Abstract
Recent investigation has revealed that a trace of bismuth has an important effect on the nodulizing of graphite in the manufacturing of nodular graphite cast iron, and this makes it necessary to determine an extremely small amount of bismuth in pig iron and cast iron overlooked heretofore.
One g. sample is dissolved in perchloric acidnitric acid mixture and heated to white fuming. The residue is taken up in hydrochloric acid to 68N HCl and the majority of iron is removed by MIBK extraction. After the insoluble material including silica is separated by filtration, the residual iron is extracted with MIBK. The HCl layer is evaporated to dryness and the residue is dissolved in 30ml 0.3N HCl. The solution is transferred into a separatory funnel and the bismuth is adsorbed on 20ml of xylene solution of 10% Amberlite LA-1. The bismuth is liberated with 3N HNO3, concentrated to 1ml and heated with 1ml perchloric acid
The perchloric acid is driven off, 5ml of a supporting reagent (1N HCl+N/500 HCl) is added, and the polarogram on 00.25V (vs. Hg pool) is taken. Bismuth is determined by the aid of a calibration curve preliminarily prepared. 0.0020.0025% bismuth was estimated by the proposed. method.
