Mining Engineering

EVALUATION OF ROCK PROPERTIES FOR OPTIMIZATION OF FRAGMENTATION QUALITY IN SOME SELECTED QUARRIES

Sun, 01 Aug 2021 00:00:00 GMT

EVALUATION OF ROCK PROPERTIES FOR OPTIMIZATION OF FRAGMENTATION QUALITY IN SOME SELECTED QUARRIES AKEREDOLU, OLUWAFEMI JOSHUA This work deal with evaluation of rock properties and fragmentation sizes to predict fragmentation quality. Rock fragmentation, which is the fragment size distribution of blasted rock material, is used in the mining industry as an index to estimate the effect of bench blasting. Rock samples collected from three quarry locations were used for point load strength index, Uniaxial Compressive Strength, slake durability test and rebound hardness value were determined. Split software was used to determine the fragment size distribution and modified Kuz-Ram methods were used for fragmentation prediction. The mean values for Uniaxial Compressive Strength are 121.376 MPa, 129.2 MPa, 119.048 MPa for Samchase Quarry, F.M. Quarry and F.C.C Quarry respectively. The mean values for the point load were 11.135 MPa, 12.80 MPa, 10.50 MPa for Samchase quarry, F.M quarry and F.C.C quarry respectively. The slake durability index values reduce generally for all the quarries for both wet and dry samples. The difference was less than four for all the quarries. Ten readings were recorded at the three quarries for determination of rebound hardness values for the rocks. The mean rebound hardness values are 44.4 for Samchase Quarry, 48.2 for F.M Quarry and 42.3 for F.C.C Quarry respectively. The fragments were compared to the gape of the crusher, 0.1 meter was said to be undersize, and 0.6 meter above was said to be oversize. The average fragment sizes varied for the blasts for all the quarries. A general trend of under estimation of the undersize (< 0.1 meter) and over estimation of oversize (≥ 0.6 meter) was observed using Modified Kuz-Ram models as compared to the Split image analysis obtained on the field. A software was design compute for both blast design and fragmentation prediction, the software was design using java programming language, the software compute and gives result to users within few seconds. The rock properties for the three quarries revealed that the rocks are strong and classified as high strength rock. This mean that a high powder factor and high strength explosives will be required for the fragmentation and the rock material is durable.

EVALUATION OF THE SUITABILITY OF BEKUMA MARBLE DEPOSIT FOR DIMENSION STONE PRODUCTION

Tue, 01 Feb 2022 00:00:00 GMT

EVALUATION OF THE SUITABILITY OF BEKUMA MARBLE DEPOSIT FOR DIMENSION STONE PRODUCTION JIMOH, Fatai Kolawole This research was carried out to assess the suitability of Bekuma marble deposit for dimension block production. The reserve of the deposit was evaluated using rectangular method of reserve estimation and tested for physical, mechanical and chemical properties, as well as economic viability. In the study, the tests that were carried out included; porosity, water absorption, slake durability, uniaxial compression and the X-ray diffraction analysis. The results of the analysis from the two formations were compared with each other to project the economic feasibility of the research work. The reserve of the Bekuma formation study was estimated to be 79.3 x 106 tonnes. The results of formation I for Uniaxial Compressive strength, porosity, water absorption, Slake durability were; 172 MPa, 0.502%, 88.7 and 89.3% respectively. Formation two results for Uniaxial Compressive Strength (UCS), porosity, water absorption and slake durability were: 136 MPa, 0.868 %, 36.32 and 52.1 % respectively. The discontinuity mapping carried out on the two formations revealed that, Formation I had less and scattered micro fractures with wide spacing. Formation I marble had a sound economic standing with inexhaustible reserves, dense strength, white and blackish aesthetic appearance. Formation II showed intense fracturing and brittleness which makes it unsuitable for dimension block production. Analytical dependences have been specified making it possible to evaluate the marble deposit reserve, mechanical characteristic and the suitability of the deposit for dimension block production. The studied marble deposit revealed two formation results from diagenesis differentia. The test quarry carried out by development of a 50m by 50m size using Dozer D8k and Excavator 320BL. A diamond cutting machine was used to cut the formation vertically and horizontally. A test block of 4m by 3m by 2m was achieved. The cut section of the formation further confirmed the suitability of the formation for dimension stone production. Bekuma marble formation I analytically suit production of dimension block. This study helps to create alternative use for the deposit and means of raw material for tiles and other slab manufacturing industries. M.ENG THESIS

NUMERICAL INVESTIGATION OF THE INFLUENCE OF ROCKFALL ON CIVIL STRUCTURES IN SELECTED SOUTHWESTERN STATES, NIGERIA

Sun, 01 Aug 2021 00:00:00 GMT

NUMERICAL INVESTIGATION OF THE INFLUENCE OF ROCKFALL ON CIVIL STRUCTURES IN SELECTED SOUTHWESTERN STATES, NIGERIA OMOEGUN, SUNDAY OLATUNBOSUN Influence of rock fall on civil structures within Southwestern Nigeria was investigated. In this study, seven highly susceptible rockfall locations near civil structures were selected, Dips 7.0 and RocFall 8.0 (RocScience software) was used for kinematic and numerical simulation model to investigate the influence of rockfall. Based on the field investigation, the study areas are characterized by hanging rocks and jointed rocks marking the areasprone to rockfalls. Rock properties of rocksunder investigation ranged from 46.0 – 50.4 and 134.10 MPa - 153.96 MPa. The kinematic analysis results indicated that the outcrop in the fifth location will not experience any form of instability failure, since the analysis showed no state of criticality on any of the discontinuities. The analysis for other locations clearly indicated that the outcrops present in the first, second, third, fourth, sixth and seventh locations have minimal level of criticality to experience either planar or wedge sliding failure. The analysis of the seventh location further revealed that the first joint set for toppling failure has criticality of the discontinuities equals the percentage critical point at which failure will occur and has a higher likelihood of toppling failure occurrence. Rockfall movement trajectory and bounce height were modeled with their corresponding translational velocity and kinetic energy for predicting the influence of rockfall. Location 6 has the maximum bouncing height of 26.3 m and location 4 has the minimum bouncing height of 1.9 m as compared to other locations. The results of the rock fall simulation model established that the study areas are at risk of rock falls influence capable of causing mortality and damage to civil structures, as summarized in Table 4.2 the total kinetic energy of falls observed ranged from low (< 30 kJ) to medium intensity hazard level zones (30 - 300 kJ). In conclusion the research was able to establish the degree of damage of rock fall on civil structure base on rock fall hazard intensity classification. It is recommended that further research should be done in all parts of the country to establish rock fall hazard map for Nigeria. The residents of these study areas should be cautious of rockfall occurrence and adequate barriers are required to prevent rock fall vulnerability/consequence.