Characterization of the mass distribution of Slovak brown coal after size reduction processes

Abstract

Distribution of pulverised particles is in general affected by the fragmentation process, initial size distribution, energy input, number of fracturing events, etc. and have been studied for several decades. Empirical studies of crushing and grinding by the mineral processing industry provide a major source of information on the distributions. There are many statistical relations describing the distributions of particles: between the number of particles and their size, or the particle mass and size.The aim of this paper is to reveal the fractal relation in the mass distribution of coal samples from locality Cíge¾ after size reduction processes-crushing and grinding. The acquired data can be obtained from sieve analyse, where the particles are distributed to various fractions. The fractal distribution is characterized by the fractal dimension D, that can be determined from the gradient of the graph of ln M against ln r, where M denotes the cumulative mass of all particles with the size less then r. It is useful to specify the range over which the fractal relation is a good fit to the experimental data. The range is bounded by the upper and lower limit on the particle size. From the obtained values it can be concluded that the value of fractal dimension for the ground sample is higher, due to higher number of reducing events.

Keywords

• distribution
• fractal dimension
• coal
• crushing
• grinding