1、 Principle analysis:

In acidic solutions, cobalt generally exists in the form of Co ² ⁺ ions. After adding magnesium oxide to the solution, the following reaction occurs:

MgO + H₂O → Mg²⁺ + 2OH⁻

OH ⁻ combines with Co ² ⁺ in the solution to form cobalt hydroxide precipitate:

Co²⁺ + 2OH⁻ → Co(OH)₂↓

The generated cobalt hydroxide is a light pink or light purple precipitate that is insoluble in water and can be recovered through solid-liquid separation.

2、 The advantages of magnesium oxide as a cobalt precipitant:

Mild alkaline source: Compared to strong bases such as NaOH and Ca (OH) ₂, MgO hydrolyzes slowly and has a milder pH control, making it suitable for finely controlling precipitation reactions.

No introduction of impurity ion pollution: Mg ² ⁺ is relatively harmless in solution and does not affect subsequent metal recovery.

The ingredients are pure and can be reused: Mg ² ⁺ in the filtrate after cobalt precipitation can be recovered or directly reused.

High selectivity for other metals: Under suitable pH conditions, cobalt can be preferentially deposited instead of copper or nickel.

3、 Factors affecting the cobalt deposition effect:

PH control: Generally, the best effect is achieved within the range of 8-9. If it is too high, other metals may co precipitate.

Temperature: Increasing the temperature helps accelerate the precipitation reaction.

Reaction time: A certain amount of stirring and reaction time is required to ensure complete precipitation.

Particle size: Nanoscale or ultrafine magnesium oxide has high activity and higher precipitation efficiency.