Determination of phosphorous in titanium bearing minerals by potentiometric titration using Pb-ion selective electrode

A method for phosphorous determination in titanium bearing minerals by potentiometric titration using a Pb-ion selective electrode has been developed. Sample decomposition is achieved by means of K2CO3 fusion in a platinum crucible at 800°C for 30 min in a muffle furnace, and subsequent leaching with water of the fused melt. The aqueous leachate is neutralised with HClO4 and subsequent boiling. The obtained solution is used for titration with Pb(ClO4)2, and the Pb-ion selective electrode detects the end point. The lowest concentration determinable is 0.02% P2O5 in a solid sample. The method was applied on in-house titanium bearing mineral samples and on IGS-31 ilmenite sample (British Geological Survey, UK). Synthetic samples were prepared and analysed, and phosphorous recovery is in the range 98–106%. The recovery and accuracy of the present method have been validated by spiking experiments and by comparing with the spectrophotometric values, respectively. The precision of the proposed method in terms of relative standard deviation is 2.0%.