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    Sampling of Copper Cathodes

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    In order to devise a system for the sampling of copper cathodes using a mechanical punch it was first necessary to establish the distribution of impurities between individual samples and their location. To do this a cathode was divided into 171 pieces and each piece melted individually. Samples for analysis were then taken from the melt by suction through a 3.8-mm-ID glass tube and analyzed for impurities by emission spectrometry. The results obtained were summarized and studied statistically to determine the average content and standard deviation.

    It was then essential to correlate this information with the results obtained when sampling plant production using a mechanical punch. For this purpose a total of 578 cathodes (60 tonnes) was sampled, a template was used to locate 30 sampling points across the diagonal of a cathode, and 5 buttons were taken from each cathode in such a way that all 30 sampling points were punched an equal number of times. The 5 buttons from each cathode were melted, sampled and analyzed in a similar manner to that used for the sampling of the individual cathode. These results were also studied statistically, and in combination with the first results an overall standard deviation was determined statistically under various combinations of number of cathodes selected, number of buttons from each sample cathode, and number of samples per final sample.

    From this work it has been determined that, at this particular plant, it is satisfactory when sampling a lot of approximately 60 tonnes to punch 5 buttons from each of 6 selected cathodes, to melt the 30 samples together, and to figure an arithmetic average of 3 analyses of the sample taken from the resultant melt.


    copper, cathodes, sampling, analysis, impurities, statistics, refinery, Spain

    Author Information:

    Lamela, M
    Chief Chemist and Metallurgical Manager, Río Tinto Minera, S.A., Huelva,

    Palacios, C
    Chief Chemist and Metallurgical Manager, Río Tinto Minera, S.A., Huelva,

    Committee/Subcommittee: B02.09

    DOI: 10.1520/STP32534S