Sulphur-bentonite fertilizer is made by mixing bentonite into molten sulphur, at roughly 90 parts sulphur to 10 parts bentonite, and forming pastilles or granules. In soil, the bentonite swells and breaks the sulphur into fine particles that plants and soil bacteria can use.
Technical Specifications
Sodium vs calcium bentonite: which do you need?
Sodium bentonite swells many times its size in water and forms a seal or gel; calcium bentonite barely swells and is valued as an absorbent carrier. That one property decides who buys each grade. This page covers sodium bentonite.
| Sodium bentonite | Calcium bentonite | |
|---|---|---|
| Key behaviour | Swells strongly, forms gel and low-permeability seal | Low swell, high absorbency, holds liquids |
| Granule uses | Pond, lake and canal sealing; borehole and well annulus sealing; landfill and geosynthetic clay liners; clumping cat litter | Carrier granules for pesticides, bio-fertilizers and micronutrients (10x20, 16x35 mesh); soil conditioner; non-clumping litter; oil and spill absorbent |
| Powder uses | Drilling mud (oil, water well, HDD); iron ore pelletizing binder (75 micron); foundry green sand; sulphur-bentonite fertilizer (90:10); diaphragm wall and piling slurry; wine and juice fining | Fertilizer granulation binder; bleaching earth after acid activation (edible oil refining); ceramics; cosmetics and face packs |
| Main buyers | Drilling contractors, steel and pellet plants, foundries, cat litter brands, pond and landfill contractors, GCL makers, sulphur fertilizer makers | Agrochemical and bio-fertilizer formulators, NPK plants, oil refineries, ceramic and cosmetic makers |
| Tests buyers ask for | Swell index (ml/2g), gel/viscosity, fluid loss, moisture, mesh | Absorption (oil/water), crush strength, mesh, moisture, pH, dust |
Much “sodium bentonite” sold in India is calcium bentonite treated with soda ash (activated sodium). Ask for the swell index (ml/2g) and whether a grade is natural or activated before you order.
Read the full guide: sodium vs calcium bentonite powderRequest a Quote
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For: Bentonite for Sulphur-Bentonite Fertilizer
Who this is for
Sulphur-bentonite fertilizer plants and fertilizer brands that make their own pastille product, including plants in Gujarat, Rajasthan and Madhya Pradesh. Buyers usually trial the bentonite in their melt before agreeing a monthly quantity.
What the plant needs from the bentonite
High swell, so the pastille disperses fully when wetted in the soil; fineness, so the bentonite mixes into molten sulphur without gritty particles; and low moisture, because water in molten sulphur is a hazard. Ask for swell index, fineness and moisture, and for the test method behind each.
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View full categoryFrequently Asked Questions
Why does the bentonite need to be sodium?
Calcium bentonite swells too little to break the pastille apart. High-swell sodium bentonite does.
What moisture should the bentonite have?
Low enough for safe mixing into molten sulphur. Our powder is below 10% moisture on the product sheet; the limit your plant needs is [TBC: moisture limit for sulphur melt].
Where is the technical guide?
In our blog: bentonite as the disintegrating agent in sulphur-bentonite fertilizer.