BRIQUETTING PEAT AND PEAT COAL MIXTURES

This work shows that dried peat from the Ohinewai deposits of the Waikato River Valley region of New Zealand can be successfully briquetted without using a binder. It also evaluates this peat as a binder for the briquetting of surplus sub-bituminous coal fines from the nearby Waikato coalfield. Initially a laboratory scale press and die were used to produce briquettes of peat and various peat/coal mixtures. The physical properties and water resistance of the briquettes were analysed in relation to the varying briquetting parameters including moisture content, coal fraction and temperature. Extremely high quality briquettes were produced from pure peat and peat-coal mixtures containing up to about 50% coal, after which strength properties became marginal. The laboratory findings were applied to pilot extrusion trials by using a woodwaste briquetting press. Excellent "firelogs" were produced in several short runs, but owing to a lack of dried peat no attempt was made to optimise briquetting conditions for this machine. Insufficient "firelogs" were produced to carry out meaningful combustion tests. The immediate success achieved in these limited trials suggests that this method of agglomerating peat should not pose too many technical difficulties if taken to commercial production and that the prospect of using peat as a briquetting binder deserves due consideration. © 1990.