Pelletizing terminology.
Practical definitions, measurement boundaries and the distinctions that matter in plant discussions.
Use this reference alongside the approved test method and project specification. These definitions explain terminology; they do not establish acceptance limits.
Accepted-product yield
Mass of accepted product divided by the specified feed mass, on the same moisture basis and over a balanced period. State whether feed means fresh concentrate, total circuit feed or finished pellets entering handling.
Basicity
A specified ratio of basic to acidic constituents, often expressed as CaO/SiO2. State the exact ratio used; a value without its definition or analysis basis is not enough to compare products.
Bed permeability
The ease with which gas passes through a pellet bed. Size distribution, fines, void space, pellet condition and bed loading all affect the resistance encountered by the gas.
Binder
An addition used to support agglomeration and pellet strength. Assess its dispersion, green and dry behaviour, contribution to final chemistry and effect through the full firing and downstream route.
Cold crushing strength
Resistance of an individual fired pellet to a compressive load in the specified test. Record sample size, pellet size fraction and variability; a mean alone can conceal a weak fraction.
Cut size
A size associated with a defined separation outcome. A measured classification cut is not necessarily identical to the nominal mechanical opening because shape, presentation and material behaviour affect separation.
Dry-basis moisture
Water mass divided by dry-solids mass. At 10% wet-basis moisture, dry-basis moisture is 10/90 = 11.11%. Always state the basis before using moisture in a material balance.
Gangue
Non-iron-bearing mineral constituents in the ore or pellet. Their composition matters as well as their amount; downstream slag and flux consequences depend on the ironmaking and steelmaking route.
Green pellet
A pellet before thermal hardening. It must survive the actual transfers, screening and charging arrangement; an acceptable sample at the disc does not establish acceptable condition at the furnace inlet.
Green-pellet drop test
A procedure assessing impact survival under specified conditions. Drop height, impact surface, pellet selection and the failure definition must be consistent before results can be compared.
HBI
Hot-briquetted iron: direct reduced iron compacted into briquettes while hot. HBI is a downstream iron product; it should not be confused with iron ore pellets supplied to the reduction plant.
Induration
Thermal treatment that hardens green pellets. The route includes drying and heating, with the mineral reactions and bonding processes depending on feed and thermal conditions.
Mass-balance closure
Agreement between measured inputs, outputs and inventory change. Poor closure may indicate inconsistent time periods, sampling bias, moisture-basis differences or unmeasured streams.
Metallisation
Metallic iron divided by total iron in a reduced product, usually expressed as a percentage. It is a measure of reduction outcome, distinct from total Fe grade in the incoming oxide pellet.
On-size recovery
The fraction of the inlet on-size material recovered in the accepted stream. A clean accepted product can still have poor recovery if usable pellets are rejected into return streams.
Partition curve
A plot showing the fraction of each size class reporting to a chosen outlet. It describes separation across sizes more clearly than an undefined single screening-efficiency number.
Recirculating load
Material returned within a process circuit. State whether the ratio is recycle/fresh feed or recycle/total circuit feed; those denominators produce different percentages.
Reducibility
How readily oxygen can be removed from iron oxide under specified test conditions. Report the test method and conditions; reducibility should be interpreted alongside strength and degradation behaviour.
Reduction degradation
Breakdown during exposure to a specified reduction environment. This differs from cold handling abrasion, so a good tumble result does not replace a reduction-related test.
Screen contamination
Off-size material present in the accepted stream. Report undersize and oversize separately, together with the agreed size limits and the sampling point.
Specific energy
Energy consumed per defined unit of output. Distinguish electricity from fuel, gross from net consumption, and accepted product from total circulated tonnes.
Swelling
Dimensional or volume change of pellets during a specified reduction test. The interpretation depends on the method and downstream application; it is not a substitute for complete product qualification.
Tumble and abrasion indices
Measures derived from a specified mechanical degradation test. Interpret the retained and fine fractions using the stated method and apertures; different procedures are not directly interchangeable.
Wet-basis moisture
Water mass divided by total wet mass. For 100 t of material at 9% wet-basis moisture, water is 9 t and dry solids are 91 t.
Make every number comparable
For any reported result, record the unit, denominator, moisture basis, sampling point, test method and period. Many apparent technical disagreements are differences in one of these six fields.
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