Lentrant centrant + Lapport capport = Lsortant csortant + Lretenu cretenuL: liquid flow; c: concentration; Lc products in the same unit of solute flow.
Use when: Solute balance of a stage without reaction, in steady state.
Counter-current decantation (CCD)
Understand backwashing and recovery of entrained solute.
What is happening?
A CCD cascade circulates solids and wash water in opposite directions. The cleanest liquid meets the solids which leave the circuit, while the more charged solutions return upstream.
Washing recovers the species already dissolved in the liquid retained by the pulp. It must be distinguished from additional leaching of the solid; the yield depends on the stages and their mixing–separation efficiency.
The formulas, with their conditions.
Rlavage = 1 − ṁsoluté perdu / ṁsoluté entrantR: fraction recovered, or ×100 in%.
Use when: Define dissolved solute and circuit boundaries.
Where is this principle used?
Copper–cobalt leach plant
Recover the dissolved metals before discarding the residue.
Chemical and sugar industry
Wash solids by successive contacts.
What to observe in the experiment
Compare a short waterfall and a longer waterfall at the same water input, then track the solute lost with the residue.
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