Lignosulfonate is a water-soluble material derived from lignin, recovered as a byproduct of the sulfite pulping process. Its adhesive properties make it a widely used binder for compacting fine mineral and metal powders into pellets or briquettes before further processing.
Role as a binder in pelletizing and briquetting
Lignosulfonate’s most well-established use in this area is as a binder for iron ore pellets and coke breeze briquettes in the metallurgical and mining industries, where it helps bind fine powder into a stable, handleable form before further processing such as sintering, smelting, or combustion. General functions include:
- Binding: Lignosulfonate’s adhesive properties help hold fine powder particles together, forming a cohesive “green” (unfired or uncured) pellet or briquette.
- Processing aid: It can help reduce friction during compaction or pressing, supporting more consistent shaping with less equipment wear.
- Clean burn-off: During subsequent high-temperature processing (such as sintering or combustion), lignosulfonate generally decomposes and burns off, leaving minimal residue.
General process considerations
A typical pelletizing or briquetting process using lignosulfonate as a binder involves mixing the binder with the powder material, adjusting moisture content, forming the mixture into pellets or balls (by pressing or rolling), and then drying or curing — either in a dryer at an elevated temperature or through natural air drying. Binder dosage, moisture content, forming method, and drying conditions must be determined for the specific powder material (such as iron ore fines or coke breeze) and equipment being used — they are not interchangeable between different materials, and published dosage figures or process parameters from one operation should not be assumed to apply directly to another without trial validation.
Advantages
- Renewable and biodegradable, compared with petroleum-based synthetic binder alternatives.
- Cost-effective, since it is recovered as a byproduct of pulping rather than purpose-synthesized.
For applications involving precision powder-metallurgy parts (such as sintered gears or bearings) rather than bulk ore or coke pelletizing, binder selection, dosage, and sintering behavior should be validated specifically for the target metal powder and part specification, since performance requirements differ significantly from bulk ore or coke pelletizing applications.
