J. Nig. Soc. Phys. Sci. 4 (2022) 27–33 Journal of the Nigerian Society of Physical Sciences Mechanical Evaluation and Minerals Phases Identification of Fine and Coarse Okelele Block Clay Composites for Furnace Lining Application Yusuf Olanrewaju Saheed, Mufutau Abiodun Salawu∗, Aderemi Babatunde Alabi Department of Physics, University of Ilorin, Ilorin, Nigeria Abstract The suitability of fine and coarse Okelele clays as refractory raw materials for furnace lining application was investigated. The clay samples were crushed and pounded with a mortar and pestle to a particle size of 20 microns. 230 g each of fine clay was mixed with 50 mls of water inside a bowl and stirred thoroughly to form homogenous plastic paste. 10 g, 15 g, 25 g, 35 g and 45 g of coarse clay were added respectively to the 230 g of homogenous fine clay paste in different container. The fine and coarse clays composites weighing 240 g, 245 g, 255 g, 265 g and 275 g were respectively put in a mold of dimension 3 x 5 x 6 cm and air dried for 7 days. The samples were fired at temperature of 1200 oC for five hours using Carbolite Furnace. After cooling, the fine and coarse clay composites of 240 g and 245g were broken by the heat and composites blocks 255 g, 265g and 275g were hardened and remove for compressive test analysis. The fine and coarse clays were characterized using X-ray Diffractometer PW 1830 for minerals phases’ identification. The result of XRD shows that the clay was majorly composed of Quartz and Kaolinite with the traces of other minerals such as Smectile, Illite/Mica, Albite, Jarosite, Gypsum and Pyrite. The Kaolinite contains aluminum silicate (Al2O3·2SiO2) and Quartz has the silicon and oxygen atoms. The compressive strength test result judged the 275 g fire block of clays composite the best with the maximum force breaks of 7652 N with deflection of 3.734 mm and Young Modulus of 212 N/mm2 for the time to failure of 22 seconds. The results proved that Okelele clays are suitable as refractory material for furnace lining application. DOI:10.46481/jnsps.2022.252 Keywords: Okelele clays, Kaolinite, Quartz, Refractory materials Article History : Received: 13 June 2021 Received in revised form: 14 October 2021 Accepted for publication: 19 October 2021 Published: 28 February 2022 c©2022 Journal of the Nigerian Society of Physical Sciences. All rights reserved. Communicated by: S. J. Adebiyi 1. Introduction Nigeria is rich with abundant mineral resources but these resources have not been sufficiently explored and used. Clay is a naturally occurring material composed of layered structures ∗Corresponding author tel. no: Email address: salawu.ma@unilorin.edu.ng; abideen2004@gmail.com (Mufutau Abiodun Salawu ) of fine-grained minerals which reveal the property of plastic- ity at appropriate water content and permanently hard when fired [1]. Clay as a mineral that consist of silica (SiO2), Alu- mina (Al2O3), water (H2O), and other impurities are alumino- silicate, mostly answerable for its thermal property of refrac- toriness which applicable in the manufacturing of several re- fractory products. It is earthen and soil with intricate inorganic blend, whose structure diverges and generally depends on the environmental and geographical position [2]. 27 Saheed et al. / J. Nig. Soc. Phys. Sci. 4 (2022) 27–33 28 High demand for refractory materials for Furnace build- ing and other related high temperature processes is enormous. Nigeria spends more than 2.27 billion naira yearly on the impor- tation of refractories for industrial application [3]. The applica- tion of clay composites as a refractory material depends sever- ally on its thermal property of refractoriness, chemical compo- sition, mechanical and physical properties [2], [5-13]. Refrac- tory materials are inorganic materials containing the mixtures of oxides obtained from naturally occurring minerals capable of withstanding very high temperature conditions without crack- ing, deforming, softening or change in composition [3]. The good characteristic of a refractory is to provide basic thermal properties, support winding (electric resistance) and be able to hold solid or liquid metals without entering into any undesir- able