Bentonite
Bentonite is a clay formed from altered volcanic ash, dominated by the swelling mineral montmorillonite. Put in water it takes up many times its own volume, builds a gel and holds fine solids in suspension, and that single behaviour is what every use rests on. Sodium bentonite is the swelling type and it goes into drilling fluid, into slurry walls and grouting, into geosynthetic clay liners for landfill, and into the binder that holds an iron ore pellet together on its way to the furnace. Calcium bentonite swells less and works as an adsorbent, a bleaching earth for edible oil refining, a foundry sand binder, a cat litter and a carrier for animal feed. Acid activated grades are used to decolourise oils and to clarify wine and juice.
Listed bentonite markets
Each line is a grade at a delivery point. Open one for its full specification and terms.
Grades
A bentonite contract turns on the exchangeable cation, on the rheology the clay develops in water, and on the physical test that matches the intended use. Drilling, foundry, pelletising and bleaching grades are tested in different ways and one certificate does not serve the other.
Chemical assay
10 grades
| Grade | Definition |
|---|---|
| Exchangeable cationDeclared, as sodium, calcium or activated | The governing distinction in the trade. Sodium bentonite swells, calcium bentonite adsorbs, and sodium activated material is calcium clay treated with soda ash. |
| Montmorillonite contentPercentage by mass | Determined by X-ray diffraction or inferred from the cation exchange capacity. It is the active mineral and the rest is ballast. |
| Cation exchange capacityMilliequivalents per hundred grams | Determined by the methylene blue or ammonium acetate method. It is the most direct measure of the clay activity. |
| Methylene blue valueGrams per hundred grams | Determined by titration. Fast, reproducible and used as the working proxy for active clay at the plant gate. |
| Silica and aluminaPercentage by mass | Determined by X-ray fluorescence on a fused bead under ISO 12677, reported as the oxide. |
| Iron as ferric oxidePercentage by mass | Determined by X-ray fluorescence. It governs the colour of the clay and matters for bleaching earth and for pale filler use. |
| Calcium and magnesium oxidePercentage by mass | Reported because they indicate the calcium fraction and the carbonate carried with the deposit. |
| Alkali content as sodium oxidePercentage by mass | Distinguishes natural sodium clay from soda ash activated material, and it is a contract term where the buyer specifies natural. |
| pH of the aqueous suspensionpH units | Measured on a suspension at the stated solids loading under ISO 787. |
| Loss on ignitionPercentage by mass | Determined at the stated temperature. It captures structural water, carbonate and organic matter. |
Physical properties
11 grades
| Grade | Definition |
|---|---|
| Swelling indexMillilitres per two grams in water | Measured in a graduated cylinder over a fixed settling period. It is the defining test for a sodium bentonite. |
| YieldCubic metres of drilling fluid of the stated viscosity, per tonne | Determined under the drilling fluid materials specification. It is the commercial unit of a drilling grade clay. |
| Apparent and plastic viscosityMillipascal seconds | Measured on a suspension at the specified solids loading on a rotational viscometer under the drilling fluid materials specification. |
| Yield point to plastic viscosity ratioDimensionless | Governs how well the fluid lifts cuttings. It is the working rheology term on a drilling contract. |
| Filtrate lossMillilitres over the stated period at the stated pressure | Measured in a filter press. It governs the quality of the filter cake the clay builds against the formation. |
| Free swellMillilitres per two grams | Reported for liner and grouting grades, alongside the fluid loss of the compacted clay. |
| Green and dry compression strengthKilopascals | Measured on a rammed sand specimen for foundry grade clay, with the sand and the moisture stated. |
| Hot and wet tensile strengthKilopascals | Foundry terms measuring how the mould behaves as the metal front arrives. |
