Description of the study Area
MAN HARDI Nig. Ltd. Quarry is situated on Latitude N008034.291, Longitude E0040 34.771 in Ilorin South Local Government Area of Kwara State. The Quarry has a land area of about 4000m2 and is at about a distance of 2.4km from Kangile, the nearest village. The site overview comprises of granite deposit, and it is surrounded by thick bushes, trees and stream. A fire boundary clearance separates the mining area from the surrounding vegetation. Figure 1 shows the map of Kwara State, Nigeria indicating the studied site.
Granite samples obtained from the MAN HARDI Quarry were brought to laboratory for further analysis. The granite samples were carefully selected for the following analysis: XRF, Hardness, Polish value, compressive strength, oxidation properties, specific gravity of granites.
X-ray Fluorescence (Xrf)
X-Ray Fluorescence is used to analyze the elemental composition of samples which is based on surface analysis. It is the emission of characteristic ‘secondary’ (or fluorescence) X-rays from a material that has been exited while bombarding with high energy X-rays or gamma rays. The method employed in this analysis is the energy-dispersive analysis (ED-XRF) and the machine model used to determine the basic chemical composition of the sample is the Shimadzu EDXRF-702HS
The sample is irradiated with X-rays within the instrument. If an X-ray photon is absorbed by the sample of sufficient energy then an electron is emitted via the photoelectric effect resulting in an electron hole in the atom. An inner shell electron will then fall back to fill this hole resulting in the release of electromagnetic energy with a frequency characteristic of the element present.
A metallic filter, which was 100-m-thick titanium or 50-m-thick zirconium, was attached to the Rh x-ray tube. The aluminum collimators of inner diameters of 6 mm and 3 mm were attached to the x-ray tube and the detector, respectively. The x-ray tube and the detector were tilted to 45 degrees. The detector and the sample holder were placed on a Z-stage and to adjust the distance from the point of the detector to the sample surface. The external diameter of the sample holder was 44.5 mm (inside diameter: 40.5 mm) and height was 25.5 mm. The thickness of sample could be changed depending on the volume put in the sample holder
All measurements were carried out on an energy dispersive X-ray fluorescence spectrometer Shimadzu EDXRF-702HS operated at 40 kV and 18 mA. The current was automatically adjusted (maximum of 1 mA). A 10 mm collimator was chosen. The counting time was 100 seconds for all measurements. The intensity of element Kα counts per second (cps/µA) was obtained from the sample X-ray spectrum using the Shimadzu EDX software package.
Weighing Of The Samples
The Ohaus Digital weighing balance (model Ohaus AX22021 E-US) is a standard laboratory applications to ensure solid weighing performance and accurate repeatable results. It has a capacity of 2,200grams and a readability of 0.01gram (10miligrams).
The Form Test Seidner (Model GMBHD7940) is a system which produce high quality, high degree of accuracy and reproducibility of text results. It is used to determine the compressive strengths of materials.
Rock Well Hardness Testing
The Rock well hardness testing machine (Model: GMBH3806) is a device that indicates the hardness of a material usually by measuring the effects on its surface of a localized penetration by a standardized rounded or pointed indenter of diamond carbide or hard steel.
The Road Wheel polishing machine is a great machine for grinding, smoothing and polishing process, it produce a high quality, repeatable finishing solution to achieve a highly polished results.
The Syno-electro –magnetic machine corporation (FMC) is a machine used to repolished materials with oxidized surface with variable speed of 250rpm (maximum) after the materials are removed from the machine, cleaned with oxygen damp paper of grade one and dried with pressurized air.
Chemical Analysis By Xrf
The sample was ground to a fine powder (to obtain a homogenous sample) using a vibration grinding mill with a steel milling. It was sieved through a 200-mesh sieve and dried to constant weight in a furnace at 110°C.
XRF was performed on sample prepared in the form of glass disks with a sample/melt ratio of 0.5/5; Li2B4O7 was used as the melt. The reference materials GSS8 and BCS-CRM 354 were used to produce standards; mixtures of these with an oxide content including that of the samples to be analyzed were used to produce a calibration curve. The reference materials were mixed with a 5% Au/Pt ZGS glass rod and melted in a furnace at a temperature of 1100°C for 15 min. The melt was taken from the furnace and stirred after 10 min and then replaced to eliminate bubbles. It was then poured into a Pt/Rh 30-mm diameter mold to form a glass disk, of 30 mm diameter and 9 mm thickness were used for the analyses.
Determination Of Percentage Loss On Ignition
Approximately 1.0g of sample was weighed in a platinum crucible at a temperature of 25°C, this material was heated at a temperature between 900-1,000°C, cooled and weighed, W1. The loss in weight was checked by a second heating at same temperature for 5 mins and the content reweighed. This process was repeated until a constant weight was attained, and recorded as W2. The loss in weight was recorded as the loss in ignition. Percentage loss on ignition was calculated as follows:
W3 = W1 – W2,
% loss of ignition = (W3 x 100)/W,
W = weight of sample taken.
W3 = Loss in weight.
plastics or stainless steel.
The hardness test was carried out on the sample of dimension 20mm x 20mm x 20mm using a Rockwell Hardness Testing Machine (Model: GMBH3806) with steel ball as the indenter. The indentation was carried out on five randomly selected points on the surface of each sample, average of the hardness value was taken and reported.
Polish Value (Pv) Test
The polish Value test was carried out on the samples to determine the display of good abrasiveness and yielding attractive color tints.
Compression stress was measured using form test seidner, model GMBH D7940 compression machine, Riedlingen - West Germany. Compressive stress was applied uniaxially to sample of dimension 20mm x 20mm x 20mm with a crosshead speed of 20 mm per minute to determine the behavior of the composites under a compressive load.
The oxidation test was carried out to determine the rate of decomposition or break down of the rock samples surfaces when exposed to air, heat, and acidic solvent before and after polished. The procedure used for the test includes cutting of sample A, B and C of dimensions 20mm X 20mm X 20mm were polished before exposed to prepared solution of tap water, dilute hydrochloric acid (HCL) and oil. These samples were then left exposed to atmospheric condition for four days. After this the samples were then re-introduced into a synon-electro-magnetic machine corporation (FMC) with variable speed of 250rpm (Maximum) to allow re polishing of the oxidized surface. Finally, the samples were removed from the machine, cleaned with Oxygen damp paper of grade one and dried with pressurized air. The dried samples were then observed under a Nikkonophiphot polarized microscope for any damage to the already polished surface such as peeling due to the corrosive nature of the solution of acid, air and oil.
Specific Gravity Determination Of Samples
20 g of sample A was weighed (W) using Ohaus Digital Weighing Balance (Model: Ohaus AX2202/E- USA) and was charged into 100 ml measuring cylinder of known volume of water refers to as initial volume (Volume (V2) of water was measured and the difference in the initial volume and final volume of water was noted as the displacement. Specific gravity was calculated using equation (ISRM, 1981)).
These were repeated for other samples