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Leaching with Alkalies
Published in C. K. Gupta, T. K. Mukherjee, Hydrometallurgy in Extraction Processes, 2019
The off-gas issuing out of the top of the still contains NH3 and CO2 which are recovered and recycled. The nickel carbonate slurry is filtered, washed, and calcined to yield nickel oxide. The calcination reaction is shown below: () 3Ni(OH)2⋅2NiCO3→5NiO+3H2O+2CO2
Hydrometallurgy
Published in C. K. Gupta, Extractive Metallurgy of Molybdenum, 2017
The spent catalyst contains a number of valuable metals such as nickel, tungsten, vanadium, and molybdenum. A process sequence involving roasting, grinding, pressure leaching, and solid-liquid separation to yield concentrated solutions of the metals was established on a plant scale based on research and development programs carried out at Cotter Corp., Canon City, CO. For nickel-molybdenum catalysts, the process consisted initially of roasting. The roasted product was then wet ground and subjected to continuous leaching with an ammonium carbonate-ammonium hydroxide solution in autoclaves at elevated temperatures and pressures. Autoclaving resulted in solubilization of nickel as amine carbonate and of molybdenum as ammonium molybdate. After solid-liquid separation, the solution was subjected to steam stripping by which nickel precipitated as nickel carbonate, leaving behind molybdenum in solution. After filtration, molybdenum from the enriched solution was extracted by a solvent (Alamine 304) and finally precipitated as calcium molybdate.
Short-Bed Ion Exchange
Published in Arup K. SenGupta, Ion Exchange and Solvent Extraction, 2007
In electrolytic copper refineries, high-purity copper is electrolytically recovered from a solution containing about 50 g/L copper and 150 g/1 sulfuric acid.31 Metallic contaminants such as nickel, antimony, and bismuth build up, eventually to the point where electrolyte must be purged to limit the level of contamination. For example, at Falconbridge’s Kidd Creek copper refinery in Timmins, Ontario, Canada, electrolyte was bled at a rate of 67 m3/day to control nickel buildup. An APU was commissioned in 1995 to recover the sulfuric acid values from the decopperized electrolyte bleed stream. The recovered acid is recycled back to the tank house, while the deacidified nickel salt stream is neutralized with soda ash to recover nickel carbonate, which is sold. Several other refineries have installed APUs for similar applications.
The influence of leaching parameters on the extraction of vanadium from petroleum coke
Published in Petroleum Science and Technology, 2019
Natalia K. Kondrasheva, Viacheslav A. Rudko, Roman Ev. Lukonin, Ivan O. Derkunskii
Queneau et al. (1989) developed a method of recovery of vanadium and nickel from petroleum coke by hydrometallurgical method. The experiment was carried out on petroleum coke obtained from oils and tars of North and South America. The core of the process was the oxidation (burning) of coke under pressure to solubilize vanadium as sodium vanadate (NaVO3). The process was carried out at 300 °C and pH = 9,5 using wet oxidation in industrial reactors and the extraction of vanadium occurred in an amount of 85–99% vol. in terms of V2O5. Nickel concentrated in ash mainly in the form of Nickel carbonate (NiCO3). For the conversion of NaVO3 to V2O5 with a high degree of purity in this work, the traditional solvent extraction technology and subsequent crystallization was recommended.