Competing Solvent Extraction of Calcium and/or Nickel With Cyanex 272 and/or D2ehpa

Abstract

The present study assessed the competing behavior between metals and extractants applied to the solvent extraction of calcium and/or nickel present in sulfuric solutions using the extractants Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) and/or D2EHPA (di-2-ethylhexyl phosphoric acid). Tests were designed to allow equivalent competing conditions between metals and extractants. Considering metal competition in the aqueous phase, calcium extraction remained unaffected in the presence of nickel, while nickel extraction curves with pH displaced to the right in the presence of calcium when D2EHPA (ΔpH 1/2 = 1.4) or Cyanex 272 + D2EHPA (ΔpH 1/2 = 0.9) were used. Considering extractant competition in the organic phase, metal extractions with Cyanex 272 + D2EHPA closely followed the curves obtained with D2EHPA, thus evidencing that it acts as the main extractant agent, synergism or antagonism effects being attributed to the presence of Cyanex 272. A synergistic increase in the calcium extraction occurred at pH ≥ 4.5, being unaffected in the presence of nickel, whereas rejection for nickel occurred in the whole pH range in the absence of calcium, and at pH < 5.5 in the presence of calcium. For the operating conditions investigated, Ca/Ni separation reached a maximum at pH = 4.5 (calcium extraction > 80%, nickel extraction < 0.25%, β Ca/Ni = 2159).

Recovery of cobalt from lithium-ion battery cathode material by combining solvoleaching and solvent extraction

“…This is one of the reasons that sulphuric acid is nowadays still the industrial preferred lixiviant. 57,58…”

“…21 D2EHPA is much less acidic than mineral acids and the water content in D2EHPA is neglibible. 57,58 These factors reduce the undesired formation of hydrogen gas, leaving aluminium unaffected in the leaching residue. [59][60][61] Hence, metals can show a remarkable different behaviour in organic media, which is observed when only the current collectors (without LCO) are leached and compared in Fig.…”

“…This is one of the reasons that sulphuric acid is nowadays still the industrial preferred lixiviant. 57,58 In contrast to D2EHPA, sulphuric acid can leach lithium and cobalt quantitatively in absence of reducing agents. However, this is only achieved after 24 hours leaching.…”

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

“…When pH eq ‡ 3, the extraction of Ni, Co and Mg increased, whereas the extraction of Ca decreased slightly as a consequence of the crowding out effect of Ni. 27 The results in Fig. 3b reveal that after a single contact with 10 vol.% Na-D 2 EHPA at a pH eq = 2.5, > 89% of Ca can be extracted, while the extractions of Mg (10.5%), Co (7.2%) and Ni (0.6%) are much lower, leading to an associated SF Ca/Ni of 1267.…”

Selective and enhanced nickel adsorption from sulfate- and calcium-rich solutions using chitosan

“…Ni is present in many industrial effluents, including those of silver refineries, electroplating, zinc base casting, and storage battery industries [9], where its concentration usually ranges from 0.05 to 15.3 mM [10]. In many cases, these effluents are complex as there are other ions coexisting with Ni; two of the most ubiquitous being sulfate (SO4 2-) and calcium (Ca) [11][12][13][14].…”