Abstract
The nickel refining company "Norilsk Nickel Harjavalta Oy" (NNH) produces three main types of nickel products: cathode nickel, nickel powders (briquettes), nickel salts. The decisive role in achieving high performance and guaranteed quality the nature of the impurities distribution and their behavior control, in particular selenium, plays a role in nickel products. Selenium has a sharply negative effect on the process of obtaining a cathode nickel base. At elevated concentrations in nickel-cobalt solution, this impurity makes it impossible to stable obtain commercial nickel cathodes. The study of the selenium behavior patterns in the processing circuit of metallurgical intermediates, such as feinstein and stein of electric slag-cleaning furnace (ESCF), made it possible to make the necessary changes to the technological scheme of the NNH leaching shop and to clarify the operating parameters of the main operations. A hypothesis is proposed about the possible mechanism of the effect of metallized fraction (alloy) contained in the feedstock on the process of reducing Se6+ to Se4+. The experiments performed confirmed the direct dependence of the selenium deposition degree from the solution to the solid precipitate from the alloy content in the feedstock. It has been established that by combining the applied ESCF matte with feinstein and/or nickel concentrate (NC) from feinstein separation, it is possible to effectively control the distribution of selenium in NNH technology, preventing its critical concentrations in nickel catholyte. Based on the research results, a two-flow scheme for processing processed products has been implemented, in which it is envisaged to use a combination of NC and products with a high content of metallized fraction. This method allowed to minimize the concentration of selenium in nickel catholyte.
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