Magnesium Metal Export Pricing Basis and Grade Selection

Metal Magnesium as an Export Commodity: Forms, Grades and Trade Terms

In international trade, "metal magnesium" is a product family rather than a single specification. The family covers unalloyed primary magnesium in ingot or stick form, cast and wrought magnesium alloys, granulated magnesium and magnesium powder, and magnesium-bearing master alloys consumed by steelmakers and foundries. Each of those carries a different chemical specification, a different classification for carriage, and a different cost structure. An offer described only as "magnesium" therefore cannot be compared with a competing offer until the form, the grade and the delivery basis are fixed in writing.

The first split to settle is unalloyed versus alloyed. Unalloyed primary magnesium is bought against a minimum magnesium content, for example 99.95% or 99.90% Mg, with tight ceilings on iron, silicon, nickel and copper. Magnesium alloys such as the AZ and AM die-casting families are bought against a full composition window covering aluminium, zinc, manganese and silicon, and the magnesium content is merely the balance. A works certificate that states "magnesium, balance" tells a buyer nothing about castability or corrosion behaviour, because those are governed by the alloying elements and by the impurity ceilings, not by the residual magnesium figure.

Primary Magnesium Grades and Chemical Specifications

Unalloyed magnesium ingot is graded by minimum magnesium content and by maximum permitted impurities. The grading pattern used in Chinese production and mirrored in international specifications such as ASTM B92/B92M is built on a descending purity ladder: Mg9999, Mg9995, Mg9990 and Mg9980, where the digits express the minimum magnesium content. Impurity control matters most for nickel, copper and iron, because those three elements dominate the corrosion performance of the finished part far more than the magnesium figure itself. Magnesium alloy ingots for sand casting, permanent mould casting and die casting are specified separately, with AZ91D and AM60B among the most widely traded die-casting grades; their compositional windows are set out in ASTM B93/B93M and in ISO 16220, and the codification of cast and wrought magnesium alloys follows ASTM B951.

Grade band	Mg (min, %)	Fe (max, %)	Si (max, %)	Ni (max, %)	Cu (max, %)	Typical use
Mg9999	99.99	0.003	0.003	0.0005	0.0005	High-purity alloying, special metallurgy
Mg9995	99.95	0.004	0.010	0.001	0.002	Die-casting alloy feed, aluminium alloying
Mg9990	99.90	0.020	0.020	0.001	0.005	General alloying, reagent manufacture
Mg9980	99.80	0.050	0.050	0.002	0.020	Deoxidation, nodularising, general metallurgy

The figures above represent typical commercial bands rather than a contractual limit. The grading logic follows the GB/T 3499 family for primary magnesium ingot and the ASTM B92/B92M family for unalloyed ingot and stick, and buyers should anchor acceptance on the certificate of analysis issued for the specific heat rather than on a generic grade label. Chemical analysis of magnesium and magnesium alloys is covered by the GB/T 13748 series, which includes titrimetric, spectrophotometric and instrumental methods for the elements that matter commercially.

Physical and Metallurgical Properties That Decide the Application

Pure magnesium has a density of about 1.74 g/cm3, roughly two thirds that of aluminium, a melting point near 650 degrees Celsius and a boiling point near 1090 degrees Celsius. It crystallises in a hexagonal close-packed lattice, which limits room-temperature ductility in the wrought condition and explains why most commercial tonnage is consumed as a casting alloy or as an alloying addition rather than as a structural wrought product. Thermal conductivity of about 156 W/m.K and a Young's modulus near 45 GPa place it squarely in the light-metal class rather than the structural-steel class.

Chemically, magnesium is a strong reducing agent. That single property underpins three of its largest industrial uses: it reduces titanium tetrachloride to titanium sponge, it removes sulphur and oxygen from molten steel and iron, and it combines with silicon and iron to form nodularising master alloys for ductile iron. It also means that magnesium in finely divided form is reactive with water and with some oxidising agents, a fact that changes packaging, insurance and carriage requirements and that must be reflected in the contract.

How Primary Magnesium Is Produced

Two process routes dominate world supply. The silicothermic route, normally associated with the Pidgeon process, calcines dolomite and reduces the resulting oxide with ferrosilicon under vacuum at high temperature. The electrolytic route dehydrates and chlorinates magnesium-bearing feed and electrolyses molten magnesium chloride. Both routes are energy-intensive; the silicothermic route is also reductant-intensive, with published process studies placing ferrosilicon consumption in the region of one to one and a third tonnes of FeSi75 per tonne of magnesium produced, together with several tonnes of coal equivalent for calcination and heating.

