Journal of Mining World Express (MWE) Volume 4, 2015 www.mwe‐journal.org Doi: 10.14355/mwe.2015.04.003
Evaluation of Suitability of Some Selected Rocks for Dimension Stone Quarry in Akure, Ondo State, Nigeria Afeni Thomas Busuyi, 2Moshood Onifade, 3Omotayo Bolaji Raphael
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Department of Mining Engineering, Federal University of Technology Akure, PMB 704, Ondo State Nigeria
1, 2,3
E‐mail: tbafeni@futa.edu.ng; moshoodonifade@yahoo.com Abstract The evaluation ofrock suitability for dimension stone quarry has been a thing of concern to the dimension stone industries. So, three granite rocks were selected in various locations in Akure, Ondo State, Nigeria. The locations are Iloyin, Oba‐ile and Apatapiti and on these outcrops,in‐situ tests were carried out on the outcrops and irregular rock samples were collected for laboratory tests. Schmidt hammer test and Scan line mapping for discontinuities analysis were done on site while sample test for density, specific gravity, average water absorption, point load strength and slake durability were done in the laboratory. The Apatapiti outcrop hasthe highest average density (3.12g/cm3), specific gravity (2.822) and water absorption value (0.84%), while the Iloyin outcrop exhibits the highest average durability (97.88%) and point load strength (5.79MPa), the Oba‐Ileoutcrop have the highest compressive strength (190MPa)and average Schmidt hammer hardness value (47.0). The three outcrops volumetric joint count, Jv estimated gave medium block sizes but in the case of block quality of the rockssubjected to evaluation Iloyin happens to be of poor quality while Oba‐Ileand Apatapiti outcrop have prospect ofproducing fair quality block. With the information fromthe assessment of block size, block quality and mechanical and physical properties for the rocks consideredin this paper work, it was observed that these three selected outcrop are not good for dimension stone quarry but can be quarried as aggregate stone for construction purposes. Keyword Dimension Stone, Block Size, Block Quality, Mechanical and Physical Properties
Introduction Evaluation of rock suitability for dimension stone quarry is a good practice, especially in the most developed stone producing countries. It is imperative to perform thorough geological, engineering, and technical investigation before opening a dimension stone quarry, it is however imperative to know that not all natural facing stones qualify for the production of dimension stone (Lapedes, 1978). The selection of dimension stone purely on aesthetic features is hindered with the danger it may bring in application. However, the need to subject the rock material to load and test should always be considered first, as it should be ensured that the stone supplied is equivalent to the original selection criteria, and that it is appropriate for the intended purpose and safe to be used. Thus, the rock sample is to be subjected to various physical and mechanical tests which are: density, specific gravity, porosity, durability index, water absorption, Schmidt hammer strength, uniaxial compression and tensile stress in accordance with recommended standard.Besides, meeting the desired physical, mechanical and aesthetic properties, the rock must be relatively free of fractures so that it can be split or cut from a quarry face in large multi‐tonne blocks and transported to the processing plant (Peter et al., 1984).In exploratory work, colour and features of ingredients define decoration criteria i.e. anaesthetic properties, the physical and mechanical properties defines technical criteria which implies behaviour under application, geological criteria describesthe discontinuities properties peculiar for determination of block sizes and block qualities in rock suitable for exploitation of dimension stone (Tomasicet al.,1994). All the stated criteria dictate whether or not a dimension stone deposit is suitable for dimension stone product.Sonnezetet al.,(2004), stated that several researchers have carried out research work on the fracture patterns of rock mass to assess the probability of having appropriate block size that will be acceptable and at marketable quantity.The joints geometrical parameters and their networks when measured is a very relevant factor for identifying suitability of rock mass for dimension stones production.The block sizes can be evaluated using either empirical methods or numerical methods according to Palmstrom(2005).
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