The investigations of the reduction-roasting ammonia leaching procedure on the Pomalaa low grade nickeliferrous oxide ore were carried out.
Additive pyrite, calcium chloride and/or sodium chloride were used.
The ore sample used for experiment was the mixture prepared from serpentinic and limonitic ore. When pyrite and calcium chloride were used together, nickel leaching ratio becamed 86% and was stabilized until dosage of one percent of pyrite.
This combination contributed toward the stabilization and higher extraction of nickel, and depression of iron and magnesium in the wide range of reduction temperature of 750-900°C, pyrite of 0.25-1.0%, calcium chloride of 2.5-10%, hydrogen gas saturated with steam of (69-87%H
2-31-13%H
2O) and the mixing ratio of limonitic ore of 0-15%.
When pyrite and sodium chloride were used together, nickel extraction ratio was also improved considerably. Its ratio, however, showed the value lower than it of calcium chloride.
Combination of pyrite, calcium chloride and coal as the fuel and the origin of reduction gas was also effective for nickel and copper leaching, and depression of iron and magnesium.
Dosage of calcium chloride, futhermore, had a possibility of the decrease to about one percent.
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