Statistical Analysis on Physico-Chemical Properties of Some Nigerian Clay Deposits

Clays are among the most essential industrial minerals due to their unique physicochemical properties and versatile usage. This paper used Statistical Package for Social Sciences (SPSS) software to characterize five clay deposits for their physical and chemical compositions. The package, was employed to carry out the Analysis of Variance (ANOVA) by Post-Hoctambane multiple comparisons and Kristal Wallis at 5% confidence level for the fand t-tests respectively. The analysis of variance of the chemical components of the samples by post-hoc (f8, 36 = 52.40, p < 0.05) showed that significant difference exist between the average concentration means. While the Kristal Wallis one sample t-test (T8, 37.38 and p < 0.05) showed a great degree of significant difference in the p-values of the means of SiO2 and Al2O3. Pearson bivariate correlation statistical tool was also used to establish if significant positive interrelationships exist between the parameters in each site of the clay samples at (p < 0.01 and p < 0.05). The result of the correlation indicates a very significant, strong and positive coefficient p-values above 0.900 between the chemical and physicalproperties. Pearson bivariate correlation coefficient between the chemical and physical parameters of the clay samples indicates very significant, strong and positive correlations with p-values above 0.900 at (p < 0.01 and <0.05). The overall physicochemical results indicate that most of the clay samples will meet the requirements for some industrial applications with minimal processing.

planar sheets. The tetrahedral and octahedral sheets form a polymeric alumino-silicate layer that is mostly crystalline in structure. Impurities such as Fe 2 O 3 , TiO 2 , K 2 O and Na 2 O vary among clay samples from the different locations. Clay minerals share a basic set of structural and chemical characteristics, yet each clay mineral has its own unique set of properties that determine how it will interact with other chemical species [1].
The application of clay materials is influenced by their physical and chemical properties which determine their suitability for specific usage. The geographical location for each clay materials confer unique physico-chemical properties which ultimately determines the type of material produced and its application [2]. Specific physical and chemical properties of clays such as kaolin are also dependent on the environment of deposition, geological origin, geographic source and the material method at the end of processing [3]. The basic physical and chemical properties of clay materials are widely used in both academic and industrial fields. These properties may vary under the influences of both natural processes and human disturbances [4].
Clays are abundant and readily available. They also possess distinct adsorptive characteristics from one origin to another. The adsorption characteristics depend on the chemical and mineralogical composition as well as on textural, structural, and morphological properties [5]. Plasticity is also one of the most important clay properties that are related to different parameters. The most disaggregated clay minerals with major ionic exchange capability are more often plastic in nature. Montmorillonitic minerals are most plastic, than illitics, and least kaolinitics [6]. Clays and clay minerals such as montmorillonite, vermiculite, illite, kaolinite, and bentonite are widely used in process and petroleum industries, engineering and constructions, environmental remediation, ceramics and refractories, pharmaceuticals and agricultural sectors [7].
Nigeria has large quantity of clay minerals that are widely spread across the country. Some of the studies conducted on Nigerian clays are reported in many literatures [8] [9] [10] [11] [12]. This study evaluates the physical and chemical properties of the clay deposits in selected locations in Plateau State, Central Nigeria using statistical analysis.

Study Site
The study sites referenced in this research are all located in Plateau State, Central Nigeria. The deposit sites include RarinSho (RC), Major Porter (MP), Kwi (KC), Wereng Camp (WC) and Naraguta (NC). The study areas are bounded between latitudes 8˚30 E and 9˚00 E and longitudes 9˚30 N and 10˚00 N as shown in

Sample Collection and Determination
The samples were obtained from underground local mines 10 -20 cm beneath the soil surface. Ten different points within each deposit collected was by randomized sampling. In addition, 5 kg of fresh samples in lump form were obtained randomly from ten different points within each deposit from underground local mines pit at the depth of 10 -20 cm. The samples were air-dried for several days and crushed using a set of Denver crushers by Denver Equipment Company England. Each crushed sample was thoroughly mixed, coned and quartered. Two opposite composite representatives were obtained and consequently milled and pulverized. These were packaged in small polyethene bags as representatives of the samples for the required tests [11].

Chemical Analysis
The chemical compositions of the pulverized samples were determined by Energy Dispersive X-ray Fluorescence (EDXRF) of the model PW4030 X-ray photome-Journal of Materials Science and Chemical Engineering ter that uses a rhodium anode tube. The sample film was placed firmly in a waxed and gold plated sample holder. The Energy Dispersive patterns were obtained with the help of a computer attached to the instrument and each compound recorded in percentage [13].

Loss on Ignition
Loss on ignition was determined according to the Lechler and Desiletes method, [14]. The samples were oven-dried at 110˚C. Then 1 g of the sample of clay was placed in preheated, cooled and pre-weighed silica crucibles and heated to 1000˚C in a furnace for an hour. The crucibles and contents were removed, cooled in a desiccator to room temperature and weighed again. The loss in weight was calculated.

