What is the process of making bentonite granules

Bentonite granules are a versatile and valuable agricultural product widely used in soil improvement, water retention, and as a carrier for various fertilizers and pesticides. This article explores the intricate process of making bentonite granules, from the extraction of raw bentonite clay to the final product ready for use in agriculture.

Raw Material Extraction

The first step in the production of bentonite granules is the extraction of raw bentonite clay. Bentonite is a naturally occurring clay mineral that is predominantly composed of the minerals montmorillonite, beidellite, and nontronite. It is often found in deposits beneath the Earth’s surface, typically in sedimentary layers. Once these deposits are located, the mining process begins, and the bentonite-rich layers are excavated.

Crushing and Grinding

After extraction, the raw bentonite clay is transported to a processing facility, where it undergoes a series of crushing and grinding steps. These processes serve to break down the clay into smaller particles and remove any impurities or non-bentonite minerals. The resulting fine powder is easier to work with and is a crucial intermediate stage in granule production.

Mixing and Blending

The next phase involves mixing the powdered bentonite with other essential additives and binders. These additives can vary depending on the intended use of the bentonite granules. Common additives include organic materials, such as lignosulfonates, and inorganic binders like sodium silicate. This blending process ensures that the bentonite granules will have the desired characteristics, such as strength, stability, and water-absorbing capacity.

Granulation Process

The heart of the process is the granulation phase. This is where the powdered bentonite mixture is transformed into small, uniformly-sized granules. Several methods can be used for granulation, including:

  1. Roller Compaction: In this method, the powdered mixture is passed through a series of rollers that press and compact it into granules of the desired size. The pressure and gap between rollers can be adjusted to achieve the desired granule diameter.
  2. Agglomeration: Agglomeration involves creating granules through the use of a liquid binder or by agitating the mixture to promote adhesion. This method is particularly useful when the desired granules are smaller and require a high degree of uniformity.
  3. Extrusion: Extrusion involves forcing the mixture through a die, resulting in cylindrical or pellet-shaped granules. This method is popular for the production of granules with specific shapes and sizes.


Once the granules are formed, they contain moisture from the binding agents used in the previous step. To remove this excess moisture and increase the granules’ stability and shelf life, they are sent through a drying process. This typically involves using rotary dryers, fluidized bed dryers, or other drying machine.

Sizing and Screening

After drying, the bentonite granules go through a sizing and screening process. This step ensures that only granules of the desired size range are packaged for sale. Oversized or undersized granules are typically recycled back into the granulation process.

Quality Control

Throughout the entire production process, quality control is paramount. Various tests and inspections are conducted to ensure that the bentonite granules meet the specified standards for moisture content, granule size, binding strength, and other relevant properties. Any substandard batches are identified and rectified.

Packaging and Distribution

The final step in the process is packaging the bentonite granules for distribution. These granules are packaged in bags or containers suitable for easy handling and application in agricultural settings. Bentonite granules are distributed to agricultural suppliers, farmers, and other end users, where they can be used to improve soil quality, enhance water retention, and serve as carriers for various agricultural inputs.

In conclusion, the production of bentonite granules involves a series of carefully orchestrated steps, from the extraction of raw bentonite clay to the final packaging of the product. This versatile agricultural resource plays a crucial role in modern farming practices, contributing to improved crop yields and sustainable agricultural practices.

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