Flotation Strategies for the Recovery of Nickel from Mine Tailings

Document Type

Article

Publication Date

1-1-2026

Abstract

Nickel is critical for stainless steel production, batteries, and next-generation clean energy technologies; its sustainable recovery is becoming increasingly important as primary ore grades decline globally. Once considered waste, mine tailings are now recognized as a valuable secondary resource due to their residual nickel content. The main nickel minerals in the tailings sample used in this study are pentlandite and pyrrhotite, both of which are sulfide minerals. However, because mine tailings are left in open pits for long periods, surface oxidation and hydration occur, making sulfide mineral surfaces more hydrophilic and therefore more difficult to float. This study investigated advanced flotation strategies for recovering nickel from mine tailings and low-grade nickel ores. Bench-scale flotation experiments were conducted to evaluate activation flotation, activation–sulfidization flotation, mixed-collector flotation, and CO₂-assisted flotation. The addition of (NH₄)₂SO₄ as a secondary activator improved flotation selectivity, likely by dispersing slime coatings and exposing active sulfide sites. The use of AERO OX 100 as a co-collector with sodium isobutyl xanthate (SIBX) further enhanced nickel recovery, particularly during scavenger flotation. CO₂ flotation also improved flotation performance under optimized activation–sulfidization conditions, increasing the concentrate Ni grade from 0.92% with air to 0.95% with CO₂. Based on these results, an advanced activation–sulfidization–CO₂ flotation flowsheet was developed. The rougher stage employed SIBX as the collector and CO₂ as the flotation gas, while the rougher tailings were treated using a mixed-collector system with CuSO₄ and (NH₄)₂SO₄ as activators and Na₂S as the sulfidizing agent. The optimized process produced a concentrate containing 1.13% Ni at a recovery of 72.45%. The flotation concentrates and middling products were proposed as feedstocks for downstream activated-carbon-assisted sulfuric acid leaching, salt-roasting–acid leaching, or bioleaching, followed by solution purification and electrowinning. These results demonstrate the potential of integrating flotation and hydrometallurgical processing for nickel recovery from secondary and low-grade resources.

Publication Title

Mining Metallurgy and Exploration

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