Seven grades from one supplier
Drilling, foundry, pelletizing, sealing, filler and fertiliser binder grades from our Gujarat and Rajasthan locations, backed by 25,000+ MTPA of manufacturing capacity across 5+ sites.
Industrial Mineral
Bentonite — Manufacturer & Exporter from India
Sodium, calcium, API 13A drilling, foundry, pelletizing and fertiliser binder grades of bentonite, processed in Gujarat and Rajasthan and tested batch by batch.
PowderGranulesPelletsActivated Grade
ISO 9001 certified processes
NABL-accredited lab testing
CoA, TDS & MSDS with every shipment
Export packaging worldwide
Overview
What is Bentonite?
Bentonite is a natural clay made up mainly of montmorillonite, a smectite mineral with a layered alumino-silicate structure. Each platelet carries a negative surface charge balanced by exchangeable sodium or calcium ions, and water enters readily between the layers. That structure gives bentonite its defining behaviour: it swells, binds, absorbs and forms thixotropic gels that thin under shear and rebuild at rest.
Bentonite deposits form over geological time from the alteration of volcanic ash and tuff. The character of each deposit depends on its dominant exchangeable cation. Sodium bentonite swells strongly and builds viscosity at low dosage. Calcium bentonite swells less but offers good absorbency, adsorption and plasticity. Where an application needs sodium-type performance, calcium ore can be converted by controlled soda-ash activation.
These properties make bentonite a working material in many industries. It suspends cuttings and builds filter cake in drilling fluids, bonds silica sand in green sand moulds, holds iron ore concentrate together in pellets and binds fertiliser granules. It also seals ponds, landfills and diaphragm wall trenches, and acts as a filler, absorbent and carrier in agricultural and industrial formulations.
Obsidian Minerals processes bentonite at manufacturing locations in Gujarat and Rajasthan. Ore is selected by deposit and tested before processing, then dried, activated where the grade requires it, ground and classified to specification. Our NABL-accredited laboratory measures swell index, rheology, filtrate and fineness to the relevant method, and every shipment travels with a Technical Data Sheet, MSDS and batch Certificate of Analysis. We supply seven standard grades in powder, granule and pellet forms, and develop custom grades and particle sizes with customers who need something specific.
Bentonite grades
Select a grade for its typical properties, applications, usage guidance and FAQs.
Bentonite
Sodium Bentonite
High-swelling sodium bentonite that hydrates into a low-permeability seal for liners, ponds, slurry walls and containment works.
Sealing and Environmental Applications BentoniteCalcium Bentonite
Moderate-swell calcium bentonite with good absorbency and adsorption, used as a filler, carrier and absorbent in industrial and agricultural formulations.
Filler, Absorbent, Carrier BentoniteAPI 13A Sec. 9 Bentonite
Sodium drilling bentonite tested against API 13A Section 9 limits for dial reading, YP/PV ratio, filtrate volume and coarse residue.
Drilling Fluids BentoniteOCMA-Grade Bentonite
Finely ground OCMA-grade drilling bentonite tested to API 13A Section 11, with residue above 75 µm held at 2.5 % or less.
Drilling Fluids BentoniteFoundry Grade Bentonite
High-swelling foundry bentonite that bonds silica sand into strong, permeable green sand moulds for ferrous and non-ferrous castings.
Green Sand Mold Strength BentonitePelletizing Grade Bentonite
Fine, high-swelling bentonite binder that gives iron ore green pellets the strength to survive balling, handling and induration.
Iron Ore Pellet Production BentoniteFertiliser Binder Bentonite
Fine swelling bentonite that binds fertiliser granules and helps sulphur bentonite pastilles break down once applied to moist soil.
