Bentonite Powder as an Iron Ore Pelletizing Binder — Function, Dosage, and Pellet Quality

Introduction

Before iron ore concentrate can be charged into a blast furnace or direct-reduction plant, fine ore is agglomerated into uniform, strong pellets. The binder that holds those green pellets together — through balling, drying, and firing — is almost always bentonite. This guide explains why bentonite powder is the standard pelletizing binder, how it works, typical dosage, and its effect on pellet quality.

Why Pelletizing Needs a Binder

Iron ore is ground to a fine concentrate to liberate the iron minerals, but fine powder cannot be fed directly to reduction furnaces. In pelletizing, moist concentrate is rolled into "green" balls in a disc or drum pelletizer, then dried and fired into hard, porous pellets. During balling, drying, and the early stages of firing, the green and dried pellets must resist cracking and breaking — that mechanical integrity comes from the binder.

How Bentonite Binds Iron Ore Pellets

Bentonite works as a pelletizing binder through several mechanisms:

• Moisture control: the swelling clay absorbs and holds water, regulating the moisture film between ore particles that makes balling possible.
• Plasticity and cohesion: hydrated montmorillonite gives the green ball plasticity so it forms and grows uniformly.
• Green and dry strength: bentonite bridges ore particles, giving green pellets the drop strength to survive handling and dried pellets the compressive strength to survive the induration furnace without disintegrating into fines.

Radhe Enterprise supplies high-swelling sodium bentonite powder with the viscosity and gel strength that make an effective pellet binder; the same properties are available in red ball granules for plants that re-mill to their own spec.

Typical Dosage

Bentonite is added at a low percentage of the ore concentrate — commonly in the region of 0.5–0.7% by weight, though the exact figure is optimised for each ore, its fineness, moisture, and the target pellet grade. Because bentonite adds silica and alumina (which slightly dilute the iron content of the finished pellet), plants aim to use the — which is why a high-quality, high-swell bentonite that performs at low dosage is economically valuable.