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Nickel Recovery from Spent Catalyst of Reformers

Raei Niaki, AhmadReza | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43195 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Halali, Mohammad
  7. Abstract:
  8. In this research, Nickel recovery has been investigated from spent catalyst (NiO/Al2O3) in reformers of direct reduction iron plant (Midrex). Genetic Algorithm method was applied for screening and optimization of the parameters affecting on the Ni dissolution in sulphuric acid by means of Design Expert Software. In accordance with the results, temperature, time, acid concentration and particle size were introduced as the effective parameters on the catalyst leaching. In the next step, the optimization experiments, the optimal parameters were achieved as following: Temperature = 95 C, Acid concentration = 5 Molar, Time = 255 minute, Stirring speed = 600 rpm, Particle size = 50-60 micron and Solid/Liquid = 30 g/l. In the next step, for comparison of the dissolution power between sulphuric acid and nitric acid, the catalyst was leached in nitric acid under the same conditions which had been done by sulphuric acid. The results showed that nitric acid power for nickel oxide leaching is significantly more than sulphuric acid power so that the maximum recovery was achieved 98% by nitric acid and 78% by sulphuric acid. In the kinetic study step, Shrinking Core Model has been introduced as the research’s kinetic model where the kinetic of nickel oxide dissolution is controlled by a mixture mechanism including the chemical reaction mechanism and diffusion mechanism. In according to the new proposed model, the activation energy for Nickel oxide dissolution has been achieved by Arrhenius equation as following: 1. in sulphuric acid = 30.76 kJ 2. In nitric acid = 22.62 kJ
  9. Keywords:
  10. Catalysts ; Nickel ; Recovery ; Hydrometallurgy ; Kinetic Model

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