| Green pellet drop number and compressive strengthDrops, and newtons per pellet | The pelletising binder terms. They govern whether the green pellet survives the transfer to the induration furnace. |
| Bleaching efficiencyReported as the residual colour of a standard oil after treatment at the stated dosage | The test for bleaching earth. It is run on the buyer own oil wherever possible, because performance is oil specific. |
| MoisturePercentage by mass, maximum | Determined by oven drying. It affects the shipped weight, the flow in the silo and the shelf life of activated grades. |
Particle size and sizing
5 grades
| Grade | Definition |
|---|---|
| Residue on the fine sievePercentage by mass, maximum, at the stated aperture | Determined by wet sieving on a sieve conforming to ISO 3310. Grit is the defect in a milled clay. |
| GrindDeclared, as the named milled or granular cut | Powdered to a stated screen, granular for feed and litter, or crumbed for civil works. The cut is contracted. |
| Particle size distributionMicrometres, by percentile | Determined by laser diffraction under ISO 13320 where the fine tail matters. |
| Bulk density, loose and tappedKilograms per cubic metre | Sets the silo, the bag and the freight cube. |
| Dust and attritionReported against the named method | For granular grades, how much fine material the product makes in handling. |
Contaminants and regulated substances
5 grades
| Grade | Definition |
|---|---|
| Crystalline silicaPercentage by mass | Quartz and cristobalite in the clay, declared on the safety data sheet and controlled where the material is used in food or feed. |
| Heavy metalsMilligrams per kilogram, maximum, by element | Arsenic, lead, cadmium and mercury, determined on a digest against the food, feed or pharmacopoeial limit at the destination. |
| Dioxins and dioxin like compoundsPicograms of toxic equivalent per kilogram, maximum | Tested for feed grade and food contact clay, where the regulation sets a limit on the mineral itself. |
| Pharmacopoeial identity and purityPass or fail, against the named monograph | For pharmaceutical grade clay, the identification, swelling power, microbial and elemental impurity tests of the monograph in force at the destination. |
| Microbiological limitsColony forming units per gram, maximum | For feed, food and pharmaceutical grades, against the destination specification. |
Delivery, documentation and certification
9 grades
| Grade | Definition |
|---|---|
| Form and packingDeclared | Bulk, big bags of a stated net weight, paper or polywoven bags palletised and shrink wrapped, or containerised bulk in liners. The pack is a price term because it drives the handling cost at both ends. |
| Moisture at loadingPercentage by mass, maximum | Determined by oven drying on a loading sample. Moisture is paid for as mineral unless the contract sets a dry weight basis, so it is always specified. |
| Weight basisDeclared | Wet or dry metric tonnes, on shipped weight or landed weight, with the survey house named and the draft survey or weighbridge method stated. |
| Sampling and assay protocolDeclared | Who samples, at which point, to what standard, how the sample is split and sealed, and which laboratory umpires a dispute. It is agreed before loading, not after. |
| Transportable moisture limitPercentage by mass | Where the cargo is a group A material under the maritime bulk cargoes code, the flow moisture point and the transportable moisture limit are certified before loading. |
| Safety data sheetDocument, to the globally harmonised system format | Classification, handling and respirable crystalline silica statement, supplied with every consignment. |
| Certificate of analysisDocument, per lot | Issued by the named laboratory against the contract specification, referencing the lot and the sampling record. |
| Regulatory registrationDeclared | Chemical registration at the destination where the mineral requires one, named on the contract. |
| Origin and due diligenceDeclared, with the mine or plant named | Country of origin, the mine or processing plant, and where required the responsible sourcing statement. |
Grades outside this list trade on request. Send us the contract specification you work to and we will price against it.