chemical reaction with them. Thus refractory materials are characterized by the ability to withstand the heat, chemical at- tack, abrasion, impact, and shock caused by thermal stresses. The clays used for furnace linings in metallurgical indus- tries are classified as refractory clays. However, the degree of refractoriness and plasticity of any clay material is often influ- enced by the amount of the impurities contained in them [13]. The mechanical properties of different particle sizes of some impurities for some specific application had been investigated [14]. Chanchanga, Bida, Suleja and Zungeru clays deposits have better refractory and physical properties when compared with imported ones [3]. Some local clay deposits in other part of Nigeria have also been investigated with good results. Some of the clay deposits investigated for refractory application in- cludes but not limited to Dukku clay deposit in Gombe State, Onibode, Ibamajo, Ijoko in Ogun State and Are in Ekiti State [15]. The characterization of Otukpo clay in Benue State was also reported [16]. The economic circumstance in Nigeria as at today has ne- cessitated for the inward sourcing of locally available raw mate- rials across the country for domestic and industrial applications. Due to the aforementioned economic needs and the fact that the Okelele clay deposit in Ilorin, Kwara State is only used for lo- cal pottery by old women living around the area and building bricks by local bricklayer. The minerals phases’ identification and refractory properties of this particular clay deposit needs to be investigated. 2. Materials and Method The fine and coarse clay samples were collected from a de- posit in Okelele, Ilorin East local government area of Kwara state. The Molding iron bar, Mortar and pistol, Electronic weigh- ing balance, HT 4/28 Carbolite Gero Muffle Furnace Machine located at Geology Department, University of Ilorin, (0-3000 ◦C), XFS300 Testometric compression test machine located at Agricultural Biotechnology Laboratory, Department of Biotech- nology engineering, University of Ilorin and PW 1830 X-ray Diffractometer located at the Department of Geology, Univer- sity of Ibadan were used in this work. The clay samples were crushed and pounded with a mortar and pestle to a particle size of 20 microns. 230 g each of fine clay was mixed with 50 mls Figure 1. Shows the broken and unbroken Fired Block of Clays after firing of water inside a bowl and stirred thoroughly to form homoge- nous plastic paste. 10 g, 15 g, 25 g, 35 g and 45 g of coarse clay were added respectively to the 230 g of homogenous fine clay paste. The fine and coarse clays composites weighing 240 g, 245 g, 255 g, 265 g and 275 g were respectively put in a mold of dimension 3 x 5 x 6 cm and air dried for 7 days. The samples were fired at temperature of 1200 oC for 12 hours us- ing HT 4/28 Carbolite Gero Muffle Furnace (0-3000 ◦C). After cooling, the fine and coarse clay composites of 240 g and 245g were broken by the heat and composites 255 g, 265g and 275g were hardened and sound like a glass when tapped. Figure 1 shows the fabricated broken and unbroken fired block of clays after firing. 2.1. X-ray Diffractometer (XRD) Analysis XRD was used to identify the phase of minerals constituents of the clays. The fine and coarse clays were separately crushed and milled to fine particles and put in test tubes. The sam- ples were subjected to X-ray using the Philips PW 1830 X-ray diffractometer with a cu-anode at the “University of Ibadan” Ibadan, Oyo State. After the X-ray characterization of the sam- ples, mineral peaks were identified using XPert High Score plus Software. The background and peak positions were identified and based on the peak positions and intensities; a search-match routine was performed. 2.2. Compression Test The unbroken fired block of clays (255g, 265g and 275g) were subjected to mechanical compression test at the Civil En- gineering Laboratory of the University of Ilorin, Ilorin Kwara State, to show how these materials deform (elongate, compress, twist) or break as a function of applied load, time, tempera- ture and other conditions. The mechanical test was performed using XFS300 Testometric compression test machine. The ca- pacity of this machine is 10,000 pounds (tension and compres- sion). The samples of the given clay material took a rectangular shape which is unreformed (with no permanent strain or resid- ual stress), or original shape. 