Abstract

---

This study determined the clay content, chemical composition, grain fineness number, distribution and shape of some selected silica sand deposits in south west Nigeria. This is with a view to document the silica sand deposits in Nigeria for sand moulding in the foundry industry. The silica sand deposits were collected from four river bed de posits in Igbokoda (Ondo State), Ote (Ogun State), Opa (Osun State), and Osooro (Oyo State), respectively. The clay content off sand samples from these deposits were determined using washing off method; grain fineness num ber and distribution were evaluated using sieve analysis; grain shapes were observed using magnifying lens; chemi cal compositions were characterized by x-ray fluorescence; and the phases were characterized by x-ray diffractome ter. The results showed that the clay content for samples taken from Igbokoda, Ote, Opa, Osooro are 2.18%, 2.40%, 3.44%, 6.96% respectively. The average grain fineness number of 48.23, 53.74, 61.82, and 68.48 were obtained for samples taken from Igbokoda, Ote, Opa and Osooro respectively. All the silica sands from the study area have a mixture of angular and sub-angular grain shapes. X-ray diffraction and fluorescence result showed quartz as the most prominent mineral in the selected sand deposits with silica contents of 83.14%, 80.56%, 86.46% and 82.71% for Igbokoda, Ote, Opa, and Osooro respectively. From the outcome of this study, it was concluded that all the sili ca sand deposit in the study area are grade D.

Keywords: Silica Sand; Clay; Grain Fineness; Grain Shape; Quartz; X-Ray Diffraction