Grant: Engage Plus Grants Program

Domtar Corporation owns and operates four pulp mills in Canada. Lignin is a by-product of the pulping process that can provide energy for the mills, but also has many potential applications in the energy, materials and chemical industries as adhesives, agricultural chemicals, adsorbents, coatings, dispersants, fuel additives, binders and resins. These applications have not yet been fully realized partly due to challenges in handling the lignin: the lignin that is produced is an extremely fine powder that is very dusty, cohesive, thermally sensitive, and exhibits extremely poor flowability. It is therefore difficult to store and is not easy to feed uniformly and continuously into equipment required to process for many of its possible applications.Granulation is the process that agglomerates fine powder particles into larger agglomerates called granules. Granulation reduces the powder dustiness and tendency for caking, increases the bulk density, and improves flow properties. Research from the Engage Grant confirmed that lignin can be wet granulated in a high shear granulator. The granules produced were almost spherical, hard and resistant to attrition, and the size can be varied by changing the process parameters. The granules are easy to handle thereby overcoming some difficulties that are currently preventing lignin from realizing its full range and extent of potential applications. The goals of the NSERC Engage Plus Grant project will be to: (a) measure the hygroscopicity of lignin, (b) investigate wet granulation of lignin using a drum granulator, and (c) comparison of lignin granules and lignin pellets. The hygroscopicity affects the interaction of the lignin with the liquid binder during wet granulation, drum granulation can potentially granulate the large volumes of lignin that Domtar produces, and a comparison of granules versus pellets will provide critical information to determine the optimal lignin processing method. For the drum granulation trials, The effect of drum fill level, rotation rate, binder concentration and total binder solution volume will be examined. Granule and pellet properties that will be measured include size, shape, density, hardness, resistance to cohesion and consolidation, and ability to flow.