Manganese Metal Briquettes: Grades, Deoxidation Use and Handling

What Manganese Metal Briquettes Actually Are

Manganese metal briquettes are a compacted metallurgical product made from manganese metal powder, mill scale-free flake or fine screenings that are pressed into pillow-shaped or oval briquettes without a binder, relying on mechanical interlocking and light sintering at the surface. In the trade they are often called manganese balls or manganese metal briquettes, and their purpose is practical rather than decorative: they convert a dusty, high-surface-area material into a dense, free-flowing addition that survives pneumatic conveying, hopper discharge and free fall into a ladle.

Chemically they belong to the metal-manganese family, not to the ferromanganese family. The distinction matters at the purchasing desk. Ferromanganese is a carbon-bearing master alloy covered by GB/T 3795, with carbon from about 0.5% in the refined grades up to 7.5% in the blast-furnace grades. Metal manganese is produced by electrolysis or by aluminothermic reduction and supplied at a nominal manganese content near 99.7%, which is the grade normally described in the applicable GB/T specification for metal manganese. Briquettes sit between the two worlds: they are made from metal manganese, so they are low in carbon and phosphorus, but they are pressed with a small amount of process residue and are therefore bought on a 95-97% Mn basis rather than on a 99.7% basis.

For a steel plant the commercial consequence is simple. Where the heat needs manganese without extra carbon, and where the charge mix is already tight on phosphorus, a metal-manganese briquette lets the melter add the alloying unit without dragging in the carbon and phosphorus load that a high-carbon ferromanganese would bring.

Typical Chemistry and How Grades Are Written on a Purchase Order

Briquette chemistry follows the metal manganese feed, so the analysis is dominated by manganese, with carbon, sulphur, phosphorus, iron and silicon as the controlled residuals. Silicon is usually the largest residual because electrolytic manganese carries a small silicon figure and because some producers blend in silicomanganese fines. The table below shows the ranges that are normally quoted in a commercial certificate of analysis for pressed manganese metal briquettes; a purchase order should always fix the actual limits rather than accept a range.

Element	Typical commercial range	Why the purchaser controls it
Mn	95.0-97.0%	Payment basis; the balance is residual oxide, iron and silicon
C	0.10% max, low-carbon grades 0.05% max	Ultra-low-carbon and interstitial-free heats cannot absorb carbon from the addition
Si	0.50-1.50%	Silicon acts as a deoxidiser but also raises the inclusion load
P	0.005% max	Phosphorus is the main penalty element in the metal-manganese route
S	0.05% max	Sulphur is deliberately kept low so the addition does not fight the desulphurisation step
Fe	0.30-0.70%	Iron is not harmful but must be accounted for in the alloy balance
Moisture	0.20% max as packed	Moisture drives hydrogen pickup and fume during ladle addition

Two numbering conventions appear on certificates. The first is a straight manganese figure with a carbon suffix, for example a 97/0.10 specification. The second mirrors the ferromanganese style used in GB/T 3795, where the grade designation carries the manganese level and the carbon level together, such as FeMn78C2.0 for a high-purity ferromanganese. The second style is convenient for comparison but must not be confused with a metal-manganese certificate: a briquette declared at 97% Mn is not a FeMn78 grade, and substituting one for the other changes both the manganese yield and the carbon load per tonne of steel.

Why Press into a Briquette Instead of Shipping Flake or Lump

Electrolytic manganese leaves the cell as a brittle flake or sheet. Flake is awkward to handle: it bridges in silos, it generates dust that carries manganese fume into the workplace, and its low bulk density means a ladle addition of a given mass occupies a large volume and floats on the slag rather than penetrating the steel. Pressing into a briquette changes three physical properties at once.

Bulk density rises sharply. Loose flake typically bulk-stows at a low figure, while pressed briquettes reach a bulk density in the region of 2.4-3.0 t/m3 depending on shape and pressing pressure. Higher bulk density means fewer truck loads per tonne and a smaller footprint in the alloy bay.

Segregation and dust are suppressed. A briquette resists the fines separation that occurs when a polydisperse flake pile is poured, so the manganese content delivered to the ladle stays close to the manganese content sampled at the silo. Dust suppression also reduces respiratory exposure, which is a real compliance issue because manganese fume has an occupational exposure limit in most jurisdictions.

Solution and recovery behaviour becomes predictable. The compact dissolves from the outside in, so recovery depends mainly on bath temperature, holding time and stirring rather than on the size distribution of the feed. That predictability is what allows a melter to trim the manganese addition to within a few hundredths of a percent instead of adding a safety margin.

There is a counter-argument that deserves mention. A tightly pressed briquette with a very low porosity can sink through the slag and sit on the bottom of the ladle, dissolving slowly and giving a poor recovery in a short ladle-treatment cycle. The remedy is not a looser briquette but a correct addition practice: add at the correct bath temperature, use argon or electromagnetic stirring, and avoid dumping briquettes into a cold ladle before tapping.

