Hong-In Kim

Sulfuric acid baking and leaching of spent Co-Mo/Al2O3 catalyst

Dissolution of metals from a pre-oxidized refinery plant spent Co-Mo/Al(2)O(3) catalyst have been tried through low temperature (200-450 degrees C) sulfuric acid baking followed by mild leaching process. Direct sulfuric acid leaching of the same sample, resulted poor Al and Mo recoveries, whereas leaching after sulfuric acid baking significantly improved the recoveries of above two metals. The pre-oxidized spent catalyst, obtained from a Korean refinery plant found to contain 40% Al, 9.92% Mo, 2.28% Co, 2.5% C and trace amount of other elements such as Fe, Ni, S and P. XRD results indicated the host matrix to be poorly crystalline gamma- Al(2)O(3). The effect of various baking parameters such as catalyst-to-acid ratio, baking temperature and baking time on percentage dissolutions of metals has been studied. It was observed that, metals dissolution increases with increase in the baking temperature up to 300 degrees C, then decreases with further increase in the baking temperature. Under optimum baking condition more than 90% Co and Mo, and 93% Al could be dissolved from the spent catalyst with the following leaching condition: H(2)SO(4)=2% (v/v), temperature=95 degrees C, time=60 min and Pulp density=5%.

A noble Process to Recover Metal Values from Spent Hydrodesulphurization Catalyst

ABSTRACT A combination of pyro-and hydro-metallurgical process has been proposed to selectively recover molybdenum, cobalt and aluminium from the spent hydrodesulphurization catalyst containing 12.3% Mo; 31.8% Al; 2.38% Co; 9.5% S and 2.9% C. Before a two stage alkali-acid leaching process to selectively target Mo, Co and Al from the uncrushed sample, the spent catalyst was roasted at different temperature. Characterizations of different roasted samples were carried out in order to understand the structural changes and dissolution behavior of spent catalyst. Mo was selectively separated and recovered from the leach liquor by carbon adsorption method; whereas, Al and Co were separated by an organo-phosphinic based extractant, Cyanex 272. In the whole process, 95.9% Mo, 89.6% Co and 39.8% Al was recovered from the spent catalyst.