An innovative approach to replace bentonite in hematite ore pelletizing with organic binder

ABSTRACTABSTRACTThere is a continuous endeavor to replace bentonite with any other suitable inorganic or organic binders. Organic binders generally burn at around 300–350°C and lose their binding property and cause crumbling in most cases. This study aimed to develop a process to use a suitable organic binder for the development of blast furnace quality pellets using some additives which can overcome the strength loss of pellets during induration. The wastes generated from pulp industries viz. Ca-lignosulphonate (Ca-LS) and Na-lignosulphonate (Na-LS) have been used as binders in hematite ore pellets. To alleviate the strength loss at 300–350°C, lower iron oxide (FeO and Fe3O4) containing materials viz. Linz-Donawitz (LD) sludge and mill scale have been added. FeO and Fe3O4 in these materials will be oxidized at the mild oxidizing atmosphere of the induration strand and initiate diffusion bonding at around 300°C. Therefore, the strength loss due to burning will be compensated by the strength gain due to diffusion bonding. From the experimental study, it has been found that Ca-LS is a better binder than Na-LS and LD-sludge (LDS) is a better additive than mill scale. A combination of 0.4% Ca-LS with 5% LDS addition can prevent strength deterioration at 300–350°C during drying and gives a good-quality pellet in terms of strength, thermal shock resistance, reducibility, reduction degradation, and swelling index, which is comparable with bentonite added pellet. Thus, 04% Ca-LS with 5% LDS shows its good application potential to replace bentonite in hematite ore pelletizing.KEYWORDS: Ca-lignosulphonateNa-lignosulphonateLD sludgemill scalebentonite replacement AcknowledgmentAuthors thankfully acknowledge the financial assistance offered by M/s Tata Steel, Jamshedpur to carry out this investigation and they wish to express their sincere gratitude to the Director, CSIR-NML for his kind permission to publish this work.Disclosure statementNo potential conflict of interest was reported by the author(s).