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.
References
European Standard EN 1978:1998. Copper and copper alloys – copper cathodes. Introdused: 1998-08-15. Brus-sels: Copyright European Committee for Standardization. 2005.
GOST 859-2014. Med. Marki. (State Standard 859-2014. Copper. Grades). Introdused: 2015-07-01. Moscow: Standardinform. 2015.
GOST 546-2001. Katody mednyye. Tekhnicheskiye usloviya. (State Standard 546-2001. Copper cathodes. Specifications). Intro-dused: 2002-03-01. Moscow: Standardinform. 2007.
Levin A.I. Electrochemistry of non-ferrous metals. M.: Metallurgiya. 1982. 255 p. (in Russian).
Ostanin N.I., Rudoy V.M., Zaykov Y.P., Demin I.P., Shuklin M.A., Koryakin V.M. Investigation of mechanisms for reducing the content of impurities in the cathode deposit of copper. Abstracts of 7th Int. Conf. Coatings and surface treatment. M.: RKHTU im. D.I. Mendeleyeva. 2010. Р. 65-66 (in Russian).
Mubarok Z. Dendritic cathode growth during copper electrorefining in the presence of solid particles. Erzmetall. 2005. V. 58. N 6. Р. 315.
Solid State Chemistry. Ed. by A.V. Knotko, I.A. Presnyakov, Y.D. Tretyakov. M.: Izd. tsentr «Akademiya». 2006. 304 p. (in Russian).
Vikarchuk A.A., Volenko A.P., Tyurkov M.N., Dov-zhenko O.A. Variety of growth forms of pentagonal crys-tals during electrocrystallization of copper. Vestn. Samar. Gos. Tekhn. Un-ta. 2004. N 27. P. 111-114 (in Russian).
Akhmedshina V.A., Bazotov V.Ya. Crystallization of energy-saturated compounds from solutions. Kazan: Izd-vo KNITU. 2012. 124 p. (in Russian).
Portnov V.N. Effect of impurities on the rate of growth of crystal faces from solution. N.Novgorod: Izd-vo Nizhegorodskogo gosuniversiteta im. N.I. Loba-chevskogo. 2013. 166 p. (in Russian).
European Standard EN 12893-2000. Copper and copper alloys – copper cathodes. Introdused: 2000-03-22. Brus-sels: Copyright European Committee for Standardization. 2000.
Leuprecht G. Spiral elongation number and AR-value of copper rod incorrelation to cathode quality. ISA process users´ conference. Hitachi (Japan). 2004.
Lapshin D.A., Salimzhanova Е.V., Shulga Е.V., Ulya-nova Е.V. Estimation of heterogeneity of impurity distri-bution and spiral elongation index (SEN) over copper cathode area. Abstracts collection of IV All Russian Conf. on Chem. Technology. M.: 2012. Р. 248 (in Rus-sian).
GOST 28515-97. Med. Metod ispytaniya prob na ud-lineniye spirali. (State Standard 28515-97. Copper. Metod of test for sample shiral elongation). Introdused: 1998-07-01. M.: Standardinform. 2005.
GOST Р50779.11-2000 (ISO 3534.2-93). Statisticheskiye metody. Statisticheskoye upravleniye kachestvom. Terminy i opredeleniya. (State Standard Р50779.11-2000. Statistical methods. Statistical quality management. Terms and Definitions). Introdused: 2001-07-01. M.: Standard-inform. 2008.
Sidenko A.V., Popov G.Y., Matveeva V.M. Statistics. M.: Izd-vo «Delo i servis». 2000. 464 p. (in Russian).
Rubleva G.V. Mathematical statistics: statistical criteria for testing hypotheses. Tyumen: Izd-vo Tyumenskogo Gos.Un-ta. 2014. 50 р. (in Russian).
Tarasova O.B., Shaykina Е.V., Shibalkin A.Е., Kagirova M.V. Mathematical statistics. Ed. by O.B. Tarasova. M.: Izd-vo RGAU-MSKHA im. K.A. Timiryazeva. 2014. 136 р. (in Russian).
Kozlov S.L., Yudin E.V., Yuriev A.I., Salimzhanova E.V., Shulga Е.V. Improvement of physicomechanical characteristics of cathode copper. Tsvetnye Metally. 2013. N 6. P. 73-78 (in Russian).
Kozlov S.L., Dylko G.N., Salimzhanova E.V., Yuriev A.I., Shulga Е.V. Improvement of physical and mechani-cal characteristics of cathodic copper in the Polar Divi-sion of MMC Norilsk Nickel to meet the requirements of the London Metal Exchange. Sat. doc. V Int. congress. Non-ferrous metals. Krasnoyarsk. 2013. P. 192-195 (in Russian).