Plasticity Index of Clay Samples
The Atterberg plasticity method prescribed by [15] was used to calculate the plasticity index of the clay samples from their respective liquid and plastic limits determined.

Particle-Size Analysis
The particle size test was carried out by using the standard Hydrometer method [16]. 50 g of milled oven-dry clay was weighed into a 250 cm 3 beakers and mixed with 100 cm 3 calgon, then allowed to soak for 30 minutes. The mixed suspension was transferred into a sedimentation cylinder and filled up to mark point with distilled water.
The hydrometer was inserted into the mixture in the cylinder and the readings were taken after interval of 40 seconds twice. After 2 hours, another hydrometer reading and temperature were recorded. After 40 seconds and 2 hours, all the sand and silt particles would have settled and only clay will remain in suspension. The percentages of silt and clay were then calculated and the interpretation of result was made by using a textural triangle.

Drying and Firing Shrinkage of Clays
The clay drying and firing shrinkages were determined from brick bars prepared using a mechanical hydraulic press (model D-7064 Paul Weber) with its accessory moulds and the method adopted was [17].

Statistical Analysis
The statistical tools employed to carry out the data analysis of this study were the

Physicochemical Characteristics of the Clay Samples
The results of the chemical and physical analysis of RarinSho (RC), Major Porter (MP), Wereng Camp (WC), Kwi (KC) and Naraguta (NC) clay samples are summarized in Tables 1-3 respectively. The chemical properties of the samples were determined statistically by analysis of variance (ANOVA) at (F 8 , 36 = 52.40, p < 0.05) and Krystal Wallis one sample t-test (T 8 , 37.38, p < 0.01). The results of chemical analysis shows the different oxide components that indicate also the variations in the means of the concentrations of the compounds contained in the studied clay bodies.
The ANOVA in Table 1 showed that significant differences exist between the average means of the concentrations of the oxides of the different samples except for few minor constituents whose values are similar. The Krystal Wallis one sample t-test result of the randomized block design model used for major and trace oxides shown in Table 2    The results of the Pearson bivariate correlation coefficient determined between the chemical and physicalproperties of the clay samples in Tables 4-8 showed very significant, strong and positive correlations. Most of the correlation values fall within the range of 0.900 and above but less than unity in all the samples.

Correlation Associations between the Clay Parameters
Interrelationships in clay chemical and physical properties were assessed for each sample site by Pearson Bivariate correlation analysis. Multiple and very strong significant correlations were observed and selected. The correlations determined for RarinSho clay sample shown in Table 4 were highly significant. Very high significant interactions were observed between silt and PL (r = 0.953), K 2 O and CaO (r = 0.942), Quartz and pH (r = 0.925), and Al 2 O 3 and PL (r = 0.903) all at (p < 0.05). There was also a moderate level of significant correlation between TiO 2 and Na 2 O (r = 0.896) at (p < 0.05). The chemical analysis of this sample showed that the value of SiO 2 was much higher than normal, chiefly due to the quantity of silt and quartz present from its size analysis. The association also indicates that the content of silt and Al 2 O 3 contribute positively to the increase of the plastic limit of the sample. The site also indicates that the increase in the concentration of K 2 O resulted to the slight rise of that of CaO. Similarly, some interrelationships occurred between the physical and chemical properties of Major Porter clay sample. The most positive significant correlations amongst the oxides concentration was observed between Fe 2 O 3 and TiO 2 (r = 0.995) at (p < 0.01) shown in Table 5. Significant correlations were also observed between Fe 2 O 3 /TiO 2 and clay (r = 0.977, 0.972), also at (p < 0.01), and K 2 O and Clay (r = 0.952) at (p < 0.05). Clay and PI (r = 0.950) also associated at (p< 0.05). There was also a strong double significant association between Fe 2 O 3 /TiO 2 and the plastic index of the sample at (r = 0.958; p < 0.05). The sample in this site was notably observed to contain an appreciable amount of Fe 2 O 3 and SiO 2 . The low LOI value of the sample is attributed to the amount of quartz obtained from its size analysis. Table 6 shows a very strong significant interactions between       as impurities in the sample. The high concentration of TiO 2 in the sample is due to its close association to the small quantity of the silt.
The most significant and very strong positive relationship amongst the properties in Kwi clay sample was between PL and pH (r = 0.991, p< 0.01). There was also a strong correlation between clay and quartz (r = 0.953, p < 0.05) and between quartz and PI (r = 0.944; p < 0.05) as shown in Table 7. The sample also indicated numerous negative correlations at different strengths but not considered. The interrelationship in this deposit has shown that the sample has the lowest pH in Table 3 contributing to the positive increase of its PL value.

Conclusion
The