UBC Theses and Dissertations
Solvent extraction of nickel from complexation leachate solution Xiao, Yuchang
Hydrometallurgy uses aqueous solution chemistry for the recovery of metals from various materials. Complexation leaching uses chelating agents to bind targeted metals. Solvent extraction may then be used to recover and separate the target metal. This work focuses on the solvent extraction of nickel from complexation leaching solution. LIX 84-I was selected as an extractant to effectively recover nickel from near neutral leach solution in the presence of the complexing ligand. The recovery of nickel is determined by the thermodynamic relationship between the metal-ligand and metal-extractant formation. The factors that influence the thermodynamic equilibrium were investigated. The phase ratio (A/O) was studied. Solvent extraction involves the mixing and contact of an aqueous and organic solution. The kinetics of solvent extraction are therefore very important to minimize the equipment size and time for phase transfer. Thus, reaction time and temperature were studied. The stability of the ligand in the solvent extraction process was also investigated. Results show that nickel ion/citrate ligand is suitable for the solvent extraction of nickel due to the ease of loading on the extractant LIX 84-I and the ability to fully strip nickel at room temperature. However, a portion of citrate ligand is lost during the contact. The recycling and reusing of citrate ligand in the leaching process are therefore not ideal. Similarly, the loss of nitrilotriacetic acid ligand during the solvent extraction at high temperatures is measurable and therefore of concern. In comparison, ethylenediaminetetraacetic acid, ethylenediamine-N,N‘-disuccinic acid, and tetrasodium glutamate diacetate ligands are more stable during the solvent extraction process, but the kinetics of nickel extraction are too slow to permit industrial processing. It is recommended that additional factors such as higher temperature are explored to improve kinetics of nickel extraction (within the limits of safety).
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