ABSTRACT
The leaching of monazite with sodium hydroxide has been attempted. Factors such as time of leaching, concentration of sodium hydroxide sclution and temperature were tested with the hope to optimize the leaching efficiency. XRF technique was used in the determination of concentration. In this work Egyptian monastic leached by alkaline treatment in reflux instead of the pyrometallurgical process using mechanochemical treatment where grinding is carried out in the presence of sodium hydroxide and followed by pressure leaching in autoclave that gives an incongruent result. It has been found that the monazite was effectively decomposed in 2hr at - 130°C using 600g/1 sodium hydroxide in the reflux. The recovery of thorium by this method and under these conditions is about 98.1%. A mathematical formula is also deduced which enables the calculation of thorium concentration in ppm obtained from the leaching in reflux system under different conditions with a good agreement with the experimental values and that obtained from the XRF technique