The Three Functions in Steelmaking: Deoxidation, Desulphurisation, Alloying

Deoxidation. Manganese has a moderate affinity for oxygen, stronger than iron and weaker than aluminium, silicon or calcium. Its deoxidation product, MnO, is liquid at steelmaking temperatures and coalesces into a slag or a liquid inclusion, which is why manganese is normally used in combination with silicon or aluminium rather than alone. A silicon-manganese deoxidation practice forms liquid MnO-SiO2 inclusions that are easier to float out than pure silica; adding manganese in the form of a metal briquette to a rimmed or semi-killed practice achieves a similar effect.

Desulphurisation. Manganese reacts with dissolved sulphur to form manganese sulphide. Because MnS has a high melting point and forms globules rather than continuous films at grain boundaries, manganese suppresses the hot shortness that iron sulphide would cause during rolling. The practical rule in steelplants is to hold a manganese-to-sulphur ratio of roughly 20:1 or higher in the finished product; a ratio below about 15:1 is a warning sign for surface cracking on continuously cast slabs.

Alloying. Manganese raises hardenability, stabilises austenite, increases strength in solid solution and, at high levels, produces the fully austenitic structure of the high-manganese wear-resistant castings covered by GB/T 5680. Because the briquette carries essentially no carbon, it is the preferred trimming addition when a heat is short on manganese but already at the carbon specification, a situation that is common in low-carbon and interstitial-free grades where the carbon window is only a few hundredths of a percent wide.

Where the Material Is Actually Consumed

Flat products and automotive sheet. Low-carbon aluminium-killed and interstitial-free steels use metal manganese to trim manganese without carbon pickup. Because these heats are often vacuum degassed, the addition is usually made in the ladle before or during degassing so that the manganese oxide products have time to float.

Long products and wire rod. Rebar, prestressing strand and cold-heading quality wire need a controlled Mn:S ratio to avoid rolling cracks. Metal briquettes are used to top up manganese at the end of the heat when the analysis is slightly low and a second ladle of ferromanganese would overshoot the carbon.

High-manganese austenitic steels. Wear parts, crusher liners, railway frogs and impact-resistant castings rely on manganese levels of 11-14% with carbon around 1.0-1.3%, produced to GB/T 5680. Here the manganese addition is mostly made with ferromanganese for cost reasons, and metal briquettes are used for final trimming and for the small heats where a low-phosphorus feed is essential.

Welding consumables. Covered electrodes and flux-cored wires use manganese metal to balance the manganese that is lost to the slag and to the fume during welding. Briquettes are milled back to powder for this route, so the purchase specification usually imposes a tighter particle size and a lower moisture limit than the steelplant grade.

Aluminium and copper alloy melting. Metal manganese enters aluminium 3xxx alloys and copper-manganese alloys, but in most foundries the addition is made through a 10-20% Al-Mn or Cu-Mn master alloy rather than through pure manganese, because the melting point of pure manganese and its limited solubility in liquid aluminium make direct addition inefficient. This is one of the most common misunderstandings in sourcing: a purchaser who specifies briquettes for an aluminium melt should confirm that the foundry really intends a direct addition.

The Production Route behind the Certificate

The chain starts with manganese ore, which is leached in sulphuric acid after reduction, purified to remove iron and heavy metals, and then electrowon onto cathodes as manganese metal. The cathode product is stripped as brittle flake, washed, dried and crushed. To make briquettes, the crushed flake and fines are screened, adjusted for moisture, and pressed in a roll or punch press at high pressure; some producers apply a light heat treatment to improve green strength without sintering the whole mass. The result is a product with a controlled size, a controlled manganese content and a residual moisture that must be kept low to avoid hydrogen-related defects in the steel.

Sampling and testing follow the general ferroalloy rules. GB/T 4010 and ISO 3713 describe how to take and prepare a sample from a lot, GB/T 13247 covers the determination of particle size range, and GB/T 3650 covers acceptance, packing, marking, storage and the quality certificate. A purchaser who wants a defensible acceptance decision should specify the lot size, the sampling method and the size test in the order, because a dispute over a 0.3% manganese difference is impossible to settle if the sample was taken with a shovel from the top of the container.

Specification Checklist for the Purchase Order

Parameter	What to state	Test or evidence
Mn basis	95% min or 97% min, with the payment basis stated	Certificate of analysis per lot, wet chemical or XRF
C, S, P limits	Maximum values, not ranges	Combustion infrared for C and S, ICP or photometry for P
Size	Nominal size band and undersize allowance	Sieve test to GB/T 13247
Bulk density	Minimum figure agreed with the handling system	Measured on a settled sample in a fixed volume
Moisture	0.2% max as packed	Loss on drying at 105 C
Packing	Big bag or steel drum, with the net mass declared	Marking and certificate to GB/T 3650
Lot definition	Maximum tonnes per lot for sampling purposes	Sampling plan agreed in writing

Three commercial points are worth building into the order. First, declare whether the manganese figure is a minimum or a typical value, because a 95% minimum with a 96.8% typical is a different commercial proposition from a flat 95%. Second, define the size band in both directions; an oversize briquette that will not pass a charging chute is as much a defect as a pile of fines. Third, require the certificate to state the analysis of the actual lot rather than a general product sheet, and require retention samples so that a re-test is possible.

