D = Corg / CaqCorg and Caq: concentrations of the metal at lequilibrium, in the same unit.
Use when: The distribution ratio depends on conditions, including pH and composition.
Purification by solvent extraction
Understand the transfer of a metal between aqueous phase and organic phase.
What is happening?
SX brings two poorly miscible liquid phases into contact. An extractant promotes the selective transfer of a metal to the organic; the phases are then separated by decantation.
Extraction charges the organic, while re-extraction transfers the metal to a new solution. Partition balance, flow ratio and contact kinetics influence performance.
The formulas, with their conditions.
E = D Vorg / (Vaq + D Vorg)E: extracted fraction; Vaq, Vorg: volumes.
Use when: A contact at equilibrium, constant volumes, organic initially without metal and D considered constant.
Where is this principle used?
SX–EW copper plant
Purify and concentrate the metal before electroextraction.
Hydrometallurgical refinery
Separate certain metals according to the selectivity of an extractant.
What to observe in the experiment
Compare extraction and re-extraction. Identify in each step the phase that gains metal.
References and readings
This sheet explains the principles and their assumptions. Educational simulation can simplify the process; an industrial model requires suitable data and validation.
Have you understood the essentials?
Only one correct answer per question. Answer all three questions, then view the answer key.
Intu Lab · Understanding sheet · Kimba Christian