COMPREHENSIVE INVESTIGATION OF THE LIBERATION CHARACTERISTICS OF PYRITE AND OTHER ASH-FORMING MINERALS FROM COAL

The objective of this project is the development of methods for the measurement, prediction and modeling of the liberation characteristics of mineral matter and pyrite from coal, and to implement these findings in viable computer-simulation systems for coal cleaning plants. The central thrust of the project will be based on using the Andrews-Mika diagram as a convenient and experimentally verifiable model for the liberation characteristics of the constituents of coal during comminution. In order to establish the Andrews-Mika diagram, it is necessary to develop efficient techniques for density fractionation and for the measurement of the liberation spectrum in products obtained from the comminution of narrow composition fractions of coal. Dense-liquid techniques are used to produce fractionated samples, and image-analysis techniques, using linear-intercept analysis, are used to measure the liberation spectrum. The prediction of the liberation of mineral matter and pyrite from coal after comminution is based on a linear stochastic model for the description of the mineralogical texture and the random fracture pattern associated with the comminution process. Stereological correction of the distribution of linear grades is required for both the measurement and prediction of the true distribution of volumetric grades in the particle population