Organic Binders: The Future of Iron Ore Pelletization

This presentation explores the shift from conventional bentonite to advanced organic binders in iron ore pelletization. Organic binders deliver higher efficiency at lower dosage, improve pellet quality (GCS, CCS, and drop count), and eliminate silica/alumina dilution — enabling production of premium, high-grade pellets demanded by modern steelmaking. Backed by recent research and market trends, this work highlights how organic binders enhance process performance, improve reducibility, and align with the industry’s move toward sustainable and high-value agglomerates.

1. Next-Gen Pelletization: High-Strength Pellets with Organic Binders
Trinay Majumder
2025

Abstract
Organic binders (polysaccharides, cellulose derivatives, starches, synthetic polymers such as
polyacrylamide and functionalised copolymers) are rapidly gaining attention as alternatives or
supplements to bentonite in iron-ore pelletizing. Compared with bentonite, organic binders can
reduce impurity (SiO₂/Al₂O₃) dilution of pellets, lower required binder dosage, improve reducibility
and sintering behaviour, and permit production of higher-grade pellets for direct-reduction and
high-grade steelmaking. Experimental and review literature shows organic binders can match or
exceed green compressive strength (GCS), cold/dry compressive strength (CCS/DCS) and drop-count
performance when optimised, often at dosages an order of magnitude lower than bentonite. This
paper reviews binding mechanisms, summarizes how organics improve key pellet parameters (GCS,
CCS, drop count), contrasts them with bentonite, and places these technical trends alongside recent
market drivers pushing adoption of organic binder technology.

Keywords
Iron ore pelletizing; Organic binders; Bentonite; Pellet strength; Metallurgical performance; Green
pellet; Sustainability.

Introduction
Pelletization remains a cornerstone of modern iron-ore agglomeration for blast furnace and direct
reduction routes. Historically, bentonite (a natural swelling clay) has been the dominant binder due
to low cost and robust green strength. However, bentonite contains aluminosilicate impurities that
dilute pellet Fe content, negatively affect metallurgical performance (reducibility, slag chemistry)
and require higher fluxing during steelmaking.
In response, research and industrial practice are increasingly evaluating organic binders —
starches, carboxymethylcellulose (CMC), gelled starch, pectin and synthetic polymers (e.g.,
polyacrylamide derivatives) — which can deliver required pellet mechanical properties at much
lower dosage and with fewer chemical penalties to pellet grade. Recent reviews and experimental
studies highlight the mechanisms and performance of organic binders, and several market reports
indicate growing demand for higher-grade agglomerates that favour bentonite reduction or
substitution.

2. Why Organic Binders are Better Than Bentonite:

Parameter Bentonite Organic Binder
Impurity Addition Adds 0.8–1.6% SiO₂ and Al₂O₃ Negligible impurity addition
Iron Content
Reduction
~0.6–1.3% due to gangue
addition
No iron dilution
Combustion Residue Non-combustible Fully combustible (low ash residue)
Pellet Strength High dry and wet strength Comparable with optimization
Reducibility Moderate Improved due to higher Fe content
Environmental Impact Mining, dust, and disposal issues Biodegradable, renewable source
Cost Low Higher, but offset by performance
gains

Organic binders such as carboxymethyl cellulose (CMC), polyacrylamides, starch derivatives, and
lignosulfonates function by increasing capillary forces, promoting inter-particle bonding, and
enhancing pellet surface cohesion. Their full combustion during firing leads to higher iron content,
lower gangue, and better furnace efficiency.
Furthermore, organic binders are particularly effective in direct reduction (DR) grade pellet
production where low gangue levels are critical.

4. Effects on key pellet parameters: GCS, CCS and Drop Count:
Green Compressive Strength (GCS):
GCS measures the load green (unfired) pellets can withstand without cracking. Reports show
organics can produce competitive or higher GCS when properly formulated and dispersed. Typical
desirable GCS ranges for industrial pellets are ~30–90 kg/cm² (literature ranges vary by feed and
process). Organics achieve target GCS by creating strong adhesive films and good particle wetting
while avoiding excessive water hold-up that weakens pellets.
Cold/Dry Compressive Strength (CCS / DCS):
After drying or firing, pellet compressive strength must meet handling and transport requirements.
Organics that char to create a favourable pore network and sintering aid can produce CCS
comparable to bentonite systems — though success depends on induration profile and binder
selection. Some organics (gelled starch, certain cellulose derivatives) have shown higher softening
temperatures and good dry strength relative to bentonite.

3. Drop count / drop strength:
Drop count (or drop number) evaluates resistance to mechanical impact during handling. Studies
indicate bentonite tends to increase drop count (improve impact resistance) because the clay
provides plastic deformation energy absorption in green pellets. However, upgraded/activated
bentonites or optimised organic formulations can achieve similar or better drop counts. Work on
binder blends and activation shows the drop performance gap can be closed while preserving
higher pellet grade.

3. Conclusion
The use of organic binders in iron ore pelletization represents a shift toward cleaner, more efficient,
and sustainable steelmaking practices. While bentonite remains cost-effective, its limitations in
purity and metallurgical performance are prompting the adoption of organic alternatives. With
continued development and process optimization, organic binders can deliver significant
improvements in pellet quality, iron yield, and environmental performance.

4. References:
1. Arol, A.I., & Aydogan, Z. (2004). Alternative binders to bentonite for iron ore pelletizing.
Minerals Engineering, 17(3), 335–337.
2. Eisele, T.C., & Kawatra, S.K. (2003). A review of binders in iron ore pelletization. Minerals
and Metallurgical Processing, 20(1), 1–15.
3. Kappen, P., & Teague, M. (2016). Organic binders for iron ore pelletization. Ironmaking &
Steelmaking, 43(1), 13–23.
4. Tavares, S., Fonseca, D., & de Moraes, C.A. (2020). Development of organic binders for iron
ore pelletization. Journal of Materials Research and Technology, 9(6), 14567–14574.
5. Indian Bureau of Mines. (2022). Iron Ore Pelletization - Status & Trends. Technical Report.
6. Ma K., Strength variation of green pellets and ..., 2025 (pectin and other organics)
7. Reuters – Vale reduces forecast for pellet/agglomerates output (illustrates
market/operational sensitivity), 2025.