Abstract
This research examines optimization of blasting parameters for economic production of granite aggregates in Ratcon and NSCE quarries located atIbadan,OyoState. Samples were collected from the study areas for the determination of rock density and porosity. Schmidt hammer was used for in situ determination of rock hardness. Uniaxial compressive strength of in situ rock was estimated from the values obtained from Schmidt hammer rebound hardness test and density determined from laboratory test. Blasting data were collected from the study areas for optimization. Multiple regression analysis using computer aided solution SPSS (Statistical Package for the Social Sciences) was used to analyse data obtained from the laboratory test, field test and the study areas. The estimated mean uniaxial compressive strength value of NSCE is 240 MPa and that of Ratcon is 200 MPa and their average densities and average porosities are2.63g/cm3,2.55g/cm3, 1.88% and 2.25% respectively. Eleven parameters were input into the multiple regression analysis to generate the models. Two parameters out of eleven input parameters such as geometric volume of blast (Y1) and number of boulders generated after blasting (Y2) were dependent variables and the remaining nine such as X1 (Drill hole diameter), X2 (Drill hole depth), X3 (Spacing), X4 (Burden), X5 (Average charge per hole), X6 (Rock density), X7 (Porosity), X8 (Uniaxial compressive strength) and X9 (Specific charge) were input as independent variables. The results of the models show that out of the nine independent variables seven of them that is X1 (Borehole diameter), X2 (Borehole depth), X3 (Spacing), X4 (Burden), X5 (Average charge per hole), X8 (Uniaxial compressive strength) and X9 (Specific charge) have significant contribution to the models while X6 (Rock Density) and X7 (Porosity) have insignificant contribution they are therefore automatically deleted by the SPSS. The result of the models developed for the optimization reveals that blasting number 5 gives the required product at lowest possible cost. From the result, the cost of secondary blasting has been reduced and volume of the blasted rock has been increased with low cost of explosives, the parameters that give this result have been chosen as optimum parameters.
Highlights
Efficiency of blasting operation in underground and surface mines determine to a large extent utilization of equipment, productivity and economics
Model 1 The value of R2 is 0.984 and the adjusted R2 is 0.979 (Table 8) showing that nine predictors entered in the regression analysis account for 98.4% of the variation in the geometric volume of blasted rock, while the F change is 193.239 (Table 8) and is much greater than 1, this shows that the model is significantly better at predicting volume of rock blasted rather than using means as a guess
The value of R2 is 0.876 (Table 10) showing that the nine predictors entered in the regression analysis account for 87.6% of the variation in number of boulders generated, while the F change is 22.192 (Table 10) and this is greater than one (F > 1), this shows that the model is significantly better at predicting the number of oversize generated after blasting rather than using means as a guess
Summary
Efficiency of blasting operation in underground and surface mines determine to a large extent utilization of equipment, productivity and economics. Proper fragmentation of blasted rocks and coal improves the efficiency of downstream operations, viz. An increase in the degree of fragmentation will give the loading equipment a higher rate of productivity. This will result in lower costs per ton or cubic yard moved. The effect of wear and tear will decrease, giving lower operating cost per hour. Under similar conditions of haul, lift, size and type of truck, and haul road condition, truck production per hour will increase with greater degree of fragmentation due to faster shovel or loader loading rates and a decrease in bridging at the crusher.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
