Fluorspar splits into two distinct commercial products — acid grade, the far larger of the two, and metallurgical grade — and U.S. supply of both depends entirely on imports concentrated in a handful of countries. This page covers that grade split and what research shows about why the amount of CaF2 in a steelmaking desulfurizer matters.
What is it?
Fluorspar (calcium fluoride, CaF2) is a mineral used mainly to produce hydrogen fluoride and as a flux in steelmaking. Per the U.S. Geological Survey’s Mineral Commodity Summaries 2025, U.S. fluorspar consumption relied on imports for 100% of apparent consumption in 2024, sourced primarily from Mexico (62%), Vietnam (14%), South Africa (9%), and China (4-8%) over 2020-23. In 2024, the U.S. imported an estimated 440,000 tons of fluorspar, split between acid-grade (400,000 tons) and metallurgical-grade (40,000 tons) material.
Why should I use it?
- Acid-grade fluorspar is the dominant global product, used to produce hydrogen fluoride (HF) — the feedstock behind most fluorine-based chemicals — see “What is it?” above.
- Metallurgical-grade fluorspar has a research-documented role as a flux that measurably improves steelmaking desulfurization when used within a specific composition range — see Limitations.
How it’s used
Per the USGS, CaF2 is used in producing anhydrous hydrogen fluoride, described as “by far the leading use for acid-grade fluorspar.” HF is then, per the same source, “the primary feedstock for the manufacture of virtually all fluorine-bearing chemicals, particularly refrigerants and fluoropolymers,” and is also a key ingredient in aluminum and uranium processing. Beyond HF production, fluorspar is also used in cement production, in enamels, as a flux in steelmaking, in glass manufacture, in iron and steel casting, and in welding rod coatings.
Limitations — when it isn’t the right choice
- U.S. supply of fluorspar is 100% import-dependent and concentrated in a small number of countries — a genuine supply-chain consideration, not just a cost one. Per the USGS, essentially all U.S. consumption in 2024 came from imports, with Mexico alone supplying 62% of the 2020-23 total, followed by Vietnam, South Africa, and China. Anyone specifying fluorspar or HF-derived chemicals for a critical process should factor in this sourcing concentration.
- The steelmaking-flux benefit of metallurgical-grade fluorspar is composition-range specific and was demonstrated at bench scale, not full industrial scale. A 2025 peer-reviewed study combined thermodynamic modeling with lab-scale slag-steel contact experiments (210 g of molten steel, 1600°C) to test CaO-CaF2-based desulfurizers. It found that a composition of roughly 60% CaO, 30% CaF2, and 0-5% SiO2 reached a slag breaking temperature below 1350°C and cut sulfur content below 0.002 wt% within 5 minutes in these bench tests, while a lower CaF2 content (15 wt%) showed a higher breaking temperature and more crusting tendency. This shows CaF2 content matters within the tested 15-35 wt% range, but it should not be read as “more CaF2 is always better,” and the results come from bench-scale testing rather than an industrial furnace trial.