28 Saheed et al. / J. Nig. Soc. Phys. Sci. 4 (2022) 27–33 29 Figure 2. Testometric Compression Test Machine used Figure 3. Cracked Block of Clay during Compression Test 3. Results and Discussion Figure 4 and 5 show the XRD patterns of fine and coarse clays. The Debye Scherer equation was employed for the esti- mation of grain sizes of fine and coarse clays. Grain size g = kh βcosθ (1) Where k is the Debye Scherer constant (0.94) h = 1.56 x10−10m = 0.156nm β = (FWHM) Full width at half maximum (radians) θ = Peak positions (radians) The estimated grain sizes and mineral constituents of fine and coarse clays are shown in Table 1 and Table 2. Tables 1 and 2 give the results for the minerals phase identi- fication for the fine and coarse Okelele clays. The Kaolinite and Quartz are dominance in the mineral phase identifications for the fine and coarse Okelele clays composites. Kaolinite which is also called China clay, is the best refractory clay type and will not soften below 1750 ◦C. Kaolinite clays possessed little plas- ticity due to their large clay particles. The Kaolinite contains Figure 4. XRD Pattern of Fine Clay Figure 5. XRD Pattern of coarse Clay Al2O3·2SiO2. The pure kaolinite can be found at the site of its parent rock (primary clay) and when it has not been mixed with impurities, its refractoriness is great. The Quartz is a very hard crystalline mineral mostly found in nature contained the silicon and oxygen atoms. Quartz is the most conventional source of silica to be used for refractory production. The refractory made from Silica (Silica refractory bricks) possesses excellent ther- mal shock resistance at specific temperature range. The compressive strength test on 255 g, 265 g and 275 g fire blocks of clay composites were carried out to investigate the load carrying capacity of the fire blocks under compression using compression testing machine. This is important to deter- mine the compressive strength of fire blocks for its suitability as furnace lining. The materials behaviours under a load were determined. The maximum stress a material can withstand over a period under a load (constant or progressive) was determined to a break (rupture) or to a limit. These results are shown in Table 3, 4 and 5. 29 Saheed et al. / J. Nig. Soc. Phys. Sci. 4 (2022) 27–33 30 Table 1. Estimated grain sizes and mineral constituents of fine Clay Peak no. 2theta (rad) FWHM Grain Size (nm) Constituents 1 4.43 2.187 3.844597803 Smectile 2 8.46 5.038 1.672251355 Illite/mica 3 12.24 7.12 1.186799367 Kaolinite 4 13.56 5.097 1.660000572 Albite 5 15.38 3.167 2.677013045 Illite/mica 6 19.47 5.272 1.616958333 Clay mineral 7 20.43 2.187 3.90360038 Quartz 8 23.46 5.038 1.703266297 Kaolinite 9 26.24 7.12 1.211663863 Kaolinite 10 27.56 5.097 1.697242735 Quartz 11 28.38 3.167 2.736431091 Albite 12 30.47 5.272 1.651722605 Illite/mica 13 31.32 2.348 3.716247528 Albite 14 32.12 7.257 1.204777898 Illite/mica 15 34.04 4.328 2.030195653 Illite/mica 16 36.58 2.039 4.339821991 Clay mineral 17 38.433 2.147 4.144207588 Quartz 18 40.465 5.035 1.778423867 Kaolinite 19 42.245 7.123 1.264497493 Quartz plus Kaolinite 20 46.567 5.027 1.819527192 Quartz 21 48.382 3.164 2.91109195 Quartz 22 50.473 5.278 1.75982879 Quartz plus Kaolinite 23 54.436 2.157 4.380159907 Illite/mica 24 55.467 5.034 1.885640471 Quartz 25 60.245 7.125 1.363317463 Quartz 26 62.562 5.077 1.936374021 Kaolinite Figure 6. Force (N) against Deflection (mm) of 255 g fine and coarse fire block clay composites The 255 g block has the force break of 2632 N and deflec- tion break at 4.343 mm. The time to failure is 26.133 seconds for the Young Modulus of 174.476 N/mm2 among other param- eters (Table 3). The 265 g block has the force break of 1439 N and deflection breaks at 4.671 mm. The time to failure is 28.1 seconds for the Young Modulus of 94 N/mm2 (Table 4) while the 275 g block has the force break of 7652 N and deflection breaks at 3.734 mm. The time to failure is 22 seconds for the