Abstract: 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° C.

Abstract: 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° C.

Abstract: A method of recovering antimony and bismuth from copper electrolyte comprises the steps of immersing a pure copper material in the copper electrolyte, so that the iron ions are reduced from Fe.sup.3+ ions to Fe.sup.2+ ions, using a mixture of dilute sulfuric acid and sodium chloride adjusting the acidity or acidic concentration, to selectively elute the bismuth and antimony wherein if the final concentration of bismuth is adjusted to be 0.02 g/l or less in the bismuth election, it is possible to keep the maximum concentration of bismuth in the antimony eluate in the elution of antimony after selective bismuth elution to 0.01 g/l or less.

Abstract: 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 wi

Abstract: 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.