RE: DRI testwork29 Mar 2025 08:14
DRI testwork.
I've continued to work on the Chinese tech. flowsheet, rotating ChatGPT into GROK with some refinements and conditionality. Note we have: Chinese tech. for hematite, DRI grade, and much reduced and, critically, dry tailings.
Here's the output:
ZIOC aims to beneficiate its Zanaga hematite (30-38% Fe) to DRI-grade (≥67.5% Fe) using proprietary Chinese technology, emphasizing reduced wet tailings management. Wet tailings pose environmental and cost challenges, especially at Zanaga’s remote site in the Republic of Congo, so a dry process is key. The ore, a fine-grained banded hematite quartzite (BHQ), requires efficient liberation and concentration to meet DRI purity needs (low silica, alumina, phosphorus).
LIKELY TECHNOLOGY: FLUIDIZED BED ROASTING + MAGNETIC SEPARATION
Two Chinese innovations fit: High-Pressure Grinding Rolls (HPGR) + advanced magnetic separation and Fluidized Bed Roasting + magnetic separation. With tailings reduction critical, the latter stands out.
Process Flowsheet
Ore Prep: BHQ ore is crushed, possibly with HPGR, to liberate hematite—dry process.
Roasting: Ore enters a fluidized bed reactor (500-800°C) with a reducing agent (e.g., coal), converting hematite to magnetite. Dry step with off-gas management.
Magnetic Separation: Magnetite-rich ore undergoes dry low-intensity magnetic separation (LIMS), yielding 67.5% Fe+ concentrate and dry gangue.
Concentrate: Dry product is pelletized for DRI or slurried minimally for pipeline transport.
Tailings: Dry gangue is stockpiled, avoiding wet tailings.
WHY IT FITS
Tailings: Dry from start to finish, eliminating wet tailings—ZIOC’s priority. Gangue can be repurposed (e.g., aggregate).
Grade: Roasting enables 67-69% Fe with low impurities, proven for fine hematite, meeting DRI needs.
Chinese Edge: Proprietary fluidized bed designs (e.g., efficient reactors, heat recovery) enhance cost-effectiveness.
Zanaga: Suits BHQ, supports low-cost goals, and integrates with slurry pipeline plans.
HPGR + Magnetic Alone
HPGR liberates hematite, followed by dry magnetic separation (HGMS/RERMS). It avoids tailings but struggles to hit 67.5% Fe due to hematite’s weak magnetism, requiring roasting for DR-grade.
Why Roasting Wins
HPGR aids liberation but can’t standalone. Roasting transforms hematite to magnetite, ensuring high-grade output. China’s optimized roasting systems likely make it the proprietary tech, possibly with HPGR as a booster.
IMPLICATIONS
THIS DELIVERS A PREMIUM DRI PRODUCT WITH MINIMAL TAILINGS COSTS, LEVERAGING CHINESE INNOVATION FOR EFFICIENCY. LIKELY TIED TO A SPECIFIC REACTOR DESIGN, IT ALIGNS WITH ZIOC’S STRATEGY.
CONCLUSION
FLUIDIZED BED ROASTING + MAGNETIC SEPARATION, OPTIONALLY WITH HPGR, IS THE PROBABLE TECH. IT HITS 67.5% FE+ AND ELIMINATES WET TAILINGS, FITTING ZANAGA’S NEEDS AND CHINESE EXPERTISE.