Figure 7. Force (N) against Deflection (mm) of 265g fine and coarse fire block of clay composites maximum Young Modulus of 212 N/mm2 (Table 5). Generally, the 275 g block of fire clays composites requires the maximum break force and has the maximum Young Mod- ulus relatives to blocks 255 g and 265 g of clays composites under study. The 275 g block of fire clay composites will be better for furnace lining application than the 255 g and 265 g blocks. Figures 6, 7 and 8 shows the plots of Force (N) against De- 30 Saheed et al. / J. Nig. Soc. Phys. Sci. 4 (2022) 27–33 31 Table 2. Estimated grain sizes and mineral constituents of coarse Clay Peak no 2theta (rad) FWHM Grain Size (nm) Constituents 1 12.501 0.025 338.0839019 Interstratified illite- Smectile 2 17.45 0.037 229.7356597 Gypsum 3 19.86 0.128 66.63776651 Kaolinite 4 20.941 0.136 62.82444633 Jarosite 5 21.165 0.164 52.11724848 Jarosite 6 21.464 0.0172 497.1759627 Jarosite 7 23.622 0.141 60.87648083 Kaolinite 8 24.901 0.137 62.8043888 Kaolinite 9 24.02 0.12 71.58228586 Quartz 10 26.242 0.113 76.34585664 Kaolinite 11 28.501 0.026 333.40756 Kaolinite 12 34.45 0.038 231.4836125 Microcline 13 35.86 0.124 71.21558276 Pyrite 14 36.941 0.133 66.60274151 Kaolinite 15 37.165 0.162 54.71585907 Pyrite 16 38.464 0.017 523.4384171 Kaolinite plus Interstratified illite- Smectile 17 39.529 0.022 405.8083969 Kaolinite 18 40.43 0.033 271.3138386 Quartz 19 41.821 0.122 73.72312076 Kaolinite 20 42.937 0.134 67.37494247 Quartz plus kaolinite 21 45.178 0.161 56.52152987 Quartz 22 48.426 0. 170 54.14907336 Quartz 23 50.643 0.144 64.5478197 Quartz plus kaolinite 24 51.936 0.13 71.88749106 Quartz 25 55.04 0.134 70.70014627 Kaolinite 26 56.228 0.12 79.38153044 Quartz 27 60.52 0.022 442.1458637 Interstratified illite- Smectile 28 62.439 0.03 327.4856536 Kaolinite Table 3. Compressibility Analysis of 255g Block of Clay Test No Def. @ Break (mm) Def. @ L.O.P. (mm) Def. @ Peak (mm) Def. @ Yield (mm) Force @ Break (N) Force @ L.O.P. (N) Force @ Peak (N) 1 4.343 2.087 4.186 2.303 2631.700 2911.200 9924.000 Test No Force @ Yield (N) Strain @ Break (%) Strain @ L.O.P. (%) Strain @ Peak (%) Strain @ Yield (%) Stress @ Break (N/mm2) Stress @ L.O.P. (N/mm2) 1 3469.000 7.896 3.795 7.611 4.187 2.056 2.274 Test No Stress @ Peak (N/mm2) Stress @ Yield (N/mm2) Time to Failure (Secs) Time to Peak (Secs) Youngs Modulus (N/mm2) Tangential Modulus @ 0.000 N/mm2 (N/mm2) Secant Modu- lus 0.000 to 0.000 N/mm2 (N/mm2) 1 7.753 2.710 26.133 25.187 174.476 4.727 flection (mm) for the 255 g, 265 g and 275 g fire blocks of clay composites respectively. Figure 9 compares the behaviours of the three fire blocks together. The plot reveals the maximum load of the fire blocks at respective deflection (mm). Our inter- est in these plots is to investigate and compares the maximum load fire block clays composites can withstand. The 275 g block has the maximum compressive strength and Young Modulus of 7652 N and 212 N/mm2 respectively making it better than the 255 g and 265 g blocks for furnace lining application. 31 Saheed et al. / J. Nig. Soc. Phys. Sci. 4 (2022) 27–33 32 Table 4. Compressibility Analysis of 265 g Block of Clay Test No Def. @ Break (mm) Def. @ L.O.P. (mm) Def. @ Peak (mm) Def. @ Yield (mm) Force @ Break (N) Force @ L.O.P. (N) Force @ Peak (N) 1 4.671 2.164 3.628 2.273 1438.900 847.400 3851.000 Test No Force @ Yield (N) Strain @ Break (%) Strain @ L.O.P. (%) Strain @ Peak (%) Strain @ Yield (%) Stress @ Break (N/mm2) Stress @ L.O.P. (N/mm2) 1 1038.600 8.493 3.935 6.596 4.133 1.022 0.602 Test No Stress @ Peak (N/mm2) Stress @ Yield (N/mm2) Time to Failure (Secs) Time to Peak (Secs) Youngs Modulus (N/mm2) Tangential Modulus @ 0.000 N/mm2 (N/mm2) Secant Modulus 0.000 to 0.000 N/mm2 (N/mm2) 1 2.735 0.738 28.100 21.845 93.892 21.094 Table 5. Compressibility Analysis of 275 g Block of Clay Test No Def. @ Break (mm) Def. @ L.O.P. (mm) Def. @ Peak (mm) Def. @ Yield (mm) Force @ Break (N) Force @ L.O.P. (N) Force @ Peak (N) 1 3.734 2.349 3.132 3.132 7652.000 2964.300 9658.000 Test No Force @ Yield (N) Strain @ Break (%) Strain @ L.O.P. (%) Strain @ Peak (%) Strain @ Yield (%) Stress @ Break (N/mm2) Stress @ L.O.P. (N/mm2) 1 9658.000 6.789 4.271 5.695 5.695 