METHOD OF ENHANCING THE ATMOSPHERIC LEACHING OF NICKELIFEROUS MATTE

METHOD OF ENHANCING THE ATMOSPHERIC LEACHING OF NICKELIFEROUS MATTE A method is disclosed for preparing matte for the atmospheric acid leaching thereof. Such mattes include nickeliferous sulfide mattes (e.g. nickel sulfide and nickel-copper sulfide mattes) containing 30% to 75% nickel, up to about 50% copper, up to about 10% Co, 4% to 25% sulfur and up to about 5% iron, the nickel (cobalt), copper and sulfur content making up at least about 90% by weight of the matte. The amount of sulfur contained in the matte is less than that required stoichiometrically to combine with the metal values therein and does not substantially exceed that amount required to combine with nickel as Ni3S2. The method resides in establishing a bath of said molten matte of predetermined composition, the temperature of the molten matte being at least about 100.degree.C higher than its liquidus-solidus temperature, following which the temperature of the molten matte is lowered to a granulating temperature relative to said liquidus-solidus temperature so that the granulating temperature falls within the range of about 50.degree.C above and about 100.degree.C below said liquidus-solidus temperature. The molten matte is thereafter quenched in the presence of a quenching fluid from said granulating temperature, and then comminuted to the desired size for leaching, thus providing a feed product characterized by improved dissolution characteristics with respect to the nickel therein when subjected to atmospheric leaching in a hot acid solution.