Effect of guar gum on selective separation of sphalerite from galena by flotation

Adsorption, electrokinetic and notation studies have been carried out to investigate the interaction of guar gum with sphalerite and galena. The maximum density of adsorption of guar gum was obtained at pH 7.5 on sphalerite and at pH 11.5 on galena. The density of adsorption on galena was quite high compared with that on sphalerite. Both adsorption isotherms exhibited Langmuirian behaviour. The electrophoretic mobilities of galena and sphalerite became less negative with increasing concentrations of guar gum without any observable shift in the isoelectric point. The notation recovery of galena was reduced to about 20% by the use of guar gum at around pH 12, whereas sphalerite was only marginally depressed between pH 8 and 12, the findings complementing the results of the adsorption tests. Differential notation results at pH 12 indicate that sphalerite can be separated from galena with the use of guar gum as a depressant for galena. Dissolution experiments indicated a release of metal ions from sphalerite and galena and co-precipitation tests confirmed polymer-metal ion interaction in the bulk solution, which suggests that precipitation is the precursor to adsorption and consequent depression