4.270 1.654 Test No Stress @ Peak (N/mm2) Stress @ Yield (N/mm2) Time to Failure (Secs) Time to Peak (Secs) Youngs Modulus (N/mm2) Tangential Modulus @ 0.000 N/mm2 (N/mm2) Secant Modulus 0.000 to 0.000 N/mm2 (N/mm2) 1 5.390 5.390 22.443 18.842 212.102 6.752 Figure 8. Force (N) against Deflection (mm) of: 275g fine and coarse fire block of clay composites Figure 9. Force (N) against Deflection (mm) of different fabricated fine and coarse fire blocks of clay composites 32 Saheed et al. / J. Nig. Soc. Phys. Sci. 4 (2022) 27–33 33 4. Conclusion In this research work, Okelele fine and coarse clays have been characterized to establish their potentials for furnace lin- ing application. The maximum compressive strength and Young Modulus as demonstrated by 275 g block clay are 7652 N and 212 N/mm2 at firing temperature of 1200 oC. The results of compressive strength analysis, mineral phase’s identification and ability to withstand higher firing temperature of 1200 oC proved that, Okelele fine and coarse fire block of clays meet the needed criteria for use as refractory raw materials. References [1] J. B. Mokwa, S. A. Lawal, M. S. Abolarin & K. C. Bala,“Characterization And Evaluation Of Selected Kaolin Clay Deposits In Nigeria For Furnace Lining Application”, Nigerian Journal of Technology (NIJOTECH), 38 (2019) 936. [2] J. A. Amkpa; A. E. Aye & F. E. Omagu, “Mechanical and Physicochem- ical Evaluation of Alkaleri Fireclay for Refractory Application”, Traek- toriâ Nauki = Path of Science 3 (2017). [3] A. M. Yami; M. A. B. Hassan & S. Umaru, “Evaluation of the Refrac- tory Characteristics of Dukku Clay Deposit”, Continental J. Engineering Sciences 2 (2007) 15. [4] P. U. Ochieze, & D. E. Esezobor, “Performance Evaluation of Refractory Bricks Produced from Nigerian Fireclays Blended with Zircon”, Global Journal of Researches in Engineering: J. General Engineering 18 (2018) 1. [5] P. O. Aiyedun, O. S. Olokode, S. O. Fakolujo, & B. U. Anyanwu, “An Evaluation of Strength Characteristics of Osiele Clay”, The Pacific Jour- nal of Science and Technology, 13 (2012). [6] Z. Elakhame, S. A. Bello, J. O. Agunsoye, I. Patric & O. Otitoju, “Char- acterization of Ujogba Clay Deposits in Edo State, Nigeria for Refractory Applications, Journal of Science”, Engineering and Technology, Kath- mandu University (2016) 12 71. [7] A. B. Etukudoh; K. G. Akpomie & O. C. B. Okereke, “Characterization of Ezzodo clay deposit for its industrial potentials”, International Journal of Advanced Engineering Research and Technology (IJAERT) 4 (2016) 1. [8] S. P. Malu, J. T. Ugye & R. B. Donatus, “Characterization of Clay for In- dustrial Application By Physicochemical, Xrf, And Tga Methods”, FUW Trends in Science & Technology Journal 3 (2018) 314. [9] E. E. Nnuka & J. O. Adekwu, “Refractory Characteristics of Kwa Clay Deposit in Plateau State”, N.S.E, Technical Transaction 32 (1998) 54. [10] O. Ombaka, “Characterization and classification of clay minerals for po- tential applications in Rugi Ward, Kenya”, African Journal of Environ- mental Science and Technology 10 (2016) 415. [11] J. O. Osarenmwinda, “Fabrication and performance evaluation of oil– fired crucible furnace using locally sourced materials”, Int. Journal of Engineering Research and Applications 5 (2015) 29. [12] I. F. Titiladunayo & O. P. Fapetu, “Selection of Appropriate Clay for Fur- nace Lining In a Pyrolysis Process”, Journal of Emerging Trends in En- gineering and Applied Sciences (JETEAS) 2 (2011) 938. [13] J. C. Ugwuoke & N.I. Amalu, “Characterization of Obe Clay Deposits for Refractory Production”, American Journal of Engineering Research (AJER) 6 (2017) 74. [14] A. B. Alabi; M. A. Salawu; R. A. Jimoh & T. Akomolafe, Appraisal of mechanical properties of different particle sizes of palm kernel shell, coconut shell and mixed palm kernel-coconut shells particles epoxy-filled composites, Sri Lankan Journal of Physics 21 (2020) 1. [15] O. J. Omowumi, Characterization of Some Nigerian Clays as Refractory Materials for Furnace Lining, Nigerian Journal of Engineering Manage- ment 2 (2000) 1. [16] E. E. Nnuka & Agbo J. E, Evaluation of the Refractory Characteristics of Otukpo Clay Deposit, N.S.E, Technical Transaction 35 (2000) 32. 33