That process dependency has a direct commercial consequence: the cost of magnesium is structurally linked to the cost of ferrosilicon and to local energy prices. Ferrosilicon reductant is normally bought to the GB/T 2272 specification for FeSi75, with silicon in the 74 to 80 percent range, because silicon yield per tonne of reductant decides the reduction economics. Buyers who follow magnesium pricing should therefore also follow ferrosilicon availability and the electricity and coal situation in the producing provinces, since these are upstream of the metal price rather than independent of it.

Where Magnesium Is Consumed

Aluminium alloying is the largest single outlet, because magnesium at a few percent raises the strength and corrosion resistance of Al-Mg and Al-Mg-Si wrought alloys and improves the machinability of casting alloys. Die casting follows closely, with AZ91D and AM60B used for automotive structural and interior components, power tool housings and electronic enclosures where weight reduction justifies the material premium. Ductile iron production consumes magnesium in nodularising master alloys and in treatment wire, where the magnesium addition converts flake graphite into nodular graphite and lifts ductility dramatically.

Steel desulphurisation is another major outlet: magnesium-bearing reagents injected with lime-based powders remove sulphur from hot metal to the low levels required for linepipe, plate and forging grades. Titanium production consumes magnesium in the reduction of titanium tetrachloride to sponge, and the resulting magnesium chloride is either recycled by electrolysis or sold on. Smaller but specification-sensitive outlets include sacrificial anodes for cathodic protection, which are specified under ASTM B843, and the manufacture of organometallic chemicals and reducing agents.

Cost Structure Behind a Magnesium Export Price

A magnesium export price is the sum of a raw material and energy stack plus conversion, packaging, inland movement, compliance and freight, not a figure that follows a published index mechanically. The dominant variables are the cost of dolomite, ferrosilicon and coal, the electricity tariff in the producing region, labour and maintenance in an energy-intensive furnace operation, and the level of capacity utilisation. When furnaces run below capacity, fixed cost per tonne rises sharply, which is why magnesium prices can move faster than the underlying raw material costs.

Grade and form are the next layer. Moving from Mg9980 to Mg9995 requires tighter refining control and higher recovery losses, so the price ladder across grades is not linear. Granules and powder carry an additional milling and passivation cost and a different carriage classification from ingots. Packaging is a real cost line as well: strapped ingot bundles, pallets, and moisture-barrier packing for powder all add to the delivered figure, and a printed price that omits packaging specification is not yet comparable.

Policy, currency and logistics complete the stack. Export tax treatment, energy-consumption policy in producing provinces, inspection requirements and seasonal transport constraints can each shift the relationship between the domestic ex-works price and the export price. Because the industry has seen repeated adjustments to export rebate and energy policy, a procurement file should record the policy position applicable on the quotation date rather than rely on a rate remembered from an earlier contract. Freight adds further variability: magnesium is normally shipped as containerised cargo at a high volume-to-value ratio, so ocean freight and container availability move the landed cost materially, and inland haulage from an inland producing region to a seaport is a separate, sometimes dominant, item.

Quotation Basis and How to Compare Offers

Comparisons should be made on a single, fully specified basis. Fix the following in writing before comparing numbers: product form and grade with the required impurity ceilings; unit and quantity, whether per metric tonne of net weight or per kilogram; Incoterms basis, including named port or place; packaging and palletisation; whether the price is tax-inclusive or exclusive and whether any export tax treatment has been applied; the certificate of analysis regime; and the tolerance for weight and analysis. Any offer missing one of these items should be normalised before it enters the comparison table.

The practical method is to convert every offer to a delivered cost per tonne of contained magnesium on a stated Incoterms basis. That calculation strips out the effect of grade basis, moisture and weight tolerance, packaging and freight, and it exposes offers that look cheap per tonne only because they are quoted on a different form or a different port. Two further checks repay the effort. First, verify that the price is tied to a grade that the producer can actually repeat heat after heat, not to a one-off sample. Second, verify the analysis regime: who samples, who analyses, which methods are used and how a disagreement is resolved.

