The Low Grade Lead Ore Concentration Studies by Flotation and Gravity Methods

The low grade oxide-sulfide lead-zinc ore sample taken from Changarzeh mine located in south of Natanz city in Isfahan province، containing 2. 3% Pb and 1. 91% Zn was concentrated by flotation and gravity methods. Studies were concentrated on producing Lead concentrate with maximum recovery. So، the effects of different parameters such as type and amount of collector، milling retention time، amount of sodium sulfur and its preparation time، application of sodium silicate، pH and solid content were investigated in relation to the metal contents of concentrates and flotation efficiencies. Experiments in optimum condition was carried out with 200 g/t KAX as collector، 2000 g/t Na2S، 500 g/t sodium silicate and 30 g/t MIBC at pH 10. A rougher concentrate with a recovery of 94% was produced through this condition and a lead concentrate with 70% Pb was produced as a result of 3 cleaning stages of flotation with a recovery of 40%. The process of rougher flotation was also analyzed kinetically and 18 minutes was determined as the optimum flotation time. Application of gravity methods for producing commercial product or a middle product for flotation was considered with a special attention to the effect of table slope and amount of water and for jig the effect of water and frequency. The result of one stage gravity separation by shaking table was a concentrate with a grade of 46% and a recovery of 80%. As a result، shaking table can be proposed for production of preconcentrate to be used as feed of flotation process. But since jig can be used for separation of coarse particles and the lead content of Changarzeh mine is in the form of fine particles، the results of jig were not considerable.