Application of Sherritt’s Pressure Hydrometallurgical Technology to Other Metals
Much of Sherritt’s metallurgical and product technology developed over the last 50 years can be traced back to work done during the development of the ammonia leach process. Pressure leaching of sulphide ores and concentrates, using continuous horizontal autoclaves, provided the basis for a thriving pressure hydrometallurgical process licensing business which offered processes for treating nickel mattes and concentrates, zinc concentrates, and refractory gold ores and concentrates. The nickel reduction process perfected in the Ottawa pilot plant was subsequently licensed worldwide.
During the early 1950’s, following the successful commissioning of the nickel refinery at Fort Saskatchewan, Sherritt utilized its laboratory and pilot plant facilities in Ottawa to look for other potential applications for pressure leaching processes in the metals industry (14). Laboratory tests were carried out on the pressure leaching of uranium ores and on the pressure oxidation of refractory gold ores, where the oxidative pressure treatment proved an excellent method for oxidizing pyrite and arsenopyrite to liberate the gold for subsequent recovery.
Two additional leaching plants were built by Chemico to treat cobalt concentrates in the aftermath of the Korean War, when the cobalt price was artificially high, but both plants became uneconomic as the price of cobalt declined, and closed in the early 1960s. A fourth pressure leaching plant was the Port Nickel plant, constructed by Freeport to treat the nickel-cobalt sulphide from Moa.