Characterisation of organic and inorganic components in productwater from a novel lignite drying process

摘要

Due to its high moisture content (up to 70%), lignite from the Latrobe Valley, Victoria, Australiamust be partially dried prior to combustion. The non-evaporative Mechanical ThermalExpression (MTE) technique has been investigated and shown to be a promising method forfuture application. During the MTE process, a product water stream, containing both organic andinorganic impurities released from the coal, is produced and has potential environmental impact.Knowledge of the nature of this product water will help determine the extent of water qualityissues related to the process and assist in the selection of appropriate treatment procedures and/orbeneficial reuse applications.This paper focuses on the characterisation of organic and inorganic components in MTE productwater as a function of processing conditions. Some South Australian lignites, which possesshigher intrinsic concentrations of inorganic components, were studied for comparison. Gaschromatography - mass spectroscopy (GC-MS) was used to identify major organic components.Selected elements, including calcium, sodium and magnesium, were quantified using inductivelycoupled plasma atomic emission spectrometry (ICP-AES).It was observed that the amount of organic carbon released to the product water increasedsubstantially with processing temperature and pressure for all samples. Processing conditions didnot so strongly influence the amount of inorganic constituents released to the product waterstream, but rather this was strongly influenced by lignite type.