Balling
Understand the role of discs and drums in forming unfired pellets.
What happens here
Balling discs or drums agglomerate prepared fine material into green pellets. The resulting material must meet the next process stage’s requirements and survive transfer.
Equipment in this stage
Pelletizing discs and balling drums.
Inputs to define
Feed conditions; size distribution; recycle streams; available operating controls; green-pellet handling.
A useful review question
Distinguish fresh feed from total circulating load. Define where samples are taken before comparing equipment performance.
Continue to the practical guide ↗Read the circulating material, not only the disc speed
A balling circuit receives prepared feed and may also receive return material. The returning stream carries its own particle sizes, moisture and recent processing history. When recycle rises, a machine can handle more internal tonnage while exporting the same or less on-size product. Monitor fresh feed, total circuit load and accepted product as three different quantities.
Disc inclination, rotational speed, feed location, water distribution and scraper condition form an interacting set of variables. Changing several together may improve a result but obscures its cause. For a diagnostic campaign, first stabilise the feed, then change one controllable factor within the equipment supplier’s approved range. Record the time required for the circuit to settle.
Disc or drum: compare a complete circuit
A disc presents an accessible rolling bed and adjustable geometry; a drum presents a different residence and recycle arrangement. Compare the layout and classification circuit as well as the balling machine. Required operating range, maintenance access, water control, plant redundancy and ore testwork should drive the decision.
| Symptom | Evidence to collect | Avoid assuming |
|---|---|---|
| More oversized green pellets | Full size distribution, water delivery and feed-rate history | That lowering one speed setting will always solve it. |
| More fines after transfer | Samples before and after the transfer | That every fine was created in the balling machine. |
| Increasing recycle with stable new feed | Screen outlet flows and screen partition by size | That recycle is always evidence of poor balling. |
| Different behaviour between parallel discs | Matched feed, calibration and geometry records | That identical setpoints imply identical material conditions. |
Measure the economics at the circuit boundary
A practical comparison tracks on-size green product per tonne of new dry feed, electricity per tonne of exported product, water addition, maintenance hours and the range of product size. An increase in gross throughput is useful only if it improves the export that the downstream plant can use. Include enough operating time to distinguish a stable change from a transient release of material inventory.
Read the detailed guide to balling-disc control and recycle →
Technical references
CVIC — pelletizing discs (supplier technical 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.
Watch growth, deformation and accepted-size yield together
Green-pellet formation involves seed formation, layering and coalescence alongside breakage and abrasion. Excessive growth can increase oversize return; greater plasticity can improve a drop result while creating deformation during handling. Diagnose the circuit using size distributions and material condition at more than one location.