Testing by the Departments of Mines and Technical Surveys and of Agriculture showed that mine water and slope ore from Denison Mines contained bacteria belonging to the Ferrobacillus-Thiobacillus group. Percolation leach tests showed that the bacteria promote the
production of an acid-oxidizing solution effective in leaching, whereas in the absence of bacteria no leaching of the uranium occurred
A chemical process, based on laboratory investigations, is proposed for the production of high-purity niobium oxide from a pyrochlore-perovskite flotation concentrate produced from ore obtained at the Oka, Quebec, property of Columbium Mining Products Limited.
The method developed included the decomposition and dissolution of the flotation concentrate with hot, concentrated sulphuric acid. The dissolved niobium was purified and concentrated by a solvent extraction step, using methyl isobutyl ketone as the extractant. The niobium was recovered from the
extractant with ammonium fluoride solution from which niobium oxide was precipitated with ammonia. Finally- , the filtered and washed precipitate was calcined. Ninety-six per cent of the niobium was recovered in a product analysing 99.9 per cent Nb 204 . The reagent cost was in the range of $1.00 to
$1.25 per pound of niobium recovered.
The effect of leaching Canadian scheelite concentrates with weak hydrochloric acid at pH 1.0 prior to treatment by a previously described Mines Branch process was investigated. The work showed that the weak-acid leach removed about 25 per cent of the iron, 90 per
cent of the phosphorus, 10 per cent of the calcium and 0.1 per cent of the tungsten from a scheelite concentrate analysing 54.4 per cent W03 , 15.8 per cent CaO, 3.9 per cent Fe, and 0.43 per cent P. The overall cost on the basis of acid consumption and tungsten loss would be about $0.04 less per
pound of tungsten than for the original Mines Branch process where the weak-acid leach was not used.
The uranium mines of Elliot Lake area in Ontario, Canada, were brought into production in the mid-1950's. At that time the extraction plants were designed to utilize an acid leaching process which, although adequate in that about 95 percent extraction of the
uranium was attained, was not thoroughly understood. Because of this the plant operators found it necessary to make trial-and-error adjustments to the operating conditions, one of the more important of these being to increase the temperature of the pulp during leaching. It was found that as the
leaching temperature increased the acid addition needed for acceptable extraction decreased, the combined effect being a reduction in operating costs. A recent laboratory study has served to clarify further this relationship between leaching temperature and acid requirement. At the same time the
effects of other operating variables were also studied more thoroughly than had been done in the past. The results of this investigation, which are reported in this paper, not only supplied new information related to the extraction of uranium from the Elliot Lake ores, but also emphasized the fact
that currently used processes may not be understood sufficiently. Consequently, it may be profitable for operators to study existing processes further before they embark on major process changes.
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