High Purity Nickel Recovery from an Industrial Sidestream Using Concentration and Liquid–Liquid Extraction Techniques

Abstract

This article outlines an alternative flowsheet for the purification of a multimetal industrial sidestream (16.3 g/l Ni, 0.7 g/l Co, 0.6 g/l Ca and 1.6 g/l Mg) to allow high-purity nickel recovery. The methodology comprises an initial evaporation step to achieve Ca removal followed by impurity (Ca, Mg) and valuable (Co, Ni) element separation via two-step solvent extraction with organophosphorus extractants. Results indicate that > 80% of Ca is selectively removed as CaSO 4 AE2H 2 O by evaporation with a concentration degree > 6. In the following treatment, $ 90% of residual Ca (0.6 g/l) can be selectively extracted with Na-D 2 EHPA. The subsequent solvent extraction step with Na-Cyanex 272 separates Co (> 99%) and Mg (> 95%). The resultant nickel sulfate solution (61.7 g/l Ni, 0.3 g/l Mg and Co 0.007 g/l) of > 99.5% purity can be directly integrated into state-of-the-art nickel recovery processes.

Solvent Extraction Process for Refining Cobalt and Nickel from a “Bulk Hydroxide Precipitate” Obtained by Bioleaching of Sulfidic Mine Tailings

“…Because of the low concentrations of metals in the bioleaching stage, downstream processing might include a precipitation step to concentrate the leached metals in solid intermediates, often in the form of a mixed hydroxide precipitate MHP or a mixed sulfide precipitate MSP . These intermediates are further processed to recover valuable metals. , Distinct downstream purification may be applied, including selective oxidation and precipitation, which may be combined with solvent extraction (SX). ,− The more practical solutions adopted by the mining industry might rely on chemical precipitations, e.g., sulfide precipitations, achieving metal sulfides and mixed metal sulfide (e.g., Ni/CoS) products . However, SX-based flowsheets provide the advantage of selectively separating metals from complex aqueous solutions, achieving a high degree of separation, which may reflect in high-purity products, craved by the modern industry, e.g., battery materials. , …”

Are molecular solvents, aqueous biphasic systems and deep eutectic solvents meaningful categories for liquid–liquid extraction?

“…In particular, this technique has been investigated for the treatment of nickel [2], zinc [3], cupper [4] and lanthanide [5] -rich ores, among others. It is also a technique of choice for the recovery of valuable metals from several secondary sources [6][7][8][9][10][11] and for nuclear fuel reprocessing [12][13][14]. Based on its success, this technique is the subject of an intense and vivid academic interest, both on the fundamental side, in view of the understanding of extraction mechanism [15][16][17], or on an applied perspective (see for example the patent CA2785001A1 published in 2018, for purifying uranium from nitric acid dissolution 1 ).…”