Handling, Storage and Workplace Safety

Manganese briquettes are not a dangerous good for transport, but they are not inert either. The fines fraction oxidises slowly in damp air, and wet material generates hydrogen when it meets moisture and steel. Storage should be under cover, on a drained hardstanding, in closed big bags or drums, with the oldest stock issued first. A stack that has been open to rain for a season will show surface oxidation, a brownish bloom and a measurable drop in metallic manganese; that material should be re-sampled rather than charged on the original certificate.

From an occupational health standpoint, the risk arises when briquettes are crushed, milled or added to a ladle and manganese fume is generated. Local exhaust ventilation at the addition point, respiratory protection where exposure cannot be controlled by engineering means, and routine air monitoring are the standard controls. Dust from handling should be kept down by avoiding free fall and by using enclosed conveying. Spilled material should be swept, not washed into drains, because soluble manganese from the surface layer can migrate into watercourses.

Moisture also has a metallurgical consequence beyond handling. Each 0.1% of moisture in the addition introduces hydrogen into the steel bath; in heavy sections and in steels with a high hardenability this shows up later as flakes or as delayed cracking after cooling. Drying the addition, or at least keeping it dry, is cheaper than a downstream ultrasonic rejection.

Common Misconceptions Worth Correcting Early

"Briquettes are just compressed scrap." They are not. The feed is metal manganese, and the certificate should show a manganese level above 95% with controlled phosphorus and sulphur; a compressed by-product stream would not pass that analysis.

"A higher manganese figure always means a better purchase." A 97% briquette with 1.5% silicon and 0.02% phosphorus may be a worse buy for a low-phosphorus heat than a 95% briquette with 0.5% silicon and 0.005% phosphorus, because the penalty elements cost more to correct than the manganese is worth.

"Recovery is always above 95%." Recovery depends on bath temperature, slag condition, stirring and the oxygen potential at the moment of addition. In a cold ladle with a thick oxidising slag, a third of the addition can be lost to the slag as MnO, and that loss is invisible in the charge calculation unless the plant tracks it.

"Briquette size does not matter." It matters twice: to the handling system, which may not accept a 60 mm piece, and to the dissolution kinetics, which determine whether the manganese is in solution before the heat is cast.

FAQ

Q: What is the typical manganese content of metal manganese briquettes?
Pressed manganese metal briquettes are normally sold on a 95-97% Mn basis, with carbon at 0.10% max, phosphorus at 0.005% max and sulphur at 0.05% max; the exact limits must be fixed in the purchase order and confirmed on the lot certificate.

Q: How do briquettes differ from ferromanganese in the charge calculation?
Ferromanganese carries carbon from about 0.5% to 7.5% depending on the grade under GB/T 3795, whereas metal briquettes carry about 0.1% carbon or less, so the briquette adds roughly one manganese unit without adding a significant carbon load per tonne of steel.

Q: What size and shape are manganese briquettes supplied in?
The common commercial form is a pillow or oval briquette in the 30-50 mm band, sometimes 20-60 mm, with a bulk density around 2.4-3.0 t/m3; the size band and the permitted undersize should be agreed against a sieve test performed to GB/T 13247.

Q: Why is the manganese-to-sulphur ratio important?
Manganese combines with sulphur to form MnS globules instead of grain-boundary FeS films, and steelplants generally aim for an Mn:S ratio of at least 20:1; below roughly 15:1 the risk of hot shortness and surface cracking during rolling rises sharply.

Q: Can manganese briquettes be used in an aluminium foundry?
Direct addition is inefficient because pure manganese melts at about 1246 C and dissolves slowly in liquid aluminium, so most foundries use a 10-20% Al-Mn master alloy instead and the briquette route is mainly a steelmaking and welding-consumable practice.

Q: How should a delivered lot be sampled and stored?
Sample the lot according to GB/T 4010 or ISO 3713, test the size fraction to GB/T 13247, pack and mark to GB/T 3650, and store under cover on a drained floor because damp fines oxidise and introduce hydrogen into the steel bath.

Q: Does the briquette dissolve completely in the ladle?
Complete dissolution requires sufficient superheat, a fluid slag and some form of stirring; in a short ladle cycle with no stirring, coarse briquettes can remain partly undissolved and the measured manganese recovery will fall below the 90-95% range that a well-controlled practice achieves.