CAPACITY OF CHROME IONS FIXATION BY BLAST FURNACE SLAG

Storage of industrial wastes in landfills often generates leachates with high heavy metal concentrations. Conventional solidification/stabilisation process using ordinary Portland cement shows a lack of mineralogical control on some elements, especially on Cr ions. Addition of blast furnace slag seems to allow fixation of Cr ions, in particular Cr₆₊. The aim of this study was to compare and especially quantify the effect of blast furnace slag and Type 1 ordinary Portland cement in the presence of solutions rich in Cr ions. Results show that the blast furnace slag exerts a solubility control on Cr and Mo concentrations and that there is no ionic competition between these two ions. Blast furnace slag completely fixes Cr₆₊ present at a concentration of 1000 ppm in a sample with a slag to solution ratio of 1:5. X-ray diffraction results on this sample reveal the presence of calcite, merwinite and two calcic chromium oxides (Ca(CrO₂)₂ and CaCrO₃). These oxides were not detected by scanning electron microscope analysis, which confirmed the presence of calcite and highlighted the presence of calcium silicate hydrates and hydrated calcium aluminate phases.

• INTRODUCTION

• MATERIALS

• METHODS

• RESULTS AND DISCUSSION

• CONCLUSION

• ACKNOWLEDGEMENTS

• REFERENCES