Mixing & dosing
Bring the feed, binder and required additives together before balling.
What happens here
Mixing prepares a blended feed for pellet formation. Binder and additive choices must be assessed against both green-pellet behaviour and the final product requirements.
Equipment in this stage
Dosing equipment and mixers.
Inputs to define
Recipe and dosage basis; mixing duty; water addition; material transfer and control interfaces.
A useful review question
Record the recipe revision and the conditions of any trial. Avoid attributing a change to one additive when several inputs changed at once.
Continue to the practical guide ↗The recipe is both chemistry and distribution
Binder selection involves how material disperses, how water moves through the pellet and how particles remain bonded. The binder reviews linked below discuss these connected roles. A higher nominal dosage does not prove that every portion of the feed receives the intended amount. Before changing a recipe, establish feeder calibration, continuity of delivery and the repeatability of mixing.
Report additions per tonne of dry concentrate or another explicitly defined solids basis. Include moisture in the concentrate and any liquid additive. If the recipe changes with wet feed rate while solids content drifts, actual addition per tonne of solids also changes.
Turn a binder trial into a controlled comparison
| Hold or record | Measure | Decision supported |
|---|---|---|
| Ore lot, feed fineness and moisture | Green size distribution and handling test results | Whether an apparent improvement comes from binder rather than feed. |
| Additive source, batch and calibration | Actual dose and distribution consistency | Whether the dosing system delivered the intended trial. |
| Drying and firing conditions | Dry strength and fired physical/metallurgical properties | Whether green-pellet improvement survives the complete process. |
| Trial length and circuit inventory | Results after the previous recipe has cleared | Whether transition material is biasing the conclusion. |
Organic and inorganic binders should be compared through the complete product route. The inorganic-binder review discusses the compromise between pellet chemistry and physical or metallurgical quality. The organic-binder review highlights dispersion and material consistency. Neither category is universally superior; qualification depends on the ore and the receiving ironmaking process.
An additive calculation that prevents a common error
Illustrative calculation
For 91 t/h dry concentrate, a hypothetical trial dosage of 0.5% of dry concentrate requires 0.455 t/h additive. Applying 0.5% to 100 t/h wet concentrate would deliver 0.500 t/h, about 9.9% more additive than intended. These figures illustrate denominator control and are not a recommended binder dose.
Document whether additions enter the numerator of reported dry product mass. For trial comparisons, record delivered mass, calibration checks and batch identity; nominal feeder settings are not equivalent to measured consumption.
Technical references
Kawatra & Claremboux — Iron Ore Pelletization, Part I: Fundamentals — abstract/reference ↗
Kawatra & Claremboux — Iron Ore Pelletization, Part II: Inorganic Binders — abstract/reference ↗
Claremboux & Kawatra — Iron Ore Pelletization, Part III: Organic Binders — abstract/reference ↗
References support the underlying principles. Diagnostic sequences, worked examples and procurement questions are original engineering analysis; they are not plant operating instructions or verified supplier performance results.
Keep recipe chemistry and mixing performance separate
A change in strength may reflect a change in binder dispersion or water distribution rather than a change in nominal dosage. Check feeder calibration and concentrate moisture before attributing a result to the binder itself. Evaluate the resulting green, dry and fired properties together.