Rudarski radovi br 4 2011 - Institut za rudarstvo i metalurgiju Bor

Now, these mines are production<br />
facilities with low production [1], [12].<br />
The aim of realized research within this<br />
topic is to give a new approach to pillar<br />
mining methods, and within the research<br />
framework are mines with underground<br />
mining of coal in Serbia. In addition to the<br />
method of analysis and synthesis, the<br />
experimental methods and mathematical<br />
modeling methods were used in<br />
studies[13],[20].<br />
2. THE USE OF COAL PILLAR<br />
MINING METHODS FOR SEAMS<br />
WITH LARGER THICKNESS<br />
Pillar mining methods with the blasting<br />
technology, applied in the underground<br />
coal mines in Serbia, are characterized<br />
by the following:<br />
- Wide use due to a possibility of<br />
adjusting the geometry of working<br />
front and exploitation tactics to the<br />
complex mining conditions,<br />
- low production and productivity with<br />
a need to operate a number of<br />
excavation units and deconcentration<br />
of mining operations,<br />
- high consumption of raw materials in<br />
the preparation and excavation<br />
process,<br />
- high share of preparatory works.<br />
Pillar mining methods are applied for<br />
mining of coal seams in complex naturalgeological<br />
conditions, that is in the parts<br />
of deposit in which the rational application<br />
of longwall face method is short<br />
mechanized slopes is not used [21], [27].<br />
The method is used with a technology<br />
short-drill blasting for thickness of seams<br />
2 - 6m, and by use the deep-drill blasting<br />
(DDB) and to a thickness of 10 m.<br />
The basic principle of pillar mining<br />
method consists of excavation the prepared<br />
pillars by pulling the excavation<br />
slopes on both sides. Basic preparation for<br />
implementation of this mining method<br />
consists in making room per direction of<br />
coal seam - the basis for excavation where<br />
the excavation field is shared by drop of<br />
seam on the sloping pillars approximately<br />
30 m in length.<br />
Bases for excavation are made in the<br />
floor area of coal seam floor area (in the<br />
case flooding floor, a protective plate,<br />
thickness from 0.5 to 1.0 m, is left) and<br />
during excavation they are mutually connected<br />
with connecting links for better<br />
organization of transport and ventilation.<br />
Preparation of excavation bases is carried<br />
out by drilling-blasting works and it is<br />
usually supported using the circular steel<br />
support.<br />
Coal is produced in three phases, as<br />
follows:<br />
- Phase I of excavation – preparation<br />
for excavation (exploitation sites)<br />
- Phase II of mining – coal obtaining<br />
from the side wings in the<br />
overlying and underlying part and<br />
over the excavation preparation<br />
- Phase III of excavation – coal<br />
obtaining from the side wings in<br />
the underlying part over the<br />
junction excavation base and<br />
excavation preparation.<br />
Excavation preparation is made from<br />
the excavation per underlying stratum coal<br />
seam to the length of 30m and the drilling<br />
– blasting works are carried out<br />
Upon completion of excavation preparation<br />
begins, the excavation of the side wings<br />
and over stope part starts. Width of side<br />
wings towards the old work is 3.0 m, and to<br />
the next pillar 2.0 m. Obtaining of coal at<br />
No 4, 2011. 74<br />
MINING ENGINEERING