Hertha Metals’ Texas high‑purity iron plant: supply, process and capex notes for engineers
Reviewed by Tom Sullivan

First reported on MINING.com
30 Second Briefing
Hertha Metals will break ground this summer on a Conroe, Texas plant to produce 10,000 tonnes per year of high-purity iron for neodymium-iron-boron magnets, using its FLEXHERS (Flexible Fuel Hydrogen Electric Reduction Smelting) process that couples an electric arc furnace with natural gas or hydrogen. The startup already runs a one-tonne-per-day pilot using Minnesota ore and plans to scale to roughly 500,000 tonnes per year within four to five years, targeting both magnet and electrical steel markets. With 90% of current high-purity iron output in China and a US DoD ban on Chinese-origin rare earth magnets taking effect on 1 January 2027, the project directly targets a looming supply-chain gap.
Technical Brief
- FLEXHERS couples an electric arc furnace with either natural gas or hydrogen as reductant and energy source.
- Current Conroe pilot is a single-step steelmaking facility rated at one tonne per day throughput.
- Pilot plant is already selling limited volumes of product that meet specific customer high‑purity iron specs.
- Ore feedstock for the demonstration plant is sourced domestically from Minnesota iron ore operations.
- FLEXHERS is designed to process lower‑grade ores and iron ore fines that are uneconomic in blast furnaces.
- Process economics rely on replacing metallurgical coal with natural gas and electricity plus cheaper ore feed.
- Hertha has not disclosed project financing structure, fundraising schedule or any magnet/steel offtake contracts.
- DFARS changes effective 1 January 2027 will exclude Chinese‑origin rare earth magnets from covered defence systems.
Our Take
Rare earth and iron ore stories in our mining database are mostly dominated by majors like BHP, Rio Tinto and Vale, so a 2022-founded player such as Hertha Metals entering high‑purity iron for neodymium‑iron‑boron magnets signals that this niche is opening to smaller, process-focused entrants rather than just upstream miners.
With China currently accounting for about 90% of high‑purity iron and the DFARS ban on Chinese‑origin rare earth magnets kicking in from January 2027, US‑based capacity in Conroe, Texas positions Hertha Metals to compete for Pentagon‑linked and other defence supply chains that, in our coverage, have increasingly been looking to North American critical mineral sources.
The one‑tonne‑per‑day pilot plant in Texas and a four‑to‑five‑year ramp to roughly 500,000 t/y aligns with the project timelines seen in other critical mineral build‑outs in our sustainability‑tagged pieces, implying that permitting, grid connection and offtake structuring will need to be substantially advanced before the 2027 DFARS deadline to capture premium magnet demand.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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