MS(s) ā MĀ²āŗ + SĀ²ā» ; Kā = a(MĀ²āŗ) Ć a(SĀ²ā»)a: dimensionless activities, fixed standard state.
Use when: Example of a MS sulfide; adapt the expression to the real stoichiometry.
Sulfide solubility and dissolution
Distinguish between chemical balance, speciation and dissolution rate of a sulfide ore.
What is happening?
The dissolution of a sulfide depends on the activity of the ions, the pH, the redox potential and the complexes formed. The free sulfide concentration can be very different from the total dissolved sulfur.
Thermodynamics indicates a trend and a state of equilibrium; kinetics describes the time necessary to approach it. Passivation and transport can slow down even though favorable dissolution.
The formulas, with their conditions.
X(t) = (mā ā mrĆ©siduelle) / māX: dissolved fraction; m: masses of the monitored phase.
Use when: Correct the masses of samples and phases which do not react.
Where is this principle used?
Hydrometallurgical plant
Choose a solution scheme and follow its tests.
Treatment of mining effluents
Study the mobility of metals and their precipitation.
What to observe in the experiment
Change pH and reaction time separately. Distinguish an equilibrium limit from simply slow dissolution.
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 Ā· Understanding sheet Ā· Kimba Christian