Comprehensive utilization of spent magnesia-chrome refractories with gravity separation followed by flotation

This study investigated the comprehensive utilization of spent magnesia-chrome refractories through gravity separation followed by flotation. The characteristics of refractories, the effects of various process parameters on the recovery of valuable metals and the adsorption mechanism of xanthate on silver were examined comprehensively. The results revealed that the metals penetrated into the refractories from cracks and holes. The penetrated metal particles were composed of different metal elements, several of which were dissolved in refractories. The optimum parameters were derived as follows: 60% particles passing a grinding fineness of 0.074 mm for gravity separation and regrinding tailing to 80% particles passing 0.074 mm for flotation, pH 8, 500 g/t of combined collector and 200 g/t of emulsified kerosene. Under these conditions, 99% Ag, 82% Pb and 81% Bi were recovered by a closed-circuit test. The obtained concentrates can be smelt as feeding, whereas the tailings with low impurities can be used as raw material for new refractories. The electrochemical and Fourier transform infrared measurements indicated that double xanthate and silver butyl xanthate were generated on the silver surface, which could improve the floatability of metals.