Inspection, Packaging and Carriage Requirements

Incoming material should be inspected against a documented regime covering sampling, chemical analysis, visual condition and unit weight. Sampling and sample preparation practice for these products follows the iron-alloy and non-ferrous practice of composite sampling from a defined proportion of units, with the analysis performed by the methods in the GB/T 13748 series for magnesium and magnesium alloys. For ingot, the inspection should also confirm the absence of excessive surface oxidation, slag inclusion and moisture, because damp or contaminated bundles are a common cause of complaints and of rejected cargo at destination.

Packaging for ingot is normally mill-strapped bundles of a defined piece count and target weight, palletised or handled as breakbulk units depending on the shipment. Powder and granulated product must be packed to exclude moisture and to suit the hazard classification. Magnesium metal and its alloys are classified under UN 1869 for carriage, with the applicable hazard class and packing requirements depending on form and particle size; the shipper is responsible for the correct entry, and the buyer should see the shipping documents rather than assume that an ingot cargo and a powder cargo follow the same rules. Documentation should include the certificate of analysis, packing list with net and gross weight, and any inspection certificate agreed in the contract.

Storage, Handling and Safety Points

Magnesium ingot is stable in ordinary dry storage, but it should be kept under cover, clear of standing water, and separated from acids, chlorinated solvents and oxidising agents. Fine material, turnings and powder need more care, because surface area governs reactivity; such material should be stored dry, away from ignition sources, and handled according to the material safety data sheet. Warehouse fire precautions for magnesium differ from those for ordinary metals: water must not be used on burning magnesium unless the responsible fire authority confirms an approved method, and the correct approach is to smother with dry powder or approved media.

On the melt side, magnesium must be handled under a protective cover gas or flux to prevent oxidation, and flux residues must be removed before the metal is charged to a subsequent process. Buyers specifying magnesium for foundry use should therefore also confirm the surface treatment and residual flux condition of the delivered product, not only the chemical analysis, because residual chloride-bearing flux is a corrosion risk in the finished casting.

Common Misconceptions in Magnesium Purchasing

Three misconceptions recur. The first is that a higher magnesium figure guarantees better performance; in practice nickel, copper and iron ceilings govern corrosion behaviour and are the numbers that should be tightened when a part fails prematurely. The second is that any magnesium grade can substitute for any other with an adjustment to charge weight; alloying windows and reductant performance are not that forgiving, and substituting an off-specification grade into a nodularising or alloying operation usually costs more in rejects than it saves in material. The third is that the export price is a stable function of the magnesium content alone; the price is sensitive to ferrosilicon and energy costs, to capacity utilisation and to policy changes, so a purchase programme that ignores the upstream drivers will either overpay in tight periods or misjudge the risk of a price spike.

FAQ

Q: What is the difference between Mg9995 and Mg9990 primary magnesium ingot?
Mg9995 is specified at 99.95 percent minimum magnesium with tighter impurity ceilings, while Mg9990 is specified at 99.90 percent minimum with wider ceilings on iron and silicon. The higher grade is normally selected for die-casting alloy feed and critical aluminium alloying, and the lower grade for general metallurgical additions.

Q: Why do nickel and copper limits matter more than the magnesium content?
Nickel, copper and iron have a disproportionate effect on the corrosion resistance of magnesium and its alloys, so a small excess can cause premature failure in service. Specifications therefore set very low ceilings on these elements, and acceptance should be based on the certificate of analysis for the actual heat.

Q: How is the magnesium price linked to ferrosilicon?
The dominant silicothermic route reduces magnesium oxide with ferrosilicon, consuming roughly one to one and a third tonnes of FeSi75 per tonne of magnesium. Ferrosilicon cost and availability, together with coal and electricity prices in the producing region, are therefore upstream drivers of the magnesium price.

Q: What should be fixed in writing before comparing magnesium offers?
Form, grade and impurity ceilings, quantity and unit of measure, Incoterms basis with named port, packaging and palletisation, tax and export treatment, certificate regime, and weight and analysis tolerances. Offers missing any of these should be normalised to a delivered cost per tonne of contained magnesium before comparison.

Q: How is magnesium classified for sea carriage?
Magnesium and magnesium alloys are listed under UN 1869, and the applicable hazard class and packing requirements depend on the form and particle size of the consignment. Ingot, granules and powder are not interchangeable for carriage purposes, and the shipping documents should be checked against the actual form supplied.

Q: Can magnesium be substituted between grades to reduce cost?
Only where the receiving process tolerates the change. Substituting a lower grade in ductile iron nodularising, in steel desulphurisation or in an alloying window changes recovery, treatment time and rejection rates, so the saving on material is often smaller than the loss in yield and quality.