Adsorption, electrokinetic and differential flotation studies on sphalerite and galena using dextrin

Adsorption, electrokinetic and flotation studies have been carried out to i nvestigate the interaction of dextrin with sphalerite and galena, The adsor ption density of dextrin onto sphalerite increases with increase of pH up t o pH 7.5, and thereafter decreases, while that onto galena shows a maximum around pH 11.5, It is observed that the adsorption density of dextrin onto galena is quite high compared to that on sphalerite, Both the adsorption is otherms exhibit Langmuirian behaviour. Electrokinetic measurements reveal t hat the isoelectric paints of sphalerite and galena are located around pH 3 . The electrophoretic mobilities of both the minerals become less negative following polymer adsorption without any apparent shift in the isoelectric points. Dissolution experiments indicate release of metal ions from sphaler ite and galena, while, co-precipitation tests confirm polymer-metal ion int eraction in the bulk solution. Flotation tests show that dextrin effectivel y depresses galena in the pH range of 10 to 12 but not sphalerite, compleme nting the adsorption results. Differential flotation results indicate that sphalerite can be separated from its synthetic mixture with galena using de xtrin as a depressant for galena at pH 12.1. Possible mechanisms of interac tion between the two sulphide minerals tested and dextrin are discussed. (C ) 1999 Elsevier Science B.V. All rights reserved.