Hertha Metals closes $133.65M Series A as iron plant breaks ground

Hertha Metals makes high-purity iron for rare-earth magnet manufacturers and is developing lower-carbon steel alloys for industrial customers. The Conroe, Texas, company closed a $133.65 million Series A to build its first commercial plant, then broke ground on the facility nine days later.

Its Flex-HERS system takes iron ore or waste oxides in forms including fines and lumps and feeds them through a semi-continuous, single-step reactor. Natural gas or hydrogen acts as the reductant, electricity powers the process and adjustments to the chemistry determine whether the output is iron or steel.

For magnet makers, the immediate question is purity. Hertha says its demonstration equipment has produced 99.95% iron, while trial quantities containing more than 99.9% iron are available. The company remained in active supplier qualification with major U.S. rare-earth magnet producers when construction began.

Khosla Ventures and Doerr Capital co-led the financing. The round includes a $65 million equity investment from the U.S. government through the Industrial Base Analysis and Sustainment program, working with the Economic Defense Unit. That federal portion is ownership capital, not a grant.

The material occupies a narrow but important part of the magnet supply chain. Hertha says neodymium-iron-boron magnets are roughly 70% high-purity iron by weight and estimates that China makes 94% of the high-purity iron used in them.

Chalyx has now broken ground beside Hertha’s pilot plant and is designed to make about 10,000 metric tons of steel-grade and magnet-grade high-purity iron annually. Hertha expects the roughly $100 million plant to come online in late 2027, followed by magnet-grade production in early 2028.