Selection of Flotation reagents for Separation of Pyrolusite from Calcite

The flotation behavior of pyrolusite and calcite was investigated using oleic acid as an anionic collector and dodecylamine as a cationic collector. The results showed that using oleic acid the maximum flotation recovery of pyrolusite occurs at pH=9 due to the chemisorptions of oleate ions, while in the cationic flotation the physisorption of dodecylamine results in a maxima at pH=8. It was found that in the anionic flotation, copper sulfate (CuSO4.5H2O) acts as pyrolusite activator and calcite depressant agent. The best results were obtained using 1000 g/t copper sulfate in the presence of 10-4 M oleic acid at pH=8. At these conditions the flotation recovery of pyrolusite and calcite are 83.6% and 38%, respectively. In the cationic flotation, sodium carbonate and calcium chloride depress the calcite flotation significantly. Using 10-4 M sodium carbonate without a significant decrease in pyrolusite floatability the calcite flotation recovery reduces to 13.7 % at a pH of 7.5. At this pH, the use of 5×10-4 M calcium chloride with a slight decrease in pyrolusite floatability decreases the calcite flotation recovery from 57.2% to 10.8%. Thus, the cationic flotation using sodium carbonate as a depressant agent for calcite is suggested for separation of pyrolusite from calcite.