A Characterisation of the Ash Content of Conifer Stump Wood Hogfuel

Abstract

A study was carried out in the southeast of Ireland in which stumps were harvested on two conifer clearfell sites: a peat soil site and a peaty gley site. The stumps were harvested by excavator machines with a stump harvesting head which split and shook the stumps during excavation in order to remove soil. The stumps were stored on the site for a period of 9 to 10 months to further reduce soil contamination by weathering. The stumps were forwarded to the roadside and comminuted into hog fuel with a shredder. Samples were collected and prepared in three ways: clean stump wood, hog fuel as received, and sieved hog fuel. The clean stump wood was collected from stumps with a chainsaw prior to shredding. The hog fuel as received was collected from the shredder. The sieved hog fuel was prepared using an oscillating screen sieve with sieves ranging between 1 mm and 63 mm circular holes. The samples were analyzed for ash content using a muffle furnace, and gross calorific values using an oxygen bomb calorimeter. Results have allowed for the comparison of clean stump wood and hog fuel as received, which identifies the proportion of ash content associated with soil contamination, and that which is inherent to stump wood. Results also describe the ash content and calorific value along with the particle size distribution and describe which particles, and thus the proportion of the fuel, need to be sieved out in order to increase the fuel quality to an acceptable condition.