SELECTION OF EXPLOSIVE COMBINATION FOR OPTIMAL BLASTING FOR GRANITE AT DANGOTE QUARRY,IJEBU- IGBO, OGUN STATE,NIGERIA.

Abstract

The selection of explosive combination for optimal blasting was conducted in Dangote Quarry, located in Ajebandele village, Ijebu Igbo to eliminate the problem of poor rock fragmentation during blasting in the quarry. The properties (specific gravity, porosity, hardness, and uniaxial compressive strength) of the rock were determined by using appropriate American Society for Testing and Materials (ASTM) and International Standard of Rock Mechanics Standards (ISRM). The specific gravity of the rock as determined from the density was 2.705, the porosity of the granite deposit was found to be 0.94 %, the rock hardness as obtained using the L-type Schmidt Hammer was 43.94 while the average compressive strength of the rock was found to be 83.05 MPa. The following explosives: Cast Booster, Super Power 90, Solar Gel, Bulk Emulsion 201, and Ammonium Nitrate Fuel Oil mixture (ANFO) were combined in different proportion. A total of 15 blasting operations were carried out. The spacing of 2.25 m, burden of 2.0 m, hole diameter of 85 mm, and stemming height of 1.0 m were constant in the course of carrying out the research, while the Average hole depth ranges from 9.8 m – 10.5 m and the number of blasted holes ranges from 55 holes to 147 holes. Three of the fifteen explosives combination gave best fragmentation. The explosives combination of the threeThe selection of explosive combination for optimal blasting was conducted in Dangote Quarry, located in Ajebandele village, Ijebu Igbo to eliminate the problem of poor rock fragmentation during blasting in the quarry. The properties (specific gravity, porosity, hardness, and uniaxial compressive strength) of the rock were determined by using appropriate American Society for Testing and Materials (ASTM) and International Standard of Rock Mechanics Standards (ISRM). The specific gravity of the rock as determined from the density was 2.705, the porosity of the granite deposit was found to be 0.94 %, the rock hardness as obtained using the L-type Schmidt Hammer was 43.94 while the average compressive strength of the rock was found to be 83.05 MPa. The following explosives: Cast Booster, Super Power 90, Solar Gel, Bulk Emulsion 201, and Ammonium Nitrate Fuel Oil mixture (ANFO) were combined in different proportion. A total of 15 blasting operations were carried out. The spacing of 2.25 m, burden of 2.0 m, hole diameter of 85 mm, and stemming height of 1.0 m were constant in the course of carrying out the research, while the Average hole depth ranges from 9.8 m – 10.5 m and the number of blasted holes ranges from 55 holes to 147 holes. Three of the fifteen explosives combination gave best fragmentation. The explosives combination of the three blasts (5, 6, and 8) is made up of Cast Booster, Super power 90, and Ammonium Nitrate Fuel Oil (ANFO) mixture. The percentage of each of the explosive in the combination is 1.1%, 30.58% and 68.61% for blast 5; 1.09%, 18.1%, and 81.85% for blast 6, and 1.08%, 17.9% and 81.52% for blast 8. The Explosive Combination of blast 6 and blast 8, with lower explosive cost per ton of blasted materials, was selected as the appropriate explosive combination for optimal blasting operation in the study area. blasts (5, 6, and 8) is made up of Cast Booster, Super power 90, and Ammonium Nitrate Fuel Oil (ANFO) mixture. The percentage of each of the explosive in the combination is 1.1%, 30.58% and 68.61% for blast 5; 1.09%, 18.1%, and 81.85% for blast 6, and 1.08%, 17.9% and 81.52% for blast 8. The Explosive Combination of blast 6 and blast 8, with lower explosive cost per ton of blasted materials, was selected as the appropriate explosive combination for optimal blasting operation in the study area.