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Nickel extraction from a nickel‐tungsten spent catalyst using column leaching
Author(s) -
Kelebek S.,
Distin P. A.
Publication year - 1989
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.280440407
Subject(s) - nickel , leaching (pedology) , catalysis , nitric acid , tungsten , chemistry , calcination , nuclear chemistry , materials science , metallurgy , inorganic chemistry , environmental science , soil science , soil water , biochemistry
Nickel extraction from an uncrushed spent nickel‐tungsten catalyst was studied using sulphuric acid leaching in a column. The effects of flowrate, temperature and acid concentration on the cumulative nickel recovery was investigated using a three‐variable, two‐level factorial design. Statistical analysis indicated that among these variables only acid concentration was significant (at the 95% confidence level) in the ranges investigated. The catalyst can be leached either by a two‐step process or in a single step following catalyst preoxidation. In either case extractions exceeding 95% can be obtained. With oxidized samples, single‐step acid leaching at 82°C yielded significantly better nickel extraction than at 95°C. This was attributed mainly to tungstic acid precipitation in the catalyst pellets, an effect which occurs rapidly at 95°C and retards the leaching of nickel. Nickel extraction was also suppressed following preoxidation at over 300°C. This was thought to be due to formation of slow‐leaching nickel oxide‐tungstate. Following preoxidation at the optimum of 300°C, 97% of the nickel could be leached in 4 h at 82°C using (by volume) 3% sulphuric acid and 0.6% nitric acid flowing at 1.5 litres/h. About 70% of the nickel could be extracted from preoxidized catalyst using only water for 40 h at room temperature. These findings are incorporated in a simple proposed flowsheet.