Sodium lignosulfonate is produced from the spent liquor of sulfite pulping. The liquor contains dissolved lignosulfonate, wood sugars and inorganic salts; refining turns it into a consistent powder or liquid grade.
From Spent Liquor to Powder
- Collect spent sulfite liquor after the pulp has been separated.
- Convert to the sodium salt if the mill cooks with calcium: the calcium is exchanged for sodium and removed as an insoluble calcium salt. This gives the low Ca + Mg that sodium grades are specified for.
- Reduce sugars where needed, for example by fermentation, because sugars retard cement setting.
- Concentrate by evaporation to a liquid grade.
- Spray-dry to a free-flowing powder.
How Production Shows Up in the Specification
| Parameter | Sodium LS Grade One (GAC-NaLS-1) | Why it matters |
|---|---|---|
| Lignosulfonate content | 55% min (dry basis) | Active material |
| Calcium & magnesium | 0.5% max | Shows the sodium conversion; matters in sulfate- or phosphate-rich systems |
| Reducing sugar | 7% max | Affects concrete setting time |
| Water-insoluble matter | 1.5% max | Fibres and impurities |
| Sulphate | 2–5% | Inorganic salt from processing |
| Moisture | 5% max | Drying quality |
Liquid sodium lignosulfonate (for example our dust-control grade, 45% min solids) skips the drying step. Product details: sodium lignosulfonate. Background: from lignin to lignosulfonate.
Powder or Liquid?
| Powder | Liquid | |
|---|---|---|
| Solids | About 95% dry matter | About 45–50% solids |
| Handling | Bags; dissolve before use | Pump directly; protect from freezing |
| Transport cost per unit of active | Lower | Higher (water is shipped) |
| Typical buyers | Export, dry-mix plants | Local plants with tank storage |
Both forms come from the same refined liquor; the choice depends on your dosing equipment and freight.
Frequently Asked Questions
How is sodium lignosulfonate made?
From spent sulfite pulping liquor: the lignosulfonate is converted to the sodium salt if needed, sugars are reduced, and the liquor is concentrated and spray-dried.
Why does sodium lignosulfonate have low calcium and magnesium?
Calcium is removed when the liquor is converted to the sodium salt. Our Grade One specifies Ca + Mg at 0.5% max.
