Process for recovery of metal values from alnico scarps by electro-chemical leaching technique

• Operation at the desired kinetics.
• Cobalt leach liquor can be produced on the continuous scale.
• No grinding and agitation required.
• Ease of operation and complete recovery.
• Commercially feasible flow sheet.

This paper reports the study on the dissolution behavior of the alnico scraps generated during the manufacture of alnico permanganate magnets. Composition of the scrap used in the study was: 26.09% Co, 16.36% Ni, 47.02% Fe and 8.04% Al. Electroless leaching of the alnico scraps with sulphuric acid had no significant influence on the extraction of metals and which was due to the low surface area and less activity of the scraps. In order to improve the leaching efficiency, electric current was introduced to the system. Various experimental factors such as time, sulphuric acid concentration and current density were studied to determine the best conditions for the dissolution of the metal values. Effective leaching of scrap was due to the synergistic effect of ferric sulphate and temperature both generated during leaching with the current and sulphuric acid concentration in the system. Based on the leaching efficiency, they could be order as Ni > Fe > Co > Al. Under optimum leaching conditions (sulphuric acid 10% (v/v), current density 400 A/m2 and equilibrium time 4 h), more than 99% of the metal content was dissolved. Based on the process steps involved, a flow sheet was proposed for the commercial application.

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