Sumitomo Metal Mining Company, Ltd.

Naoyuki Tsuchida

Yoshitomo Ozaki

Masaki Imamura

Kazuyuki Takaishi

Susumu Makino

Hiroshi Kobayashi

Hirofumi Shouji

Sunao Kanesaka

Atsushi Goda

Kazunori Furukawa

A hydrometallurgical process based on pressure leaching at elevated temperature for recovering nickel from nickel oxide ores, characterized by a simplified and efficient process as a whole, realizing a simplified leaching stage, reduced neutralizer consumption and precipitate production in the neutralization stage, and efficient use of recycled water. The hydrometallurgical process of the present invention, comprising a leaching stage which stirs the slurried ore in the presence of sulfuric acid at 220 to 280&#xb0; C. to produce the leached slurry; solid-liquid separation stage which washes the leached slurry in multi-stages to produce the pregnant liquor and leached residue, the former containing nickel and cobalt; neutralization stage which treats the pregnant liquor in the presence of calcium carbonate incorporated to keep the pH level at 4 or less, while suppressing oxidation of the liquor, to produce the neutralization precipitate slurry and mother liquor for nickel recovery, the former containing trivalent iron; and a sulfide precipitation stage which blows hydrogen sulfide gas into the mother liquor to produce the sulfide solution and barren liquor, the former containing nickel and cobalt.

Hydrometallurgical process of nickel oxide ore

A method of purifying a crude nickel sulfate solution to give pure nickel sulfate through solvent extraction, in which the impurities such as cobalt, calcium, magnesium, iron, zinc, copper, sodium, ammonia and others to be in the crude solution are removed while, if necessary, effectively recovering cobalt, and for which the amount of a neutralizer to be used is reduced and the cost of treating wastewater is also reduced includes an extraction step of adding an organic acid extractant to a crude nickel sulfate solution to thereby extract nickel into the extractant to give a nickel-loaded organic phase, followed by a scrubbing step of scrubbing the organic phase as obtained in the previous extraction step with a nickel-containing scrub solution to thereby remove sodium and ammonia from the organic phase; and a second purifying step of adding a crude nickel sulfate solution to the nickel-retaining organic phase as obtained in the previous first purifying step so as to exchange the nickel in the organic phase with the impurities except sodium and ammonia existing in the crude nickel sulfate solution added in this step, thereby giving a purified nickel sulfate solution and an organic phase containing impurities; and optionally a third purifying step of recovering nickel from the organic the organic phase containing impurities as obtained in the second purifying step, and a step of recovering a valuable metal, cobalt from the organic phase containing impurities.

Method for purifying a nickel sulfate solution by solvent extraction

A method of solvent extraction of a nickel sulfate solution uses a multi-stage, counter-current, organic solvent extraction system composed of at least two extractors connected in series, and includes a first extraction step of feeding a crude nickel sulfate solution that contains sodium and ammonium impurities into a second-stage extractor, wherein it is treated in countercurrent flow and at a pH of 6.5 to 7.0 with an organic extractant fed into the second-stage extractor from the first-stage extractor, to thereby extract some of nickel in the crude nickel sulfate solution into the organic extractant; and a second extraction step of transferring the nickel-containing, organic phase to an organic phase-scrubbing step to remove sodium and ammonium, while transferring the nickel sulfate solution, from the first extraction step and from which some of nickel has been removed, to the first-stage extractor, wherein it is treated in countercurrent flow and at a pH of 5.5 to 6.5 with a fresh organic extractant, to thereby extend the remaining nickel in the nickel sulfate solution into the organic extractant. The nickel-containing organic phase from the second extraction step is divided into two portions, one portion being fed into the second-stage extractor while the other portion is transferred to a by-pass, organic phase-scrubbing step it to remove sodium and ammonium.

Method of solvent extraction of nickel sulfate solutions

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Niihama, Japan

Naoyuki Tsuchida