About Fertiliser Binder Grade Bentonite
Fertiliser binder grade bentonite is a swelling clay used to bind and condition granular fertilisers. Mixed into the feed of a granulator, it improves plasticity so that fines agglomerate into round, uniform granules, and it adds crush strength once the granules are dried. The result is less breakage and dust during handling, storage, blending and spreading.
The same swelling property is central to sulphur bentonite products. Fine bentonite dispersed in molten sulphur and formed into pastilles absorbs soil moisture after application, swells and breaks each pastille apart into fine sulphur particles, which are then available for oxidation in the soil. The grade is also used in the granulation of NPK, micronutrient and organic-based fertilisers.
We supply this grade as a fine powder with controlled moisture, so it blends evenly with fertiliser feed or sulphur melt and does not add excess water to the process. Each batch is tested for swell index, moisture and fineness in our NABL-accredited laboratory and shipped with a Certificate of Analysis, giving plant QC teams a clear basis for incoming inspection. Samples are available for granulation and pastille trials. Fertiliser rules differ by country, so customers should verify that the clay and the finished product meet local regulatory requirements before sale.
Typical specifications
| Parameter | Typical Value | Test Method |
|---|---|---|
| Swell index | 18–26 ml/2 g | ASTM D5890 |
| Montmorillonite content (methylene blue) | ≥ 70 % | Internal method |
| Moisture | ≤ 10 % | Internal method |
| Passing 75 µm | ≥ 90 % | Wet sieve, internal method |
| pH (5 % suspension) | 8.5–10.5 | Internal method |
| Colour | Cream to grey | Visual |
Typical values for guidance. Guaranteed limits are stated on the Technical Data Sheet and batch CoA.
Key features & benefits
Effective granulation binder
Montmorillonite platelets bridge between fine particles in the granulator, helping fertiliser feed form round granules of consistent size with less recycle of undersize and oversize material.
Improved granule strength
Once dried, the clay adds crush strength to granules, which reduces breakage and dust in conveyors, storage piles, bulk blending and mechanical spreading equipment on the farm.
Swell-driven disintegration
In sulphur bentonite pastilles, the clay absorbs soil moisture and swells, breaking the pastille into fine sulphur particles. Fine grind and good swell are what make this work.
Low, controlled moisture
Moisture is typically held at 10 % or below, so the binder does not upset the water balance of the granulator or introduce moisture into a sulphur melt.
Applications
Sulphur bentonite pastilles
Fine bentonite dispersed in molten sulphur and pastillated or prilled, giving a degradable sulphur fertiliser that is easier and less dusty to handle than elemental sulphur powder.
NPK and compound granulation
Binder and conditioning aid in drum and pan granulation of compound fertilisers, helping fines agglomerate and improving the size distribution and physical quality of finished granules.
Micronutrient and organic granules
Used to bind micronutrient blends and organic-based fertiliser granules into a durable, spreadable form, subject to local regulatory approval of the finished product in each market.
Usage & handling
- Granulation binder: typical additions are around 2–5 % of dry feed mass, adjusted to granule strength targets.
- Sulphur bentonite: formulations commonly use about 10 % bentonite in the sulphur melt; confirm the ratio in your own process.
- Blend the bentonite with dry feed before water or steam is added so it is evenly distributed.
- Store in sealed bags in a dry area; absorbed moisture causes lumps that disperse poorly in sulphur melt.
Packaging & supply
- 25 kg and 50 kg HDPE or paper bags
- 1 MT and 1.2 MT jumbo (FIBC) bags for fertiliser plants
- Custom or private-label packaging on request
Frequently asked questions
How does bentonite work in sulphur bentonite fertiliser?
Fine bentonite is dispersed in molten sulphur, which is then formed into pastilles or prills. After application, the bentonite absorbs moisture from the soil and swells. That swelling breaks the pastille into fine sulphur particles with a much larger surface area, which soil microorganisms can then oxidise. Good swell and fine particle size are the binder properties that matter most.
What addition rate is used for bentonite as a granulation binder?
Typical additions are around 2–5 % of dry feed mass, depending on the fertiliser chemistry, granulation method and the granule strength you need. Plants normally optimise the rate in trials, measuring crush strength, size distribution and dust. We can supply samples and a Technical Data Sheet to support your trials and help find the lowest effective dosage.
Does bentonite binder dilute fertiliser nutrient content?
Yes. Bentonite is a carrier and binder rather than a nutrient source in the declared analysis, so its addition rate must be accounted for when formulating to a guaranteed nutrient content. In most granulation uses the addition is small. In sulphur bentonite, the bentonite share is set to balance pastille breakdown against sulphur content.
Is fertiliser binder grade bentonite approved for fertiliser use?
Bentonite is widely used as a binder and carrier in fertilisers, but approval rules differ by country and by product type. We supply the clay with its Technical Data Sheet, MSDS and batch Certificate of Analysis to support your registration. Customers should verify suitability and confirm local regulatory approval for the finished fertiliser before sale.