Screening & feeding
Connect size separation with the material delivered to induration.
What happens here
Green-pellet screening separates off-size material from the stream sent to thermal treatment. Feeding arrangements must also consider the distribution and handling of that material.
Equipment in this stage
Roller screens, feeders and distribution conveyors.
Inputs to define
Separation duty; feed variability; stream destinations; transfer interfaces; access and maintenance.
A useful review question
A screen result and the condition of material at the furnace inlet are not necessarily the same observation. Identify both measurement points.
Continue to the practical guide ↗A screen has three outcomes, not one efficiency number
For a three-product duty, measure undersize reject, accepted product and oversize reject separately. Good undersize removal can coincide with excessive rejection of usable pellets. Good product cleanliness can also be achieved by rejecting too much material. A useful acceptance test therefore states both contamination limits and recovery objectives.
Research on roller-screen classification uses material and contact calibration before simulation. This is relevant because green pellets are deformable material, not rigid calibration spheres. A nominal roll gap is a mechanical setting; the realised separation is a measured distribution.
Locate the fault with matched samples
| Location | Observation | Interpretation |
|---|---|---|
| Screen inlet | Size, moisture, pellet integrity and distribution across width | Defines the actual screening task. |
| Each outlet | Mass flow and size distribution over the same period | Separates removal efficiency from loss of usable pellets. |
| After transfer to furnace feed | New fines and widthwise distribution | Identifies degradation or segregation after classification. |
| Roll bank, safely isolated | Gap map, buildup, wear and alignment | Tests mechanical consistency against the observed result. |
Sampling must follow the plant’s safe procedure. Never approach moving rolls or reach into an operating screen to obtain a sample or measure a gap. Use designated sampling points, and isolate machinery before physical inspection.
Connect classification with the bed entering induration
The first screen does not define the final burden. Subsequent drops, feed chutes, distribution conveyors and levelling can change the material presented to the furnace. Track the last controllable transfer as part of the screening project, particularly when the proposed benefit depends on burden uniformity.
Read the roller-screen performance guide, with a worked mass balance →
Technical references
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.
Specify the complete feed path
A cleaner screen outlet is valuable only if later transfers preserve the improvement. Measure degradation and distribution between screening and furnace charging. Where a design proposes deliberate size layering, verify the final bed arrangement and its relationship to the thermal profile.