Document Type : Original Article
Authors
1
Nuclear Materials Authority,Cairo, Egypt
2
Botany Department, Faculty of Science, Ain Shams University, Cairo, Egypt
3
Microbiology Department, Faculty of Science, Ain Shams University, Cairo, Egypt
Abstract
Four phosphate rock samples representing different phosphate mineralization modes in Egypt were
selected from Abu Tartur, Nile valley and Red sea areas. Factors affecting the phosphate rock solubilization
and some of the contained valuable elements by Aspergillus niger, Penicillium sp. and Pseudomonas
fluorescence, were studied with especial orientation towards the completion of phosphate rock samples
solubilization especially the low grade one. Effect of nitrogen source type on leaching efficiency by
Aspergillus niger when two nitrogen sources on the phosphate bioleaching efficiency, it is clear that
the ammonium chloride is more favorable as nitrogen source than sodium nitrate in the bioleaching of
phosphate rocks.When Aspergillus niger was applied under the following conditions: 50 g/l of sucrose as
a carbon source, 0.1 N of ammonium chloride as a nitrogen source, 10 days incubation period, 0.5% solid:
liquid ratio for P2O5 and 5% for U and REE and - 270 mesh of grain size. The optimum leaching of P2O5,
U and REE from phosphate rock samples reached (23.27%, 17.4%, 11.4%, respectively), while at -60 mesh
they reached to 16.58%, 28.9%, 30.2% respectively. The optimum conditions for the maximal leaching
efficiencies of P2O5, U and REE when applying the Penicillium sp. from the phosphate rock samples were:
100 g/l of sucrose as a carbon source for P2O5 and U and 10 g/l for REE, 7,15 and 10 days incubation
period for P2O5, U and REE, respectively, 0.5% solid: liquid ratio for P2O5 and 5% for U and REE. Finally,
the application of phosphate rock samples grinded to -270 mesh of grain size for P2O5 and (-60 to -140)
for U and REE. The studied leaching efficiency of P2O5, U and REE gave at -270 mesh 33.66%, 24.3%,
15.9% respectively, while at -60 mesh they gave 33.76%, 26.7%, 17.8% and at -140 mesh gave 31.32%,
27.9%, 17.6%, respectively.The optimum conditions for the P2O5 leaching efficiency when applying the
Pseudomonas fluorescence were: 10 g/l of beef extract, 10 days incubation period, 0.5% solid: liquid ratio
and -270 mesh of grain size reaching 79.35%. The same behavior was traced for both U and REE leaching
efficiencies thus they reached 57.4% and 37.6%, respectively. While the attained results showed that the
non sterilized rock is more favorable and the addition of phosphate rock after the incubation of organism for
4 days gave the higher efficiency than the addition of rock at the beginning of experiment.
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