ALTERNATIVE OF OBTAINING TEST BARS OF BULLION FROM DUPLICATE SAMPLES
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Abstract
To fulfill the request of one of the gold producing plants of the country related to the need to perform a better characterization of its final product (gold bullion), a few test bars were obtained with the following specific contents: Au 10-75%, Ag 4-50%, Cu 3-55%, Pb 3-25% and Zn 0.01-0.25%. To this purpose, the control samples to be used for the preparation of the test bars were selected, and the bars were obtained by casting those samples. In order to carry out this work, it was necessary to construct appropriate molds for the casting of the molten material, which required the design of templates, the development of volume calculation models, the selection of the most appropriate materials (in this case, stainless steel plates). The molds constructed in correspondence with predetermined volumes, were used to pour of molten material at a temperature of 1070º centigrade in a melting furnace, finally getting 7 small test bars, that were polished and drilled according to NC1071: 2015 Gold bullion-Sampling for the subsequent characterization of the material. The evaluation of the gold and silver contents was obtained by the application of the Cuban Standard NC 1069: 2015 Gold bullion ─ Determination of gold and silver by cupellation (Fire assay), while the rest of the accompanying elements were determined by the procedure DCM-PT-05-005: Determination of Au, Ag, Al, Be, Cu, Ni, Pb and Zn in Au / Ag alloys using the Optical Emission Spectroscopy with Inductively Coupled Plasma (ICP-OES), corresponding the results obtained with the expectations of the production plant.
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