Characterization of ashes produced from different biomass fuels used in combustion systems in a pulp and paper industry towards its recycling

abstract

In the boilers of pulp mills the fuel blends used vary because they are essentially composed of residual forest biomass. Consequently, the physical-chemical properties of the produced ash streams can exhibit high temporal variability, making their proper management and recycling difficult. This study aims to characterize the ash from the incineration of biomass samples used as fuel in order to understand its influence on the properties of the generated ash fluxes. This can anticipate suitable blending procedures that minimize the variability of the ash characteristics. For this purpose, typical biomass samples (eucalyptus bark, treetops and knots, pine treetops, silver wattle, Sydney golden wattle, white poplar, and grey willow) were incinerated (at 550 and 825 degrees C) and the resulting ashes were characterized. The thermal behavior of the biomass was evaluated by TG/DTA and the generated ash content was determined. The particle size distribution (laser diffraction), morphology (SEM), mineralogy (XRD), and chemical composition (XRF) were other evaluated properties. From the results obtained it is concluded that the ashes cannot be used as raw materials for clinker production. However, they can be used in concrete and mortar formulations, as a cement substitute or as filler. The maximum incorporation amount de-pends on the type of biomass used, ranging from 54 wt% for pine treetops to 100 wt% for eucalyptus bark. This knowledge is fundamental to understand how to optimize the biomass blends used in industrial combustion systems to obtain ashes with suitable properties to be used as secondary raw materials in building materials formulations.

keywords

THERMOGRAVIMETRIC ANALYSIS; CHEMICAL-COMPOSITION; FLY-ASH; COCOMBUSTION; COAL

subject category

Agriculture; Biotechnology & Applied Microbiology; Energy & Fuels

authors

Capela, MN; Tobaldi, DM; Seabra, MP; Tarelho, LAC; Labrincha, JA

Groups

G4 - Renewable Materials and Circular Economy

Projects

InPaCTus - Innovative Products and Technologies from Eucalyptus Project (InPacTus)

Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

acknowledgements

This work was supported by Portugal 2020 through European Regional Development Fund (ERDF) in the frame of Operational Competitiveness and Internationalization Program (POCI) in the scope of the project INPACTUS, POCI/01/0247/FEDER/21874, project CICECO - Aveiro Institute of Materials, UIDB/50011/2020, UIDP/ 50011/2020 & LA/P/0006/2020 cofinanced by national funds through the FCT/MEC (PIDDAC). It is acknowledge the financial support to CESAM - Centre for Environmental and Marine Studies by the Portuguese Foundation for Science and Technology (FCT)/Ministry of Science, Technology and Higher Education (MCTES) (UIDP/50017/ 2020+UIDB/50017/2020+LA/P/0094/2020), through national funds.