高マグネシア酸化ニッケル鉱の還元アンモニア浸出に及ぼすジャロサイト添加の影響

Abstract

In order to investigate the reducibility of Ouinne ore (from New Caleuonia) known as nickel oxide ore containing a significant amount of magnesia, reduction roasting and ammonia leaching have been conducted for the ore. Moreover, trials of improving the reducibility have been done by means of adding jarosite to the ore. Some of results obtained are as follows.1) Leaching rates of Ni and Co in ammonia leaching were improved by heating reduction (simultaneous reduction with heating) as compared with preheat reduction (reduction after preparatory heating). When the ore was roasted by heating reduction in H2 (50%)-H2O mixed gas atmosphere at 973 K, leaching rates of Ni and Co were about 65% and 55% respectively.2) When the ore was roasted with a small amount of ferric sulfate or potassium jarosite in the reducing atmosphere, thel eaching rate of Ni improved remarkably in the ammonia leaching. These additives seem to act as sulfidation agent on amorphous oxide temporarily and to prevent crystallization to forsterite of difficult reducibility.3) When the ore was roasted with about 1O% potassium jarosite in H2 (99.9%) atmosphere by heating reduction at temperature between 873 and 973 K for 40-50 minutes, leaching rates of Ni and Co were 85% and 65% or more respectively. These results are also interesting from the point of utilization of jarosite.