Industrial Fluorspar Technical FAQ: Purity, Impurities, EFU and Sourcing
A technical FAQ for industrial fluorspar buyers covering CaF2 purity, silica, effective fluorine units, trace impurities, moisture verification, flotation, COA review, and sourcing questions.
Technical focusCaF2 / SiO2 / EFU
Buyer useRFQ / COA review
Risk checksMoisture / impurities
Direct answer
Industrial fluorspar buyers should not evaluate a cargo by CaF2 alone. The practical specification should connect CaF2, silica, calcium carbonate, moisture, trace impurities, physical form, sampling basis, and the intended process use.
For metallurgical buyers, effective fluorine units can help compare the true fluxing value of a material. For acid-grade buyers, silica and moisture usually deserve close attention because they influence reaction efficiency, handling, and downstream process control.
How to calculate effective fluorine units
Effective fluorine units, often shortened to EFU, are used by some metallurgical buyers to compare the practical fluxing value of fluorspar after considering silica.
A common calculation is EFU = %CaF2 - (2.5 x %SiO2). For example, a material with 80% CaF2 and 5% SiO2 has an EFU of 67.5. Buyers should confirm the exact formula and acceptance method with their own plant or technical adviser before using EFU in a contract.
Why silica matters in acid-grade fluorspar
Silica is one of the first impurity fields many acid-grade buyers review. Higher silica can affect reagent consumption, reaction behavior, residue handling, and downstream quality expectations.
The acceptable limit depends on the buyer's process and contract standard. Instead of relying on a generic grade name, the RFQ should state the target CaF2 and the maximum SiO2 limit together.
Trace impurities for higher-purity applications
Arsenic, phosphorus, sulphur, iron, and other trace elements may matter when fluorspar is used in more sensitive downstream chemical routes. The relevant limit is process-specific.
Buyers should ask for a representative COA, clarify the sampling basis, and confirm whether the supplier can discuss low-sulphur, low-phosphorus, or tighter trace-element requirements before quotation.
Moisture and drying checks
Moisture affects cargo weight, storage behavior, handling, and some downstream processes. For dried fluorspar powder, the RFQ should state the target moisture limit and the test basis.
Buyers should ask whether moisture is measured by lot, shipment, or another sampling basis, and whether the result appears clearly on the COA or inspection document.
What to ask before sourcing
A useful technical RFQ should state product form, target CaF2, SiO2 limit, other impurity limits, moisture, particle size, packing, monthly quantity, destination port, inspection requirement, and intended application.
If the buyer needs a technical data sheet or safety document, request it at the RFQ stage so documentation does not become a delay after price negotiation.
How do I calculate effective fluorine units in fluorspar?+
A common EFU calculation is %CaF2 - (2.5 x %SiO2). Buyers should confirm the accepted calculation method with their own plant before using it in a contract.
Why is silica important in acid-grade fluorspar?+
Silica can affect reaction efficiency, reagent consumption, residue handling, and downstream quality. The RFQ should state CaF2 and SiO2 requirements together.
Which trace impurities should buyers check?+
Common concern points include arsenic, phosphorus, sulphur, iron, calcium carbonate, and silica, but the relevant limits depend on the end use.
How should moisture be verified?+
The buyer should ask for the moisture limit, test basis, sampling method, and whether the result is tied to the lot or shipment COA.
What should a technical fluorspar RFQ include?+
It should include product form, target CaF2, impurity limits, moisture, particle size, packing, quantity, destination port, inspection basis, and intended application.
