Boiler ash utilization in the Canadian pulp and paper industry

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Pulp and paper mill biomass boilers produce significant ash quantities in Canada, with British Columbia and Quebec being major contributors.
• Current ash management primarily involves landfilling, posing environmental and economic challenges, especially with increasing reliance on green fuels.
• There is a critical need for sustainable and beneficial uses of pulp and paper boiler ash to mitigate management difficulties.

Purpose of the Study:

• To review proposed and implemented beneficial uses of coal and hog (wood) ash globally.
• To provide a foundational step in identifying suitable applications for pulp and paper boiler ash based on ash properties and local opportunities.
• To support environmental and economic sustainability within the pulp and paper industry.

Main Methods:

• Literature review of global ash utilization practices.
• Analysis of ash properties and their suitability for various applications.
• Consideration of local opportunities and constraints for ash reuse.

Main Results:

• Identified large-scale applications: land application (nutrients, liming), construction materials (cement replacement, fill), mine site reclamation, and forest road stabilization.
• Highlighted smaller-scale applications: compost component, pH adjustment, blasting abrasive, and source of quartz for glass manufacturing.
• Emphasized the variability of ash chemical composition (fly and bottom ash) based on fuel source and combustion technology, necessitating careful consideration for specific applications.

Conclusions:

• Beneficial ash utilization offers a sustainable alternative to landfilling for pulp and paper mills.
• A comprehensive understanding of ash properties and local context is crucial for successful application screening.
• Further research and development can unlock the full potential of biomass boiler ash, promoting a circular economy in the industry.