Partitioning behaviour of some toxic trace elements during coal combustion- the influence of events occurring during the deposition stage

The distribution of trace elements in a sub-bituminous coal seam and a peat dome both located in the Waikato/Hauraki region of the central North Islan d of New Zealand is controlled by the presence or absence of inorganic laye rs. One of these is a volcanic ash fall layer (tephra) containing high tita nium and low calcium levels compared to inorganic phases in other regions o f the seam. When coal samples taken from the centre of the seam and includi ng the tephra derived parting were combusted in an underfeed stoker, the pa rtitioning behaviour of the toxic class II volatile boron was found to be s ignificantly different than for samples of coal from other parts of the sea m not including the tephra derived parting. Reasons for the different behav iour are identified. (C) 2000 Elsevier Science Ltd. All rights reserved.