Bentonite Powder in the Paper Industry — Retention, Drainage, Pitch Control, and De-inking

Introduction

Modern paper machines run at high speed with closed water systems, and both realities depend on chemistry that controls how fibres, fillers, and contaminants behave in the wet end. Bentonite powder — used in "microparticle" retention programmes and as a pitch and stickies scavenger — is one of the quiet workhorses of the paper mill. This guide explains where bentonite fits in papermaking and why it improves both machine efficiency and sheet quality.

The Wet End Problem Bentonite Solves

At the wet end of a paper machine, a dilute slurry of fibre, mineral filler, and additives is drained on a moving wire to form the sheet. Two things must happen at once: fine particles must be *retained* in the sheet rather than washed through the wire, and water must *drain* fast so the machine can run quickly. Bentonite microparticle systems improve both simultaneously.

How Microparticle Retention Works

A bentonite retention programme is a two-component system:

1. A high-molecular-weight cationic polymer (or cationic starch) is added first. It adsorbs onto fibres and fines and flocculates them into large flocs. 2. Anionic bentonite microparticles are added after a shear point (the pumps and screens). The bentonite re-flocculates the sheared micro-flocs into a dense, uniform network.

The result is a "reversible" flocculation that survives shear: strong retention and fast drainage without the large, uneven flocs that hurt sheet formation. This lets mills increase machine speed, raise filler loading (reducing fibre cost), and cut fresh-water use.

Radhe Enterprise bentonite powder is finely milled with high surface area — the profile that makes an effective anionic microparticle.

Pitch and Stickies Control

"Pitch" (natural wood resins) and "stickies" (adhesive contaminants from recycled fibre) are the enemies of a clean, break-free paper machine. They deposit on wires, felts, and rolls, causing sheet defects, holes, and costly downtime. Bentonite's large, charged surface adsorbs these tacky, hydrophobic substances, detackifying them and carrying them out with the sheet or the reject stream instead of letting them agglomerate on equipment. For recycled-fibre mills in particular, bentonite is a standard tool in the stickies-control toolbox.