New concept for the calculation of the trace element affinity in coal

The present models for the calculation of the trace element affinity between organic and inorganic parts of coal are critically evaluated and a new concept of calculation is proposed. This new concept of calculation is based on the experimental data characterising coal fractions separated from coal samples using sink-float technique. It consists in the calculation of (a) organic element association (OEA) supposing constant concentration of the element in organic phase and (b) maximal organic element association (OEAmax) supposing maximal possible concentration of the element in the organic phase of all coal fractions. For one coal sample OEA and OEAmax are calculated. It must be valid that OEA≤OEAmax. This relation is not true for some elements e.g. Ge and Ga, which usually have extremely high concentration in the lightest coal fraction. Contemporary with OEA the inorganic element association (IEA) is evaluated. Using least squares method the IEA can be recalculated among mineral groups present in coal. The model was successfully tested on one sample of bituminous coal and one sample of brown coal.