Cobalt Recovery from Waste Catalysts (Petroleum Refining Industry from Gujarat)

Palanivel Sivasakthi, Natarajan Sathaiyan

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Department of Electro-Hydro Metallurgy, Central Electrochemical Research Institute, Karaikudi, India.

DOI: 10.4236/ojmetal.2012.21004                

Abstract

A hydrometallurgical process has been developed for cobalt recovery from a waste catalyst (petroleum refining industry). This waste catalyst containing about 2.18 weight % of Co, is highly contaminated by Mg, Al, Si, Ca, Fe, Ni, Cu, Zn, Mo. The major steps are: (I) The spent catalyst is roasted with flux material in an electrical furnace at very high temperature (700?C) for a specific duration. (II) The roasted sample is leached with sulphuric acid to bring the metal contents into solution form. (III) For separating cobalt values from the leach solution, the solution pH is raised by NaOH addition, where all cobalt content is precipitated at a pH of about 12. (IV) This cobalt hydroxide precipitate is filtered and dissolved in minimum amount of sulphuric acid to get cobalt sulphate solution which is used as the electrolyte for the electrolytic recovery of cobalt. For optimizing various parameters like (1) H2SO4 concentration; (2) Duration; (3) Cobalt concentration; (4) Current density; (5) Temperature; (6) Stirring etc., The particle surface morphology and deposited layers have been characterized by scanning electron microscopy (SEM). A compact metallic deposit containing 70% cobalt was obtained.

Keywords

Hydrometallurgical; Electrowinning; Cobalt; Flux Material; Waste Catalysts; H2SO4 Leaching

Conflicts of Interest

The authors declare no conflicts of interest.

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