A continually fed pile of particulate solids experiences the occurrence of intermittent avalanches, which are issued to maintain the heap below some critical state. Previous work has indicated that the avalanching behaviour of powders may be related to their flowability, with the analyses being principally based on the power-law distribution of the larger events. Here, the strange attractors of the time series of avalanche weights have been analysed by using the correlation dimension. The correlation dimension, closely related to the fractal dimension, was found to characterise the flow of coals possessing good and poor handleability, as evidenced by their Durham cone indices. This approach revealed a, bandwidth limited, high level of deterministic chaos occurring within the avalanching of material of good flow. A significantly lower level of chaotic content was recorded in the poor handleability situation, along with avalanche suppression, of the midrange values, resulting in the measurement of some very large events. The correlation method yielded a single parameter for the strangeness of the attractors and provided a useful insight to the differing flow regimes within industrial coals.