Sherritt ammonia pressure leaching

Sherritt ammonia pressure leaching. This hydrometallurgical process was first implemented in 1954 by Sherritt Gordon Mines in Fort Saskatchewan, Alberta, Canada. In this process, the finely ground nickel sulfide concentrates obtained after flotation or the metal matte are reacted at 80 to 95°C in a high-pressure autoclave under 850 kPa with an oxygenated ammonia or ammonia-ammonium sulfate liquor. Ammonia dissolves nickel and, to a lesser extent, cobalt, zinc, and copper by forming soluble ammonia complex cations as follows ... 

Cobalt can be recovered from nickel-sulfide concentrates or nickel matte by the Sherritt-Gordon ammonia leaching process in Fort Saskatchewan, Alberta, Canada, and it is also recovered from sulfuric-acid pressure leaching of laterites. In both cases, cobalt is obtained in nickel-free liquor by reduction with hydrogen under elevated pressure and temperature (Section 2.2). 

Another important example is the leaching of nickel sulfide under ammonia and oxygen pressure to form hexaammine nickel (Sherritt-Gordon process). 

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