Explosions of coal dust are a major safety concern within the coal mining industry. The explosion and
subsequent fires caused by coal dust can result in significant property damage, loss of life in underground
coal mines and damage to coal processing facilities. The United States Bureau of Mines conducted
research on coal dust explosions until 1996 when it was dissolved. In the following years, the American
Society for Testing and Materials (ASTM) developed a test standard, ASTM E1226, to provide a standard
test method characterizing the “explosibility” of particulate solids of combustible materials suspended
in air. The research presented herein investigates the explosive characteristic of Pulverized Pittsburgh
Coal dust using the ASTM E1226-12 test standard. The explosibility characteristics include: maximum
explosion pressure, (Pmax); maximum rate of pressure rise, (dP/dt)max; and explosibility index, (Kst). Nine
Pulverized Pittsburgh Coal dust concentrations, ranging from 30 to 1,500 g/m3, were tested in a 20-Liter
Siwek Sphere. The newly recorded dust explosibility characteristics are then compared to explosibility
characteristics published by the Bureau of Mines in their 20 liter vessel and procedure predating ASTM
E1126-12. The information presented in this paper will allow for structures and devices to be built to
protect people from the effects of coal dust explosions.
The evaluation of threats connected with the presence of methane in coal seams is based on our
knowledge of the total content of this gas in coal. The most important parameter determining the potential
of coal seams to accumulate methane is the sorption capacity of coal a. It is heavily influenced by the
degree of coalification of the coal substance, determined by the vitrinite reflectance R0 or the content of
volatile matter V daf. The relationship between the degree of coalification and the sorption capacity in the
area of the Upper Silesian Coal Basin (USCB) has not been thoroughly investigated, which is due to the
zonation of methane accumulation in this area and the considerable changeability of methane content in
various localities of the Basin. Understanding this relationship call for in-depth investigation, especially
since it depends on the analyzed reflectance range. The present work attempts to explain the reasons for
which the sorption capacity changes along with the degree of coalification in the area of Jastrzębie (the
Zofiówka Monocline). The relationship between parameters R0 and V daf was investigated. The authors
also analyzed changes of the maceral composition, real density and the micropore volume. Furthermore,
coalification-dependent changes in the sorption capacity of the investigated coal seams were identified.
The conducted analyses have indicated a significant role of petrographic factors in relation to the accumulation
properties of the seams located in the investigated area of USCB.
The coal exploitation in the Upper Silesia region (along the Vistula River) triggers the strata seismic
activity, characterized by very high energy, which can create mining damage of the surface objects, without
any noticeable damages in the underground mining structures. It is assumed that the appearance of the
high energy seismic events is the result of faults’ activation in the vicinity of the mining excavation. This
paper presents the analysis of a case study of one coal mine, where during exploitation of the longwall
panel no. 729, the high energy seismic events occurred in the faulty neighborhood. The authors had analyzed
the cause of the presented seismic events, described the methods of energy decreasing and applied
methods of prevention in the selected mining region. The analysis concluded that the cause of the high
energy seismic events, during the exploitation of the longwall panel no. 729 was the rapid displacements
on the fault surface. The fault’s movements arose in the overburden, about 250 m above the excavated
longwall panel, and they were strictly connected to the cracking of the thick sandstone layer.
Geodesic measurements of mining area deformations indicate that their description fails to be regular,
as opposed to what the predictions based on the relationships of the geometric-integral theory suggest.
The Knothe theory, most commonly applied in that case, considers such parameters as the exploitation
coefficient a and the angle of the main influences range tgβ, describing the geomechanical properties of the
medium, as well as the mining conditions. The study shows that the values of the parameters a = 0.8 and
tgβ = 2.0, most commonly adopted for the prediction of surface deformation, are not entirely adequate in
describing each and every mining situation in the analysed rock mass. Therefore, the paper aims to propose
methodology for determining the value of exploitation coefficient a, which allows to predict the values
of surface subsidence caused by underground coal mining with roof caving, depending on geological and
mining conditions. The characteristics of the analysed areas show that the following factors affect surface
subsidence: thickness of overburden, type of overburden strata, type of Carboniferous strata, rock mass
disturbance and depth of exploitation. These factors may allow to determine the exploitation coefficient a,
used in the Knothe theory for surface deformation prediction.
One of the main purpose of accurate blasting in open pit mining is to achieve optimum rock fragmentation.
The degree of rock fragmentation plays a significant role in order to control and minimise the
overall production cost including loading, hauling and crushing. In the present paper, the application of
a Number-Size (N-S) fractal model is intended to classify the blast fragmentation size in the Jalal-Abad
iron mine, SW Iran, using GoldSize image analysis software for four blasting with the obtained result
being compared with Kuz-Ram curves. To do this, the fractal dimensions via N-S log-log plots were
generated based on the output of the GoldSize software. The results indicated that the fragmented rocks
have a multifractal nature with four/five different fragmented populations in terms of size namely; the fine
rocks with the size of less than 16 cm, Mean-fragment values between 16 and 45 cm, In-range between
45 and 70 cm and finally, oversize larger than 70 cm.