Effects of alumina cement on the refractory properties of leached Ipetumodu clay

The effect of alumina cement (Fe ₂O ₃) on the refractory properties of leached Ipetumodu clay has been studied. The raw clay was analysed using Scanning Electron Microscope (XL 30 ESEM/EDX), X-Ray Diffraction Machine (Philips PW 3710 with PW 1752 graphite monocromator) and X-Ray Fluorescence Machine (ARL 8410) in order to determine the purity level. The tests revealed an average of 5.7% Fe ₂O ₃ in the clay. The clay was then purified hydrometallurgical using different concentrations of oxalic acid (0.4, 0.8, 1.2, 1.6 and 2.0 mol/dm ³) and combination of different times (30, 60, 90, 120 and 150 min), temperatures (30, 50, 70 and 90°C) and agitation speeds (120, 160, 200 and 240 rev/min). The purification process as revealed by Atomic Absorption Spectrophotometry showed that Fe ₂O ₃ was reduced to 0.96%. Samples of leached clay containing different quantities of alumina cement, silica sand and sawdust were prepared, dried at 110°C for 24 hours and fired at 900, 1100, 1300 and 1500 ^oC at rate of 4°C /min, soaked for 2 hrs. These samples were presented for refractory tests (permanent linear change, refractoriness under load, thermal shock resistance, modulus of rupture, bulk density, cold crushing strength and apparent porosity). For all the properties tested, 3% sawdust, 20% silica sand and 10% alumina addition gave the optimum result with reliable phase integrity, as revealed by scanning electron microscopy.