a quarter of an hour bringing the temperature of the mixture to 90 u00b0 c the final humidity was then 8 the mixture was then subjected to an agglomeration treatment by pressure compacting under the same conditions as in example 1 in this way coal dust nuts are obtained having sufficient cohesion when fresh to be able to undergo transportion the latter are then subjected to stoving for a period of two hours at a temperature of 220 u00b0 c the strength of these nuts measured as in example 1 shows the following values these nuts are then immersed in cold water no disagregation was observed even after several hours of immersion the mechanical strength of the nuts remained unchanged after their dwell in water and no degradation of their surface condition was observed during their handling after immersion this example shows that the addition of 5 of native starch and 0 05 of ammonium persulfate by dry weight with respect to the weight of fuel dust enables agglomerates to be obtained satisfying the requirements of the technique from the point of view of mechanical strength and behaviour to water to a mixture of coal dust and starch identical with that of example 2 and this under the same conditions 50 g of.