Calcium lignosulfonate is a water-soluble binder for fertilizer granules: compound NPK, organic-mineral blends, micronutrient granules and soil-input pellets. It helps fines agglomerate, strengthens dried granules and reduces dust. This page covers how it works, how to run a granulation trial and which measurements decide the dosage.
- Role: binder and anti-dust aid in drum, pan and compaction granulation.
- Form: powder dissolved in the granulation liquid, or liquid sprayed directly.
- Dosage: set by trial on a dry-solids basis; no universal rate.
- Limits: water-soluble binder; adds some calcium, sulfate and sugar.
How It Binds Fertilizer Granules
In wet granulation, the binder solution wets fine particles and forms liquid bridges between them. As the granules dry, the dissolved lignosulfonate turns into solid bridges that hold the particles together. The result is stronger granules with fewer fines. Because the binder stays water-soluble, the granules still break down in moist soil.
Where It Is Used
| Product | Binder role | Watch for |
|---|---|---|
| Compound NPK granules | Strength and lower dust | Calcium reacting with phosphate in the slurry |
| Organic-mineral blends | Holds organic and mineral fines together | Moisture balance of organic fractions |
| Micronutrient granules | Binder plus complexing of metal ions | pH and metal compatibility |
| Soil-input pellets and coated granules | Binder or coating component | Dissolution rate; see coated fertilizers |
Running a Granulation Trial
- Record the baseline: formulation, moisture, recycle ratio, dryer temperatures and current granule quality.
- Dissolve the powder in the granulation water or use a liquid grade; state the addition on a dry-solids basis.
- Test three or four additions plus a no-binder control, changing nothing else.
- Measure crushing strength, attrition (fines after tumbling), size distribution, final moisture and caking after storage.
- Pick the lowest addition that meets targets, then confirm at plant scale.
What to Measure
| Measurement | Why |
|---|---|
| Granule crushing strength | Survives handling and bulk storage |
| Attrition and dust | Fines lost in transport and spreading |
| Size distribution and recycle ratio | Plant throughput and spreading quality |
| Final moisture and caking | Storage behaviour in bags and bulk |
| Dissolution | Nutrient release in soil |
Agricultural Grade for Granulation
| Parameter | GAC-CaLS-AGRI (TDS Rev. 2.0) |
|---|---|
| Appearance | Yellow-brown powder |
| Lignosulfonate content | 60% min (dry basis) |
| Dry matter / moisture | 95% min / 5% max |
| Water-insoluble matter | 0.2% max |
| pH | 4–7 |
| Total calcium and magnesium (as sulfate) | 5–6% |
| Sulphate | About 5% |
| Sugar | 15% |
| Total NPK | About 10% |
Typical values from the current TDS. Each lot ships with a COA.
Feed-pellet binders are a different application with feed-specific rules; see lignosulfonate pellet binder for feed. Slow-release coatings are covered in lignosulfonate-coated slow-release fertilizers.
Grades for Granulation
| Grade | Key data (TDS) | Note |
|---|---|---|
| CaLS Agri (GAC-CaLS-AGRI) | Lignosulphonate 60% min; insolubles 0.2% max; sugar 15% | Sugar adds tack in granulation |
| CaLS Grade One (GAC-CaLS-1) | Lignosulphonate 55% min; insolubles 1.5% max | TDS lists binder use for powders and pellets |
| NaLS Binder (GAC-NaLS-Binder) | Lignosulphonate 55% min; Ca + Mg 0.5% max | Choose where extra calcium is unwanted |
Common Granulation Problems
| Problem | What to check |
|---|---|
| Weak granules | Binder level, granulation moisture, drying temperature |
| Too many fines | Binder distribution and recycle ratio |
| Sticky granules or caking | Residual moisture and storage humidity |
| Phosphate reaction | Calcium grade with phosphate: test a sodium grade |
FAQ
How does calcium lignosulfonate bind fertilizer granules?
Dissolved in the granulation liquid, it coats fine particles and dries to a film that holds them together, raising granule strength and reducing dust.
How much should I add?
There is no universal rate for fertilizers. Run a trial ladder of three or four additions on a dry-solids basis against a no-binder control, and pick the lowest level that meets strength and dust targets.
Powder or liquid for granulation?
Liquid suits spraying into a drum or pan; powder can be dissolved on site or dry-blended. Compare on a dry-solids basis.
Does it make granules water-resistant?
No. Lignosulfonate is water-soluble, so granules dissolve normally in soil water. Caking in storage depends on moisture, so check final granule moisture.
What is a lignin sulfonate pellet binder?
Lignosulfonate (lignin sulfonate) used to bind fertilizer or feed pellets; it forms solid bridges between particles as the pellet dries.
Calcium or sodium lignosulfonate for granulation?
Both are used; choose sodium where extra calcium could react with phosphate, and confirm by trial.
Grades and Documents
Related: fertilizer formulation and testing · properties for fertilizers and soil
