Hydrofluoric acid: Production route
Fluorspar kilns, and a new route from phosphate waste
What this tab covers How it is made: the main production routes or, for product families, the main product types and technologies, compared on share of supply, inputs per tonne, plant scale, yield, co-products and unit cost.Virtually all HF comes from acid-grade fluorspar reacted with sulphuric acid. Plants differ in kiln design, pre-reactors and the degree of purification. A second route recovers fluorine from fluorosilicic acid (FSA), a by-product of phosphoric acid plants, which is growing in China and the US. Small volumes come from depleted uranium hexafluoride deconversion. Electronic-grade HF is a purification step on top of AHF, sold in a separate, higher-priced market.
Routes compared
| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| Fluorspar plus sulphuric acid in rotary kilns | over 90% of world HF (indicative) | about 2.1-2.2 t acidspar (97% CaF2) and 2.6-2.7 t H2SO4 (100%) per t HF; fuel for kiln heating (indicative; stoichiometric 1.95 t CaF2 and 2.45 t H2SO4) | typical plants 20-60 kt/yr; Navin Dahej 40 kt/yr, Surat about 20 kt/yr | about 90-95% on fluorine (indicative) | anhydrite about 3.4-3.6 t per t HF | fluorspar about $1,000/t HF at the 2025 US import value of $470/t; acid about $260/t HF at $100/t, $1,000/t at $400/t (2026) (indicative) |
| Fluorosilicic acid (FSA) route | small but growing (indicative) | FSA from phosphate processing; US recovered 45 kt FSA in 2025, equivalent to about 73 kt of fluorspar (USGS) | 10-50 kt/yr (indicative) | not published | silica | lower feedstock cost than fluorspar where FSA is available (indicative) |
| By-product HF from uranium deconversion | very small | depleted UF6 stocks | small | not published | uranium oxide | not published |
| Electronic-grade HF purification | a few percent of HF by volume, much more by value (indicative) | AHF plus ultra-pure water | 5-30 kt/yr (indicative) | not published | off-spec acid sold to industrial grades | several times AHF price (indicative) |
How each route works
Fluorspar plus sulphuric acid in rotary kilnsDried acidspar and oleum-fortified acid are mixed in a pre-reactor and fed to an externally heated kiln. HF leaves as a gas and is cleaned, condensed and distilled. The anhydrite residue is neutralised with lime. Licensors include Buss ChemTech; most Chinese, Mexican, Indian and Western plants use this route.
Proven and flexible; tied to fluorspar supply and sulphuric acid prices.
Fluorspar tile (USGS; Clarke and Huxtable); ChemIn Digest (Feb 2026) Fluorosilicic acid (FSA) routeFSA captured from phosphoric acid evaporators is converted to HF, either directly with sulphuric acid or via silica removal, or to aluminium fluoride. One US plant at Aurora, North Carolina makes HF from FSA; Chinese phosphate groups have added FSA-to-HF capacity.
Uses a phosphate waste stream and saves mining; purity control is harder.
USGS MCS 2026 By-product HF from uranium deconversionWhen depleted UF6 is converted back to uranium oxide, the fluorine is recovered as aqueous HF. The US Department of Energy sells it from Paducah and Portsmouth.
Niche; limited by deconversion rates.
USGS MCS 2026 Electronic-grade HF purificationAHF is purified by repeated distillation, membrane and ion exchange steps to parts-per-trillion metal levels and packaged in clean containers. Stella Chemifa and Morita in Japan, Soulbrain in Korea and Chinese makers lead.
High margin; strategic, as Japan's 2019 export curbs on Korea showed.
Indicative Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.