METHOD FOR ASSESSING SURFACE QUALITY OF COPPER CATHODES

Abstract

In order to stabilize spiral elongation number at the required level (in accordance with the requirements of the European standard EN 12893 not less than 400 mm) the assessment of its distribution on the cathode sheet was carried out. The experimentally obtained results, processed using methods of mathematical statistics, showed significant discrepancies between the values of spiral elongation in the central and other parts of the cathode (upper, lower, side), which indicates an uneven distribution of the spiral elongation number along the cathode sheet. It was found that in order to form a representative analytical sample under cathode copper production of the Polar Division of MMC «Norilsk Nickel», the testing of cathodes should be performed using methods that include all areas of the cathode sheet, for example, cutting of a vertical strip from each cathode which has got in a representative sample, including edges and hanging ears. To determine the dependence of the spiral elongation number on the surface quality of copper cathodes, developed a special technique, based on the detection of the most frequently encountered defects in the surface of the cathode sheet, which assigned a certain numerical value in accordance with the ranking results. The proposed scoring system for the quality of cathodes in appearance allowed us to establish for the first time that stabilization of the spiral elongation number at a level of at least 400 mm is possible if the defectiveness of the cathode surface does not exceed 17 points per one electrolysis bath. The method has found practical application for preliminary quantitative estimation of the most widespread superficial defects of copper cathodes in the conditions of current production.