Titrimetric determination of uranium in low-grade ores by the ferrous ion-phosphoric acid reduction method.

The modification and extension of the U.S.A.E.C. ferrous ion-phosphoric acid reduction method for the determination of uranium in high-grade or relatively pure material to a method for the determination of uranium with a high accuracy and precision, in ores containing 0.004-7% U is described. It is simple, rapid and requires no prior separations from elements that, in other methods, frequently interfere. For sample materials having very high concentrations of interfering elements, a prior concentration step using extraction with tri-n-octylphosphine oxide is described, but it is shown that, for most low-grade ores, this step is unnecessary.

Chelatometric determination of calcium and magnesium in iron ores, slags, anorthosite, limestone, copper-nickel-lead-zinc ores and divers materials.

Chelatometric methods for the determination of calcium and magnesium in iron ores, slags, anorthosite, copper-nickel-lead-zinc ores and various other materials are described. Potential interfering elements are masked with triethanolamine and potassium cyanide. In one aliquot calcium is titrated at pH > 12, with calcein and thymolphthalein mixed indicator and in another aliquot calcium and magnesium are titrated in ammonia buffer, with o-cresolphthalein complexone screened with Naphthol Green B as indicator. The results compare favourably with certified values for reference materials of diverse nature.

The differential pulse polarographic determination of trace amounts of tin and its application to zinc-aluminium alloys.

A differential pulse polarographic procedure for the determination of 0.001-0.02% of tin in zinc-aluminium alloys is described. The tin is first separated from interfering elements such as copper and lead by homogeneous co-precipitation with aluminium succinate. The tin is determined polarographically in a 1M hydrochloric acid + 4M ammonium chloride electrolyte. After the tin has been masked with alkaline citrate a second polarogram is recorded to ascertain whether residual lead is present and, if so, a correction is applied.

Determination of zinc in blast furnace flue dusts.

Two methods for the determination of zinc in blast-furnace flue dusts are described. One involves a solvent extraction step using methyl isobutyl ketone to separate the zinc from the bulk of the interfering elements, followed by a complexometric titration of the zinc with EDTA, using Eriochrome Black T as indicator. The other employs differential pulse polarography with a hydrochloric acid + pyridine supporting electrolyte. In this method, the interference of iron is prevented by reducing it with hydroxylamine hydrochloride; aluminium is complexed with potassium fluoride. Other elements, with the exception of cobalt, do not interfere. Excellent agreement between the two methods is obtained in the range 0.01-0.6% zinc.

Determination of polythionates and thiosulphate in mining effluents and mill circuit solutions.

A method is described for the determination of total polythionates plus thiosulphate by acidimetric titration. The titration can be carried out either at the Methyl Orange (pH = 4.30) or at the phenolphthalein (pH = 8.20) end-point, with standard sodium hydroxide solution, to determine the amount of acid produced on oxidation of the thiosulphate and polythionates. The precision and accuracy are good and samples containing as little as 0.1 mg of the thio salt can be analysed very easily. Results obtained by this method are compared with those obtained by a calorimetric method and are in good agreement.