Influence of Sintering Temperatures on Physico-Mechanical Properties and Microstructure of Refractory Fireclay Bricks

Abstract

Abstract-ThisI. INTRODUCTION The up surge application and request for refractory bricks had motivated this research to investigate the raw clay materials used for production of refractory bricks. The raw clay materials were subjected to standard refractory fireclay brick tests requirement through the tests procedures for chemical, thermal, physical and mechanical properties [1]. Clay as a raw material varied considerably in terms of workability, structure, particle-size distribution, plasticity and mineralogical composition. These differences paved way for clays being categorized or classified into plastic clays, flint clays, kaolin clays, fireclays and ball clays [2]. In the refractory industries, they are grouped and referred to as illite, Montmorillonite and kaolinite [3]. Refractories are clay materials that are generally capable of enduring very high temperatures without deformation, structural changes or softening [4]. The type of refractories is determined by the type of refractory requirement for a specific purpose. The types are classified as acid, basic and neutral refractories [5]. Traditionally these clay materials containAl 2 O 3 .SiO 2 .H 2 O to produce alumino-silicates refractory fireclay bricks. They are further classified by temperature. When the temperature is between 1500-1700 0 C, it is branded as refractory e.g. fireclay.The temperaturebetween 1700-2000 0 Cis recognized as high refractory e.g. chromite. When thetemperature is 2000 0 C, it is referred to as super refractory e.g. zircon [5].The applications of refractories are employed in the construction of furnaceslinings, ladles, reactors, ovens and kiln [6]. This disposition proved that the raw clay material is a fireclay and belongs to the alumino-silicate subgroup. The uses for fireclay refractory brick comprise of porous refractory insulation behind furnace linings, refractory fireclay bricks and ladles [7].Refractories are frequently consumed basically in the iron and steel industries [8]. Contamination of refractories clays are usually with limited amount of impurity as contained in the oxides which are CaO, MgO, TiO 2 , Fe 2 O 3 , Mn, SO 3 , ZnO, Cl, K 2 O, P 2 O 5 , Cr 2 O 3 and alkali oxides that acts as fluxing mediator at very high temperature [9]. In the process ofiron and steel production, the use of basic oxygen furnace (BOF) for the molten iron that comes from the blast furnace is decontaminated from the scums.Refractories belonging to silica-alumina have heterogeneous microstructure with bulky grain size and reasonable rate of porosity [10]. In Nigeria, previous investigation work has been done on the characterization of the native refractory raw clay materials for the making of quality refractory fireclay bricks for furnace lining, ladles, ovens and kilns [11]. In many cases, the outcome and results of such previous work were inconclusive and not comprehensive enough to be used or adopted for industrial uses. They were not subjected to standard test requirement for refractory bricks production.The researches for an alterna...

Mechanical and Physicochemical Evaluation of Alkaleri Fireclay for Refractory Application

“…It is essential to note that bulk density as a clay property is a major criterion in material selection for refractory production. The bulk density of Alkaleri fireclay fell within the standard values of 1.7-2.3 g/cm 3 for fireclay refractory brick [6,7,12].…”

“…The sintering temperature influenced the close up of the pore spaces and thereby increased strength of the fireclay brick. The Alkaleri clay apparent porosity fell within the standard value of 20-30 % porosity for fireclay refractory bricks [6,7,12]. Section "Technics" 6.18…”

“…In the chemical composition result as presented in Table 1 showed that the dominant oxides in the clay are SiO2 and Al2O3 with 2.56 % of impurities and can be categorized as alumino-silicate fireclay brick. The Alkaleri clay is in the range of chemical composition of 65-80 % SiO2 and 18-30 % Al2O3 which are classified as high duty (Siliceous) refractory fireclay brick [2,6,12]. The Gombe clay is suitable for production of furnace linings (Table 1).…”

“…The result showed a typical characteristic of clay when exposed to extreme thermal treatment like the sintering process. The low porosity of the refractory fireclay brick make it suitable for it use for production of furnace linings [12].…”

“…It is available in commercial quantity but they remained untapped and under-utilized in the country [11]. Nearly all the refractory bricks used in the metallurgical and ceramic manufacturing industry in Nigeria are imported [12].…”