Boiler ash utilization in the Canadian pulp and paper industry

Pulp and paper mill biomass boilers generate large quantities of ash in Canada with British Columbia (BC) being the highest ash generating province followed closely by Quebec. Generally, the generated ash is landfilled, particularly in BC, with only a small amount being used beneficially. It is anticipated that the difficulty asso-ciated with the management of ash will worsen over time as the industry increases its reliance on green fuel. Thus, there is a strong need to identify beneficial uses of pulp and paper boiler ash for the sake of environmental and economic sustainability. The purpose of this report is to provide the first step in this direction, a review of proposed or implemented uses for coal and hog (or wood) ash around the world. Considering both the properties of the ash and local opportunities, this could be the first step toward screening the applications that may apply to individual mills. Several large-scale practices use ash, such as land application (as a nutrient source or as a liming agent), use in the construction industry (as a replacement for cement or as a fill material), and reclamation of mine sites and stabilization of unpaved forest roads. In some cases, relatively small-scale applications have been used which included uses such as a compost component, agent for pH adjustment of liquid streams and slurries, blasting abrasive, and source of quartz for glass manufacturing to name a few. It is important to note that the chemical nature of both fly and bottom ashes can be quite variable due to the type of wood residues combusted as well as combustion equipment used and must be considered in identifying beneficial applications.

Automated summary

The pulp and paper mill biomass boilers in Canada generate large quantities of ash, with most being landfilled and only a small amount being used beneficially. The challenges associated with ash management are expected to worsen over time, highlighting the need to identify beneficial uses for environmental and economic sustainability. Various large-scale and small-scale applications for ash have been identified globally, underscoring the importance of considering the chemical nature of the ashes for specific beneficial applications.