Effects of Binder Type on Pellet Breakdown and Dust Production

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Objective(s): Determine effect of the ore concentrate characteristics (surface chemistry and size distribution), binder dosage and type of bentonite on the pellet quality and on the dustiness of the pellets.

Justification: Dustiness and breakdown of pellets is a concern for all of the plants, and it has been assumed that bentonite quality and dosage affects pellet dustiness. However, this has never been confirmed, due to the lack of a method for directly measuring the dustiness of pellets. The industry is particularly interested in determining whether it is necessary to continue to use High-PWA bentonites, which are becoming more expensive. It is therefore important to the industry to determine whether use of the lower-cost Low-PWA bentonites will allow production of pellets without introducing dust problems. It is also important to determine the extent to which the surface chemistries of bentonite and of iron ore affect the pellet quality.

Description of Proposed Work: Pellets will be produced using the fluxed concentrate from an operating Minnesota plant, using bentonites of different grades and added at varying dosages. The surface chemistries of the bentonites and of the ore concentrate will be determined using streamingpotential measurements, so that the interactions between bentonite and ore particles can be determined. The PWA values will be determined with both distilled water, and with water that has the same composition as filter cake moisture. A custom-built dust tower at MTU, which is the only available facility for measuring pellet dustiness, will be used to evaluate the changes in dust production from fired pellets as the bentonite type and dosage are varied. This will be used to measure (a) Total dust; (b) Particles finer than 10 micrometers (PM10) and 2.5 micrometers (PM2.5); and (c) Particles finer than 1 micrometer (PM1.0). Degradation of the pellets as they fall through the dust tower will also be measured.

GRADUATE STUDENT: Joseph Halt