During a study on the Fe-phosphide phase formed during phosphorus production in a submerged arc furnace, a sample of ferrophosphorus was found which contains a so far unknown uranium-bearing Fe-phosphide. Uranium, as well as other trace metals like Mn, V, Cr, Ni, Zr, originates from the apatite ore used. Ti originates partly from the silica and coke used in the reduction process, but mainly from the clay used to produce ore pellets. In this paper the ferrophosphorus is described with respect to composition and crystalline compounds present. The crystallization sequence is discussed with respect to the FeP-phase diagram. The main phases found in the ferrophosphorus are FeP and Fe_2P. With respect to trace and minor metals, it is observed that Si preferably enters the FeP-phase, whereas Ti, V, Cr, Mn and Ni preferably enter the Fe_2P-phase, which is an analogue of the mineral barringerite. This study gives some insight into the behavior of impurities during crystallization of an iron-rich Fe-phosphide melt. The uranium-bearing phase has an overall Me_2P-stoichiometry (Fe_(1.59), Ti_(0.06), V_(0.03), Cr_(0.02), Mn_(0.06), Ni_(0.02), U_(0.15), Zr_(0.09))_(2.02) (P_(0.96), Si_(0.02))_(0.98). An X-ray diffraction pattern of this phase is given for identification purposes.
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