The effects of Drilling and Blasting Performance on Fragmentation in a Quarry and Time for Loading, Secondary Breaking and Crushing

Abstract

Small-scale mining operations are characterised by a large variety of equipment availability and
a high level of operational flexibility. Mine planning is usually scarce or absent in small quarries
in Brazil, and mine management generally focuses on daily operations. As a result, analysis of
the effects of unit operations, such as blasting, over the whole mining process is often neglected.
The goal of the following project was to study the effect of production blasting on loading and
hauling times, secondary breaking times and primary crushing times at the Experimental Mine of
the Research Center for Responsible Mining of the University of São Paulo, Brazil. The operations
analysed included blasts that performed:
•• under the average operational standard, defined in this paper as Case 1
•• according to quarry standards, defined in this paper as Case 2.
In order to establish the effects of blasting on the downstream process, three key performance
indictors were used:
1. The time taken to load the truck, when there is the need for material selection. Due to the
fact that we do not have an operational baseline, the increase in time cannot be established,
meaning that we must content ourselves with comparing the mean time in each scenario.
2. The average time used for secondary breaking machinery.
3. The time required for the primary crusher to fully process the load of a single truck. The
results obtained indicate correlations between the coarseness of the blasted material and these
operational times. Solutions are suggested and evaluated for the improvement of the smallscale
mining process.

Full text

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 

 
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 
 
 
 
 
 




constrains of cost?


self-defeating in terms of drilling accuracy and results in an
drilling is supervised in order to grant correct collar

   
  
   
   
 

 
 

 
  
 

 
 






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

   
  


   

  






















1st Quartile 248.00
Median 271.50
3rd Quartile 446.25
Maximum 941.00
301.94 385.44
258.14 282.95
134.23 194.40
A-Squared 6.22
P-Value <0.005
Mean 343.69
StDev 158.78
Variance 25210.74
Skewness 1.63526
Kurtosis 2.37171
N 58
Minimum 185.00
Anderson-Darling Normality Test
95% Confidence Interval for Mean
95% Confidence Interval for Median
95% Confidence Interval for StDev
8006004002000
40
30
20
10
0
seconds
Median
Mean
400375350325300275250
95% Confidence Intervals
tt case 1
1st Quartile 245.00
Median 268.00
3rd Quartile 311.50
Maximum 1182.00
266.46 345.16
258.80 288.10
119.83 176.64
A-Squared 7.56
P-Value <0.005
Mean 305.81
StDev 142.77
Variance 20382.31
Skewness 4.8299
Kurtosis 27.9528
N 53
Minimum 198.00
Anderson-Darling Normality Test
95% Confidence Interval for Mean
95% Confidence Interval for Median
95% Confidence Interval for StDev
12009607204802400
40
30
20
10
0
seconds
Median
Mean
350325300275250
95% Confidence Intervals
tt case 2




1st Quartile 195.00
Median 233.00
3rd Quartile 341.00
Maximum 1862.00
199.17 515.20
199.91 279.95
314.57 547.41
A-Squared 5.52
P-Value <0.005
Mean 357.19
StDev 399.44
Variance 159553.77
Skewness 3.2710
Kurtosis 10.2223
N 27
Minimum 148.00
Anderson-Darling Normality Test
95% Confidence Interval for Mean
95% Confidence Interval for Median
95% Confidence Interval for StDev
180015001200900600300
16
12
8
4
0
seconds
Median
Mean
500450400350300250200
95% Confidence Intervals
tc case 1
1st Quartile 276.50
Median 314.00
3rd Quartile 389.00
Maximum 734.00
316.23 359.83
290.00 356.86
80.36 111.65
A-Squared 1.44
P-Value <0.005
Mean 338.03
StDev 93.44
Variance 8731.14
Skewness 1.39141
Kurtosis 3.40287
N 73
Minimum 186.00
Anderson-Darling Normality Test
95% Confidence Interval for Mean
95% Confidence Interval for Median
95% Confidence Interval for StDev
7506004503001500
20
15
10
5
0
seconds
Median
Mean
360345330315300
95% Confidence Intervals
tc case 2






Cheatham Jr,
drilling, Engineering Geology,
Chi,
mining, International Journal of Mineral Processing,
Kanchibotla,
Proceedings Explo ’99,
Kojovic,
Minerals Engineering,
Konya, Surface Blast Design, pp 20–34, 118
Lopez Jimeno,
Drilling and Blasting of Rocks,
Michaux,
Minerals Engineering,
Nielsen,
optimisation of an integrated comminution system, in Proceedings
Fifth International Symposium on Rock Fragmentation by Blasting
,
Nielsen,
International Journal of
Rock Mechanics and Mining Sciences,
Oriard, Explosives Engineering, Construction Vibrations
and Geotechnology,
Ouchterlony,
©
Mining Technology,
Peres, Theory and Practice of Mineral
Roy,
Proceedings 14th Annual Symposium on
Explosives and Blasting Research,
Seccatore,
Materials Science Forum,
Workman,
Proceedings 29th
Annual Conference on Explosives and Blasting Technique, pp 131–140
Workman,
Proceedings 35th
Annual Conference on Explosives and Blasting Technique,
 







   

   

   

   


