EGYPTIAN MONAZITE DIGESTION BY SULPHURIC ACID PROCESS; SEPARATION OF THORIUM

摘要

The major factors that affect the digestion the monazite mineral obtained from the Egyptian black sand deposits on Rosetta area and the along Mediterranean coast using sulfuric acid were investigated experimentally. The results reveal that digestion temperature of 220°C, acid/monazite ratio of 1.6/1, digestion time of 2.5 hrs and acid concentration of 93% verifies the maximum digestion efficiency for the studied monazite sand, which reached to 93.7%. Precipitation of thorium, rare earths and uranium from the filtrate sulfate solution was carried out using ammonium hydroxide, as a neutralizing agent. The precipitation efficiency of thorium at pH 1.1 was 99.1 % With only 1% of the rare earths co-precipitated. Further precipitation of uranium at pH of 6.5 verifies almost complete precipitation.