Out of the twenty nine (29) mining companies in the country with nickel as primary commodity, only two (2) undergo mineral processing operations. The rest are engaged in the direct shipment of such ores. The said 2 processing plants utilize high pressure acid leaching (HPAL) with sulphuric acid as leaching reagent. However, given the expensive materials of construction and high energy requirements for HPAL, atmospheric leaching processes have been proposed.

In this study, laterite ore was subjected to agitated atmospheric leaching tests to investigate the effects of leaching temperature, leaching time, stirring speed, dilution ratio, and acid concentration on the extraction of nickel. Nickel content in the pregnant solutions, as well as the tails, will be determined through Atomic Absorption Spectroscopy.

Initial results of leaching tests showed promising results on the extraction of nickel. The use of other lixiviants, such as hydrochloric acid, nitric acid and sodium hydroxide, must also be conducted. Optimization tests will then be carried out to establish an economical nickel beneficiation scheme that might be used in lieu of HPAL.

Keywords: Laterite, Agitated Atmospheric Leaching, Sulfuric Acid

Engr. Chris G. Arnejo, Engr. Carina V. Pecson and Engr. Rey V. Perucho
Mineral Processing Research and Development Section (MPRDS)
Metallurgical Technology Division
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