The determination of alumina in iron ores, slags and refractory materials by atomic-absorption spectroscopy

Abstract

As chemical methods of determining alumina are time-consuming, the simpler, more rapid atomic-absorption technique was adapted to iron ores, slags and refractory materials.

The basic technique comprises fusion of the sample with a sodium tetraborate-sodium carbonate mixture, extraction with dilute nitric acid, appropriate dilution and spraying under recommended conditions for aluminium. As the flux materials enhance the aluminium absorption, sample and corresponding calibration solutions should contain equivalent amounts.

Interference tests on synthetic solutions of the other constituents showed that the inhibiting effect of silica was suppressed by lanthanum chloride. A standard addition of lanthanum chloride was therefore incorporated and calibration conditions were developed to cover the ranges 0 to 1 per cent., 0 to 5 per cent., 0 to 10 per cent. and 10 to 35 per cent. of aluminium.

Applications to miscellaneous B.C.S. materials showed good agreement with accepted values and reproducibilities of ±0·035 per cent., ±0·12 per cent., ±0·18 per cent. and ±0·38 per cent. of aluminium, respectively, at the above levels.