Locations
| Country | Region | We trade it as |
|---|---|---|
| United States | North America | Origin and destination |
| Turkiye | Europe and Anatolia | Origin and destination |
| Greece | Southern Europe | Origin and destination |
| India | South Asia | Origin and destination |
| China | East Asia | Origin and destination |
| Mexico | North America | Origin and destination |
| Russian Federation | Eurasia | Origin and destination |
| Ukraine | Eastern Europe | Origin and destination |
| Italy | Southern Europe | Origin and destination |
| Spain | Southern Europe | Origin and destination |
| Germany | Western Europe | Destination |
| Bulgaria | Southeast Europe | Origin and destination |
| Romania | Southeast Europe | Origin and destination |
| Czechia | Central Europe | Origin and destination |
| Poland | Central Europe | Origin and destination |
| United Kingdom | Northern Europe | Origin and destination |
| France | Western Europe | Origin and destination |
| Netherlands | Northwest Europe | Destination and trading hub |
| Belgium | Northwest Europe | Destination |
| Morocco | North Africa | Origin and destination |
| Tunisia | North Africa | Origin and destination |
| Algeria | North Africa | Origin and destination |
| Egypt | North Africa | Origin and destination |
| South Africa | Southern Africa | Origin and destination |
| Kenya | East Africa | Origin and destination |
| Tanzania, United Republic of | East Africa | Origin and destination |
| Mozambique | Southern Africa | Origin and destination |
| Iran | Middle East | Origin and destination |
| Saudi Arabia | Middle East | Origin and destination |
| United Arab Emirates | Middle East | Destination and trading hub |
| Oman | Middle East | Origin and destination |
| Kazakhstan | Central Asia | Origin and destination |
| Japan | East Asia | Destination |
| Korea, Republic of | East Asia | Destination |
| Thailand | Southeast Asia | Origin and destination |
| Viet Nam | Southeast Asia | Origin and destination |
| Indonesia | Southeast Asia | Origin and destination |
| Malaysia | Southeast Asia | Origin and destination |
| Pakistan | South Asia | Origin and destination |
| Sri Lanka | South Asia | Origin and destination |
| Brazil | South America | Origin and destination |
| Argentina | South America | Origin and destination |
| Chile | South America | Origin and destination |
| Peru | South America | Origin and destination |
| Colombia | South America | Origin and destination |
| Canada | North America | Origin and destination |
| Australia | Oceania | Origin and destination |
| New Zealand | Oceania | Origin and destination |
| Singapore | Southeast Asia | Trading and finance |
| Switzerland | Western Europe | Trading and finance |
| Israel | Middle East | Origin and destination |
| Qatar | Middle East | Origin and destination |
| Nigeria | West Africa | Origin and destination |
Origins and destinations outside this list trade on request. We are not limited to the locations shown here.
Timing
Production is when the mineral is mined and processed at origin, which follows the mine plan and the weather at the pit rather than a crop season. Arrival is when a shipment from that origin typically lands in a consuming market. The gap between them is drying, grading, bagging and the voyage.
HarvestArrival
| Origin | J | F | M | A | M | J | J | A | S | O | N | D | Window |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| United States | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest Jan to Dec, arrival Jan to DecWyoming and Montana produce the benchmark natural sodium bentonite. Mining runs through the season and the mills hold stock for winter shipment. |
| Turkiye | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest Jan to Dec, arrival Jan to DecA major exporter of both calcium and activated clay, with bleaching earth and drilling grade plants serving Europe and the Middle East. |
| Greece | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest Jan to Dec, arrival Jan to DecMilos island production, shipped in bulk into the European pelletising, foundry and civil engineering markets. |
| India | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Arrival | Harvest | Harvest and arrival | Harvest and arrival | Harvest Oct to May, arrival Nov to JunKutch in Gujarat is the principal district, producing activated and natural clay. Mining slows through the monsoon. | |||
| China | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest Jan to Dec, arrival Jan to DecLarge domestic production across several provinces serving pelletising, foundry, litter and drilling demand, with an export programme in processed grades. |
| Mexico | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest Jan to Dec, arrival Jan to DecNorthern production supplying the North American foundry and drilling markets. |
| Russian Federation | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest Jan to Dec, arrival Jan to DecDomestic deposits supplying the pelletising and foundry industries, with overland movement into neighbouring markets. |
| Italy | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest Jan to Dec, arrival Jan to DecSardinian production and a processing sector converting domestic and imported clay into activated and specialty grades. |
Windows outside this pattern trade on request, including carry, forward positions and tonnage already sitting in a destination warehouse or terminal.
