Determination of the uranium content of Egyptian phosphate ores by passive and active detectors

Uranium contents of phosphate ores and fertilizers collected from El-Sobaeya and El-Suez mines in Egypt were determined by measuring the radon emanated from these samples. In our method, neither direct contact of CR-39 track detectors to the samples nor thermal neutron activation process is required. The concentration of (222)Rn in the emanation container (Genitron Instruments GmbH) is dependent on the uranium deposited in the phosphate sample. The CR-39 and a pulse ionization chamber, Alpha GUARD PQ-2000 (Genitron Instruments GmbH) were simultaneously used for radon detection. The detection efficiency of CR-39 was calibrated with the Alpha GUARD. The uranium content determinations were performed using a high-resolution inductively coupled plasma mass spectrometer for comparison. The measurements revealed a very high uranium content, 355 ppm for ore and 118 ppm for fertilizer from El-Sobaeya mine, while it was 7 ppm for fertilizer from El-Suez. Although the uranium content of ores from El-Sobaeya mine is within permissible limit for the manufacturing of fertilizers, the phosphate ore from El-Suez is much safer for fertilizers. (C) 2003 Elsevier Ltd. All rights reserved.