ASSESSING THE RELATIONSHIP BETWEEN BLAST DESIGN ANDFRAGMENT SIZE DISTRIBUTION ON CRUSHER EFFICIENCY

Abstract

Large number of the oversized boulder requires high cost and effort for secondary blasting in addition to that, accidental throw of the oversize boulders in the crusher opening causes downtime in the crusher, which creates a bottleneck in the production. This research was carried out to assess the relationship between blasting design and fragment size distribution on crusher efficiency. To achieve the aim of the research, rock samples and blast design information were collected at four different locations at JIGOM Nigeria Enterprise, Uzeba, Edo State. Result from the laboratory analysis carried out to determine the hardness of the rock shows an average Uniaxial Compressive Strength value of 211 MPa for the deposit. Using Microsoft Excel, the blastability index and the characteristics size for the four locations (location 1, 2, 3 and 4) inside the quarry was determined. Location 1 to 3 have equivalent blastability index of 6.33 while location 4 has blastability index of 6.48. The characteristics size for location 1, 2, 3 and 4 are 0.65 m , 0.27 m, 0.19 m and 0.15 m respectively. Through the Rosin-Rammler model, probable fragmentation result for the four different locations were obtained. The results indicated that the percentage of oversize at location 1, 2, 3 and 4 are 44.7%, 32.5%, 13.7% and 2.6% respectively. Optimum fragmentation was obtained at location 4 as it has the highest percentage of range (96.6%) passing through the crusher. The plot of percentage passing against fragmentation sizes indicated that 68% of the fragmented rocks will be able to pass through the crusher gape at location 1, while at location 2 percentage passing is 99.6%. Locations 3 and 4 have equal percentage of passing of 85.7%, 96%. Also, only location 3 and 4 produced mean fragment (50% passing) that fall within the targeted fragmentation size. The efficiency of the crusher at the four locations, 1, 2, 3 and 4, are 30.5%, 37.5%, 54.7% and 82% respectively. This shows that location 4 has the highest crusher efficiency due to its highest percentage of optimum size predicted for that location. It is therefore recommended that the design parameters used at location 4 are adopted for blast design planning at Uzeba quarry to bring about efficiency in the downstream process of the quarry. This has help the company to solve the problem associate with down time in crusher and it lead to increase in production.