Customs, packing and contract terms
Indicative terms for bentonite. Tariff classification is the importer’s responsibility and limits change, so confirm both against the destination customs authority and the current regulation before you fix a contract.
- HS heading2508.10 Bentonite
- PackingBulk in a lined container, 1 t big bags, or 25 kg to 50 kg paper or PP bags on pallets. Moisture and particle size distribution stated on the certificate of analysis at load.
- Container loading20ft: 26 t to 28 t bulk or big bag. Weight limited well before volume. Check the road weight limit at the destination before fixing the box size.
- Contract and arbitrationSale on typical analysis with a certificate of analysis at load port and an umpire clause. ASTM and API specifications where they exist, including API 13A for drilling grade barite and bentonite. Arbitration under ICC rules or at the contract seat.
- Destination limitsEU REACH registration above one tonne per importer per year, respirable crystalline silica exposure controls under Directive 2017/2398, asbestos screening for talc and vermiculite, NORM screening on heavy mineral products, and food, pharmacopoeia or cosmetic grade certification where the end use requires it.
Common questions
What grades of bentonite does SIP Global trade?
We quote 40 published grades of bentonite, including Exchangeable cation - Declared, as sodium, calcium or activated, Montmorillonite content - Percentage by mass, Cation exchange capacity - Milliequivalents per hundred grams, Methylene blue value - Grams per hundred grams, Silica and alumina - Percentage by mass and Iron as ferric oxide - Percentage by mass. Every grade is tied to a delivery point and a settlement route. Grades outside the published list are priced on request.
How is bentonite graded?
A bentonite contract turns on the exchangeable cation, on the rheology the clay develops in water, and on the physical test that matches the intended use. Drilling, foundry, pelletising and bleaching grades are tested in different ways and one certificate does not serve the other. Grading runs on 5 systems: Chemical assay, Physical properties, Particle size and sizing, Contaminants and regulated substances and Delivery, documentation and certification.
Where does SIP Global trade bentonite?
We trade bentonite in United States, Turkiye, Greece, India, China, Mexico, Russian Federation and Ukraine and 45 further markets. Origins and destinations outside this list trade on request. We are not limited to the locations shown.
When is bentonite harvested and when does it arrive?
Typical windows are United States: harvest jan to dec, arrival jan to dec; Turkiye: harvest jan to dec, arrival jan to dec; Greece: harvest jan to dec, arrival jan to dec; India: harvest oct to may, arrival nov to jun; China: harvest jan to dec, arrival jan to dec. Harvest is when the lot is taken at origin, arrival is when a shipment from that origin lands in a consuming market. Windows outside this pattern, including carry, trade on request.
What is the HS code for bentonite?
Bentonite is normally classified under HS 2508.10 (bentonite). The heading follows the form the goods are in at the border, and national tariffs extend it beyond six digits, so confirm the full line with the destination customs authority before you fix a contract.
How do I get a price for bentonite?
Send the grade, the origin and the delivery window to the SIP Global desk. That is enough for a trader to come back with a level and a settlement route. 1 listed bentonite market is published on this page, each with its full specification and terms. We take both sides, physical and financial, prompt to long dated.
Standards and data sources
The grading language on this sheet follows published standards. Trade volumes and tariff lines are public record. Verify anything here against the source.
- ISOInternational Organization for Standardization
- UN ComtradeOfficial international trade statistics by HS code
- ITC Trade MapBilateral trade flows and tariff data
- FAOSTATFAO production and trade series for agricultural commodities
Price this with our desk
Grade, origin and window if you have them. If what you are carrying does not fit the sheet above, describe it in your own words and a trader will take it from there.