V. G. Torgov

Extraction–atomic absorption spectrometric method for the determination of the platinum group elements and gold in copper–nickel ores using an autoclave sample decomposition technique

An ETAAS method was developed to determine the platinum group elements and gold in copper–nickel ores using a single sample. It is based on an approach involving interconnected consideration of the main components of analytical procedure (autoclave decomposition of sample; collective extractive preconcentration of metals with a mixture of alkylaniline hydrochloride and petroleum sulfides; and atomic absorption spectrometric analysis of the extract). The concentrations of elements determined in standard reference materials (lode and impregnation copper–nickel sulfide ores) were found to be in accordance with the certified values, within experimental error. The relative standard deviation varied between 2 and 17% at 0.05–10 mg kg–1 element concentrations. The determination limits were 0.001–0.06 mg kg–1 for a 5 g sample and an extract volume of 5 ml.

Determination of platinum-group metals and gold in the group extract by inductively coupled plasma atomic emission spectrometry after the autoclave decomposition of geological samples

An ICP AES procedure is developed for the direct determination of all platinum-group metals (PGM) and Au in an extract based on the correlation between the main constituents of the analytical cycle. Concentrations interfering with the determination PGM and Au in the extract admissible for ICP AES were found. It was shown that the extraction system (a mixture of p-alkylaniline with oil sulfides in o-xylene or in post-xylene fractions) is compatible with ICP, ensures the 10- to 20-fold preconcentration of PGM and Au and the necessary depth of extract purification (106) of the interfering elements. The accuracy of the procedure is confirmed by results of analyses of seven certified reference samples (GSO) and the agreement with the results of the reference ETA AAS determination. The procedure was tested on raw materials and products of a copper-nickel plant for the determination of all PGM, including osmium and Au in the concentration range 10−7 to 10−4%.

Concentration of Platinum(IV) From Acidic Chloride andSulfate–Chloride Aqueous Media With Reversed Micellar Solutions ofOxyethylated Surfactant

The possibility of employing reversed micelles of oxyethylated surfactants to concentrate platinum from acidic aqueous media was investigated. A procedure for reversed micellar concentration is described. Platinum concentration was effected by means of desolubilization in a non-traditional back-extraction stage by dilution of the reversed micellar solution with chloroform or a mixture of chloroform with hexane. In acidic sulfate–chloride media the distribution ratio of Pt IV increased to about 10 2 –5 × 10 3 in the presence of Br - and I - as complexing agents. In chloride media the distribution ratio could be increased to about 2 × 10 3 by using SnCl 2 . The maximum recovery of platinum from the extract did not exceed 85%. With I - as a complexing agent, no back-extraction could be performed. With this back-extraction procedure, the Pt IV concentration factor varied from about 10 2 to 10 3 depending on the aqueous feed composition. It was shown spectrophotometrically that Pt IV complex species were the same in the feed, extract and desolubilized aqueous solution. The possibility of the spectrophotometric determination of platinum with SnCl 2 directly in the reversed micellar solution is demonstrated.

Extraction-back extraction preconcentration in the system based on p-alkylaniline and oil sulfides for determining platinum-group metals and gold by inductively coupled plasma atomic emission spectrometry

A procedure is developed for determining all platinum-group metals (PGM) and gold (10−7 to 10−4%). It includes the autoclave digestion of samples with the transfer of metals into a hydrochloric acid medium without losing osmium and ruthenium, group 10- to 20-fold extraction preconcentration of precious metals with the removal of matrix interfering elements to a factor of 105–106, and the analysis of the group back extract of PGM and gold by ICP AES. A method is proposed for the quantitative back extraction of all PGM and gold from a group extract in two steps of consecutively washing the extract with ammonia solutions and thiourea. The procedure is tested on seven GSO samples and technological objects. It is shown that ICP MS can be used for the analysis of group back extracts of PGM and gold.