Stabilization of copper sludge by high-temperature CuFe2O4 synthesis process

Copper sludge was stabilized by high-temperature CuFe2O4 ferritization technique with different sintering temperature, isothermal time and Fe3+/M2+ molar ratio. Copper is stabilized by inserting the copper ion into the stable CuFe2O4 structure by ferritization. The result indicates that sintering temperature above 800 °C would be proper temperature range for CuFe2O4 synthesis. When the Fe3+/M2+ molar ratio of sludges are above the stoichiometric ratio of 2, copper ion in sludge would be stabilized and hence be kept from leaching out. From the result of relative XRD intensity ratio, the equilibrium of the ferritization reaction could be reached by prolonging the isothermal time to 10 h. Judging by the TCLP results, the optimum ferritization parameters are Fe3+/M2+ molar ratio equal to 3.5, sintering temperature at 800 °C and isothermal time above 10 h.