Natural Fragmentation Model of Zirab Coals, Iran

Abstract

Iran's coals occur in the Alborz range (north) and Central Iran basins. The Zirab is typical coalfield in the Alborz coal basin. From litho types of view, the coals are mainly clarovitrinite to clarodurite type which are used as source of coking coal for metallurgical factories. During the research we used 10 typical samples from Zirab coal mine to estimate fragmentation model of natural particle-size distribution of these coals. Prediction of natural fragmentation properties from coals was the main aim of this research. In order to calculate the natural fragmentation model at any stage of the extraction (or sizing) operation, we tried to find similar models that combine both natural fragmentation and degradation through natural crushing. The results our research suggest a power-law and a log-normal behavior for the distribution of the smaller and larger coal fragments, respectively. We show that the probability function that models the production of particles of different size from an initial mass and sorts that distribution is related to mass and compositional factors of coal particles. Also, our studies showed that during the fall of coals from 4m height, fragmentation followed a range of 10 percent, per time for particles smaller than 5 mm diameter. It means that if the processes would repeat 10 times, 100 percent of coals would crush to the size of less than 5 mm.

Interpreting two-dimensional cuts through broken geologic objects: Fractal and non-fractal size distributions

“…Hartmann (1969) suggested that the discrepancy between lognormal and power-law fi ts is in part due to limitations of observational methods , which must always undercount the smallest particles. Some studies have shown that fragmentation processes can produce fragments that are best described as either mixed lognormal-power law or two-power-law populations (e.g., Meibom and Balslev, 1996;Tavassoli and Shirvani, 2000;Yazdi and Esmaeilnia, 2009). …”