Ash properties relevance to beneficial uses

Area of Science:

• Environmental Science
• Materials Science
• Waste Management

Background:

• Wood ash from Canadian pulp paper mills (PPM) is typically landfilled.
• Heterogeneity and variable quality limit beneficial ash applications.
• Limited data exists on PPM wood ash composition for diverse uses.

Purpose of the Study:

• To develop a comprehensive database of wood ash quality from PPM.
• To analyze physical, chemical, and engineering properties of different ash streams.
• To identify potential beneficial applications for wood ash.

Main Methods:

• Collected bottom ash (BA), multiclone ash, and electrostatic precipitator (ESP) ash samples from PPM.
• Analyzed ash samples for properties relevant to construction, compost, soil amendment, and waste stabilization.
• Compared ash quality across different mills and within individual ash streams.

Main Results:

• Significant variations in ash quality were observed between mills and ash streams (e.g., unburned carbon content).
• Multiclone ash exhibited higher unburned carbon than ESP ash.
• Ash properties varied widely, impacting suitability for specific applications.

Conclusions:

• The traditional definition of fly ash (FA) should be refined to distinguish between multiclone and ESP/baghouse ash.
• Ash segregation at the source is crucial to preserve quality for specific applications.
• This approach can divert wood ash from landfills, promote beneficial reuse, and reduce a mill's carbon footprint.