Mineral, ore, concentrate
- Mineral
- A natural solid with a defined chemical composition and crystal structure. Fluorite (CaF₂) is a mineral.
- Ore
- Rock from which the valuable component can be recovered economically. Manganese ore is a mixture of manganese minerals and the host rock.
- Concentrate
- Ore whose grade has been raised by beneficiation. Most purchased material is concentrate.
The main minerals used in metallurgy
| Mineral | Function in metallurgy |
|---|---|
| Fluorite (CaF₂) | Increases slag fluidity and lowers its melting point. Used in steelmaking and in welding electrode coatings. |
| Limestone and dolomite | Form a basic slag; tie up sulphur and phosphorus and protect the refractory. |
| Manganese ore | The raw material for ferromanganese and silicomanganese production. |
| Graphite | Carbon source, heat conduction in ladles and refractories, foundry mould coating. |
| Petroleum coke | Carbon source and electrode raw material; used after calcination. |
| Silicon carbide (SiC) | Deoxidiser and heat source in cast iron, refractory and abrasive. |
| Bauxite | The raw material for aluminium production; also a slag conditioner and refractory input. |
| Zircon and chromite sand | Foundry mould and core sand, high-temperature refractories. |
Assessment criteria
- Grade
- The percentage of the valuable component — CaF₂ in fluorspar, Mn in manganese ore. Pricing generally follows the grade.
- Impurities
- SiO₂, Al₂O₃, sulphur, phosphorus and alkali content. In metallurgical fluxes, excess silica upsets the basicity of the slag; sulphur and phosphorus carry through into the end product.
- Particle size
- The distribution range and the proportion of fines. It governs both reaction rate and dust loss.
- Moisture
- Can rise during storage and transport. A wet charge creates a risk of explosion in the furnace and loss of energy. Prices are generally set on a dry basis.
- Hardness and abrasiveness
- Affects wear on handling and feeding equipment; decisive for materials such as SiC.
Sampling and analysis
In mineral purchasing, how the sample was taken matters as much as the analysis result. A single sample drawn from a bulk cargo does not represent the lot.
- Samples should be taken from the stream at regular intervals during loading or discharge.
- The increments taken are combined and divided down to prepare the laboratory sample.
- Moisture is determined on a separate sample, weighed immediately.
- Analysis results should be reported converted to a dry basis.
- A witness sample should be retained for any dispute, and an umpire laboratory agreed by both parties should be named in the contract.
When you buy
- State the grade and the acceptable lower limit; set the price deduction or rejection terms below that limit.
- Give upper limits for the critical impurities.
- State the particle size range and the tolerance for fines.
- Put the moisture limit and the dry-basis pricing principle into the contract.
- Write the sampling and analysis method together with its standard.
Frequently asked questions
What is an industrial mineral?
A natural material used not to extract the metal inside it but for its own physical and chemical properties. In metallurgy they serve as slag formers, carbon sources, abrasives and refractories.
What is fluorspar used for in metallurgy?
It increases slag fluidity and lowers its melting point. It is used as a slag conditioner in steelmaking and in welding electrode coatings. When buying, the CaF₂ grade together with the upper limits for SiO₂ and sulphur are the decisive parameters.
What is the difference between ore and concentrate?
Ore is the raw rock from which the valuable component can be recovered economically. Concentrate is ore whose grade has been raised by beneficiation. Most material purchased by industry is concentrate.
Why does moisture matter when buying minerals?
Moisture rises during transport and storage; a wet charge creates energy loss and a safety risk in the furnace. Prices are generally set on a dry basis, so the moisture limit and the dry-basis pricing principle should be written into the contract.
Items covered in this article
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