Agriculture| Grade | Specification | Primary use | Link |
|---|---|---|---|
| Sodium Bentonite | On TDS | Sealing and Environmental Applications | Specs |
| Calcium Bentonite | On TDS | Filler, Absorbent, Carrier | Specs |
| API 13A Section 9 Drilling Grade Bentonite | API 13A Section 9 | Drilling Fluids | Specs |
| API 13A Section 11 OCMA-Grade Bentonite | API 13A Section 11 | Drilling Fluids | Specs |
| Foundry Grade Bentonite | On TDS | Green Sand Mold Strength | Specs |
| Pelletizing Grade Bentonite | On TDS | Iron Ore Pellet Production | Specs |
| Fertiliser Binder Grade Bentonite | On TDS | Agriculture | Specs |
From deposit to dispatch
- 01
Selective mining and ore grading
- 02
Drying to controlled moisture
- 03
Soda-ash activation where the grade requires it
- 04
Grinding and air classification
- 05
Laboratory QC and packing
Why source Bentonite from Obsidian Minerals
Tested where it matters
Swell index, rheology, filtrate and residue are measured in our NABL-accredited laboratory under ISO 9001 certified processes, with results on every batch CoA.
Export-ready supply
Shipped to 15+ countries in 25 kg or 50 kg bags or 1 MT and 1.2 MT jumbo bags, with MSDS and Technical Data Sheet supplied.
Where Bentonite is used
Bentonite — frequently asked questions
What is the difference between sodium and calcium bentonite?
Sodium bentonite has sodium as its main exchangeable cation, so it swells strongly, builds viscosity and forms low-permeability seals. It is used in drilling fluids, liners, foundry sand and pellet binding. Calcium bentonite swells much less but absorbs well and has useful plasticity, which suits filler, carrier, ceramic and absorbent uses. Calcium bentonite can be soda-ash activated to give sodium-type behaviour where that is needed.
Which bentonite grade should I choose for drilling mud?
Choose the grade your mud programme or tender names. API 13A Section 9 bentonite has the tighter rheology and filtrate limits and is the usual choice when a programme simply asks for API bentonite. Section 11 OCMA-grade bentonite permits a higher YP/PV ratio and filtrate but has a stricter limit on residue above 75 µm. We supply both and can send samples for testing.
What tests are reported on your bentonite Certificate of Analysis?
The CoA reports the parameters that define each grade. Drilling grades show 600 r/min dial reading, YP/PV ratio, filtrate volume and residue above 75 µm. Sealing, foundry, pelletizing and binder grades typically show swell index, moisture, fineness and grade-specific tests such as fluid loss or plate water absorption. Testing is carried out in our NABL-accredited laboratory, and guaranteed limits are stated on the Technical Data Sheet.
What packaging is available for bulk bentonite?
Bentonite is packed in 25 kg or 50 kg HDPE or paper bags, or in 1 MT and 1.2 MT jumbo (FIBC) bags for plants that discharge directly into silos or mixers. Custom and private-label packaging is available on request. Each shipment is supplied with an MSDS, Technical Data Sheet and batch Certificate of Analysis, so your receiving and QC teams have the documents they need.
Can I get a bentonite sample before placing an order?
Yes. Samples are available on request for every grade, so you can run your own laboratory or plant trials before committing to volume. Tell us the application, the specification you work to and any test method you prefer, and we will send a representative sample with its Technical Data Sheet. If a standard grade is not a close fit, we can develop a custom grade with you.
Do you supply activated bentonite?
Yes. Where a grade needs sodium-type swelling and viscosity, we activate the clay with a controlled soda-ash treatment during processing. Activation is used selectively, depending on the deposit and the target specification for the grade. If your process calls for a specific activation level, swell index or rheology profile, share the requirement and we will confirm the most suitable grade or develop a custom one.
Do you provide MSDS and technical datasheets?
Yes. A Technical Data Sheet and MSDS are available for every grade, and each shipment is accompanied by a batch-specific Certificate of Analysis.
Request a quote
Interested in Bentonite?
Tell us your application, preferred grade and volume. Our engineering team will recommend the right grade and send a datasheet, sample and quotation.
- Technical Data Sheet & MSDS
- Samples for qualification trials
- Bulk and recurring supply pricing