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

obtained from one excavated base in the<br />
excavation field, which is done by simultaneous<br />
operation of three sites. Such formed<br />
excavation sites make one pillar stope.<br />
Capacity of excavation the pillar stope<br />
with the technology of obtaining the DDB<br />
consists of the sum capacity of stope in progress<br />
(Phase I) and stope in drawing (with<br />
over stope obtaining - Phase II and III).<br />
Qv=qvn + qvp<br />
where:<br />
qvn - stope capacity in progress,<br />
qvp – stope capacity in drawing.<br />
Stope capacity in progress is:<br />
qvn = Fn x γ x n1<br />
where:<br />
Fn = 8.52 m 2 – stope profile in progress<br />
γ = 1.30 – bulk density of coal<br />
n1 = stope progress in a shift (m/shift)<br />
Values Fn and γ are constant, until<br />
value n1 is variable and mainly depends on<br />
work organization and used mechanization.<br />
Stope capacity in drawing is calculated<br />
by the expression:<br />
qvp = Fp x γ x ζ x n2, (t/shift)<br />
where:<br />
Fp – stope cross section in drawing (m 2 )<br />
γ – bulk density of coal (1.30)<br />
ζ – utilization coefficient<br />
n2 – rate of stope drawing (m/shift)<br />
Fp = (S x d) - Fn<br />
Cross section area is determined by<br />
slope width S (8.5 m 2 ), coal seam thickness<br />
d less the stope profile in progress<br />
(8.5 m 2 )<br />
Fp = 8.5 d – 8.5<br />
Utilization coefficient is adopted as a<br />
value γ = 0.70 %, obtained based on statistical<br />
analysis of experienced data.<br />
Total available working time per shift<br />
is different from mine to mine, and for the<br />
needs of calculation the duration time of<br />
individual work operations, the following<br />
average values were adopted:<br />
- working time in a pit.............. 450 min<br />
- coming to a site ...................... 30 min<br />
- break during shift ................... 30 min<br />
- departure from site ................. 30 min<br />
- effective working time per shift... 360 min<br />
Time of coal production cycle depends<br />
on time of some working operations:<br />
T = t1 + t2 + t3 + t4 + t5 + t6, (min)<br />
where:<br />
t1 – time of preparation works (min)<br />
t2 – time for making the blast holes<br />
(min)<br />
t3 – time for charging and ignition the<br />
blast holes (min)<br />
t4 – time for loading and transport of<br />
coal<br />
t5 – time for support or stope ensuring<br />
(min)<br />
t6 – time for realization the ancillary<br />
working operations (min)<br />
Times t1, t5 and t6 for all seam thicknesses<br />
have the same values, until the<br />
times t2, t3 and t4 are directly dependent on<br />
a seam thickness that is excavated.<br />
Based on time analysis of working operations<br />
(t2, t3 and t4) and change of seam<br />
thickness (d= 3 – 10 m), a curve of progress<br />
rate change – stope drawing, was<br />
formed.<br />
b<br />
(m/shift),<br />
n2 = a + d<br />
where:<br />
a = 0,62 and b = 1.75, a coefficient obtained<br />
by analysis the time of realization<br />
of some working operations.<br />
No 4, 2011. 76<br />
MINING ENGINEERING