Moulding properties of Isasa River Sand bonded with Ipetumodu clay (Ife-North Local Government Area, Osun State, Nigeria) were investigated. American Foundry men Society (AFS) standard cylindrical specimens 50mm diameter and 50mm in height were prepared from various sand and clay ratios (between 18% and 32%) with 15% water content. The stress-strain curves were generated from a universal strength testing machine. A flow factor was calculated from the inclination of the falling slope beyond the maximum compressive strength. The result shows that the flowability of the samples increases from 18% to 26% clay content, its maximum value was attained at 26% and then it decreases from 30% to 32% clay content. The green compressive strength, dry compressive strength and air permeability values obtained from the mould samples were in accordance with standard values used in foundry practice. The x-ray diffraction test shows that the sand contains silicon oxide (SiO2), Aluminium oxide (Al2O3), and Aluminium silicate (Al6Si2O13). The mould samples were heated to a temperature of 1200 o C to determine the sintering temperature; fussion did not take place at this temperature. The results showed that the sand and clay mixture can be used to cast ferrous and non-ferrous alloys.
The authors established the chemical and phase compositions of grain fractions of the magnesia carbon scrap disintegrated using industrial cone crushers. The investigations included chemical and XRD analyses and optical investigations. The contents of admixtures: SiO2, CaO, Fe2O3 and Al2O3 increase with the decreasing size of the scrap grain fractions, whereas the C/S ratio decreases in finer and finer fractions due to changes of the phase composition. These relations are caused by the presence of low-fusible silicate phases, characterized by their cleavage and brittleness. Such phases were mainly derived from the graphite ash containing a high silica content. The scrap after removing its finest grain fractions can be recycled and utilized for producing the magnesia-carbon refractory materials. However, the finest grain fractions may be used, e.g. as a component of gunite mixes. Many years of experience collected by the ArcelorMittal Refractories Ltd., Krakow, Poland in the field of refractory scrap utilization has also been presented.