrate and pellet feed projects, the company says.
Executive Chairman Bryan Granzien notes the pilot test work program – recently undertaken at the ALS metallurgy laboratory in Perth – had validated the effectiveness of the new design and found comminution energy usage was up to 30% below Stantec’s theoretical estimates.
Granzien notes Hawsons has essentially implemented the three-pronged strategic review action plan adopted in February 2023 to strengthen the business case for developing the project.
“We will now finalise a comprehensive project investor information memorandum in October 2023 to support imminent discussions with potential strategic partners prepared to help fund the modified (Bankable Feasibility Study) BFS.”
Granzien adds that a modified BFS could be completed within 12 months after securing the required funding.
He says the pilot testwork program has de-risked Stantec’s proposed phase one flowsheet design as a viable technical solution which can now be progressed to support a modified BFS for an 11 million tonne per annum project.
“Importantly, this proof-of-concept program has also provided valuable data to enable Stantec to improve their flowsheets to potentially reduce capital and operating costs further and revise the process required to generate potential secondary waste stream ore-sand products.”
Stantec’s design aimed to reduce capital and operating costs by paring the number of processing steps involved; lowering power and water use; eliminating grinding media; trimming downstream equipment sizing; and improving tailings management.
An initial pilot scale testwork program was recommended to confirm the performance and economic benefits of the redesigned processing circuit, which involves a unique configuration of mature and proven technology.
The Executive Chairman says the positive results had enabled Stantec to further amend the phase one flowsheet, subject to undertaking recommended follow-up pilot testwork programs which would also support refinement of the more traditional phase two magnetite recovery circuit.
He says these additional pilot testwork programs to support further refinement of the final flowsheet designs can be undertaken as part of an ongoing scope of work once activity on a modified BFS gets underway.
Stantec’s design concept was originally based on two 5.5Mtpa processing trains, each using 2 high-pressure grinding rolls (HPGR) fed by primary crushers, with a +100mm sizing screen prior to the HPGRs.
Hawsons Iron notes this oversized screened material would be stockpiled and fed into a pebble mill as a grinding medium downstream of the HPGRs, set up in series and choke-fed by surge bins.
The testwork found that the coarse rock (pebbles) ground away in the primary pebble mill at a faster rate than anticipated and that a higher pebble feed-rate than the theoretical estimate would be required to maintain the pebble mill load. Due to the faster-than-anticipated grinding performance, Stantec now considers only 2 front end HPGR units to be necessary, in conjunction with a reduction in oversized screened material to +70mm to maintain the pebble mill load.
The revised flowsheet also includes a smaller third HPGR unit operating in a re-crush application with a circulating load reporting to either the primary pebble or secondary milling circuit.
Within the original proof-of-concept flowsheet -15mm to +1 material was expected to be rejected as barren waste. The test work indicated that this potential waste stream of predominantly -8mm to +1 material was magnetic and still graded 11% Fe.
Consequently, this stream will require additional processing to liberate and recover the contained magnetite, subject to determination of the final process design.
Write to Adam Orlando at Mining.com.au
Images: Hawsons Iron
