A process for extraction of Si02 from waste coloured glasses by alkali fusion using NaOH was investigated. In this study, glass waste coloured bottles of green, blue, brown or black were selected as samples of waste glasses. These coloured bottles were qualitatively confirmed to contained elements of Na, Mg, Al, Si, K, Ca, Ti, Mn, Fe and Cu from energy dispersive x-ray spectroscopic analysis. The condition for alkali fusion of NaOH and the waste glasses was optimised, i.e. for each bottle, the composition was NaOH: crushed glass bottle=90:10 mass%, melting temperature was 500 deg C and melting time was 2 hours. For each waste coloured bottle, the sodium silicate solution was prepared by using the sodium silicate obtained by alkali fusion. After mixing HCl with the solution, Si(OH)4 was then precipitated by boiling the solution which became a very strong acid.
