INVESTIGATION OF ALKALINE LEACHING AS A PRECONCENTRATION METHOD ON A TURKISH NICKEL LATERITE AND ITS EFFECT ON SUBSEQUENT ACID LEACHING

Date

2026-8-24

Author

Chapepa, Reginald Ngoni

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The aim of this study was to evaluate alkali leaching as a preconcentration method on a Turkish nickel laterite ore, with particular focus on its effects on nickel and cobalt enrichment and subsequent acid leaching performance. Alkali leaching was conducted under atmospheric pressure using sodium hydroxide to selectively extract silica from the ore while retaining metal elements in the solid residue, thereby achieving relative enrichment of nickel, cobalt, and other metals. Under optimum conditions, nickel and cobalt grades increased by 17.54% and 18.11% repectively, with 99.92% nickel recovery and 84.35% cobalt recovery in the residue. The effects of the preconcentration were investigated by comparing the alkali-treated ore with raw ore used as a control. Subsequent agitated acid leaching tests were conducted under atmospheric pressure at varying temperature and acid dosage levels to evaluate the effect of prior alkaline treatment on nickel extraction. The results indicated that the alkali-treated ore produced lower nickel recoveries than the untreated ore, particularly at low acid dosages. However, this difference became less pronounced with increasing acid dosage. Under the optimum conditions established for the untreated ore, nickel recovery reached 98.67%, compared with 93.68% for the treated ore. Despite the slight decrease in extraction efficiency, the treated ore provided higher absolute nickel output, more efficient acid dosage utilization, and potential reductions in downstream neutralization reagent requirements.

Subject Keywords

Acid leaching, Pretreatment, Alkali leaching, Nickel laterite, Hydrometallurgy

URI

https://hdl.handle.net/11511/120652

Collections

Graduate School of Natural and Applied Sciences, Thesis