EVALUATION OF QUARTZ DEPOSIT IN ANGWAN DOKA, KOKONA NASARAWA STATE-NIGERIA FOR PRODUCTION OF DENSE REFRACTORY BRICKS

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Department of Environmental Design

ABSTRACT
Samples of quartz were sourced from deposit site at AngwanDokaKokonaNasarawa State Nigeria. The samples were beneficiated and crushed to smaller particle sizes ranging from fine, medium to coarse. The samples were prepared by the semi-dry method, with moulding pressure of 300 kN to form brick. After drying at 110oC, the bricks were burnt at 1450oC. The refractory bricks turned brownish in colour with some spot-dot tint colour on their surfaces; the refractory bricks were investigated to determine their chemical and physical properties. X-ray fluorescence analysis result showed SiO2 to be the major oxide at 96.25%. Other oxides present in the quartz sample as impurities were MgO-0.88%, Fe2O3-0.51%, Cr2O3-0.18%, CaO-0.02%, etc. Al2O3 and TiO2 were not detected, loss on ignition (LOI) was 2.037% and the total sum of impurity contents of 1.713% falls within the tolerable impurities associated to silicates group of refractories. The refractory bricks have an average linear firing expansion value of 2.9% and it is in accordance with (ASTM C179-14 (2014). The apparent porosity value of the brick was 33.1% which is below recommended ASTM value of (17-25%). The bulk density was 1.7 g/cm3; cold crushing strength was 202.56 kg/cm2. Thermal shock resistance showed that 9 heat cycles were required at 900oCbefore destruction. Therefore, it was categorized as having a good thermal shock resistance; this is due to the fact that the 9 heat cycles falls within recommended ranges of 7-12 cycles for silica dense refractory brick. The quartz from AngwanDokaKokonaNasarawa State formed a silica dense refractory brick which is among the medium heat duty group of silicate refractories. The produced refractory bricks can be used in applications such as construction of reheating furnace roofs, regenerator chambers, furnace doors etc. where moderate strength and heat treatments were required.